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a certain battery of diagnostic laboratory tests will aside. Multiple blood tubes can be fi lled in this manner. be performed to help discern the pathology and guide the Once the phlebotomy is completed, a cotton gauze pad is treatment. placed over the needle insertion site and the needle quickly The red top tubes are sometimes called clot tubes withdrawn in the direction opposite of insertion. Cotton balls because the tube contains no additives or preservatives to should not be used as they tend to adhere to and pull out plate- prevent blood clotting. Without additives, such as an antico- let plugs at the insertion site. With the bleeding controlled, agulant, the blood clots and the serum rise to the top. The the Paramedic can proceed with marking the blood tubes with percentage difference between the amount of space fi lled by the name of the patient, the date and time of the phlebotomy, the clot (formed elements such as red blood cells) and the and the Paramedic’s initials. total volume is the hematocrit. The patient’s hematocrit is an After placing the blood tubes in a clear plastic bag, the important indicator, particularly for trauma patients. Paramedic should ensure the blood tube’s safe transportation Samples of the serum are used to test the blood chemis- to the receiving hospital. Some Paramedics tape the blood try (i.e., the electrolytes, etc.) in the blood. The clot is used tubes to the outside of the intravenous solution bag. This prac- to identify the variety of blood (blood-typing) and to cross- tice is acceptable provided the contents are clearly visible. match it to blood that is available in the blood bank. It is The use of a nonsterile glove is discouraged, as the contents important that the serum separates from the formed elements inside the glove are not visible. All potentially infectious in the blood; therefore, it is counterproductive to invert or materials (PIM) must be clearly marked with the biohazard shake the blood tube. symbol or some other warning that indicates the presence of The light blue and lavender-topped tubes have anticoagu- PIM. A cut sustained from the broken glass of a blood tube lants (3.2% sodium citrate and sodium EDTA, respectively) is an exposure to blood-contaminated sharps and may be a added to them to prevent the blood from clotting. These anti- reportable incident. coagulant tubes are used for special clotting studies, such as the partial prothrombin time (PPT), as well as red blood Pediatric Phlebotomy cell studies, including hematocrit and hemoglobin (H&H). The laboratory results from these studies are important if Drawing blood from a child can be a challenge. By applying the patient is destined for the operating room or may receive the principles of pediatric venous access (discussed later in fi brinolytics. the chapter), along with the principles of phlebotomy (just A number of other blood tubes are available—gray, discussed), the Paramedic can expect to have success. green, royal blue, and yellow—and each has a specifi c indi- A heel stick is performed to obtain a blood sample from cation. For example, tan-topped tubes have sodium heparin, an infant. A heel stick—puncturing the infant’s heel with a another anticoagulant, and are used for tests of lead. lancet then drawing the blood off with a capillary tube—is When in doubt, or when no orders exist, a standard blood performed on newborns. Practice while under the careful sample usually includes drawing a red-topped tube, a blue- supervision of a practiced provider is the best means for Para- topped tube, and a lavender-topped tube. The order of the medics to master this technique. blood draw is also important. To prevent potential contamina- For older children, phlebotomy is performed as it is on tion from additives, the tubes without additives (red-topped adults, with a few exceptions. Children have smaller veins; tubes) are drawn fi rst and the “wet” tubes (those with addi- therefore, smaller needles (25 g to 27 g) are used to draw tives) are drawn last. blood. Children’s veins also tend to collapse under the pres- To perform a phlebotomy, the Paramedic could prepare sure that a vacuum tube system produces. Venous collapse the site as if an IV access was going to be attempted. Fre- can be averted by either using a pediatric vacuum tube sys- quently, the preferred site for a phlebotomy is the antecubital tem or using a 5 mL or 10 mL syringe attached to a butterfl y fossa, although any peripheral vein is acceptable. needle. Gentle intermittent traction on the syringe’s plunger Commonly, a straight hollow-bore needle attached to a will gradually draw the sample from the vein. With a little vacuum tube apparatus is used for phlebotomy. With the vein patience, the application of age-specifi c therapeutic interven- prepared, the needle shield is removed from the needle and tions, and the right equipment, the Paramedic can expect to the gloved dominant hand stabilizes the vein. The needle is be successful with a phlebotomy on a child. 578 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Blood Cultures Age-Appropriate Approaches to Pediatric When a patient has a fever or the Paramedic suspects that the Patients with IV Access patient may have septicemia (an infection in the blood), then Regardless of a child’s age, each child views intravenous a blood culture could be drawn. The blood culture is a special therapy as a painful procedure that he would rather avoid. laboratory analysis used to test the blood for the presence of Gaining a child’s trust and cooperation will tend to improve sources of infection called pathogens. Common blood cul- success with pediatric IV access. Trust and cooperation is ture specimen collection units are either aerobic and anaero- earned when the Paramedic carries out the child’s IV therapy bic (Figure 27-29). Blood cultures usually involve obtaining with an age-appropriate therapeutic approach. enough blood to fi ll two broth-containing blood tubes or As a general rule, the Paramedic should not separate the bottles, the broth being a medium for bacterial growth. One child and parent during the IV attempt. However, practice, of the blood cultures is used to test for aerobic microorgan- experience, and personal interaction with the parent is a better isms and the other blood culture is used to test for anaerobic basis for that decision. Involving the child in the preparations microorganisms. and decision making may help the child feel more in control, It is important that medical asepsis be practiced whenever a provided the child is not given the opportunity to say no, and blood culture is drawn. The venous access site must be cleansed helps foster trust between the Paramedic and the child. with a povidone-iodine-based solution, such as Betadine®, or The child should never be told, by either the Paramedic similar antigermicidal solution and the solution allowed to or the parent, that the insertion of an IV will not hurt. dry. While the solution is drying on the skin, the Paramedic Rather, the focus should be on the benefi t of the IV and how should take a new swab and cleanse the top of the blood culture quickly the IV will be over. Needless to say, this places a tube/bottle. The remainder of the phlebotomy would proceed burden on the Paramedic to ensure that all of the necessary as usual. Although practices vary from hospital to hospital, in supplies are immediately available and prepared. Similarly, every case medical asepsis is practiced the prevention of acci- the child should not be told that only one IV attempt will dental contamination of the specimen is important. be necessary. The number of IV attempts is a function of the child’s condition and the importance of the IV. Finally, Pediatric Intravenous Access regardless of a child’s age, he should be encouraged to cry, Pediatric intravenous access can be challenging to even the privately, without fear of ridicule, and to express his anger most experienced Paramedic. The key to success in pediatric or frustration without fear of judgment. The Paramedic IV access is to match the IV access site chosen to the urgency understands that these outbursts are not meant personally. of the situation and then take a therapeutic approach to the Such expressions are healthy and an indication that the child that is matched to the child’s developmental level. child is coping appropriately with the situation. The choice for a peripheral pediatric venous access can Developmentally speaking, infants are learning trust and be very age-dependent, owed to the child’s changing body have a strong child–parent bond. The infant may not trust the habitus. For example, an umbilical venous access may be Paramedic but does trust the parent to protect him. A parent appropriate in a newborn whereas a venous access in the dor- should be encouraged to comfort the infant before and after sal venous arch of the hand may be more appropriate for a the venipuncture. Often a pacifi er can help to sooth the infant toddler. while the procedure is going on; however, the infant should not be given a bottle-feeding, as the risk of vomiting and aspi- ration offsets any advantage. If the infant is fussy, and there is a risk of accidental catheter displacement, then a swaddling board (e.g., an infant blanket over a short padded board) may be used to immobilize the infant. Toddlers exhibit their growing autonomy by attempt- ing to assert their control. The toddler should be dealt with matter-of-factly and told (in simple, age-appropriate terms) what is about to happen. Age-appropriate distractions are often very useful at this age as the child attempts to dem- onstrate her self-control. However, it is not uncommon for a child at this age to regress. A parent should be available to comfort the child. Preschoolers are capable of assisting with preparation and setup (e.g., tearing pieces of tape) and want to appear confi dent. However, preschoolers have a fear of the unknown, particularly about pain. Therefore, they should be told, in a Figure 27-29 Blood culture specimen straightforward manner, what is going to occur. This approach collection units. helps to eliminate some of the fear-producing fantasy the Intravenous Access 579 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. child might imagine. When the IV access has been obtained, the preschooler should be commended for her cooperation and permitted to express her emotions. Paramedics may be taken back by the articulate manner which the preschooler may express herself. School-aged children, up to adolescence, are thoughtful and generally understand the implications behind the state- ments that the Paramedic makes. The Paramedic should encour- age the school-aged child to ask questions and then provide answers at an age-appropriate level. Limited decision making, such as determining the arm that the IV is to be started, can help the child feel more in control and less fearful. Adolescents can be treated like an adult, more or less. Time spent with fuller explanations and a question and answer period helps to gain both their trust and their coopera- Figure 27-30 Umbilical catheter attached to a tion. Adolescents are concerned about body image and peer three-way stopcock. approval. The Paramedic should be forthcoming with praise regarding positive aspects of the relationship and avoid any criticism of the adolescent’s conduct. In some instances, an adolescent may be content to listen to music from a head- the catheter. Opening the stopcock, the Paramedic should set while the IV is being started. This is not a demonstration gently aspirate, by pulling back on the syringe’s plunger, until of contempt or aloofness, but rather an

effective distraction a free fl ow of blood is observed. technique. With the catheter now in place, fl uids and/or medica- tions (such as 0.1 mg of epinephrine 1:10,000) can be rapidly Umbilical Venous Access (UVC) administered. The Paramedic should tighten the umbilical tie For a newly born, with a medical emergency, it may be pos- to secure the umbilical catheter in place and prevent exces- sible to gain venous access via the umbilical cord to adminis- sive bleeding from the umbilical stump. ter fl uids and drugs, such as epinephrine. The umbilical cord, that rope-like appendage between mother and child, has two Scalp Vein Access arteries and one vein, surrounded by Wharton’s jelly, and has The thought of inserting a needle into an infant’s scalp may no nerves. The two umbilical arteries carry deoxygenated sound bizarre to many Paramedics. However, pediatricians blood from the fetus to the placenta, and the umbilical vein and pediatric nurses have used scalp veins for venous access carries oxygenated blood from the mother to the fetus. Some for decades. Scalp veins can provide a reliable venous access umbilical cords, however, have only two vessels: an artery that is easy to obtain and even easier to maintain. and a vein. Newborns with only two vessels often have asso- The scalp veins are generally very prominent, have no ciated congenital anomalies. valves to interfere with cannulation, and are only thinly To begin, the Paramedic would loosely tie off the umbili- obscured by the fi ne hair of the infant. The most commonly cal cord, around the base, with cloth umbilical tape. Tying used scalp veins are the metopic vein, located at the mid- the umbilical tape too tight can prevent the passage of the forehead region, and the superfi cial temporal veins located venous catheter. If the tie is too loose, as evidenced by bleed- bilaterally on the forehead (Figure 27-31).52 A broad rubber ing, it can be re-tied tighter later. The umbilical stump is now band placed around the head at approximately ear level will cleansed with a povidone-iodine solution. While waiting for help distend the scalp veins. the povidone-iodine solution to dry, the Paramedic would The infant should be restrained, as needed, and the area prefi ll a 5 French umbilical catheter with NSS via a syringe prepared. Using scissors, any negligible amount of hair attached to a three-way stopcock (Figure 27-30). should be clipped and the area cleansed with povidone-iodine After donning sterile gloves, the Paramedic would take or similar antiseptic solution, using care to not have the solu- the sterile scalpel and perform a perpendicular transection tion run into the eyes. of the umbilical cord proximal to the clamp. Examination of After fl ushing the intravenous catheter (either a butter- the cord should reveal three orifi ces—two arteries and one fl y needle or an over-the-needle device) with sterile saline, vein—with the vein typically at the 12 o’clock position. The the Paramedic would pull gentle traction on the vein with thicker-walled arteries are usually inferior, at 4 and 8 o’clock, the nondominant hand and proceed with inserting the nee- unless the cord is twisted, which is a common presentation. dle. When a fl ash of blood is visible, the tourniquet can be The umbilical catheter would be advanced through the removed and a small amount of saline solution injected to test umbilical vein, the larger orifi ce, and toward the heart for a the catheter’s patency and position. distance of approximately 2 to 4 cm. Once the umbilical cath- If the saline solution fl ushes easily, without evidence of eter is past the orifi ce, there should be a fl ash of blood inside infi ltration, then the IV catheter should be secured in place. 580 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Next, the vein needs to be distended. Adult venous tour- niquets apply too much pressure and pinch the child’s ten- der skin. It is easier and more effective if another Paramedic encircles the limb, with a fi rm grasp, effectively distending the veins while stabilizing the limb. Next, the venous access sites are chosen. The venous access sites for a child are generally the same as an adult’s access sites. The Paramedic may have diffi culty fi nd- ing an IV access site on a pudgy infant’s forearms, so the use of warm compresses can increase venous distention and improve visualization; observing caution to prevent burns. With the IV site selected, the Paramedic should choose the appropriate IV device. Generally, Paramedics choose to use the butterfl y IV needle. Butterfl y needles should not be placed in freely movable joints but rather in areas, such as the scalp or dorsum of the hand, which can be immobilized. To insert a standard IV catheter into the dorsum of the hand, the Paramedic should grasp the child’s fi ngers with the thumb, pulling traction on the vein while immobilizing the hand. Once the hand is stabilized, the Paramedic would approach the vein with the needle almost parallel to the skin Figure 27-31 Anatomy of infant scalp veins. and advance the needle until a fl ash of blood is visible in the catheter’s hub. It is good practice to immobilize the limb with the IV Many Paramedics place a clear plastic cup-like shield over catheter to a padded short board. Caution should be observed the site to protect it from incidental trauma. to ensure that the securing straps/tape is not acting as a venous tourniquet, creating backpressure, compromising the IV site, and possibly causing an infi ltration. Street Smart Next, the IV site should be dressed. After the transparent dressing is in place and the tubing is secured, with an omega Infants and children cannot tolerate a fl uid overload loop, a length of protective netting can also be applied length- wise along the limb. The netting permits observation of the as well as an adult. Immature kidneys have more site while protecting the tubing, catheter, and so on. Alterna- diffi culty adjusting to the changing electrolytes tively, a small paper cup can be cut in half and placed over the and fl uid osmolarity that occur with a massive fl uid site to act as a protective shield. infusion. For these reasons, pediatric intravenous infusions are run cautiously and through a burette or Street Smart an infusion pump in most cases. If time permits, the use of EMLA or ethyl chloride solution, two topical anesthetics described earlier, Peripheral Pediatric Venous Access can markedly reduce the child’s discomfort.53 The techniques for peripheral venous access are the same for children as they are for adults with just a few minor variations. However, attention to these differences will help to ensure the Pediatric Intraosseous Access Paramedic is successful in obtaining venous access in a child. In high-priority situations, such as pediatric cardiac arrest, Unlike adults, children cannot be expected to remain immediate venous access is imperative. In those cases, estab- motionless while an IV needle is being inserted. Two Para- lishing an IV catheter is too time-consuming and has the medics may be needed: one to start the IV and the other to deal attendant risk of failure. In times of high peril, an intraosseous with the child, including restraining the child as needed. The infusion is indicated.46, 54–57 When time is of the essence, the child should be placed supine. In an ambulance, it is common intraosseous route offers many advantages over traditional to have the parent sit at the head of the stretcher, to comfort peripheral venous access. To begin, the intraosseous route the child, while two providers sit on each side. Use of a small remains available even during cardiac arrest, unlike periph- blanket, used as a swaddling cloth, can help immobilize a eral venous access that collapses. Next, the intraosseous child. With one limb exposed, the child is ready for an IV. infusion can generally be established within a minute and a Intravenous Access 581 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. half. Then, once the needle is in place it is essentially fi xed to marrow may all be injected back into the bone and the intra- the bone and is fast and secure. Finally, the amount of distal venous administration line connected. blood fl ow inside the bone’s marrow quickly clears medica- The needle should be standing upright, without support. tion and circulates it directly to the central circulation and The IO needle’s fl anges, if available, can be secured to the onto the heart. limb with tape to provide protection from accidental displace- Common complications of intraosseous needle (IO) ment. A sterile dressing is then usually placed around the IO placement include misplacement of the needle, inadvertent needle fi rst. A split gauze pad can be used, although precut puncture of the posterior wall of the bone, and extravasation surgical sponges are available commercially. of fl uids into the tissues. Other complications, such as inter- After the intravenous solution is connected, the clamp is ruption of the growth plate and osteomyelitis, are rare if the released. The solution should run freely, and then slowed to Paramedic closely follows needle insertion guidelines. the desired rate of infusion. The posterior portion of the limb While technically there are numerous locations for an should be palpated for evidence of infi ltration. Intravenous intraosseous needle placement, Paramedics concentrate on solution infusing into the soft tissues will swell the tissues, four primary sites. The fi rst site, and the site of choice, is making them fi rmer in the process to the touch. the proximal tibia.58 The insertion site on the tibia is located As is the case with all peripheral venous access, attempts approximately 2 centimeters, or two fi nger widths, distal and should begin distal and move proximal. Once a bone has had medial to the tibial tuberosity on the tibial plateau. Alterna- one attempt made for IO access, it should not be used again. tively, another insertion site is available on the distal femur, 2 centimeters above the distal epicondyle and in the midline of the femur. While the distal tibia, proximate to the medial Central Venous Access malleolus, and the anterior iliac spine are also acceptable Ideally, the best route of medication administration would sites, they are rarely used by Paramedics. be by injection directly into the central circulation where it Intraosseous needles, like all other peripheral venous can be quickly carried to the target organs almost instantly. access, cannot be placed into an extremity with a fractured Central venous access, long intravenous catheters placed into bone. If the limb has a painful, swollen area, secondary to the great vessels, provides a route for central venous medi- trauma, then a fracture should be suspected and the area cation administration. An access to the central venous sys- avoided for IO needle placement. tem would also permit the measurement of central venous Once the desired insertion site has been identifi ed, the pressure (CVP), a measurement used to assess a patient’s Paramedic should prepare the site with a povidone-iodine swab hemodynamic status. Finally, central venous access permits or similar antiseptic solution. While surgical asepsis is not nec- frequent blood sampling without the annoyance of repeated essary, it is important that Paramedics practice strict medical needlesticks. asepsis, taking all precautions to prevent bone infection. It is estimated that fi ve million central venous access If the child is conscious, then it may be necessary to infi l- devices (CVAD) are placed annually in the United States trate the area with an

anesthetic such as 2% lidocaine. How- alone. A small fraction of those are put in place by Paramed- ever, in the fi eld, the placement of an intraosseous needle is ics in the fi eld. However, every Paramedic should know how generally performed under emergency conditions. The patient to access a CVAD during an emergency. is either unconscious or semiconscious and can feel the pain. With the intended site properly prepped, the Paramedic Types of Central Venous grasps the limb from above with the nondominant hand to stabilize the limb. The limb should not be held in the palm of Access Devices the hand. The risk of slipping with the IO needle and piercing A large number of central venous access devices are available the palm is too great. The IO needle is now placed against the on the market. Some CVADs are put in place during a special skin at a 90-degree angle perpendicular to the skin or slightly surgical procedure whereas others can be placed in the fi eld caudal, away from the epiphyseal plate (growth plate) and during an emergency by specially trained Paramedics. The inserted with a twisting action. As the IO advances, it will common feature of all of the central venous access devices advance quickly until it meets the resistance of the bone’s is that they place the distal tip of a catheter proximal to the cortex. At this point, the Paramedic must make a forceful, but junction of the vena cava with the right atrium. Because of controlled, insertion into the bone with a twisting action. the high fl ow at the catheter’s distal tip, it is possible to infuse After removing the IO needle’s stylet, the Paramedic irritating or hypertonic solutions as well as inject normally should attach a sterile 10 mL syringe and attempt to aspi- incompatible drugs consecutively. rate bone marrow. The absence of bone marrow, a common The original central venous catheters, the Broviac® and occurrence, does not indicate that the IO needle is out of the the Hickman®, were developed during the 1970s and used bone. If the aspirate is unsuccessful, then a 10 mL bolus of extensively in the critical care areas. These skin-tunneled physiologic saline should be attempted. Use of a saline-fi lled devices exit the body in the vicinity of the right, or left, syringe during aspiration makes it easier to visualize the clavicle and have a medication access port for medication fl ash of bone marrow and blood. The saline, blood, and bone infusions. A central venous access device could remain 582 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. in place for fi ve to seven days, and potentially up to two weeks in special cases, thus avoiding the trauma of repeated needlesticks. The next generation of central venous access devices, the percutaneous central venous catheters (PCVC), were inserted into the deep veins via the subclavian vein (in the chest), the internal jugular vein (in the neck), and the femoral vein (in the groin). These central venous catheters have been developed with single-, double-, and triple-lumen catheters (Figure 27-32). Later CVAD models included an implanted port that was accessed from the outside by a special needle (described later) that could remain in place for even longer periods of time, an advantage during chemotherapy. The most recent addition to the line of central venous access devices is the peripherally inserted central catheter (PICC). The PICC is a very long catheter placed within a vein in the antecubital fossa and threaded into the vena cava Figure 27-33 PICC line used to administer while under fl uoroscopy. Subsequent radiographs of the chest antibiotics, at home, to a 12-year-old trauma are taken to confi rm placement of the PICC. Newer PICC patient who subsequently had developed devices are fi ber-optic. The progress of these newer fi ber- osteomyelitis. optic PICCs allows the provider to observe the progress of the catheter under the skin and into the vena cava. The ease Field-Placed Central Venous of placement, without fl uoroscopy, permits the insertion of a PICC in the physician’s offi ce, or in the fi eld. Access Device The PICC is rapidly becoming the CVAD of choice for The value of obtaining central venous access in the fi eld must patients who are at risk for hemorrhage, secondary to antico- be weighed against the dangers of CVAD placement. While agulants or low platelet counts (thrombocytopenia), or who the advantages of central venous access (e.g., during cardio- are immunocompromised. The site is easily accessible and vascular collapse) are impressive, the disadvantages, includ- visible (for infection surveillance) and compressible (in cases ing accidental arterial puncture with subsequent hemorrhage of hemorrhage). The PICC line, properly maintained, can and permanent nerve damage, can outweigh those advan- remain in place for over a year, and many patients are sent tages. For those reasons, CVAD placement in the fi eld is gen- home with a PICC in place (Figure 27-33). erally reserved for cases where a critical or cardiac arrested patient could clearly benefi t and the risks are outweighed by the benefi ts. The choice of the device is a function of the method of insertion. While the long catheter-over-the-needle CVAD may seem more familiar to the Paramedic, as it is similar to the regularly used peripheral intravenous access device, overinsertion of the long needle has serious implications for the patient, such as creation of a pneumothorax or accidental arterial puncture. An alternative CVAD is the catheter-through-the-needle device, described earlier in the chapter. This CVAD is less popular among Paramedics because the opening it creates in the vein is larger than the catheter that will pass through it. Subsequently, there can be hemorrhage at the site. This CVAD is reserved almost exclusively for use in compressible sites, such as the veins within the antecubital fossa. The preferred method of central venous access in the fi eld is the catheter-over-the-guidewire CVAD. This device starts with a smaller intravenous needle, which is familiar to Paramedics, and progresses to a larger catheter. The technique for inserting a catheter-over-the-guidewire will be described shortly. Although a variety of external central venous access Figure 27-32 Triple-lumen catheter, a central devices are available, each with a different number and/or venous access device. gauge of catheter, these catheters are generally either 20 cm Intravenous Access 583 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. long, for use in the subclavian or internal jugular vein, or 60 thigh rotated slightly. When the insertion site for the CVAD cm long, for femoral or basilac veins. has been identifi ed, it must be adequately prepared before proceeding with the needle insertion. While not a sterile pro- Placement of the Central Venous cedure, the insertion of devices into the central circulation Access Device (bypassing many of the body’s immune defenses in the pro- A number of sites are available for the placement of a central cess) requires strict medical asepsis. venous access device, and each has its drawbacks. The inter- The immediate area surrounding the area should be nal jugular vein (JV), while readily accessible, is in the same swabbed with a povidone-iodine or similar antiseptic solu- vicinity as other resuscitative efforts, such as intubation. This tion, starting at the intended point of insertion and moving makes it inconvenient. Furthermore, the proximity of the outward in ever-expanding, overlapping circles until an ade- carotid arteries to the internal jugular vein makes insertion of quate fi eld has been created (usually a 6- to 8-inch circle). If a needle into the internal jugular vein more problematic and the area is covered with hair, obscuring the insertion site, it an “overshoot” could cause arterial puncture. However, in the may be necessary to either clip the hair with scissors (pre- hands of an experienced operator, the IJV has the highest rate ferred) or shave the area. Excessive time should not be spent of success with the lowest incidence of complications.59 clearing the area of unwanted hair. The Paramedic would then An alternative location for a CVAD could be the sub- palpate for the femoral pulse with a gloved hand. The femoral clavian vein. Located inferior to the clavicle, the subclavian pulse should be located approximately 2 cm below the ingui- vein is proximal to the apex of the lung. An all-too-common nal ligament at the midpoint of the mental triangle. complication of a subclavian CVAD insertion is the creation Using the Seldinger technique, a catheter-over-the-wire of a pneumothorax. technique, the Paramedic will cannulate the femoral vein. Another complication of insertion, seen with the catheter- With a fi nger on the pulse, the Paramedic inserts the long over-the-wire approach, is the positioning of the wire inside 18g intravenous needle and catheter at a 30-degree angle, the heart. As the wire is literally whipped against the walls of approximately 1 cm medial to the femoral pulse, with the tip the heart with each contraction, it can create an ectopic beat aimed toward the head into the femoral vein. When the Para- and dysrhythmia. This site, like the IJV, is in proximity to medic observes a blood fl ash, the needle is stabilized with other resuscitative efforts. the nondominant hand and the needle withdrawn, leaving the The femoral vein is perhaps the safest site for the place- catheter in place. A special wire (a J-wire) is then inserted ment of a CVAD by an inexperienced operator. The topo- into the hub of the needle. The J-wire, a tightly wound spring graphic anatomy needed to identify the location of the femoral wire, has an open hook at the end, preventing it from punctur- artery is easy to locate. Therefore, the femoral vein can be ing soft tissues. cannulated without any serious interruption to either efforts Once the wire is in place, the needle is withdrawn. Dur- to intubate the patient or external cardiac compressions. How- ing the entire process, the Paramedic has a hold of either the ever, because the femoral CVAD lies below the diaphragm, needle or the J-wire. With the J-wire in place, a longer cath- it is not possible to measure accurate central venous pressure eter is placed over the wire and slid into position. After con- (CVP). This is generally not a priority in the out-of-hospital fi rmation of placement, the CVAD is secured in place and setting, whereas immediate venous access is a priority. fl uid fl ow rates adjusted accordingly (Skill 27-4). The femoral vein, like most deep veins, lies in a neuro- On occasion, a Paramedic may inadvertently misdirect vascular bundle, alongside the femoral artery and nerve. To the needle and puncture the adjacent femoral artery. If this locate the femoral vein, the Paramedic can trace its course occurs, and after the needle is withdrawn, a large dressing from the saphenous opening in the thigh to its terminus at the and direct pressure (with the palm of the hand, if necessary) inguinal ligament. The Paramedic should imagine a triangle, is applied to the area until the bleeding stops. a mental triangle, in the inguinal fold, with the femoral vein For a step-by-step demonstration of Obtaining a lying in the middle, within the femoral sheath. The femoral Femoral Line, please refer to Skill 27-4 on pages artery should be found, by palpation, just lateral to the vein, 591–592. and the femoral nerve lies lateral to the femoral artery (i.e., from inside to out, vein, artery, and nerve). Needle entry into the femoral vein is complicated by the presence of the super- Street Smart fi cial and deep fascia, a strong

membranous sheath that pro- tects these important structures. If intra-abdominal or pelvic injuries are suspected, Preparation and Insertion then the risk of distorted anatomy and subsequent of a Femoral CVAD accidental arterial puncture, as well as increased To perform a femoral insertion of a catheter-over-the-wire bleeding in the area, make the femoral site CVAD, the Paramedic must fi rst position the patient supine, undesirable for central venous access. with the legs abducted approximately 30 degrees and the 584 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Access of a Central Venous c onsists of a reservoir, a hollow metal disk with a self-sealing Access Device membrane, and a silicone catheter. This population of patients frequently has a medical Peripherally inserted central catheters (PICC), percutaneous emergency and requires EMS assistance, including medica- central venous catheters, and tunneled central venous catheters tions and/or fl uids. If traditional peripheral venous access all have external ports that provide easy access for Paramedics cannot be obtained during an emergency, and it is impera- in the event of an emergency. To access these devices, the Para- tive to gain such access, the Paramedic may elect to access medic disconnects the catheter cap, connects a syringe, draws the IVAD. Some Paramedics have been specially trained by off approximately 3 mL to 5 mL of solution (either physiologic oncology nurses or oncology specialists to access the IVAD saline or heparin), maintains the patency of the catheter, and during an emergency. discards the drawn off waster. Then the Paramedic connects the To access an IVAD, the Paramedic must fi rst locate the device intravenous administration set and adjusts the fl ow. in either the upper chest or upper arm. Once located, the skin If the catheter cap is a self-sealing membrane, similar to a overlying the IVAD is prepared in the same manner as a periph- medication port, then it will be necessary to cleanse the cath- eral IV site. Once the site is prepared, the Paramedic opens all eter cap with povidone-iodine solution and then introduce a necessary equipment, prefi lls a saline-fi lled syringe, and attaches needle-tipped syringe (usually a 19g needle) to withdraw the it to a special non-coring needle called a Huber needle. discard. Subsequently, a needle will need to be attached to Donning sterile gloves, the Paramedic carefully picks the end of the intravenous administration set securely and the up the Huber needle, avoiding contamination, and holds the two mated. Many Paramedics reinforce the connection of the Huber needle with the dominant hand. Taking the gloved needle to the catheter cap with tape. nondominant hand, the Paramedic holds the subcutaneous The greatest concern with accessing these devices is port fi rmly, like holding a quarter on its side, and places the accidental disconnection that can result in massive hemor- needle over the skin (Figure 27-34). rhage and/or air embolism. To prevent this potentially fatal If the patient were a child, many Paramedics would pre- complication, most CVAD have luer lock fi ttings that con- pare the site with EMLA cream before the procedure. In the nect together tightly and/or self-sealing membranes (similar case of adults, after repeated access, a callous commonly to those on a medication port) that seal the catheter. forms over the site, and the needle inserted is relatively pain- The insertion of a CVAD is a costly and time-consuming less. With the needle poised over the port and perpendicular process and it is important to maintain the patency, and thus to the skin, the needle is advanced, with authority, until the the viability, of a CVAD for these reasons. The patency of a needle strikes the back plate of the port and stops. With the CVAD can be maintained by either continuous infusion or needle in place, the Paramedic fi rst checks for a blood return, intermittent infusions (e.g., with heparin solution). Most Para- then fl ushes the IVAD. medics prefer that, once access has been made into a CVAD, Similar to a CVAD, once the IVAD is accessed the Para- the patency of CVAD is maintained by a continuous infusion, medic has a choice between continuous infusion and intermit- running at KVO, until the patient arrives at the hospital. tent infusion. Most Paramedics elect to maintain a continuous Implanted Vascular Access Devices infusion and attach the intravenous administration set adaptor to the hub of the Huber needle. The entire assembly can then be For long-term venous access, a special implanted vascular secured with a transparent occlusive dressing, with or without access device (IVAD) is used. An IVAD is a central venous gauze, under the arm of the Huber needle to help stabilize it. catheter that has the port buried in a subcutaneous pocket under the skin’s surface. Implanting the entire device affords the IVAD the skin’s protection, which decreases the rate of infection, as well as protect the port from physical trauma. IVADs are generally reserved for patients who are going to receive intermittent infusions of irritating solutions for a prolonged period of time (e.g., chemotherapy). Infusion of these irritating solutions via traditional peripheral venous access would cause the veins to become infl amed (sclerosis) and hardened. Venous access to these hardened veins becomes increasingly diffi cult over time and the patient is often sub- jected to repeated attempts. IVADs eliminate the need to attempt, and to re-attempt, IV access on those patients who have a poverty of veins. Instead, the IVAD is accessed. The infusion is run through a plastic catheter and into the central circulation, where it can be diluted. Figure 27-34 IVAD access with a Huber needle. The subcutaneous port of an IVAD may be implanted (Courtesy of Emergency Preparedness Systems, LLC and EMS in either the upper chest wall or the upper arm. The port Magazine) Intravenous Access 585 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Skill 27-1 Preparation of an Intravenous Administration Set 1 Select solution, checking for solution type, clarity, and expiration. 2 Select intravenous administration set, choosing between micro- drop and macro-drop. 3 Place the roller clamp just proximal to drip chamber and stopped. 4 Squeeze drip chamber, fi lling drip chamber one-half full. 5 Run solution out while maintaining sterility of end. 586 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Skill 27-2 Venous Cannulation Using a Catheter-Over-the-Needle Device 1 Apply the venous tourniquet and select the optimal site for 2 Cleanse the immediate area using appropriate antiseptic solution. cannulation. 3 Select appropriate venous catheter. 4 Visualize the insertion site (approach the site with authority). 5 Confi rm venous cannulation by looking for fl ashback in the 6 Slide the catheter over the needle into the vein. catheter. Intravenous Access 587 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Skill 27-2 ( continued) 7 Draw blood as appropriate and remove tourniquet. 8 Secure the IV catheter using a semipermeable membrane dressing. 588 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Skill 27-3 I ntraosseous Access 1 Identify the preferred site. 2 Prepare the site with antiseptic solution. 3 Approach the site with intraosseous needle, perpendicular 4 Aspirate to establish placement. to the bone. Intravenous Access 589 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Skill 27-3 ( continued) 5 Flush with saline, observing for infi ltration. 6 Attach administration set. 7 Secure IO access. 590 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Skill 27-4 O btaining a Femoral Line 1 Identify the femoral triangle. 2 Prepare the area with antiseptic solution. 3 Insert the needle and observe fl ash. 4 Thread the J-wire into the catheter. 5 Remove the catheter over the wire and hold the wire. 6 Introduce the dilator, then remove. Intravenous Access 591 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Skill 27-4 ( continued) 7 Thread the line over the wire, holding the line in one hand while 8 Attach the infusion set. threading with the other. 9 Dress the insertion site. 592 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Venous access for both fl uid replacement and medication administration during an emergency is critical. The Paramedic’s skill in obtaining venous access is often regarded as an indicator of the Paramedic’s capability. Without venous access, very little can be done to alleviate the patient’s suffering and lessen the pain. Key Points: • Body fl uids are distributed across three • After the correct solution has been chosen, the compartments: the intravascular space, intracellular Paramedic must verify that the solution is in date, compartment (ICF), and as extracellular fl uid (ECF) clear, and intact. in the interstitial space. • The intravenous administration set provides a sterile • Indications for intravenous access include pathway for the intravenous fl uid to get from the medication administration and the replacement of container into the patient. intravascular volume. • A macro-drop administration set is often used when • Fluid loss may be insensible (such as perspiration volume replacement is

needed. and vapor on the breath) or sensible (such as urine, GI fl uid loss, and wound drainage). • A micro-drop administration set is used for fi ne control of the infusion stream. • Pre-existing medical conditions that can contribute to increased fl uid loss include diabetes insipidus, • An administration set consists of a spike that pierces emphysema, hyperglycemia, and the alcoholic the fl uid container and a drip chamber where a patient. Decreased levels of responsiveness, hanging drop is formed. tachypnea, tachycardia, hypotension, or postural • A specifi c rate of fl ow may be established by hypotension may indicate a signifi cant loss of adjusting the fl ow to the required drops per minute. intravascular volume secondary to dehydration. • • The drip rate control device, slide clamp, and Crystalloid fl uids contain electrolytes commonly medication administration ports are located along found in the blood, while fl uids containing proteins the length of tubing, which is then connected to a are called colloids. catheter via an adaptor. • A balanced or isotonic solution has a percentage of • Trauma tubing has a larger internal diameter, solute similar to what is found in blood. allowing the rapid administration of large volumes • A solution that draws water out of the cell by of solution. Other infusion sets include large-bore osmotic force, due to a greater percentage of solute tubing found in blood transfusion sets and in-line than blood, is a hypertonic solution. burettes that are used to carefully control fl uid infusion, often used with pediatric patients. • A solution that has fewer solutes than blood, causing water to be drawn into the cells, is a • A pressure bag will increase the fl ow rate by hypotonic solution. exerting direct pressure onto the solution bag. • Intravenous access bypasses many of the body’s • Connecting and priming the administration set, or defenses against infection, so the Paramedic has the running the line out, begins by clamping off the line responsibility to take all reasonable precautions to and inserting the spike into the port of the solution. prevent blood infection. Fluid is then drawn into the drip chamber and the fl uid Intravenous Access 593 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. is run through the length of tubing. Venous access is • Venous cannulation can be performed by the direct divided into peripheral access and central access. approach by placing the IV needle atop the vein. • The indirect approach involves inserting the IV The smaller the gauge of an intravenous needle, the needle under the skin and next to the vein, and then larger the needle. directing the needle into the vein. The catheter must • A larger gauge needle is preferred for trauma be advanced into the vein to ensure placement. patients while a smaller gauge needle reduces the • When the needle is completely withdrawn, it must risk of thrombophlebitis and can be maintained for be immediately rendered safe. Some IV needles are a longer period of time. self-sheaving whereas others are not. Regardless of • The most common IV access device used is the the presence of any engineered safety devices, all needle-through-the-catheter variety. IV needles should be immediately placed in a sharps container. • Two other IV access devices include butterfl y IV catheters and needle-over-the-catheter devices, • The entire time for insertion should be approximately which are used almost exclusively for central venous two minutes, from the time the tourniquet was access in the hospital setting. applied to the time the tourniquet was released. Proper preparation of supplies, preassembled as • Whenever an intravenous access is attempted, a necessary, helps to improve overall effi ciency. sharps container should be immediately available (i.e., within arm’s reach of the Paramedic). • The IV administration set can be attached to the IV catheter and run continuously or intermittently. • A venous tourniquet should not remain in place for more than a few minutes and the distal • A saline lock can be used to cap off the IV catheter arterial pulse should remain palpable at all times. for later use. Tamponade of a vein, or manual compression of a • The IV catheter can be secured with tape and/or a vein, can achieve a similar effect. transported membrane dressing. • Venous access points of the upper extremity include • Several types of mechanical fl ow control devices the dorsal arch of the hand, cephalic and basilic may be used to accurately control intravenous fl ow. veins along the forearm, the cubital arch in the antecubital space, and the axillary vein in the upper • Complications of IV infusions include infi ltration, arm. Access points in the lower extremity include infusion-induced hypothermia, infection that may the saphenous veins. The external jugular vein may cause thrombophlebitis and/or pyrogenic reactions, also be accessed in an emergency. fl uid volume overload, or embolisms. • Venous site selection includes knowledge of hand • Infusing fl uids into the intraosseous space ultimately dominance, potential future procedures, past infuses fl uids into the central veins. surgical interventions, or current medical or trauma history. • Indications for IO access include cardiac arrest or the need for immediate access for medication • The Paramedic must assess and select a primary and administration. secondary IV site. • Complications of IO insertion include the risk • The Paramedic should clean the selected site by of fat embolism, fracture, extravasation, and placing the alcohol or povidone-iodine swabs on compartment syndrome. the intended insertion site and sweep outward in expanding and ever-widening circles, creating a • The majority of prehospital medications can be sterile fi eld twice the length of the IV needle. administered via the IO route except for 9% saline and adenosine. • The Paramedic should not re-palpate the intended IV access site once the preparation has begun. • Phlebotomy is performed when a blood sample is required but IV access is not necessary. Phlebotomy 594 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. is carried out using a straight needle and a vacuum • Pediatric intraosseous access provides vascular tube apparatus. access directly into the central circulation, can be • established quickly, and remains available even To prevent potential contamination from additives, during cardiac arrest. the tubes without additives (red-topped tubes) are drawn fi rst and the “wet” tubes (those with • Common complications include misplacement of the additives) are drawn last. needle, inadvertent puncture of the posterior wall • of the bone, and extravasation of fl uids into the When transporting samples, all potentially tissues. infectious materials (PIM) must be clearly marked with the biohazard symbol or some other warning • The IO site of choice is the proximal tibia. Like that indicates the presence of PIM. peripheral venous access, the IO needle cannot be • placed into an extremity with a fractured bone. Drawing blood cultures is a specialized technique that requires medical asepsis to prevent • Central venous access provides a route for contamination of the sample. medication administration as well as the • measurement of central venous pressure (CVP). Specialized phlebotomy techniques are used with pediatric patients. A heel stick may be used to draw • Central venous access devices include percutaneous blood from infants. A smaller needle, 25g to 27g central venous catheters (PCVC) that are inserted butterfl y, is used along with a syringe to gradually into deep veins and the peripherally inserted draw the sample from the vein. central catheter (PICC). • The umbilical catheter is advanced throughout the • For long-term central access, a patient may have an umbilical vein, the larger orifi ce. implanted vascular access device (IVAD). To access • this device, the Paramedic needs a special non- Scalp veins may also be used for IV access on infant coring needle called a Huber needle. patients. Review Questions: 1. Name the indications for venous access. 9. Starting proximal and moving distal, identify 2. What is a crystalloid solution? and describe the veins that may be used to 3. What role does the amount of solute play in the establish intravenous access. movement of water? 10. State the similarities and differences between 4. Describe insensible loss of fl uid and its intravenous access and phlebotomy. relationship to the disease process. 11. What precautions should be taken when 5. What clinical signs indicate dehydration? selecting an intravenous access site? 6. What type of intravenous administration 12. Describe the procedure for performing a set would you select for a trauma venipuncture. patient? Why? 13. Describe methods of securing the IV catheter. 7. Name the components of an administration set. 14. How is a secondary intravenous infusion 8. What are the steps to prepare a solution and prepared and set up? intravenous administration set? 15. What signs and symptoms would indicate a pyrogenic reaction? Intravenous Access 595 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. 16. Name the three basic vacuum blood tubes and 18. What are the indications for placement of an for which tests each is indicated. implanted central access device? 17. Describe age-appropriate methods of 19. What sites exist for an implanted central access establishing an IV for infants, toddlers, school- device? aged children, and adolescents. Case Study Questions: Please refer to the Case Study at the beginning of the 2. If you were unable to initiate an IV in her upper chapter and answer the questions below: extremities, what other sites exist that you can try? 1. Where would you look fi rst for access on 3. What other methods may be appropriate for Mrs. Gorino? Explain your answer. access? References: 1. Reithner L. Insensible water loss from the respiratory tract in 14. Zamos DT, Emch TM, Patton HA, D’Amico FJ, Bansal SK. patients with fever. Acta Chir Scand. 1981;147(3):163–167. Injection rate threshold of triple-lumen central venous catheters: 2. Lamke LO, Nilsson G, Reithner L. The infl uence of elevated an in vitro study. Acad Radiol. 2007;14(5):574–578. body temperature on skin perspiration. Acta Chir Scand. 15. Dutky PA, Stevens SL, Maull KI. 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Ann Pharmacother. 2007;41(10):1679–1686. cardiac tamponade as a result of a peripherally inserted central 47. Findlay J, Johnson DL, Macnab AJ, MacDonald D, Shellborn venous catheter: a case report and review of the literature. Br J R, Susak L. Paramedic evaluation of adult intraosseous infusion Anaesth. 2007;99(3):384–388. system. Prehosp Disaster Med. 2006;21(5):329–334. 30. Greenfi eld RH, Bessen HA, Henneman PL. Effect of crystalloid 48. Miller DD, Guimond G, Hostler DP, Platt T, Wang HE. Feasibility infusion on hematocrit and intravascular volume in healthy, of sternal intraosseous access by emergency medical technician nonbleeding subjects. Ann Emerg Med. 1989;18(1):51–55. students. Prehosp Emerg Care. 2005;9(1):73–78. 31. Lobo DN, Stanga Z, Simpson JA, Anderson JA, Rowlands BJ, Allison 49. Suyama J. Knutsen CC, Northington WE, Hahn M, Hostler D. IO SP. Dilution and redistribution effects of rapid 2-litre infusions versus IV access while wearing personal protective equipment in of 0.9% (w/v) saline and 5% (w/v) dextrose on haematological a HazMat scenario. Prehosp Emerg Care. 2007;11(4):467–472. parameters and serum biochemistry in normal subjects: a double- 50. Fowler R, Gallagher JV, Isaacs SM, Ossman E, Pepe P, Wayne blind crossover study. Clin Sci (Lond). 2001;101(2):173–179. M. The role of intraosseous vascular access in the out-of- 32. Schulze T, Mucke J, Markwardt J, Schlag PM, Bembenek A. hospital environment (resource document to NAEMSP position Long-term morbidity of patients with early breast cancer after statement). Prehosp Emerg Care. 2007;11(1):63–66. sentinel lymph node biopsy compared to axillary lymph node 51. LaSpada J, Kissoon N, Melker R, Murphy S, Miller G, Peterson dissection. J Surg Oncol. 2006;93(2):109–119. R. Extravasation rates and complications of intraosseous 33. Rietman JS. Geertzen JH, Hoekstra HJ, Baas P, Dolsma WV, de needles during gravity and pressure infusion. Crit Care Med. Vries J, et al. Long term treatment related upper limb morbidity 1995;23(12):2023–2028. and quality of life after sentinel lymph node biopsy for stage I or 52. Soong WJ, Jeng MJ, Hwang B. The evaluation of percutaneous II breast cancer. Eur J Surg Oncol. 2006;32(2):148–152. central venous catheters—A convenient technique in pediatric 34. Ververs JM, Roumen RM, Vingerhoets AJ, Vreugdenhil G, patients. Intensive Care Med. 1995;21(9):759–765. Coebergh JW, Crommelin MA, et al. Risk, severity and predictors 53. Zempsky WT, Cravero JP. Relief of pain and anxiety in of physical and psychological morbidity after axillary lymph node pediatric patients in emergency medical systems. Pediatrics. dissection for breast cancer. Eur J Cancer. 2001;37(8):991–999. 2004;114(5):1348–1356. 35. Lambert MJ, 3rd. Air embolism in central venous catheterization: 54. Hurren JS, Dunn KW. Intraosseous infusion for burns diagnosis, treatment, and prevention. South Med J. resuscitation. Burns. 1995;21(4):285–287. 1982;75(10):1189–1191. 55. Curran A, Sen A. Best evidence topic report. Bone injection gun 36. Kashuk JL, Penn I. Air embolism after central venous placement of intraosseous needles. Emerg Med J. 2005;22(5):366. catheterization. Surg Gynecol Obstet. 1984;159(3):249–252. 56. Skippen P, Kissoon N. Ultrasound guidance for central vascular 37. Deitch EA, Dayal SD. Intensive care unit management of the access in the pediatric emergency department. Pediatr Emerg trauma patient. Crit Care Med. 2006;34(9):2294–2301. Care. 2007;23(3):203–207. 38. Mackinnon MA. Permissive hypotension: a change in thinking. 57. DeBoer S, Seaver M, Morissette C. Intraosseous infusion: not just Air Med J. 2005;24(2):70–72. for kids anymore. Emerg Med Serv. 2005;34(3):54, 56–63; quiz 119. 39. Dubick MA, Atkins JL. Small-volume fl uid resuscitation for the 58. Driggers DA, Johnson R, Steiner JF, Jewell GS, Swedberg far-forward combat environment: current concepts. J Trauma. JA, Goller V. Emergency resuscitation in children. The role of 2003;54(5 Suppl):S43–S45. intraosseous infusion. Postgrad Med. 1991;89(4):129–132. 40. Idvall E, Gunningberg L. Evidence for elective replacement of 59. Sneff M. Central venous catheters. In: Rippe JM, Irwin RS, peripheral intravenous catheter to prevent thrombophlebitis: a eds. Intensive Care Medicine (2nd ed.). Boston: Little Brown; systematic review. J Adv Nurs. 2006;55(6):715–722. 1991:17–37. 41. Katz SC, Pachter HL, Cushman JG, Roccaforte JD, Aggarwal S, Yee HT, et al. Superfi cial septic thrombophlebitis. J Trauma. 2005;59(3):750–753. Intravenous Access 597 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. KEY CONCEPTS: Upon completion of this chapter, it is expected that the reader will understand these following concepts: • Components and production of blood • Blood groups, compatibility, and cross-matching • Identifi cation and treatment of transfusion reactions • Specifi c transfusion procedures before, during, and after transfer Case Study: The Paramedics were called to the local community hospital for a trauma patient who needed to be transferred to the trauma center. The patient had a serious motorcycle crash and his friends dropped him off at the hospital rather than calling for an ambulance. Now it was storming and the helicopter was grounded due to bad weather. The local hospital had placed a chest tube to drain blood from the patient’s thoracic cavity and he was receiving multiple blood transfusions. He would need more during the transport. 598 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Blood Products and Transfusion 599 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. OVERVIEW Blood product transfusion can be a life-saving therapy for patients who are critically ill or injured. In certain situations, the Paramedic may be asked to transfer patients who are undergoing a transfusion during an interfacility transfer. The Paramedic may also be asked to transfuse additional blood products during the transfer. These types of situations are often heavily regulated by each state’s oversight body and regulations differ from state to state. It is important for the Paramedic to follow the regulations and protocols for her state and agency. This chapter will discuss the different blood products and the indications for transfusing those blood products. History of Transfusions In the 1940s and 1950s, scientists developed meth- ods to separate whole blood into components that could be The fi rst recorded transfusion took place in 1665, when English transfused separately, thus improving storage capability and physician Richard Lower started transfusing blood between longevity as well as allowing more directed treatment of a dogs in his experiments. In 1667, French physician Jean-Baptist patient’s defi ciencies. Plastic bags were developed that were Denis transfused approximately 9 ounces or 260 mL of blood safe to use in storing blood. These replaced the cumbersome from a sheep to a young male patient. This patient survived and breakable glass bottles that were used at the time. but was described as having urine “as black as soot” after the transfusion. Dr. Denis continued animal to human transfusions over the following six months. Late in the same year, animal Professional Paramedic to human transfusion was outlawed in France and several other countries after several deaths were attributed to reactions to the animal blood. Around this same time, early microscopists were Carl Walter and W. P. Murphy, Jr., introduced the examining blood under the early microscopes and describ- plastic bag for blood collection in 1950. ing the different components of blood. While Anthony van Leeuwenhoek (1632–1723) is often credited with discovering During the 1960s and 1970s, important advancements red blood cells, scientist Jan Swammerdam actually discovered were made in the development and identifi cation of specifi c blood cells in the late 1650s. components that could be used to prevent antibody formation, The fi rst human-to-human transfusion was performed treat hemophilia, and detect infections that could be transmitted in 1795 by Dr. Philip Physick, a surgeon in Philadelphia, by blood product transfusion. The issue of transfusion safety Pennsylvania. The case was not publicized and little infor- moved to the forefront during the mid to late 1980s after dis- mation is available about it. A little more than 20 years covering the HIV virus was transmitted through blood transfu- later, British obstetrician James Blundell performed the fi rst sion. This led to widespread testing. Currently, donated blood is known blood transfusion to treat severe postpartum hemor- tested for several infectious diseases (Table 28-1). Due to wide- rhage by transfusing the blood from a husband to his wife spread testing and donation procedures designed to minimize after delivery. risk of disease transmission, the risk of contracting HIV from a In 1901, Austrian physician Karl Landsteiner discovered blood donation ranges from 1 in 493,000 to 1 in two million.1 the existence of

different proteins on red blood cells and was the fi rst to describe blood groups. The safety of blood transfu- sion improved as physicians began to match the patient’s blood Table 28-1 Infectious Diseases Tested group with the donor’s blood group. In addition, around the for in Donated Blood time of World War I methods were discovered to prevent blood • HIV-1 from clotting during storage. Researchers also discovered that blood could be stored at cooler temperatures, allowing its use • HIV-2 for a longer period of time after it had been collected from • Human T-lymphotropic virus (HTLV-1 and HTLV-2) a donor. The fi rst blood bank was created in anticipation of • Hepatitis B virus heavy casualties by U.S. Army physician Oswald Robertson • Hepatitis C virus when he collected and stored blood before the Battle of • West Nile virus Cambrai in World War I. Within 20 years, civilian blood banks • Treponema pallidum (causative agent of syphilis) began to develop in the United States and Europe. 600 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Blood Components Hematopoiesis is the manufacturing process the body uses to create the three main solid components of blood: red As the early microscopists discovered, whole blood is made blood cells (erythrocytes), white blood cells (leukocytes up of several components bathed in plasma (the liquid por- and lymphocytes), and platelets (thrombocytes). All three tion of blood). Scientists and physicians have studied blood of these major types of blood cells develop from the same over the last 400 years and have discovered the origin, struc- hemocytoblast (Figure 28-1), which is the generic stem cell ture, and function of these components. Each component has for blood cells. Blood cells are manufactured within the bone a unique function to carry out within the body. marrow of the long bones, pelvis, cranium, sternum, and Hemopoietic stem cell Rubriblast Myeloblast Monoblast Lymphoblast Megakaryoblast Prorubricyte Promyelocyte Promonocyte Prolymphocyte Promegakaryocyte Eosinophilic Neutrophilic Basophilic Rubricyte myelocyte myelocyte myelocyte Megakaryocyte Eosinophilic Neutrophilic Basophilic Large Metarubricyte metamyelocyte metamyelocyte metamyelocyte lymphocyte Metamegakaryocyte Eosinophilic Neutrophilic Basophilic Reticulocyte band cell band cell band cell Erythrocytes Eosinophils Neutrophils Basophils Lymphocytes Monocytes Thrombocytes Small T Small B Peripheral blood Granular leukocytes Agranular leukocytes Figure 28-1 Hematopoiesis is the production of the major blood cell types from the hemopoietic stem cell. Blood Products and Transfusion 601 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. vertebrae. The spleen, thymus, and lymph nodes are respon- blood cell if transfused into another person with a different sible for maturing certain white blood cells after production blood type. Blood compatibility is discussed more fully later in the bone marrow. in this chapter. Red blood cells, also known as erythrocytes, are small White blood cells, or leukocytes (Figure 28-3), func- doughnut-shaped cells which act to transport oxygen from tion as part of the immune system to react to foreign chal- the lungs to the cells (Figure 28-2). Hemoglobin, the com- lenges. There are three different subtypes of leukocytes— ponent of the red blood cell that binds to oxygen, is manu- basophils, neutrophils, and eosinophils—which react factured from iron. Each molecule of hemoglobin can bind against, and attach themselves to, certain types of infec- up to four molecules of oxygen. The physiology of oxygen tious organisms, whether bacterial, viral, or fungal. After delivery was discussed in Chapter 25. The surface of a red attaching to the foreign cells, these white blood cells blood cell contains proteins that produce antibodies to the red release toxic chemicals in an attempt to neutralize the invading organism. Macrophages are larger cells that attack and destroy the foreign invaders after the leukocytes iden- Red blood cells tify the foreign material. Another group of immune cells, called lymphocytes, are responsible for identifying foreign materials and developing antibodies against those foreign materials to allow enhanced immune system response dur- ing future infections. Platelets, or thrombocytes (Figure 28-4), are responsible for blood clotting. Platelets are attracted to a damaged blood vessel’s endothelium, the innermost layer of the blood ves- sel. Coagulation factors and other proteins attract other cir- culating platelets to the damaged area to build a plug that achieves hemostasis and stops bleeding from the damaged blood vessel. Coagulation factors are proteins which act to attract Figure 28-2 The erythrocyte. platelets to each other to build platelet plugs. Additionally, Granular leukocytes Basophil Neutrophil Eosinophil Nongranular leukocytes Lymphocyte Monocyte Figure 28-3 Leukocytes. 602 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Platelets Table 28-2 Normal Serum Blood Values Found in a Complete Blood Count (CBC) Component Normal Range Red blood cells 4.5–5.5 million per mL White blood cells 4,000–10,000 cells/mL Hemoglobin 13–16 g/dL (male) Figure 28-4 Platelets. 12–15 g/dL (female) Hematocrit 41%–50% (male) 36%–44% (female) coagulation factors are key to the production of fi brin and Platelets 100,000–450,000 platelets/mL fi brinogen, two materials that serve to solidify and stabilize the platelet plug, making it impermeable to liquid. The coag- Many of the blood components discussed are measured as ulation cascade (Figure 28-5) outlines the process the body part of a complete blood count (CBC) that is often performed uses to manufacture fi brin and fi brinogen. Most of the coagu- in the ED or physician’s offi ce (Table 28-2). The amount of lation factors are made in the liver, some of which depend on hemoglobin differs between males and females largely due vitamin K during the manufacturing process. Both congeni- to the females’ blood loss during normal menstrual cycles. tal and acquired defi ciencies of coagulation factors can cause The hematocrit measures the ratio between the volume of the diffi culty in clotting or spontaneous bleeding. solid components of blood compared against both its solid and Blood also has many other proteins that circulate liquid components, listed as a percentage (solid/total). throughout the system which serve multiple different func- tions. Some of these circulating proteins are the antibodies that help protect against infection, albumen that helps regu- Blood Products late blood volume, and hormones that act in a variety of ways Since the technique of fractionating blood into its individual on the body’s organs. The blood also transports nutrients and components was perfected in the 1950s and 1960s, transfu- other building block materials to the cells. sion of whole blood in civilian medicine has become uncom- mon. However, transfusion of whole blood is more frequent in the combat environment when large quantities of blood are Contact Activation Pathway required.2 The advantage of fractionating blood into its com- Activating ponents is more directed transfusion based on the patient’s factors specifi c needs as well as longer storage life for the compo- nents as opposed to whole blood. The four blood compo- 12 Tissue Factor Pathway nents most frequently transfused include packed red blood Activating cells (PRBC), fresh frozen plasma, cryoprecipitate, and 11 factors platelets. Packed Red Blood Cells 9 7 PRBCs are formed by removing nearly all of the plasma from a unit of blood and adding a small volume of preservative to the unit. PRBCs are often stored at near freezing temperatures 8 but can be frozen for longer-term storage. Each unit of blood 10 is approximately 250 mL in volume, which includes both the solid and liquid component of the unit. Assuming bleeding is 5 Common Pathway controlled and does not continue during the transfusion, each unit of blood is expected to raise the patient’s hemoglobin by 2 1 gm/dL.3 PRBCs are transfused primarily in the situation of acute Fibrinogen Fibrin blood loss (e.g., in bleeding from trauma or from gastroin- testinal bleeding). PRBCs are also transfused to patients who are anemic, those with a signifi cantly decreased hemoglobin Vitamin K dependent level, and those who have signs and symptoms of impaired factors oxygen delivery (e.g., dyspnea, lightheadedness, or chest Cofactors pain). Anemic patients with known cardiac disease may also be transfused to ensure suffi cient oxygen delivery and pre- Figure 28-5 The coagulation cascade. vent cardiac events due to each patient’s anemia. Each unit Blood Products and Transfusion 603 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. of PRBCs can be transfused in as little as several minutes Platelets in critically ill, hypotensive patients with acute blood loss, Platelets are separated from plasma in the blood bank by one and up to two to four hours for patients who have poor car- of two methods. In order to raise the patient’s platelet count diac function. Most often, PRBCs are transfused at a rate of by 50,000 platelets, the patient needs to receive approximately approximately one unit per hour to two hours. However, in six units of platelets, which can be a signifi cant amount of severely hypotensive patients, a unit of PRBCs can be trans- volume. Each unit of platelets should be transfused over a 30 fused in a matter of minutes. to 60 minute time period. The indications for platelet transfu- At times, the patient requires so much blood that addi- sion vary based upon the patient’s platelet count, presence tional blood components are required. The term “mas- of bleeding, or risk of bleeding with a planned procedure. sive transfusion” is used to describe a situation in which Platelets are often transfused in patients undergoing massive a patient has signifi cant ongoing blood loss to the point transfusions as they are usually defi cient in platelets. Platelet where one to two body volumes of blood are required. transfusions may not be effective in conditions where platelet For the average weight person, this translates to a transfu- function is decreased (e.g., in renal disease).4 sion of 10–20 units of PRBCs. In situations in which the total blood volume needs replacement, other components which are absent in PRBCs—including platelets and coag- Blood Groups and Compatibility ulation factors—will also need to be replaced in order to Early transfusions caused reactions in an inconsistent man- prevent continued bleeding due to loss of the blood’s clot- ner. Some transfusions occurred without problems. In others, forming ability. the recipient had severe and sometimes fatal reactions. It was not until the early 1900s that a physician researcher, Dr. Karl Fresh Frozen Plasma Landsteiner, discovered that red blood cells have proteins Fresh frozen plasma (FFP) is formed by removing the red on the cell’s surface that are responsible for producing some blood cells and platelets from whole blood. The remaining transfusion reactions. This section will discuss the concept of liquid component of the blood is still rich in several of the blood grouping and matching donor blood to the recipient. clotting factors needed as part of the coagulation system. Two of these key coagulation factors are factors V and VIII. One Blood Grouping unit of FFP has a volume of approximately 200 mL and is The proteins that exist on the surface of the red blood cells transfused in 30 to 60

minutes. help the body identify which cells are its own cells as opposed FFP is most often used to treat clotting disorders which to foreign invaders. If a donor has different proteins on the accompany several diseases that include decreased clotting surface of donated blood products, the recipient’s immune factor production (e.g., liver disease). FFP is also used to system will identify those components as foreign material, treat patients who have taken an overdose of the anticoagu- and set off an immunological chain reaction that will lead to lant warfarin because of its action in inhibiting the production the clumping together of red blood cells, called agglutina- of clotting factors. FFP is also used to treat a condition called tion. The clumping causes the red blood cells to break apart, disseminated intravascular coagulation, in which the clotting a process called hemolysis (Figure 28-6). factors are rapidly used up and the patient develops bleeding Dr. Landsteiner identifi ed the existence of two proteins—an because of the clotting factor defi ciency. A protein and a B protein—on the surface of red blood cells. Red blood cells that have the A protein on the surface are called Cryoprecipitate Type A blood. If the B protein is present on the surface of the red Cryoprecipitate is the protein portion of plasma made up of blood cell, the blood is Type B blood. He also noticed that some concentrated clotting factors in a much smaller volume than red blood cells do not have either an A or a B protein on the FFP. One unit of cryoprecipitate has a volume of between 25 surface. Cells without these proteins were called Type O blood. and 50 mL, much less than one unit of FFP. Cryoprecipitate is The A-B-O designations formed the fi rst system of determining transfused between 15 and 30 minutes per unit. Cryoprecipitate blood type. At a later time, it was observed that some red blood contains factors V, VIII, and XIII. Additionally, cryoprecipi- cells have both an A and a B protein on their surface, and thus tate contains fi brinogen and fi bronectin, proteins that help the blood type is called Type AB blood, the fourth major blood solidify a clot, and von Willebrand factor, which helps to ini- group in the A-B-O typing scheme (Figure 28-7). tiate clot formation. These surface proteins are also antigens, meaning that Cryoprecipitate is indicated in overanticoagulation or they can produce an immune system response. Patients with disseminated intravascular coagulation. It is also indicated in Type A blood have antibodies against Type B blood in their patients who have hemophilia A or von Willebrand’s disease plasma. Conversely, patients with Type B blood have antibod- who are bleeding, as it quickly replaces the defi cient factor. ies to Type A blood in their plasma. Patients who have Type Cryoprecipitate is also used when patients are receiving a O blood have antibodies to both Type A and B blood in their massive transfusion to replace coagulation factors that are system and patients with Type AB blood do not have any of lost and not present in PRBC units. these antibodies in their system. As previously described, 604 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. + Figure 28-6 Agglutination and hemolysis occur when cells of incompatible blood types are mixed together. A B Table 28-3 The Frequency of Blood Type A antigen B antigen in the United States Based on the A-B-O and Rh Systems5 A-B-O and Rh Frequency O 37.4% B antibody A antibody O 6.6% A 35.7% AB O B antigen A 6.3% B 8.5% B 1.5% A antigen A antibody AB 3.4% B antibody AB 0.6% Figure 28-7 The major red blood cell types. Table 28-4 Examples of the 29 Different Blood Grouping Systems Recognized by the ISBT these antibodies are responsible for the agglutination and • A-B-O hemolysis of foreign blood cells. • Rh Dr. Landsteiner also discovered a second protein that • MNS existed along with the A and B proteins. This protein, the Rh factor, was named after the Rhesus monkey, whose blood • Lewis was used for the experiments that led to the discovery of the • Duffy Rh factor. The Rh factor is either present or absent, which • Kidd is denoted by adding a plus () or minus () to the A-B-O • Diego type. Patients with Rh blood do not have antibodies against • Cartwright the Rh protein; however, some patients with Rh blood have developed antibodies against the Rh protein and can develop a transfusion reaction. Between these two typing systems, the recipient’s and donor’s blood, the more compatible they there are eight major blood types that exist (Table 28-3). are and the less likelihood of severe transfusion reaction. As In addition to the major A-B-O and Rh blood types, previously discussed, blood of a certain type will often have the International Society of Blood Transfusion (http://www antibodies present that attack other types of blood. A recipi- .isbt-web.org/) recognizes a total of 29 different groups used ent may be able to safely receive other types of blood if the for blood typing. The 27 other typing schemas were classifi ed recipient’s type of blood is not available (Table 28-5). Notice by identifying other minor proteins that occur on the surface that Type O blood can be given to any of the A-B-O blood of blood cells which also cause immunological reactions when types because Type O blood does not have surface proteins different types of blood are mixed together (Table 28-4). that incite the immune response which ends in hemolysis. Compatability Type O blood is sometimes termed the universal donor due to this property. In contrast, patients with Type AB blood can As blood grouping was discovered and testing became avail- receive blood from any donor because the patient does not able, every effort was made to decrease the likelihood of a have antibodies against A or B proteins present in the plasma. severe transfusion reaction by matching the recipient’s blood Due to this property, individuals with Type AB blood are with potential donor’s blood. The greater the match between called universal recipients. Blood Products and Transfusion 605 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Table 28-5 Who Can Receive What Blood Types? same A-B-O and Rh types as the recipient’s blood, even If the Recipient Has Type: The Recipient Can Receive: though it has not been completely cross-matched. This often occurs when blood is required emergently while the A blood Type A and O blood blood bank is in the middle of the cross-matching process. B blood Type B and O blood All efforts to use cross-matched blood for subsequent units O blood Type O blood only of blood products are made once the uncross-matched or AB blood Type A, B, AB, and O blood only type-specifi c blood is used on a patient. Patients receiving Rh blood Type Rh or Rh blood uncross-matched or type-specifi c blood must be monitored Rh blood Type Rh blood only closely for transfusion reactions. Identifi cation and Management Cultural / Regional differences of Transfusion Reactions Transfusion reactions vary from minor to life-threatening. Some religious groups refuse blood transfusions due The Paramedic must be able to confi dently identify and treat to their belief that it is specifi cally forbidden. Courts the wide range of potential transfusion reactions that may have been asked to order blood transfusions in cases occur during transfer. of vulnerable populations such as children. Overruling a patient’s or family’s religious beliefs is not done Street Smart lightly. Some transfusion reactions can occur with as little Transfusion Terms as 10 mL of blood transfused. However, most tend to occur by the time the fi rst unit has fully transfused. Several terms are used to refer to the different blood products regarding their types and compatibilities. It is important for the Paramedic to understand these terms as it may impact the Transfusion-Associated transfusion process. Circulatory Overload During this process, which typically takes a half hour to accomplish, the blood bank uses a sample of the recipient’s Transfusion-associated circulatory overload (TACO) occurs blood and identifi es antibodies present in the sample. Using when the patient receives more volume of blood products than this information, the blood bank can fi nd a blood match that can be handled by the circulatory system. This overload essen- does not have antigens which will react with the antibodies in tially produces pulmonary edema and is more likely to occur in the recipient’s blood. In some cases, the recipient has numerous patients with impaired cardiac function, including the elderly, antibodies present in the blood and a prolonged time is required those with underlying CHF or coronary artery disease, or pedi- in order to identify blood for transfusion. In more complicated atric patients. It is important to note that a signifi cant amount cases, suffi ciently matched blood may need to come from of volume is infused into any patient, including those who are another center or blood bank in order to be safe for transfusion. healthy with normal heart and kidney function, and that TACO Donor blood that is successfully matched to recipient blood is can develop. As previously discussed, each unit of PRBCs is called type and crossed or type and cross-matched blood. a volume of 250 mL. Blood products are always run together In some cases, there is insuffi cient time to complete a with a second saline infusion running at a to-keep-open rate cross-match of recipient and donor blood. In cases of severe so the intravenous line does not clot off at the end of the trans- shock from acute blood loss (e.g., trauma, gastrointesti- fused unit. In addition to the 250 mL in the unit of blood, up to nal bleeding), a patient may require an immediate blood another 100 mL of normal saline is infused per unit of blood transfusion in order to sustain life. In these cases, uncross- product. As most critically ill patients requiring transfusion are matched blood is transfused using either O or O donor given several units of blood or blood products, it is easy to pro- blood that does not undergo the usual cross-matching pro- vide a signifi cant amount of volume in a short period of time. cedure. In general, O blood is preferred for women of To address this issue, patients at risk of circulatory overload childbearing age to avoid the development of antibodies to should be transfused at a slower rate than normal. Rh blood that may be transfused into the recipient with an unknown blood type. This is important because during Allergic Reaction a subsequent pregnancy, the maternal antibodies can attack Allergic reactions can occur due to MAST cell activation in the fetal blood cells, potentially resulting in fetal death. the recipient’s blood once exposed to the donor’s blood, and In some cases, the patient’s blood type is known and it are seen in up to 1% of transfusions.6 The allergic reactions is possible to administer type-specifi c blood that has the can range in severity from a mild reaction that includes itching 606 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time

if subsequent rights restrictions require it. or some hives to anaphylaxis and airway edema. Most allergic every 500,000 units of PRBCs.7 The higher incidence of bac- reactions of this type will resolve spontaneously. Some reac- terial contamination of platelets is due to the higher tempera- tions will require administration of medications or slowing of ture at which platelets are stored. Contamination is rarely due the transfusion. Severe allergic reactions will defi nitely require to an illness in the donor. More often, it is due to contamina- medication treatment and may require airway management. tion which occurred during the collection or storage process. The patient may become septic due to the contamination, Febrile Non-Hemolytic Reaction though most often the patient exhibits signs of an infection, Febrile transfusion reactions are defi ned as an elevation of the including fever, chills, and rigors. Patients may also develop patient’s temperature of 1°C from baseline within two hours of dyspnea, hypotension, nausea, vomiting, or diarrhea. the start of the transfusion.6 A febrile non-hemolytic reaction more often begins shortly after the initiation of the transfusion or Transfusion-Related a new unit and is often secondary to minor antibodies present in Acute Lung Injury the recipient’s blood that cause a mild reaction when exposed to Transfusion-related acute lung injury (TRALI) is defi ned the donor’s blood. In addition to fever, the patient may develop as a new acute lung injury that occurs within six hours of chills, rigors, headache, nausea, or vomiting. The fever may a transfusion and is directly related to the transfusion.8 The resolve spontaneously, but often an antipyretic (e.g., acetamino- patient develops hypoxemia, dyspnea, and bilateral infi l- phen) is administered to treat the symptoms. If the fever persists trates that can be best seen on a chest x-ray in the ED but or elevates, the transfusion may need to be stopped. may produce bilateral rales (crackles) on auscultation by the Paramedic. TRALI occurs as a result of pulmonary capillary Acute Hemolytic Reaction leakage of plasma into the tissues surrounding the alveoli in An acute hemolytic reaction is one of the most serious the lung. It is believed that TRALI is set off by antibodies transfusion reactions and most often occurs as a result of against white blood cells present in the donor’s blood that an A-B-O incompatibility (Table 28-6). In other words, an react with the recipient’s white blood cells. Less frequently, incorrect blood type was administered to the patient; for the recipient’s blood contains the antibodies that attack white example, Type A blood was administered to a patient who blood cells that may be present in the donor unit of blood. has Type B blood. This produces agglutination and hemolysis The antibodies set off an infl ammatory reaction that produces of the transfused blood. The hemolysis may involve native compounds with the end result of leakage of plasma from red blood cells. Around 10% of patients who are exposed to the pulmonary capillaries. Alternatively, other infl ammatory A-B-O incompatible blood die of the hemolytic reaction. proteins may be present in the donor’s blood that causes the The administration of the wrong type of blood to a patient infl ammatory reaction in the recipient’s lungs (Table 28-7). can occur for several reasons, and an entire system of checks While TACO and TRALI may be diffi cult to differentiate in and balances has been developed in order to minimize these the fi eld, TACO tends to produce a more frank pulmonary errors. It is of the utmost importance that the Paramedic take edema, whereas TRALI produces fi ner rales (crackles) with- on a personal responsibility to ensure that any units of blood out a signifi cant fl uid overload. products that are transported with the patient are correctly labeled. The procedure will be discussed further in a later Treatment of Transfusion Reactions section of this chapter. Ultimately, if the transfusion contin- Regardless of the transfusion reaction identifi ed by the ues, the patient can develop shock, renal failure, disseminated Paramedic, the fi rst key step is to stop the transfusion, change intravascular coagulation, and death. the tubing, and fl ush the line with normal saline. These actions will prevent a continued reaction to the blood product. The Bacterial Contamination unit of blood product and the line must be saved and given to Bacterial contamination of blood products is estimated to the blood bank at the receiving hospital for testing. Draw a occur at a rate of 1 in every 15,000 units of platelets and 1 in red or pink top tube from the patient for testing by the blood bank at the receiving hospital. The blood bank at the receiv- ing hospital will retest both the donor unit and the sample Table 28-6 Signs and Symptoms of an Acute Hemolytic Transfusion Reaction • Fever > 2°C above the patient’s baseline temperature Table 28-7 Signs and Symptoms of TRALI • Hypotension • Dyspnea • Dyspnea • Tachypnea • Pain at the site of the transfusion, back, and chest • Cyanosis • Hemorrhage and/or hemoglobinuria (dark-colored urine) • Fever • Nausea and vomiting • Tachycardia • Jaundice and icterus • Froth in the endotracheal tube Blood Products and Transfusion 607 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. from the recipient to ensure there is a match and identify any Table 28-8 Items to Confi rm Prior to Transport cross-matching errors. Contact on-line medical control to discuss the specifi c patient and develop a treatment plan as • Verify patient identity well as to decide whether to continue the transfusion. • Verify consent for transfusion or indication of reason for implied Administer supplemental high-fl ow oxygen if the patient consent is not already on supplemental oxygen. For the patient who • Verify the patient’s blood type (A-B-O and Rh) develops an allergic reaction, administer diphenhydramine • Verify transfusion orders: and methylprednisolone intravenously to treat the aller-  Type of blood product gic reaction. For anaphylactic reactions with hypotension,  Rate of administration severe dyspnea, or throat edema, administer epinephrine  Order of administration (if multiple products) intramuscularly to treat the anaphylaxis. TACO is treated • For each unit hanging or carrying during transport, verify with by administering furosemide intravenously and applying another Paramedic, RN, physician, or mid-level provider: CPAP to support ventilation and off-loading of fl uid from  Blood type of unit the lungs. Patients who develop TRALI will often require  CPAP or intubation. Care is supportive and does not require Rh factor of unit medications.  Patient ID label  Unit expiration date Transfusion Procedure  Donor unit number and patient information match and Documentation Having reviewed the different types of blood products and the indications for transfusion and transfusion reactions, the next section discusses the procedure for blood product trans- Street Smart fusion. These steps must be followed with every unit trans- fused. Remember, there is a mortality rate of 10% for patients The Paramedic should document what items were who receive mismatched blood products regardless of treat- verifi ed and with whom on the regular patient care ment. This is a very serious complication of blood product transfusion. record in addition to completing the blood bank record. Street Smart During the Transfer Blood is transfused through one of two types of administra- Hyperkalemia may occur due to infusions with tion sets. The blood transfusion set is preferred over the pig- gyback set (both described in Chapter 27) because the blood irradiated red blood cells. Hypocalcemia may administration set has a larger lumen, providing less resis- result from multiple transfusions due to the citrate tance to fl ow than a piggyback setup. The second advantage preservative binding serum calcium and is indicated of blood tubing is that both ports of the “Y” shaped tubing fl ow into the same drip chamber, allowing less resistance to by circumoral tingling and tremors. fl ow for the normal saline that is administered with the blood. Normal saline should be set to run at “to-keep-open rate” so Prior to Transfer it fl ushes the line with saline after the unit of blood product is fi nished. During the patient report received from the RN in the send- During transport, blood products must be stored in an ing facility, the Paramedic needs to confi rm several items appropriate transport cooler that is certifi ed by the blood bank before receiving the patient and blood products (Table 28-8). (Figure 28-8). This is essential as most blood products should These steps are important to ensure that the blood products be stored at a temperature between 1°C and 6°C. The shelf match the patient’s A-B-O and Rh factor and that only blood life of a unit of blood at room temperature is approximately products intended for that specifi c patient are transfused. 30 minutes. Warmer temperatures increase the risk of bacte- Ideally, the transfusion will have been initiated in the send- rial contamination as well as developing proteins in the donor ing emergency department and the patient monitored for 15 blood that can initiate transfusion reactions. to 30 minutes in order to identify major transfusion reactions The Paramedic should record vital signs, including tem- before transport. Review the pre-transfusion set of vitals, perature, at 15-minute intervals during transfer. Vital signs including a temperature, as some of the transfusion reactions should also be recorded after completing each unit. The rely on a change from baseline temperature in identifying Paramedic should auscultate the patient’s lungs between the reaction. units to identify signs of fl uid overload. This is especially 608 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Street Smart The Paramedic should evaluate the patient’s skin each time vital signs are obtained for indications of an allergic reaction. After the Transfer The Paramedic must document at a minimum vitals, times, reactions, and information about the blood products admin- istered to that patient during transfer. This information may be documented on a usual patient care report or a specifi c special form may be required. The Paramedic should use the specifi c form required by her agency. One copy of the transfusion record should be left at the receiving hospital and Figure 28-8 A transport cooler certifi ed by the another copy kept with the prehospital documentation. blood bank. (Courtesy of Thermosafe Brands, a Strategic Any unused blood products should be given to the blood Business Unit of Tegrant Corporation) bank at the receiving hospital. The blood is then retested and either used for the transferred patient or made available for others who match that donor’s blood. In the event of a transfu- important in intubated or sedated patients as they may not be sion reaction, the unit of blood that was hanging at the time of able to complain of dyspnea. A fi nal set of vital signs should the reaction, the blood tubing, and the patient’s blood sample be recorded on arrival to the receiving facility. should be brought to the blood bank for testing. Blood Products and Transfusion 609 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. The transfusion of blood products during critical care transport by the Paramedic can provide a life-saving therapy to the critically ill patient who requires

blood products. It is important for the Paramedic to approach blood transfusions methodically and systematically in order to ensure patient safety during the transfusion. It is also critical to continuously monitor the patient during transfer so as to identify and treat transfusion reactions early. Key Points: • Refi nements in the process of giving blood from one • When no further blood loss occurs, a unit of packed red animal to another, and ultimately from one human cells will increase the hemoglobin levels by 1 gm/dL. to another, has been ongoing for over 400 years. • Fresh frozen plasma (FFP) is formed by removing cells • Blood groups are identifi ed by specifi c antigens from whole blood and is rich in several of the clotting located on the red blood cell. factors needed as part of the coagulation system. • Other proteins also affect blood compatibility. • Cryoprecipitate is the protein portion of plasma made up of concentrated clotting factors. • Donated blood is tested for multiple infectious diseases. • Platelets may be transfused in patients undergoing massive transfusions. • Whole blood consists of solid components (red and white blood cells plus platelets) and plasma. • There are eight major blood types: ■ Type O positive or negative • Hematopoiesis is the process that the body uses for ■ Type A positive or negative the development of solid blood components. ■ Type B positive or negative • ■ Type AB positive or negative All blood cells develop from a hemocytoblast. • Blood cells are manufactured within the bone • Type O blood is called the universal donor as it does not have surface proteins that trigger an marrow of the long bones, pelvis, cranium, immune response. sternum, and vertebrae. • • Type AB is called the universal recipient as there Red cells transport oxygen. are no circulating antibodies capable of attacking • White cells are part of the immune system. A or B red cells. • Platelets are a part of the blood clotting process. • The process of determining blood compatibility between the recipient and donor blood is called • The coagulation cascade, using multiple factors, cross-matching. leads to the development of fi brin, a blood clot. • Transfusion reactions vary from minor to life- • Normal hemoglobin amounts vary from males to threatening. females. • Treatment depends on the type of reaction. • Hematocrit compares the ratio of solid components • Prior to transfer, verify pertinent details regarding of blood to the volume of blood. the patient and the blood products. • The four blood components most frequently • Blood may be transfused via a “Y” shaped blood transfused include packed red blood cells (PRBC), administration set or a piggy back system. The fresh frozen plasma, cryoprecipitate, and platelets. blood administration is the preferred method. 610 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. • Blood must be kept cool to reduce the risk of • The transfusion record must be completed after reactions. each unit of blood product. • The patient should have vital signs taken every 15 • Any blood product and tubing involved in a minutes during transfusion. transfusion reaction should be brought to the blood bank at the receiving hospital. Review Questions: 1. What determines a blood group? 7. What four blood products are routinely 2. Name the blood groups. transfused (not necessarily to the same 3. What is a universal donor? Universal recipient? patient)? How do they differ from each other? How are antigens and antibodies involved in 8. Defi ne hemoglobin. Defi ne hematocrit. these designations? 9. Name each transfusion reaction and list its 4. What are the solid components of prehospital treatment. the blood? 10. What items should be verifi ed before transport? 5. What is the process by which the solid 11. How often should the patient be assessed components of blood are formed? Where are (minimally)? they formed? 12. Describe the process of completing a blood 6. What is the liquid portion of blood called? transfusion including its documentation. Case Study Questions: Please refer to the Case Study at the beginning of 3. What blood components is this patient likely the chapter and answer the questions below: receiving? Explain your answer. 1. How are blood transfusions managed? 2. What complications can occur during transfusion? References 1. Schreiber GB, Busch MP, Kleinman SH, Korelitz JJ. Risk of 5. Stanford School of Medicine Blood Center. Blood types in the transfusion-transmitted viral infections. N Engl J Med. June 27, U.S. Available at: http://bloodcenter.stanford.edu/about_blood/ 1996;334(26):1685–1690. blood_types.html. Accessed October 31, 2008. 2. Kauvar DS, Holcomb JB, Norris GC, Hess JR. Fresh whole blood 6. Santen SA. Transfusion therapy. In: Tintinalli JE, Kelen GD, transfusion: a controversial military practice. Journal of Trauma. Stapczynski JS, eds. Emergency Medicine: A Complete Study 2006;61(1):181–184. Guide (6th ed.). New York: McGraw Hill; 2004:1348–1353. 3. Department of Medicine, Washington University School 7. Nester T, Lopez-Plaza I. Bacterial contamination of cellular blood of Medicine. Chapter 19: Anemia and transfusion therapy. products. Transfusion Medicine Update. Epub February 2001. Washington Manual of Medical Therapeutics. 2007. Available at: http://www.itxm.org/TMU2001/tmu3-2001.htm. 4. Wittler MA, Hemphill RR. Acquired bleeding disorders. In: Accessed October 28, 2008. Tintinalli JE, Kelen GD, Stapczynski JS, eds. Emergency 8. Toy P, Popovsky MA, Abraham E, et al. Transfusion-related acute Medicine: A Complete Study Guide (6th ed.). New York: McGraw lung injury: defi nition and review. Critical Care Medicine. Hill; 2004:1324–1329. 2005;33(4):721–726. Blood Products and Transfusion 611 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. KEY CONCEPTS: Upon completion of this chapter, it is expected that the reader will understand these following concepts: • Pharmacology as a study of drug treatments • Regulation, classifi cation, and referencing of drugs • New drug development and public safety • Mechanisms of action • Special considerations of the pregnant, pediatric, and geriatric patients Case Study: Katie O’Rielly had fallen from her bike while trying some tricks on her brother’s homemade skateboard ramp. While the junior Paramedic partner completed the assessment and obtained vital signs, his senior partner called for medication orders. After reporting that Katie was 7 years old, had signifi cant deformity to her left wrist and forearm, and had no allergies (according to her dad), the Paramedics relayed Katie’s vital signs, weight, and pain scale. After completing Katie’s care, which included some IV pain medication and medication to prevent nausea, the Paramedics transferred her to the hospital and began completing their paperwork. “Have you administered narcotics with this agency as yet?” asked the senior Paramedic. “There are very specifi c procedures and paperwork to complete.” 612 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Introduction to Pharmacology 613 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. OVERVIEW Pharmacology has its origins in medicinal treatments used to restore humoral balance to the body. As experience and experimentation pushed forward, the paradigm shifted from humoral imbalance to the idea that illness is caused by disease. This chapter will outline how drugs are classifi ed, regulated, and developed as well as how the Paramedic may reference an unfamiliar medication. Becoming familiar with pharmacology also requires the Paramedic to understand basic pharmacokinetics and how drugs are absorbed, distributed, detoxifi ed, and eliminated from the body. Just as important as understanding how a drug moves through the body is how a drug specifi cally works upon a cell. Pharmacodynamics helps to explain how drugs create their therapeutic effect and helps the Paramedic to understand a drug’s mechanism of action. Presented throughout the chapter are the special considerations that apply to administering drugs to pregnant, pediatric, and geriatric patients. Paramedic Pharmacology term “pharmacy” comes from the Greek word “pharmakos,” which can be translated to mean either “to remedy” or “to Drugs have had, and continue to have, a dramatic impact on life. poison.” It is imperative that all Paramedics understand the In 1901, the average American could expect to live to be about actions of these medications and their potential for harm 49 years old. One hundred years later, the average American before administering them. can expect to live to be at least 78 years of age.1 A number of factors, such as safer working conditions, improved nutrition, cleaner water, better sanitation, and the advent of potent medi- Historical Development cations, have led to this dramatic increase in life expectancy. of Pharmacology In addition, great medical breakthroughs have dramatically improved the quality and duration of life (Table 29-1). In 1889, Sir Petri discovered an Egyptian papyrus written in Advances in safety and ease of administration of pharma- 1900 B.C. that described the treatment of a “falling womb” cological agents, as well as the advantage of early intervention with a gruel made of cool milk and grain. Believed to be the in acute medical emergencies, has prompted emergency physi- oldest written prescription, it represented the timeless effort cians to promote the use of these medications by Paramedics. of people to rid themselves of disease. Throughout world his- Today, Paramedics carry some of the most powerful drugs tory, continuous discoveries and advancements in the use and available in medicine. These medicines are capable of sav- creation of medications have taken place. Many medications ing a life when used appropriately. However, these drugs are have revolutionized the practice of medicine. equally capable of causing death if given without due regard Some of the earliest accounts of medication use came to their mechanism of action and possible side effects. The from the work of priests in the temple of Asclepius (the Greek God of healing). Here priests would instruct patients on a variety of treatments, ranging from the application of poultices made of herbs to the use of charms to frighten evil Table 29-1 Major Medical Breakthroughs spirits. Each attempt to use medications was met with vary- 1796 Vaccines ing degrees of success, with the outcome more likely to be 1865 Antiseptic poor than good. Most people felt that illness was created by 1895 X-ray the gods or was the result of evil spirits. Therefore, it was 1897 Aspirin 1905 Vitamins believed that illness was inevitable and, more importantly, 1922 Insulin immutable to physician interventions. 1929 Antibiotics 1933 CPR 1953 Polio Street Smart 1960 Pacemaker 1967 Heart transplant 1972 Medical fi lming Asclepius, the Greek God of healing, was thought to 1980 Smallpox hold the serpent as sacred. His symbol, a staff with a 1982 Artifi cial heart 1990 Human genome coiled snake around the shaft (known as a caduceus), 1997 Cloning is now used as a symbol of medicine. 1998 Stem cell research 614 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that

any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Hippocrates (460–560 B.C.), a member of the healing theory, publicly burned copies of Galen’s writings and guild Asclepiadae named after the god Asclepius, is consid- Avicenna’s “materia medica,” and suggested instead that ill- ered the “father” of western medicine. Hippocrates advanced ness was caused by disease. He believed that disease could be the idea that disease was not caused by evil spirits but rather treated with mineral baths of mercury, arsenic, lead, or cop- by natural causes, i.e., an imbalance in the body. Imbalances per and alcoholic extracts, formulas of which he added to the in the “humours” contained within the body was a revolution- pharmacopeia.4 This idea, that illness was caused by disease, ary idea in its time.2,3 was a radical departure from the theory of humoral imbal- These humours were red blood, white phlegm, yellow ances. It suggested that, with experience and experimenta- bile, and black bile, each representing the fundamental ele- tion, medications could lead to the cure of disease. Paracelsus ments of air, water, fi re, and earth. Hippocrates also believed was credited with establishing the scientifi c method in his in the recuperative powers of the human body and felt that study of medicine, a practice that continues even today. medicine could help to support the body’s efforts at bringing In the centuries that followed, medicine made great strides itself into balance from “humoral pathology.” toward relieving suffering and curing disease through the use Some of the most important advances in medical prac- of drugs and herbal remedies. Widespread experimentation tice during that time are credited to Galen, a physician to the with these new formulas in order to create new remedies her- gladiators and later court physician to Commodus, the son alded the dawn of pharmacology, the study of drugs. of Marcus Aurelius. Galen wrote volumes about medicine In the early 1600s, the fi rst London pharmacopeia was and established a system of medicinal practice that remained compiled. This was followed in 1618 by creation of the fi rst intact until after the Dark Ages. He wrote of the nature of national pharmacopeia, the French Codex. Thereafter, many pulses and described certain “ores” and potions of medicinal national pharmacopeias were compiled. Drugs, as a commod- value, including the “balm of Gilead,” a juice-balsam. ity, were then traded from city to city and country to coun- After the time of Hippocrates and Galen, the science of try since these national pharmacopeias allowed free trade of medicine developed along several different paths. Although similar drugs. With the widespread availability of the drug the contributions early Chinese and Indian practitioners information contained within these national pharmacopeias, made to the science of medicine were signifi cant, the focus of pharmacies began to appear in marketplaces all over Europe. medicine in the western world lay along the paths created by Exact formularies also allowed industries to be developed for Hippocrates and followed by Galen. However, the Arab world the mass production of medicine. Thus, medications began was to have a great infl uence on western medicine as well. to become more widely available to the public. Examples of Arabic medicine, practiced from the fertile crescent of Persia these early medications include tincture of opium, used to to the south of Spain, made signifi cant advances, particularly treat diarrhea (a common malady in a time when dysentery in pharmacy. This was due in part to the introduction of arith- was rampant), and syrup of ipecac, used in presumed poison- metic, which allowed addition and subtraction in measure- ings to prevent illness.5 ments of raw materials and substances. Early Arabic infl uence in medicine was seen in the writ- Sources of Drugs ings of Ibn Sina (Avicenna), physician-in-chief in Baghdad. He wrote volumes about medicine, 290 manuscripts in total, When pharmacy was in its infancy, most medications came including his treatise on medicine entitled Kitah al-Qanun from plants. Advances in pharmacy and chemistry resulted in (translated The Medical Code). He was second only to Galen the development of new sources for drugs, including drugs in his infl uence on western medical thought. Ibn Sina’s fi ve- from animal by-products, minerals, synthetic medicines, and, volume Kitah al-Qanun arranged medical knowledge by sub- most recently, genetic engineering. ject, described some 760 drugs alphabetically, and described diseases and their treatment.4 Plants Later, in the sixteenth century, pharmacy was to be further Early pharmacists would take the roots, fl owers, and seeds of advanced by a German botanist named Valerius Cordus who a plant; crush them; mix them together in different amounts, wrote the fi rst authoritative collection of formulas of drugs or formulas; and create crude drugs. While many of these called a “pharmacopeia.”5 A pharmacopeia, also called a herbal concoctions were impure and impotent, some had compendium, is a comprehensive list of drugs which not only active ingredients which had an intended or therapeutic includes formulas but usual strengths, standards of purity, effect. The bark of the willow tree, for example, was used and ranges of doses that are available in a certain country or as a cure for a number of ailments including headaches. It region. By creating “drug standards”—specifi cations for the contains the active ingredient salicylate, which is still used mixture of minerals, chemicals, and biological materials—a in aspirin today. large number of deaths secondary to accidental overdose While most medications are chemically manufactured were avoided and the effects of specifi c ingredients upon the today, plants are still an important source of many medicines. body were better understood. Many of the essential plant elements of crude drugs are more At about the same time, a physician named Paracelsus highly refi ned, making them more potent, and they are manu- (1493–1541) denounced Hippocrates’ “humoral pathology” factured in mass quantities. Plant derivatives used to make Introduction to Pharmacology 615 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. drugs can be grouped together according to common physi- cal or chemical properties. These organic-based groups are Street Smart alkaloids (glycosides), oils, and gums. The Alkaloids The antibacterial action of common household bleach The alkaloids, as the name suggests, are nitrogenous chemi- solution (Sodium hypochlorite 5%), used in EMS to cals which are alkaline in nature and often chemically com- clean surfaces contaminated with blood, is due to bined with acids to create water-soluble salts, such as morphine the off-gassing of hypochlorous acid from chlorine sulfate or atropine sulfate. When these alkaloids are absorbed in water. The resulting chlorine gas is toxic to most into the body they dissolve easily. The acid and alkaline com- ponents dissociate and the alkaloid drug can be transported in bacteria. the bloodstream and eventually deposited at the target organ, where it can produce its intended therapeutic effect. One of the earliest drugs obtained from a plant was digi- Animal talis. Digitalis, a cardiac stimulant found in the nightshade Many drugs have their origins, in whole or in part, from plant, was used to treat a cardiac condition referred to then as animal tissues. The discovery of insulin is a case in point. dropsy, which is now known to be congestive heart failure.6 Diabetes mellitus is a disease that causes the patient to excrete The active ingredient in plant-based drugs like digitalis is massive amounts of thick syrup-like urine. The resulting side-linked to a simple sugar, a glucose molecule, in the plant. diabetes-induced dehydration can lead to severe shock. In Thus, it is called a glycoside. Glycosides are easily absorbed the summer of 1921, Fred Banting noted that an injection of into the bloodstream and the active ingredient is taken up by extract from the pancreas of animals, specifi cally the islets the target organ when the sugar is absorbed. of Langerhans, reversed the ill effects of the diabetes and allowed the patient to return to a near-normal life. That extract The Oils was fi rst called isletin and then later insulin. Sir Frederick G. Oils are substances that have been extracted from plants for Banting, MD, won the Nobel Prize for his discovery of insu- centuries for their use as food additives as well as medica- lin. Shortly thereafter, the Eli Lilly Drug Company began to tions. An example is olive oil. Some plant-based oils have mass-produce insulin, which it extracted from the pancreas of medicinal properties. For example, caster oil is used as a lax- cows (beef insulin) and pigs (pork insulin). This resulted in ative. Oils that give off an odor are called aromatic oils. The improved lives for many diabetic patients. Many other drugs, aroma is caused by volatile chemicals that evaporate, or off- such as epinephrine (adrenaline), were discovered in similar gas, into the atmosphere. These aromatic oils are often used fashion and the study of “organotherapy” fl ourished in the as fl avoring essences for medicine (e.g., oil of peppermint) or late 1800s.5 as soothing topical astringents, such as oil of spearmint. Synthetic The Gums One of the diffi culties of manufacturing animal-based drugs The gum of a plant, sometimes called its resin, is actually was the pure volume of animal tissue that was sometimes a complex sugar, a polysaccharide, that when moistened needed to create them. For example, only one-half ounce of becomes a gelatinous material. Complex sugars are also corticoid steroid could be distilled out of one ton of cows’ called colloids because they are too large to pass through adrenal glands.7 Drug manufacturers had a tremendous hur- a semipermeable membrane. When a gum is swallowed, it dle to overcome to produce these drugs profi tably. swells because of osmosis, forming a gelatinous bulk. This In the 1940s, a basic building block of human hormones property is useful when a laxative effect is desired. Applied was discovered as naturally occurring in wild Mexican yams. externally, certain gums help to soothe irritated skin. These yams could be transformed, with chemical process- ing, into the female hormone progesterone. That discovery Minerals, Chemicals, and Salts (using select plant stuffs and chemically processing them to Natural salts and minerals have also been used for centuries produce drugs) led to an explosion of research into plant- for their medicinal qualities. For example, magnesium cit- based synthetic drugs. Today, this research continues as roots rate, contained within a lemon-fl avored carbonated beverage, and tubers from newly discovered species of plants from the Amazon basin are being tested for possible medicinal use.5 is used as a laxative to relieve constipation and cleanse the bowel before certain medical procedures. The chemical mercury and a large number of mercury- Genetic Engineering based compounds were used to halt the epidemic spread of The future of drug manufacturing may be in genetic engi- the blood-borne disease syphilis. Syphilis is the only disease neering. Genes are the architects of cell construction and thought to have been transmitted from the New World to the contain the blueprint for protein production—the proteins Old World.5 that regulate cell function. Some diseases (e.g., hemophilia 616 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. and cystic fi brosis) are thought to be caused by a failure of chemists are able to group drugs into classifi cations accord- a gene to produce a certain protein. Genetically engineered ing to their common chemical makeups and thus understand medicine involves inserting a therapeutic gene into the mal- the specifi c chemical nature of a drug. functioning cell via a benign viral vector and allowing

the After further development, manufacturers will assign a cell to produce the correct protein again. This process could simpler to pronounce generic name to the drug. The generic eradicate the disease. name is often the drug name listed by the manufacturer in the This approach to treating disease is still experimental United States Pharmacopeia (USP). The U.S. Pharmacopeia but holds a great deal of promise. Pharmacogenomics, a is a listing of all of the drugs legally manufactured or for sale combination of pharmaceutical research with the study of in the United States. The letters USP follow the generic name the human genome, promises to fi nd other new ways to treat after it is listed in the U.S. Pharmacopeia. disease. With the human genome map completed in February After suffi cient research has been done and a drug is 2001, scientists have started to look at individual gene varia- approved for distribution by a company, that company often tions, called “single nucleotide polymorphisms” or snipes, will patent the drug to prevent other manufacturers from pro- that cause or lead to disease or adverse drug reactions. ducing the same drug. To distinguish a patented drug, manu- For example, a liver enzyme called CYP2C6 eliminates facturers will assign a unique third name, called the trade at least 30 different drugs from the body including beta- name. blockers, tricyclic antidepressants, antidysrhythmics, and opiate derivatives. By affecting this liver enzyme, it is pos- Drug Classifi cation sible to give smaller but still effective doses of medicine. The effi ciency of drugs in the future may be vastly improved if Drugs are divided into two classifi cations: prescription and scientists can make cells produce enzymes which assist the nonprescription. Drugs that cannot be dispensed by a phar- transportation of drugs into the cell.7 macist without the written or verbal order of a physician or a Currently, some drugs are genetically engineered pro- mid-level healthcare provider, such as a physician’s assistant, teins that replace missing proteins in the body. For example, are called prescription drugs. The amount, or dose, of drug Humulin™ is a genetically engineered form of human insulin. in a prescription drug can have serious side effects. Therefore, their administration requires careful patient monitoring by a Drug Terminology healthcare provider. By defi nition, a drug is any material which, when injected, ingested, inhaled, or absorbed into the body, is used for the diagnosis, treatment, or cure of a disease or condition. Some Street Smart drugs may have more than one purpose. For example, the drug naloxone is often given to patients who are unconscious All prescription medications are federally mandated for an unknown reason but who are suspected of having over- dosed on opiates. Naloxone reverses the physiologic effects of to display the legend “Caution: Federal law prohibits the opiate. If the unconscious patient does not respond to the dispensing without prescription” and therefore are naloxone, then an opiate overdose is less likely to be the cause called legend drugs. of unconsciousness. In this situation, naloxone is used as both a diagnostic drug and a treatment for opiate overdose. Every drug is assigned three names, each with a specifi c Although Paramedics are seldom asked to read a pre- meaning to a different group of people (Figure 29-1). As scription from a physician, the pharmacist often directly chemists and pharmacists develop new drugs they normally transcribes the physician’s written prescription onto the assign each a chemical name. A chemical name is a descrip- prescription label. Paramedics frequently read, review, and tion of the drug according to its elemental chemical makeup document what is on a patient’s prescription label. Therefore, and molecular structure. By utilizing a chemical name, Paramedics should understand abbreviations that are rou- tinely found on prescription labels (Table 29-2). There is an increasing practice of using plain English in a prescription, especially because of electronic prescriptions. As the name implies, nonprescription medications can be purchased by the public without a prescription. Nonprescription drugs are generally sold by pharmacists over-the-counter (OTC) so patients can self-treat minor i llnesses. The Health Care Financing Administration (HCFA) estimates that 6 out of 10 medications purchased in the United States are OTC. Presently, there are over 300,000 OTC Figure 29-1 An example of a drug’s names. medications on the market.5,8 Introduction to Pharmacology 617 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Table 29-2 Common Prescription Notations a before kg, Kilo kilogram PRN, prn whenever necessary ac before meals KVO keep vein open pt pint, patient ad lib as desired L liter qh every hour AM, am morning LA long acting q2h every 2 hours amp ampule Ib pound q3h every 3 hours b_id twice a day mcg microgram q4h every 4 hours C with mEq milliequivalent QNS quantity not suffi cient cap capsule mg milligram qs quantity suffi cient Cl chloride ml, mL milliliter (equivalent to cc) qt quart cm centimeter mm millimeter R rectal DC discontinue Na sodium _RL, R/L Ringer’s lactate DS double strength NaCl sodium chloride S without DW distilled water NEB nebulizer SubQ, subq subcutaneous D5W dextrose, 5% in water NG nasogastric SL sublingual EC enteric coated noc night sol solution elix elixir NPO, npo nothing by mouth SR sustained release ER extended release NS, N/S normal saline (sodium stat immediately and once only Fe iron chloride, 0.9%) supp suppository fl fl uid Ø none tab tablet Gm,g gram OTC over the counter tbsp, T, tbs tablespoon gr grain oz ounce tid three times a day gtt drop p after TO telephone order h, hr hour pc after meals tsp, t teaspoon IM intramuscular PCA patient controlled vag vaginal IV intravenous analgesia Vit vitamin IVPB intravenous piggyback PM, pm afternoon VO verbal order K potassium po, PO by mouth, orally KCL potassium chloride Note: Abbreviations should be written without periods. remain undiagnosed until the illness reaches crisis propor- Street Smart tions. Furthermore, citizens who are attracted to an OTC drug’s purported action, as advertised by means of the popu- lar press or the Internet, may not read the FDA mandated Seasoned Paramedics know that the patient’s warnings on the drug’s label. Complicating matters, it is prescriptions can often lend a great deal of insight into estimated that 20% of the American public are functionally the patient’s past medical history. Patients frequently illiterate and cannot read the label’s warnings.9 As an overall store prescription medications in medicine cabinets in result, OTC drugs can be unsafe or, when improperly used, can cause unexpected side effects. the bathroom, in the bedside stand, or in the kitchen For these reasons, Paramedics should recognize that next to the water glasses. In some cases, patients may OTC medications are potentially dangerous, can have unde- have already listed the prescriptions for emergency sirable interactions with other drugs, and that OTC drugs are a part of the patient’s medical history. The Paramedic should responders and placed the list in a “vial of life.” These consider including a list of the OTC drugs that the patient is vials are often stored in the refrigerator and a “vial taking in the patient care report. of life” sticker placed on the outside of the The difference between prescription and OTC drugs can refrigerator door. sometimes be just the strength of the preparation (i.e., its potency). In smaller doses, the drug may be relatively safe for patient self-administration, whereas at higher doses there is a The public, in an effort to lower healthcare costs, have greater potential for harm to the patient if the OTC drug is mis- increasingly been self-diagnosing, self-prescribing, and self- used. For this reason, the higher dose medication requires a pre- administering OTC medicine. This practice is not without its scription. Ibuprofen is an example. Ibuprofen comes in 200 mg, dangers. Serious symptoms can be masked by OTC medi- 400 mg, and 800 mg strengths. The public can buy the 200 mg cations. Subsequent errors in medical judgment can occur, dose of Ibuprofen over-the-counter, whereas the higher strength resulting in a life-threatening medical condition that may tablets require a physician’s prescription and a pharmacist to 618 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. dispense it. This prescription guarantees a licensed healthcare The United States Pharmacopeia (USP) drug reference is provider has determined the medication is safe for the patient created by an independent nongovernmental science-based pub- to use at that strength and that a licensed healthcare provider is lic health organization called the United States Pharmacopeia. monitoring the patient’s health while taking the drug. The United States Pharmacopeia is made up of over 1,000 sci- entists, practitioners, and representatives from various colleges Herbal Remedies of medicine and pharmacy who set the standards for medica- tion manufacturing in the United States. This group of physi- The medicinal use of herbs, also called botanicals, is also cians, pharmacists, and scientists meets every fi ve years, at increasing across the United States. This increased use of the United States Pharmacopeial Convention, to discuss and herbal remedies may possibly be as a result of disenchant- adopt recommendations presented from the internal Council ment with traditional western medicine on the part of some. of Experts (COE) regarding new drugs to be added to the However, the use of botanicals can create new problems for United States Pharmacopeia listing. The National Formulary the patient and the Paramedic. Many patients who are taking (NF), another drug reference, is a manual that lists medica- herbal remedies are confounding their medical treatment with tions which are approved for prescription. It contains specifi c the addition of untested herbal preparations which can cause chemical information that is more helpful to the pharmacist and unpredictable consequences. Therefore, Paramedics should manufacturer than the physician. Today, the U.S. Pharmacopeia know the effects of some of the more common botanicals and (USP)—as well as the National Formulary (NF), which is part their potential interaction with the drugs that the Paramedic of the USP—is recognized by the Federal Drug Administration would be administering (Table 29-3). It is important that the and contains the standards of purity, dose, formula, and other Paramedic list all herbal products along with over-the-counter information for drugs. The USP is, per the Federal Food, Drug, and prescription medicines on the patient care report. and Cosmetic Act (2 U.S.C.321), the authority for drug manu- Observant Paramedics may note the presence of teapots, facturing in the United States. The USP is a two-volume text. pots and pans, and the like and ask the patient questions about The fi rst volume includes all prescription medications and the herbal remedies. Methods of botanical administration include second volume includes all over-the-counter medications. potable infusions (boiling water over the top of the herbs and Another reputable source of information about prescrip- immediately drawing off the solution), decoction (bringing tion and over-the-counter medications is the Physician’s water to a boil then steeping the herbs like one would a tea- Desk Reference (PDR). The PDR is a compendium of manu- bag and drinking the resulting solution) and cold maceration facturer drug-prescribing information which is usually found (letting herbs steep in cold water). in a package insert required by law to accompany all medica- tions. These Food and Drug Administration (FDA)-mandated Sources of Drug Information inserts contain information, including common side effects, obtained during drug testing trials. A pharmacopeia is a list of the drugs commonly used in a It is sometimes diffi cult for a Paramedic to obtain infor- country. The fi rst U.S. Pharmacopeia was published in 1820 mation quickly and in useful form from the USP, the NF,

or as a guide to apothecaries who collected plants and fl owers the PDR. Quick reference books, such as Delmar’s Drug and for physicians who compounded their own remedies.10 Reference for the EMS Provider by Richard Beck, are fast and Typically, a group of physicians, pharmacists, and other pro- convenient ways to obtain that information in a user-friendly fessionals, create a pharmacopeia. manner. These references typically group medications Table 29-3 Partial List of Common Botanicals Name Use Side Effect/Precaution Aloe vera Heal wounds; Laxative Potassium loss Cascara sagrada bark Laxative Intestinal obstruction; Potassium loss Chamomile Anti-infl ammatory Anaphylaxis; Cross allergy—Ragweed Cranberry Urinary deodorizer Diarrhea Echinacea Infections Cross allergy—Sunfl ower seeds Garlic Lower blood pressure Reduces platelet aggregation; Interacts with blood thinners Reduces platelet aggregation; Affects calcium channel blockers Ginger Morning sickness (pregnancy-induced hypertension) Ginkgo biloba Depression; Alzheimer ’s disease Reduces platelet aggregation; Cross allergy—Poison ivy Ginseng root Improve concentration Interferes with digoxin; Hypoglycemia Kava kava Sedative Worsens Parkinson symptoms Licorice Upper respiratory infection Use with thiazides—increased potassium loss St. John’s wort Herpes simplex; Depression Hypertensive crisis—if taken with tyramine-containing foods Introduction to Pharmacology 619 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. together in classifi cation by body system or by clinical indi- Historical Legal Developments cation. These reference manuals provide further information on a drug’s action, dose, use, risk during pregnancy, common in Pharmacology side effects, and treatment of overdose. Every Paramedic The image of a medicine man in a top hat leaning over the should have a drug reference available to identify unfamil- side of a painted wagon, extolling the virtues of a snake oil iar patient medications. Knowledge of a patient’s medication remedy, is all part of the lore of the American West. It is also history can lend insight into the patient’s condition. Many the genesis of many modern drug laws. These medicine men, Paramedics also create their own drug cards, handy pocket as well as catalog mail order houses and self-anointed doc- references that contain a partial listing of pertinent informa- tors, sold a variety of concoctions which promised to cure tion (Figure 29-2). everything from arthritis to the common cold. Many of these cures did not work and, worse yet, many of them contained dangerous drugs such as opium and chloral hydrate.11 MANNITOL In an effort to protect the public from false advertising Osmitrol and adulterated medicine, Congress enacted the Pure Food and Drug Act of 1906. The law prohibited the use of false CLASSIFICATIONS or misleading claims. The law further stipulated that if a Pharmacologic: Osmotic diuretic medicine contained any of the 11 “dangerous” drugs, then Therapeutic: Diuretic the drug(s) had to be listed on the label. Additionally, the Pure Food and Drug Act of 1906 recognized the National MECHANISM OF ACTION: Mannitol increases osmotic pressure in Formulary and the United States Pharmacopeia (USP) as the the glomerular fi ltrate. This inhibits the reabsorption of water offi cial drug standards for the United States. and electrolytes, which causes their excretion in the urine. Unfortunately, there were many loopholes in the law. For THERAPEUTIC BENEFIT: The diuretic action of mannitol causes a example, the federal law did not apply to drugs produced in a dehydrating effect on the brain. state and then sold only within that state. The addition of the INDICATION FOR PREHOSPITAL USE: Mannitol is used to relieve Durham-Humphrey amendment in 1952, which included new excessive intracranial pressure. regulations regarding labeling and the refi ll of prescription CONTRAINDICATIONS: ■ Do not administer mannitol to patients medications, closed some of these loopholes. The amend- with: ■ Hypersensitivity to the drug. ■ Preexisting dehydration. ment also required the addition of a written warning, called ■ Active intracranial bleeding. a legend, for drugs that are injected, that are investigational, PRECAUTIONS: Use caution in administering mannitol to patients or that are potentially habit-forming (Figure 29-3). Perhaps who show a tendency to congestive heart failure, because mannitol more importantly, the amendment described a new class of may cause a sudden expansion of extracellular fl uid, which could bring on congestive heart failure. drugs for which a prescription was not required, the over-the- counter (OTC) drugs. ROUTE AND DOSAGE Adult: 1.5–2 g/kg of a 20% solution by IV infusion, using an in-line IV Controlled Substances Legislation fi lter. Mannitol comes in a 5, 10, 15, or 20% 500-mL solution. Pediatric: Not recommended for prehospital use. The use of opium, with its long and undistinguished history as a drug of abuse, ultimately led to many of the modern narcotic ADVERSE REACTIONS AND SIDE EFFECTS drug laws. Opium, a product obtained from the poppy plant • CNS: Headache, confusion. (Papaver somniferum), was freely available over the counter • Cardiovascular: Tachycardia, chest pain, congestive heart failure, pulmonary edema. • Eyes: Blurred vision. • Fluids and electrolytes: Dehydration. • Gastrointestinal: Nausea, vomiting, thirst. PARAMEDIC IMPLICATIONS: ■ Monitor the patients closely for any signs of dehydration, which include: ■ Fever. ■ Thirst. ■ Decreased skin turgor. ■ Dry skin and mucous membranes. ■ Mannitol has a tendency to crystalize at temperatures below 45°F. Use an in-line fi ler when administering mannitol to fi lter any crystals out of the solution. DRUG INTERACTIONS: ■ Additive CNS depression can result if mannitol is administered with other CNS depressants. ■ Mannitol can also cause additive adrenergic effects and anticholinergic effects when used with CNS depressants. Figure 29-2 An example of a drug card. Figure 29-3 An example of a prescription legend. 620 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. in the 1700s. Mothers used tincture of opium to control diar- made up of mainly out-of-work prohibition offi cers, was rhea, brought on by cholera or dysentery, because opium has formed to enforce the Harrison Act. Newly deputized federal a powerful constipating effect. Unfortunately, these early narcotic agents immediately arrested some 3,000 doctors for opium preparations, including laudanum and paregoric, were illegally prescribing opiates to addicts. The Federal Bureau very crude and the effects often unpredictable. Occasionally, of Narcotics was later reorganized and became the Drug these drugs would harm the patient as a result. Enforcement Administration (DEA) in 1973.5 In 1820, a German pharmacist, Friedrich Serturner, In furtherance of the intent of the Harrison Act, and attempted to refi ne opium into its active ingredient, ridding as a part of his “war on drugs” campaign, President Nixon it of its impurities. He named the resulting drug “morphia,” signed the Comprehensive Drug Abuse Prevention and after the Greek god Morpheus, the god of dreams.12 The com- Control Act of 1970 (Controlled Substance Act) into law. bination of the increased availability of morphine and the This expanded the authority of the DEA. Contained within invention of the hypodermic needle in 1850 led to the wide- the Controlled Substance Act were schedules of potentially spread use of morphine as an pain reliever (analgesic). dangerous and addictive drugs which had special restrictions In a continuing effort to improve on opium, other deriv- (Table 29-4). atives of opium were also produced. In 1898, the German pharmaceutical company Bayer produced the semi-synthetic opium derivative diacetylmorphine and branded it “hero-in,” Street Smart the hero drug which had the same ability to relieve pain as morphine but was safer. Unfortunately, heroin did not live up It is important to remember that the federal schedule to its promise and the medical community largely abandoned its use in favor of morphine. of narcotics includes non-opiate substances, such as Opium and morphine use in the United States reached its marijuana and cocaine. The term “narcotic” should not pinnacle in the late 1800s and opium was readily available to be used interchangeably with opiates. The Paramedic the public. As opium dens and pharmacies started to dispense should specifi cally refer to opiates by name. larger and larger amounts of opiates, correspondingly larger numbers of people were becoming addicted to opium. In response to the growing drug problem, the United States Congress passed the Harrison Act of 1914.13 The Drug Misuse versus Drug Abuse Harrison Act made it illegal to obtain “narcotics” (e.g., mor- The difference between drug misuse and drug abuse is an phine) without a prescription. The list of narcotics included important distinction. Drug misuse implies that the drug is drugs such as cocaine, which is a stimulant. (Marijuana would not being used as prescribed and can lead to problems of later be added to the list.) toxicity. Drug abuse implies concerns about dependency and However, the problem of opiate addiction was largely intentional improper use of a drug. Drug misuse is a complex unaffected by the Harrison Act because physicians continued issue which includes unintended drug interactions as a result to prescribe the opiates. In a challenge to the Harrison Act, the of polypharmacology (multiple drug actions). Supreme Court ruled that the act of supplying addicts, even Drug abuse involves the intentional misuse of drugs, pre- when the narcotics were obtained under physician’s prescrip- scription as well as illicit, for a purpose other than the diagno- tion, was illegal. In 1930, the Federal Bureau of Narcotics, sis, treatment, or cure of a disease or condition. Drug abuse Table 29-4 Schedule of Drugs and Examples of Controlled Substances Class Defi nition Examples Restrictions I High abuse, No medical use Opium, Marijuana, LSD Special protocol II High abuse, Limited use, Severe Fentanyl, Codeine Triple prescription, No refi ll, See Note dependence III Lower abuse, Medical use, Small amounts of codeine Limit six months, No more than fi ve refi lls, See Note Moderate dependence combined with aspirin or acetaminophen paregoric IV Minor abuse, Medical use, Minor Barbiturates, Benzodiazepines Limit six months, No more than fi ve refi lls, See Note dependence V Low abuse Medical use Limited Cold remedy May require prescription physical or psychological dependence Note: Federal law prohibits the transfer of this drug to any person other than the patient to whom it was prescribed. Source: DEA pharmacist’s manual—an informational outline of the Controlled Substance Act of 1970. U.S. Department of Justice, Washington D.C. Red Book, 1996. Introduction to Pharmacology 621 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. often leads to dependency, a craving for the drug that can lead FDA immediately established a drug approval process that to socially unacceptable behaviors and/or the person’s inabil- refl ected these regulations. ity to perform activities of daily living (ADL). Now, when a pharmaceutical company manufactures a Dependence on a drug occurs when a person has a com- new drug, or has an old drug that is being used for a new pur- pulsive desire to have a drug, and the drug becomes the sole pose or at a new strength, it has to apply to the FDA to make source of satisfaction for that person. Dependence also can be the drug an “investigational new drug” (IND). Before a drug physical, a biochemical change in the body as a result of taking can be IND certifi ed, the manufacturer is required to submit the drug, or it can be psychological, the compulsive desire to animal studies to the FDA that identify the drug’s therapeutic have the drug. Habituation is the mildest form of psychologi- dosage, its lethal toxicity, its therapeutic range, and its thera- cal dependence. Cigarette

smokers, dependent upon the stim- peutic index. ulant effects of the nicotine in the cigarette, have a “smoking The therapeutic range of a drug starts at the minimally habit.” In some cases, the habit can be stopped without any effective dose (the dose that elicits the desired therapeutic harm to the individual. Psychological dependence becomes response) and concludes with a maximum dose (the dose pathological when the person insists that the drug is needed after which any more drug does not produce any more of the in order to survive, despite scientifi c evidence to the contrary, desired therapeutic effect). Somewhere between the maxi- and takes antisocial action in order to obtain it.14 mum and minimum dosage, within the therapeutic range, is the therapeutic dose (the amount of drug that effectively Physical Dependence creates the therapeutic effect in a majority of patients). The therapeutic dose can also be thought of as the median effec- Physical dependence is more than severe psychological tive dose, the ED50. dependence. Physical dependence occurs when the body At the other extreme is the lethal dose of the drug, or LD50. adapts, biochemically speaking, to the constant presence The LD50 is shorthand for lethal dose 50%, where 50% of the of the drug and integrates the drug into the body’s metabo- test animals given a certain dose of medicine died. LD50 is the lism. In short, the body needs the drug in order to maintain median lethal dose. It should be recognized that patients can homeostasis. The following example is illustrative of physi- still succumb to doses far less than the LD50 and caution should cal dependence. always be practiced whenever giving a drug. Manufacturers Coffee drinkers enjoy coffee because it contains the also have to describe the modes of absorption, distribution, stimulant caffeine. Caffeine interferes with adenosine recep- metabolism, and excretion of the drug (i.e., its pharmacokinet- tors by means of a competitive blockade. Adenosine, a neu- ics) before the FDA can approve the drug as an IND. romodulator in the peripheral and central nervous systems, A drug’s therapeutic index is the ratio of the differ- normally attaches to adenosine receptors and reduces cyclic ence between the median effective dose (the ED50) and the AMP levels. Cyclic AMP is important to neurotransmission. median lethal dose (the LD50) of a drug. Drugs with less After a time, the body adapts to the high caffeine levels and than a two-fold difference between the ED50 and the LD50 greater amounts of caffeine are needed to produce the same are defi ned as having a narrow therapeutic index, as defi ned effect. Subsequently, when a coffee drinker suddenly stops in the FDA regulations (320.33(c)CFR 21). A drug with a drinking coffee he can experience irritability, headache, and narrow therapeutic index has a greater chance of causing tox- weakness as a result of the unbalancing of the nervous sys- icity in a patient (Table 29-5). Therapeutic index represents a tem. These withdrawal symptoms indicate a physical depen- calculated safety margin used when prescribing a drug. The dence upon the drug. prescribing healthcare provider has to carefully monitor the patient for toxicity. New Drug Development After the death of over 100 people in 1937, following an Table 29-5 Drugs with a Narrow ingestion of a new drug called “elixir of sulfanilamide,” Therapeutic Index Congress enacted the Food, Drug, and Cosmetic Act, which • Aminophylline prohibited the sale of new drugs before thorough safety test- • Digoxin ing. While the federal government had previously required • Isoproterenol that a drug be properly labeled and safe to use, there was no guarantee that the drug was even effective against the condi- • Lithium tion for which it was prescribed. • Phenytoin The passage of the Kefauver-Harris Act in 1962 went • Procainamide beyond the Food, Drug, and Cosmetic Act of 1937 by adding • Quinidine a new condition to the sale of drugs within the United States. • Valproate The law required that all drugs undergo an extensive review • Valproic acid that not only ensured the public’s safety, but also reassured • Warfarin the public that a drug would do what it claimed to do.15,16 The 622 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. FDA IND Status Drug companies willingly undertake this expense, in part because it lowers their product liability. A manufacturer can Once designated as an IND, further studies of the drug are be held responsible (liable) if the product is defective (not required. In Phase I, an initial pharmacologic evaluation has to fi t for its suggested use or results in harm to the consumer). be performed on the drug to determine modes of absorption, dis- The FDA process helps to ensure that risks are revealed, that tribution, metabolism, and excretion in normal healthy human the manufacturer knows the effect of the product, and that a volunteers. These trials are intended to prove the safety of the reasonable amount of research was performed to protect the IND in human use, not necessarily the effectiveness of the IND. public. The remaining jeopardy for the manufacturer exists In Phase II, a limited controlled evaluation of the drug during the drug’s processing. Major drug manufacturers have is performed upon target populations who have the disease vigorous quality assurance programs to ensure that the drug is for which the drug was developed. Modes of absorption, dis- pure throughout the manufacturing process, from production tribution, metabolism, and excretion then are established for to packaging. this special population of patients. Assuming no diffi culties, the IND would next undergo the Patented Drugs fi nal phase, or phase III, an extended clinical evaluation among the target population under selected conditions. Study “proto- New drugs are typically patented, ensuring the manufacturer cols” would be published and then a determination of clinical exclusive dominion over the drug for a specifi ed period of effectiveness would be established. Issues such as drug dosage time. This allows for a profi t to be made as the manufacturer range and patient drug tolerance are clarifi ed. During phase markets the new drug against older drugs. However, patents III, common side effects are usually described and ranked are time-limited. In many cases, another drug manufacturer according to prevalence in the study’s participants. After the is waiting to produce the same (or a similar) drug, with- thalidomide tragedy of the late 1950s, special attention has out the expense of research and development, in hopes of been given to the effects and potential risks to an unborn fetus. making a profi t. To extend the patent, some pharmaceutical The FDA establishes a drug’s safety for a pregnant woman and companies will expand the drug’s use to include children, a places the drug into one of fi ve categories (Table 29-6). new use of an existing drug. Eventually, however, the patent After completion of the IND process, the FDA either permits expires on all drugs and the drug profi tability declines. This the drug to be marketed and places it in a “new drug” category or fact of business is factored into the decision to develop a returns the drug for further testing (a “one, two, three, and out” new drug. approach). If a drug is designated a new drug, then the pharma- ceutical companies monitor for post-marketing drug interactions Off-Label Use and adverse reactions as part of ongoing surveillance. In some cases, a physician may elect to use a drug for It can take over 12 to 15 years for each new drug to other than its FDA-approved use. While there is some complete the FDA process and may cost as much as $500 risk involved for the physician in prescribing a drug to be million in research.17 Only one in 5,000 potential drug com- used for other than its FDA-approved use, such an action pounds makes it through the process. Seven out of ten new is permitted and is considered to be part of the practice of drugs do not make enough profi t to cover the costs of initial medicine. research and subsequent development costs. These factors Off-label use often occurs when a generic drug, which is have led to increased drug costs for the consumer but have no longer protected by patent, is used for a new indication. In also ensured that safer and more effective drugs are being some instances, it is not cost effective for the pharmaceuti- manufactured. cal companies to research the new indication of these older drugs. Fortunately, this does not preclude the physician from prescribing that drug if, in the physician’s professional opin- Table 29-6 Pregnancy Safety Categories ion, the benefi ts outweigh the risks. A Adequate, well-controlled No risk to human fetus studies in pregnant women Orphan Drugs B Animal studies No risk but no studies to Drug therapies for rare or uncommon diseases are generally substantiate human risk nonprofi table. Development and research for drugs designed C Animal studies Adverse risk but no studies to for these special conditions, called orphan drugs, are often substantiate human risk; question underfunded at best. To provide this population of patients of risk/benefi t analysis with viable treatment alternatives, Congress passed the D Adequate, well-controlled Positive human fetal risk; question Orphan Drug Act of 1983. studies or observational of maternal versus fetal life The Orphan Drug Act provides grants to manufacturers studies in pregnant women and research centers to investigate drug therapies for rare dis- X Adequate, well-controlled Known fetal anomalies; risks eases such as Von Willebrand’s disease or Raynaud’s disease studies or observational studies outweigh benefi ts and create these orphan drugs.17 The FDA classifi es these in animals or pregnant women orphan drugs as “V.” Introduction to Pharmacology 623 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Medicine Errors bronchospasm, but a frequent side effect was tachycardia, a problem for patients with a cardiac condition. Continuing Despite all of the precautions that are taken during the pharmaceutical research aimed at reducing or eliminating research, manufacture, distribution, and preparation of drugs, these bothersome side effects resulted in a more refi ned drug. mistakes can occur. In 1993, the FDA launched its drug The next generation of asthma drugs caused less nervous- watchdog program called MedWatch.18,19 MedWatch is a vol- ness, palpitations, and tachycardia. untary program utilized by healthcare professionals to report adverse or unusual drug reactions and errors. MedWatch identifi es those drugs and medical devices that have, or could Pharmacokinetics have, resulted in death or risk of death, hospitalization, dis- ability, or birth defects. The problems are then reported to the A drug’s therapeutic value is infl uenced by several factors drug manufacturers for corrective action. including the speed of onset of the drug’s effect, the inten- Despite this effort, in 1999 the Institute of Medicine—in sity of the drug’s effect, and the duration of the drug’s effect. its report, “To Err Is Human”—reported that there were These factors are largely the result of the drug’s time and ease 44,000 to 98,000 preventable deaths and 500,000 preventable of absorption, its distribution from the plasma into the tissue injuries due to medical errors.20,21 A subset of those medi- of the target organ, and its eventual retention or elimination cal errors is medication error. The Institute of Medicine esti- from the body. Pharmacokinetics is the study of how these mated that over 7,000 deaths occur annually as a result of factors—drug absorption, distribution, detoxifi cation, and medication administration errors. elimination—affect a drug’s therapeutic value. Alarmed by these statistics, and the attendant implications, professional pharmacists began their own program of

medica- Absorption tion administration error reporting through the United States In a sequential fashion, the fi rst phase of a drug’s “life” is Pharmacopeia (USP) called MedMARx.22 While pharmacists absorption. For a systemic drug to be effective, it must get had a program for medication error reporting (MER) since 1991, into the bloodstream and be transported to the target organ. the new program sought to understand medication administra- The drug’s movement from its site of administration into the tion errors, not just medication labeling and packaging errors. plasma in the blood is a function of the route of administra- The MedMARx program of the USP is a self-reporting tion. In the case of drugs given intravenously (IV), the drug is Internet program. The focus of these anonymous and volun- instantly available in the blood plasma. However, most medi- tary reports is problems with the process by which medications cations are not given IV; most are given PO (“per os” or Latin are given rather than medication side effects and reactions. for “by mouth”). In that case, the absorption goes through a During 2000 alone, over 184 medical facilities reported over complicated process which will be discussed shortly. Specifi cs 41,296 medication errors.23 Medication errors were classifi ed of the methods of drug administration are discussed in Chapter as causing harm, no harm, or having a potential for harm. 26. However, it is important to understand the impact of medi- Fortunately, 97% of the errors caused no harm. However, 5% cation administration of the various drug administration tech- of reported medication administration errors did cause harm niques as they relate to drug absorption and distribution. For and affected about 1,200 patients. purposes of this discussion, medication administration can be grossly categorized as either enteral (via the gastrointestinal system) or parenteral (other than the gastrointestinal system). Principles of Pharmacology Well over a half million medications—both prescription and Enteral Drug Administration OTC—are available on the market, each asserting that it is the Enteral administration of medication, via the GI tract, is the most effective medication for a specifi c condition or disease. most common form of medication administration. While The basis of these claims lies in the drug’s intended biological easy to administer, multiple intervening factors make enteral effect. The intended biological effect of a drug, also called its medication absorption less predictable and therefore less therapeutic effect, is to modify a tissue or an organ’s function. desirable during an emergency. Drugs can enhance a bodily function by increasing or replac- To begin, once a PO medication is swallowed, the fi rst ing a chemical in the organ. They can also preclude or prevent impediment to drug absorption is the stomach. While the a chemical from having an effect on the organ by blocking or stomach has a rich network of blood vessels for ready absorp- competing with the body’s own chemicals. However, a drug does tion, stomach acid, with a pH as high as 1.4, can destroy the not add a new function; rather, it affects the organ’s functions. drug before it can be absorbed. The stomach acid will break While a drug may have a desired therapeutic effect, it down most substances, whether food or drugs, into their ele- often has additional unintended effects as well. These unin- mental components and therefore neutralize many medica- tended effects, called side effects, may be so noxious that tions in the process. the person stops taking the medicine. Frequently the goal If the drug is either unaffected by the stomach acid, or is of drug research is to eliminate these unwanted side effects. protected from stomach acid, it passes through the stomach For example, early asthma treatments effectively reversed into the intestines. In some cases, the drug is transferred from 624 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. the lining of the intestine and moves into the plasma by a drugs are immediately affected by the C450 system and the simple process of passive diffusion. The mechanics of pas- majority of the drug is inactivated.24–27 To overcome this loss, sive diffusion assume that there is more of the drug, often healthcare providers must administer 10 to 100 times the in the form of a salt, on the inside of the gut’s membranous dose that would be given intravenously (IV). For example, lining than in the blood stream, establishing a concentration propranolol, a popular antihypertensive, is usually given 1 to gradient across that membrane. Whenever a concentration 3 mg IV, whereas the oral dose is 80 to 100 mg. Lidocaine gradient exists, the higher concentration will diffuse across cannot be given orally because it is completely deactivated by the intestinal wall to an area of lower concentration until a the cytochrome P-450 system. To eliminate the effects of fi rst balance of concentrations (equilibrium) is met (Figure 29-4). pass metabolism, many drugs (such as lidocaine) are admin- In some cases, a drug molecule is too large to pass across istered directly into the systemic circulation. the intestinal wall into the blood via passive diffusion. In those cases, a protein carrier will convey the drug across the Parenteral Drug Administration intestinal wall and into the plasma, a process called active When a drug is injected directly into the bloodstream, with- transport. This form of transport requires energy, in the form out going through the gastrointestinal tract (the enteral of adenosine triphosphate (ATP). route), then that drug has been given via a parenteral route. However, many physical factors—including shock states, Examples of parenteral routes include intramuscular injec- which slow absorption, and decreased surface contact time tion and intravenous injection. There are 10 parenteral routes secondary to diarrhea—can affect the absorption of drugs for drug administration. The need for numerous parenteral from the gut into the blood, making the absorption unpredict- routes underscores the signifi cance of fi rst pass metabolism able (Figure 29-5). upon drugs. Once the drug has crossed over the intestinal wall, it is in the hepatic portal system. The hepatic portal system is a subsystem of the systemic circulation. The blood volume in the entire gut is in the hepatic portal system and drains through the liver before rejoining the systemic circulation. This passage through the portal vein permits the liver to detoxify any foreign substance including drugs. The liver’s actions upon the drugs, called fi rst pass metabolism, can markedly reduce the amount of active drug available for the Medication form target organ when it reaches the systemic circulation. These (liquid vs. solid, coated vs. not-coated) Passive diffusion of Passive diffusion of a water-soluble drug a lipid-soluble drug through an aqueous dissolved in channel or pore. a membrane. Acid environment D Food D D D D D D D D ATP Shock ADP D D D Carrier-mediated Diarrhea Drug active transport of drug Figure 29-5 Factors that infl uence drug Figure 29-4 Drugs diffusing into the cell. absorption in the gut. Introduction to Pharmacology 625 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Of the 10 parenteral routes, intravenous (IV) drug infu- are given until a steady state of drug is reached in the blood. sions are generally preferred during an emergency. This is While the drug level is constantly climbing and then falling, due to the fact that drug levels in the blood are obtained more if the repeat bolus is given before the drug’s half-life (t½), rapidly and drug levels can be maintained at more of a steady then the sum of the levels will always be at or above the thera- state. The steady-state level of drug results from a combina- peutic level (Figure 29-7). tion of two factors. On the one hand is the amount of drug An example may help clarify this concept. Lidocaine being infused and on the other, the speed or rate of the infu- has been used to treat ventricular ectopy, irregular beats of sion. If a Paramedic starts at the zero state (with no drug in the heart. A constant infusion of lidocaine would take the bet- the blood) and constantly runs an infusion in, without being ter part of an hour to attain a therapeutic level. To speed the affected by other infl uences, then the amount of drug in the process, the Paramedic would start with a bolus of lidocaine blood will increase at an arithmetic rate until it reaches a to boost the level of lidocaine to the therapeutic range and steady state (Figure 29-6). then start an infusion, an IV lidocaine drip, to maintain that However, attaining a drug’s steady state is not that easy. level. Because of the relatively short half-life of lidocaine, Once a drug is in the bloodstream a number of factors begin the drug level drops below the therapeutic level before the to act upon it. First, and perhaps most importantly, the liver infusion has assumed dominance. This lapse in drug level is starts to detoxify the drug (a process called biotransforma- called the chemical hiatus. Logically, if the chemical hiatus is tion) as the blood passes through the liver. Thus, while a drug is being infused it is also being continuously eliminated. The drug decline is largely a function of the liver’s health Bolus and capabilities. Even with a healthy liver, there is a limited capacity to neutralize a drug. Eventually the drug infusion can overwhelm the liver’s capabilities to neutralize the drug Theraputic and the level of drug in the bloodstream will climb. These window two factors—infusion rate and drug decline—slow the climb of the drug concentration toward a steady state. Instead of a straight linear rise in drug levels, a curved exponential rise is observed. When the drug levels attain the targeted value, as manifested by observation of the therapeutic effect, then Time Bolus the drug is at the therapeutic level (t). When the decline of given drug in the bloodstream reaches 50%, this is equivalent to the drug’s half-life (t½). Steady Infusion On occasion, it is inconvenient to wait for a therapeutic level to be attained by a slow and constant infusion of drug. In those cases a single fi xed dose, called a bolus, is given to rapidly boost the drug to the therapeutic level. Thereafter, an Theraputic infusion is started to maintain the drug at that t-level. window In some other cases, it is impractical to continuously infuse a drug intravenously. Instead, repeated boluses of drug Time Infusion Linear started Exponential Repeat Boluses Theraputic window Time Time Arrows indicate bolus doses Figure 29-6 Linear and exponential drug Figure 29-7 Effects of bolus, steady infusion, infusion rate. and repeat bolus on serum drug levels. 626 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Blood concentration of drug Blood concentration Alternatively, the capillaries of the brain have tight slit junctions, preventing toxins and chemicals, including drugs, Theraputic from easily passing into the brain. This obstacle is referred to window as the blood-brain barrier. For drugs to enter the brain, the drug must be lipid-soluble (i.e., able to be dissolved in lipids [fat]). Since the capillary wall membranes are partially made of lipids, the drug literally dissolves into the capillary wall, passes through to the opposite wall, and moves

into inter- stitial fl uid in the brain. These drugs are also referred to as lipophilic, meaning attracted to lipids. Time Hiatus The placenta also provides a partial barrier to toxins, such Bolus Bolus as chemicals and drugs, present in the mother’s bloodstream. While certain enzymes within the placental tissue can ren- Figure 29-8 Chemical hiatus and lidocaine der some chemicals inert (e.g., catecholamines such as epi- administration. nephrine), many other drugs are not acted upon or blocked by the placenta and pass easily through the placenta and into the fetus (e.g., narcotics and anesthetics). Paramedics should always keep in mind that drugs which may be at the thera- left untreated, a potentially life-threatening return ventricular peutic blood level (ED50) for the mother may be at the toxic ectopy could occur. To prevent this occurrence, a repeat bolus (LD50) level for the fetus. Also, the placenta offers a less- of one-half the initial dose is given to boost the drug back up to than-perfect barrier for the fetus from these drugs. The rela- a therapeutic level. This practice illustrates all three injection tively nonselective transfer of drugs across the placenta, and techniques: bolus, infusion, and repeat bolus (Figure 29-8). paucity of research regarding placental drug transfer, requires Distribution the Paramedic to be extra vigilant whenever drugs are being given to a pregnant patient. Once the drug is in the bloodstream it is carried to all the body’s tissues and organs. This distribution is affected by sev- eral factors including blood volume, blood fl ow within the Drug Reservoirs tissues, and permeability of the capillary walls. Drugs bind to certain substances in the body and, in doing so, Blood volume can have a dramatic impact on drug distri- form drug reservoirs. A drug reservoir acts as a drug depot, bution. If a patient is hemorrhaging, then the physical amount storing the drug until it is needed. The effect of a drug reser- of blood which can carry the drug is diminished. The body, as voir is to prolong the drug’s action within the body. There are a part of its compensatory mechanisms, redistributes blood to two types of drug reservoirs: plasma protein reservoirs and core organs. However, key organs may not get the medication tissue reservoirs. needed. Even under normal conditions, certain tissues get The plasma proteins of the blood serve as the fi rst drug higher blood fl ow rates than others; for example, the heart, reservoir. The blood contains plasma proteins (e.g., albumin). lungs, liver, and kidneys get more blood than does adipose As a drug enters the bloodstream, it is attracted to the plasma (fat) tissue. The fact that muscle and fat receive less perfusion protein within the blood and forms a union, binding the drug than other organs during a resting state can be used to advan- to the plasma protein. The protein-bound drug is not free to tage. Injection of medication into deep muscles is more likely interact with target organs, and the measurable level of free- to be slowly absorbed into the bloodstream than medications drug in the bloodstream is lower. In effect, the drug is held injected into a vein. in reserve on the plasma protein, in a circulating depository, until needed. Capillary Diffusion There is a limit to the amount of drug that can be bound to Once the drug gets into an organ’s capillary beds, it must pass plasma proteins. Once all available blood proteins are bound through the interstitial fl uid and into the cells directly in order with the drug, then free-drug in the bloodstream becomes for the drug to have its therapeutic effect. Capillary walls have available for tissues. Therefore, not all of the active drug selective permeability to drugs. Slit junctions, physical breaks becomes protein-bound. The difference between protein- in the integrity of the capillary wall, allow the drug to pass b ound and free-unbound drug which is pharmaceutically into the interstitial space. Capillary beds in specifi c organs, active is expressed in terms of a percentage. such as the liver, have large slit junctions. These larger-than- For example, warfarin (a commonly prescribed antico- normal slit junctions facilitate large molecules, including agulant) is 99% protein bound; that means it is 99% bound drugs, to pass easily from the bloodstream into the interstitial to plasma proteins and 1% active drug in the system. For fl uid and then into the hepatic cells. The drug can then be this reason, warfarin stays in the patient’s bloodstream for chemically altered by special enzymes within the hepatic cell long periods of time and the patient need only take the drug into an inert or non-active chemical called a metabolite. occasionally. Introduction to Pharmacology 627 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. The amount of free-drug available from the plasma pro- IV medications, almost all of the drug is usually bioavailable tein reservoir is therefore a function of the amount of blood immediately. proteins in the blood. Albumin and other blood proteins are primarily formed in the liver. The patient who has liver fail- Volume of Distribution ure, secondary to alcoholism, or diseases such as hepatitis After a drug is in the bloodstream (intravascular space), it is unable to produce these blood proteins. Understandably, will enter into the extracellular space, via diffusion and the doses of highly protein-bound drugs, such as propranolol, active transport, where it will come in contact with the target must be adjusted and smaller doses administered. organ’s tissues. Subsequently it will enter the organ’s cells, An impact of aging is the decline in liver function. As where it will have a therapeutic effect upon the cell. While a result, Paramedics tend to administer one half the normal normally the drug should be equally distributed across all dose of highly bound medications, such as lidocaine, to avoid three compartments—the intravascular, the extracellular, and toxicity in this patient population. the intracellular—in drug equilibrium, often this is not the case. Factors that prevent equal distribution of drug across Drug Competition all three compartments include the size of the molecule, There is a limited amount of blood protein available in the protein-binding, and the constitution of the fl uid within the blood plasma at any one time. When two protein-binding compartments. drugs are present, each will compete for the available protein. The last factor, the constitution of the fl uids in the tis- In effect, this increases the level of free-unbound drug for sue, has a major impact on the distribution of drugs (Figure both drugs. For example, both aspirin and warfarin have high 29-9). Some drugs have an affi nity for water. These hydro- protein-binding capabilities. Giving an aspirin, an anticoagu- philic drugs are attracted to the large volume of water that lant, to a patient on warfarin, another anticoagulant, may lead is contained within the extracellular space. Once a drug is to an increased chance of internal bleeding as a result of the in the extracellular space, outside of the central circulation, release of plasma-bound wafarin.28–30 Drug interaction, and it tends to persist longer. It has a longer half-life, because it subsequent increases in blood serum levels of certain drugs is not acted upon by the liver (biotransformation) or kidneys secondary to competition, is a common source of drug toxic- (elimination). ity. A careful medication history from the patient and cross- reference to drug tables will reveal protein-binding capacity Detoxifi cation and potential competition. The body has an incredible capacity to detoxify drugs using the cytochrome P-450 enzyme system. The cytochrome P-450 Tissue Binding system simply transforms a drug—by oxidation, hydrolysis, Some drugs have an attraction to, and will bind with, cer- or reduction—into a water-soluble compound which can be tain tissues. For example, lipid-soluble drugs, the kind that excreted in the urine. This process, called biotransformation, can pass through the blood-brain barrier, are attracted to adi- pose tissue (fat). Diazepam is both highly protein-bound and Total Body Water lipid- soluble. After an initial dose of diazepam is bound to the plasma protein, a percentage of the drug will further accu- Plasma mulate in the adipose tissue. The result is a depot-like effect, with a quantity of drug being stored in the fat for a prolonged period of time. If the patient is given too large a dose, or Interstitial Extracellular Fluid 1/3 repeated doses, then the result may be a persistent drug effect Fluid beyond the desired timeframe. For example, if diazepam is given for sedation, and the patient is obese, then it may take larger doses of the drug to attain a therapeutic level, the clini- cal goal of sedation. However, once the patient is sedated he will tend to remain sedated for a prolonged period of time. Bioavailability Intracellular Once the drug is free within the blood’s plasma it is said to be Fluid Intracellular Fluid 2/3 bioavailable (i.e., capable of creating its therapeutic effect). Bioavailability is the difference between the amount admin- istered and the amount that is bound and unavailable for use. For example, if an aspirin pill with 325 mg of active ingredi- ent is swallowed, and after various factors come into play, only 150 mg is free and unbound in the blood plasma. Thus, less than 50% of the medication is bioavailable. In the case of Figure 29-9 Percentages of volume distribution. 628 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. primarily occurs in the liver, though biotransformation also to arrive at a fi eld diagnosis and then establishing a plan of occurs in the lungs, intestinal lining, and the kidneys. In some treatment are important. instances, pharmacists have taken advantage of this process and administer inert prodrugs that are converted, by the liver, Elimination into their metabolically active form. For example, heroin is a The primary organ for drug excretion is the kidney. The liver’s prodrug that, when acted upon by the liver, metabolizes into cytochrome P-450 system neutralizes toxins, including drugs, morphine. into water-soluble by-products that pass through the kidneys easily. Some drugs, particularly those with a lower molecu- lar weight, pass through the kidney in their active form. This results in a reduced therapeutic level and the need for repeat Street Smart doses of the drug. The majority of drugs and their inactive metabolites are excreted from the kidneys by a process of passive fi ltration. Certain drugs inhibit the cytochrome P-450 enzyme Therefore, free-drugs, those not bound by proteins, and water- system and indirectly increase the levels of circulating soluble drugs are excreted easily, whereas protein-bound and drug. For example, cimetidine hampers the lipid-soluble drugs are not excreted. Filtration, reabsorption, and eventual secretion are also cytochrome P-450 system’s biotransformation of drugs greatly affected by the urine’s acidity. Drugs that are weak like warfarin and phenytoin, to name just two drugs. acids, such as aspirin, are more easily excreted in a slightly alkaline urine. While the kidneys are the primary organ of excretion, sec- ondary organs of excretion do exist. For example, water-soluble drugs (e.g., salts) can be excreted by any exocrine gland, Rates of hepatic metabolism are affected by the health including sweat glands, mammary glands, and saliva glands. of the individual’s liver. Liver cirrhosis (an obstructive dis- Certain drugs, after biotransformation in the liver, are excreted ease), decreased blood fl ow (shock liver), and even old age along with the bile into the intestine. These drug residuals are all conspire to reduce the liver’s ability to metabolize drugs. then passed out along with the feces. Drugs such as anesthet- Outside infl uences can also have an impact on the liver’s

abil- ics and alcohol are highly volatile and literally “off-gas” into ity to biotransform toxins. Dyes, pesticides, CNS depressants, the lungs, where they are exhaled with every breath. and xanthine derivatives, such as those found in coffee, can The sum of all drug excretion—from the kidneys, enhance the cytochrome P-450 system’s effectiveness, and skin, lungs, and liver—is called the total body clearance. the result is reduced drug serum levels. Hypoperfusion (shock) or diseases of the kidneys, liver, and/ Prolonged exposure to certain drugs causes the liver to or lungs can markedly lower total body clearance, resulting in produce new enzymes to deactivate the drugs, resulting in a a potential toxic accumulation of a drug in the body. decreased blood serum level and a condition called tolerance to be created. It takes increasing doses of drug to overcome the liver’s tolerance of a drug and attain a therapeutic level. Pharmacodynamics Understanding how each drug specifi cally works upon a cell, Toxicity its mechanism of action, helps to explain how the cell will Every drug, in the wrong dose, has the potential to be a poi- respond, how the organ is affected, and the total systemic son. Toxicology, the study of poisons, is therefore a subdisci- response. The study of how drugs come to create their thera- pline of pharmacology. While some think of poisons as those peutic effect is called pharmacodynamics. drugs which, when given in a small amount, can cause death, Drugs can have many effects upon a cell. A drug can this narrow-minded thinking precludes the possibility that cause a cell to increase or decrease its production of proteins, an untold number of other factors could potentiate the drug’s enzymes, and hormones or to inhibit a metabolic function. If effect. This more enlightened perspective is helpful for the the drug inhibits the production of a lipoprotein that is essen- Paramedic who has to treat a patient for whom there is very tial to cell wall production, for example, then the cell wall little background information. will be incomplete and the cell will malfunction. This tactic, It is not the intention of this section to discuss toxicology called chemotherapy, is useful for fi ghting infections. If a in depth, but rather to bring to the Paramedic’s attention that drug cannot differentiate between foreign bacteria and nor- unintentional drug overdoses can be treated with the same mal host cells during chemotherapy, then both cells die in approach as a classic overdose. Unintentional drug over- the process. At fi rst this may appear to be a limitation for a doses, and the resultant toxicity, are a common occurrence drug, but even that situation can been used to a therapeutic whose potential can be mitigated by the Paramedic obtaining advantage. The use of these drugs for cancer patients helps a good history, particularly a good drug history. Also, paying to eliminate the more rapidly dividing cancer cells while pre- careful attention to details like age, weight, sex, and so on, serving a suffi cient mass of host cells for survival. Introduction to Pharmacology 629 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. While there are many different mechanisms of action, of drug that it takes to be potent is called the dose. Dosages the mechanism of action for most drugs can be classifi ed as can vary from person to person, each according to his indi- either drug-receptor interaction, drug-enzyme interaction, or vidual metabolism and genetic makeup. non-specifi c drug interaction. Some individuals develop a resistance to a drug. If this happens, increasing doses of the drug are required to obtain Drug-Receptor Interaction the same therapeutic effect, a development called tolerance. Receptor drugs have an affi nity to a receptor, the portion of Drug tolerance may be the result of the patient’s genetic a cell which attracts a certain molecule. If activation of the makeup, which produces a body chemistry that is less affected receptor causes the cell to react in a specifi c manner, it is or unaffected by the drug. Tolerance may also occur because called a cell receptor stimulator or agonist. If a drug occupies of the development of additional cell receptors. the receptor but does not activate the cell or prevents other The interaction between drugs can occasionally lead to natural receptor molecules from attaching to the receptor, and unexpected or extra effects. For example, two drugs given at the cell is therefore unable to biologically respond normally, the same time may create a new and unexpected third effect. then the drug inhibits the cell and is called an antagonist. That third effect is called synergism. Synergism can be desir- The more a drug is like a naturally occurring chemical able. For example, when promethazine is given with meperi- compound within the body, the more likely that the drug will dine, the effi cacy of the combination is better than each drug have an attraction, an affi nity, to the receptor. In some cases when given on its own. Synergism can also be undesirable, (e.g., epinephrine), the affi nity is extremely strong and the such as when phenobarbital and diazepam are given together. drug is said to be extremely potent. The combined sedative effects can result in central nervous Another infl uence on the drug’s potency is its effi cacy. system depression and respiratory arrest. Once a drug has interacted with a receptor, it may or may not When one drug increases the effectiveness of another cause the cell to react completely; in other words, it may or drug, this is called potentiation. If the drug’s effectiveness is may not have realized its full intended therapeutic effect. The improved, then this may be desirable. Unfortunately, the more better a drug’s ability to stimulate the cell to act, the better its common effect is that one drug is more potent than expected, effi cacy is said to be. Often one of the goals of pharmaceuti- which leads to toxicity problems. cal companies is to increase a drug’s effi cacy. Adverse Drug Reaction Drug-Enzyme Interaction Sometimes a drug creates an unwanted or harmful biological Enzymes act as stimulators within the body, forcing certain response. The subsequent negative impact upon the patient’s chemical reactions to occur within the cell. Enzymes work by health is an adverse drug reaction. When patients experi- combining with a molecule, called a substrate, and acting upon ence an adverse drug reaction, then drug administration is the substrate. Enzyme drugs work by simulating the substrate, stopped immediately and efforts are undertaken to mitigate thereby attracting and engaging the enzyme and preventing the the negative effects of the drug. natural enzyme/substrate combination from working on the cell. Factors that affect if a patient will have an adverse drug These drugs are called antimetabolites because they prevent reaction include extremes of age, extremes of weight, patient the enzymes from stimulating the cell’s metabolism. Certain sex, the time of administration, the patient’s physical condi- cancer drugs, such as methotrexate, are antimetabolites. tion, and genetic factors. Careful attention to these factors and Enzyme drugs can also work by inhibiting the action prompt intervention can create a situation in which, instead of an enzyme directly, thereby preventing the enzyme from of an intolerable adverse drug reaction, a milder side effect is working. The result is that the cell continues to either produce experienced and the patient continues to take the medicine. or break down a chemical. Side effects are other unwanted biological responses to a Nonspecifi c Drug Interaction drug, which are not harmful, adverse drug effects. Whether a patient takes a medication is often a function of the patient’s Some drugs act less specifi cally. For example, mineral oil tolerance to these side effects. Common side effects of many physically coats the intestinal walls and blocks absorption drugs include nausea, dizziness, dry mouth, or diarrhea. Some of nutrients as well as drugs. Other nonspecifi c drug inter- side effects are short-lived. Simple interventions, such as divid- actions include antacids, such as sodium bicarbonate, which ing the dose or slowing the infusion, can make the side effect mix with and neutralize stomach acids. Many of these crude tolerable. For example, a common side effect of nitroglycerin, drug preparations are effective because they often work at a a drug given for chest pain, is dizziness and temporary pos- physical level. tural hypotension. Therefore, to prevent this side effect, the patient should always be forewarned about dizziness and cau- Biological Response tioned about standing quickly after using nitroglycerin. Regardless of the mechanism of action, any drug that is capa- Other side effects, usually long-term side effects, ble of producing the desired therapeutic effect, to affect the can sometimes be mitigated by use of other medications. cell’s function, is considered effective or potent. The amount For example, diarrhea is common with antibiotic therapy. 630 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Therefore, the patient might be instructed to take an antidiar- Type I allergic reactions are often the most severe and rheal medication. can occur within minutes of exposure.34, 35 Also called an ana- phylactic reaction, a type I reaction is mediated by the IgE antibody found attached to mast cells and basophils. Drugs Cultural / Regional differences most accountable for type I reactions are the penicillins and other antibiotics that have a similar structure, including the cephalosporins. The relationship of the patient’s weight to drug dose Type II allergic reactions involve the IgG and IgM anti- is becoming more important in North America as the bodies and lead to an autoimmune response. An autoimmune population tends toward obesity. Several factors response is an unfortunate condition where the body literally attacks itself. Methyldopa, a drug used to treat hypertension, come into play when calculating an appropriate dose has been implicated for drug-induced hemolytic anemia, for of medicine for the obese patient, such as a greater example. volume of blood for drug distribution, altered blood Type III allergic reactions are delayed drug reactions that fl ow (hemodynamics), increased adipose tissue for are caused by the IgG antibodies in the blood. Formerly called serum sickness, the patient experiences symptoms between lipid-binding drugs, and alterations in metabolism in one and three weeks after taking the medicine. Certain anti- general. This subpopulation of patients is at great risk biotics, such as sulfonamides and the anticonvulsant phe- for receiving subtherapeutic doses of medication.31−33 nytoin, have been identifi ed as higher risk for type III drug reactions. A type IV allergic reaction is an infl ammatory reaction secondary to T-lymphocytes and macrophages, such as a con- Allergic Reaction tact dermatitis from poison ivy, that may result from cross- Allergic reactions can be the most problematic of the adverse contamination of topical ointments or crèmes.36 drug reactions, with complications ranging from a contact dermatitis to anaphylactic shock and death. Formerly, terms such as “hypersensitivity,” “drug allergy,” and “anaphylaxis” Idiosyncratic Reaction were used to describe this adverse drug reaction. These three When a drug produces an unpredictable reaction that is not different syndromes (hypersensitivity, drug allergy, and ana- allergic in nature or due to overdose and resultant toxicity, it phylaxis) have a similar mechanism. Whenever a foreign is called an idiosyncratic reaction. An idiosyncratic r eaction substance, such as a drug, enters the body, it can potentially can be described as a highly unusual or abnormal reaction, stimulate the immune response and cause the creation of anti- within a small subpopulation of patients, to a drug that the bodies. These antibody generators (antigens) react with anti- rest of the population can normally tolerate. The basis

for bodies within the body to form an antigen/antibody complex. these rare idiosyncratic reactions is most likely based in the The antigen/antibody complex, in turn, causes the release of individual’s genetic makeup. Malignant hyperthermia (e.g., certain substances, such as histamine, which then produce the an increased core body temperature caused by exposure classic symptom pattern of an allergic reaction. Currently, to certain anesthetics) is thought to be a genetically linked allergic reactions are designated as types I, II, III, and IV. idiosyncratic reaction. Introduction to Pharmacology 631 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. An understanding of the basic principles of pharmacology, pharmacokinetics, and pharmacodynamics provides a foundation for the Paramedic when learning new drugs. Key Points: • Paramedics must understand the actions of any • Healthcare providers use the Physician’s Desk medications that are to be administered. Reference (PDR) as a source of drug information in • the clinical setting. Drugs originally came from plant, animal, and mineral sources. Many are now synthetically • The Pure Food and Drug Act of 1906 and later produced or genetically engineered. amendments worked to regulate medicine sold • to the public by establishing drug standards and A drug is any material which, when injected, classifi cations. ingested, inhaled, or absorbed into the body, is used for the diagnosis, treatment, or cure of a • The Harrison Act of 1914 made it illegal to obtain disease or condition. “narcotics” without a prescription. • Every drug is assigned three names: • The Controlled Substance Act expanded drug ■ The chemical name is a description of a drug enforcement and placed special restrictions on according to its elemental chemical makeup potentially dangerous and addictive drugs. and molecular structure. ■ The generic name is the drug name listed by • Misuse is defi ned as a drug not being used as the manufacturer; if offi cially listed in the U.S. prescribed. Pharmacopeia, it is followed by the initials USP. • Drug abuse involves the intentional misuse of drugs, ■ The trade name is a unique one given to a drug whether prescription or illicit. by its manufacturer. • • The ratio of effective dose for 50% of the Prescription drugs require a pharmacist to have a population to lethal dose for 50% of the population written or verbal order from a physician or mid- is defi ned as the therapeutic index. level provider to dispense the medication. • • Physicians may choose to use a drug for something Over-the-counter (OTC) medications are available other than its intended use, called off-label use. to self-treat minor illness. This type of medication does not require a prescription. • A drug can enhance a bodily function by either • increasing or replacing a chemical in an organ or by Herbal preparations are a form of OTC medications. blocking the body’s own chemicals. • The Paramedic should inquire about prescription • Pharmacokinetics is the study of how drug medications as well as any herbal products and OTC absorption, distribution, detoxifi cation, and medications the patient may have taken. elimination impact a drug’s therapeutic value. • Information about drugs that are recognized by the • Enteral drug administration involves the absorption Federal Drug Administration can be found using the of a drug via the GI tract by either passive or active United States Pharmacopeia (USP) and National transport. Formulary (NF) drug references. 632 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. • Parenteral drug administration does not use the GI • Synergism occurs when two drugs, given at the tract. Examples include IM or SQ injections and IV same time, create an unexpected third effect. administration. • The unwanted or harmful biological response to a • Distribution of medication is affected by blood drug that has a negative impact upon the patient’s volume, blood fl ow within the tissues, and health is an adverse drug reaction. permeability of the capillary walls. • An allergic reaction is an adverse drug reaction. • Only lipid-soluble drugs pass the blood-brain barrier. It is caused by the body’s response to a foreign • substance which produces the classic symptom The placenta provides a barrier to some pattern of an allergic reaction. Hypersensitivity, medications. drug allergy, and anaphylaxis are syndromes that • Drugs bind to substances, forming plasma protein each have this common response mechanism and reservoirs and tissue reservoirs. can be designated as types I, II, III, and IV. • Pharmacodynamics examines a drug’s mechanism of • An unpredictable reaction that is not allergic in action. nature and that is not due to overdose and resultant toxicity is called an idiosyncratic reaction. • Receptor drugs have an affi nity for a receptor on a cell. A drug is called an agonist if the receptor is • Biotransformation, which primarily occurs in the activated by the drug, which in turn causes the cell liver, detoxifi es drugs by using enzymes to transform to react in a specifi c manner. An antagonist drug the drug into a water-soluble compound that can be occupies the receptor side but does not activate excreted in the urine. the cell. • Toxicology is considered a subdiscipline of • Medication dosages are based on the amount of drug pharmacology. necessary for potency. • Elimination of drugs is primarily carried out by the • Tolerance is the physical need for additional kidneys. The total body clearance is the sum of all amounts of a drug to accomplish the same effect. drug excretion carried out by the kidneys, skin, lungs, and liver. Review Questions: 1. Name fi ve sources of drugs. 8. What factors impact a drug’s therapeutic value? 2. Differentiate between prescription medications 9. What is fi rst pass metabolism? How does it affect and over-the-counter medications. drug development? 3. Differentiate a drug’s chemical, generic, and 10. How does impaired liver function lead to high trade names and give an example of each. or toxic levels of protein-bound drugs? 4. Name at least three drug references. 11. Differentiate between an agonist and antagonist 5. Explain how drug misuse is different than drug drug-receptor interaction. abuse. 12. What is an adverse drug reaction? 6. Describe the steps in the development of a new 13. Differentiate between the three syndromes of drug. an allergic reaction. 7. What is the intended biological effect of any drug? Introduction to Pharmacology 633 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Case Study Questions: Please refer to the Case Study at the beginning of the • When only a partial volume of a prefi lled chapter and answer the questions below: amount of narcotic is given? 1. Which drug laws affect the Paramedic’s • During documentation? administration of a narcotic analgesic? 3. Which drug effect is illustrated by giving Katie 2. What does the Controlled Substance Act of 1970 a pain medication along with a drug to control require of a Paramedic: nausea? • At shift change? References: 1. Centers for Disease Control and Prevention. Life expectancy 16. Barron BA, Bukantz SC. The evaluation of new drugs. Current data: United States. Available at: http://www.cdc.gov/nchs/ Food and Drug Administration regulations and statistical aspects fastats/lifexpec.htm. Accessed at May 27, 2009. of clinical trials. Arch Intern Med. 1967;119(6):547–556. 2. Goldberg H. Hippocrates: Father of Medicine. New York: 17. Welling, P, ed. Drug Development Process: Increasing Authors Choice Press; 2006. Effi ciency & Cost Effectiveness (Drugs and the Pharmaceutical 3. Hippocrates, Francis Adams, Translator. The Genuine Works of Sciences). Stockholm: Informa Healthcare; 1996. Hippocrates. New York: Kessinger Publishing, LLC; 2007. 18. White GG, Love L. The MedWatch program. J Toxicol Clin 4. Logan, Clendening C. Source Book of Medical History. New Toxicol. 1998;36(6):645–648. York: Hoeber; 1942. 19. Meadows M. MedWatch: managing risks at the FDA. FDA 5. Porter R. Greatest Benefi t to Mankind: A Medical History of Consum. 2003;37(5):10–11. Humanity. London: HarperCollins; 1997. 20. Kaldjian LC, Jones EW, Wu BJ, Forman-Hoffman VL, Levi BH, 6. Berndt L.William Withering. Journal of Interventional Rosenthal GE. Disclosing medical errors to patients: attitudes Cardiology. Netherlands: Springer; 2005. and practices of physicians and trainees. J Gen Intern Med. 7. Asimov I. Human Brain: Its Capacities and Functions. New 2007;22(7):988–996. York: Mentor Book; 1965. 21. Kaldjian LC, Jones EW, Wu BJ, Forman-Hoffman VL, Levi BH, 8. Phillips KA, et al. Potential role of pharmacogenomics Rosenthal GE. Reporting medical errors to improve patient in reducing drug reactions: a systematic review. JAMA. safety: a survey of physicians in teaching hospitals. Arch Intern 2001;286(18):270–279. Med. 2008;168(1):40–46. 9. Rodman M, Smith D. Pharmacology and Drug Therapy in 22. Hicks RW, Becker SC. An overview of intravenous-related Nursing (2nd ed.). Philadelphia: Lippincott; 1979:17. medication administration errors as reported to MEDMARX, 10. United States Pharmacopeial. United States Pharmacopeia: a national medication error-reporting program. J Infus Nurs. National Formulary 2005 (United States Pharmacopeia/National 2006;29(1):20–27. Formulary). Washington, DC. United States Pharmacopeial; 2004. 23. Savage SW, Schneider PJ, Pedersen CA. Utility of an online 11. Salerno E. Pharmacology for Health Professionals. St. Louis, medication-error-reporting system. Am J Health Syst Pharm. MO: Mosby; 1999. 2005;62(21):2265–2270. 12. Somogyi AA, Barratt DT, Coller JK. Pharmacogenetics of 24. Jacquot C. Bioavailability and “fi rst pass” effect of a drug. opioids. Clin Pharmacol Ther. 2007;81(3):429–444. Therapie. 1978;33(6):683–697. 13. Inciardi J, ed. Handbook of Drug Control in the United States. 25. Pond SM, Tozer TN. First-pass elimination. Basic concepts and New York: Greenwood Press; 1990. clinical consequences. Clin Pharmacokinet. 1984;9(1):1–25. 14. Forrest G. Chemical Dependency and Antisocial Personality 26. Lalka D, Griffi th RK, Cronenberger CL. The hepatic fi rst- Disorder: Psychotherapy and Assessment Strategies. New York: pass metabolism of problematic drugs. J Clin Pharmacol. Haworth Press; 1994. 1993;33(7):657–669. 15. Krantz JC, Jr. New drugs and the Kefauver-Harris amendment. 27. Kwan KC. Oral bioavailability and fi rst-pass effects. Drug Metab J New Drugs. 1966;6(2):77–79. Dispos. 1997;25(12):1329–1336. 634 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. 28. Andreotti F, Testa L, Biondi-Zoccai GG, Crea F. Aspirin 32. Lee JB, Winstead PS, Cook AM. Pharmacokinetic alterations in plus warfarin compared to aspirin alone after acute coronary obesity. Orthopedics. 2006;29(11):984–988. syndromes: an updated and comprehensive meta-analysis of 33. Erstad BL. Dosing of medications in morbidly obese patients 25,307 patients. Eur Heart J. 2006;27(5):519–526. in the intensive care unit setting. Intensive Care Med. 29. Larson RJ, Fisher ES. Should aspirin be continued in patients 2004;30(1):18–32. started on warfarin? J Gen Intern Med. 2004;19(8):879–886. 34. Untersmayr E, Jensen-Jarolim E. Mechanisms of type I food 30. Jeddy AS, Gleason BL. Aspirin and warfarin versus aspirin allergy. Pharmacol Ther. 2006;112(3):787–798. monotherapy after myocardial infarction. Ann Pharmacother. 35. Romano A, Demoly P. Recent advances in the diagnosis of drug 2003;37(10):1502–1505. allergy. Curr Opin Allergy Clin Immunol. 2007;7(4):299–303. 31. Nieman CT, Manacci CF, Super DM, Mancuso C, Fallon WF, Jr. 36. Brunton L, Lazo J, Parker K. Goodman & Gilman’s the Use of the Broselow tape may result

in the underresuscitation of Pharmacological Basis of Therapeutics. New York: McGraw-Hill children. Acad Emerg Med. 2006;13(10):1011–1019. Professional; 2005. Introduction to Pharmacology 635 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. KEY CONCEPTS: Upon completion of this chapter, it is expected that the reader will understand these following concepts: • Maintenance of cardiac rate, rhythm, and pumping ability as support for the brain • Autonomic nervous system control • Mechanisms of action of drugs affecting the heart, lungs, and kidneys Case Study: Mrs. Fein called 9-1-1 because she felt faint and very fatigued. One Paramedic interviewed Mrs. Fein while her partner scanned the medication bottles. “Do you take all of these medications?” one Paramedic asked. Mrs. Fein answered, “Oh yes. I always do what my doctors tell me to do. I am so glad that I have so many fi ne doctors to take care of me.” There were multiple antihypertensives, antidysrhythmics, and diuretics. At least four different pharmacies had fi lled the prescriptions. “I see that you go to several pharmacies to have your prescriptions fi lled,” said the Paramedic. Mrs. Fein replied, “Well, each of my daughters likes a different pharmacy and they often pick up my prescriptions for me.” 636 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Pharmacological Interventions for Cardiopulmonary Emergencies 637 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. OVERVIEW The brain, as the source of one’s being and the seat of one’s consciousness, is the most important organ in the body. Perhaps the two most important support systems for the brain in the body are the heart and lungs. These two organs, through constant adjustment and readjustment, ensure that the brain gets suffi cient oxygen and perfusion of glucose-rich blood in order to function. Any disequilibrium between the heart and lungs results in cerebral hypoxia, hypoglycemia, or hypoperfusion. Persistent hypoxia, hypoglycemia, or hypoperfusion can lead to an alteration in mental status, loss of consciousness, and eventually death. Paramedics are frequently called to treat a patient with loss of consciousness, shortness of breath, or cardiac-related problems. The importance of these two interconnected organ systems to the patient’s health cannot be understated. Paramedics must have an intimate understanding of the heart and lung systems and the treatments which they can provide to support them. The Nervous System two-lane highway, information fl ows to and from the brain along the peripheral nervous system. The afferent division is The brain controls these two vital organ systems through the portion of the peripheral nervous system that is stimu- the autonomic nervous system. Therefore, cardiopulmonary lated by the environment (e.g., by heat or by touch) and sends pharmacology is focused on affecting the autonomic nervous a signal to the central nervous system. The central nervous system. To understand the effects of cardiopulmonary phar- system, in turn, interprets the data and sends a signal via macology, the Paramedic must have an expansive knowledge efferent nerve fi bers to the body to react. In some cases, the of the autonomic nervous system. act is voluntary (e.g., to pat a dog’s head). In other cases, the In about 200 A.D., Galen, the father of medicine, identi- act is involuntary (e.g., a quicker heartbeat when faced with fi ed something “non-tendon” in the muscle. He had identi- the threat of a menacing bear). This involuntary control is a fi ed a nerve.1 Later, anatomists would note that stimulation function of the autonomic nervous system. of these nerves caused muscle movement and they sought to discover what other functions nerves provided. Autonomic Nervous System In the mid-1900s, Dr. William Cullen advanced the idea The autonomic nervous system can be thought of as the that the nervous system was responsible for maintaining the body’s autopilot.3 Essential, life-preserving functions, such physiological balance of all organs within the body. He was as digestion, are maintained by the autonomic nervous sys- correct. The nervous system is responsible for the regulation tem. The autonomic nervous system is further divided into of body functions. Through an intricate system of wire-like two divisions: the sympathetic division and the parasympa- fi bers, called neurons, which are present throughout the body, thetic division. These two divisions of the autonomic nervous messages are sent which stimulate the cells within the organs system compete, to some degree, with one another in order to to respond. maintain equilibrium while adjusting to external and internal The Central Nervous System stress. The sympathetic division of the autonomic nervous sys- The central nervous system, which consists of the brain and tem, whose nerve fi bers originate in the thoracic or lumbar the spinal cord, is analogous to the command and control area of the spinal cord, serves to accelerate the body’s organs. center of an army. Information, or intelligence, from the out- Referred to as the “fi ght or fl ight” response, the sympathetic side world fl ows through the spinal cord to the brain to be nervous system increases heart rate, dilates the bronchioles processed. In many instances, the brain sends a command (a to allow more air movement, and constricts blood vessels, signal) to the organs to respond in a certain manner, via the causing the shunting of blood to the vital core organs.4–7 peripheral nervous system. Because of its “crisis” orientation, the sympathetic nervous system tends to create an “all or nothing” response, meaning The Peripheral Nervous System it simultaneously stimulates all of its target organs. The peripheral nervous system consists of the 12 cranial The parasympathetic division of the autonomic nervous nerves and the 31 spinal nerves that extend from the brain system, whose nerve fi bers originate and extend from the cer- and spinal cord to the organs of the body.2 Similar to a vical or sacral area of the spinal cord, is responsible for the 638 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. more vegetative functions. Referred to as the “feed or breed” perception, and mood. Its impact on mood is an important portion of the nervous system, the parasympathetic nervous feature which many anti-depressant medications depend on system increases gastric motility as well as stimulates erec- for their effectiveness (see MAO inhibitors and selective sero- tions in men. tonin re-uptake inhibitors). The vagus nerve (from the Latin word meaning “wan- dering”) is the major parasympathetic nerve. The vagus Neurotransmission nerve originates in the medulla, exits the skull at the base of the brain, travels down the neck (proximal to the larynx), The process of neurotransmission is a cycle (Figure 30-1). branches into the heart and lungs, innervates the stomach, Understanding this is the key to understanding the drugs which passes through the digestive tract, and ends in the anus. can affect the autonomic nervous system. The phases in the Most organs have dual innervations, both sympathetic cycle are preparation for action, feedback, and preparation for and parasympathetic. However, the parasympathetic nervous another action. The speed or strength of a cycle can be increased system usually dominates. For example, the upper portion of or decreased by a drug’s infl uence during that cycle. the heart, the atrium, has both sympathetic and parasympa- To review, the nerve ending makes and stores neurotrans- thetic nerve fi bers. Yet the parasympathetic nerve, the vagus mitter in pockets called “vesicles” in the terminal end of the nerve, dominates, creating a “vagal tone.” neuron. With stimulation, the neurotransmitter is released Certain select organs only have sympathetic innervation. into the space between the nerve and the target cell, called the For example, the adrenal medulla (which excretes the hormone synapse. In the synapse, the neurotransmitter fl oats over to adrenaline), the kidney, and the lower portion of the heart (ven- the cell and attaches to a receptor. Once the cell is stimulated tricles) are innervated by sympathetic nerve fi bers only. to act, the neurotransmitter is released. It is either reabsorbed by the nerve, called re-uptake, after which it is stored in a Neurotransmitters vesicle; or it is broken down by enzymes and excreted. If the The autonomic nervous system transmits its signal to the process of enzymatic degradation or re-uptake and absorp- target organ (the effector organ), causing the organ to act in tion did not occur, the cell receptors would be continuously response to the signal. The transmission of the signal from stimulated (hyperexcited) or exhausted (desensitized). the nerve to the organ is by means of a messenger called a The effects of drugs on the autonomic nervous system neurotransmitter. There are many neurotransmitters in the can be one of two impacts. The drug either increases the central nervous system. neurotransmitter’s ability to stimulate the cell’s receptors The chief neurotransmitter for the sympathetic nervous (agonist effect) or it blocks the cell’s ability to be stimulated system is norepinephrine, which is chemically similar to (antagonist effect). the hormone adrenaline. Because of its utilization of an adrenaline-like chemical, these nerves are also called adren- ergic nerves. Tyrosine The chief neurotransmitter for the parasympathetic ner- 1. Synthesis of vous system is acetylcholine. Because of its use of acetylcho- norepi- DOPA 6. Re-uptake nephrine line, these nerves are also called cholinergic nerves. These terms—“adrenergic” and “cholinergic”—are important to understanding some descriptions of drug effects. Dopamine For each neurotransmitter, there is a corresponding neu- 2. Uptake into storage roreceptor that receives the neurotransmitter, chemically Dopamine– vesicles connecting with it in a key and lock-like fashion. The linkage of neurotransmitter to cell receptor can cause a cell to change the conductivity of an ion channel in the cell wall, thus mak- Synaptic 3. Release of ing it more or less responsive to a stimulus. vesicle + neurotrans- For example, norepinephrine can cause the cell to open mitter Presynaptic its potassium channels, which in turn causes a cascade of receptor events, called depolarization.8–10 This collectively causes the heart to contract quicker and stronger. 5. Removal of Alternatively, the neurotransmitter can stimulate a pro- 4. Binding to norepinephrine tein to perform a certain intracellular function. Serotonin, a receptor Norepinephrine Synaptic space neurotransmitter found primarily in the gastrointestinal tract, is also present in platelets and within the brain. Serotonin, released by damaged platelets, causes arterial and venous con- striction; this is thought to be one of the causes of migraine headaches.11–14 Intracellular response Serotonin within the brain is primarily located in the hypothalamus, where it affects sleep, temperature, pain Figure 30-1 The cycle of neurotransmission. Pharmacological Interventions for Cardiopulmonary Emergencies 639 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Agonist drugs

work by either increasing the amount of antidepressants; albeit rarely. Physostigmine is an example neurotransmitter (a direct effect) or decreasing the amount of a parasympat homimetic, a drug that mimics the action of of re-uptake or enzymatic degradation, thereby indirectly the parasympathetic neurotransmitter acetylcholine. increasing the amount of neurotransmitter. In both cases, Another anticholinesterase drug with parasympathomi- these drugs would be considered an agonist. metic properties is neostigmine bromide. Neostigmine is used Alternatively, a drug can act to block the neurotransmitter, to help reverse the effects of certain neuromuscular blocking and thus act as an antagonist. Drugs in this class work by either agents, called paralytics, which are used during emergencies decreasing the amount of neurotransmitter, increasing enzymatic to facilitate intubation.19 destruction of the neurotransmitter, or by competing with the neurotransmitter for the receptor, called competitive inhibition. Anticholinergic Agents Cholinergic Receptors Cholinergic blockers, those drugs that block acetylcholine Acetylcholine attaches to cholinergic receptors within the para- from binding to either muscarinic or nicotinic receptors, are sympathetic nervous system. These cholinergic receptors can called anticholinergics. Drugs in this classifi cation would be further divided into muscarinic and nicotinic receptors. stop parasympathetic activity. Originally, the muscarinic receptors were identifi ed for Antimuscarinic drugs inhibit parasympathetic activity their affi nity for muscarine, a poison found in mushrooms. at the muscarinic receptors. Their greatest impact is on the Five different muscarinic receptors (M1-M2-M3-M4-M5) core organs, such as the eyes, the gut, and the heart, because have been subsequently identifi ed.15,16 For example, M2 recep- peripheral skeletal muscle primarily has nicotinic receptors. tors have been found in the cell wall of cardiac muscles. An example of a muscarinic blocker is atropine sulfate. Nicotinic receptors, the other cholinergic receptor, are Atropine sulfate is a plant alkaloid derived from the deadly located in the adrenal medulla, the central nervous system, nightshade plant (latin—atropa belladonna).19 Its fruit, a and at many neuromuscular junctions, such as the muscles small black cherry, is poisonous. It was used, in small quan- within the bronchioles. Similar to muscarinic receptors, nico- tities, by Ladies of the Court in medieval Italy to add “bril- tinic receptors were identifi ed for their affi nity to nicotine. liance” (pupil dilation) to their eyes; hence the name “bella Blockage of the nicotinic receptors, an antagonist effect of donna” or beautiful lady. The name “atropine” comes from drugs like pancuronium, results in smooth muscle paralysis, the Greek atropos, one of the Fates who held the shears to cut diaphragmatic paralysis, and respiratory arrest. the thread of life. This reference is interesting in light of the The main neurotransmitter that connects with either fact that atropine is used to treat life-threatening bradycardia. a muscarinic or nicotinic receptor is acetylcholine. Any Atropine’s effect is to block the vagus nerve (parasympathetic chemical that mimics the action of acetylcholine (e.g., nic- nerve) in the heart and reduce the vagal tone that slows the heart, causing the heart rate to rise.20 otine) is said to be a parasympathomimetic agent. Poison mushrooms often contain muscarinic-like chemicals that are Because it is a parasympathetic blocker, atropine also cholinomimetic.17,18 decreases saliva production in the mouth, leaving the mouth dry (xerostomia). This effect is desirable prior to intubation. Atropine is also used as a pretreatment to prevent bradycardia Cholinergic Agents induced by vagal stimulation of the hypopharynx, which is The action of acetylcholine on the heart is to slow its rate occasionally seen during pediatric intubation. through direct stimulation of the vagus nerve. Any drug Atropine has received more interest lately as an antidote which has a similar action, that mimics the effects of acetyl- for certain nerve agents used as weapons of mass destruction. choline, would be called a cholinergic drug. Drugs of this sort These nerve agents are structurally similar to the organophos- usually have a subcomponent of acetylcholine, such as an phate fertilizers. This treatment works by blocking parasym- ester or alkaloid-like molecule of acetylcholine, which binds pathetic receptors. Atropine is now available in auto-injectors directly to the cholinergic receptor. Pilocarpine is a drug in for deep IM injection during an exposure to these deadly this classifi cation. nerve gasses.21–24 Using an alternative mechanism to increase the amount The alternate anticholinergic is the nicotinic blocker. of naturally occurring acetylcholine available, some drugs Nicotinic blockers have been used for decades in the operat- bind with the enzyme that breaks down the acetylcholine ing room as a muscle relaxer. The earliest nicotinic blocker, (acetylcholinesterase), thus rendering the enzyme inert. As curare, owes its origin to tribesmen in the equatorial Amazon. a result, less acetylcholine is broken down and there is more These tribesmen would easily bring down large animals, acetylcholine available in the synaptic junction. An exam- without killing them, by arrows that were dipped in curare. ple of a drug that uses this mechanism is physostigmine, The animal was seemingly paralyzed and died from suffoca- a drug used to treat open-angle glaucoma. Papillary con- tion while still awake. In the 1850s, Claude Bernard showed striction (miosis) is controlled by the parasympathetic ner- that the South American Indian drug curare worked primar- vous system. Physostigmine is also used to treat overdoses ily at the neuromuscular junction and that a substance, later of atropine (whose action is discussed later) and tricyclic identifi ed as acetylcholine, was blocked from receptors on 640 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. the muscle cell. The idea that cells had receptors which could Adrenergic Neurotransmitters be affected by drugs had wide ranging implications for phar- Adrenergic neurotransmitters function in a manner similar to maceutical research.20 cholinergic neurotransmitters except that they act on the sympa- Curare was a crude cholinergic blocker that was spe- thetic nervous system. In the sympathetic nervous system nor- cifi c to the nicotinic receptors found in skeletal muscle. By epinephrine, not acetylcholine, is the primary neurotransmitter. blocking acetylcholine from attaching to nicotinic receptors Similar to the process in the parasympathetic nervous on skeletal muscle, the muscles were, in effect, paralyzed. system, the sympathetic (adrenergic) nerve produces norepi- The advantages of a drug which could paralyze are numer- nephrine. To produce norepinephrine, the neuron takes the ous. For example, a paralyzed patient is easier to intubate amino acid tyrosine and synthesizes it into dopamine, which and mechanically ventilate.25–27 Used together with sedatives is in turn converted into norepinephrine in the vesicles. and analgesics, these drugs have created an ideal intubation Norepinephrine is released from the vesicle, by an infl ux condition. Paralytics, as a class, do not cross the blood-brain of calcium that occurs with neuronal stimulation, and fl oods barrier easily. Therefore, while the patient is paralyzed, he the synapse between the nerve and the target cell. Attracted remains completely awake and sentient (sensing surround- to adrenergic receptors on the cell wall membrane, the nor- ings) and can experience feelings of pain. It is standard epinephrine binds with the cell receptor and activates the practice to co-administer a sedative and/or pain medication enzyme adenyl cyclase, in a second messenger system, to (analgesic) along with the paralytic agent to decrease the convert adenosine triphosphate (ATP) into cyclic adenosine patient’s anxiety and relieve discomfort while paralyzed. monophosphate (cAMP), releasing two phosphate molecules Some paralytics, particularly the early nondepolarizing in the process. The two liberated phosphates are an energy- agents, release histamine, a vasodilator, from the mast cells in rich substrate which is used by many proteins within the cell the blood. Therefore, the patient’s blood pressure would fall. to power metabolic processes (Figure 30-2). The next generation of paralytics (e.g., pancuronium) does not After having caused the intended effect, the norepineph- release histamine and therefore is more useful when treating rine is released from the receptor and may either diffuse into patients at risk for hypotension, such as the trauma patient. the general circulation or be taken up again by the adrenergic neuron. Depolarizing and Non-Depolarizing The norepinephrine, assisted by an ATPase (enzyme), re- Neuromuscular Blockers enters the neuron where it can either be stored in a vesicle or broken down by monoamine oxidase (enzyme) into inactive Neuromuscular blockers can be classifi ed as either depo- by-products (metabolites). larizing or non-depolarizing. Depolarizing agents attach to the nicotinic receptor at the neuromuscular junction. In the Adrenergic Drugs resting state, the cell has charged sodium ions on the outside and potassium ions on the inside of the cell. This results in a It is important for the Paramedic to understand the sympa- difference in the electrical potential between the outside of thetic response because many drugs owe their therapeutic the cell and the inside. This difference is called the resting effect to the impact of these adrenergic drugs in the process of membrane potential. With the nicotinic receptor stimulated neurotransmission. For example, cocaine prevents the uptake by the drug, the cell opens the sodium channels in the cell of norepinephrine, thereby causing a buildup of norepineph- wall and a rapid infl ux of sodium occurs. This results in depo- rine in the synapse, and hyperstimulation of the cell.28,29 larization and subsequently causes a cascade of events which Norepinephrine is an important neurotransmitter in the then cause muscular contraction. These transient fi ne muscle central nervous system (CNS). Inhibition of uptake of norepi- contractions, seen after administration of a depolarizing neu- nephrine by tricyclic antidepressants, or the blockade of mono- romuscular blocker, are called fasciculations. amine oxidase (MAO) breakdown of norepinephrine by MAO The depolarizing paralytic agent, however, remains bound inhibitors, can improve clinical depression, for example.30 to the receptor, unable to be broken down easily by the nor- There are two adrenergic receptors in the sympathetic mal enzymes. This persistent action of depolarizing agents nervous system: the alpha-receptors and the beta-receptors. prevents the repolarization of the cell and a return of the cell These adrenergic receptors are further divided into alpha or 1 to its normal resting state. Instead, the cell and the muscle alpha according to the organs on which they predominate 2 remain fl accid (unable to be stimulated) and paralyzed. (Figure 30-3). For example, beta receptors are found on car- 1 As an alternative, non-depolarizing paralytic agents also diac muscle cells whereas beta receptors are found on arte- 2 bind with the nicotinic receptor but do not have the same rial smooth muscle and bronchial smooth muscle.31–33 effect on the cell. These agents simply bind to a receptor with- out causing depolarization. With the receptor site occupied, Adrenergic Agents the cell remains in a ready resting state. However, the cell is Several drugs have been created which mimic the effects unable to be stimulated because the receptor is blocked. This of the sympathetic neurotransmitter norepinephrine. These prevents the unwanted muscular fasciculations seen with drugs are called sympathomimetics. Sympathomimetics depolarizing agents. (often either prodrugs or analogs of norepinephrine) share a Pharmacological Interventions for Cardiopulmonary Emergencies 641 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Presynaptic neuron isoproterenol—all have similar effects on the cardiovascular Direction of conduction system.34 These drugs elevate blood pressure and thus are of nerve impulse also called vasopressors. However, each drug has an action Vesicles containing that is slightly different from the others, thus making one neurotransmitters more desirable than another for different circumstances. The indirect adrenergic agonists are stimulants that cause Mitochondrion the release of norepinephrine. An example of an indirect adren- Synaptic ergic agonist is the class of drugs called amphetamines. cleft Systemic Pharmacologic Effect Owing to the widespread distribution of adrenergic receptors in the major core organs, and the often dramatic effect these sympathomimetic drugs can have upon the sympathetic ner- vous system, a

review of systems will be discussed. The heart may be the organ system most affected by adrenergic agonists. These powerful medicines can markedly increase the heart’s strength of contraction (positive inotro- pic effect) as well as rate (positive chronotropic effect) as a result of increased calcium infl ux in the myocardium. The calcium infl ux causes a higher action potential and quicker depolarizations. Left alone, stronger, faster contractions lead to more complete ventricular emptying and an increased car- Postsynaptic Receptors on postsynaptic neuron membrane bound to neurotransmitter diac output. Catecholamines, such as epinephrine, can be potent car- Figure 30-2 Neurotransmission. diac stimulators. This is the anticipated action of epinephrine during a cardiac arrest. Epinephrine should either (1) increase common base molecule, a catechol ring. Thus, they share a the fi brillatory action of the arrested heart, coarsening the drug classifi cation, and are called catecholamines. ventricular fi brillation, so that subsequent defi brillations are All catecholamines are very potent adrenergic agonists more likely to be successful, or (2) induce spontaneous pace- because they can cause a direct response from the adrener- maker activity in the heart in cardiac standstill (asystole). gic receptor. In fact, most catecholamines, such as dopamine Conversely, catecholamines like epinephrine, when inap- and epinephrine, have naturally occurring counterparts in the propriately administered, can induce spontaneous depolar- body. Because of this, the body also has a means of breaking izations and extra-systoles by the same mechanisms. These down the drug more rapidly; in this case, with the enzymes actions can disrupt a normal cardiac sequence and send the monoamine oxidase (MAO) and another enzyme called heart into chaos and ventricular fi brillation. catechol-O-methyltransferase (COMT). In order to maintain The peripheral capillary beds are largely controlled a therapeutic effect, these drugs are continuously infused by alpha receptors of the sympathetic nervous system as 1 intravenously. The infusion is then slowed, a process called well.35,36 During times of stress, when blood is needed in the weaning, to the point where the body is able to sustain itself core organs, these capillary beds can be preferentially shut and is no longer dependent on the infusion to maintain vital down. Blood will then be directed toward the body core in a functions such as blood pressure. process called shunting. This shutdown of capillary beds also Realizing the limitations of catecholamines, newer non- causes a higher total peripheral vascular resistance (PVR) to catecholamine compounds have been created (i.e., those forward blood fl ow. without catechol ring). Without the ring, the enzymes COMT In certain abnormal perfusion states, such as anaphylactic and MAO have more diffi culty neutralizing the drug into shock or septic shock, peripheral vascular resistance is reduced. an inactive metabolite. Therefore, these drugs enjoy a lon- Then catecholamines, such as dopamine or norepinephrine, ger duration of action. Ephedrine, a common ingredient in can help to restore a higher PVR. decongestants, is an example. Administration of catecholamines, such as dopamine, Adrenergic agonists may work by direct action or by can result in a higher PVR through alpha receptor stimula- 1 indirect action. Direct acting adrenergic agonists couple with tion. While dopamine is a very useful drug when used appro- and excite the adrenergic receptors. The indirect agonists priately, a high PVR presents an obstacle to forward blood cause the release of norepinephrine from the terminal neu- fl ow from the heart (i.e., cardiac output). This effect can cre- ron, which in turn causes the norepinephrine to attach to the ate such a large demand on the heart’s muscle that it cannot adrenergic receptors and the receptors to react. keep up with demand and the patient may manifest symptoms The five direct-acting adrenergic agonists— such as chest pain (angina) and possibly sustain a myocardial norepinephrine, epinephrine, dopamine, dobutamine, and infarction. 642 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Pupils dilate Mobilization of glucose Increased heart rate Relaxation of bronchial tree Release of epinephrine by adrenal gland Slowdown of digestive process 8910010110760 20 114300Increased 0 0 blood pressure Figure 30-3 The effects of adrenergic receptor stimulation. The differences between the effects produced by each of the catecholamines, and even the differences between the Street Smart effects of a single catecholamine at different doses, requires careful monitoring of the patient for untoward effects. The smooth muscles of the bronchi and the bronchioles Topically applied, epinephrine and epinephrine are also richly supplied with beta receptors and are easily derivatives such as phenylephrine can create a 2 affected by catecholamines. When activated, these receptors localized vasoconstriction in exposed capillary beds in cause dilation of medium-sized airways. This positive effect the mucosa. A solution sprayed into the nasal mucosa is so pronounced that these agents have become a mainstay in the treatment of bronchoconstriction and are discussed in of the nostril prior to intubation can reduce the more detail in the section on drugs that affect the respiratory likelihood of bleeding during a nasal intubation.37,38 system. The key to successful use of these agents is to apply One of the notable effects of catecholamines on the them before other lubricating substances and in time endocrine system is the increase in the amount of blood glu- cose available to be used as energy. This is achieved through for the medication to take the desired effect. Upon a combination of decreased insulin secretion from the pan- quick visualization, the mucosa should appear pale creas and increased breakdown of glucagon in the liver and after vasoconstriction has occurred. muscles. The intended effect of the elevated blood glucose Pharmacological Interventions for Cardiopulmonary Emergencies 643 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. levels is to have more fuel for an active metabolism during (beta selective agents). Cardioselective drugs, such as 2 an emergency. atenolol, only affect the heart, which predominantly has beta receptors, and prevent catecholamine-stimulated tachy- 1 Alpha-Adrenergic Blockers cardia. This effect can have a signifi cant impact on mortality Most alpha-adrenergic blockers are competitive b lockers, and infarction size during acute coronary syndrome. occupying the adrenergic receptor and preventing the Beta-blockers, particularly nonselective beta-blockers, catecholamine drug from attaching to the adrenergic receptor. are used to treat hypertension. These beta-blockers, such as Alpha-adrenergic blockers can be divided into either long- propranolol, prevent peripheral vasoconstriction and subse- acting and short-acting or competitive and noncompetitive. quent increased peripheral vascular resistance with the over- Noncompetitive antagonists are longer acting and generally all result of a lower blood pressure. used for special conditions. For example, a pheochromocytoma, Caution should be advised any time a beta-blocker is a tumor of the medulla of the adrenal gland, can induce life- given to a diabetic patient. Beta-blockers can mask many of threatening hypertensive crisis through secretion of high doses the classic signs of hypoglycemia. Concerns about hypogly- of epinephrine. The use of longer-acting alpha a ntagonists, cemia, secondary to history or physical, should be followed such as phenoxybenzamine, can reduce dangerously high up with a blood glucose measurement. blood pressures. Longer-acting alpha antagonists are also used to relieve the symptoms of benign prostate hypertrophy (BPH). BPH is a common consequence of aging for men. Alpha-adrenergic Street Smart blockers relax the bladder muscles, allowing for a greater passage of urine. A patient who is under treatment for BPH Sudden withdrawal of a beta-blocker may result with a long-acting alpha antagonist, who subsequently needs hemodynamic support from a catecholamine infusion, such in symptoms of an acute coronary syndrome, as dopamine, will not respond as briskly secondary to com- including chest pain (angina), rebound hypertension, petition from the alpha-adrenergic blocker. tachycardia, and bronchospasm. Patients on beta- Competitive short-acting alpha antagonists, such as blockers should be weaned off the medicine slowly to phentolamine, are more commonly used to treat acute hyper- tensive crisis, especially hypertension secondary to a pheo- prevent these symptoms. Prehospital treatment may chromocytoma. Its emergency application can also prevent include re-instituting the beta-blocker intravenously acute hypertension and stroke secondary to an overinfusion until the patient stabilizes. Only a complete drug of a catecholamine, such as a “runaway” dopamine infusion. Cerebral vasoconstriction is thought to be one of the history would reveal that the patient’s symptoms are causes of migraine headaches. Logically, an alpha blocker the result of suddenly not taking his beta-blocker. would prevent or reverse any vasoconstriction created by the sympathetic nervous system. Ergot is an alpha-adrenergic blocker used to treat both dementia and migraine headaches. A plant alkaloid, ergot is extracted from a fungus which grows Pharmacological Interventions on rye. Another extract of note from this extraction is lysergic acid diethylamide (LSD). during a Respiratory Emergency Ergot compounds are thought to depress the central ner- The pulmonary system, starting at the pharynx and end- vous system’s vasomotor centers and thus inhibit the pulsa- ing in the capillary beds surrounding the alveoli, through tions, described as pounding by the patient, characteristic of mechanical ventilation and pulmonary respiration, is a migraine.39,40 Ergot compounds do not treat migraines, they responsible for oxygenation, removal of wastes (including only prevent them from occurring and thus must be taken early carbon dioxide), and the regulation of acid–base balance. during the aura phase in the attack in order to be effective. When any one of these functions is disrupted, illness and even death can ensue. Airfl ow into the lungs is partially con- Beta-Adrenergic Blockers trolled by the diameter of the airway passages, the absence Beta-adrenergic blockers, more commonly called beta- of obstructions, and proper air pressure gradients. Of these, blockers, can be divided into two classes: selective and non- the diameter of the airway may be most important. The air- selective. Nonselective beta-blockers inhibit both beta and ways within the tracheobronchial tree are surrounded by 1 beta receptors by direct competition with norepinephrine smooth muscle arranged in a double helix, like a Chinese 2 for available receptors. This mixed effect can be problematic fi nger-trap, which expands and contracts. This increases or depending on the desired therapeutic outcome. decreases the airway’s lumen. Beta-selective drugs specifi cally target either the heart, All muscles within the body are controlled by the ner- and are referred to as cardioselective, or target the lungs vous system, and the muscles in the airway are no exception. 644 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Parasympathetic nerves (from the vagus nerve) narrow the airway’s lumen, called bronchoconstriction, while the sym- Street Smart pathetic nerves widen the airway, called bronchodilation. Some OTC medications used to self-medicate asthma Overview of Pulmonary have epinephrine as their main ingredient (e.g., Pathophysiology Primatene Mist™). In an effort to obtain relief from The majority of pulmonary diseases can be linked to what the asthma symptoms, patients may not follow is referred to as the “three S’s”: spasm, swelling, and secre- tions. Bronchospasm, as manifested in the wheezing of an medication instructions on the package insert. asthmatic patient, is a narrowing of the airway or broncho- As a result, undesirable cardiotoxic effects can constriction.41 This bronchoconstriction is the result of stim- arise, including chest pain (angina) and myocardial ulation of the muscarinic receptors of the parasympathetic nervous system. infarction from the resulting beta-adrenergic Any irritant, such as pollen and aerosolized medications, overstimulation. can stimulate this protective airway refl ex. The muscarinic

receptors, in turn, stimulate the production of cyclic GMP, which causes the muscle contraction and subsequent broncho- to be administered by inhalation, injection (sublingual), or constriction. Cyclic GMP can also cause the release of chemical intravenous infusion, isoproterenol does not have the alpha mediators from mast cells, such as histamine and leukotrienes. effects of epinephrine. However, it still causes the same car- One common bronchospastic respiratory illness treated diotoxic effects. by Paramedics is asthma. Asthma is a potentially reversible airway spasm that is triggered by a stimulus. The stimulus Beta-Selective Drugs can either be an internal or intrinsic trigger, such as stress or Improvements and refi nements have led to a group of exercise, or it can be an external or extrinsic trigger, such as drugs that is more highly selective for beta receptors and 2 pollen, dust, and mold. has little or no impact on beta receptors. These drugs are 1 The severity of a patient’s disease can be classifi ed called beta-selective adrenergics. The fi rst beta-selective according to the frequency of exacerbations experienced. adrenergic drug (isoetharine) was still a direct-acting cat- An occasional exacerbation or asthma attack (less than once echolamine derivative (i.e., sympathomimetic), but had or twice a week) is considered mild intermittent asthma and weak beta properties. 1 is treated with episodic medications intended to treat bron- The next generation of beta-selective drugs was non- chospasm and infl ammation. More frequent attacks, and catecholamines. Non-catecholamine drugs had signifi cant particularly those which occur while asleep, are treated with advantages over earlier catecholamine-based drugs. The routine medications on a daily basis in an attempt to prevent body has enzymes, such as MAO and COMT, to break cat- bronchospasm and infl ammation. Persistent bronchospasm echolamines down at the neuromuscular junction. The non- that is resistant to routine treatments, called status asthmati- catecholamine drugs were not as strongly affected by these cus, can lead to suffocation and death and must be treated enzymes and thus their effects tended to last longer. The non- aggressively.42–45 catecholamine drugs were also more discriminating, having An asthma exacerbation can be treated with an aerosolized primarily beta effects and almost no beta effects. 2 1 beta-agonist, often called a “rescue drug,” such as albuterol. The importance of immediately administering rescue drugs to an asthmatic patient in distress cannot be understated. Street Smart The earliest treatment for asthma, sympathomimetic epinephrine, is still used today. Whether given subcutane- ously or inhaled, epinephrine proved effective in reversing Terbutaline causes the relaxation of the smooth bronchospasms, and every other rescue drug since has been muscles in the bronchial tree, the blood vessels of some derivative of epinephrine.46 Epinephrine is not without skeletal muscle, and the uterus. Uterine its side effects. A nonselective adrenergic stimulant, epineph- contractions during labor can be slowed, a process rine causes tachycardia and palpitations (the feeling of one’s own heart racing), peripheral vasoconstriction (which raises called tocolysis, by administration of terbutaline. the PVR and the work of the heart), as well as restlessness, This effect may be useful in cases of high-risk anxiety, and insomnia. pregnancy or delays in transportation to a The next generation of asthma medications is intended to reduce these undesirable side effects. They still affect the tertiary care center (e.g., during a snowstorm beta receptors. The prototypical medication in this class, or fl ood). 2 a nonselective beta-adrenergic drug, is isoproterenol. Able Pharmacological Interventions for Cardiopulmonary Emergencies 645 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. The model non-catecholamine beta-selective drug is albuterol. Albuterol stimulates the beta receptor to produce 2 Street Smart the cAMP, which results in smooth relaxation without stimu- lating the heart to race (beta effect) or the blood pressure to 1 rise (alpha effect). The metered dose inhaler form of ipratropium was 1 made with components similar to peanuts and was Xanthine Derivatives not recommended for use in the peanut-allergic patient in the past. Presently the metered dose The active ingredient in coffee and teas is caffeine, another plant a lkaloid, which is perhaps the most widely used stimu- inhaler form of ipratropium has been reformulated lant in the world. Caffeine, a xanthine derivative, relaxes with a non-peanut based propellant and is safe for smooth muscle in the bronchial tree, stimulates the heart, and use. The premixed nebulized solution of ipratropium stimulates the CNS. More discussion about caffeine can be found on the section on drugs which affect the CNS. does not contain these components and is safe and The liver converts xanthines, as a prodrug, to theophyl- benefi cial to the patient experiencing an acute line, which causes bronchodilation. For a variety of reasons, bronchospastic airway reaction. most notably cigarette smoking, the conversion to theophyl- line can be unpredictable and toxicity is not unusual. As a class, xanthines work by inhibiting an enzyme (phosphodiesterase), which results in an increase in cAMP Prophylactic Medications and GMP, which in turn alters calcium levels in the muscle for Pulmonary Disease as well as blocking adenosine receptors. The end result is The actions of prophylactic asthma medications generally bronchial dilation. Methods of administration of theophyl- revolve around decreasing infl ammation (specifi cally, prevent- line compounds include orally in a liquid, intravenously as ing the degranulation of mast cells) and subsequent releasing of an infusion, and rectally as either a suppository or a reten- histamine, prostaglandins, and leukotrienes (leukotrienes were tion enema. known as slow reaction smooth muscle-stimulating substance Unfortunately, xanthine derivatives interact with several (SRS)—the name is descriptive of the action of leukotrienes). other commonly prescribed drugs. For example, phenytoin, Histamine and leukotrienes cause swelling, bronchospasm, a commonly prescribed anticonvulsant, causes an increase and subsequent narrowing of the lumen of the airways. in xanthine metabolism, leading to subtherapeutic levels of Cromolyn, a mast cell stabilizer, inhibits the release of xanthine as well as lower levels of phenytoin. Subtherapeutic histamine, prostaglandins, and leukotrienes from mast cells, levels of phenytoin for patients with a seizure disorder can in part, by stabilizing the cell wall via blockage of calcium result in a breakthrough seizure. ion channels in the cell wall. Cromolyn is therapeutically Cigarette smoking, mentioned earlier, also interferes equal with a maintenance dose of theophylline and has fewer with theophylline metabolism. The dose of theophylline for side effects than theophylline. For this reason, cromolyn has smokers has to be increased between 50% and 100% because largely replaced theophylline as a prophylactic agent for the of increased metabolism. Due to the unpredictable therapeu- treatment of asthma. tic level, the narrow therapeutic index, and undesirable side A new class of anti-infl ammatory drugs, called leuko- effects, theophylline use has markedly decreased as newer triene antagonists, are becoming available. Drugs in this class medications with more tolerable side effects have been proven block leukotriene receptors. Leukotriene is the slow-acting equally effective. substance of anaphylaxis that causes mucous plugs and constricts bronchial airways. Leukotriene antagonists, such as zileuton, have the distinction of affecting all three of the Cholinergic Antagonists “S’s” of pulmonary disease (swelling, secretions, and spasm). As a class, cholinergic antagonists are not as effective as Leukotriene antagonists are indicated for the treatment of bronchodilators but rather prevent further bronchoconstric- long-term or chronic asthma. tion by occupying the muscarinic receptors on the bronchial Commonly prescribed inhaled corticosteroids reduce smooth muscle that cause bronchoconstriction. Treatment infl ammation as well, but by a slightly different action. of bronchospasm with anticholinergic medications is most Corticosteroids stabilize lysosomal membranes, preventing effective either immediately preceding the bronchospasm or the release of hydrolytic enzymes which produce the infl am- immediately after treatment with a bronchodilator, to prevent matory response in the tissues, as well as decrease the pro- a return of bronchospasm. Therefore, during the treatment duction of leukotrienes. of reactive airway diseases such as asthma, beta-selective Inhaled corticosteroids have many systemic side effects, adrenergic drugs are preferred. However, concurrent admin- including cough, dizziness, and headache. Newer generations istration of cholinergic antagonists, such as ipratropium, is a of corticosteroids have been developed which reduce some of common practice.47 these unwanted side effects. 646 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Caution regarding corticosteroids is advised. Cortico- nurses out-of-hospital demonstrated the effi cacy of prehospital steroids suppress secretion of hormones from the hypothala- care and ranging to today’s 12-lead ECG technology, EMS has mus, pituitary, and adrenal glands. Sudden withdrawal from always had a focus on cardiac care. corticosteroids can precipitate a potential acute adrenal insuf- The Paramedic’s fi rst mission was and still is to reduce fi ciency, or Addisonian Crisis. Patients taking steroids must dysrhythmic death. The use of cardiac medications, as an be gradually weaned off corticosteroids, by tapered doses, adjunct to rapid defi brillation and cardiopulmonary resus- while the body readjusts. citation, is thought to have had a signifi cant impact on the morbidity and mortality from cardiovascular disease and continues to be the mainstay of advanced cardiac life sup- Mucolytics port. Therefore Paramedics must have an understanding of Thickened secretions in the airway obstruct the airway and the indications and mechanism of action of many cardioac- serve as a breeding ground for infection. These secretions tive drugs in order to effectively and effi ciently treat their are diffi cult to expel (expectorate), leading to partial airway patients and prevent sudden cardiac death. obstructions via mucous plugs, as well as acting as a foci for Today, the mission of EMS is even more complex, infl ammation and infection. For these reasons, it is important and advances in cardiology have added new demands on to clear these secretions from the airway. Paramedics. Paramedics must not only understand the drugs Mucus is made up of a combination of protein-like mate- which prevent or treat cardiac arrest, but also drugs that are rials, and complex sugars called polysaccharides. Sputum, used in the treatment of acute myocardial infarction. mucus with cellular debris such as white blood cells (leuko- In the past the diagnosis of a “heart attack” (acute myo- cytes) and bacteria, is largely made up of water. By adding cardial infarction) was viewed as an inevitable death sentence. physiologic saline (0.9% sodium chloride in sterile water) to Today, new drugs, such as fi brinolytics, and new technologies, the airway, via aerosol or bolus fl ush, the thinned sputum is such as angioplasty, can literally halt the myocardial damage, easier to remove by suction. but only if the patient can obtain these treatments in time.48 Ridding the airway of thickened secretions, called pulmo- This changing focus from dysrhythmic death (mortal- nary toilet, can also be achieved through sterile endotracheal ity) to myocardial salvage (morbidity) has even changed the suctioning, hydration (oral or intravenous), and administra- nomenclature. Acute myocardial infarction, an event once tion of drugs which thin the secretions, called mucolytics. seen as occurring in isolation, is now looked upon as a part of Mucolytics physically break down the viscosity of mucus the acute coronary syndrome (ACS). ACS is a complex of by breaking apart the mucoprotein structure. An example of a symptoms associated with the continuum of cardiovascular commonly used mucolytic is acetylcysteine which is absorbed disease, emphasizing its morbidity (and more importantly, its directly into the airway and exerts a local effect. Acetylcysteine mutability) and not simply its mortality.49–51 begins to work within one minute and peaks in as little as 5 to 10 minutes, destroying the mucoprotein structure of mucus and allowing for easier expectoration. Coronary Artery Disease Coronary artery disease is primarily due to atherosclerosis. Unchecked, atherosclerosis blocks coronary arteries, which Pharmacological Interventions leads to hypoperfusion distal to the occlusion and death of the during a Cardiac

Emergency cardiac muscle tissue, acute myocardial infarction (AMI). The series of events that leads up to and includes the myo- Over 60 million Americans have cardiovascular disease and cardial infarction is referred to as coronary artery disease over 12 million Americans have coronary artery disease. (CAD). Over 7 1/2 million of those Americans will have an acute Atherosclerosis, the underlying pathology of coronary myocardial infarction (AMI) and over one million will not artery disease, starts as a streak of fat (cholesterol) on the survive the event. Additionally, nearly fi ve million will have walls of an artery, any artery. This includes the cerebral arter- congestive heart failure.20 ies as well as the coronary arteries. The fat infi ltrates into These fi gures serve to illustrate the prevalence of car- the wall of the artery, below the tunica intima, and forms diovascular disease and its impact upon Americans. In fact, a fatty lesion referred to as plaque. The plaque has a thin cardiovascular disease has been the number one killer in the fi brous covering, created by the tunica intima, called the cap. United States since 1918, with the exception of the year of This bulges into the lumen of the artery, partially obstructing the great infl uenza outbreak. blood fl ow. As the major health issue in the United States for the The presence of nitric oxide (NO), created in endothe- past nine decades, great efforts have been made to reduce the lium of the walls of the blood vessel, which prevents vaso- number of deaths, many of them out-of-hospital, from car- constriction; and heparin sulfate, an anticoagulant released diovascular disease. In fact, the genesis of EMS is owed, in from the endothelium of the walls of the arteries, temporar- part, to cardiovascular disease. Beginning with Dr. Pantridge ily prevents blood clot formation in the narrowed coronary in Belfast, Ireland, whose experiment with using coronary care arteries. Pharmacological Interventions for Cardiopulmonary Emergencies 647 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. As time progresses, macrophages and T-lymphocytes, if the blood vessel had been ruptured, or cut, and attempt to defender cells in the circulation, enter the plaque and begin plug the breach. the process of phagocytosis, literally enveloping the choles- The response to the rupture begins with the attach- terols and fats (lipids) in an effort to destroy the invaders. The ment of von Willebrand’s factor and ADP released from now engorged macrophages swell and become foam cells. inside the plaque to glycoprotien (Gp)IIB/IIIA receptors Foam cells are fi lled with dead and dying muscle cells and found on passing platelets. The now “activated” platelets lipids. Proteins entrapped within the toothpaste-like liquid change from a disc shape to a sphere shape and attach to lipid core also begin to form collagens and von Willebrand’s the exposed collagen and to each other. The eventual mass factor, two elements in clotting. of platelets forms a platelet plug. Platelet plugs are the Plaques, especially newer, less mature plaques, are softer, short-term solution to the problem. have a thinner cap, and are prone to rupture. Any hemody- For a more stable blockade, the platelet plug needs to be namic stress (e.g., a sudden increase in blood pressure) can reinforced. The entire process, from platelet plug production cause a plaque to rupture (Figure 30-4).52–55 to the reinforcement of the thrombus, is called coagulation. When a plaque ruptures and the thin cap is torn, the Coagulation starts when coagulation factors—adenosine uplifted plaque now exposes the collagen in the basement diphosphate (ADP), serotonin, and thromboxane (TxA2)— layer underneath the endothelial lining. Blood clotting fac- are released from the damaged endothelial wall, which trig- tors in the plasma, attracted to the exposed collagen, react as gers a series of events, called the coagulation cascade. Cross sections through a coronary artery undergoing progressive atherosclerosis and arteriosclerosis Small atheroma Normal artery with open Elevated cholesterol Enlarging atheroma lumen and blood fats (plaque deposit) Moderate atherosclerotic Moderate narrowing of lumen myocardial ischemia Angina pectoris Occlusion of left coronary artery A myocardial infarction (“heart attack”) on left side of the heart Complete/almost complete Severe acute occlusion, with hardening myocardial ischemia caused by calcium deposition and infarction Figure 30-4 The development of plaque. Plaque rupture occludes the narrowed lumen causing a myocardial infarction. 648 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. First, a fi brous soluble protein called fi brinogen, which to bile; therefore, increasing bile elimination indirectly helps is found fl oating in the blood, becomes activated. Normally to rid the body of cholesterol. An example of a bile sequester- fi brinogen is coated with amino acids that have an outward ing agent is cholestyramine. facing negative charge. As like-charges repel, these negatively Niacin, a water-soluble vitamin, is also occasionally pre- charged amino acids keep the fi brinogen molecules separated. scribed as a lipid-lowering agent. Niacin inhibits the lipolysis When clotting factors are released, a protein-cutting (division of fats) in adipose tissue, which would liberate free enzyme (protease) called thrombin literally clips off the fatty acids.59–61 These free fatty acids would normally be used negatively charged amino acids. Without the negative charge by the liver to create new triglycerides and then cholesterol. repelling the fi brinogen molecules, the fi brinogen clumps In the case of the patient with hyperlipidemia, the added cho- together, becomes strand-like, and forms fi brin. lesterol would also boost the process of atherosclerosis. What follows are two processes, one intrinsic and the Niacin in high dosages, or in persons sensitive to niacin other extrinsic, which result in a mature clot made of plate- (e.g., diabetic patients and those with liver disease), may also lets cross-linked with fi brin and other blood cells in a fi rm cause an anaphylactoid (anaphylactic-like) reaction, including meshwork called a thrombus. With the thrombus in place, pruritus, diffuse skin fl ushing, as well as dysrhythmias. the lumen of the blood vessel is blocked. The reductase inhibitors, a group of drugs referred to as Decreasing the incidence of cardiovascular disease, and “statins” because of the common ending, have grown increas- subsequent acute coronary syndrome, revolves around inter- ingly popular as a treatment for hyperlipidemia. This class of fering with one or more of the processes previously described. drugs inhibits an enzyme, 3-hydroxy-3-methylglutaryl coen- Starting with chemotherapeutic agents which eliminate the zyme A reductase (HMG-CoA), which is essential for the fatty streak on the inner lumen of the artery that signals the liver to make cholesterol. Without the enzyme HMG-CoA, start of atherosclerosis, cardioprotective agents will be dis- the liver cannot make cholesterol and the process of athero- cussed individually. sclerosis is slowed. Patients with liver disease, particularly alcoholics, are at risk for severe side effects from the statin class of lipid-lowering Antihyperlipidemic Drugs drugs, including rhabdomyolysis (a necrosis of skeletal mus- The easiest means to prevent thrombus-induced coronary cle) which may lead to kidney failure. Examples of reductase artery disease is to reduce unwanted lipids which form inhibitors are fl uvastatin, lovastatin, and atorvastatin. plaques at the onset. Despite dietary control, some individuals continue to have elevated lipid levels in the blood (hyperlipi- Anticoagulants demia), possibly due to genetic infl uences. Hyperlipidemia Unchecked, the process of atherosclerosis will eventually is an abnormally high level of triglycerides and cholesterol culminate in plaque formation, plaque rupture, and thrombus which, when uncontrolled, can lead to atherosclerosis. formation via the coagulation cascade. Anticoagulants are Normally, lipids are bound to protein, forming lipo- intended to prevent the formation of a thrombus, which is the proteins (a protein shell around a lipid core), and are found culmination of the coagulation cascade. fl oating in the blood. There are three varieties of lipopro- Anticoagulants include those agents that prevent plate- teins: very-low density lipoproteins (VLDL), low-density let adhesion, fi brin collection, thrombus formation, and other lipoproteins (LDL), and high-density lipoproteins (HDL). Of thromboembolic events. While anticoagulants are discussed the three types of lipoproteins, LDL is considered the most under the acute coronary syndrome, these drugs are used dangerous because of its high cholesterol content, about 50% under the larger umbrella of conditions caused by thrombus cholesterol by weight.56–58 formation including pulmonary embolism, deep vein throm- Some lipid-lowering agents lower cholesterol, thus elim- bus, and thromboembolic ischemic stroke. inating it for conversion to LDL, by sequestering the choles- One of the earliest anticoagulants was salicylate. Extract terol in the bile. The bile is then excreted into the gallbladder of willow bark, salicylate, had long been known for its anal- and, in turn, into the small intestine. Cholesterol is a precursor gesic qualities as “Oil of Wintergreen” (methyl salicylate). However, until Felix Hoffmann eliminated the painful side effect of stomach irritation by reformulating salicylate, it Street Smart was not widely used. Following the reformulation to acetyl- salicylic acid (ASA), the German pharmaceutical company Bayer™ took out a patent and renamed the drug aspirin. Over On the downside, bile-sequestering agents may 80 billion tablets of aspirin are used annually in the United interfere with the absorption of certain medications, States as a pain reliever and fever reducer.62 Thanks in part such as phenobarbital, digoxin, warfarin, and to Bayer™ Company aspirin television commercials, aspirin tetracycline, resulting in reduced subtherapeutic is also widely known for its ability to prevent heart attacks. A study of 90,000 patients showed that aspirin alone pre- levels of these important drugs. vented the reocclusion of coronary arteries in 23% of patients who had a prior AMI, especially if given within four hours.63 Pharmacological Interventions for Cardiopulmonary Emergencies 649 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. As a class, platelet inhibitors prevent platelet aggregation by preventing a critical enzyme, cyclooxygenase, from creat- Street Smart ing thromboxane A2 (TxA2). TxA2 promotes platelet aggre- gation and vasoconstriction. Without TxA2, platelets remain “slippery” and cannot form the initial platelet plug needed for Some EMS systems routinely draw blood samples for thrombus formation. clotting studies, prothrombin times (PT), and partial Prior to administration of aspirin or an aspirin-like prod- prothrombin times (PTT) for analysis in all patients uct, the provider should inquire if the patient has a history who are on an anticoagulant such as warfarin. of asthma. Aspirin-induced asthma (AIA) is present in about 10% to 15% of the patient population with asthma. AIA is an idiosyncratic type of reaction which presents with allergy- like symptoms and is akin to the reaction seen to CT con- Fibrinolytics trast dyes. Treatment with ASA is acceptable for patients with Fibrinolytics dissolve blood clots, which can cause heart asthma, although the patient must be carefully monitored. attacks (acute myocardial infarction/AMI), brain attacks Symptomatic relief should be immediately available if symp- (stroke/CVA), and pulmonary emboli (PE). If successful, the toms should occur. There are several other platelet inhibitors, artery is re-opened (a process called recanalization) and the such as dipyridamole, for those who absolutely cannot toler- blood fl ow is restored to distal ischemic tissue in the affected ate aspirin side effects. organ. The body also naturally produces anticoagulants, such as The fi rst generation of fi brinolytics included uroki- heparin, in the liver, lungs, and lining of the intestine which nase and streptokinase. Initially used to dissolve blood prevent clotting. Circulating heparin helps prevent spurious clots from

long-term, indwelling central venous catheters, blood clots from forming in the body by preventing the for- they were eventually used for the treatment of heart attacks mation of fi brinogen from fi brin. and other thromboembolic events. An unfortunate conse- The addition of intravenous heparin to the body is com- quence of the use of these early fi brinolytics was systemic monly used to help prevent new thrombus formation. It is bleeding. Intracerebral hemorrhage, for example, occurred used as a prophylactic measure post-surgery, to prevent deep with enough frequency that criteria for use of these drugs vein thrombus-induced pulmonary embolism, to prevent was tightened in an attempt to limit this sometimes fatal clot formation during blood transfusion, and to prevent clots complication. from forming on the wall of the heart during atrial fi brillation The second generation of “clot-busters” were more spe- (mural thrombi). cifi c to a newly forming thrombus. These new fi brinolytics It is important to note that heparin does not dissolve used the naturally occurring tissue plasminogen activator pre-existing clots and therefore cannot be used as the sole (tPA) to convert plasminogen into plasmin. Plasmin, a fi brin- therapeutic agent during a thromboembolic emergency. olytic enzyme, dissolves fi brin within the platelet plug. The Other fi brinolytic agents, discussed shortly, are used during a net effect is that tPA disassembles the platelet plug. thromboembolic emergency to actually dissolve a blood clot. Administered intravenously, tPA was an effective and Heparin is often used in conjunction with these fi brinolytic rapid treatment for AMI. It was also relatively inexpensive agents to prevent fresh clots from occurring or to prevent the when compared to the costs of interventional cardiology, current clot from enlarging. such as angioplasty or open heart surgery. Most of the heparin used in-hospital is low-molecular weight (LMWH) heparin. LMW heparin has a longer half-life (t1/2) than standard heparin, permitting daily or twice daily administration, by subcutaneous injection, as compared to stan- Cultural / Regional differences dard heparin, which must be continuously infused intravenously. This quality makes it desirable for outpatient use. The term “thrombolytic” was used for almost a An intravenous infusion of unfractionated (standard) heparin is indicated for use in patients with ST-elevated AMI, decade. However, the more medically correct term is in conjunction with aspirin. LMWH shows promise in the “fi brinolytic.” Both are still used interchangeably in treatment of the patient with a ST-elevated AMI, but its use some medical circles and by the lay public. has not been defi nitively supported in the large scale studies. That said, LMWH is well supported by research for unstable AMI, non-ST elevated AMI and angina.64 Administration of fi brinolytics is not without its dangers. Heparin and its oral counterpart, warfarin, can lead to Caution must be observed before administering fi brinolytics bleeding complications. Once anticoagulants have been to patients with a history of cerebrovascular disease, such as administered, the patient must be monitored for signs of active ulcer disease and recent trauma. Some use a checklist occult hemorrhage, such as tachycardia and hypotension. when administering fi brinolytics (Figure 30-5). 650 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. FIBRINOLYTIC CHECKLIST Rev. 5/07 Central Shenandoah EMS Council, 2312 W. Beverley St., Staunton, VA 24401 • 540-886-3676 • www.csems.vaems.org INCIDENT DATA Date Agency Unit # Patient Name Age DOB INDICATIONS FOR USE OF CHECKLIST Patient experiencing chest discomfort for greater than 15 minutes and less than 12 hours, AND… 12-lead ECG shows STEMI or presumably new LBBB. Are there any contraindications to fibrinolysis? Systolic BP greater than 180 mm Hg YES NO Diastolic BP greater than 110 mm Hg YES NO Right vs. left arm systolic BP difference greater than 15 mm Hg YES NO History of structural central nervous system disease YES NO Significant closed head/facial trauma within the previous 3 months YES NO Recent (within 6 weeks) major trauma, surgery (including laser eye surgery), GI/GU bleed YES NO Bleeding or clotting problem or on blood thinners YES NO CPR greater than 10 minutes YES NO Pregnant female YES NO Serious systemic disease (eg, advanced/terminal cancer, severe liver or kidney disease) YES NO Is patient at high risk? Heart rate greater than or equal to 100 bpm AND systolic BP less than 100 mm Hg YES NO Pulmonary edema (rales) YES NO Signs of shock (cool, clammy) YES NO Contraindications to fibrinolytic therapy YES NO Comments Figure 30-5 Fibrinolytic checklist. Pharmacological Interventions for Cardiopulmonary Emergencies 651 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Prehospital fi brinolytics have been shown to improve coronary syndrome is a process which has many stages, from survival in a few studies and should be considered when intermittent angina to cardiac ischemia to acute myocardial transport times exceed 30 to 60 minutes. Studies continue to infarction. investigate which groups of patients would benefi t the most In most cases, the Paramedic’s job is the early recognition of from fi eld fi brinolytics.65 acute coronary syndrome; stabilization of the patient’s hemody- A growing body of evidence indicates that certain subsets namics and any other complications, such as dysrhythmia; and of patients benefi t more from mechanical revascularization the provision of expeditious transfer of the patient to a cardiac (angioplasty) than standard fi brinolytics. Rapid transportation, care center for further treatment. In some cases, Paramedics with appropriate stabilization, to a cardiac care center may are starting the process of treatment of the coronary artery syn- become the standard of care. Consideration should be given to drome in the fi eld through use of fi brinolytics. In every case, incorporate criterion-based triage into EMS protocols for the whether it is the use of prehospital fi brinolytics or expeditious treatment of the suspected AMI.66 transportation following initial stabilization to a cardiac care center, re-establishing blood fl ow to ischemic myocardial tissue Glycoprotein IIB-IIIA Receptor Blockers is a top priority. Use of nitrates can improve myocardial blood Activation of glycoprotein receptors on platelets and the fl ow, reduce pain, and potentially avert sudden cardiac death. formation of fi brin represent the fi nal common pathway in platelet plug formation. Blocking these receptors prevents Nitrates the binding of fi brinogen and thereby prevents platelet aggre- One of the oldest treatments for cardiac-related angina has been gation and plug formation. nitroglycerin. For centuries, amyl nitrate (a volatile organic The intravenous administration of medications called nitrate when in alcohol) had been used to relieve angina. In glycoprotein IIB-IIIA receptor blockers, like tirofi ban and 1867, the Scotsman Lauder Brunton thought the positive effects eptifi batide, is useful in preventing the re-formation of plate- of amyl nitrate were from hypotension. In 1933, Sir Thomas let plugs and arterial re-occlusion immediately following Lewis more correctly postulated that the effect of amyl nitrate fi brinolysis or angioplasty. was due to dilation of the blood vessels.20 The combination of aspirin (ASA), heparin, and a glyco- However, nitrate’s exact mechanism of action was protein IIB-IIIA receptor blocker can reduce the risk of sud- den cardiac death substantially.67 still unknown until recently. Previously, it was known that some substance, labeled endothelial-derived relaxing factor (EDRF), relaxed the smooth muscle in the walls of blood ves- Acute Coronary Syndrome sels, which in turn led to vasodilation. The involvement of Atherosclerotic coronary plaque growth narrows the blood ves- nitrates in this process was largely unsuspected. sel’s lumen. The narrowing, called a stenosis, causes a reduc- In 1998, Furchgott, Ignarro, and Murad were awarded tion in blood fl ow to the portion of the myocardium distal to the the Nobel Prize in medicine for their discovery of the role of stenosis. Decreased distal coronary artery blood fl ow can lead nitric oxide in human physiology. Nitric oxide (NO), a short- to chest pain, or angina pectoris. Unchecked, these plaques lived gas, is released from endothelial cells within the inner rupture and can lead to complete coronary artery occlusion and lining of the blood vessel where it acts as an intercellular an infarction of myocardium distal to the occlusion. chemical messenger, signaling an increase in cGMP within The entire process leading up to and including angina muscle cells. This increase in cGMP, in turn, relaxes the and AMI is called the acute coronary syndrome (ACS). This smooth muscle in the blood vessel, leading to vasodilation. change in perspective, from treating a heart attack as an iso- It is now known that acetylcholine, the chief neurotrans- lated event to one of treating atherosclerosis as a part of the mitter in the parasympathetic nervous system, acts by stimu- continuum in a common process, refl ects a more considered lating the production of nitric oxide and thereby results in approach to coronary care and refl ects the growing knowl- vasodilation through this mechanism. edge about atherosclerosis and coronary artery disease as a In many cases, coronary artery vasodilation can offer result of practice experience (Table 30-1). symptomatic relief from the cardiac patient’s angina by Syndromes are, according to Taber’s Medical Dictionary, increasing the diameter of a chronically narrowed, stenotic “the sum of signs associated with any pathological process.” vessel. Ironically, Alfred Nobel, inventor of nitroglycerin- In this case, the pathological process is atherosclerosis. Acute based dynamite and originator of the Nobel Prizes, suffered from angina and was prescribed nitroglycerin for his pain. So as to not alarm the pharmacist, the physician labeled the Table 30-1 Inclusion Criteria for Acute nitroglycerin “trinitrin” (TNT). Coronary Syndromes Nitrates administered to a patient provide an exogenous • Unstable angina (external) source of NO. Nitrates have their greatest impact • Non ST-segment myocardial infarction on the venous circulation and reduce venous return, or pre- • ST-segment elevation myocardial infarction (STEMI) load, to the heart. Reduced preload into the heart means less work for the heart’s muscles. 652 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. 5 to 15 minutes. Other side effects include transient hypoten- Street Smart sion, bradycardia or tachycardia, or dizziness.72,73 Nitrate pastes provide a more sustained release of the medication over four to six hours. In contrast, newer time- Fresh nitroglycerin has a slightly vinegary smell and a released patches are formulated with nitrates to create a res- very short shelf life, especially when exposed to light ervoir of medication which can last 1 1/2 to 24 hours. or moisture. Conversely, aspirin has a very long shelf Nitroglycerin is also available in an intravenous form life. In a United States Air Force study, it remained that allows precise titration of the level of drug needed in order to obtain relief from chest pain without the risk of potent for four years. When it breaks down into common side effects, such as hypotension. Intravenous acetic acid, it gives off a slight vinegar smell. Using nitroglycerin is administered in micrograms of drug using an the vinegar smell as a test, the potency of drugs intravenous pump, a biomechanical device that carefully con- trols the rate of administration. Intravenous nitroglycerin (even those within the expiration date) can be is r eadily absorbed into plastic; therefore, special polyvinyl verifi ed. Expired or questionable drugs may not be chloride (PVC) administration sets are used with nitroglyc- potent and should not be used. erin infusion. Nitrate Tolerance Nitrates’

secondary vasoactive effect, particularly at Nitrates, an essential ingredient in smokeless gunpowder, higher doses, is arterial dilation. Arterial vasodilation creates have long been used in munitions production. Workers at the reduced peripheral vascular resistance (PVR), or afterload. munitions factory in places like Springfi eld, Massachusetts, Afterload can be thought of as the resistance which the heart often experienced a headache when returning to work after pump must overcome in order to achieve forward blood fl ow. the weekend. Workers learned that if they took a bag of It is grossly measured as the diastolic blood pressure. nitrate-laced gunpowder home and rubbed it on their hands There is some debate whether nitrates create a coronary they would not experience a headache when returning to work artery-specifi c vasodilation. Coronary vasodilation would after the weekend. increase blood fl ow to oxygen-starved myocardium and What these workers had developed was a classic example lessen the angina.68,69 What is not disputed is nitrates’ ability of tolerance to a drug, in this case nitrate. After continuous to reduce preload and lessen afterload, which culminates in a exposure they developed a resistance to its effects and/or its total reduced workload for the heart. This effect may have the side effects, such as a headache. Whenever these workers greatest impact on relieving the angina.70,71 went home for the weekend, they essentially went on a “drug holiday,” a period without the drug. They then lost their toler- ance to the drug. By continuing their exposure to the nitrate- Street Smart laced gunpowder during the weekend, they ensured that their tolerance for nitrates continued. Patients who are prescribed All patients receiving cardiac medications, nitrates regularly can also develop a tolerance to nitrates and will not respond as well to routine doses of nitrates in the fi eld. particularly vasoactive drugs such as nitrates, need In some cases, it may be advisable to consider an alternative to have constant hemodynamic monitoring, blood therapeutic approach, such as the use of morphine sulfate. pressure, and pulse before and after medication Indications for Nitrate Use administration. The chief use of nitrates is for the relief of cardiac-related chest pain called angina pectoris, or simply angina. Angina is brought Regardless of the primary mechanism, decreased work- about by a mismatch between the work required of the heart load, or coronary artery vasodilation, nitrates have become (workload) and the heart’s ability to do that work. This limita- standard therapy for the patient with angina. In either tablet tion is a function of the coronary blood fl ow to the heart. or spray form, sublingual nitrates have an onset of action of Nitrates are also used to treat pre-infarction angina, for- less than one minute and peak in the bloodstream within two merly known as unstable angina, in an effort to prevent some minutes. With a half-life of only fi ve to seven minutes, any of the damage of coronary artery occlusion. By increasing hypotensive effects created by the venous dilation will sub- collateral blood fl ow to the affected area, distal to the obstruc- side quickly and usually are treated conservatively, at least tion, as well as decreasing the heart’s overall work, the dam- initially, by placing the patient supine for a few minutes. age can potentially be lessened. Nitroglycerin loses its potency when exposed to light, Frequently, physicians and Paramedics assumed that if heat, and moisture. Therefore, it is usually carried in a sealed nitroglycerin relieved the chest pain, then the chest pain must glass bottle with cotton wadding. A commonly noted side be suspected of being cardiac in origin and the likely diagno- effect of nitroglycerin is a transient headache for between sis was coronary artery disease (CAD). Pharmacological Interventions for Cardiopulmonary Emergencies 653 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. A study at Johns Hopkins showed that of 459 patients levels. Life-threatening hypotension then ensues (cardiogenic treated with nitroglycerin for chest pain, all of whom had relief, shock or forward failure). only 30% had coronary artery disease (CAD). The results of this study should cause Paramedics to pause and consider Precautions other potential etiologies of chest pain whenever nitroglycerin Hypotension-induced syncope, or near-syncope, is a com- is effective in relieving chest pain. This is particularly impor- mon complication of nitrate administration.75,76 The impact tant in light of the fact that one in fi ve patients coming to the of the abrupt loss of preload secondary to venous dilation is emergency department complains of chest pain.74 transmitted downstream, the fallout being loss of blood pres- Nitrates have also proven themselves to be markedly sure and possible loss of consciousness (syncope). effective in the treatment of acute pulmonary edema associ- Fortunately, nitrates have a short half-life. Therefore, the ated with congestive heart failure (CHF). CHF is the result hypotensive effects are short-lived. Laying the patient supine of the heart’s inability to pump strongly enough to completely with feet elevated, and exhibiting some patience, are usually overcome peripheral vascular resistance (PVR) and meet the only treatments needed. If the patient’s blood pressure the body’s needs for oxygen and nutrients. Subsequently, does not return within fi ve minutes, then a volume-sensitive backpressure from the left ventricle, or backward failure, is pathology (e.g., internal bleeding or right ventricular myocar- transmitted through the pulmonary circulation, creating pul- dial infarction) should be considered. monary edema in the process, and eventually extending into the right ventricle. The right ventricle, being a weaker pump Dysrhythmia than the left, is overwhelmed by the combination of venous preload and left ventricular backpressure and fails as well. Despite remarkable advances in medicine’s understanding Nitrates are starting to gain increased favor for the emer- of cardiac pathophysiology, and particularly coronary artery gency treatment of pulmonary edema. While loop diuretics disease, over 500,000 Americans will die from heart disease are immediately effective in reducing pulmonary edema, they each year.77 Over 60% of these deaths will be secondary to a can create a hormonal rebound when the kidneys sense the fatal dysrhythmia called ventricular fi brillation. volume depletion and respond naturally to create further fl uid Ventricular fi brillation is one of many dysrhythmias, an retention. The patient with cardiogenic pulmonary edema abnormality of the electrical activity in the heart. Ventricular may not be volume overloaded, but more correctly, volume fi brillation is a life-threatening problem because there is no unbalanced. Nitrates provide the heart with a respite while it cardiac output. regains control of hemodynamics. Street Smart Contraindications In general, any volume-sensitive condition can be worsened Not all dysrhythmias are dangerous. A study of 1,302 by the use of nitrates. Nitrates temporarily remove a volume professional NFL football players completed by of blood from the central circulation by sequestering it in the venous pool. Volume-sensitive conditions can be divided Dr. Choo and Dr. Hutter, Jr., of Massachusetts into cardiac and extra-cardiac pathologies. An example of an General Hospital demonstrated that 55% had an extra-cardiac pathology that is volume sensitive is cardiac abnormality of the electrical activity in the heart. tamponade. However, after extensive testing, it was decided that The heart is dependent on adequate fi lling pressures (pre- the hearts of these athletes were healthy.78 load) obtained from the venous circulation in order to over- come the compressive consequence of pericardial tamponade. Nitrates decrease preload, via venous dilation, and the cardiac output can drop precipitously. Nitrate administration to a patient The most common persistent dysrhythmia may be with a tension pneumothorax can have the same consequence as atrial fi brillation, which affects over two million Americans. a result of a similar mechanism. Atrial fi brillation, a dysrhythmia more often seen in the The right ventricle is acutely sensitive to changes in fi lling elderly, is associated with an increased risk of brain attack volumes (preload). An acute inferior wall myocardial infarction (stroke) and associated quality of life issues. The incidence which extends into the right ventricle can cause the right ven- of atrial fi brillation is expected to rise as the mean age of tricle to lose its ability to pump a given volume of blood. That Americans continues to climb (referred to as the “graying” volume of blood serves as the “prime” for the left ventricle; any of America). pump that loses its prime loses output and fails. The adminis- tration of nitrates decreases the left ventricular fi lling pressures Therapeutic Goal (prime) by reducing preload into the right ventricle from the The therapeutic goal of antidysrhythmics, drugs which venous circulation. Without adequate fi lling pressures, the car- prevent or abolish dysrhythmias, is to alleviate the symp- diac output from the left ventricle can fall to dangerously low toms associated with an irregular heartbeat and, in some 654 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. resting membrane potential of a cardiac cell, measurable at Cultural / Regional differences approximately /()90 millivolts, is created by the rela- tively negative charge inside the cell as opposed to the posi- tive charges outside the cell. In this resting state, the cell wall Technically, an arrhythmia would be defi ned as the is impenetrable to charged ions such as sodium, potassium, absence of a rhythm (a without rhythm pattern) such and calcium. as occurs in asystole. A dysrhythmia would be an A stimulus called an action potential, such as one pro- abnormal pattern of electrical discharges. However, duced by the normal pacemaker activity of the sinoatrial (SA) node, can change the resting membrane potential. it is common practice to use the terms It raises the resting membrane potential above a specifi c interchangeably. threshold. A cascade of ionic changes at the cell wall, called depolarization, occurs as electrolytes transfer across the cell in an attempt to balance (neutralize) the charge. cases, to help ensure the patient’s survival. However, the The cascade of events in depolarization can be divided mechanisms of action of many of the drugs in this class are into fi ve distinct segments, each segment characterized by a also dysrhythmia producing or pro-dysrhythmic. different ionic event and numbered 0 to 4. These different The results of the Cardiac Arrhythmia Suppression Trial segments represent the changes in the electrical charges from (CAST) appear to indicate that there may be a signifi cant within and outside of the cell (Figure 30-6). For simplicity, increase in mortality associated with use of certain antidys- the depolarization of ventricular myocardial cells is being rhythmic drugs. Therefore, the decision to administer an described, although all cardiac tissues—nervous as well as antidysrhythmic must be carefully considered in terms of muscle—respond in a similar fashion. However, nerve cells risk versus benefi t (CAST).The notable side effects of some are more “excitable” (i.e., able to sustain a larger membrane of the dysrhythmia drugs, in addition to the creation of new resting potential). dysrhythmia, have encouraged the development of alternative After the action potential overcomes the resistance cre- therapeutic approaches. ated by the resting potential of the cell membrane (thresh- Some of the devices and techniques in use are radio- old), the sodium channels in the cell wall membrane open frequency ablation to disrupt alternative conductive wide, allowing an infl ux of sodium into the cell. This infl ux pathways, particularly those of supraventricular origin; of sodium, via the fast sodium channels, corresponds with automated implantable cardioverter defi brillators (AICD) phase zero (0) of the action potential and completely depo- with an ability to terminate ventricular tachycardia and ven- larizes the membrane; an event which can be recorded on a tricular fi brillation; and a new generation of dual-chamber surface electrocardiogram or ECG. sensing electronic pacemakers. Use

of these devices and With the now abundant sodium (Na) inside the cell, as techniques have brought about a decrease in the prophy- well as native intracellular potassium (K), the cell becomes lactic use of antidysrhythmic medications.79 positively charged. These ionic shifts within the cell will sur- Nevertheless, antidysrhythmic drugs are still used, par- pass neutrality and the cell wall will become slightly posi- ticularly in the setting of sudden cardiac death (SCD), and tive. This ionic overshoot, about ()20 millivolts, represents will probably continue to be used in the foreseeable future phase 1. to prevent dysrhythmic death and abate symptoms associated To this point, at the end of phase 1, myocardial cells have with dysrhythmia. acted in the same manner as skeletal muscle cells. The difference between skeletal muscle and cardiac muscle occurs in phases 2 Review of Action Potential and 3. In phases 2 and 3, the depolarization of myocardial cells Pivotal to an understanding of the actions of most antidysrhyth- is sustained for about 200 to 300 milliseconds during a “pla- mic drugs is an understanding of the action potential of the teau” phase, unlike the more rapid “spike” of skeletal muscle heart’s muscle cells (the myocardial cells, known collectively as myocardium), which these drugs affect. Myocardial cells are essentially “charged” in a fashion + K+ K+ K K+ K+ Na+ Na+ similar to any conventional car battery. Ionic differences, + K+ K+ K+ K+ K Na+ K+ K+ K+ Na+ Na+ Na+ Na+ K+ Na+ two opposing polarities, between the inside of the cell, repre- Higher Na+ Na+ Na+ K+ + + K+ K+ K+ Na+ K+ senting one pole, and the outside of the cell, representing the K+ K Na Na+ K+ K+ K+ K+ K+ K+ K+ Na+ Na+ Na+ Na+ K+ other pole, are the result of a difference in electron numbers. Na+ Na+ K+ Na+ K+ K+ Na+ K+ Na+ K+ Na+ Na+ K+ Typically this difference would be negated as the additional Na+ electrons are exchanged (neutralized). The cells’ ability to K+ Na+ Na+ Na+ K+ Na+ K+ Na+ K+ K+ Na+ prevent this exchange across the cell membrane is called the Na+ Na+ K+ Na+ K+ higher Na+ Na+ Na+ K+ K+ Na+ Na+ Na+ Na+ Na+ K+ K+ K+ resting membrane potential (RMP). Na+ Na+ Na+ K+ K+ K+ Na+ The greater the electrical difference between poles, or across the membrane in this case, the greater the charge. The Figure 30-6 Action potential of cells. Pharmacological Interventions for Cardiopulmonary Emergencies 655 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. depolarization. This permits a longer sustained contraction. The or ectopic pacemaker. This mechanism, the creation of an key to this sustained contraction is calcium. ectopic pacemaker, is thought to be responsible for sudden In an effort to attain neutrality, calcium fl ows into the cardiac death secondary to ventricular fi brillation. cell, via slow calcium channels, and potassium fl ows out. This is the start of the mechanical activation of the myocardium. Ideal Antidysrhythmic Drug Calcium now binds to the troponin complex, which is found As ectopic pacemakers have been implicated in ventricular within the myocardial fi ber. This normally inhibits the bind- fi brillation, the ideal antidysrhythmic drug would preferen- ing of intertwined actin and myosin strands within the mus- tially select ectopic pacemakers (rapidly depolarizing cells) cle fi ber, and thus permits the sliding (contraction) of muscle over normally functioning myocardial cells and suppress fi bers. The amount of calcium present partly determines the their activity. duration, and therefore the strength, of contraction. The dura- Many of the antidysrhythmic drugs display this ectopic- tion of contraction is represented by the length of the plateau specifi c quality. To explain this phenomenon, Hodgkin and in phase 2. Huxley offered the Modulated Receptor Theory (MRT). MRT The myosin f ilaments, now coupled with the actin suggests that ionic channels are in one of three states: resting, f ilaments, contain quantities of an enzyme called active, or inactive. In the polarized state (phase zero), the ionic ATPase. ATPase, in the presence of magnesium, divides channels (particularly the sodium channels) are resting and the intercellular ATP, by hydrolysis, and releases the nonconducting. When the action potential depolarizes the cell, energy-rich substrate phosphate needed to sustain the then (in sequence) fi rst the sodium (Na), then the potassium contraction. Potassium within the myocardial cell now (K), and then the calcium (Ca) channels open and there- starts a rapid exodus from the cell in an attempt to fore are active.80-82 Once opened, these ionic channels become regain the original resting potential but is unable to do inactive until repolarization occurs and the channel is returned so. Phase 3 thus ends. to a resting state. The recovery of the myocardial cell (repolarization) Antidysrhythmic drugs have their effect during the transi- occurs in phase 4. During phase 4, the sodium-potassium tions between these states of resting: open/active and inactive. pump returns sodium and potassium ions to their original The drugs which act upon the ionic channels during the open/ position, juxtaposed across the cell membrane from each active state will preferentially be attracted to rapidly depolar- other. The cell is again in a state of charged readiness, with a izing ectopic pacemakers. These antidysrhythmic drugs can resting action potential of () 90 millivolts. The cell is now be said to be use- (rate) dependent drugs. Examples of use- ready for another cycle of depolarization–repolarization and dependent drugs include quinidine and procainamide. subsequent myocardial contraction. Drugs that affect the ionic channels in myocardial cells Origins of Dysrhythmia in the inactive state would have an affi nity to slower depo- larizing tissues and would demonstrate a reverse use- (rate) Normally, a clump of tissue in a small region near the open- dependent quality. Reverse use-dependent drugs prolong the ing where the vena cava enters the right atrium, called the repolarization of normal myocardial tissues, as electrographi- sinus-atrial (SA) node, spontaneously depolarizes and thus cally demonstrated by a prolonged QT interval. This slow- initiates the wave of depolarization across the heart. As the ing of repolarization can lead to repolarization disturbances, SA node typically depolarizes earlier than any other tissues, such as Torsades de Pointes (twisting of the points), a form it assumes dominance over the process of depolarization of of polymorphic ventricular tachycardia that can deteriorate the entire myocardium. rapidly into ventricular fi brillation. Spontaneous electrical activity in the SA node results from a loss of resting potential (ionic decay) in the cell wall membrane during diastole. When the ionic decay reaches a threshold, then the cell will spontaneously depolarize. This Street Smart quality, which is exclusive to cardiac cells, is called automa- ticity. However, this automaticity is not solely restricted to the tissues in the SA node. In the past, antidysrhythmic drugs, such as lidocaine, If other myocardial tissues reach the same point of were chosen based upon the provider’s past decay more quickly, and become excitable earlier, then they experience or empiric evidence. Recent research will spontaneously discharge (i.e., self-d epolarization) before the SA node. Typically, pacemaker cells such has cast doubt on the effi cacy of some of these as the ones found in the SA node decay quicker than drugs. Providers are now more likely to choose an other cardiac cells and thus take dominance over the antidysrhythmic drug based on research (an cycle. However, abnormal events at the cellular level (e.g., hypoxia, ischemia, or potassium imbalances) may evidence-based approach) rather than simply upon cause a spontaneous depolarization from an isolated portion past experience. of myocardium, called a focus, which becomes an atypical 656 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Vaughn-Williams Antidysrhythmic Class I Drugs Drug Classifi cations All Vaughn-Williams Class I drugs block the sodium chan- nels in the cell wall membrane, which normally open in All antidysrhythmic drugs affect the action potential of the phase zero. By blocking the sodium channels, Class I drugs myocardial cell by altering ionic infl ux of sodium (Na), decrease the speed of the depolarization (i.e., the conduction potassium (K), and calcium (Ca) into the cell during velocity through the myocardium). In this manner, Class I the depolarization/repolarization cycle (Figure 30-7). drugs decrease chronotropy during the upstroke portion of Using the schema of electrolyte changes along the myo- the action potential of phase zero. cardial cell wall as a foundation for understanding cardiac This therapeutic approach is effective for treating tachy- tissue function, all antidysrhythmic drugs can be divided arrhythmias, particularly those that occur because of reentry according to their effect on a specifi c ion channel in the myo- phenomena. Reentry phenomenon, an error of conduction, is cardial cell membrane. Drugs so grouped can be recognized a common cause of arrhythmia and is the result of impaired for their similar therapeutic effect, even if they have slightly conduction in a portion of the cardiac conduction pathway. different actions. The Vaughn-Williams classifi cation uses Specifi c supraventricular rhythms and ventricular tachycar- this approach, categorizing drugs according to similar elec- dias utilize a reentry pathway mechanism, which creates a trophysiologic actions. circus movement of rapid depolarization and repolarization While the Vaughn-Williams classifi cation system is use- around a block. The result is a tachyarrhythmia. ful in helping to predict a drug’s action, it is not perfect.83 Class I drugs bind to sodium channels which open more Many drugs have effects which cross over to other classes. frequently. This property of Class I drugs, called use- (rate) For example, amiodarone is predominantly a potassium chan- dependence, means that Class I drugs will create a total nel blocker, and thus is grouped with class III drugs. However, blockade at the site of the conduction defect and effectively it also has some other actions which are found in all four terminate the circus movement. Vaughn-Williams classes (Table 30-2). On the downside, the slowed conduction caused by Class I The common characteristic of all antidysrhythmic drugs drugs negatively affects the myocardium’s contractility or is their ability to suppress the excitability (automaticity) of V . (V is a measure of the myocardium’s contractility.) max max the myocardial cell. Suppression of aberrant automaticity, the A loss of contractility directly translates to a loss of force principal source of ectopic pacemakers, results in the elimi- of contraction, or inotropy. Negative inotropy can cause loss nation of the dysrhythmia. Elimination of dysrhythmia may of cardiac output and create hypotension or aggravate heart prevent sudden cardiac death as well as some of the symp- failure. toms associated with dysrhythmia. As a result of slowed conduction velocity, the QRS of the ECG, which is representative of ventricular depolarization, is widened and the QT interval, which represents the total time Street Smart of depolarization to repolarization, is prolonged. Patients with a prolonged QT interval, either as an inborn error of conduction or as a drug-induced complication, who Vaughn-Williams classifi cations (I, II, III, IV) should are given Class I drugs are prone to life-threatening mono- not be confused with the American Heart morphic ventricular tachycardia.84 This is particularly true if Association’s classifi cations (I, IIa, IIb, III) of the the patient also has poor left ventricular function (ejection fraction < 40%) secondary to previous AMI. drug’s effectiveness. Class I drugs are even further divided into Class A, Class B, and Class C according to their similar electrophysiologic effects on the duration of the action potential. Class IA drugs Sodium Sodium Potassium slow phase zero depolarization. Class IB drugs have a lesser channels open channels close channels open effect on

phase zero depolarization, but shorten the repolar- ization time in phase 3. Class IC drugs slowly bind to the Potassium sodium channels, and thus greatly depress the rate of rise in channels close +30 mV the action potential in phase zero. 0 mV Class IA One of the earliest antidysrhythmic drugs was quinidine, a Class -70 mV IA antidysrhythmic. Quinidine attaches to sodium channels as soon as they open during phase zero. Quinidine also creates a Time (ms) 1 ms potassium channel blockade, which increases the duration of the action potential, and in effect, leaves sodium channels open Figure 30-7 Cell depolarization. longer so that more drug can bind with the sodium channels. Pharmacological Interventions for Cardiopulmonary Emergencies 657 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Table 30-2 Actions of Antidysrhythmic Drugs per Vaughn-Williams Classifi cation Effect Effect on V-W Mechanism on Ionic Action Use- Pro- Inotropic Class of Action Channels Potential Examples Dependence Dysrhythmia* dysrhythmia Effect IA Sodium Prolongs Slows Quinidine Reverse use- Atrial fi brillation Torsades Negative channel open/active phase zero Procainamide dependence Ventricular de pointes inotropic effect blocker state depolarization– dysrhythmia Infranodal prolonging block depolarization IB Sodium Prolongs Slows Lidocaine Use- Ventricular Infranodal Negative channel open/active phase zero Phenytoin dependence dysrhythmia block inotropic effect blocker state depolarization Shortens Shortens inactive state phase 3 repolarization – effectively shortening repolarization IC Sodium Prolongs Greatly slows Encainide Use- AV nodal Torsades de channel open/active phase zero dependence re-entry pointes blocker state depolarization WPW-related – little effect on repolarization II Beta-receptor Prolongs Supresses Propanolol Reverse use- Atrial fi brillation AV block Depress left blocker open/active phase 4 Metoprolol dependence WPW ventricular ventricle Calcium state depolarization dysrhythmia function channel blocker III Potassium Prolongs Prolongs Amiodarone Reverse use- Atrial fi brillation Torsades channel inactive state phase 3 Breytlium dependence Ventricular de pointes blocker repolarization dysrhythmia IV Calcium Shortens Shortens Diltiazem Use- AV nodal AV block Negative channel open/active entire action Verapamil dependence re-entry intropic effect blocker and inactive potential Atrial fi brillation states Quinidine may be most noted for its ability to create pro- found hypotension. Dubbed the “Quinidine effect,” Class IA Street Smart drugs all tend to lower blood pressure through massive vasodi- latation created by an alpha-sympathetic blockade. Other Class The effects of Class I drugs on nervous tissues makes IA drugs include procainamide and disopyramide, which both have similar drug effects to a lesser or greater degree. them useful as local anesthetics. Lidocaine and Procainamide saw a great deal of use in the out-of-hospital procaine (the source of procainamide) alter nerve setting for the treatment of ventricular dysrhythmias in the conduction and thus change the patient’s pain 1970s and 1980s. However, it has fallen out of favor as more effective drugs, with fewer side effects, have since become perception. available. Class IB Lidocaine has been extensively used for the treatment Lidocaine is the prototypical drug for Class IB agents. Lidocaine of ischemia-induced ectopy. During periods of ischemia, inhibits fast sodium channels, like Class IA drugs, but does not the speed of ionic exchange in the myocardial tissues is block the potassium channels. The result is a shorter repolariza- impaired. The result is a longer action potential and occa- tion time. Without a prolonged depolarization–repolarization sional spontaneous depolarizations, called after-potentials, cycle, represented by a prolonged QT interval, there is less which can create ventricular ectopy and induce ventricular opportunity for torsades de pointes to occur. fi brillation. 658 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Class IB drugs, such as lidocaine, preferentially block the nervous system in the heart, which could have triggered ear- sodium channels of ischemic tissues, preventing spontaneous lier ectopic beats. depolarizations. Lidocaine has seen a great deal of use in the Administration of Class II agents, such as propra- treatment of ventricular fi brillation during cardiac arrest. nolol, blocks the beta receptors in a lock-and-key fash- 1 Lidocaine is almost immediately metabolized by the liver, ion, decreasing intracellular cAMP, and thereby prevents via fi rst pass biotransformation, and therefore must be continu- unwanted tachycardia. The prevention of tachycardia and ously infused intravenously. Understandably, patients with liver unwanted ectopic beats can be life-saving. dysfunction, such as the elderly, are at greater risk for toxicity. Class II agents can be used to treat hypertension, to prevent angina, as a cardioprotective agent, and to decrease Class IC mortality associated with acute coronary syndrome. Thus, Class IC agents block sodium channels, as do the other Class beta-blockers are a useful drug for the treatment of patients I agents. Class IC drugs also have the added effect of slowing with risk factors for sudden cardiac death. conduction in all cardiac tissues, including the Purkinje fi bers. Use of Class IC drugs, particularly fl ecainide, presents Pharmaceutical Properties a therapeutic quandary. On the one side, Class IC drugs are The fi rst generation of beta-blockers were relatively nonselec- very effective in the treatment of refractory ventricular dys- tive (i.e., blocking both the beta receptors, which dominate 1 rhythmia. On the other side are the results of the Cardiac the heart, as well as the beta receptors, which dominate the 2 Arrhythmia Suppression Trial, which showed a two-fold lungs). Blocking beta receptors can result in bronchoconstric- 2 increase in mortality for patients on the drug.85 Class IC tion. Therefore, use of these drugs required extreme caution in agents are now prescribed for very limited circumstances to patients with asthma or similar reactive airway diseases. patients without a history of myocardial infarction where the The next generation of beta-blockers are more cardiose- benefi ts are thought to outweigh the risk. lective, meaning they primarily affect the heart and have a lesser impact on the lungs. Thus, they are safer to use. The Class II Drugs newest, third generation of beta-blockers have additional vasodilatory properties which can be helpful in reducing the Class II agents block the sympathetic nervous system’s stim- work of the heart. ulation of beta receptors in the heart. At fi rst glance, inclu- sion of beta-blockers in the Vaughn-Williams schema would Antihypertensive Properties appear inconsistent with the other classes of antidysrhythmic drugs. Other antidysrhythmic drugs in the Vaughn-Williams Beta-blockers exert a powerful antihypertensive effect by classifi cation depend on blocking electrolyte channels in the blocking the alpha-adrenergic receptors in the peripheral cell wall membrane. Beta-blockers also block electrolyte blood vessels, leading to vasodilation and a reduction in channels. Beta-blockers work indirectly on electrolyte chan- peripheral vascular resistance. This is measured crudely by nels in the cell wall membrane by inhibiting the chemical the diastolic blood pressure. messenger, which opens calcium channels. The heart has abundant beta receptors; about 85% of the 1 sympathetic receptors within the heart are of the beta type. Street Smart 1 The direct effect of stimulating a beta adrenergic receptor is 1 to cause a series of messenger proteins, such as cyclic AMP, Sudden withdrawal from beta-blocker medication, to stimulate calcium channel opening. Increased calcium in a consequence of unpleasant side effects in many the myocardium increases the strength of contraction (a posi- tive inotropic effect) and thereby improves cardiac output. cases, can lead to rebound hypertension. Unchecked, Open calcium channels also have a number of other asso- the hypertension can increase to the level of a ciated electrophysiologic effects. These include increased hypertensive crisis during which damage to the eyes, automaticity of the SA node with accelerated conduction brain, heart, and kidneys can occur. through the AV node, resulting in the customary tachycardia which accompanies administration of adrenergic agonists. An increase in spontaneous depolarization of ischemic tissue can be seen as well. Antidysrhythmic Properties A blockade of the beta-adrenergic receptors in the myo- Beta-blockers are effective antidysrhythmic agents. These cardium prevents calcium channels from opening by decreas- medications are most effective for dysrhythmias caused ing the level of cellular cAMP available to open the calcium by errors of automaticity (i.e., abnormal automaticity) or channels.86–88 With fewer calcium channels open, the result errors of conduction (e.g., Wolff-Parkinson-White syndrome is an inhibition of spontaneous depolarization during phase (WPW) or Lown-Ganong-Levine (LGL)). Untreated, these 4. In short, beta-blockers prevent fi ring of ectopic myocar- errors in rhythm can lead to hypotension, syncope, and sud- dial cells by blocking the beta receptors of the sympathetic 1 den cardiac death. Pharmacological Interventions for Cardiopulmonary Emergencies 659 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Beta-blockers indirectly preclude the myocardium from Normal creating errors of impulse generation by preventing sympa- thetically induced tachycardia. These tachycardias can create a mismatch between the work of the heart and the coronary arteries’ ability to supply oxygen-rich blood to the myocar- dium so the heart can do its work. This mismatch can result in myocardial cell hypoxia, which in turn leads to abnormal depolarization and the formation of ectopic pacemakers. Extra-cardiac causes of excessive tachycardia include pheochromocytoma, an epinephrine-excreting adrenal tumor, and a thyroid storm (thyrotoxicosis), to name just a few. Regardless of the etiology, beta-blockers prevent tachycardia, which can lead to ventricular irritability. Beta-blockers can also effectively treat errors of impulse conduction. Errors of impulse conduction are created by either a unidirectional block in the conduction pathway or the presence of an additional accessory pathway (seen in WPW). These errors in conduction create an abnormal conduction mechanism called reentry phenomenon. Under normal conditions, the impulse from the SA node Accessory pathway creates an action potential that fl ows down the conduction system to the base of the bundle branches where the conduc- tion bifurcates into two branches. It is then transmitted across the ventricular myocardium in a wave. If a segment of the pathway experiences hypoxia and ischemia, or has already been depolarized by an accessory pathway which electrically connects the atrium and the ven- tricle, then the cells will be unresponsive to stimulation, in effect creating a block. However, when the depolarization wave comes back around to the block from the opposite direction, it can pass this time, in effect making the block unidirectional. Both normal conduction and abnormal con- duction are created by ischemia and an accessory pathway (Figure 30-8). The myocardial cells beyond the block now have had time to recover and can be depolarized, albeit in retrograde fashion. Since the conduction path is now altered, the action potential will continue to depolarize tissue by following a Figure 30-8 Normal conduction and abnormal reverse pathway. The consequence can be either localized conduction created an accessory pathway. depolarization and the creation of an ectopic pacemaker, or creation of a circular conduction depolarization (called a cir- cus movement) that can lead to ventricular tachycardia and This impressive list of cardioprotective effects is owed in supraventricular tachycardia. large part to the negative chronotropic effect of beta-blockers. The impact of beta-blockers on this type of dysrhythmia By decreasing heart rate (negative chronotropy), beta- is to slow conduction so that the SA node can retake domi- blockers create increased diastolic time. The diastolic time nance. Beta-blockers do not affect either oxygenation of the is that period in the cardiac cycle when the coronary arter- heart or block accessory pathways such as the one seen in ies fi ll. Increased coronary artery fi lling directly translates to WPW. improved myocardial perfusion. As an added bonus, beta-blockers also dilate

the periph- eral blood vessels, creating a reduction in the resistance Acute Myocardial Infarction against which the heart must pump (afterload) and the total Early administration of beta-blockers during an acute myo- work of the heart. cardial infarction can reduce the size of infarction, decrease Early administration of beta-blockers, within the fi rst the risk of re-infarction, prevent cardiac rupture, preclude four hours of onset of the suspected myocardial infarction, episodes of ventricular tachycardia and supraventricular holds the greatest promise for decreasing mortality (accord- tachycardia, and prevent sudden cardiac death.89–93 ing to one study, a decrease by 15% in the fi rst week).63 660 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. When administered within the fi rst four hours, infarc- Table 30-3 American Heart Association and tion size can be reduced by as much as 30% and the risk of American College of Cardiology Guidelines for the re-infarction of reperfused myocardium strikingly reduced. Management of Patients with Acute Myocardial Those patients who received beta-blockers within the fi rst Infarction—Use of Beta-Blockers two hours of symptom onset had a 61% reduction in six- week mortality in another study.94 Class 1 These fi ndings lend support to the concept that beta- 1. Acute myocardial infarction blockers should be administered as early as possible. a. Within 12 hours of onset of infarction Some Paramedics routinely administer beta-blockers when b. Without contraindication to beta-blocker therapy for example confronted with a patient who is suspected of having an i. Active heart failure acute myocardial infarction as evidenced by history and ii. Asthma/COPD 12-lead ECG. iii. bradycardia c. Non ST-segment elevation (Confi rmed by enzyme tests) Electrical Storm 2. Recurrent chest pain Patients with a recent myocardial infarction can be prone a. Unstable angina to multiple recurrent episodes of ventricular fi brillation 3. Tachyarrhythmia (V. Fib.) called an electrical storm. Treating patients with a. Atrial fi brillation with a rapid ventricular response electrical storm conventionally (with standard Advanced Cardiac Life Support [ACLS]) has produced uniformly poor outcomes. A trial of patients with electrical storm, for whom beta- Contraindications blockers were used after successful conversion of ventricu- Beta-blockers should be administered cautiously in patients lar fi brillation, has shown promise. A remarkable increase in who are diabetics prone to hypoglycemia, have unstable survival in the study group was shown (5% with traditional asthma, or have chronic obstructive pulmonary disease, for ACLS versus 67% with a beta-blocker).95 the reasons that were previously described. Beta-blockers have to be administered cautiously, if at Heart Failure all, in cases of cocaine-induced tachycardia, with or without Traditionally, healthcare providers avoided the use of beta- chest pain.97–99 Cocaine prevents the re-uptake of the neu- blockers in the treatment of heart failure patients, fearing that rotransmitter epinephrine, creating an overload of epineph- the hypotension sometimes created by beta-blockers would rine in the synaptic junction. By blocking the beta-adrenergic aggravate the already failing heart. receptors only, cocaine’s effect on alpha-adrenergic receptors In a recent international study which enrolled over is unimpeded and profound hypertension from peripheral 4,000 patients, beta-blockers have shown new promise in vasoconstriction can occur. treating chronic heart failure. Patients with heart failure sub- Toxicity sequent to acute myocardial infarction who are treated with carefully titrated beta-blockers evidence a slower progression Beta-blocker toxicity can be absolute, as in the case of an in heart failure and an overall 35% decrease in mortality.96 overdose, or relative, as in the case of a patient with a pre- However, beta-blockers are still considered potentially existing heart block that results in a worsening of the heart harmful (Class III) in acute pulmonary edema and should not block. The immediate impact of beta-blocker toxicity is a be used in the fi eld unless under direct orders of a medical profound bradycardia with all of its attendant complications. control physician.77 In many cases, the administration of atropine, a parasympa- thetic blocker, is effective in restoring a tolerable heart rate. In cases where atropine is ineffective, such as in a ven- Therapeutic Keystone tricular bradycardia secondary to complete heart block, then The benefi ts of decreased heart rate and blood pressure transcutaneous external pacing may be used. To mitigate the (which in turn decreases myocardial oxygen demand) and the discomfort created by external pacing, many providers pre- advantage of enhanced coronary artery blood fl ow produced medicate the patient with an analgesic. by a beta-blockade combine to improve myocardial perfusion Frequently, hypotension is a complication of bradycar- and decrease associated mortality and morbidity. dia. Added hypotension created by analgesics would only For these reasons, the American Heart Association and compound the situation. In those cases, glucagon may be the American College of Cardiology have made administra- administered. Glucagon bypasses the beta-adrenergic recep- tion of beta-blockers in acute myocardial infarction a Class I tors and stimulates the formation of cyclic AMP (cAMP) intervention, which is defi ned as conditions for which there is directly. This in turn increases the intercellular calcium, evidence and/or general agreement that a given procedure or creates stronger contractions, and improves conduction, treatment is benefi cial, useful, and effective (Table 30-3). particularly within the calcium-sensitive AV node. Pharmacological Interventions for Cardiopulmonary Emergencies 661 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. In extreme cases, when none of the aforementioned treat- QT produced by Class III drugs can precipitate torsades ments are effective or they are contraindicated, then high- de pointes.100,101 This complication of treatment is more dose dobutamine can be used to overcome the competitive common in patients with low blood potassium, possibly blockade. secondary to use of a potassium-wasting diuretic like furosemide. Torsades, as it is more commonly referred to, appears similar to ventricular tachycardia on the ECG. This similarity can lead to disastrous consequences as Street Smart ventricular tachycardia erroneously treated with Class III drugs can further worsen the patient’s condition. Beta-blockers prevent the refl exive tachycardia Indications that follows a loss in blood pressure. Paramedics Class III drugs can be thought of as “wide-spectrum” anti- often depend on monitoring a mounting tachycardia dysrhythmics, effective in treating both atrial and ventricular to evaluate for hemodynamic decompensation. dysrhythmia. Amiodarone, for example, prolongs the refrac- Beta-blockers prevent the tachycardia and thus tory period of all cardiac conductive tissues and therefore is mask the impending hypotension associated effective in treating atrial fi brillation, atrial fl utter, and WPW, as well as ventricular tachydysrhythmia.102 with decompensated shock. With the loss of this Amiodarone does not exhibit the reverse use-dependence compensatory mechanism, patients on beta-blockers that is common with other drugs in this class. Amiodarone are also more prone to orthostatic hypotension. also exhibits some Class I and II qualities as well, making its exact mechanism of action more diffi cult to establish. However, its predominant effect is on the duration of the Class III Drugs action potential. Amiodarone has received a great deal of attention for When the sodium channels are all open, at the end of phase its reported effectiveness during ventricular fi brillation or zero, the cell is incapable of being further stimulated and is ventricular tachycardia. The ARREST study (Amiodarone said to be refractory to stimulation. This period of time cor- in the Out-of-Hospital Resuscitation of Refractory responds with the fi rst one-half of the T wave of an ECG. Sustained Ventricular Tachyarrhythmias), published in the The exodus of potassium from the cell marks the start New England Journal of Medicine, seemed to demonstrate of the repolarization, or phase 1 of the action potential. The that patients receiving amiodarone during cardiac arrest are speed of repolarization is a function of local conditions at the more likely to survive until arrival at the hospital. However, cellular level (acidity, hypoxia, etc.) as well as the order of the study did not have the statistical power to detect differ- depolarization. Therefore, each cell repolarizes at a slightly ences in survival to discharge from the hospital.103 different rate. Based on the power of this study, the American Heart Some repolarized myocardial cells are vulnerable to Association (AHA) has given amiodarone a Class IIb rec- reactivation. Thus, the myocardial tissue is said to be rela- ommendation (possibly helpful) in its Advanced Cardiac Life tively refractory (the second one-half of the T wave). A strong Support (ACLS) guidelines. stimulus (e.g., from a late depolarizing ectopic focus) can The ALIVE trial (Amiodarone vs Lidocaine in Prehospital initiate a premature second action potential during this vul- Refractory Ventricular Fibrillation Evaluation) seems to nerable period. The result can be a chaotic depolarization of indicate the superiority of amiodarone over lidocaine in the myocardial cells (recorded as ventricular fi brillation on the treatment of out-of-hospital cardiac arrest due to ventricular ECG) or creation of a unidirectional block, setting the stage fi brillation or ventricular tachycardia.104 for a circus movement. Class III drugs prolong the absolute refractory time of myocardial tissues by blocking the potassium channels and Class IV Drugs decrease the incidence of early depolarizations. Class III Free calcium, released from within the cells via calcium drugs are also taken up more quickly by normal cells than by channels during depolarization, binds with troponin and ini- ischemic cells, demonstrating a reverse use-dependence. As a tiates muscular contraction (excitation-contraction coupling). result of a prolonged refractory period of normal myocardial There are two types of calcium channels in myocardial and cells secondary to reverse use-dependence, slower ischemic smooth muscle: L-type (long-lasting) and T-type (transient). myocardial cells can depolarize without danger of initiating a L-type calcium channels are more abundant in the heart and second ectopic action potential. calcium channel blockers predominantly affect L-type cal- The effect of Class III drugs upon the action poten- cium channels. tial can be observed by the lengthened QT interval on the The different effects of calcium channel blockers upon the ECG, the visible demonstration of the depolarization– heart are owed to the various types of tissues within the heart repolarization time. In a small population, the prolonged and give rise to the therapeutic benefi ts of calcium channel 662 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. blockers during coronary artery syndrome. Calcium chan- nel blockers are also effective antihypertensive agents. These Street Smart drugs inhibit the contraction of the smooth muscle found within the middle layer, the tunica media, of blood vessels. The result is widespread vasodilation in the peripheral cir- Digitalis toxicity can lead to bizarre derangements culation. Peripheral vasodilation reduces peripheral vascular of conduction, including the creation of atrial resistance, crudely measured as diastolic pressure, and lowers tachycardias along with intermittent AV blocks. The the blood pressure. This reduction in afterload decreases the unsuspecting provider who administers a calcium work of the heart as well. As a group, calcium channel block- ers are well-tolerated and have fewer side effects than other channel blocker to a digitalis toxic patient may see antihypertensive agents, such as beta-blockers. the creation of a lethal AV block. Calcium channel blockers are also effective anti-anginal agents. The pain of the ischemic heart (i.e., angina) is the result of a mismatch between blood supply (usually from Precautions compromised coronary arteries) and demand (from an over- taxed heart). The combination of peripheral vasodilation The fi rst generation of calcium channel blockers, starting (reduced

afterload, which in turn reduces the work of the with verapamil (which was developed in Europe in 1963), heart) and local coronary artery vasodilation re-establishes frequently created profound hypotension, secondary to the balance between myocardial supply and demand and widespread vasodilation. Second generation calcium chan- eliminates angina. nel blockers, including diltiazem (which was developed in Perhaps the most important use of calcium channel Japan), are less likely to create hypotension and are therefore blockers is as an antidysrhythmic drug which decreases auto- preferred for prehospital use during an emergency. maticity. The effect of calcium on the cardiac conduction is If life-threatening hypotension does occur, co- dissimilar to the effect of calcium upon muscle. In the muscle, administration of calcium gluconate can provide free calcium calcium combines with troponin to create a contraction. In for improved muscle contraction and a return toward a nor- the cardiac conduction, calcium is part of the depolarization– mal blood pressure. Similarly, profound bradycardia can be repolarization cycle. Specifi cally, depolarization is generated treated with the parasympathetic blocker atropine to restore by the inward fl ow of calcium during phase zero. a normal heart rate. Portions of the cardiac conduction system that are espe- cially sensitive to increased calcium are the SA node (result- Unclassifi ed Antidysrhythmic Agents ing in increased automaticity) and the AV node (resulting in There are a certain number of antidysrhythmic agents which increased conduction). do not fall cleanly into one of the Vaughn-Williams classifi - Calcium channel blockers decrease the automaticity of cations and are therefore presented separately. For example, the SA node, resulting in a slower heart rate (negative chro- adenosine, a naturally occurring purine nucleoside, does not notropic effect). Calcium channel blockers also decrease the fi t into the Vaughn-Williams classifi cation system, yet is used conductivity across the AV node, resulting in slower con- to treat certain tachydysrhythmias. duction in the AV node (negative dromotropic effect). The Adenosine affects the nervous system of the heart, yet combination of a slower heart rate and slowed conduction to it is not a neurotransmitter nor is it a hormone. Adenosine the ventricles creates an overall reduction in the number of is a neuromodulator. A neuromodulator is a substance contractions. These effects make class IV agents, the calcium that adjusts, or modulates, the rate of a neuron’s discharge. channel blockers, the preferred antidysrhythmic agents for Adenosine’s effect is to either increase or decrease cyclic specifi c dysrhythmias such as supraventricular tachycardia. AMP levels, which in turn adjusts calcium levels and infl u- ences the strength of contraction. Adenosine may serve a special protective function Contraindications in ischemic heart tissue. In normal heart tissue, adenosine Calcium channel blockers are particularly effective in the stimulates purine receptors (which in turn reduce the inward calcium-sensitive AV node. However, any calcium chan- fl ow of calcium) and increases the outward fl ow of potas- nel blocker can worsen a pre-existing AV heart block and sium during phase 4 (repolarization) of nervous tissue. It thus therefore should be given with extreme caution to patients increases the strength of contraction of heart muscle. with pre-existing AV nodal disease or sick sinus syndrome. During periods of tissue hypoxia, ischemic cells release Calcium channel blockers can also interact with beta- cyclic AMP (cAMP) into the interstitial space in the form blockers to create extreme bradycardias. of adenosine. Free serum adenosine then enters the coro- Digitalis, a medication prescribed for heart failure, nary blood vessels and blocks adrenergic receptors as well has a similar inhibitory effect upon the AV node. The combi- as stimulating the release of nitric oxide (NO), the vasodi- nation of a calcium channel blocker and digitalis can create lator thought to be at work in nitroglycerin. This combina- profound bradycardia and subsequent syncope. tion of effects creates vasodilatation and increased coronary Pharmacological Interventions for Cardiopulmonary Emergencies 663 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. circulation. However, this vasodilatation is not limited to the uptake also has implications for intravenous administration. heart. When adenosine is given intravenously, it produces a In order for therapeutic levels to be achieved in the heart (the generalized fl ush and produces hypotension in about 20% of target organ in most cases), adenosine must be given as a the patient population. rapid bolus via the shortest route to the heart. Adenosine also acts to inhibit the effects of epinephrine Xanthine, a prodrug of respiratory medication aminophyl- on the SA node (negative chronotropic effect) and gener- line, causes bronchodilation by blocking adenosine receptors. ally slows the conduction (negative dromotropic effect). It is Foods that commonly contain xanthine compounds include this action which makes adenosine useful as an antidysrhyth- teas and coffee. Higher than normal doses of adenosine may mic agent. be needed to overcome the competitive blockade produced by Adenosine’s inhibition of norepinephrine release is so the xanthine compounds. overwhelming that often, following rapid intravenous admin- Conversely, adenosine should be administered cautiously istration, the heart is rendered momentarily asystolic. The to patients with reactive airway diseases, such as asthma, for therapeutic goal of adenosine administration in those cases is fear of precipitating a life-threatening bronchospasm. to stun the entire myocardium so as to permit the SA node to recommence its role as the dominant pacemaker. Vasopressin Adenosine is particularly effective in treating aberrant Vasopressin, or antidiuretic hormone (ADH), is a naturally conduction over accessory conductive pathways (e.g., the occurring peptide created in the posterior lobe of the pituitary bypass tracts in WPW and LGL) or in preventing a unidirec- gland. Vasopressin was known to have potent vasoconstrict- tional block. Unidirectional blocks can, under the right cir- ing properties at higher doses and has been used to treat dia- cumstances, create a circus movement within the conduction betes insipidus and bleeding esophageal varices, with varying tract and cause an extreme rate supraventricular tachycardia. degrees of success, in the past. However, vasopressin was pri- marily regarded as a hormone for maintaining water balance Indications in the kidney. Researchers were surprised to fi nd elevated Adenosine is used to treat supraventricular tachycardias asso- levels of vasopressin in survivors of cardiac arrest.105 Upon ciated with WPW or LGL syndromes as well as a number closer examination, medical researchers felt that vasopressin of other narrow-complex tachycardias. Adenosine is ineffec- might have some theoretical advantages over epinephrine in tive in treating the rapid ventricular response associated with cardiac arrest. atrial fi brillation or atrial fl utter; errors of automaticity. These Epinephrine is traditionally considered the drug of conditions involve ectopic pacemakers outside of the normal choice in cardiac arrest because it increases the strength of conductive system and thus are less affected by adenosine. contraction, or in the case of ventricular fi brillation, it coars- ens the fi brillation and thereby improves the chance of suc- cess with defi brillation. Epinephrine also raises peripheral vascular resistance, thereby increasing backfl ow into the Street Smart coronary arteries and improving cerebral circulation. On the other hand epinephrine, particularly high-dose epinephrine, A wide-complex tachycardia of unknown origin can increases the oxygen demand—as well as the demand for present a diagnostic dilemma. The dysrhythmia could ATP—at a time when the heart is depleted.106 Epinephrine also appears to adversely affect pulmonary function during be a potentially lethal ventricular tachycardia or it cardiac arrest, by shunting blood away from the lungs to the could be an atrial fi brillation in a patient with WPW. heart and brain.105 Inappropriate treatment can produce less than desired In fact, currently no research exists which suggests effects. As adenosine is not an effective treatment that epinephrine administration increases survival. Several uncontrolled studies indicate that epinephrine administration for ventricular tachycardia, its administration can during cardiac arrest negatively correlates with survival to serve as a diagnostic tool for differentiating the discharge.107 However, until better studies are available, epi- two rhythms and help guide subsequent therapeutic nephrine remains in the standard guidelines for management interventions. of cardiac arrest.108 Vasopressin increases vascular tone and perfusion pres- sures, like epinephrine, but does not have the associated neg- ative catecholamine-induced effects of increased heart rate Precautions and oxygen consumption which are seen with epinephrine. Adenosine, as a naturally occurring nucleoside, is rapidly Vasopressin has a relatively long half-life and therefore taken up by red blood cells and vascular endothelial cells, need only be administered once in order to achieve thera- where it is metabolized into inosine and then uric acid. This peutic levels. Early research fi ndings seem to indicate metabolism occurs so rapidly (the half-life of adenosine is 5 better patient survival when vasopressin is administered to 10 seconds) that toxicity is nearly impossible. This rapid along with epinephrine every three to fi ve minutes.109 664 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. A large out-of-hospital clinical trial is needed before it can or an obstruction in the outfl ow from the heart due to valve be defi nitively stated that vasopressin is of greater benefi t disease. than epinephrine in cardiac arrest. Diastolic heart failure is that condition in which the heart has diffi culty fi lling properly and there is subsequent loss Cholinergic Blocking Agents of cardiac output. Causes of diastolic heart failure include Cholinergic blocking agents, as a class, were discussed ear- remodeling of the ventricular chamber secondary to chronic lier. However, atropine, a specifi c parasympathetic blocking hypertension, obesity, and systolic heart failure. agent commonly used to treat symptomatic bradycardia, is The pathophysiology of heart failure begins with a loss now revisited. of cardiac output, from whatever cause, which stimulates the Atropine blocks the parasympathetic neurotransmitter baroreceptors. The baroreceptors in turn increase sympathetic acetylcholine at the muscarinic receptors. This effectively discharge (epinephrine) to adjust for the volume difference diminishes the infl uence of the primary parasympathetic and maintain perfusion of vital organs. nerve, the vagus nerve (vagal tone), and permits the sym- Sympathetic stimulation has a two-fold impact. First, pathetic nervous system to re-establish dominance over the stimulation of alpha-adrenergic receptors preferentially heart’s rate. Excessive vagal tone is often seen in cases of AV vasoconstricts peripheral vascular beds, effectively shunt- node ischemia secondary to occlusion of the right coronary ing blood to core organs, as well as increasing the amount of artery, as occurs during an inferior wall myocardial infarc- blood returned to the heart (preload). With the ventricles now tion. The ensuing bradycardia can be treated effectively with “overfi lled,” Starling’s law dictates that the ventricle will con- atropine. However, increasing tissue demands within the AV tract more forcefully and the stroke volume will increase.112 node at a time when the tissues are ischemic may accelerate Sympathetic stimulation also increases the heart rate damage and lead to an infarction of the AV node, resulting in (positive chronotropic effect) as well as strength of contrac- complete heart block. The decision to use atropine in the set- tion (positive inotropic effect). ting of an AMI must be made with caution. The combination of increased stroke volume and increased heart rate should result in improved cardiac out- put (SV x HR  CO). This is the body’s normal response to hypovolemia. The diffi culty lies not in the blood’s volume but Street Smart in the heart’s inability to pump that volume. Alpha-adrenergic stimulation from epinephrine excreted Profound hypoxia produces pupillary dilation. secondary to hypotension increases the systemic vascular During a cardiac arrest, providers often check resistance (the afterload) against which the heart must pump. This “afterload mismatch” causes blood to back up into the pupillary response to assess the effectiveness of pulmonary circuit, resulting in pulmonary congestion and cardiopulmonary resuscitation. Atropine dilates edema.

Elevated pressure is transmitted across the pulmonary pupils, thus rendering this sign inaccurate. circuit and through the right ventricle back into the systemic circulation, creating peripheral edema. The kidneys, now underperfused, activate the renin- Heart Failure angiotensin-aldosterone mechanism, a tri-axis of hormones which combine to preserve blood volume. This results in Heart failure is the heart’s inability to pump enough blood to more fl uid retention, further increasing the work of the over- meet the body’s demands. The result is hypoperfusion of vital taxed heart. organs and potentially the onset of a shock syndrome. Heart In an effort to compensate, the heart dilates to accept failure affects over 4 million people in the United States and more blood and the muscle fi bers thicken, a process called is the most common hospital discharge diagnosis in patients hypertrophy, in order to pump more forcefully. Along with over the age of 65.110,111 a sustained tachycardia secondary to persistent sympathetic Heart failure can be divided into two categories: systolic stimulation, the heart is able to compensate, sometimes for heart failure and diastolic heart failure. Systolic heart fail- years. ure is the condition in which the heart cannot pump adequate The dual effect of dilation and hypertrophy upon the left amounts of blood into the circulation. The result can either ventricle slowly changes the shape of the interior chamber, be forward failure (a loss of cardiac output and systolic called remodeling, into a less effective confi guration. The blood pressure) or backward failure (a retrograde buildup of remodeled chamber can no longer fi ll properly and diastolic pressure that is transmitted to the low pressure lung fi elds heart failure ensues. and creates pulmonary congestion and pulmonary edema). When the heart reaches the point where it can no lon- Frequently, this left-sided heart failure progresses through the ger compensate and overcome the increasing demands put right ventricle and into the systemic venous circulation. upon it, the heart enters the descending limb of the Frank- Causes of systolic heart failure include loss of con- Starling curve and cardiac output falls. In 1918, Frank tractile strength secondary to acute myocardial infarction and Starling advanced the idea that the force of the heart’s Pharmacological Interventions for Cardiopulmonary Emergencies 665 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. contraction is proportional to the length of the muscle fi bers, mechanism (Figure 30-9). This is an effective treatment for which are increased with increased ventricular fi lling. When hypertension in many patients. the myocardial fi bers can no longer stretch, then the muscle ACE inhibitors are seeing greater use in heart loses contractile strength (the backside of the curve). The failure patients as they appear to not only interrupt the pharmaceutical goals in heart failure are essentially two- renin- angiotensin-aldosterone mechanism, thereby prevent- fold: reduce the preload and provide inotropic support to the ing fl uid retention, but they also control hypertension and failing heart. thus reduce the work of the heart. They are also effective in reversing left ventricular systolic dysfunction. Long-term use Angiotensin-Converting Enzyme of ACE inhibitors have been shown to improve survival of (ACE) Inhibitors even severe heart failure patients by returning the heart to Baroreceptors in the kidneys, sensing a low fl ow state due to its original condition.113 reduced arterial pressure caused by heart failure, release the Therapeutic Approaches enzyme renin. Renin is converted into angiotensin through a number of steps. to Heart Failure Angiotensin has a number of physiologic effects. Hippocrates advanced the idea that the four humors, including Angiotensin stimulates the production of aldosterone in the blood, had to be in balance in order to maintain good health. adrenal cortex. Aldosterone, a mineralocorticoid, promotes When the body was swollen (e.g., from heart failure), then it the excretion of potassium by the kidney in exchange for was thought that blood had to be released from the body to retaining sodium and thus water. Angiotensin also stimulates restore balance. For centuries, fi rst monks, and then barber- the secretion of vasopressin, which in turn causes peripheral surgeons, continued the practice of bloodletting to relieve vasoconstriction and increased peripheral vascular resis- “dropsy,” the term used for heart failure. Leeches replaced the tance. Perhaps most importantly, angiotensin is a potent lancet in the 1800s, but the practice continued. In fact, the word v asoconstrictor in itself. It is 40 times more potent than “leech” comes from the Old English “laece” which means phy- norepinephrine in causing peripheral vasoconstriction. sician.114 Even George Washington was bled by Dr. Benjamin The conversion of renin into angiotensin depends on an Rush. Washington’s leeching is thought to have been a contrib- enzyme called angiotensin-converting enzyme (ACE). ACE uting cause to his death. While this treatment may appear to be inhibitors, such as captopril, oppose the conversion of renin to barbaric by today’s standards, it nevertheless was effective for angiotensin and thus upset the renin-angiotensin-aldosterone treating heart failure in some instances. Response mediated by the sympathetic nervous system Activation of β1 adrenoceptors Cardiac on heart output Sympathetic activity Activation of α1 adrenoceptors Peripheral on smooth muscle resistance Decrease in Increase in blood pressure blood pressure Renal blood Renin Angiotensin II flow Aldosterone Glomerular Sodium, water filtration rate Blood volume retention Response mediated by the renin-angiotensin-aldosterone system Figure 30-9 Afterload mismatch. 666 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. As primitive as these early interventions may have The reabsorption of water and salts occurs in various por- seemed, subsequent pharmaceutical approaches to heart fail- tions of the nephron. Approximately 65% of the water—as ure have used the same tactic—reduce the volume of blood in well as bicarbonate, glucose, and two-thirds of the sodium—is order to decrease the work of the heart and allow the heart to reabsorbed in the proximal tubule (Figure 30-10). function more effi ciently. The proximal tubule is also the site of absorption of The reduction of blood can occur in two ways: either organic acids, such as uric acid, and metabolites of medica- removal of fl uid from the circulation via the kidney (diuresis) tions. The remaining fi ltrate passes into the loop of Henle. The or relocation of fl uid into other compartments (vasodilation). cells lining the narrow ascending loop of Henle are extraordi- nary because they are watertight (i.e., impermeable to water). This section of the nephron actively reabsorbs chloride and Diuresis sodium. To this point the exchange has been unregulated. Approximately 20% of the blood entering the kidney’s The remaining 15% of fi ltrate which remains now enters glomerular process diffuses its water and solutes (salts the distal convoluted tubule. The regulation of potassium and in solution) into the Bowman’s capsule of the kidney’s sodium reabsorption in this portion of the nephron is con- nephron. Only the formed elements, such as red blood cells trolled by aldosterone. and plasma proteins, are held back. The water and plasma The remaining fi ltrate, now called urine, is passed into solutes, now called fi ltrate, pass through the different por- the collecting duct. Vasopressin, or antidiuretic hormone tions of the nephron and are reabsorbed to go back into the (ADH), regulates the fi nal reabsorption of water in this por- circulation. In an average day the kidney will fi lter 180 liters tion of the nephron. The process of renal fi ltration is complete of blood but only produce one to two liters of urine. with 99.2% of the fi ltrate returned to the central circulation Blood vessel Part of a nephron Tubular filtration — Afferent water, glucose, amino acids, salts, High arteriole and urea pass through the glomerulus. blood pressure Urinary Kidney tubule force Filtration filtrate A glomerulus Lining cells (set of capillary of kidney tubules loops) Efferent arteriole Tubular reabsorption includes water, glucose, amino acids, vitamins, bicarbonates, CA+, Mg+, N2+, and Cl- Tubular secretion includes ammonia, creatinin, hydrogen, potassium, and some drugs Urinary meatus Excreted urine Urination (micturition) Figure 30-10 Cross-section of nephron. Pharmacological Interventions for Cardiopulmonary Emergencies 667 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. and the remainder, the urine, being sent to the bladder via the Bumetanide, another loop diuretic, also blocks the reab- ureters to be excreted. sorption of chloride in the proximal tubule. This dual effect makes bumetanide more potent than furosemide. This second Diuretic Agents site of action makes bumetanide effective for patients who are resistant to furosemide. The creation of urine is controlled by the pressure of the blood entering the kidney, which in turn is controlled (in part) by the sympathetic nervous system, and the concentration of the salts Precautions in the blood, as well as the ADH level. Patients without prior experience with diuretics may unpre- Each class of diuretics affects a different portion of the dictably experience a diuresis of large quantities of urine. The kidney’s nephron and therefore has a slightly different effect result can be severe hypovolemia, hypoperfusion, and frank on diuresis. Carbonic anhydrase inhibitors affect water reab- shock. In those cases, gentle rehydration with intravenous sorption in the proximal convoluted tubule, whereas the loop solutions, such as Ringer’s lactate, can re-establish lost vol- diuretics and the thiazides affect the loop of Henle. Finally, ume and restore the blood pressure. the potassium-sparing diuretics affect the distal convoluted Overly aggressive treatment of congestive heart failure, tubule. usually manifested by pulmonary edema, can also lead to Regardless of the affected portion of the nephron, all even greater problems in the care of the patient over the long medications which cause the increased loss of fl uid and salts term. When confronted with a patient with pulmonary edema, from the body are called diuretics. This loss of fl uid volume Paramedics may be inclined to think that the patient is fl uid decreases the amount of circulating blood volume and ulti- overloaded. More accurately, these patients are fl uid mis- mately decreases the work of the heart. Therefore, the uni- placed. That is, the blood is being sequestered in the venous versal goal of diuretic therapy is to reduce the work of the circulation (venous pool) and is putting pressure on the fail- heart and permit the heart to function more effi ciently. ing heart to pump it forward. There are two treatment path- Proximal Tubule Diuretics ways to relieve this condition. First, the Paramedic can cause a diuresis which will in turn reduce the blood volume return- The enzyme carbonic anhydrase mediates the acid and bicar- ing to the heart. Alternatively, the Paramedic can increase the bonate reaction that creates water and carbon dioxide (H venous pool’s capacitance, temporarily relieving the heart’s HCO  H O  CO ) in the blood. In the sodium bicar- 3 2 2 burden and allowing it to recover. bonate and acid reaction, carbonic anhydrase inhibitors hold The classic diuretic for the treatment of acute pulmo- onto a hydrogen ion in exchange for a sodium ion that is sub- nary edema has been furosemide. Prompt treatment with sequently secreted by the kidneys. As a matter of principle, furosemide will provide the patient with immediate relief of water follows salt, and water is also excreted. symptoms.117,118 This relief is due to the two-fold action of Carbonic anhydrase inhibitors include acetazolamide furosemide. Furosemide’s

immediate effect is as a vasodila- (a sulfonamide without antibacterial properties). In com- tor. Within fi ve minutes of administration, furosemide reduces parison to loop diuretics, carbonic anhydrase inhibitors the heart’s work by reducing the preload through vasodila- are a weak class of diuretics which are used in very lim- tion, increasing the venous pool capacitance. Following the ited cases. For example, mountain climbers who hike above vasodilatation, within 20 minutes of the onset of action furo- 10,000 feet are prone to high-altitude pulmonary edema semide causes diuresis. This diuresis removes fl uid from the (HAPE) and high-altitude cerebral edema (HACE).115,116 central circulation and reduces the heart’s work. Acetazolamide is sometimes prescribed to climbers to Patients in acute heart failure are not suffering from prevent HACE and HAPE. The exact mechanism of being fl uid-overloaded. More correctly, the blood volume action is unknown but is thought to be associated with is improperly distributed, leading to an input–output mis- the mild metabolic acidosis created by the drug and the match. Vasodilator therapy may be more benefi cial to the resulting deeper respirations which occur during the moun- patient in the long run. More discussion about vasodilator taineer’s sleep. therapy follows. Potassium, an important cardiac electrolyte, is closely Loop Diuretics associated with sodium. As loop diuretics cause the excre- Loop diuretics, as a class, inhibit the reabsorption of the elec- tion of sodium, they also cause a loss of potassium, earning trolytes: sodium, potassium, calcium, and magnesium, as well them the label “potassium wasters.” Serious potentially life- as water in the ascending loop of Henle. This portion of the threatening cardiac dysrhythmias can follow the development nephron is largely responsible for the concentration of urine of low serum potassium or hypokalemia. For this reason, electrolytes and subsequent volume of urine. Loop diuretics potassium supplements are often co-prescribed to patients on are very effective and have a rapid onset of action. For these loop diuretics. True toxicity from loop diuretics is rare. For reasons, loop diuretics are often preferred in an emergency. example, patients have been given 2,000 mg of furosemide Furosemide is an example of a commonly used medication without toxic effect. This “high ceiling” makes these diuret- in this class. ics relatively safe to administer. 668 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Osmotic Diuretics who cannot tolerate potassium supplements. Unfortunately, Any substance with a large molecular weight which can- potassium-sparing diuretics, as a class, are weak diuretics. To not pass through a semipermeable membrane will create an improve their effi ciency, as well as maintain the advantage of osmotic effect. The presence of formed elements and blood preserving potassium, they are often given in combination proteins, such as albumin, in the bloodstream creates an with the thiazides. osmotic effect. This effect, called colloidal osmotic pressure Several agents (e.g., amiloride and triamterene) work (COP), occurs because these large molecules cannot pass indirectly in the distal tubule, while spironolactone works by through the blood vessel walls. blocking the effects of aldosterone in the distal tubule. As a Similarly, when chemicals with a large molecular weight result of these two actions, sodium and water are excreted and (i.e., heavy molecules) pass into the fi ltrate via the fenestrated potassium is retained. membranes within the kidney (a very forgiving membrane Spironolactone, as an aldosterone-antagonist, also has that is 100 to 400 times more permeable than ordinary capil- a secondary use in the treatment of hyperaldosteronism, an laries) and travel to the loop of Henle to encounter a semiper- adrenal disease. meable membrane, they are entrapped. However, these heavy molecules continue to create an osmotic effect and thus draw Vasodilator Therapy fl uids into the fi ltrate. Certain vasodilators work on the same mechanism as nitrates, Examples of heavy molecules that are effective osmotic thereby creating a direct vasodilation in the blood vessels. diuretics include mannitol (a complex sugar) and urea. Osmotic Since a larger portion of blood and blood vessels is on the diuretics are used to reduce edema in special cases; for exam- venous side of the central circulation, the venous side is more ple, mannitol is used to treat increased intracranial pressure affected. This causes a drop in the venous pressure and there- secondary to cerebral edema. Osmotic diuretics are also used fore the amount of preload the heart receives. to prevent kidney failure by forcing a continuous diuresis. Alternatively, other vasodilators create relaxation of the Caution must be exercised whenever osmotic diuretics are muscle within the vessel walls, resulting in dilation. Since administered. Overly aggressive treatment can result in hypo- arteries and arterioles have more muscle than veins and volemia (leading to hypoperfusion and shock), hypokalemia venules, these medications have a more pronounced effect on (leading to ventricular dysrhythmias), and hyponatremia the arterial side of the central circulation. Arterial vasodila- (leading to seizures). tion directly translates to lowered diastolic pressure, reduced peripheral vascular resistance, and a reduction in cardiac Distal Tubule Diuretics afterload.119 The thiazides were one of the fi rst diuretics used in medical therapeutics for the treatment of heart failure. As sulfonamide Afterload Reduction derivatives, the thiazides also work like carbonic anhydrase The arteriole beds are largely controlled by the alpha receptors inhibitors. However, they work in the distal tubule instead of of the sympathetic nervous system. Alpha-receptor antago- the proximal tubule. nists prevent vasoconstriction and the resulting increases Thiazides inhibit the reabsorption of sodium and there- in peripheral vascular resistance (afterload) that occur as a fore increase the excretion of sodium in the urine. The urine, result of vasoconstriction. An example of an alpha-blocker is now hyperosmolar, collects more water as it passes through hydralazine, a current and commonly used alpha-blocker. the tubules. Thiazides also increase the excretion of potas- The diffi culty with using alpha-blockers lies in the sym- sium along with the sodium. pathetic nervous system’s response to the decrease in diastolic Indications for thiazides, such as hydrochlorothiazide, pressure. The baroreceptors refl exively stimulate the sympa- include relief from mild to moderate heart failure as well as thetic nervous system to increase the blood pressure. This is the treatment of mild to moderate hypertension. Thiazides are achieved via peripheral vasoconstriction, now inhibited by often preferred as a treatment for hypertension because they the alpha-blockers, and tachycardia. This tachycardia can tax are inexpensive (a benefi t for patients on a fi xed income), the already overtaxed heart and induce ischemia. To prevent easy to administer, and have fewer side effects than other this refl exive tachycardia, a beta-blocker is often given in diuretics. combination with the alpha-blocker in an effort to balance the Thiazides are also potassium wasters and have the same effects of each. precautions as other potassium wasters. Potassium deple- Other arterioles affecting antihypertensives work directly tion can, for example, predispose a patient to a number of upon the smooth muscles in the arteriole walls. These agents, dysrhythmias. usually administered intravenously, are very effective in reducing peripheral vascular resistance (the diastolic blood Potassium-Sparing Diuretics pressure) and reduce the heart’s work. Potassium-sparing diuretics are particularly attractive for use Unfortunately, the same issue exists for these agents (e.g., in patients who are sensitive to hypokalemia (e.g., patients diazoxide) as did for the alpha-blockers. Again, beta-blockers on digitalis) or patients who require a diuretic therapy but are occasionally co-prescribed to balance the effects of each. Pharmacological Interventions for Cardiopulmonary Emergencies 669 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Preload Reduction When the level of cyanide exceeds the liver’s capacity to In the not too distant past, Paramedics used a device called detoxify it, then cyanide poisoning can occur. Fortunately, the a “rotating tourniquet” to mechanically sequester blood in half-life of nitroprusside is 2.7 days. Cyanide levels can be the periphery. That technique, though fraught with complica- tested daily to ensure that the patient remains symptom-free. tions, was effective in reducing preload. Today, medications Nitroprusside infusions are easily identifi ed because the are used to obtain a similar effect. solution container must be protected from light. Therefore, Nitrates are potent vasodilators, and their main impact the IV bag is always covered with aluminum foil or another is on the venous circulation. Dilating the venous circulation, similarly opaque material. nitrates increase the “pooling” of blood in the venous circula- Nitroprusside infusions must be very carefully titrated, tion and reduce the preload returning to the heart. In essence, typically to the patient’s blood pressure, starting at 0.3 micro- nitrates create an “internal phlebotomy” by withholding blood grams per kilogram of patient’s weight per minute (mcg/kg/ from the central circulation. min). Therefore, nitroprusside infusions are typically placed A number of long-acting nitrates have been developed on an infusion pump. for this purpose. Perhaps the earliest long-acting nitrates were oral preparations, such as isosorbide. Isosorbide now Cardiac Glycosides comes in extended release capsules, chewable tablets, and Digitalis is the quintessential cardiac glycoside. One of the sublingual tablets. few plants that make a steroid similar to animal steroids, digi- To further extend the vasodilator effects, nitrates are also talis is processed from the foxglove plant. Used for hundreds available in transdermal systems. These “patch” systems con- of years as the “housewife’s recipe” for swelling and edema, tain nitrate in a gel-like “reservoir.” After the gel melts, the drug digitalis did not enter into modern pharmacy until 1876.120 The passes through the skin and then is absorbed, by passive diffu- story is told of a patient who went to Dr. William Withering, sion, into the bloodstream. There are a number of patch systems a Scottish physician, with “dropsy” (congestive heart failure) on the market and each works in a slightly different manner. and was diagnosed as incurable. The patient then went to a Paramedics often use nitroglycerin paste for the same gypsy who treated him with a secret herbal remedy and he effect. A ribbon of paste, measured in one-half inch incre- recovered. Intrigued, Dr. Withering sought out the gypsy and ments, is placed on an impervious paper and placed against bartered for the remedy. The key ingredient in the concoction the patient’s skin. The selection of a site for the paste’s place- was the purple foxglove, digitalis purpurea (L). ment is important. The paste should be applied to a hairless Digitalis had long been known for its toxicity, having area, usually on the upper anterior chest, where it is clearly been used by the Romans as rat poison and in medieval “trials visible. Avoid placing the patch below the knees or elbows. by ordeal.” However, it was not thought to have many medici- Circulation is frequently poor in these areas and absorption nal uses. Dr. Withering made his fortune on the “discovery” less predictable. of the medicinal uses of digitalis after he recounted its ben- Alternative placement sites include the shoulder or the efi ts in a treatise entitled, “An Account of Foxglove.” In that inside of the upper arm. Some Paramedics will loosely encir- treatise, he strongly advised that the effects of digitalis on cle the limb with a plastic wrap to prevent liquefi ed nitroglyc- the patient be closely monitored and that it was imperative to erin paste from dripping. individualize the dose and schedule. No wiser words could In every case, it is important to report where the paste have been offered as digitalis toxicity is a common impedi- was applied when patient care is transferred. Nitroglycerin ment to the drug’s use.20 can induce signifi cant hypotension, in which case the fi rst action should be to remove the paste. Failure to notify other providers of the presence of nitroglycerin paste

can lead to Mechanism of Action inappropriate treatment of the hypotension. Digitalis has two unique therapeutic benefi ts: a slowing of the Nitroprusside is an effective intravenous vasodilator cardiac conduction, resulting in increased ventricular fi lling, that has a greater impact on the venous circulation (preload) and increased strength of contraction without the use of addi- than on the arterial circulation (afterload), making it attrac- tional oxygen. Together, these effects culminate in an overall tive for the treatment of acute heart failure, especially heart decrease in the heart’s work. This is a desirable situation for failure secondary to valvular regurgitation. Nitroprusside is the compromised myocardium, as it allows for more effi cient also used to treat acute hypertensive crisis, an abnormal and functioning. potentially life-threatening elevation of blood pressure. Digitalis acts by binding to and disabling (blocking) Na/ Chemically, nitroprusside contains fi ve cyanide groups K ATPase, the enzyme that breaks down ATP to release its bound to nitric acid, the active ingredient in nitroglycerin, energy. Without ATP breakdown there is no energy to power within its structure. When the nitric acid breaks off and the Na/K pump during repolarization. The accumula- causes vasodilation, the cyanide remains. The free cyanide tion of intracellular sodium, which results from the failure is then metabolized into thiosulfate by the liver and excreted of the sodium-potassium pump, leads to an ionic imbalance. harmlessly. Calcium is then exchanged to help maintain that balance. 670 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. The slowed depolarization prolongs the cardiac cycle (a negative chronotropic and negative dromotropic effect), lead- ing to reduced heart rate. This maximizes the diastolic poten- tial of Starling’s Law, as the slowed heart has more time for ventricular and coronary artery fi lling. The heart is further slowed when digitalis inhibits the calcium- sensitive AV node from passing the action potential down the ST bundle branches to the ventricles. This slowing of AV node con- duction can be observed by a lengthening of the PR interval. QT The increased calcium also produces more excitation- Abnormal QTc is > 0.44 sec in males coupling of actin and myosin in the ventricle’s myocardial and > 0.45 sec in females fi bers and a stronger contraction of the now overfi lled ventri- cle. This improvement in the strength of contraction, a posi- tive inotropic effect, is done without consuming additional oxygen. Electrocardiographically, the digitalis effect can be seen Shortened QT interval by the prolonged PR interval, the shortened QT interval, and Characteristic down-sloping ST depression an inverted T wave, the impact of altered repolarization oppo- Classic scooped-out ST segment site of the major QRS forces (Figure 30-11). Figure 30-11 The digitalis effect demonstrated Indications on ECG. In the past, a common cause of congestive heart failure was the loss of atrial kick, which contributes approximately 25% Digitalis also has a relative contraindication during heart of the cardiac output. It also accompanied new onset atrial block. The impact of digitalis upon the calcium-sensitive AV fi brillation.121 In this situation, digitalis slows the racing node can further slow conduction through the AV node and heart, which was trying to compensate for the ventricular aggravate a pre-existing heart block, causing profound brady- fi lling pressure lost to atrial fi brillation. Slowing the heart cardia and hypotension. rate allowed for more ventricular fi lling and thus led to an augmented cardiac output. The positive inotropic effect of Digitalis Toxicity digitalis can further improve cardiac output to levels that are Digitalis has a narrow therapeutic range. As a result, the tolerable for the patient. It should be noted that digitalis does incidence of toxicity is fairly high, so much so that between not convert atrial fi brillation back into normal sinus rhythm, 10% and 20% of nursing home patients receiving digitalis but instead merely slows the ventricular response. will develop digitalis toxicity during the course of treatment. Currently, digitalis has been replaced with better Class II The early identifi cation and treatment of digitalis toxicity will and III agents, which slow the heart without the serious side help to decrease the estimated 34% moderate to severe mor- effects and dangers of digitalis toxicity, some of which will bidity associated with digitalis toxicity. be explained shortly. In many cases of atrial fi brillation, the Several conditions contribute to the problem of digitalis etiology is identifi ed and eliminated (if possible), sometimes toxicity. For one, digitalis is primarily excreted via the kid- by radio ablation therapy in the electrophysiology lab of a neys. Therefore, any change in kidney function, such as can cardiac care center. occur with heart failure, can cause an increase in digitalis to Digitalis may still have a therapeutic advantage in treat- toxic levels.122 ing congestive heart failure from other causes. No other single Digitalis also affects the sodium-potassium pump. chemotherapeutic agent has the same dual actions—negative Ordinary doses of digitalis administered to a patient with chronotropy and positive inotropy—as digitalis. hypokalemia can result in toxicity. This toxicity is not a true toxicity, but rather a pseudo-toxicity (the relative imbalance Precautions between the regular dose and the desired therapeutic effect, A new-onset atrial fi brillation may mask the tell-tale ECG which is exaggerated by the hypokalemia). This pseudo- signs of Wolff-Parkinson-White (WPW) syndrome. Digitalis toxicity is sometimes occasioned by the concurrent use of the mistakenly administered in those cases allows uninhibited potassium-wasting diuretic furosemide. conduction over the bypass tract, as the AV node conduction The mechanism of cardiotoxicity relates to the intra- is slowed by the digitalis. The resulting antegrade conduc- cellular calcium overload, which results from high levels of tion over the bypass tract, in concert with normal conduc- digitalis. This increased calcium load has a two-fold effect. tion down the intra-atrial pathways, can contribute to circus First, it increases spontaneous afterdepolarizations in the movement and high rate tachycardia, which may eventually myocardium. These afterdepolarizations create ectopic beats, deteriorate into ventricular tachycardia/fi brillation. including junctional and ventricular extrasystoles. Unabated, Pharmacological Interventions for Cardiopulmonary Emergencies 671 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. the heightened reactivity of the myocardium can lead to junc- also lead to rebound edema later in the course of the patient’s tional tachycardia and ventricular tachycardia/fl utter. care. This rebound edema is the result of activation of the Concurrent calcium buildup within the AV node depresses renin-angiotensin-aldosterone mechanism by the diuresis. the AV node, causing bradycardia, as low as “35 beats in a In many cases, these patients are already on diuretics and minute.”120 It can even create a complete AV block. This ECG are not “fl uid-overloaded.” More correctly, these patients are manifestation, AV blocks of varying degrees, is seen in 30% fl uid “maldistributed” and only need temporary relief from to 40% of patients with digitalis toxicity. excessive preload. Patients at particular risk are those with Extreme digitalis-induced AV dissociation sets the stage restrictive cardiomyopathy, early phase acute myocardial for a rare but potentially lethal phenomenon called “bidirec- infarction, and mild chronic heart failure. tional tachycardia.” Bidirectional tachycardia is the result of Repeated doses of nitrates may be more effective in these concurrent atrial and junctional/ventricular tachycardia with cases. Nitrates will cause immediate venodilation, increasing a complete heart block at the AV node. the volume within the venous pool, and effectively create an internal phlebotomy. That is to say, a portion of blood vol- Signs of Digitalis Toxicity ume will be temporarily warehoused in the venous circula- Initial signs of digitalis toxicity include bradycardia, as well tion (which has a large capacitance) and taken out of the core as nausea and diarrhea. The latter symptoms of abdominal circulation until the heart can recover. distress, visual changes, and general malaise may be misin- terpreted by the patient as fl u-like symptoms and ignored by Forward Failure the patient. The combination of the losses of potassium from Acute forward failure, or cardiogenic shock, is a failure of the both diarrhea and vomiting only serve to worsen the situation heart as a pump. Regardless of the underlying cause of the and lead to more nausea, vomiting, and diarrhea. pump’s failure, it is imperative to increase the heart’s cardiac As the intoxication continues, the patient may experi- output (blood pressure). ence confusion, which may be misinterpreted as dementia The body’s own compensatory mechanisms depend or depression in the elderly. The patient may also complain on the hormone epinephrine (a catecholamine) to increase of seeing yellow-green halos around lights. At this point, the heart rate (positive chronotropy), speed of conduc- signifi cant cardiac manifestations typically occur, including tion (dromotropy), and most importantly, the strength of tachycardia-induced syncope. contraction (inotropy). Supporting the body’s own com- Overt digitalis overdose, either accidental or otherwise, pensatory mechanisms, Paramedics can infuse additional may be treated emergently with digitalis-specifi c antibody sympathomimetics classifi ed as catecholamines: three natu- fragments (digoxin immune fab). Otherwise, treatments focus rally occurring catecholamines—dopamine, epinephrine, on the cause of the toxicity: reversing hypoperfusion leading and norepinephrine—plus two synthetic catecholamines— to kidney failure, withdrawal of the numerous drugs which dobutamine and isoproterenol. interact negatively with digitalis, or correcting hypokalemia. These vasopressors, drugs which affect blood vessels If the patient is hypokalemic, then potassium replacement directly, increase blood fl ow to vital organs. However, some is provided. Phenytoin has been found useful in treating are associated with signifi cant side effects and should be used digitalis-induced dysrhythmia because of its anticholinergic carefully in the patient with acute heart failure. effects.123 Administration of magnesium as a competitive ion may be helpful in reducing ventricular ectopy, including ven- tricular tachycardia/fl utter. Street Smart Acute Heart Failure Before starting any catecholamine infusion, it is Acute heart failure is a medical emergency that, if untreated, can quickly culminate in death. Acute heart failure can pre- important to rule out hypovolemia as a cause of sent in several ways. The fi rst syndrome is forward failure, a hypotension. Failure to do so may compromise already loss of cardiac output that results in hypotension and rapidly ischemic tissue. “Squeezing dry pipes” with vasopressors progresses to end-organ failure. The other syndrome is back- ward failure, a backup of pressures into the low-pressure lung will not improve blood pressure signifi cantly. fi elds which produces acute pulmonary edema. Acute pulmo- nary edema literally suffocates the lungs, leading to hypoxia and respiratory acidosis. Catecholamines All catecholamines interact directly with sympathetic Backward Failure receptors throughout the body. Alpha-receptor stimulation The goal of treating backward failure, manifested by acute will increase vasoconstriction of peripheral capillary beds, pulmonary edema, is to quickly reduce the preload. Treatment increasing blood in the core circulation while also increasing with diuretics can provide rapid symptomatic relief but can the peripheral vascular resistance the heart must overcome. 672 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Beta-receptors in the heart will both increase the speed of Occasionally, after a subcutaneous injection or intravenous the heart (positive chronotropy) as well as the strength of con- bolus, it is necessary to continuously infuse epinephrine to traction (positive inotropy) and dilate the bronchial smooth maintain blood pressure, particularly in cases of distributive muscle, thereby improving oxygen delivery. However, this shock, such as septic shock and anaphylactic shock. comes at

a cost of increased work of the heart. Precautions Dopamine Catecholamines are potent medications, so potent that the Dopamine, a naturally occurring catecholamine, is the pre- dose is measured in micrograms (mcg) instead of milli- cursor to epinephrine and has effects similar to epinephrine. grams (mg). Typically infused intravenously, catecholamines At lower doses, one-half to two micrograms per kilogram are carefully titrated to a dose of micrograms per kilogram per minute infusion (0.5 to 2 mcg/kg/min), dopamine dilates of patient weight per minute of infusion (mcg/kg/min) and renal arteries, increasing blood fl ow and subsequent produc- often infused via an intravenous pump which can ensure pre- tion of urine. cise delivery. At higher doses, up to 10 micrograms per kilogram per The patient receiving a catecholamine infusion, in order minute infusion (10 mcg/kg/min), dopamine stimulates the to sustain an adequate perfusing blood pressure, may be drug- beta-receptors of the heart, increasing heart rate and force of dependent. A sudden interruption in the infusion, for any contraction. At the highest doses, 10 to 20 micrograms per reason, can result in a precipitous fall in blood pressure. For kilogram per minute infusion, alpha-adrenergic receptors are this reason, most providers ensure the presence of a second increasingly stimulated. intravenous access site for use if the fi rst intravenous access Alpha-adrenergic receptor stimulation leads to peripheral is lost. vasoconstriction, an increase in peripheral vascular resistance Inadvertent infi ltration of a catecholamine into subcuta- (afterload), and more work for the heart, while elevating the neous tissue, secondary to a dislodged or misplaced catheter, blood pressure via increased venous return (preload). The can result in localized ischemia and necrosis of the tissue. trade-off, a perfusing blood pressure for increased work of Phentolamine, an alpha-adrenergic blocking agent, injected the heart, may induce an acute myocardial infarction and subcutaneously around the catecholamine infi ltration may renal ischemia.124 For those reasons, high dose dopamine is help prevent tissue necrosis, but special care should be taken reserved for severe hemodynamic imbalance. to assure IV patency prior to and during administration of catecholamines. Street Smart Street Smart While dopamine at 4 to 20 mcg/kg/min can increase blood pressure, dopamine 3 mcg/kg/minute or less Commercially prepared catecholamines contain a can actually lower the blood pressure. These lower, preservative (sulfi te) which helps maintain potency. or renal, doses of dopamine also cause a vasodilation Some patients are sensitive to sulfi tes and may have of the mesenteric vessels resulting in venous an allergic reaction to the drug, compounding the pooling. Therefore, dopamine infusions should severity of the situation instead of improving it. always be started at more than 5 mcg/kg/min in the fi eld. Epinephrine Epinephrine, the original catecholamine, is available for injection, inhalation, and infusion. Epinephrine is a power- Dobutamine ful direct-acting synthetic catecholamine. In small doses, Dobutamine is the synthetic analog of dopamine but is more epinephrine is used to treat severe asthma exacerbation and beta-selective than dopamine. This quality makes it less serves as an adjunct to local anesthetics to control bleeding desirable in cases of distributive shock (e.g., septic shock), during wound repair (sutures). In larger doses, epinephrine but very desirable for cardiogenic shock. can reverse cardiovascular collapse secondary to anaphy- Dobutamine is a potent inotropic agent and a weak chro- laxis or coarsen ventricular fi brillation for more effective notropic agent. Therefore, dobutamine does not signifi cantly defi brillation. increase the oxygen demands of the heart but can improve Epinephrine’s rapid onset of action (three to fi ve minutes cardiac output. This makes it attractive for use in cardiogenic by subcutaneous injection) makes it useful in an emergency. shock secondary to pump failure. Pharmacological Interventions for Cardiopulmonary Emergencies 673 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Dobutamine is very effective for patients in cardiogenic resistance (afterload) translates to increased work for the shock who have an elevated left ventricular fi lling pressure, heart and offsets any advantage obtained by increasing the often manifested by elevated jugular venous distention (JVD), blood pressure. In fact, imprudent administration of norepi- but who are not remarkably hypotensive (systolic B/P greater nephrine can lead to acute myocardial infarction in patients than 90 mmHg). These patients, on the border of severe car- with pre-existing coronary artery disease. diogenic shock, often benefi t from a combination of dobu- tamine (to maintain blood pressure) and dopamine at renal doses (for diuresis). As an added bonus, dopamine and dobutamine are com- Street Smart patible and may be infused together via the same intravenous access. This approach is often preferable, especially in patients Monoamine oxidase oxidizes catecholamines, with potential for hypokalemia, because of a decreased risk like dopamine and norepinephrine, into inactive of tachydysrhythmia. metabolites. Monoamine oxidase inhibitors (MAO Norepinephrine inhibitors), a class of antidepressant medications, Norepinephrine, in contrast to dobutamine, has a high affi nity prevents the breakdown of these catecholamines. for alpha-adrenergic receptors. Norepinephrine is a power- Routine doses of dopamine administered to a patient ful peripheral vasoconstrictor which is effective in treating who has prescribed MAO inhibitors can result in serum cardiovascular collapse secondary to distributive shock (e.g., advanced septic shock). dopamine levels that are increased ten-fold and lead The use of norepinephrine in patients in cardiogenic to acute hypertensive crisis. shock is questionable, as the increased peripheral vascular 674 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Two of the most common chief complaints of patients are chest pain and shortness of breath. By understanding the underlying cardiopulmonary physiology and pathophysiology, Paramedics can establish effective therapeutic interventions earlier in the course of the patient’s illness. Early intervention can translate directly into decreased morbidity and mortality. Key Points: • The central nervous system consists of the brain • Blocking nicotinic receptors causes paralysis. and spinal cord. Depolarizing agents cause fasciculations before • paralysis while non-depolarizing agents lead The peripheral nervous system consists of the directly to paralysis. cranial, nervous, and spinal nerves. • • Adrenergic agents directly or indirectly stimulate a The autonomic nervous system is that portion of sympathetic response. the peripheral system that controls involuntary functions. • Adrenergic blockers would prevent a sympathetic • response. The autonomic nervous system consists of two branches: the sympathetic division, which serves • Alpha-adrenergic agents or blockers primarily to accelerate organs, and the parasympathetic affect the vessels. division, which controls vegetative functions. • Beta-adrenergic agents or blockers affect the heart • The vagus nerve is the primary parasympathetic or lungs. nerve. • Drugs used to treat pulmonary diseases usually • Messengers which relay signals from nerve to organ target one of the three S’s: spasms, swelling, or are called neurotransmitters. secretions. • Neurotransmitters attach to a receptor. • Beta-adrenergic agonists, xanthine derivatives, and • cholinergic antagonists prevent or reduce spasms. Agonist drugs increase the neurotransmitters’ ability to stimulate the receptor. • Corticosteroids, leukotriene antagonists, and mast • cell inhibitors reduce swelling. Antagonist drugs block stimulation of the receptor. • • Mucolytics liquefy mucus. Parasympathetic receptors are classifi ed as cholinergic (responding to acetylcholine), • Drugs used to treat coronary artery disease usually i.e., muscarinic, or nicotinic receptors. target vessels, platelets, coagulation cascade, or • lipids. Muscarinic receptors are found in organs, whereas nicotinic receptors are located in the adrenal • Antilipidemic drugs either prevent absorption of medulla, CNS, and skeletal muscles. cholesterol, sequester in the bile for elimination, • or prevent the liver from making cholesterol. Cholinergic agents are agonists which stimulate a parasympathetic response. • Anticoagulant drugs interfere in the clotting • cascade, preventing the formation of a fi brin clot. Anticholinergic agents would slow or stop parasympathetic responses. Pharmacological Interventions for Cardiopulmonary Emergencies 675 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. • Antiplatelet drugs alter platelet membranes, • Class V drugs have miscellaneous effects and include preventing aggregation, adherence, and the cardiac glycoside digitalis and the antiarrythmic vasoconstriction. adenosine. • Fibrinolytics disassemble the fi brin clot. • An indirectly acting drug which allows the heart • rate to increase is the cholinergic blocker called Nitrates dilate the venous system (reducing blood atropine. return to the heart), dilate the arterial system (reducing workload of the heart), and may dilate • When underperfused, the kidneys release a coronary vessels (increasing blood fl ow to the substance called renin. Through several steps, renin myocardium). is converted to angiotensin, which affects vessel • dilation and the movement of water and sodium Dysrhythmias are an alteration in the heart’s rate or from the kidney. rhythm. Not all dysrhythmias require treatment. • • The conversion of renin to angiotensin requires an The goal of dysrhythmic treatment is to alleviate enzyme. Inhibiting the enzyme (with an angiotensin- symptoms. Antidysrhythmic drugs can cause other converting enzyme inhibitor or ACE inhibitor) dysrhythmias and are proarrythmic. prevents an increase in blood pressure through • Drugs used to treat dysrhythmias affect the constriction and increased volume. transition of the ionic channels from resting to • Diuretics affect the release of water and other ions open/active or inactive. from the kidney. Depending upon the exact location • The cations of the heart’s action potential are of action, more or less water is released and sodium, potassium, and calcium. The Vaughn- potassium may be excreted or retained. Williams classifi cation system divides drugs • Vasodilators usually cause dilation of the venous according to the ion affected. side and reduction of blood return to the heart. • Class I drugs affect sodium infl ux. Class I drugs are Those that cause arterial dilation decrease diastolic subcategorized as IA, IB, or IC, depending upon pressure, peripheral vascular resistance, and where in the sodium infl ux stage they act. afterload. • Class II drugs are beta-blockers. They affect the • Digitalis, a cardiac glycoside, slows electrical chemical which opens the calcium channels. They conduction and increases the strength of also reduce myocardial infarct size by decreasing contraction. It is both an antidysrhythmic and a heart rate and thus allow a longer diastole and treatment for heart failure. increased coronary blood fl ow. By also dilating • Digitalis has a narrow therapeutic range and can peripheral vessels, they decrease myocardial oxygen rapidly lead to toxicity. demand. • • Catecholamines act with sympathetic receptors. Class III drugs block potassium movement from the They are indicated for vascular support. cell, lengthening the period of time in which the cell cannot respond to another stimulus. • Class IV drugs block the movement of calcium into heart cells, reducing the rate of depolarization or the mechanical initiation of contraction. 676 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Review Questions: 1. Differentiate the central nervous system, 8. Defi ne agonists and antagonists as they relate to peripheral nervous system, and autonomic receptors. nervous system from each other based on location, 9. Which classes of drugs reduce spasms associated components, and general action in the body. with pulmonary disease? 2. How

are the actions of the sympathetic division 10. Which classes of drugs reduce swelling different from those of the parasympathetic associated with pulmonary disease? division? 11. From which class of drugs do “rescue drugs” for 3. Defi ne a neurotransmitter and describe how pulmonary disease come? it works. 12. List the fi ve main classifi cations of the Vaughn- 4. Which division of the autonomic nervous Williams system. system has cholinergic receptors? 13. What condition(s) are treated by drugs of the 5. Name the types of adrenergic receptors. Vaughn-Williams system? 6. Which adrenergic receptors primarily affect 14. How do ACE inhibitors work? vessels? 15. Describe the concern regarding the 7. Which cholinergic receptors primarily affect administration of digitalis preparations. skeletal muscles? Case Study Questions: Please refer to the Case Study at the beginning of 2. In what ways do pharmacies try to prevent the chapter and answer the questions below: patients from taking similar medications 1. Using the information in this chapter, describe prescribed by different physicians? at least fi ve ways in which medications prescribed 3. How do Paramedics assist in educating their for Mrs. Fein’s blood pressure control and patients about medication use? dysrhythmias can cause her complaints of fatigue and nearly fainting. References: 1. Greenblatt S. A History of Neurosurgery. New York: American 5. Arun CP. Fight or fl ight, forbearance and fortitude: the spectrum Association of Neurological Surgery; 1997. of actions of the catecholamines and their cousins. Ann N Y Acad 2. Shields RW, Jr. Functional anatomy of the autonomic nervous Sci, 2004;1018:137–140. system. J Clin Neurophysiol. 1993;10(1):2–13. 6. Wortsman J. Role of epinephrine in acute stress. Endocrinol 3. Hilz MJ, Dutsch M. Quantitative studies of autonomic function. 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Faris R, Flather MD, Purcell H, Poole-Wilson PA, Coats AJ. 99. Pitts WR, Lange RA, Cigarroa JE, Hillis LD. Cocaine- Diuretics for heart failure. Cochrane Database Syst Rev. induced myocardial ischemia and infarction: pathophysiology, 2006;1:CD003838. recognition, and management. Prog Cardiovasc Dis. 118. Salvador DR, Rey NR, Ramos GC, Punzalan FE. Continuous 1997;40(1):65–76. infusion versus bolus injection of loop diuretics in congestive 100. Flemenbaum A. Pavor nocturnus: a complication of single heart failure. Cochrane Database Syst Rev. 2005;3:CD003178. daily tricyclic or neuroleptic dosage. Am J Psychiatry. 119. Hollenberg SM. Vasodilators in acute heart failure. Heart Fail 1976;133(5):570–572. Rev. 2007;12(2):143–147. 101. Hohnloser SH. Proarrhythmia with Class III antiarrhythmic 120. Fisch C. William Withering: An account of the foxglove and drugs: types, risks, and management. Am J Cardiol. some of its medical uses 1785–1985. J Am Coll Cardiol. 1997;80(8A):82G–89G. 1985;5(5 Suppl A):1A–2A. 680 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. 121. Alpert JS, Petersen P, Godtfredsen J. Atrial fi brillation: natural 123. Roberts DM, Buckley NA. Antidotes for acute cardenolide history, complications, and management. Annu Rev Med. (cardiac glycoside) poisoning. Cochrane Database Syst Rev. 1988;39:41–52. 2006;4:CD005490. 122. Litovitz TL, Klein-Schwartz W, Dyer KS, et al. Annual report 124. Schreiber W, Herkner H, Koreny M, Bur A, Hirschl MM, Glogar of the American Association of Poison Control Centers toxic D, et al. Predictors of survival in unselected patients with acute exposure surveillance system. American Journal of Emergency myocardial infarction requiring continuous catecholamine Medicine. 1998;16(5):443–497. support. Resuscitation. 2002;55(3):269–276. Pharmacological Interventions for Cardiopulmonary Emergencies 681 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. KEY CONCEPTS: Upon completion of this chapter, it is expected that the reader will understand these following concepts: • Mechanism of action for common medications • Prehospital drug interventions • Recognition of expected actions and other actions of patient and prehospital medications Case Study: The ambulance squad received a call for a 35-year-old man complaining of severe back pain. En route to the call, one Paramedic said to his partner that this guy was probably just a drug seeker. His partner replied, “Maybe, but we need a lot more information. Many medical conditions cause severe pain and I’d want someone to care for me and reduce my pain if possible.” 682 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Pharmacological Therapeutics for Medical Emergencies 683 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. OVERVIEW Paramedics are expected to treat an enormous variety of diseases in the fi eld. Considering the lack of information normally known about a patient in the fi eld, the enormity of the EMS task becomes even more daunting. Nevertheless, using a limited pharmacy, Paramedics persist in trying to accomplish their missions of care and support to the sick and injured. The following drug review supplies the Paramedic with information about drugs that are commonly prescribed to patients, as well as those drugs that a Paramedic might use to care for that patient. The development and distribution of new drugs, and the use of old drugs/ technologies for new applications, makes it impractical to discuss each drug individually. Instead, the general action of each classifi cation of drug (i.e., its pharmacotherapeutics), including its pharmacodynamics and pharmacokinetics, is discussed. The Paramedic is well advised to consult the most recent and up-to-date drug reference regarding a specifi c drug before administering any medicine. Drugs That Affect The entire brain, as well as the spinal cord, is surrounded by the fl uid-producing meninges. the Central Nervous System The central nervous system consists of the brain and the Blood-Brain Barrier spinal cord. Although the brain is considered the seat of Capillaries in the body have small gaps, called slit junctions consciousness (that uniquely human condition), it has not that permit hormones, enzymes, and drugs to move into the always been thought of that way. Aristotle viewed the brain interstitial space. Capillaries in the brain are distinctive in that as just an elaborate cooling apparatus for the blood. It took they have nearly impenetrable tight slit junctions.2 Reinforc- centuries to dispel that myth. Today, the importance of ing these tight junctions are cells called astrocytes. These two the brain is undisputed. The brain is so important that the factors combine to make the brain nearly impassable to most prime directive for EMS could be “to keep the brain alive drugs, permitting only lipid-soluble drugs (like diazepam) to at all costs!” enter the brain and preventing ionized (polar) drugs that are The brain that controls the central nervous system is dissolved in solution from entering into the brain. actually not one brain but three brains working together. The fi rst brain, the so-called primitive brain, is the brainstem, which is made up of the midbrain, pons, and the medulla Central Nervous System Sedatives oblongata. Vital life functions, such as breathing and heart A state of reduced central nervous system activity (i.e., seda- rate, are controlled in the brainstem.1 The brainstem also tion) is desirable for a number of medical reasons. Exhausted contains the reticular activating system (RAS), a complex patients (e.g., insomniacs) need sleep and literally dozens network of interconnected refl exes that maintain wakeful- of drugs can induce sleep. In another case, a fear-induced ness. The next brain is the cerebellum. The cerebellum is anxiety attack can lead to acute myocardial infarction (AMI) responsible for balance (equilibrium) and muscular coordi- in some patients. Perhaps the earliest CNS depressant used nation, hence its title “the athletic brain.” The last brain, the medicinally was alcohol. While alcohol is effective as a CNS cerebrum, is perhaps the most important to a person’s sense depressant, it has many undesirable qualities that limit its of being. The cerebrum is responsible for a person’s emo- medical use. For this reason, and for a wide variety of clinical tions, memories, and speech, as well as reasoning, judgment, situations, other central nervous system depressants have and creativity. The cerebrum is actually a hollow sphere. The been created. outside, called the cerebral cortex (“cortex” is a Latin word These CNS depressants have some common effects. At meaning “bark”), contains the gray matter. The inside of the low doses, many of these drugs are sedatives. They cause cerebrum contains white matter, myelinated fi bers that con- relaxation, lessened irritability, and decreased excitability. nect with different sections of the brain and the spinal cord. At higher doses, many of these CNS depressants induce a 684 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time

if subsequent rights restrictions require it. hypnotic state, a sleep-producing effect. Many of these CNS Benzodiazepines depressants also are anxiolytics, reducing apprehension, fear, Benzodiazepines were introduced in the 1960s and largely and anxiety. While anxiety is normal, and is in fact a healthy seen as a replacement for barbiturates. Compared to barbi- response to stress because it encourages action, excessive turates, benzodiazepines are relatively safe, the lethal dose anxiety is unhealthy. Excessive anxiety can mentally paralyze being one-thousand times greater than the therapeutic dose a person and interfere with his ability to perform the activities (i.e., it has a large therapeutic index). Benzodiazepines were of daily living (ADL). also reported to have fewer side effects and less of an abuse Barbiturates potential than barbiturates. Like barbiturates, benzodiazepines can be divided into Barbiturates, such as phenobarbital, have been used extensively three groups according to the duration of their action. Long- in the recent past as a CNS depressant. While barbiturates have acting benzodiazepines include diazepam, the classic anti- been largely replaced by safer benzodiazepines, barbiturates convulsive medication. Intermediate-acting benzodiazepines are still useful in certain clinical situations. As a class, barbitu- (e.g., lorazepam) are useful in treating acute alcohol with- rates can be divided into three groups according to the duration drawal (delirium tremens). Short-acting benzodiazepines of action: long-acting, short-acting, and ultra-short-acting.3 (e.g., midazolam) are useful in treating neurological medical Long-acting barbiturates, such as phenobarbital, are fre- emergencies such as status epilepticus, a condition of con- quently used for seizure prophylaxis, the prevention of recur- tinuous convulsions. At present, there are over 20 different rent seizures. The intended pharmaceutical effect of long-acting benzodiazepine formulations available on the market. barbiturates can last for as long as 10 to 12 hours, making them ideal for twice daily (BID) administration. Mechanism of Action Short-acting barbiturates, such as pentobarbital or seco- barbital, produce an onset of action within 10 to 15 minutes Benzodiazepines work indirectly by occupying a receptor and can last up to four hours. This rapid onset of action makes next to a receptor. GABA receptors on cell membranes con- them ideal as presurgical anxiolytics in preparation for the trol the fl ow of the chloride (Cl-) ion in and out of the cell via induction of anesthesia. a chloride channel. The amount inside a cell, in milliequiva- Ultra-short-acting barbiturates, such as thiopental, create lents (mEq) of chloride, affects its resting membrane poten- a sedative/hypnotic effect, depending on the dose, within sec- tial. Benzodiazepine occupies a receptor next to the GABA onds. This rapid speed of onset of action makes these drugs receptor (now called the benzodiazepine receptor). The ben- excellent for use in emergency situations where time is of the zodiazepine receptor, when occupied by a benzodiazepine, essence and rapid induction of anesthesia is mandatory. stimulates the GABA receptor to hold onto GABA longer when it is stimulated. The result is prolonged GABA stimula- Mechanism of Action tion, which in turn increases the amount of chloride (Cl-) in The mechanism of action of all barbiturates is the same: Bar- the cell.2The cell, now loaded with chloride, is hyperpolar- biturates interfere with the transfer of sodium and potassium ized and therefore much more diffi cult to depolarize. across the cell membrane. Inhibition of the sodium-potassium Indications ionic transfer blunts the action potential of muscle cells gen- erally and of nerve cells particularly. This nonselective mech- When benzodiazepines hyperpolarize cells, they are in effect anism of action means barbiturates impact the entire central raising the action potential of those cells. Within the cen- nervous system. At higher doses, barbiturates induce anesthe- tral nervous system, raising the action potential also raises sia by this action, in effect paralyzing the brain at the cellular the seizure threshold. Seizures are the result of spontaneous level. At toxic levels, barbiturates suppress chemoreceptors depolarization of the neurons in the brain. Seizures are analo- that are sensing carbon dioxide and oxygen levels, inducing gous to ventricular fi brillation in the heart, a chaotic fi ring respiratory depression. If unresolved, toxic levels of barbitu- of cells without purpose. Raising the action potential of the rates can lead to complete coma and respiratory arrest. heart raises the ventricular fi brillatory threshold. The heart is thus less likely to go into ventricular fi brillation. Raising the action potential within the brain raises the seizure thresh- old; thus, the brain is less likely to seize. This mechanism of action makes benzodiazepines very desirable as anticonvul- Street Smart sive medication, especially in cases of life-threatening con- tinuous seizures termed “status epilepticus.” While barbiturates are powerful anesthetic agents, Benzodiazepines also inhibit the neurons within the they do not produce pain relief. Concomitant limbic system, the seat of human emotions. Benzodiazepine receptors are more concentrated in the limbic system than administration of pain medications is required during anywhere else in the brain. The inhibition of the limbic sys- special procedures. tem also makes benzodiazepines effective as a tranquilizer.4 The combination of tranquilizer effect and anxiolytic effect Pharmacological Therapeutics for Medical Emergencies 685 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. makes benzodiazepines desirable as a premedication before Withdrawal from Central Nervous painful procedures such as elective cardioversion. However, System Depressants benzodiazepines are not pain relievers. Analgesic, concomi- tant administration of pain medication may be indicated. Withdrawal of all CNS depressants can result in a dramatic Benzodiazepines are also useful in treating muscle spasms rebound within the central nervous system. The common (secondary to neuromuscular disease) and spasticity of mus- symptoms of depressant withdrawal include anxiety, agita- cles from traumatic paraplegia or cerebral palsy. By inhibiting tion, restlessness, and symptoms of overstimulation of the neural control of muscles at the level of the spinal cord, spasms sympathetic nervous system, such as tachycardia and hyper- can be prevented and patient management made easier. tension. Onset of symptoms is usually patient and drug spe- cifi c. For example, symptoms of alcohol withdrawal, called the delirium tremens, can occur in as little as 12 hours after the patient has taken his or her last drink. Street Smart Untreated depressant withdrawal can be life-threatening. Delirium tremens, for example, only occurs in about 5% of All CNS depressants, including alcohol, barbiturates, the patients in ethyl alcohol withdrawal. Yet, if left untreated, it can have up to a 35% mortality rate. Alcohol withdrawal and benzodiazepines, cause a loss of motor dexterity. frequently presents as a seizure, a frequent comorbid condi- Operation of complex machines, such as automobiles tion of alcoholism.7 Treatment usually includes reintroduc- and ambulances, should be avoided while under the tion of a CNS depressant, such as Librium, from which the infl uence of these medications. patient is then carefully weaned off. Anesthesia While Paramedics rarely, if ever, perform general anesthesia Benzodiazepine Toxicity while in the fi eld, they are occasionally witness to anesthesia At high levels, benzodiazepines can produce drowsiness and in the emergency department, critical care units, or operating respiratory depression. Fortunately, the therapeutic index for room. An understanding of the fundamentals of anesthesia benzodiazepines is so high that true overdose is relatively can potentially improve the Paramedics’ experience as well rare. However, that is not the case when benzodiazepines as improve interdisciplinary communication between anes- are mixed with other CNS depressants, such as alcohol. thetists and EMS. These substances intensify, or potentiate, the effects of the Anesthesia, by defi nition, is the lack of sensation, pain- benzodiazepines. In those cases, the incidence of respiratory ful or otherwise. Anesthetic drugs primarily induce anesthe- depression/arrest becomes much higher. This fact is not lost sia by interfering with or blocking nerve conduction. Local on the public, some of whom use the combination of benzo- anesthesia, as the name implies, means that local nerves are diazepines and alcohol to cause a peaceful suicide. incapacitated (i.e., left to feel numb). General anesthesia is The metabolism of benzodiazepines occurs in the liver, much more complex. With the brain incapacitated, the patient where even the metabolic by-products are often still pharma- becomes unconscious and general relaxation of muscles and cologically active. The elderly, and others who have decreased loss of protective refl exes occurs. liver function, may react more profoundly to the administra- Incremental doses of anesthetic medications can result tion of benzodiazepines. For example, diazepam, which nor- in several levels or degrees of anesthesia, with the patient mally has a half-life of 24 hours, can remain active in the becoming deeper under the infl uence of the anesthetic bloodstream of an elderly patient for 72 hours. with each successive dose or medication. The fi rst state The antidote for benzodiazepine overdose is fl umazenil. of anesthesia is called analgesia. Analgesia is a condition Flumazenil is a benzodiazepine receptor blocker. It is effec- where the patient does not feel pain, yet remains conscious. tive in blocking the effects of all benzodiazepines but is not More importantly, the patient retains his or her protec- effective against narcotics. Flumazenil has a half-life that tive refl exes. This level of anesthesia is also referred to as is shorter than most intermediate-acting benzodiazepines. conscious sedation. The second state of anesthesia is called Therefore, Paramedics must be alert to the chance of rebound excitement. At this level of anesthesia, the patient may be respiratory depression and be prepared to administer a repeat combative, delirious, and evidence irregular breathing. dose of fl umazenil every hour.5 Paramedics must also be cau- Vomiting and/or incontinence is also common in this stage. tious using fl umazenil as it may induce acute benzodiazepine The third state of anesthesia is surgical anesthesia. The withdrawal (discussed shortly) and eliminate the protection third state is further divided into four planes. These planes from seizures created by the prophylactic administration of are varying levels of unconsciousness. Anesthesiologists benzodiazepines.6 The resultant “breakthrough” seizures can are masters at the individualization of anesthetic doses to develop into life-threatening status epilepticus. For this rea- produce the exact plane of surgical anesthesia desired for son, fl umazenil is not recommended for use in altered mental the specifi c procedure being performed. By monitoring status from unknown ingestions. respirations, which return to normal after excitement, and 686 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. refl exes, such as pupil size, the anesthesiologist can lead the To administer nitrous oxide. the patient is usually asked patient to near-coma. to hold a mask that is fl owing with a mixture of oxygen (mini- As the patient becomes more deeply anesthetized, he mum 20%) and nitrous oxide. When the patient can no longer will lose protective refl exes in a head-to-toe (cephalocau- hold the mask alone, the administration is completed. dal) direction. The fi rst refl ex lost is the blink refl ex. When the eyelashes are brushed gently, the eyelid closes (blinks); Intravenous Anesthesia hence, the blink refl ex. Level one of surgical anesthesia Agents used in intravenous anesthesia include the ultra- starts with the loss of consciousness and loss of the blink short-acting barbiturates. Thiopental is particularly useful in refl ex. Conversely, when a patient is brought out of anes- cases where there is increased intracranial pressure (ICP) because thesia, the last refl ex to return before consciousness is the it produces an actual decrease in ICP pressure (a neuroprotective blink refl ex. benefi t). The onset of action of these agents is usually between The fourth and last state of anesthesia is medullary 60 and 90 seconds and the duration of the action is short. paralysis. With the vital life centers in the medulla oblongata Another class of agents used in intravenous anesthesia are paralyzed, the medication is

now, by defi nition, toxic. Car- the short-acting benzodiazepines. Benzodiazepines like lora- diopulmonary arrest ensues unless the medication is reduced zepam are lipid-soluble and readily cross the blood-brain bar- or withdrawn. rier. While, as a class, benzodiazepines tend to have a slower onset of action than the barbiturates, they have an amnesic effect. This makes them the drug of choice for painful pro- cedures, like elective cardioversion. Certain narcotic agents Street Smart (e.g., fentanyl) are also used during intravenous anesthesia. A discussion of fentanyl follows in the section on narcotics. While the patient may appear unconscious, the last sense to be lost is the sense of hearing. Patients have Balanced Anesthesia reported, verbatim, statements made about them No single anesthetic agent is completely effective or even while they were assumed to be unconscious.8−11 desirable for anesthesia. Individually, many anesthetic agents produce such signifi cant side effects as hypotension, cardiac irritability, and nausea with vomiting. Therefore, a combina- tion of anesthetic agents—some inhaled and some injected Inhaled Anesthetics intravenously—are often used to minimize these side effects General anesthetics may be either inhaled or injected intrave- in an approach called balanced anesthesia. nously. Anesthetists prefer inhaled anesthetic agents because In many cases, premedication with a CNS depressant, these drugs can be precisely titrated to the exact level of anes- like barbiturates or benzodiazepines, is performed fi rst. Use thesia desired. of these CNS depressants as a premedication before the intro- Most anesthetics are not gasses, with the exception of duction of anesthesia (pre-induction agents) can decrease nitrous oxide. Inhaled anesthetics, like halothane or iso- the incidence of fear or panic (anxiolysis) or combativeness fl urane, are volatile liquids that off-gas vapors, which are (sedation) in the patient. inhaled by the patient. The use of these volatile liquids Atropine is another frequently used pre-induction agent. requires complex apparatus and monitoring equipment that Atropine, a parasympathetic blocker, dries the airways and would make this procedure all but impossible to routinely prevents secretions, thus making intubation easier and aspi- perform in the fi eld. ration less likely.16,17 Another frequently used pre-induction The only inhaled anesthetic used in the prehospital agent is lidocaine. Lidocaine blunts sudden raises in intracra- environment is nitrous oxide. Nitrous oxide (N O) received nial pressure (ICP) that often accompany manipulation of the 2 airway and intubation.18–20 notoriety in the 1900s as a form of entertainment in the par- lor and was dubbed laughing gas for its most notable side The most common—and the most problematic— effect. Properly administered N O is a potent analgesic as complication of anesthesia is nausea with vomiting. Major 2 well as an anesthetic that can be safely given in the fi eld.12–15 tranquilizers (neuroleptics) have a noteworthy side effect— While ALS providers are concerned about the progression they prevent nausea. Drugs like promethazine and chlorpro- of anesthetics from analgesia to surgical anesthesia, with mazine are used as both a sedative and as an antiemetic. the concomitant problems that can occur, nitrous oxide can- not produce surgical anesthesia. This quality makes nitrous Procedural Sedation oxide even more desirable for the fi eld. Add to that attribute Procedural sedation is a technique used by Paramedics to the fact that nitrous oxide does not depress respirations nor facilitate performance of technically diffi cult procedures increase cerebral blood fl ow in patients with potential head (such as trauma intubation) or painful procedures (such as injuries, and nitrous oxide could be very useful in the out-of- elective cardioversion). The goal of procedural sedation is hospital setting. to minimally depress the patient’s consciousness, without Pharmacological Therapeutics for Medical Emergencies 687 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. loss of protective refl exes. Procedural sedation must also be Giving even more support to the argument that Para- performed with a minimum of alteration of vital signs. The medics can and should administer pain medications is the use of procedural sedation can improve patient cooperation Paramedics’ ability to administer an antagonist medication. with painful or diffi cult procedures while ensuring safety and Paramedics who can administer narcotics can also adminis- patient well-being. For these reasons, Paramedics are seeing ter naloxone (the antagonist to narcotics) and thereby reverse a greater use of procedural sedation in the fi eld. any untoward effects. Thus, the availability of an antidote, Procedural sedation is the fi rst state of anesthesia. As plus the reality of pain management in these selected popula- such, Paramedics must keep in mind that the patient can eas- tions, and the ability to manage the consequences, combine ily slip into the next state of anesthesia and lose their ability to provide Paramedics an unparalleled safety margin. to protect their airway or become apneic. Therefore, all pro- viders utilizing procedural sedation techniques must be pre- The Experience of Pain pared to protect the airway as well as treat any hemodynamic Perhaps the more central issue is the Paramedic’s understand- instability that might occur as a result of conscious sedation. ing of the concept of pain. A person’s interpretation of pain It goes without saying that the patient undergoing procedural is based, in part, upon cultural determinants and, in part, by a sedation must be continuously monitored. A more thorough personal pain history. The interpretation of pain may be gen- discussion of procedural sedation is contained in Chapter 24. der biased; for example, some feel men should be tough and not complain. The interpretation of pain may be age-biased, Pain Management for example; the misconception that the elderly can tolerate pain better. The interpretation of pain is based in large part Pain is the most common reason people call EMS. Yet, Para- upon the patient’s own experiences with pain. Each patient medics are reluctant to administer pain medications. This is has a pain history which colors his interpretation of pain and an unreasonable response, considering the large number of how he perceives others’ pain. safe pain medications available.21–23 Paramedics’ unwilling- Therefore, when assessing someone else’s pain, all ness to use medications to ameliorate pain is, in part, due to healthcare professionals tend to look at that person’s pain lack of knowledge regarding the actions of these drugs. from their own perspective. This approach, while understand- The bombardment that the public, healthcare profession- able, is fl awed. Pain is a personal experience. Therefore, the als, and Paramedics have received about the dangers of drug effectiveness of pain management can only be interpreted addiction has placed a needless fear in the minds of many. by the person affected. Paramedics must develop tools to Yet, this fear continues, even though multiple studies have assess pain and trust the patient to be honest. That honesty demonstrated that drug addiction to properly prescribed med- will be rewarded as the patient–provider relationship is ications is rare.24 The risks of addiction to single doses of pain strengthened. medication administered in the fi eld for obvious and neces- sary reasons is remote at best. Other Paramedics are reluctant to administer pain medi- Concepts in Pain cation for fear of inducing respiratory depression. This fear Pain is both the cognitive awareness of the stimulus as well is unfounded for two reasons. First, with proper assessment, as the body’s physiological response to the stimulus. Under- including dose adjustments based on condition, careful titra- standing the physiological response will allow Paramedics to tion of the analgesic, and vigilant monitoring of the respi- lessen the pain by interfering with the process. ratory system, the incidence of respiratory depression is Pain can be divided into acute and chronic pain. Chronic low. More importantly, if respiratory depression does occur, pain is a persistent or reoccurring discomfort seen in long- Paramedics are highly trained to properly respond. This fear term conditions (e.g., arthritis). Chronic pain, while impor- represents a fundamental fl aw in the Paramedics’ understand- tant, is not germane to the topic of EMS. Acute pain, on the ing of pain management. While a dose of 4 milligrams of other hand, is a constant in the day-to-day provision of EMS. morphine, for example, administered intravenously might Acute pain occurs suddenly and is preceded by some identifi - induce respiratory depression in 5 to 10 minutes, the same able event. Pain is a warning to the patient, the body’s way dose in a person with moderate burns, a fractured long bone, of telling the patient that something has changed. The pain or advanced cancer would not. In fact, those patients may usually persists until the situation is corrected. require 5 to 10 times or more than that amount of morphine Acute pain can arise from the internal organs, such as the to obtain relief from pain and still not be at risk for respira- heart, and is usually described as a pressure-like, dull, or aching. tory depression. In short, a patient who is truly in pain should This organ pain is termed visceral pain. Visceral pain is poorly and can receive pain medication for pain control. Paramedics localized and often is transmitted to other parts of the body, via should not be overly concerned about the risk of respiratory common nerve pathways. This is called referred pain. depression. However, this understanding does not relieve the Acute pain often arises from the skin, ligaments, mus- Paramedic from needing to be prepared in case respiratory cle, fascia, bones, or joints. This type of pain (somatic depression should occur. pain) is often described as sharp or burning. One important 688 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. difference between visceral pain and somatic pain is that somatic pain can be localized to a specifi c area. Street Smart Every person has a tolerance to pain. At its lowest level, one person might perceive pain while another might not. This is the pain threshold, that amount of stimulus required to The perception of pain is partly psychogenic. Use of elicit a pain response. the term “pain” by a Paramedic tends to establish a If the person has multiple injuries, and therefore multiple fi xed expectation in the patient’s mind. Alternatively, painful experiences, she may not perceive the dull visceral referring to pain as a discomfort tends to induce pain of a heart attack, for example, over the intense pain of a fractured femur. When a pain (often dull visceral pain) is thoughtfulness on the part of the patient and is overshadowed by another more intense pain from another generally less infl ammatory. injury, it is called a distracting injury. The fractured femur in this case may be a distracting injury and takes perceptual dominance over the chest pain. The concept of perceptual Regardless of the mechanism of action, every analgesic can dominance makes it more diffi cult to accurately assess a mask the cause of the symptom. Simply ignoring the pain patient’s condition. does not stop the damage that will occur. Before, during, and Physiology of Pain after pain management, Paramedics must assess and deter- mine the underlying cause of the problem. An injury to the skin will stimulate pain receptors in the der- mis. These pain receptors, called nociceptors, respond to Opiates chemical, mechanical, or thermal stimulus and are not evenly Opium, isolated from the Poppy plant, may have been the fi rst distributed across the body. Once stimulated, the nociceptors’ pain medication used by man. Over the span of time, physi- signal is transmitted either quickly over myelinated A fi bers cians and laypersons alike have sought better, stronger, more (sharp) to the spinal cord or more slowly over unmyelinated effective opium. This untiring pursuit has resulted in over a C fi bers (dull

or burning) to the thalamus. Refl ex arcs occur dozen opiate and opiate-like medications (Table 31-1). over A fi bers, the speed of which permits an automatic with- drawal from the stimulus before the brain even has a chance Mechanism of Action to interpret the painful stimuli and respond. The pain sen- All opiates work by a similar mechanism, coupling with opioid sation is now transmitted to the brain via either the neospi- receptors in the central nervous system and the gastrointestinal nothalamic tract (acute pain) or the paleospinothalamic tract system to become an opiate agonist. The stimulation of these (dull pain) in the spinal cord. opioid receptors decreases the cell membrane’s permeability After arriving at the post-central gyrus in the midbrain, to sodium.25 The resultant increase in intracellular sodium the signal is transferred to the cortex (acute pain) or the limbic hyperpolarizes the cell, decreases the action potential, and system (dull pain) for interpretation and response. The body’s slows conduction by decreasing nerve cell depolarization. response to pain is two-fold: regulation of infl ammation and neuromodulation of the pain. Infl ammation is the body’s Indications response to an injury. Activated by the pain, prostaglandins act as infl ammatory regulators, affecting blood vessel tone, Five different opioid receptors have been identifi ed and platelet aggregation, and muscle spasm in the injured area. labeled with the Greek letters Mu, Kappa, Sigma, Delta, and Neuromodulators are substances that inhibit the trans- Epsilon. Stimulating these opioid receptors causes a variety mission of painful sensations to the brain and spinal cord. of effects. Stimulation of the opioid receptors in the gastroin- Examples of neuromodulators are endorphins. Endorphins testinal system decreases gastric motility (slowed peristalsis) attach to opiate receptors on the neuron which in turn inhibit as well as intestinal secretions. Disease-induced diarrhea, a neural activity. Naturally, opiates also occupy these opiate common malady, can be treated very effectively with small receptors, enhancing the activity of the endorphins. High lev- amounts of opioids. A few drops of tincture of opium can els of circulating neurotransmitters—such as norepinephrine stop diarrhea and produce constipation.26,,27 Paregoric, a cam- and serotonin in the brain caused by stress, acupuncture, and phorated tincture of opium, is an old remedy used for centu- excessive physical exertion—interfere with the effectiveness ries to treat diarrhea. It is still used to treat life-threatening of endorphins and opiates alike. diarrhea in infants and neonates. Stimulating the Mu, Kappa, and Sigma opioid receptors Analgesics along the cortex–brainstem–spinal cord axis produces other desirable, as well as undesirable, effects. Some opiates, in The class of drugs that relieve pain are called analgesics. small quantities, function as a cough suppressant (e.g., an Analgesics work by inhibiting the synthesis or release of pros- antitussive). Prescription antitussive cold medications occa- taglandins or stimulating opiate receptors (opiate agonists). sionally include the opiate codeine. Pharmacological Therapeutics for Medical Emergencies 689 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Table 31-1 Opiates Drug Method Onset of Action Peak Effect Duration Codeine PO 10 to 31 min 31 to 60 min 4 hours Hydrocodone PO 10 to 31 min 31 to 60 min 4 hours Hydromorphone IM 15 min 31 to 60 min 4 hours IV 10 to 15 min 15 to 31 min 2 hours Meperidine IM 10 to 15 min 31 to 50 min 3 hours IV 1 min 5 to 7 min 3 hours Methadone IM 10 to 20 min 60 to 120 min 4 hours Morphine IM 10 to 31 min 31 to 60 min 4 hours IV 1 min 20 min 4 hours Oxymorphone IM 10 to 15 min 31 to 90 min 4 hours IV 5 to 10 min 15 to 31 min 4 hours Propoxyphene PO 15 to 60 min 120 min 4 hours Opiates in larger doses impact the brainstem and pro- Opiates, particularly morphine, are also widely used to duce constricted pinpoint pupils (miosis) and respiratory treat the chest pain (angina pectoris) of an acute myocardial depression. Even moderate doses of opiates can induce infarction (AMI). The administration of morphine not only some degree of respiratory depression. In some cases, this alleviates pain—relaxing the patient and reducing circulating slower and deeper respiration is desirable, improving the epinephrine levels and subsequent arterial constriction—but clearance of carbon dioxide from the lungs and increasing it also decreases the heart’s work (MvO2) by creating periph- oxygenation of the blood. In slightly higher doses, slowed eral vasodilatation. This, in turn, reduces preload. Both of respirations paradoxically result in increased carbon these effects of morphine are accomplished without impact- dioxide retention and hypoxia. The result of unattended ing heart rate signifi cantly, making it an acceptable analgesic opiate overdose can be profound respiratory depression for acute myocardial infarction pain, though there is some leading to acute respiratory acidosis and cardiac arrest. controversary about the use of morphine for patients with Therefore, patients must be carefully monitored while suspected acute myocardial infarction. receiving opiates. The less desirable hallucinogenic effects of opiates, the Administration narcotic effect, is thought to be the result of stimulation of Morphine is the archetypical opiate. The pain-relieving abili- the sigma receptors located in the limbic system. This dream- ties of all subsequent medications are measured against it. producing quality of opiates is so well known that when When a dose of a new medication formulation has the same G erman pharmacist Friedrich Serturner extracted a plant ability to produce analgesia as 10 milligrams of morphine, it alkaloid from the opium of the Poppy plant, he named it Mor- is equianalgesic (i.e., equal to morphine). Morphine serves phium, after Morpheus, the Greek god of dreams.28 as the standard for comparison. Perhaps the most widely known benefi t of opiates is their The one of the fi rst morphine derivatives, produced by impact on pain. A potent analgesic agent, opiates affect the the German pharmaceutical company Bayer, was three times Mu, Kappa, and Delta receptors in the cerebral cortex, the more potent than morphine. It was called a heroic drug, or medial thalamus, and the spinal cord, altering the brain’s per- heroin, because of its powerful pain-relieving effects. ception of pain. Opiates, in effect, replace or augment the Fentanyl, another morphine derivative, is a remarkably body’s own neuromodulators (endophins) and lessen the sen- potent opiate agonist. It has a rapid onset of action as well as sation of pain. It should be noted that, even though the patient a short duration of action, and is 80 times more potent than still perceives the pain, opiates alter the patient’s perception morphine. The combination of these three qualities makes of the pain from being an unpleasant feeling to one that is fentanyl very useful in the out-of-hospital setting. less noxious. Knowing if a drug produces an equianalgesic effect simi- Such notables as Florence Nightingale used opiates for lar to morphine allows Paramedics to understand the impact of their therapeutic benefi t. During one of her own illnesses she an alternative analgesic compared to morphine (Table 31-2). stated that the “curious little new fangled operation of putting Weaker derivatives of opiates (such as propoxyphene, a opium under the skin” gave her relief from her discomfort. spinoff of methadone) are often combined with aspirin or acet- With the advent of the hypodermic needle in the 1950s, the aminophen for an enhanced effect. When combined, two anal- future of opiates was ensured. Opiates have become a main- gesics tend to potentiate one another, allowing for smaller doses stay analgesic.28 of each with the effect of giving a greater dose of one of them. 690 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Table 31-2 Dose Equivalency of Common retention, which in turn promotes cerebral vasodilatation and Opiates* subsequent increased intracranial pressure (ICP). Drug Dose Opiates also complicate the neurological examination of the patient with head injuries by producing miosis (pinpoint Morphine 10 mg pupils). As a general rule, opiate use is avoided in patients Methadone 10 mg with potential head injuries. Meperidine 75 mg Occasionally, opiates (particularly morphine) will cause the Codeine 60 mg release of histamine from mast cells. The result is anaphylactoid Hydromorphone 1.5 mg reaction complete with urticaria (hives), pruritus (itching), and Fentanyl 25 mcg facial edema but is not a true anaphylactic reaction. Treatment usually involves symptomatic care using Benadryl. *All medications are given IM. Transdermal Street Smart A number of transdermal administration methods have been created to administer opioids long-term. These transdermal Small amounts of codeine are found, along with systems often use a gelled alcohol as a vehicle; the body’s opium, in the common Poppy. They are both plant heat will melt the gel so that absorption will occur. Properly applied, the patch should be placed on smooth (hairless) and alkaloids that are chemically related. Therefore, it intact skin that is clear of soaps, oils, and lotions that might is not uncommon for a patient who has an allergy to impede absorption. Fevers (greater than 102°F) as well as codeine to have a cross-allergy to morphine. application of heating pads and electric blankets can increase the absorption of the opiate, leading to toxicity. Transdermal patches should also be removed and disposed of properly. Application of new patches without removal of used patches Synthetic Opiates may result in toxicity. Pharmacists continue to try to create synthetic opiates that do not have morphine’s undesirable effects. Methadone, a syn- Continuous Infusion thetic opiate, is equianalgesic to morphine and is useful in Unremitting pain from cancer, for example, requires a the treatment of narcotic addiction. It has many of the same constant administration of opiates in order to obtain, then effects as morphine. However, methadone’s single greatest sustain, the analgesia. Special patient-controlled analge- advantage may be that it can be taken orally, with the same sia (PCA) infusion pumps provide the patient with the effect, avoiding the dangers inherent in the use of needles. ability to control the amount of analgesia administered For this reason, and because methadone has a long half-life, without interruption. methadone is used in heroin detoxifi cation programs. Meperidine, another synthetic opiate, is an effective anal- Precautions gesic but requires large oral doses to become dose-equivalent While morphine has poor lipid solubility, making passage to morphine; 310 mg PO equals 75 mg IM, which is equian- across the blood-brain barrier less likely, other opiates (such algesic to 10 mg morphine. At these higher doses, meperi- as fentanyl) rapidly pass across both the blood-brain barrier dine has too many complications, including potentially toxic as well as the placental barrier. For this reason, caution must buildup of metabolites, to make it useful. Meperidine is used be advised when giving any opiate to ensure that it does not in smaller doses to treat moderate to mild pain. pass directly into an unborn infant, depressing the infant’s On the positive side, Meperidine is unlikely to cause mast respiratory drive. cells to release histamine and produce the pseudo- allergic Concerns related to adverse effects of opiate adminis- reaction seen with morphine. Meperidine also has an atropine- tration are directly related to the predictable effects of the like quality that causes pupil dilation, not constriction, which opiates in the body. The most notorious side effect of opi- is unlike the other opiates. ates is respiratory depression. Patients who have pre-existing pulmonary disease, such as emphysema or cor pulmonale, Opiate Antagonists are at risk for atypical respiratory depression and even risk Opiate antagonists can also induce acute opiate withdrawal. respiratory arrest with standard therapeutic doses. Cases of Opiate antagonists, like naloxone, dislodge opiates from the death have been attributed to

opiates given in routine doses in opiate receptors. Undesired effects of opiate administration, these patient populations. such as respiratory depression, are immediately reversed, as Respiratory depression induced by opiates can also have well as the euphoric feeling that some addicts crave. Unsus- deleterious effects upon the patient with a traumatic brain pecting Paramedics have been assaulted by heroin addicts injury. Slowed respirations directly translate to carbon dioxide because the provider “ruined the high.” Pharmacological Therapeutics for Medical Emergencies 691 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Non-Opioid Analgesics Street Smart Federal and state restrictions on opiate use, including manda- tory triple prescriptions, have made acquiring opiates for pain The hallmark of opiate intoxication is the pinpoint relief diffi cult. Patients with minor to moderate pain often do pupils (miosis). The presence of miosis is suggestive not seek out medical assistance but rather self-treat and avoid the expense of medical care that does not include opiates. of high enough opiate levels to induce respiratory This way of thinking has led to a boom in nonprescription depression. Patients taking meperidine may not non-opioid analgesics sales. demonstrate miosis and the unsuspecting Paramedic This group of analgesics is also referred to as “non- might not be prepared for the respiratory depression narcotic,” leading to the assumption that these drugs are not addictive. While strictly correct (non-opioid analgesics gen- that ensues.29 erally do not lead to physiological addiction), many of these analgesics are habit-forming. Unsupervised chronic use of these drugs can lead to long-term complications, including organ-specifi c toxicity. Street Smart Salicylates Aspirin (ASA) is the prototypical non-opioid analgesic. Opiates, such as meperidine and morphine, can Brought to the market in 1897 by the Bayer pharmaceuti- have unpredictable interactions with MAO inhibitors. cal company,32 it remains the world’s most popular medica- Symptoms can include excitation, fever, seizures, tion. However, the central ingredient (salicylate) is found in many other over-the-counter drugs (e.g., Oil of Winter- and profound hypertension leading to hypertensive green). Salicylates (from the Latin salix, meaning willow) crisis.30 Opiates should be avoided in patients who are have three major pharmaceutical actions: analgesia, anti- receiving—or whom have received—MAO inhibitors in pyretic, and antiplatelet. the past three weeks. In small doses (less than 1,000 mg), salicylate com- pounds are effective for the relief of mild to moderate pain from muscular strains, joint discomfort, headache, and the like. The pain-relieving action of salicylates is primarily at the peripheral site of infl ammation, not centrally in the brain Naloxone is typically administered parenterally, either as is the case with narcotics. intravenously or intramuscularly. Recently, a nasal form of naloxone has been marketed, which would avoid the use of intravenous needles in this HIV-prone population. Infl ammatory Process The onset of naloxone is one to two minutes when admin- Whether caused by a break in the skin (infection), oxygen istered intravenously and can last for up to one and one-half deprivation (hypoxia), chemical irritation (inhalation of gas), hours. Predictable side effects of opiate antagonists (such as or trauma (mechanical injury), the body initiates an infl am- naloxone) include tachycardia, hypertension, and vomiting. matory response at the site of the injury. The infl ammatory The half-life of most opiates is at least twice as long (four to response is an exact process that begins immediately and fi ve hours in most cases), requiring repeat doses of naloxone includes nonspecifi c defenses, phagocytes, mast cells that in order to obliterate the effects of the opiate. release histamine (causing vasodilatation), macrophages that release lysosomal enzymes, and specifi c responses such as antibodies. The activities of these various body defenses culminate Street Smart in the signs of local infl ammation typically manifested by redness and swelling, histamine-induced vasodilation, the accumulation of dead leukocytes and bacteria as pus, and Hurried administration of naloxone, a narcotic the release of pyrogens (fever-producing chemicals) from antagonist, to a depressed newborn of a heroin the leukocytes. addicted mother, or a mother on methadone Prostaglandins, unsaturated fatty acids, are pivotal in this response. Prostaglandins increase postcapillary venule per- maintenance, can precipitate a seizure in the meability as well as smooth muscle contraction. More impor- newborn.31 tantly, prostaglandins produce the pain, either visceral or somatic, that is characteristic of an infl ammatory response. 692 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Inhibition of prostaglandin production therefore reduces or While not a toxicity per se, aspirin is not given to children eliminates the pain. Salicylates work by bonding to an enzyme because of the association between aspirin given to children called cyclooxygenase, which would normally bind with the with a fever of unknown origin (FUO) and Reye’s syndrome, fatty acids to produce prostaglandins.33 Salicylates thus inter- an acute encephalopathy. Reye’s syndrome is an abnormal rupt the production of pain-producing prostaglandins. degeneration of fat, especially in the viscera, that can also Without prostaglandins, prostaglandin derivatives— lead to acute encephalopathy. including thromboxane A2 (TxA2)—cannot be produced. TxA2 causes local vasoconstriction and encourages the degranulation of platelets, the fi rst step in the coagulation cascade (sometimes called production of the platelet plug). Street Smart Thus, salicylates are also anti-platelet drugs. As such, sali- cylates (specifi cally aspirin) have seen a great deal of use in Aspirin in routine doses reduces fever. Aspirin in preventing the formation of thrombus that can lead to acute myocardial infarction or cerebral vascular accident. large doses can actually induce a paradoxical rise in The third infl ammatory response, fever, is also affected temperature. Well-meaning parents can overdose a by salicylates. A febrile response is caused when pyrogens child on aspirin, see the child’s temperature rise, and are released from the site of the infl ammation and circulate then mistakenly administer more aspirin, thinking to the hypothalamus. These pyrogens then affect the hypo- thalamus and the body’s temperature is changed. Salicylates they are treating the fever. are thought to reset the body’s temperature set-point back to normal by interfering with circulating pyrogens. Salicylate Toxicity Nonsteroidal Anti-Infl ammatory Drugs An allergy to aspirin is a relatively common drug allergy, The nonsteroidal anti-infl ammatory drugs (NSAIDs), com- one whose presence is complicated by the large number monly referred to as aspirin substitutes, have found increas- of salicylate-containing compounds in drugs and over-the- ing popularity for several reasons: aspirin allergies, pediatric counter medications. Caution is advised whenever giving restrictions regarding aspirin use, and unwanted salicylate any drug to determine if an allergy exists, particularly an side effects (Table 31-3). The earliest non-salicylate analge- aspirin allergy. Salicylates have also been known to induce sics were the para-aminophenols (short-name anilines) which an asthma attack in prone patients, as shown in the previous included acetaminophen (APAP). Despite the difference in discussion of aspirin-induced asthma. Paramedics should formulation, the mechanism of action for these NSAIDs is also be particularly aware of the potential for hypoglyce- the same as for salicyclates (interference with the enzyme mia (particularly for children) that exists during a salicylate cyclooxygenase), which in turn inhibits prostaglandin pro- overdose. duction and thromboxane. Intentional or non-intentional overdose of salicylates A notable difference between the two products (NSAIDs creates a mixed respiratory alkalosis secondary to increased and aspirin) is that aspirin irreversibly interferes with platelet carbon dioxide production and metabolic acidosis due to the function for the life of the platelet, whereas most NSAIDs do increased metabolism and increased metabolic acid produc- not interfere with platelet function at all. tion.34 Treatment focuses on routine gut decontamination as well as reversal of the acid–base disorder.35 If the patient expe- Acetaminophen Toxicity riences spasms of the muscles (titanic spasm) secondary to The increasing popularity of any drug often results in cases of the acidosis, calcium gluconate is effective for offering symp- toxicity. An overdose of aspirin is usually quite evident, as the tomatic relief while the underlying acidosis is corrected. patient goes into a metabolic acidosis. His or her respirations Table 31-3 NSAIDs Class Drug Onset Half-Life Dose Acetic acids Diclofenac 31 min 2 hours 50 mg PO Indomethacin 31 min 4 hours 25/50 mg PO Ketorolac 10 min 4 hours 30 mg IV Oxicams Piroxicam 2 to 4 hrs 24 hours 20 to 40 mg Propionic acids Ibuprofen 31 min 2 hours 310 to 800 mg Naproxen 60 min 12 hours 250 to 500 mg Pharmacological Therapeutics for Medical Emergencies 693 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. these cases would only serve to mask the underlying pathol- Street Smart ogy and put the patient at risk for more serious and poten- tially life-threatening complications. For example, convulsions secondary to eclampsia (tox- Originally, many NSAIDs were FDA approved emia of pregnancy) can be effectively treated with either prescription medicines. Manufacturers of these FDA diazepam or phenytoin. However, current evidence suggests prescription medicines requested (and have received) that magnesium sulfate is the drug of choice in these cases permission to sell some of these NSAIDs as over- because it treats the underlying pathophysiology.37 That said, a distinction must be made between the woman with eclamp- the-counter (OTC) medications. The only difference sia who is seizing and the woman with a seizure history who between prescription NSAIDs and OTC NSAIDs is the also has pre-eclampsia. In the fi rst case, magnesium sulfate dose of the drug. The assumption is that the patient would be preferred, whereas in the latter case diazepam would be preferred. using an OTC will follow the package instructions to While the possible teratogenic effects of seizure medica- avoid the side effects and complications associated tion must be considered before prophylactic use is advised, a with larger doses. reoccurrence of a seizure can also produce fetal anoxia. For the patient with a previous diagnosis of epilepsy (recurrent seizures without known cause), the most likely cause of another seizure is subtherapeutic levels of anticon- would become rapid (tachypnea) and the patient would vulsant medication. For whatever reason (e.g., sudden with- become outwardly symptomatic. drawal or poor compliance), the drug level in the plasma In the case of many NSAIDs, there are no immedi- drops below the therapeutic level and the patient experiences ate outward manifestations of toxicity. Acetaminophen, for a breakthrough seizure. Regardless of this fact, other etiolo- example, is highly hepatoxic.36 Undiscovered acetaminophen gies for seizure cannot be ignored and must be ruled out. toxicity can cause permanent liver damage within three days While anticonvulsant medications can help a patient of the overdose. return to the activities of a normal life (e.g., driving a car), these drugs do not cure epilepsy. They only control the num- Convulsions ber and severity of each seizure. However, four out of fi ve patients with epilepsy can have their seizures controlled A generalized convulsion, the outward manifestation of a with medications. seizure, is a series of whole body contractions (tonic), then repetitive contractions (clonic), that are immediately pre- Anticonvulsant Medication ceded by a loss of consciousness. The underlying seizure is Over the centuries, seizures have been variously described the result of random and disorganized neuronal discharge as the work of evil spirits, the patient’s soul wrestling with within the brain, particularly across the motor strip of the the devil, and as a rabid infection, after witnessing the same cerebral cortex, anterior thalamus, and basal ganglia. frothing of the mouth

as seen with patients who were infected The origin of the convulsion can be from an abnormal with rabies. Not until the works of Jean-Martin Charcot, in focus in the brain that is triggered by hypoxia, hypoglycemia, the mid-1900s, was the grands paroxysmes considered a pos- hyperthermia, and other stimuli. It can also be triggered by sible symptom of a greater pathology—the result of poten- extra-cranial sources (such as toxic inhalations, electrolyte tially curable organic lesions.28 imbalances, or drugs) or iatrogenic sources, secondary to In the past, treatment for epilepsy often started with a subtherapeutic anticonvulsant levels. barbiturate. Phenobarbital was frequently chosen because of The chaotic brain activity during a seizure is somewhat its margin of safety (discussed earlier). Subsequently, newer, analogous of the chaotic myocardial activity during ventricu- more effective medications have largely replaced phenobar- lar fi brillation—purposeless and potentially life-threatening. bital for the treatment of epilepsy. However, phenobarbital Regardless of the cause, the patient lapses out of con- still sees use in the emergency setting, primarily where respi- sciousness and is at risk for injury secondary to falls or status ratory depression can be managed expertly and for the few epilepticus, a condition of unremitting convulsions. cases of uncertain eclampsia and status epilepticus. The therapeutic goal of anticonvulsant medications is to raise the seizure threshold (by depressing the epileptic focus Mechanism of Action within the brain) without altering the patient’s mental status and CNS functioning. Most anticonvulsants, including phenobarbital, negatively In every case, regardless of prior history, Paramedics infl uence the action potential of the neuron and thus inhibit should attempt to identify and treat potentially reversible spurious discharges. The majority of anticonvulsants act as causes of convulsions, such as hypoxia, hypoglycemia, or sodium channel-blockers, a mechanism that is similar to the hyperthermia. Anticonvulsant medications administered in mechanism of a Class IB antidysrhythmic medication. 694 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Barbiturates Hydantoins and Pregnancy Barbiturates, including phenobarbital, are a class of CNS Women with a history of epilepsy who become pregnant are depressants that have seen second service as anticonvul- often taken off of hydantoins to eliminate the risk of fetal sants. One advantage of barbiturates is the wide variety hydantoin syndrome (FHS). Hydantoin use during preg- of delivery methods (PO, IV, IM) as well as the various nancy can generate birth defects such as cleft lip, cleft palate, duration of actions. and congenital heart anomalies.40,41 Primidone, whose active metabolite is phenobarbital, is If left untreated, approximately 50% of pregnant women seeing greater use for control of seizures and is often used with a prior seizure history will experience at least one sei- in combination with carbamazepine and phenytoin. By being zure during their pregnancy.42 Seizure during a pregnancy used together, these drugs permit lower doses of each. can induce fetal anoxia, which can result in congenital birth defects including mental retardation. Hydantoins The quandary lies in whether to prophylactically treat the seizure disorder, and potentially risk FHS, or risk a seizure One of the oldest and most widely used anticonvulsants, and fetal anoxia. In most instances, alternative medications phenytoin, belongs to the class of hydantoins. As a class, are explored. If these are ineffective, then the lowest possible these drugs are chemically related to barbiturates and act to dose of hydantoin is prescribed. decrease the infl ux of sodium (i.e., sodium channel-blockers), thereby decreasing neuronal excitability. Carbamazepine Fosphenytoin, another hydantoin, is the prodrug to phe- Carbamazepine has a mechanism of action that is similar to nytoin. Fosphenytoin has a rapid onset of action (peaking in hydantoins but is chemically similar to the tricyclic antide- less than six minutes), can be administered intravenously at a pressants. Carbamazepine is used, with good effect, to control rate three times faster than phenytoin (without cardiac com- a large variety of seizures including partial seizures with com- plications), and causes less burning at the IV site.38 Cumula- plex symptoms, as well as generalized tonic-clonic seizures. tively, these advantages make fosphenytoin desirable as an Carbamazepine is slow to absorb. It is not unusual for the emergency medication. drug to take a month or more to obtain therapeutic levels in the blood. Despite this obstacle, carbamazepine is the drug Hydantoin Toxicity of choice for many pediatric patients because of its low inci- Maintaining a serum plasma level of hydantoins that is dence of side effects. Concurrent administration of erythro- t herapeutic—and not toxic—is complicated by the distribu- mycin, an antibiotic occasionally prescribed to children, can tion and biotransformation of the drug. Hydantoins quickly lower circulating plasma levels of carbamazepine in the child become protein-bound (primarily to blood albumin) while with epilepsy and result in breakthrough seizures. in circulation. Thus, a large percentage of the drug is phar- Carbamazepine Toxicity macologically unavailable. Only when all available albumin becomes saturated are suffi cient plasma levels of free drug Simultaneous administration of isoniazid (another antibiotic available for its intended therapeutic effect. used to treat tuberculosis) and propoxyphene (an analgesic) Compounding this diffi culty is the drug’s biotransfor- can cause an increase in blood serum levels of carbamazepine mation. The liver’s enzymatic system, the cytochrome P-450 to the point of near-lethal toxicity. system, is very effective in reducing hydantoins to inactive Co-administration of carbamazepine with an MAO metabolites. However, hepatic metabolism has limits. Once inhibitor (an antidepressant) can also cause elevated tem- these limits are reached, then more free drug is available. perature (hyperpyrexia), elevated blood pressure (to hyper- Therefore, to reach desired therapeutic levels of hydantoin, tensive crisis levels), and, paradoxically, seizures leading to dosing must take into account both the volume of blood pro- status epilepticus. teins as well as hepatic biotransformation. Overcoming these Succinimides two impediments, even with small incremental increases in hydantoin dose, can result in marked, or near-toxic, eleva- Succinimides, as a class of anticonvulsant medication, raise tions in serum drug levels. the seizure threshold and suppress nerve conduction in the The patient who is toxic on hydantoin will present with motor cortex, resulting in good seizure control. Ethosuxim- an ataxia (a disequilibrium in walk that resembles a drunk- ide, an example of a succinimide, is used to treat pediatric ard’s stagger) and a nystagamus (a fi ne tremble of the eye absence seizures. when holding a lateral gaze).39 Unsuspecting Paramedics may incorrectly deduce that the patient is intoxicated on alcohol. Valproic Acid Hydantoins, in toxic doses, have signifi cant cardiac effects, Valproic acid and divalproex have similar actions (increasing similar to Class IB antidysrhythmic drugs. Left untreated, levels of the inhibitory neurotransmitter GABA within the these cardiotoxic effects can lead to cardiovascular collapse brain) and are used alone or in combination with other anti- and death. convulsants to treat absence seizures. Pharmacological Therapeutics for Medical Emergencies 695 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Valproic acid is also useful in the emergent treatment of common neurological disorder.43 The onset of Parkinson’s status epilepticus that is unresponsive to standard treatments. disease can start as early as 40 years of age and is slightly more prevalent in males. While Parkinson’s disease itself Benzodiazepines is not a medical emergency, the effects of the disease (like Benzodiazepines, discussed earlier, are also useful as anti- falls, which often result from dyskinesia) create emergency convulsants. Paramedics, when confronted with a patient in situations. status epilepticus, can administer a benzodiazepine (such as diazepam or the short-acting midazolam) for control of the Pathophysiology seizure. In those cases, Paramedics must be prepared to man- As a person develops Parkinson’s disease, the number of age respiratory depression secondary to the benzodiazepine. do paminergic receptors in the brain is reduced (Figure 31-1). The gradual loss of these receptors results in a progressive Parkinson’s Disease deterioration of brain function. Dopaminergic receptors are Parkinson’s disease has an insidious onset, starting with barely abundant in the substantia nigra, a portion of the central ner- perceptible rhythmic tremors and progressing to gross motor vous system’s extrapyramidal motor system responsible for dysfunction. In an advanced stage, the patient with Parkin- muscle coordination and movement. son’s disease exhibits extremely slow (bradykinesia) or dif- Normally, the dopaminergic receptors produce an inhibi- fi cult (dyskinesia) movement. For example, if a patient with tory effect upon the extrapyramidal motor system. In the Parkinson’s disease is gently pushed, the patient’s muscles absence of dopaminergic receptors, the cholinergic receptors may not be able to respond quickly enough to stop a fall. take dominance by stimulating the extrapyramidal motor. The The combination of loss of airway control, manifested clinical manifestations of Parkinson’s disease are the result of by drooling and slurred speech, as well as a blank mask-like this imbalance between dopaminergic stimulation and cho- stare, makes the patient with Parkinson’s disease appear dull linergic stimulation. Classic symptoms of Parkinson’s disease and dimwitted. Yet, Parkinson’s disease affects the intellec- include muscle rigidity, resting tremors, a forward leaning tual capacity of only 40% of the patient population affl icted posture, and a shuffl ing gait. with Parkinson’s disease. However, the combination of Drugs That Are Used to Treat events just described can often produce severe depression in this patient population, leaving an appearance of dwindling Parkinson’s Disease intellectual capacity. Treatment of Parkinson’s disease focuses on either blocking Approximately 150 in 100,000 people over age 65 the cholinergic receptors (suppressing the effects of acetylcho- will develop Parkinson’s disease, making it the fourth most line) or increasing the level of dopamine receptor stimulation. Cholinergic neuron Acetylcholine Caudate nucleus To muscles Akinesia Normal function Hyperkinesia Feedback neuron Putamen Caudate nucleus GABA Dopaminergic Globus Thalamus neuron pallidus Red Substantia nucleus nigra Substantia nigra Figure 31-1 Parkinson’s disease. 696 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. The quintessential cholinergic blocker is atropine, the bella maintains those mundane vegetative functions of life, while donna alkaloid extracted from the nightshade plant. Atropine the sympathetic nervous system stands by, ready to react at was used for years to treat Parkinson’s disease. a moment’s notice to any threat to that life. Similarly, the More recently, newer synthetic cholinergic blockers, endocrine system, via its arrangement of chemical messen- such as benztropine, have been used with better effect. These gers, helps to maintain an optimal internal environment for cholinergic antagonists decrease dyskinesia in nearly 50% of metabolism while the nervous system is ready to respond to patients suffering from Parkinson’s disease. the ever changing external conditions. The goal in both cases Currently, treatment of Parkinson’s disease is focusing is identical—to maintain a balance (i.e., homeostasis) within more on how to increase dopaminergic receptor stimulation the body and life. than on blocking cholinergic receptors. Means to achieve The chemical messengers that stimulate the body’s this goal include administering drugs that increase dopamine organs and help to maintain the body’s internal environment levels (such as levodopa) or stimulating release of dopamine (its milieu) are called hormones (from the Greek meaning from neuronal storage vesicles (e.g., amantadine). “to arouse”). Hormones are produced and excreted from Alternatively, levels of dopaminergic receptor activity can endocrine glands located in various locations within the body. be increased, not by inducing the body to produce or release The amount of hormone in the bloodstream is a function of a more dopamine, but by using dopamine agonists. Examples

feedback mechanism, a mechanism that monitors and alters of dopamine agonists include bromocriptine, a plant alkaloid, the amount of hormone released. and pramipexole. The most common feedback mechanism is the negative Finally, dopamine levels in the neurosynapse can be feedback loop. A negative feedback loop occurs when increas- increased by decreasing dopamine destruction by mono amine ing levels of a hormone stop the secretion of more hormone. oxidase during uptake. A monoamine oxidase inhibitor, such An exception to hormonal control by feedback mechanism as selegiline, is often given together with levodopa. The is seen when the sympathetic nervous system stimulates the combination of drugs permits lower doses of each, thereby release of epinephrine from the adrenal medulla (an endo- decreasing undesirable side effects while still achieving the crine gland) during stress. This action would be classifi ed as same therapeutic goal. neuronal control. Once a hormone is released into the blood, it circulates Precautions until it is attracted to a target cell with the correct receptor (a Two types of monoamine oxidase exist in the body: type A “key in lock” concept). When linked together, the hormone and type B. MAO inhibitors used to treat Parkinson’s disease can either enhance the cell’s function (a direct effect) or it can primarily affect monoamine oxidase B. Inappropriate admin- facilitate an aspect of the cell’s function. For example, insulin istration of other MAO inhibitors, along with levodopa, can (a hormone) attaches to insulin receptors, which then permit precipitate profound hypertension or hypertensive crisis. the passage of glucose into the cell. Hormones and Pharmacy The hormone’s impact, at the cellular level, is a function of the amount of hormone in the bloodstream and/or the number Street Smart of receptors on a cell. In the fi rst case, if there is a hormone defi cit, as is the case in diabetes mellitus, then supplemental Administration of meperidine to patients on MAO hormone (e.g., insulin) can be administered. inhibitors can cause severe reactions, including When a larger than physiological dose of hormone is administered, there can also be a new or different effect, a profound hypertension, respiratory depression, pharmacological effect. An example of this pharmacologi- hyperpyrexia, and seizures. Alternatively, cal effect is when antidiuretic hormone (ADH), also called administration of morphine is less likely to produce vasopressin, is given in larger than physiologic doses. When these unwanted side effects. that happens, it induces a potent vasoconstrictor effect upon the blood vessels.44 Alternatively, there can be an increase in the number of receptors on the cell, as a result of low hormone lev- els, making the cell more sensitive to the available hor- Drugs That Affect mone. The converse is also true (i.e., there can be fewer the Endocrine System receptors). The change in the number of cell receptors can either increase (called upregulation) or decrease (called The association of the endocrine system and the nervous downregulation) according to hormone levels. In certain system is somewhat analogous to the relationship between pathological conditions it may be necessary to block these the parasympathetic and the sympathetic nervous system. hormone receptors to moderate the hormone’s effect upon The parasympathetic nervous system, via its vagus nerve, the cell. Pharmacological Therapeutics for Medical Emergencies 697 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Diabetes Insulin Type 1 diabetes is characterized by a total loss of insu- Insulin combines with receptors in the cell wall to permit the lin production, making necessary life-long subcutaneous passage of glucose into the cell. This in effect lowers the blood injections of insulin. However, the vast majority of patients sugar in the bloodstream. Insulin also stimulates the storage with diabetes, more than 80%, continue to produce some of excess glucose in the liver in the form of glycogen. insulin. These patients produce insuffi cient quantities of Simultaneously, insulin inhibits the release of free fatty insulin or have an increased resistance to the insulin, and acids. These fatty acids would normally be excreted when- thus are termed type 2 diabetics. The most common cause of ever glucagon is present. (Glucagon stimulates the use of fat type 2 diabetes is obesity; the hallmark of obesity- induced for energy in a process called lipolysis.) diabetes is insulin resistance (a case of either downgrading Since insulin is a protein, it cannot be taken orally as insulin receptors or having an ineffective insulin/receptor stomach acids would immediately break it down into inert effect). materials. Thus, insulin must be given parenterally, usually The fi rst level treatment for many of these patients with via subcutaneous injection, into the peripheral capillary bed type 2, or non-insulin dependent diabetes mellitus (NIDDM) where it can be absorbed into the central circulation. It can is weight control through diet and exercise. Failing this, the also be given intravenously. patient must then resort to an alternative therapeutic strategy— Early insulin was obtained from animals, such as pigs either insulin injections or the use of hypoglycemic agents. and cows. In some cases, patients developed an allergy to the pork or beef insulin. Currently, insulin is bio-engineered and Drugs That Are Used is identical to human insulin, thereby preventing any allergy to Treat Diabetes to insulin. Insulin’s onset and duration of action can be altered Diabetes mellitus is not a single disease. More correctly, dia- by mixing the insulin with other materials such as zinc. betes is a group of syndromes of varying etiologies that have Paramedics should be aware of these other insulin prepara- a similar presentation: increased blood glucose. Even seem- tions, especially the time of onset and peak effect, to be ingly minor alterations in blood glucose can have a dramatic able to anticipate periods of hypoglycemia following an impact on some patients. These changes in blood glucose lev- insulin overdose. els are the source of many EMS calls for assistance. The most rapid-acting insulin is synthetically pre- Blood glucose levels are maintained within a physi- pared insulin that is part of a zinc salt. Rapid-acting regu- ologic range by two hormones produced in the pancreas. lar insulin lowers blood sugar within minutes when given The first hormone, insulin, is produced in the beta cells intravenously. within the islets of Langerhans of the pancreas. It low- The intermediate-acting insulin preparations use ers blood glucose by facilitating passage of blood glucose protamine to prolong their duration of action. Protamine, a into the surrounding cells and tissues. When the level peptide, makes insulin a less soluble complex, slowing absorp- of blood glucose rises, then the pancreas produces more tion and increasing its duration of action. Intermediate-acting insulin. When the level of blood glucose drops, then the insulin, or neutral protamine Hagedorn (NPH), is never given alpha cells within the islets of Langerhans release glu- intravenously. cagon (a hormone that increases blood glucose levels). Long-acting insulin preparations are the result of vari- Together, these two hormones help to maintain a blood ous processing techniques and result in insulin that has a glucose level within a physiological range sufficient for delayed onset of action as well as a prolonged duration of the body’s metabolic needs. action (Figure 31-2). For most patients, a relatively stable blood glucose level Drugs That Are Used to Treat would be desirable and the option of mixing various insulins Diabetic Emergencies (rapid, intermediate, and long-acting) to attain a near constant Diabetic emergencies can be neatly divided into problems of blood glucose level would be reasonable. With this thought low blood sugar (hypoglycemia) and high blood sugar (hyper- in mind, Lente insulin, a mixture of 30% semilente insulin (a glycemia). Hypoglycemia often has a more dramatic presen- rapid-acting form of regular insulin) and 70% ultralente insu- tation, such as sudden unconsciousness or convulsions. For lin (an extended-insulin zinc suspension that is poorly soluble) this reason, it is a common source of calls for EMS. was created. Lente insulin helps to avoid some of the tendency Diabetic hypoglycemia can be the result of either toward hypoglycemia experienced by some diabetic patients. increased insulin levels, via self-administration or pancre- As noted earlier, Paramedics should be aware of the atic production, or insuffi cient food intake in relation to peak effect of the various insulins. In cases where the patient insulin levels. To understand the etiology of these hypogly- has mixed insulin and subsequently has a period of hypo- cemic periods, it is necessary to understand the action of the glycemia, the patient can expect to have another episode of hormone insulin. hypoglycemia. 698 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Profiles of Human Insulins and Analogues when accompanied by fever; and trauma—can lead the dia- betic patient to have an unexpected episode of hypoglycemia. Alternatively, changes in eating habits or activity patterns—or new medications such as MAO inhibitors, sulfonamides, sali- cylates, beta-blockers, and ethanol (EtOH)—can cause inad- vertent hypoglycemia.48 The clear majority of hypoglycemia cases in patients with type 1 diabetes are related to changes in insulin regime. When the patient becomes hypoglycemic, another 0 2 4 6 8 10 12 14 16 18 20 22 24 hormone (epinephrine) is released. Epinephrine normally Hours inhibits insulin secretion, thereby increasing blood glucose levels in an emergency. Released by sympathetic stimula- Aspart, lispra (4 to 6 hours) tion of the adrenal medulla, epinephrine is responsible for Regular (8 to 10 hours) the majority of the symptoms present during a hypogly- NPH (12 to 20 hours) cemic episode, such as tachycardia, tremors, diaphoresis, Glargine (20 to 26 hours) headache, and hypertension. Ultralente (18 to 24 hours) Treatment of Hypoglycemia Figure 31-2 Onset of action of insulin preparations. Treatment of hypoglycemia is simple: Replace the glucose until adequate levels of blood glucose are available to resume Insulin and Hyperkalemia normal metabolism. Methods of glucose administration include oral paste as well as intravenous administration. Typ- Insulin is a negatively charged amino acid. As such, insulin ically, 25 grams of dextrose is administered intravenously, binds to positively charged electrolytes, such as potassium. either as 500 cc of 5% dextrose in sterile water (D5W) or Elevated potassium levels (hyperkalemia) lead to signifi cant 50 cc of 50% dextrose solution. dysrhythmias and can be life-threatening. Intravenous admin- The effects of intravenous administration of 50% dex- istration of insulin can be used to treat hyperkalemia because it trose upon hypoglycemia is immediate but not without its binds the potassium to the insulin. When the insulin attaches to complications. Concentrated dextrose is hypertonic. There- the cell, it drives the potassium into the cell with it and out of fore, administration through a misplaced intravenous line the circulation.45-47 This technique is very effective for lowering and subsequent subcutaneous infi ltration can lead to severe serum potassium levels, but caution must be exercised to pre- tissue necrosis. vent inadvertent hypoglycemia. Typically a glucose-containing solution is concomitantly administered along with the insulin. Street Smart Street Smart A hypoglycemic patient can present in the fi eld Diabetes is a leading cause of blindness, which with facial droop, confusion, and slurring of words. occurs because of diabetic retinopathy. Patients with This presentation may be mistaken for a stroke diabetes, who are unable to see or unable to see and grave complications may occur subsequent clearly, may unintentionally overdose themselves to this misdiagnosis.49 Similarly, a patient with with insulin. Aids for the blind (e.g., guide dogs) stroke symptoms should not be assumed to have should raise the Paramedic’s index of suspicion that hypoglycemia. Inappropriate administration of the cause of the medical emergency may be visual concentrated dextrose to a stroke patient with impairment that may be diabetes related. a normal blood sugar level can induce changes

Hypoglycemia secondary to the osmotic effect of the concentrated dextrose. Dextrose should only be administered Untreated hypoglycemia, sometimes referred to as insu- lin shock, can lead to coma and even death. A number of to those patients with evidence of hypoglycemia factors—such as the stress of surgery; infections, especially (e.g., a low glucose meter reading). Pharmacological Therapeutics for Medical Emergencies 699 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Plasma insulin levels An alternative treatment for hypoglycemia, when intra- (zona fasciculata) produces the glucocorticoids, including the venous administration of glucose is not possible, is intra- principal glucocorticoid cortisone. The innermost zone (zona muscular injection of glucagon. Glucagon, which is naturally reticularis) produces the adrenal androgens and estrogen. secreted by the alpha cells in the pancreas, raises the blood The glucocorticoids help to regulate metabolism of car- glucose level by liberating glucose from glycogen stores in bohydrates, increase blood glucose by helping to convert the liver. By defi nition, for glucagon to work there must be glycogen to glucose, antagonize insulin, and help create glu- adequate stores of glycogen in the liver. Patients with liver cose from amino acids by a process of protein catabolism disease or those who are chronically malnourished may not (gluconeogenesis). have glycogen stores, thereby rendering glucagon useless. The glucocorticoids also inhibit both the immune system Glucagon’s onset of action is dependent upon its route and the infl ammatory response by suppressing the chemical of administration (15 minutes via IM injection and 31 min- mediators such as prostaglandins, leukotrienes, bradykinin, utes by subcutaneous injection). The delay in onset of action serotonin, and histamine. makes intravenous dextrose administration more desirable. Levels of glucocorticoids rise during periods of stress, providing needed glucose. However, they also lower resis- Oral Hypoglycemia Agents tance to infection during those times. Chief among these naturally occurring glucocorticoids is cortisol. Cortisol secre- The three therapeutic strategies that could potentially increase tion, regulated by the hypothalamus and the anterior pituitary insulin levels include (1) stimulation of the beta cells in the gland via adrenocorticotropic hormone (ACTH) stimulated pancreas to produce more insulin or to reduce glucagon l evels, by low levels of cortisol, travels throughout the body bound (2) suppression of the alpha cells in the pancreas, or (3) an to blood proteins such as albumin. increase in the binding of insulin to receptors on the cells. The sulfonylureas were the fi rst class of drugs that could Synthetic Glucocorticoids produce all three of these desirable mechanisms of action. Paramedics may be called upon to administer steroids in The introduction of sulfonylureas eliminated the need for order to treat severe infl ammatory responses that occur in some patients to inject insulin. Each successive generation severe asthma, including status asthmaticus, acute allergic of sulfonylureas, while not more effective than the previous, reactions, and anaphylactic reactions that are unresponsive have as positive features a longer duration of action as well as to standard treatment. fewer side effects. Treatment with steroids may also be indicated for Other oral hypoglycemia agents include (1) the alpha- gram-negative septic shock.50 Endotoxins released from the glucosidase inhibitors, which delay the digestion and absorp- gram-negative bacteria injure cells and alter the patient’s tion of carbohydrates, permitting subphysiological levels of coagulation. Glucocorticoids suppress many of the chemi- insulin production to suffi ce; and (2) other non-sulfonylurea cal mediators in the coagulation cascade, in addition to pro- agents, such as metformin, which have a similar mechanism tecting cellular membranes. Glucocorticoids also potentiate of action. catecholamines, such as dopamine, increasing their vasocon- The newest class of antihyperglycemia agents lowers strictive activity. insulin resistance, permitting more effective use of the Glucocorticoids are also administered as replacement patient’s own endogenous insulin. These medications stimu- therapy for adrenocortical insuffi ciency (Addison’s disease). late the release of helper proteins from the muscles and fat. Typically, a dose of hydrocortisone, the synthetic equivalent These proteins enhance the cells’ response to insulin by a to naturally occurring cortisol, is given: two thirds in the mechanism entirely different than the sulfonylureas’ mecha- morning and one third in the afternoon, to match the patient’s nism of action. Currently research is on–going for medica- circadian rhythm. tions that can lower insulin resistance, a major cause of type Glucocorticoids can be broken down into three subclas- II diabetes, particularly in the obese patient population. sifi cations according to their duration of action. The short- acting glucocorticoids include hydrocortisone and cortisone (which is converted into hydrocortisone in the body). These Drugs That Are Used to Treat short-acting agents generally have a half-life of about 8 to Adrenal Disorders 12 hours in the tissues. The intermediate-acting glucocorticoids include predni- The paired pyramid-shaped adrenal glands, located just sone and methylprednisolone. They have an average half-life above the kidneys, produce a rich supply of hormones that of 18 to 36 hours in the tissues. are essential to the body’s health. All of these hormones are Dexamethasone, an example of a long-acting steroid, produced from cholesterol and have a common steroid core is occasionally used to treat the edema seen following head (hence the term “steroids”). injury or secondary to a brain tumor.51 Beclomethasone dipro- Dividing the adrenal cortex into three zones, the outer pionate, another example of a long-acting steroid, is available zone (zona glomerulosa) produces the mineralocorticoids, in an aerosol form for long-term use in patients with severe chief among those being aldosterone. The larger middle zone asthma. This aerosol form permits lower doses than would be 700 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. given orally and minimizes some of the undesirable systemic epinephrine can cause paroxysms of hypertension, cause sus- effects of steroids. tained hypertension, induce a hypertensive crisis, and create a “runaway” tachycardia. Occasionally, an episode of hyperten- Precautions sion follows a meal of tyrosine-rich food, red wine, beer, or Administration of glucocorticoids may cause fl uctuating glu- aged cheese. Tyrosine is the precursor of epinephrine. cose levels, as glucocorticoids promote metabolism. Use of Rupture of a pheochromocytoma can literally lead to these steroids may cause hypoglycemia in diabetics and those a systemic fl ood of epinephrine accompanied by profound prone to hypoglycemia. hypertension, severe abdominal pain, and a potentially fatal Glucocorticoids also have some related mineralocorti- hemorrhage. Treatment for a hypertensive emergency includes coid activity. The result is retention of salts and water with intravenous administration of an alpha-blocking agent (e.g., subsequent edema and hypertension that can progress to con- phentolamine) and a beta-blocker (e.g., metoprolol) to con- gestive heart failure in susceptible patients. Long-term use of trol the runaway tachycardia. these steroids can result in iatrogenic Cushing’s syndrome. The patient’s presentation will include a puffy face (Moon Drugs That Are Used to Treat face), acne (early sign), hypertension, weight gain, and an increase in body hair. Ovarian Disorders Patients on steroids become dependent on those steroids, Estrogen and progesterone are the principal sex hormones as levels of naturally produced steroids drop off. Abrupt produced by the ovaries. Created from cholesterol (like the withdrawal of these steroids can lead to acute adrenal insuffi - steroids of the adrenal glands), estrogen and progesterone ebb ciency.52 Tapering doses of the steroid are required for patients and fl ow rhythmically, creating a woman’s menstrual cycle. who are prescribed steroids for longer than two weeks to gen- This continues until pregnancy interrupts the sequence. tly re-establish a natural response from the adrenal gland. Estrogen is primarily responsible for a woman’s sexual development as well as regulation of her menstrual cycle. Mineralocorticoids Besides effects upon the ovaries, estrogen also has metabolic The primary mineralocorticoid, aldosterone, is largely effects. For example, estrogen helps to maintain bone density. responsible for electrolyte and fl uid balance and acts upon the When a woman stops producing estrogen (i.e., menopause), she distal tubules of the kidneys. This steroid primarily conserves is at greater risk of losing bone density (i.e., osteoporosis). sodium, while promoting potassium and hydrogen ion (acid) Estrogen also has a cardioprotective effect. This alters excretion. The production of aldosterone is controlled by the the metabolism of cholesterols, decreases serum levels of renin-angiotensin mechanism, which is activated by sodium low-density lipoproteins and high-density lipoproteins, and and/or blood volume depletion. prevents atherosclerosis. High levels of aldosterone can induce hypokalemia, which can create cardiac irritability manifested as ventricular Estrogen Therapy ectopic beats, as well as a metabolic alkalosis. Estrogen can be used to prevent pregnancy (a contracep- Antiadrenal Medications tive effect) or during menopause at a one fi fth dose. Estro- gen is used during menopause to prevent atrophic vaginitis, Antiadrenal medications suppress adrenal cortical function, vasomotor symptoms (i.e., hot fl ashes), and abnormal uter- resulting in decreased production of these steroids. Used to treat ine bleeding. Post-menopausal women are at greater risk of Cushing’s syndrome as well as adrenal tumors, these medica- osteoporosis. If unchecked, osteoporosis can lead to brittle tions inhibit the enzyme that converts cholesterol into steroids. bones that fracture. (Hip fractures are more common among As these medications also suppress estrogen production these women.) Estrogen replacement therapy can decrease in the adrenals (a hormone thought to be related to breast the risk of osteoporosis. cancer), investigational cancer studies are in progress. Estrogen is also an effective treatment for some estrogen- Adrenal Medulla sensitive metastatic breast cancers. Paradoxically, estrogen slows tumor growth when it normally increases breast devel- At the core of the adrenal glands is the medulla. The adre- opment in those cases. Conversely, some breast cancers are nal medulla produces the catecholamines norepinephrine and estrogen-dependent. These breast cancers are treated with an epinephrine. Secretion of epinephrine from the medulla is anti-estrogen agent, such as tamoxifen, which blocks estro- largely under sympathetic nervous control (i.e., a neurohu- gen receptors in the tumor. moral regulation). Stimulation of the adrenal medulla can High-dose estrogen, or the morning after pill, a.k.a. plan result from hypoglycemia, hypoxia, hypercapnia, nicotine, B, is sometimes used as an emergency contraceptive (e.g., fol- and angiotensin II. lowing rape or contraceptive failure). If administered within While tumors of the adrenal medulla, called a pheochro- 72 hours, high-dose estrogens (such as diethylstilbestrol) can mocytoma, are rare (less than eight cases per million popula- induce menses, eliminating products of conception. Diethyl- tion), they can produce large amounts of epinephrine.53 Excess stilbestrol, therefore, has a pregnancy class of X. Pharmacological Therapeutics for Medical Emergencies 701 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Drugs That Are Used to Treat Street Smart Thyroid Disorders Estrogen in oral contraceptives can induce The thyroid gland (from the Greek word, meaning “shield- thrombophlebitis and thrombosis formation, leading like”) straddles the thyroid cartilage, commonly known as the Adam’s apple, with a thin isthmus in the middle. The fol- to strokes and pulmonary embolism.54 This risk is licles within the two lobes of the gland secrete the hormones increased in women over age 35 and in women who responsible for metabolism. smoke. Pathology of the thyroid gland involves either hyper- or hyposecretion of thyroxine (T4) or triiodothyronine (T3). Hyperthyroidism can be caused by Graves’ disease, thyroid cancer, or a goiter. Hyperthyroidism results in tachycardia, weight loss, nervousness, and exophthalmos (a bulging of Drugs That Are Used to Treat the eyes). If left unchecked, hypersecretion of thyroid hormones Pituitary Disorders can lead

to thyrotoxic crisis (thyroid storm), a condition The pituitary gland is located just inferior to the hypothala- that can lead to death. Thyrotoxic storm’s symptomology mus nestled in the base of the skull. These are connected to includes atrial tachydysrhythmia, cardiogenic shock, and one another by a thin stalk of tissue called the infundibulum. hyperpyrexia secondary to a metabolism that is increased by This pituitary-hypothalamus axis produces a number of hor- as much as 60%. mones that control other glands. Thus, the pituitary is called Strong iodine solutions, such as Lugol’s solution, may the master gland. be administered during a thyrotoxic crisis. The iodine in The pituitary gland can be divided into two portions: the solution inhibits the formation of tyrosine, a precursor anterior and posterior. The posterior portion produces to epinephrine. Alternatively, thioamide derivatives, such as two hormones: antidiuretic hormone (vasopressin) and propylthiouracil, may be used. These agents inhibit thyroid oxytocin. The primary effect of antidiuretic hormone is hormone synthesis, preventing tyrosine production. to control plasma osmolality and maintain intravascular Hyperthyroidism is typically treated with either surgical volume. ADH achieves that goal by affecting the per- removal of the thyroid gland or administration of radioactive meability of the distal tubules of the kidney’s nephron. iodine, which results in the destruction of the thyroid gland. Oxytocin is discussed later in the section on drugs used The patient, like the patient with hypothyroidism, needs life- during pregnancy. long thyroid hormone replacement therapy. Levothyroxine, a synthetic thyroxine, is one of the more common thyroid preparations prescribed for hypothyroid- Vasopressin ism. Poor patient compliance with the prescribed replace- Vasopressin has received widespread attention for its poten- ment therapy can result in hypothyroidism and myxedema. tial role in cardiac arrest. The hormone’s pharmacological Myxedema is characterized by ataxia (drunken staggers), effect (vasoconstriction) may be useful as a fi rst-line therapy lethargy and confusion, headaches, and a non-pitting edema in cardiac arrest, following defi brillation.55–58 of the eyes, hands, and feet. Myxedema also results in edema Vasopressin is also useful in treating diabetes insipidus. of the tongue and laryngeal mucous membranes, making Diabetes insipidus is characterized by a lack of ADH and may speech slurred. The combination of symptoms might lead be caused by basal skull fractures injuring the infundibulum, less informed Paramedics to suspect intoxication. subsequently causing increased intracranial pressure. It could Amiodarone contains large amounts of iodine, approx- also be caused by a brain tumor or subdural hemorrhage that imately 37% by weight, and can induce hyperthyroidism compresses the infundibulum. There are a number of reasons in a small population of susceptible individuals.59,60 The why the pituitary gland would fail, all culminating in a scar- onset of a new atrial tachydysrhythmia is often seen in city of ADH. these patients. Without ADH, immense volumes of dilute urine are excreted (polyuria), upwards of 3 to 18 L a day, and the Drugs That Are Used patient wants to drink large volumes of water (polydipsia). If unchecked, diabetes insipidus can lead to dehydration, hypo- to Treat Anaphalaxis volemia, and shock. Inappropriate responses to allergens (i.e., allergy, autoim- Natural vasopressin, or synthetic derivatives such as munity, and alloimmunity) can be classifi ed jointly as hyper- lypressin, is prescribed to patients suffering from diabe- sensitivities. Hypersensitivities can further be classifi ed as tes insipidus. immediate or delayed. 702 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Paramedics are most concerned about immediate hyper- Ulcer Medicines sensitivity reactions, the most severe being anaphylaxis. Heartburn and the pain of peptic ulcer was formerly believed Untreated anaphylaxis can progress within minutes to a life- to be the result of excessive stomach acid, so medical attention threatening medical emergency. was turned toward reducing or neutralizing that acid. More A classic anaphylaxis is an IgE-mediated reaction. After recently, the pathogen Helicobacter pylori has been impli- exposure to a foreign protein—one that is inhaled, ingested, cated as the causative agent for peptic ulcers and a course or injected—the body’s immune system produces an antigen of antibiotics as its cure. However, there are other causes of specifi c antibody (IgE). The IgE binds to special crystalliz- stomach infl ammation. These include irritants like alcohol or able fragment (Fc) receptors on mast cells. aspirin, which can produce epigastric discomfort. A number When the patient is re-exposed to the allergen, it of medications, many of them over-the-counter medications, causes the Fc receptors on the mast cell surface to cross-link, one are available to help with these disorders. to the other, destroying the mast cell in the process and releas- ing the cell’s contents. This process is called degranulation. The majority of the symptoms of anaphylaxis are related Antacids to the degranulation of mast cells. Chemical mediators Antacids chemically neutralize stomach acid and bring relief released during degranulation include histamine. Histamine to those suffering from heartburn (i.e., gastroesophageal is responsible for the majority of symptoms associated with refl ux disease (GERD)), hiatal hernia, and gastritis. The com- an anaphylactic reaction: bronchoconstriction, increased vas- pounds calcium carbonate, sodium bicarbonate, magnesium cular permeability leading to angioedema, and vasodilation- salt, and aluminum salt are used for this purpose. induced hypotension.61 A concern with many of these medications involves some of their systemic effects. Patients with renal failure, who are Antihistamines on antacids, may develop toxicities and adverse reactions. Antihistamines are antagonists to histamine, their mecha- Other patients may, for example, develop a metabolic alka- nism of action being a competitive inhibition of naturally losis from prolonged or generous administration of sodium occurring histamines at the H1 receptors. Once H1 receptors bicarbonate. Aluminum-containing antacids should be are occupied by antihistamines, such as diphenhydramine, avoided in patients with Alzheimer’s disease. Antacids will the development of further histamine-induced angio- generally reduce the absorption of digoxin, possibly leading to dysrhythmia.63 edema, pruritis (itching), and bronchospasm is impeded. Antihistamines do not reverse pre-existing pathology Of greater concern is the altered absorption of many med- (e.g., vasodilation-induced hypotension). Furthermore, the ications as a result of changed stomach acidity. For example, pharmacokinetics in antihistamines are gradual, with an the pharmacokinetics of drugs that are weak bases, such as onset of action between 15 and 30 minutes (with a peak in antihistamines and tricyclic antidepressants, and drugs that one hour). are weak acids, such as sulfonamides and salicylates, will During anaphylaxis, time is of the essence and the drug be altered. Since the list of drug interactions with antacids of choice remains epinephrine.62 Epinephrine, administered is long, Paramedics should consider drug interaction when subcutaneously, has an immediate effect and reverses the assessing a patient who is also taking antacids. symptoms present in anaphylaxis. Epinephrine’s mechanism of action was previously discussed. Histamine Antagonists Histamine antagonists (discussed earlier), particularly the Drugs That Are Used to Treat H2 receptor blockers, are effective in inhibiting all phases of stomach acid secretion. Many examples of histamine Gastrointestinal Disorders From ancient Greece, when Hippocrates spoke of the runny “faeces” of dysentery, to contemporary discussions Street Smart of infantile diarrhea in developing countries, gastrointes- tinal complaints have historically plagued humanity. Many concoctions have been created to combat this malady. Patients will dismiss epigastric discomfort as being Oil of earthworm, listed in the Leiden pharmacopoeia in heartburn, denying the possibility that they are having 1741, was replaced by paregoric (liquid opium) in 1788. a heart attack, and will self-medicate with antacids Opium’s popularity is owed, in part, to its ability to con- (without relief). Paramedics should always have a high stipate, to “bind the bowel,” and halt diarrhea. Subsequent mineral preparations had some degree of success and an index of suspicion that heartburn has a cardiac origin entire pharmaceutical industry was created to treat this (an inferior wall AMI) and treat accordingly. common disorder.28 Pharmacological Therapeutics for Medical Emergencies 703 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. antagonists, such as cimetidine and ranitidine, are now avail- For example, drugs in the class of phenothiazines (such as able over-the-counter. chlorpromazine) and promethazine or metoclopramide stop nausea before the process of vomiting can be started. Emetics Anticholinergics can block acetylcholine receptors The quintessential emetic agent is syrup of ipecac. Used for located within the emetic center, thereby preventing vomiting. centuries as a purgative, it stimulates vomiting by both irri- This is the mechanism of action for scopolamine. Similarly, tating the stomach and rousing the vomiting centers in the histamine receptors in the emetic center can be blocked by brain. Syrup of ipecac is highly effective (greater than 80% antihistamines such as diphenhydramine or dimenhydrinate. of patients will vomit) and has a quick onset of action (within Another anti-emetic is odansetron, (Zofran®). Odansetron, 20 minutes).64 selective serotonin receptor antagonist, is especially effective as a pretreatment for nausea and vomiting, Some providers have Toxicity reported transient ECG changes, particularly QT prolongation, Syrup of ipecac itself can be both neurotoxic and cardiotoxic with intravenous odansetron administration. As ondansetron and caution is advised anytime it is used. Emetine, the active treats the symptom, not the cause of nausea, assessment and ingredient in syrup of ipecac, is part of a mixture of alkaloids treatment of the underlying cause is imperative. obtained from the plant Rubiaceae (Cephalus ipecacuanha). Cannabinoids (synthetically produced THC, such as the Emetine is derived from tyrosine, the intermediary of do pamine, type found in marijuana) have two therapeutic advantages. which explains its effects upon the heart and brain. First, cannabinoids are antiemetic. Second, cannabinoids The delay between the onset of symptoms from a poison stimulate appetite and reduce anorexia. This advantage can and the onset of action of the syrup of ipecac is a concern for be critical when treating patients who are cachetic secondary most Paramedics. If there is any possibility that the toxin can to acquired immunodefi ciency syndrome or chemotherapy.66 induce drowsiness or unconsciousness before the ipecac can take effect, then the ipecac should be withheld. For this rea- Antidiarrheal son, the routine use of syrup of ipecac is not recommended by To be medically accurate, diarrhea is not loose watery stool, the American Academy of Clinical Toxicology.65 but rather a frequent passage of loose watery stool. Certain populations, such as the very old and very young, are at risk for dehydration from diarrhea. Chronic diarrhea (diarrhea that lasts for more than one week) can be indicative of intes- Street Smart tinal infections such as amebic dysentery. Acute diarrhea can be indicative of toxin ingestion and bacterial infection, such The American Academy of Pediatrics no longer as salmonella or escherichia coli. advocates the civilian use of syrup of ipecac and In many cases, resolution of the underlying cause will alleviate the symptom. In cases where more immediate relief encourages that all syrup of ipecac be discarded. is sought or where the patient expects a short course of ill- Syrup of ipecac should only be used, in the hospital ness, then antidiarrhea agents are available. setting, under the direct orders of a physician. Absorbents Absorbents essentially coat the bowel wall, preventing inter- action of the intestine and bacteria or toxin, thereby stopping Antiemetics intestinal irritation and subsequent diarrhea. An example of Unremitting vomiting (e.g., from chemotherapy) can be debil- an absorbent antidiarrheal agent is bismuth subsalicylate. itating and lead to potentially life-threatening dehydration This bismuth preparation also contains salicylate, the active and hypovolemia. The majority of antiemetics work centrally, ingredient in aspirin, and can increase bleeding times. in the brain, to control the nausea that leads to vomiting. This Another example of an absorbent agent commonly used area, called the chemoreceptor trigger zone (CZT), contains by Paramedics is activated charcoal. Activated charcoal, a sensory nerves that detect poisons and

the like in the blood. fi nely pulverized form of charcoal, absorbs the toxins until The CTZ then triggers the emetic center in the brainstem passage out of the intestine. To aid excretion, an indigestible to induce vomiting. This primitive protective mechanism is osmotic agent such as sorbitol is added. most effective with ingested toxins. Opioids Mechanism of Action Paregoric and tinctures of opium have been used as antidi- The mechanism of action of an antiemetic generally involves arrhea agents for centuries. However, recent concern about blocking a receptor (an antagonist) along the neuromuscu- the addictive quality of these medicines has brought about lar chain that leads to vomiting. Dopamine receptors, located a decrease in their use. Nevertheless, these opioids remain within the CTZ, can be blocked by dopamine antagonists. highly effective in the control of diarrhea. 704 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Loperamide, a synthetic opioid, decreases the peristalsis Precautions associated with diarrhea and permits reabsorption of water. Laxatives should not be routinely used to treat abdominal This prescription medication has a duration of action of over pain thought to be due to constipation. Undiagnosed abdomi- 24 hours, making it effective when traveling in remote or nal pain can be the presenting symptom for appendicitis, frontier areas. enteritis, and mesenteric infarction. Laxatives Older patients are frequently plagued by constipation as their Drugs That Are Used to Treat gastrointestinal tracts slow. In some cases, constipation can Bleeding Disorders lead to life-threatening small bowel obstruction. There are numerous causes of obstruction, but the effect is the same: The origins of bleeding disorders can be genetic (e.g., hemo- blockage of the intestinal tract. philia), disease-induced (e.g., disseminated intravascular coag- There are as many treatments for constipation as there ulation), or iatrogenic (e.g., heparin infusion). Regardless of are causes of constipation. Treatments for constipation can be the etiology the result is the same: a coagulopathy (defect in organized into broad classifi cations based upon the mecha- blood clotting). Consequently, the patient either clots too much nism of action. or bleeds too much. Drugs that affect blood clots (antithrombolytics and Saline Laxatives antifi brinolytics) were discussed in Chapter 30. Treatment of bleeding disorders revolves around either use of antagonists As soluble salts, these laxatives dry the water in the intestinal that interfere with anticoagulant medication or replacement tract via osmosis. The result is an increased fecal mass and of missing coagulation factors. stimulation for evacuation. Many of these saline laxatives Anticoagulants (such as warfarin) antagonize the fat- contain other minerals that may have added side effects. An soluble vitamin K, an essential cofactor in the coagulation example of a commonly used saline laxative is magnesium cascade. In some instances, the administration of vitamin K hydroxide, otherwise known as milk of magnesia. It can have overcomes the warfarin dose and re-establishes normal clot- a toxic effect on the kidneys. Others high in sodium compli- ting. Unfortunately, vitamin K is slow acting and can take cate the management of a patient’s heart failure or hyperten- up to 24 hours to be effective.67 This single quality makes sive control. vitamin K less useful in an emergency. Other anticoagulant antagonists work in direct opposi- Stool Softeners tion to the action of the fi brinolytics. Fibrinolytics act by Stool softeners act as a wetting agent, softening the fecal mass encouraging plasminogen activators to degrade fi brin. These until it can be passed. An example of a commonly prescribed anticoagulant antagonists (such as aminocaproic acid) inhibit stool softener is docusate. Docusate is often given to post-MI plasminogen activators. patients to prevent straining during bowel movements and the Heparin, a commonly prescribed anticoagulant, is subsequent vasovagal stimulation that occurs. formed in the liver, lungs, and intestinal lining. It produces its anticoagulant effect by binding with naturally occurring Bulking Agents antithrombin III and inactivating several factors in the coagu- lation cascade. Bulking agents, such as psyllium, absorb water from the The heparin antidote, protamine sulfate, is a protein fecal fl ow, increasing the volume of the feces and distend- obtained from the sperm of salmon that has an ability to inter- ing the bowel. The distended bowel is now encouraged to fere with the heparin-antithrombin III complex and thereby empty refl exively. prevents anticoagulation. Stimulants Antihemophilic Drugs Stimulants act directly upon the nervous control of the bowel, Uncontrollable bleeding secondary to a minor injury can be increasing peristalsis and bowel emptying. Stimulants, such life-threatening to a patient with hemophilia. Born with an as senna, can also produce abdominal cramping and pain. inability to produce one of the protein-clotting factors in the Senna tea, an old world remedy, is made from an infusion of blood, these patients may have excessive bleeding into the leaves of the Cassia plant into a tea. joints, bladder, and brain.68 The most common hemophilia (hemophilia A) is a defi - Lubricants ciency of factor VIII or the antihemophiliac factor (AHF). Lubricants aid the naturally occurring mucus to coat the feces Administration of cryoprecipitated AHF, prepared by rapid for an easier bowel movement. Many of these oil-based lubri- freezing and thawing of fresh plasma, is useful during an cants can also block absorption of fat-soluble vitamins, such emergency. As a glycoprotein, AHF is needed to transform as vitamins A, D, E, and K. prothrombin into thrombin. Pharmacological Therapeutics for Medical Emergencies 705 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Following AHF administration, it is common to admin- poorly absorbable ferrous carbonate. Other nutrient supple- ister anti-inhibitor coagulant complex. Anti-inhibitor coagu- ments used to treat various types of anemia include folic acid lant complex is also obtained from plasma and is often used and cyanocobalamin (vitamin B12). Vitamin defi ciencies can preoperatively for those with factor VIII defi ciency. occur as a result of poor diet and are often seen in patients Similarly, factor IX complex is administered to patients with alcoholism. with hemophilia B (Christmas disease) to prevent or con- trol bleeding. Drugs That Are Used to Treat Psychiatric Disorders In the past, the diagnosis of a psychiatric illness would bring Street Smart out images of raving mad lunatics locked in an insane asylum forced to undergo bizarre medical treatments, such as frontal Absorbable gelatin sponges, fi lm, powder, and lobotomy and straitjackets. Historically, mentally ill patients oxidized cellulose gauze are moving out of the were warehoused in public mental hospitals with deplorable health and sanitation conditions. Documentaries, such as the operating room and into the street. These topical one on Millbrook, brought these appalling conditions to light hemostatic agents are capable of absorbing blood in and efforts were made to change conditions and the therapeu- large quantities and encouraging clot formation at the tic approach. Psychiatrists, encouraged by the effectiveness bleeding site. of antibiotics, turned their attention to medications. They were not disappointed. The impact of the fi rst tranquilizer (chlorpromazine) in the 1950s cannot be overstated.71 Patients, who were previ- Anemia ously labeled dangerous and uncontrollable, could be tran- Anemia is not a disease. More accurately, anemia is a symp- quilized, treated, and, in some cases, allowed to lead a normal tom of other diseases that involves the body’s inability to public life. form adequate red blood cells. In most instances, anemia is The development and widespread use of these psychi- the result of either a dietary defi ciency of needed nutrients or atric medications led to the widespread deinstitutionaliza- poor absorption of those needed nutrients. tion of hundreds of psychiatric patients, It also prompted a In some instances, the anemia is a quasi-anemia (i.e., complete change in the focus of mental health medicine away one induced by a temporary state such as pregnancy). In from institutionalization and toward community-based treat- other instances, chronic blood loss, infection, cancer, or ment centers. drug-induced bone marrow depression can produce anemia. Psychosis Regardless of the cause, the patient has a less than normal hemoglobin (Hb) concentration from either fewer circulat- A large number of mental illnesses can be grossly catego- ing red blood cells or a low hemoglobin content in those red rized under the label of schizophrenia, anxiety disorders, and blood cells. depression. Medications to treat patients who suffer from Treatment of anemia is usually geared toward providing each of these mental illnesses are described further. supplementary nutrition while eliminating or treating the root The patient with a diagnosis of schizophrenia has dem- cause of the anemia. A common anemia, iron-defi ciency ane- onstrated disturbances in thought. Hallucinations, particu- mia, can occur from chronic blood loss, including menses. larly audible hallucinations and delusions, plague the patient. Iron, which is essential for the red blood cell to carry oxygen, The outcome of this deranged thinking, and what usually is prescribed to those patients suffering from a defi ciency. brings the patient to the Paramedics’ attention, is an inability Iron stored in the intestinal mucosa can also be lost in gastro- to perform the routine activities of daily living (ADL) such as intestinal disease. bathing and clothing oneself. If children accidentally ingest iron supplements, it can turn into a medical emergency.69 As the iron is absorbed, Drugs That Are Used to Treat Psychosis the child can become toxic and will have diffuse abdominal Antipsychotic medications help provide the patient with signs, such as cramps.70 Unfortunately, the symptoms sub- symptomatic relief from the frightening hallucinations and side within 24 hours and the patient appears fi ne, which may deranged thoughts caused by schizophrenia. While these prompt them not to seek further treatment. Subsequently, medications induce a tranquil state in the patient, allowing about 48 to 72 hours later, an acidosis occurs that can lead to the patient to cope with the illness, they are not a cure for pulmonary edema, convulsions, and hyperthermia. schizophrenia. Therefore, in order to maintain control of the If ferritin intoxication is suspected, the Paramedic may disease patients must remain on the drug for long periods of induce vomiting using syrup of ipecac and/or lavage with time. Setbacks for these patients are frequently the result of sodium bicarbonate solution, which converts the ferritin into poor compliance with prescribed medications and subsequent 706 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. breakthrough psychosis that is often manifested in aggressive Fortunately, most of these symptoms are self-limited and or combative behaviors. diminish with the termination of the medication. The phenothiazines, the major class of antipsychotic medications, are thought to block dopamine receptors within Anxiety the limbic portion of the brain. (The limbic system is the seat of emotions.) This blockade results in a reduction in halluci- As a class, sedatives affect the limbic system and thus emo- nations and subsequent agitation. However, it should be noted tions. Sedatives effectively reduce anxiety (i.e., anxiolytic) that the phenothiazines do not depress the patient’s intellec- as well as induce sleep (i.e., hypnotic). Some of the most tual function or native intelligence. commonly known sedatives are the barbiturates and the ben- Phenothiazines can be further broken down, according zodiazepines. When used early, the barbiturates can create to chemical makeup, into three subcategories. The fi rst phe- an anxiolysis, even in small doses (doses too low to induce nothiazines were all aliphatic phenothiazine derivatives (e.g., respiratory depression). The

use of barbiturates for anxiolysis chlorpromazine). The next subcategory of phenothiazines has declined in favor of benzodiazepines. This is, in part, due includes the piperidine derivatives, such as thioridazine. The to the greater safety margin of benzodiazepines over barbitu- last subcategory of phenothiazines are the piperazine deriva- rates. The lethal dose of barbiturates is only some 50 times tives (e.g., prochlorperazine). greater than the therapeutic dose, whereas the lethal dose of Most phenothiazines have a strong antiemetic effect, benzodiazepines is one-thousand times greater than the ther- which blocks the chemoreceptor trigger zone (CTZ) within apeutic dose. the medulla. The most famous of these is scopolamine, which is used to treat motion sickness. Many patients who are receiv- Benzodiazepines ing chemotherapy for cancer are prescribed a phenothiazine, Benzodiazepines are effective for treating such anxiety- such as chlorpromazine, for nausea control. related disorders as panic attacks, as well as seizure activity, by attaching to benzodiazepine receptors located in the Limbic Precautions system of the central nervous system. These benzodiazepine Phenothiazines also exert an antagonistic infl uence on receptors are thought to enhance the attraction of gamma- other receptors. The majority of side effects attributed to aminobutyric acid (GABA) to the GABA receptor, which in the phenothiazines can be traced to this broad blockade of turn opens chloride channels in the neuron. Increased chlo- other receptors. For example, phenothiazines block alpha- ride (Cl-) within the cell hyperpolarizes the neuron, making adrenergic receptors in the peripheral circulation. As a direct it more diffi cult to depolarize. consequence of this blockade, when a patient stands up the Benzodiazepines are also used for a number of other cardiovascular system cannot compensate and the patient therapeutic effects including treatment of sleep disorders may experience syncope.72 (hypnotic effect), seizures (see earlier discussion), and More troubling may be the antimuscarinic effects of phe- muscle spasms. However, the majority of benzodiazepines nothiazines. Through its inhibition of smooth muscle, phe- are prescribed for their anxiolytic effect. Short-acting ben- nothiazines cause the patient to experience blurred vision zodiazepines, such as lorazepam, are effective in ending (papillary muscle), dry mouth, constipation, and urinary panic attacks. Long-acting benzodiazepines are effective in retention. treating the agitation and anxiety patients experience when they go through alcohol withdrawal. It should be noted that Extrapyramidal System ethanol (ethyl alcohol) is also a sedative. The therapeutic goal in alcohol detoxifi cation is to fi rst replace the alcohol Coordination of muscles is owed, in part, to the extrapyra- with a benzodiazepine, then to slowly wean the patient off midal system that connects the motor coordination from the of the benzodiazepine. cerebral cortex with the spinal nerves. There are abundant cholinergic and dopaminergic receptors within this system. A naturally occurring imbalance between these two receptors Antidepressant Medication is the pathogenesis of Parkinson’s disease. Phenothiazines Depression is a disturbance in a patient’s mood, not thought, can produce a drug-induced Parkinsonian syndrome. and is characterized by feelings of hopelessness, helpless- Characteristics of the extrapyramidal symptoms (EPS) of ness, and despair. Some psychiatrists attribute these mal- drug-induced Parkinsonian syndrome include a shuffl ing gait, adjusted emotions to a lack of a certain neurotransmitter resting tremors, muscle rigidity with resultant slurred speech, in the brain, specifi cally the monoamines. Monoamines drooling, and a gross motor restlessness called akathisia.73 include norepinephrine and serotonin. Antidepressant med- If left untreated, drug-induced Parkinsonian syndrome ications that have had a positive effect are medications that can lead to involuntary movements of the extremities (a either increase the amount of monoamines in the synaptic tardive dyskinesia). These include fl y-catching motions of junction or decrease the destruction of monoamines by the tongue and a spasm of the neck muscles, called torticol- enzymes, indirectly increasing the amount of monoamines lis, that tilts the head to one side (formerly called wryneck). in the synaptic junction. Pharmacological Therapeutics for Medical Emergencies 707 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Tricyclic Antidepressants Selective Serotonin Re-Uptake Inhibitors The class of antidepressants that block the uptake of sero- Selective serotonin re-uptake inhibitors (SSRI) preferentially tonin, norepinephrine, and dopamine into the neuron are block the re-uptake of serotonin into the neuron and thus, called the tricyclic antidepressants. The fi rst generation of indirectly, increase the amount of neurotransmitter in the syn- tricyclic antidepressants (TCA), including imipramine and aptic cleft. The SSRI drugs are thought to have less impact on amitriptyline, are chemically related to the phenothiazines the parasympathetic nervous system as well as fewer cardio- and have similar mood-altering effects. The second genera- vascular side effects such as orthostatic hypotension. tion of TCA also has the same action but slightly different pharmacokinetics, with different side effects and a longer Monoamine Oxidase Inhibitors duration of action. Monoamine oxidase is an enzyme that metabolizes excess The primary action of TCA is to increase the mono- catecholamines, through a process of oxidation, into inactive amines serotonin, norepinephrine, and epinephrine in the metabolites that can be harmlessly excreted. MAO inhibitors brain’s neuronal synapse. At issue is whether the antidepres- prevent the deactivation of catecholamines from the synap- sant effect is due to increased monoamines or the observed tic gap and therefore indirectly increase the amount of neu- subsequent increase in monoamine receptors in the brain. rotransmitter in the synaptic junction. The MAO inhibitors Regardless, TCA administration results in mood elevation, are similar to TCA in effect, but different in their pharmaco- improved mental alertness, and increased physical activity. dynamics, as they elevate the patient’s mood. The TCA, as a class, are effective in between 50% and 70% Tyramine, the fundamental substance for monoamines of patients taking the medication. such as norepinephrine, is found in such foodstuffs as aged cheeses, fermented sausages (such as bologna, pepperoni, Precautions salami, and summer sausage), sauerkraut, smoked or pickled Tricyclic antidepressants also affect a number of other meats, beer, and red wines. peripheral neural receptors including serotonin, alpha- Typically, tyramine is metabolized in the intestines by adrenergic receptors, and muscarinic receptors. TCA can MAO. When the patient has been placed on an MAO inhibi- block muscarinic receptors in the parasympathetic nervous tor, tyramine-rich foods are absorbed unaltered into the cir- system, resulting in dry mouth (xerostomia), blurred vision, culation. Tyramine taken up by the neurons displaces the and urinary retention.74 monoamines in the neuron’s vesicles, liberating large quanti- Tricyclic antidepressants also increase catecholamine ties of catecholamines. activity in the heart while blocking alpha-adrenergic recep- The resulting increase of catecholamines in the neuronal tors in the peripheral capillary beds. Subsequently, when a synapse leads to profound sympathetic stimulation. Subse- patient stands suddenly the central nervous system cannot quently, tachycardia and hypertension ensues and can lead to refl exively adjust to the sudden change in blood distribution a potentially life-threatening hypertensive crisis. and the patient experiences orthostatic syncope. Mania Toxicity Psychotic depression is discernible by extremes of mood. The depressed patient may elect to attempt suicide by inges- One moment the patient is depressed, voicing hopelessness, tion of the TCA prescription. A TCA overdose can be danger- and the next moment the patient is elated and demonstrates ous at many levels. Alone, TCA blocks sodium channels in self-confi dence beyond reason. Patients exhibiting these the heart, leading to complex cardiac conduction abnormali- behaviors are said to be bipolar (i.e., manic–depressives) and ties including AV block, reentry ventricular dysrhythmia, and must be treated for both extremes in emotion. ventricular tachycardia, including polymorphic ventricular Lithium Salts tachycardia (specifi cally torsades de pointes).75,76 Co-ingestion of depressants, such as alcohol, along The prototypical anti-mania drug is lithium. While lithium with the TCA can lead to a toxic sedation. Similarly, if the salts are very effective, the therapeutic index for lithium patient ingested MAO inhibitors (another antidepressant) is very low. Effects of lithium intoxication include ataxia along with the TCA, the two drugs can produce a signifi cant (drunken staggers), confusion, and convulsions.78 sympathetic overstimulation that manifests as high fever (hyperpyrexia) that mimics heat stroke, marked hyperten- Drugs That Are Used to Treat sion, and convulsions. Treatment of a TCA overdose is aimed at reversing these Childbirth Emergencies negative cardiovascular effects and protecting the airway. Traditionally, medications are used sparingly during pregnancy After controlling the airway, alkalinization of the blood with for fear of possible teratogenic effects. However, under certain sodium bicarbonate (0.5 mg/kg) may be the initial treat- special circumstances it may be necessary to use medication. ment.77 The sodium bicarbonate bolus is usually followed by In those instances, the Paramedic should review the drug’s an intravenous infusion of sodium bicarbonate. pregnancy classifi cation as well as contact medical control. 708 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Eclampsia even on one organ system. Terbutaline, a smooth muscle relax- ant (beta-adrenergic agonist), has been given intravenously Eclampsia, also known as toxemia of pregnancy, is the cul- (0.025 mg/min IV drip) with some success. However, signifi - mination of a syndrome called pre-eclampsia. It is dramati- cant side effects limit its use to emergencies only. cally revealed by the pregnant woman’s convulsion between her third trimester (twentieth week) and immediately post- Oxytocics partum. Pre-eclampsia produces hypertension (rise in the baseline systolic pressure by 31 mmHg), protein in the urine Labor, the forceful contraction of the uterine smooth mus- (albuminuria), and peripheral edema. cles, is induced by the hormone oxytocin which is secreted Treatment of eclampsia has two objectives: stop the con- from the posterior pituitary gland. Oxytocin, which trans- vulsion and preserve the life of the fetus. If left untreated, lated literally means “rapid birth,” is made synthetically and the mother’s eclampsia-induced convulsion can lead to coma can be intravenously administered by Paramedics during a and stress the unborn infant. A higher incidence of placenta pregnancy- related emergency. abruptio has also been noted following eclampsia-induced The onset of action of synthetic oxytocin, such as convulsions. ergonovine or oxytocin itself, is almost immediate (one to six While diazepam is effective in treating the convulsion, minutes) and causes uterine contractions to gradually increase evidence suggests that magnesium sulfate remains superior over one hour. The strong contractions of the uterus tend to for the treatment of eclampsia.79 Whenever magnesium sul- compress blood vessels and slow intrauterine bleeding. fate is administered, careful monitoring of blood pressure, pulse, respirations, and fetal heart sounds (when possible) should occur at least every 15 minutes. Street Smart It is important that Paramedics make the distinction between the mother who is experiencing an eclampsia-induced convulsion and one with a pre-existing seizure disorder. This Stimulation of the mother’s nipple stimulates milk distinction is important when selecting preferred agents for discharge from the breast via release of oxytocin. emergency treatment. If uncontrolled, a convulsion can lead This cause and effect is called the letdown refl ex. to fetal anoxia and brain damage. Therefore, it must be treated immediately with the most effective anticonvulsant agent. Therapeutically, stimulation of the mother’s nipple, by the suckling infant, can also release oxytocin Labor that will cause uterine contractions and help control Complications of pregnancy, such as premature labor, pre- hemorrhage. term delivery, and breech deliveries, make the fi eld deliv- ery of an infant more dangerous. In certain situations, it is desirable to inhibit the labor of a pregnant woman in favor of effecting an immediate transfer of the mother to a better Drugs That Are Used equipped birthing center. Another serious complication of pregnancy is post- to Combat Infection partum hemorrhage. When the products of conception are An infection occurs whenever any microorganism, such as a incompletely removed from the uterus following labor, virus, bacteria, parasite, fungus, or worm (helminth), invades such as incomplete placental detachment, then

the mother the body and overcomes the host’s native defenses. Without may hemorrhage uncontrollably. In those cases, Paramedics medical intervention, these infections can lead to generalized may institute a life-saving infusion of medication to force sepsis, septic shock, and even death. uterine contraction. The best defense against infection is prevention. Para- medics can utilize a variety of techniques to try and prevent Tocolysis infection. The fi rst assumption of infection control is that Medications that cause uterine relaxation, and thus pathogens (microorganisms capable of producing infec- inhibit labor, are called tocolytics. Some tocolytics, such tion) are omnipresent in the community and within the work as ethyl alcohol (inhibits oxytocin) and aspirin (inhibits environment. To limit their transmission (i.e., prevention), p rostaglandin-induced labor), are impractical in the fi eld. Paramedics use a variety of barrier devices (gloves, goggles, In some cases, a simple bolus of intravenous solution can mask, and gown) as well as aseptic techniques. be temporarily effective. The bolus of intravenous solution Hypothetically, a complete lack of all microorganisms activates antidiuretic hormone from the posterior pituitary (surgical asepsis) would be the most desirable situation for gland and also inhibits oxytocin secretion from the poste- EMS. However, surgical asepsis is only possible via steril- rior pituitary as well. ization and is therefore impractical in the fi eld. More real- Hypothetically, any smooth muscle relaxant should also istically, the Paramedics’ goal should be to attain medical inhibit labor, as few drugs work exclusively in one organ or asepsis (an absence of pathogenic microorganisms) in the Pharmacological Therapeutics for Medical Emergencies 709 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. fi eld. Medical asepsis is obtained through a combination of Some antibiotics are effective against a large number of hygienic measures, such as hand washing, barrier devices, bacteria (i.e., the antibiotic is nonspecifi c) and thus are classi- antiseptics, and disinfectants. fi ed as broad-spectrum antibiotics. Other antibiotics are very Disinfectants are solutions and compounds, such as the effective for only a specifi c bacteria. For example, isoniazid phenols and chlorine compounds, which effectively remove is only effective against mycobacterium tuberculosis, and pathogens from inanimate objects, such as work surfaces and thus is classifi ed as a narrow-spectrum antibiotic. assessment tools. However, they are generally toxic when In many cases, a patient will be placed on a broad-spectrum they come in contact with living tissue. Therefore, disinfec- antibiotic while awaiting laboratory results of cultures obtained tants cannot be used in the treatment of patients unless their from the patient. With the results in hand, more specifi c, or potency is reduced (e.g., through dilution). Weakened, these narrow-spectrum, antibiotic therapy would be prescribed. solutions tend to inhibit, rather than destroy, pathogens and Antibiotics can bring about their antimicrobial effect by are thus called antiseptics. several means, including inhibiting cell wall synthesis, inhib- Antiseptics, as well as disinfectants, can be further iting protein synthesis, or as an antimetabolite. categorized as either bacteriostatic (solutions that slow the growth of pathogens) or bactericidal (solutions that kill off Antibiotics That Inhibit Cell Wall Synthesis the pathogens). Some solutions are effective against a broad Bacteria, unlike native cells, are not isotonic in the intersti- spectrum of pathogens (i.e., fungi, virus, and bacteria) and tial fl uid. The resulting osmotic pressure places a great strain are called germicides. An effective disinfectant must be able upon the bacteria’s cell walls. Any antibiotic that weakens to kill off all bacteria (not spores), fungi, parasites, and most that cell wall (e.g., by inhibiting the synthesis of portions viruses within 10 minutes of application. of the cell wall) will cause the cell wall to structurally fail and the cell to burst (i.e., lysis). Antimicrobials The pharmacodynamics of the fi rst antibiotic (penicillin) works by this mechanism. Subsequent generations of antibiotics, Despite meticulous medical asepsis, infections do still occur. such as the cephalosporins, also depend on this mechanism.80 Medical intervention is necessary to prevent the spread of Allergies to penicillin are common, occurring in about infection. Treatments for infection can be broken down into 5% of the U.S. population.81 Not surprisingly, patients who surgical treatments and medical treatments. Surgical treat- develop an allergy to penicillin drugs often have a cross- ments include the debridement of dead and necrotic tissue, allergy to the cephalosporins as well, since the two are incision and drainage of infection, and excision of infected chemically related. Newer broad-spectrum penicillins, such organs. A discussion of surgical treatment is beyond the as piperacillin, are among some of the most widely used anti- scope of this text. biotics because of their wide safety margin. Unfortunately, Medical treatments for infection include the use of chem- overuse and poor patient compliance has led to the devel- icals (i.e., drugs) for their therapeutic benefi t. Organization opment of penicillin-resistant bacteria, the c reation of super- of these chemotherapeutic agents can be arranged according infections, and subsequently limited the usefulness of these to the pathogen that the drug is most effective against. For inexpensive antibiotics. example, antibiotics are drugs that are effective against bac- teria and antivirals are most effective against viruses. Antibiotics That Inhibit Protein Synthesis Antivirals Inhibition of protein synthesis within the bacteria’s cytoplasmic ribosome by these antibiotics causes the bacteria to misread Viruses, the smallest pathogen, are incapable of independent the genetic code. Unable to properly synthesize the necessary reproduction and, as parasites, require a host cell for replica- proteins for cell reproduction, the bacterium dies. Tetracy- tion. Understanding how important this simple process is to a clines, aminoglycosides, erythromycin, chloramphenicol, and virus’s infectivity, antiviral treatment is focused on preventing clindamycin are all antibiotics that work by this mechanism. the virus from injecting (i.e., uncoating) its RNA into the host cell or inhibiting the synthesis of DNA once the virus is inside. Antibiotics That Are Antimetabolites Unfortunately, due to the close relationship of the virus to the Bacteria, like the host, require certain substrates for the pro- host cell, it is diffi cult to kill one without eliminating the other. duction of proteins and the like. For example, one of those substrates is folate. Folate, which is produced by the bacteria Antibiotics from PABA, is converted into folic acid, an essential cofactor The sheer number of antibiotics available on the market is in amino acid synthesis. The sulfonamide class of antibiotics staggering. To lend order to this collection, antibiotics can competes with bacteria for the enzymes necessary for this be further classifi ed according to their action. Minimally, conversion, thus inhibiting the bacteria’s ability to produce antibiotics should suppress bacterial infections, allowing the amino acids and proteins. Isoniazid (IND), a potent antituber- host’s defenses to overcome the infection (e.g., tetracycline culosis agent, works by a similar mechanism, inhibiting the or erythromycin) or even destroy the invading pathogen (e.g., synthesis of mycolic acids. This, in turn, weakens the myco- aminoglycosides, cephalosporins, and penicillins). bacterium’s cell wall. 710 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Antifungals Chemotherapy is one of the three mainstays of cancer treatment, the other two being radiation and surgery. Chemo- Of the over one million varieties of fungus, over 400 are known therapy is aimed at eliminating the cancer at the cellular level. to cause disease in humans. So many varieties of fungus exist In some instances, the chemotherapy is calculated to reduce that fungus is categorized as one of the fi ve kingdoms of life. a tumor’s mass for surgical removal later. In other cases, the Fungus is identifi able by its rigid cell walls, among other char- chemotherapy is intended to eliminate any remaining cancer acteristics, which makes it particularly resistant to most antibi- cells (micrometastases) after surgery and/or radiation. otics. Fungal infections, called mycoses, are generally treated Drugs that eradicate cancer cells are called antineoplastics. with antibiotics that disrupt the cell wall of the fungus, making These antineoplastic drugs depend upon the rapid division of it more permeable. The cell walls are now “leaky,” essential the dysfunctional cells within a tumor to be effective. To prolif- substrates (such as potassium) leak out, and the cell dies. erate, cancer cells depend on amino acids and nucleic acids in Antiprotozoal order to build DNA and RNA. By understanding this concept, chemotherapies are designed that deprive the cancer cell of Protozoa, a one-celled organism, may be the most abundant these essential substrates (i.e., antimetabolites), block the tran- life form on Earth, creating more “biomass” than any other life scription of RNA to new DNA (called mitotic inhibitors), or form. Of particular concern to Paramedics are the protozoa that prevent cell division entirely (such as the alkylating agents). cause malaria and the protozoa that cause amebic dysentery. All antineoplastic agents are also effective against cell Malaria, carried in mosquito saliva, is a blood-borne division among normal healthy cells, particularly the rapidly infection. dividing epithelial cells of the mucus lining in the intestine, Roughly 40% of the world’s population is at risk for the dermis of the skin, and the hair. Thus, the margin between malaria. In fact, it is estimated that one African child dies the therapeutic and toxic margins of antineoplastic agents is every 30 seconds from malaria.82 extremely narrow and serious side effects frequently occur. Acute dysentery, characterized by large amounts of A common side effect is a decline in the number of white mucus-laden diarrhea and severe abdominal pain, is the con- blood cells. At the peak (nadir) of the chemotherapy’s effec- sequence of intestinal amebic infection. If left untreated, dys- tiveness, the patient’s white blood cell count will be at its lowest entery can lead to profound hypovolemia and shock. (leukopenia) and the patient will be seriously immunocompro- While improved sanitary conditions have decreased the mised. With a limited immunity, opportunistic infections can incidence of these two diseases in the United States, immi- obtain a foothold and the patient can become septic. Often the grants from other countries and tourists traveling abroad can fi rst sign of infection is a fever of unknown origin.83 bring the disease back in the Americas. Similarly, at the nadir of the chemotherapy the patient’s Pregnancy and Protozoa platelet count will also drop. The resulting thrombocytopenia will leave the patient at greater risk for spontaneous hemor- A particular concern of pregnant women is the possibility of con- rhage (e.g., cerebral hemorrhage) and bruising. tracting toxoplasmosis. The causative agent in toxoplasmosis is toxoplasma gondii, a protozoa that is carried in the feces of cats as an oocyst (encapsulated protozoa). Absorbed systemically, the protozoa are transferred to the fetus and can cause blindness, Street Smart loss of hearing, and mental retardation. For this reason, women who are pregnant are advised to not empty cat litter boxes. The nadir of chemotherapy usually occurs in the Antihelmintics middle of the cycle (e.g., on the seventh day of a 14-day cycle). At this time, the patient is at greatest The helminthes (worms) include blood fl ukes, fl atworms, and tapeworms. (Ringworm is a fungal infection.) These worms risk for acquiring infection. Paramedics should can be present in undercooked beef or pork, or transmitted by practice reverse isolation when caring for this patient. common vectors, such as the mosquito, horse fl y, or black fl y. Treatment of worms is aimed at the specifi c helminth that has been identifi ed. Interestingly, a number of the treatments Palliative Care paralyze the worm. When co-administered with laxative, the body then can purge the infestation. In many instances, all a Paramedic can do is offer support and palliative measures to patients with cancer. Palliative measures Drugs Used to Treat Cancer are those treatments

that are intended to alleviate the unpleas- ant symptoms of chemotherapy with antineoplastic agents. Cancer is the second leading cause of death in the United Common symptoms associated with chemotherapy include States. One in four patients will have a diagnosis of cancer in nausea, vomiting, anorexia, and diarrhea. Use of antiemetics— his or her lifetime. The goal of cancer treatment is to elimi- such as promethazines, phenothiazines, and antihistamines— nate the cancer from the body. may bring the patient much needed relief and comfort. Pharmacological Therapeutics for Medical Emergencies 711 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Paramedics have a limited arsenal of effective chemotherapeutic agents with which to fi ght disease. Despite this apparent disability, thoughtful Paramedics can intervene early in an emergency with this limited number of medications and reduce the morbidity and mortality associated with these diseases. Key Points: • The brain consists of the brainstem (the primitive refl ex arcs in the spinal cord, causing an immediate brain), the cerebellum, and the cerebrum. withdrawal from the stimulus. • Only lipid-soluble drugs are capable of passing into • Neuromodulators are substances that affect the brain tissue. This blood-brain barrier is the result transmission of pain sensations to the brain. of tight slit junctions, gaps in capillaries that allow Endorphins are natural neuromodulators and attach some substances to pass. to opiate receptors. Sodium movement across the • membrane is slowed, thus slowing nerve conduction CNS depressants reduce anxiety, decrease and pain interpretation. excitability, and (at higher doses) produce sleep. Depressants include barbiturates, benzodiazepines, • Opiate analgesics act in the same manner as and alcohol. endorphins. • Depressants work by interfering with ion movement • Opiate analgesics include morphine, fentanyl, across the membrane or occupying receptor sites. codeine, and hydromorphone. Side effects include • respiratory depression, altered mental status, and Anesthesia is lack of sensation. vasodilation. • Analgesia, the fi rst stage of anesthesia, is the lack • Synthetic opiates, including meperidine and of pain. methadone, have less undesirable side effects. • Anesthetic agents can be inhaled or intravenously • Opiate antagonists, such as naloxone, reverse the administered. effects but do not affect an allergic reaction. • Nitrous oxide is an inhaled fi eld anesthetic. • Non-opioid analgesics act at the level of the injury, • IV anesthetics include short-acting benzodiazepines reducing the effects of infl ammation. and short-acting barbiturates. • Salicylate (aspirin) toxicity results in a metabolic • Conscious sedation is a technique used to depress acidosis. a patient’s level of consciousness without loss of • Acetaminophen toxicity can lead to permanent liver protective refl exes. In the fi eld setting, it enables damage. the Paramedic to perform diffi cult or painful procedures. • Anticonvulsant medications affect the sodium • channels in the nerve’s action potential or affect Pain is the most common reason to call EMS. the neurotransmitter GABA, reducing rapid • The pain threshold, the level of stimulus that will electrical discharges. Barbiturates, hydantoins, elicit a pain response, varies from person to person. benzodiazepines, succinimides, and valproic acid prevent or treat seizure activity. • Nociceptors (pain receptors) send messages over myelinated A fi bers (sharp pain) or via unmyelinated • Anti-Parkinson’s medications block acetylcholine or C fi bers (dull or burning pain). A fi bers connect to increase dopamine reception in the brain. 712 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. • The endocrine system utilizes hormones to relay (histamine) can cause bronchoconstriction, chemical messages. Hormones can be given to treat angioedema, and airway swelling, plus hypotension some endocrine diseases. secondary to vasodilation. Antihistamines are • antagonists and compete for the H1 receptors. Diabetes mellitus can cause the medical They prevent further effects but do not reverse emergencies of hypoglycemia or hyperglycemia with the effects already present. Epinephrine reverses or without acidosis. the effects. • Insulin is a protein that must be injected. Various • Gastrointestinal medications include over-the- insulin preparations have different onset and counter antacids designed to buffer stomach acids, duration of effect. emetics that induce vomiting, antiemetics that • Oral hypoglycemic agents act in one or more of the prevent vomiting by affecting the vomiting center in following ways: the brain, antidiarrheal medications, and laxatives that stimulate release of rectal contents, soften the ■ Stimulate beta cells in the pancreas to produce more insulin stool by increased water absorption, or bulk up the stool with insoluble fi bers. ■ Reduce glucagon levels ■ Increase insulin binding to cell receptors • Medications that treat bleeding disorders either ■ Delay absorption of carbohydrates interfere with anticoagulant drugs or replace ■ Lower insulin resistance missing coagulation factors. • Hypoglycemia is treated with sugar replacement • Ineffective or decreased red blood cells may be by mouth or intravenously. Glucagon can be given treated with replacement substances such as iron or intramuscularly to stimulate the release of glycogen vitamins. and its subsequent metabolism to glucose. • • Antipsychotic medications include those that block The cortex of the adrenal glands produces dopamine receptors, those that reduce anxiety, and mineralocorticoids (which affect water and sodium those that enhance the neurotransmitters, called balance), glucocorticoids (which affect infl ammation), monoamines. androgenous steroids, and estrogen. The medulla produces epinephrine and norepinephrine. • Medications that slow labor are called tocolytics. • Many work by beta agonism relaxing the smooth The ovaries are the primary site of estrogen muscle of the uterus. Medications that enhance production. Altering the amount and timing of labor (oxytocics) work by stimulating or imitating estrogen production has a contraceptive effect. the effect of oxytocin from the posterior pituitary. Estrogen also inhibits or enhances the growth of tumors, has a cardioprotective effect, and limits • Drugs used to combat infection are directed toward bone density loss in post-menopausal women. the specifi c agent. • ■ Antibiotics affect bacterial invasions through The pituitary gland produces different hormones inhibiting cell wall synthesis, inhibiting protein in its anterior portion compared to its posterior synthesis, or as an antimetabolite. portion. Antidiuretic hormone from the ■ Antivirals try to prevent viruses from invading posterior portion is given as vasopressin to cause host cells. vasoconstriction and limit water loss. Oxytocin is ■ Antifungals affect the integrity of the rigid cell also a posterior pituitary hormone. wall. • The thyroid gland is responsible for the rate of ■ Antiprotozoans and antihelmintics help the body metabolism. Drugs used to treat thyroid disorders purge the invading organisms. include medications to stimulate the production of • Drugs used to treat cancer are antineoplastics. triiodothyronine (T3) or thyroxine (T4). These affect the metabolism of the rapidly dividing • Anaphylaxis is the most severe inappropriate cancer cell but also affect other rapidly dividing response to an allergen. The chemical mediator cells such as hair follicles. Pharmacological Therapeutics for Medical Emergencies 713 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Review Questions: 1. Describe the mechanism of action of opiate 8. Name two medications given to treat pain relievers. hypoglycemia. 2. How does the opiate antagonist naloxone 9. What is the mechanism of action of work? Does it affect an allergic reaction to an antihistamines? Do these medications reverse opiate drug? the presenting signs? 3. List at least two non-opiate pain relievers, 10. Name two mechanisms of action for state their mechanism of action, and state their antipsychotic medications. What is a potentially toxic effects. reversible side effect of the major antipsychotic 4. Name two ways in which anticonvulsant agents? medications prevent or treat seizures. 11. What is the classifi cation of drugs that slow or 5. What is the mechanism of action of anti- stop labor? Stimulate labor? Parkinson’s drugs? 12. Describe three mechanisms by which 6. What protein is given to reduce glucose levels in antibiotics work. the blood? Can it be taken orally? 7. List the mechanisms used by oral hypoglycemic agents to lower blood glucose levels. Case Study Questions: Please refer to the Case Study at the beginning of the 3. Name at least fi ve questions that the Paramedic chapter and answer the questions below: should ask regarding the patient’s past medical 1. What classifi cations of drugs relieve pain? Alter history. sensation? Modify metabolism? 2. Name at least six questions the Paramedic should ask regarding the history of the present illness (complaint). References: 1. Burt A. Textbook of Neuroanatomy. Philadelphia: W.B. Saunders 5. Whitwam JG, Amrein R. Pharmacology of fl umazenil. Acta Company; 1993. Anaesthesiol Scand Suppl. 1995;108:3–14. 2. Seigel G, ed., et al. Basic Neurochemistry: Molecular, Cellular 6. Ngo AS, Anthony CR, et al. Should a benzodiazepine antagonist and Medical Aspects (Periodicals). Philadelphia: Lippincott be used in unconscious patients presenting to the emergency Williams & Wilkins; 1998. department? 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Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. 52. Reimondo G, Bovio S, et al. Secondary hypoadrenalism. 67. Au N, Rettie AE. Pharmacogenomics of 4-hydroxycoumarin Pituitary. 2008;11(2):147–154. anticoagulants. Drug Metab Rev. 2008;40(2):355–375. 53. Karagiannis A, Mikhailidis DP, et al. Pheochromocytoma: an 68. Agaliotis DP.Hemophilia overview. 2008. Available at: http:// update on genetics and management. Endocr Relat Cancer. www.emedicine.com/med/TOPIC3528.HTM. Accessed 2007;14(4):935–956. November 22, 2008. 54. Jick S, Kaye JA, et al. Further results on the risk of nonfatal 69. Dayalu P, Chou KL. 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Recent developments in the therapeutic potential of Commun. 2006;27(3):205–211. cannabinoids. P R Health Sci J. 2005;24(1):19–26. 716 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. KEY CONCEPTS: Upon completion of this chapter, it is expected that the reader will understand these following concepts: • Phases of the cardiac cycle • The coronary blood supply to the major portions of the cardiac conduction system compared and contrasted with the regions of the heart. • The heart’s pacemaking control, rate, and rhythm • The purpose of ECG monitoring • The electrophysical and hemodynamic events occurring throughout the entire cardiac cycle correlated with the various ECG waveforms, segments, and intervals Case Study: “Something just happened to Mrs. Fitzpatrick,” said the intern Paramedic. “Her ECG complexes were upright and now they are negative.” His preceptor (teaching Paramedic) asked if he changed leads, but the intern Paramedic denied doing anything to the monitor. After they had checked the patient, the preceptor began reviewing the waveforms on the ECG tracing. 718 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. FPO Principles of Electrocardiography 719 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. OVERVIEW: From the toes to the nose, the heart pumps blood throughout the entire body. Similar to the fi re engine’s water pump, the heart has two components. It has an electrical system that controls the pump’s action and a mechanical system that produces the pump’s output. In the heart, both must work effi ciently and in sequence in order to maintain the rhythmic pumping action that causes the 2 to 3 billion heart beats which occur over the average person’s lifespan. The electricity to run the heart’s electrical system results from an electrochemical process. That electrochemical process occurs in specialized nervous cells in the heart’s conduction system. This conduction system rhythmically stimulates the heart’s muscles, thereby pacing the heart. Since the heart is essential to life, the heart’s muscle cells (the myocardial cells) possess a special property called automaticity. That is, they can also generate electricity but at a much slower rate. This myocardial- induced pacing is a backup system that, although generally less effi cient, can be life-saving. The mechanical process, which creates the movement of blood and generates a pulse, is secondary to the electrical process and is dependent upon the electrical system for rate and rhythm. Damage and disruption to the electrical system can be catastrophic to the individual. Therefore, it is important for Paramedics to constantly assess the heart’s electrical activity. Technology has given Paramedics the tools to observe the heart’s electrical activity and to visually display it on an ECG monitor. Anatomy Myocardium The heart lies within the thoracic cavity, an area in the center Myocardium of the chest. This space, known as the mediastinum, also con- tains the great vessels (the aorta and the trachea). The heart is situated directly behind the sternum and extends slightly farther to the left of sternum than to the right. The base of the heart, where the great vessels enter, is located at the 2nd inter- Epicardium costal space. The apex of the heart is located at approximately (visceral layer of the the 5th intercostal space on the left midclavicular line. Endocardium serous The heart is composed of three layers of tissues pericardium) (Figure 32-1). From outside inward, the fi rst layer of the heart is the two-part pericardium. It has one part which envelops Figure 32-1 Cross-section of the myocardium. the heart and roots of the great vessels, plus another part that is closely adherent to the heart called the epicardium. The cords (such as the chordae tendinae or, as in the case of the epicardium is considered the heart’s outermost part. Between aorta, a thick supportive ring). these two parts is a lubricant called pericardial fl uid which The muscle fi bers of

the myocardium are specially decreases friction as the heart beats within the pericardial sac. arranged in vertical bundles and fi gure 8 shapes called whorls. The next layer is the thicker myocardium. The myocar- This arrangement allows maximum effi ciency in both push- dium is a muscular layer that actually performs the heart’s ing and squeezing blood out of the heart during each heart work by contracting forcefully and ejecting blood from within beat. The muscles, valves, and rings all attach to a fi brous the heart’s chambers. Controlling this ejection are valves. matrix called the cardiac skeleton. Valves serve to direct blood in one direction from one cham- The innermost layer of the heart is the endocardium. ber to another through the heart. These valves are assisted by The endocardium is a single-layer thick sheet of epithelial muscles (such as the papillary muscles) and thick connective cells that act as a lining, like the sleeve inside a fi re hose. 720 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Unlike the rest of the heart, this layer gets its nutrition (oxy- through ventricular fi lling and ejection, is called a cardiac gen and glucose) directly from the circulating blood volume. cycle. The cardiac cycle is highly dependent upon pressure Unfortunately, because of its direct contact with circulating changes that occur within the heart’s chambers to create for- blood, this layer is prone to infection from any pathogen cir- ward blood fl ow. When the atria are at rest (atrial diastole) culating in the blood (e.g., an infection such as syphilis). This blood fl ows into the atria from the body and lungs. The blood infected condition is called endocarditis. then continues into the ventricles through the open atrioven- Although cardiac muscle fi bers function similarly to tricular valves. Approximately 70% of the blood returning skeletal muscle fi bers, there are several important differences. to the heart passively enters the ventricles at this time. As A specialized cell membrane in the myocardial cell reduces pressure increases in the atria, the atria become stretched. electrical resistance and allows an electrical stimulus to move The stretched atria will then contract (atrial systole), forc- rapidly from cell to cell. The myocardial cells are found in ing approximately 32% more blood into the ventricles than strands, or myofi brils, which form an extensive interrelated would normally be there because of passive ventricular fi ll- network. This network further enhances the rapid movement ing. The active contribution of blood to the ventricle by the of the electrical stimulus from cell to cell and myofi bril to atria is called the atrial kick. This atrial kick ultimately myofi bril, as well as to the myocardial mass as a whole. This increases the amount of blood in the ventricles (the end dia- networking of cells and myofi brils allows simultaneous stim- stolic volume (EDV) or the preload). The greater the preload, ulation of the whole structure so that it functionally acts as the greater the cardiac output. a single unit. A mass of cells that act as a unit is termed a With the ventricles maximally fi lled, the backpressure functional syncytium. The atria act as one syncytium and from the blood in the ventricles causes the atrioventricular the ventricles as another. The cardiac skeleton, made up of valves to close and bulge upward toward the atria. The chor- fi brous connective tissues, serves to isolate one syncytium dae tendinae (Figure 32-2), strong cords attached to papil- from the other. As a result of electrical stimulation, muscles lary muscles, which emanate from the inferior wall, prevent in the atria will contract as a unit (a functional syncytium), the valves from inverting into the atria, which would allow pushing blood from the base of the heart to the apex of the a backfl ow of blood into the atria (regurgitation). With the heart and the ventricles. The muscular ventricles will, in atrioventricular valves closed, the atria begins diastole again turn, function as another functional syncytium, pushing and while the ventricles prepare for systole. squeezing blood from the apex of the heart and out the great As a result of the atrial kick, and because the atrioven- vessels. tricular valves are closed, the pressure within the ventricles rises sharply, distending the ventricular walls. This distention Cardiac Cycle of the ventricles, and the resulting tension, causes the myo- cardium to contract more forcibly—a phenomenon predicted During a single contraction (one heart beat), blood fl ows in Starling’s law. through all four chambers of the heart. This contraction, With the pressure elevated in the ventricles, the ventricu- including an entire sequence of events from atrial fi lling lar muscle fi bers contract forcefully and generate suffi cient Direction of blood flow Atrium Cusp of atrioventricular valve Chordae tendineae Papillary muscle Ventricle Atrioventricular valve open Figure 32-2 The chordae tendinae prevent inversion of the valves during ventricular systole. Principles of Electrocardiography 721 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. pressure to force open the aortic and pulmonary valves and source. The SA node initiates an impulse between 60 to eject blood out of the heart. This process is called ventricu- 100 times per minute. This rate is normally faster than in lar systole. The cardiac output (the volume of blood ejected any other portion of the conduction system. The SA node out of the ventricles) fl ows via the aorta to the body or to the assumes dominance as the pacemaker and is termed the pri- lungs. After the contraction, the ventricles relax and begin a mary or physiologic pacemaker of the heart. The SA node period of ventricular diastole. also has innervations from the sympathetic and the para- The arrangement of the muscle fi bers effi ciently ejects sympathetic nervous systems. The sympathetic nervous blood from the ventricles. However, even under optimal con- system increases automaticity and subsequently the rate of ditions, the ventricles cannot eject 100% of the blood from discharge. The sympathetic nervous system can therefore the ventricles. The percentage of blood pushed and squeezed cause the heart to race. Conversely, the cardiac branch of out of the heart is called the ejection fraction. Normal ejec- the vagus nerve, the 10th cranial nerve and a part of the tion fraction of blood in a healthy heart is 60% to 75% of the parasympathetic nervous system, dampens automaticity end diastolic volume (the preload).1 of the cardiac conduction system. Therefore, stimulation of the vagus nerve can cause the heart to slow down. The Conduction System parasympathetic nerve (the vagus nerve) ends at the AV The heart requires a taskmaster in order to perform its rhyth- node but the sympathetic nerves run the entire length of mical work. Although this taskmaster can be infl uenced by the conduction system from the SA node to the Purkinje other parts of the body, the heart’s primary control is its own fi bers. This is an important fact to remember when discuss- specialized cardiac cells. These cells are designed to carry on ing treatments for heart blocks. the heart’s electrical rhythm. These specialized cells are col- Once the impulse is initiated at the SA node, it spreads lectively called the conduction system (Figure 32-3). across the heart like a wavefront, depolarizing the myocar- The initial portion of the conduction system is the sinoa- dium along the way. The result of this electrical stimulation trial node (SA). This node is located just beneath the epicar- of the myocardium is that the right and left atria contract dium on the posterior wall of the right atrium near to the end immediately and nearly simultaneously (syncyctium) after of the vena cava and at the junction of the sinus of Valsalva the impulse leaves or exits the SA node. The impulse is and the atria. The SA node has fi bers which connect it to the then conducted toward the ventricles via the internodal heart’s right atrial cells. A special pathway exists for the SA pathways. The electrical signal then passes to the atrioven- node to communicate with the left atrium. This path is called tricular node (AV) located in between the atria and the Bachmann’s Bundle. ventricles. The SA cells have the ability to initiate an electri- The electrical impulse cannot normally enter the ven- cal impulse without needing stimulation from an outside tricles except by passing through the AV node. The cardiac skeleton, which serves as a framework for the heart’s valves, also electrically separates the atria from the ventricles. The signal next enters the AV node. The cells of the AV node are designed to conduct the impulse slowly. This electrical delay permits the atria to contract, thereby per- mitting maximal fi lling of the ventricles. This also allows the ventricle to receive the “atrial kick” that occurs when the atria contract. When atrial contraction is complete, the signal moves down the long strip of tissue below the Left atrium AV node connecting the atria and the ventricles, called the Sinoatrial node junctional tissues. The junctional tissues are capable of (pacemaker) Purkinje independently initiating a stimulus if the SA nodal impulse fibers should fail to depolarize them fi rst. The intrinsic rate of the Atrioventricular junctional tissue is approximately 40 to 60 bpm. Therefore, node if the SA node fails to fi re, then junction tissue at the Right AV node is the heart’s secondary pacemaker. Often junc- atrium tional rhythms produce less cardiac output because of the Purkinje fibers loss of the atrial kick that would normally occur if the SA node was the pacemaker.2 Atrioventricular When the impulse reaches the ventricle, it is conducted bundle through a wide, thick group of fi bers called the bundle of Right and left Interventricular His. The bundle of His conducts the impulse to the inter- bundle branches septum ventricular septum where it divides into the right and left bundle branches. The bundle branches lie deep within the Figure 32-3 The electrical conduction system. myocardium just above the endocardium. The left bundle 722 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. branch will further divide into an anterior branch and a pos- Coronary Circulation terior branch to adequately serve the larger, thicker left ven- and Its Relationship to Conduction tricle (Figure 32-4). With the exception of the endocardium, the heart does not uti- At the level of the ventricular cells, the bundle branches lize the blood fl owing through it for its metabolic needs. The further divide to carry the impulse along the Purkinje heart is served by a special set of arteries and veins called the fi bers. Purkinje fi bers, named after Jan E. Purkyne, con- coronary circulation. These blood vessels are called the cor- nect directly with the ventricular myocardium, allowing the onaries because they resemble a crown of thorns positioned ventricles to contract nearly simultaneously as a functional on top of the heart. The coronary arteries arise from the aorta syncytium. in an area adjacent to the aortic valve, an area called the sinus Impulse Formation of Valsalva. They are the fi rst arteries to arise from the aorta but they receive their blood fl ow last. This is because

the aor- Each part of the conduction system, from the SA node to the tic valve leafl ets occlude the coronary arteries during systole. Purkinje fi bers, is capable of initiating an electrical impulse The result is that the coronary arteries fi ll only after the aorta via automaticity. Such capability serves as a backup plan for valve has closed during diastole. the heart in the event one pacemaker fails. Should this occur, Because of the particular importance of the left ventricle, there is another pacemaker available to take its place. The when the term “wall” is used it describes the portions of the normal rate of the SA node is 60 to 100 impulses per minute. left ventricle. The walls of the left ventricle are broken down Its next closest neighbor, the AV node, can initiate impulses into the following: the inferior wall (that portion that lies next at a rate of 40 to 60 impulses per minute, while the bundle of to the diaphragm) and the anterior wall (that part of the left His initiates impulses at only 20 to 40 times per minute. The ventricle which faces forward). The anterior wall is the larg- slowest rate is that initiated in the Purkinje fi bers, which has a est part of the left ventricle and contains the greatest mass of rate of an agonizing 20 beats per minute or less. muscle in the heart (Figure 32-5). The conduction is arranged to complement the heart’s The anterior wall of the left ventricle gets its blood from the muscular action. The atrial aspect of the conduction system left coronary artery. The left main coronary artery almost imme- moves the impulse from superior to inferior just like the diately divides and gives rise to the left anterior descending contraction of the atria, which is from superior to inferior. coronary artery (LAD) and the left circumfl ex (Cx). Therefore, the upper portion of the conduction system can The LAD provides blood to the SA node, in 45% of the pop- be called the supraventricular (above the ventricles) portion. ulation, and to the majority of the muscle mass in the left Once the impulse enters the ventricles, the conduction system ventricle. Perhaps more importantly, the LAD provides the takes it inferiorly to the apex and then (via the Purkinje fi bers) blood supply to the lower portion of the conduction system, immediately back upward, resulting in an inferior to superior the bundle of His, and the three bundle branches. route. This mimics the ventricular contraction of inferior to However, the most important function of the LAD is to superior. The lower portion of the conduction system can be provide blood fl ow to the largest part of the left ventricle, its referred to as the ventricular portion. anterior wall. In fact, 60% to 70% of the blood that travels to the coronary arteries is provided to the LAD and subse- quently to the anterior wall. AV node AV junction Surface walls Area of the bundle of His Anterior (V1 to V4) Posterior wall, reciprocal changes only ( V1 to V4) Right bundle branch Left bundle branch Inferior wall Lateral wall (leads II, III, aVF) (I, aVL, V5, V6) Figure 32-4 The atrioventricular node provides a pause in electrical conduction for the impulse Figure 32-5 The anterior, lateral, and inferior traveling from the atria to the ventricles. walls of the heart. Principles of Electrocardiography 723 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. The circumfl ex coronary artery, a minor branch of the muscular contraction and those designed to initiate and carry left coronary artery, bends around to the left side of the heart impulses. In both circumstances, the activity is based on the and provides blood to the lateral wall of the left ventricle. movement of ions and the electrical changes that the ions The circumfl ex provides about 40% to 50% of the blood fl ow cause as they move. to the anterior wall, with the remainder supplied by the left The events are broken down into phases numbered from anterior descending coronary artery. 0 to 4. In a typical cardiac working cell, which is not part of The right coronary artery (RCA) serves the right atrium the specialized conduction system, the process will begin at and ventricle and the inferior portion or wall of the left ven- phase 0. A resting cardiac cell is normally negatively charged tricle, which lies on the diaphragm. In 55% of the population, on its inside. An electrical stimulus will change the perme- the RCA provides blood to the sinus node, and in 90% of the ability of the cell’s membrane by opening special channels, population it provides blood to the atrioventricular junction, allowing for the movement of sodium into the cell. The infl ux both located in the upper portion of the conduction system. of sodium is very rapid, and the process of allowing the The sinus node and atrioventricular junction are important sodium in is called fast channel response. Sodium is a cation portions of the conduction system as they control the atria () so a large amount of sodium moving into the cell will and therefore are part of the atrial kick. cause the inside to become positive. The coronary veins follow the general pattern of the Phase 1 begins when the fast sodium channels close. arteries except on the posterior wall, where an enlarged vein Chloride, an anion (), also moves into the cell during called the coronary sinus drains blood. The coronary sinus phase 1. With sodium no longer adding its positive charge drains into the vena cava at its juncture with the right atrium. to the inside of the cell, and chloride with its negative charge Other veins, called Thebesian’s veins, drain directly through moving in, the cell again becomes negative. the heart muscle into the heart chambers (Figure 32-6). Phase 2 is the plateau phase of the action potential. In phase 2 calcium, which is another cation (), leaks in slowly. Electrophysiology Calcium movement is termed “slow channel response” The heart creates an impulse via an electrochemical reaction. because of the difference in speed of movement from that of Electrophysiology describes how the heart actually initiates the sodium channels. At the same time calcium is coming in, the impulse by describing the electrochemical reactions that potassium (), another cation, is leaking out. The net change occur at the cellular level. Key to cardiac electrophysiology in electrical charge is zero and the cell remains somewhat is the action potential of each and every myocardial cell. The negative inside, but does not yet return to its resting state. term cardiac action potential is defi ned as the electrochemi- In phase 3 the slow channels (i.e., calcium movement) cal activity of the heart’s individual cells. This activity occurs shut down but potassium continues to move out of the cell somewhat differently in those cells designed for the work of very quickly. As a result, the cell becomes negatively charged. Anastomosis Aorta (junction of Left coronary vessels) artery (behind pulmonary trunk) Superior Superior vena cava vena cava Left atrium Right coronary artery Circumflex artery Great cardiac Right atrium vein Left Right ventricle ventricle Anterior Anterior Marginal artery interventricular cardiac vein artery Posterior Small cardiac Middle interventricular vein Coronary sinus cardiac vein artery Figure 32-6 The coronary circulation. 724 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. However, it does not have the same chemical makeup as it did occurs fastest in cells of the SA node and slowest in cells of when everything began at phase 0. There is too much sodium the Purkinje fi bers. The SA pacemaker cells generally depo- but not enough potassium inside the cell. While the electri- larize more times per minute and thus have a faster pacing cal charges are back to normal, the chemical makeup is not. rate, called the intrinsic rate. For SA cells, the intrinsic rate During this phase, another stimulus could trigger the cell to is 60 to 100 times per minute. depolarize. However, that depolarization would be out of sync The AV node cells would spontaneously depolarize at 40 with the rest of the cell’s repolarization–depolarization cycle. to 60 times per minute except that the SA node is faster (a Phase 4 begins with the cell actively pulling potassium concept called dominance). Impulses are being conducted back into the cell while forcefully expelling sodium. The to the AV node and cause depolarizations. The AV node is movement of these two ions is against their concentration said to be refractory, or unable to respond to a new stimu- gradients. Therefore, the cell must use energy to move these lus. It is not chemically or electrically ready to depolarize chemicals in order to achieve normalcy again. The process again and thus cannot spontaneously depolarize at its own is termed “active transport.” In this case, the movement is intrinsic rate. caused by the sodium–potassium pump powered by adeno- If the SA node were to stop sending impulses to the sine triphosphate (ATP). In phase 4 the cell’s chemical and AV node, the AV node would be electrically and chemically electrical composition is back at its baseline. This state is ready to begin its own spontaneous depolarizations. Thus, the called the resting membrane potential. The charge inside of heart would still receive regular impulses from a pacemaker the cell at this point is approximately 90 mV and is ready to cell but at a slower rate. This mechanism is called an escape be discharged or depolarized. mechanism. When a cell initially changes its charges, it is said to depo- These impulses of the slower pacemaker site (so-called larize. The process of returning to its resting state is called escape impulses) then become the heart’s dominant pace- repolarization. Phase 0 is the rapid depolarization of the cell. maker. The escape mechanism is the backup plan of the heart. Phases 1 to 4 describe the various stages of repolarization. If a faster pacemaker site fails, there is another slower one A pacemaker cell undergoes the same phases of the ready to take its place; a concept expanded on shortly. action potential (Figure 32-7), but the process differs slightly. The activities of phase 4 vary depending on time. Early in the Properties of Cardiac Cells phase, the sodium potassium pump is actively returning the cell to its predepolarization chemical state. Later in phase 4, All muscle cells have the qualities of excitability and con- a new process begins. tractibility. Cardiac muscle cells possess additional properties Pacemaker cells allow a slow movement of sodium and that specifi cally govern the heart’s activity. The fi rst of these calcium into the cell at the same time potassium is leaking out. special qualities is automaticity. This is the cell’s ability to These ion movements cause the cell to gradually become less generate its own action potential. Cardiac cells do not need an negative. At a certain point (or threshold) approximately 60 outside stimulus to depolarize. Enhanced automaticity is nor- mV, the cell spontaneously begins phase 0, the rapid depolar- mally a property of the pacemaker cardiac cells which gener- ization period. The inside charge of the pacemaker cell is not ate the stimulus in a predictable and reliable way. as negative as that of a working cell when phase 0 began. This The next special property of cardiac muscle is conduc- difference causes phase 0 to occur more slowly in the pace- tivity. Conductivity is the transmission of the electrical stim- maker cell. It

also changes the timing of phases 1 to 3. ulus from cell to cell. The myocardium’s ability to do this is There is variation in how quickly a pacemaker cell allows owed to special intercellular junctions. The rate at which the the leakage of sodium and calcium in and potassium out at stimulus is conducted varies from atrial cells to ventricular phase 4. The faster the leak, the sooner the cell begins phase 0 cells. This rate can be further modifi ed by damage to cells, (spontaneous depolarization). This translates into more depo- age changes, and drugs. larizations per minute or a faster rate. Leakage at phase 4 As is true with other muscles, the myocardium has the ability to respond to a stimulus, a property called excitabil- ity. Healthy cardiac cells respond to the stimulus generated Action Potential of Myocardial Working Cell from the pacemaker cells. When cells have been damaged by a lack of oxygen, they may respond to a much lower stimulus, ECG causing enhanced excitability. In some cases, the hypoxic mV 1 2 injured myocardial cell, for example, may even compete with 0 0 Action potential the pacemaker cells by generating spontaneous impulses via 3 abnormal automaticity.3–6 The resultant aberrant beats are 4 4 called ectopic beats (ectopic is Greek for “out of place”). –100 Inside cell Na° and Cell membrane The fi nal special property is the cardiac cells’s ability K° Na° Ca° K° K° K° Outside cell to contract. Contractility is the cardiac muscle fi bers’ abil- ity to shorten or contract. This is the mechanical response Figure 32-7 Cardiac cell action potentials. to the electrochemical properties of automaticity, excitability, Principles of Electrocardiography 725 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Transmembrane potential and conductivity. In order to have a heart beat as opposed to can indicate a number of abnormal cardiac and extra-cardiac electrical activity, the cardiac cells must be able to contract. conditions, it may also be normal while the patient is in jeop- Without the contraction, a state of electromechanical disso- ardy. The fi rst rule of patient care is: Treat the patient, not the ciation occurs. monitor. Electrocardiographic Principles Leads The ECG machine creates leads. A lead is a view of the Assessment of the heart’s electrical activity forms a basis for heart’s electrical activity from a specifi c vantage point. The cardiac physical assessment. The tools to assess the electrical lead relies on an electrical difference between two elec- activity have been developed over the past 200 years. However, trodes to create a view of the passage of electricity down it is only within the last 50 years that portable equipment has the heart’s conduction system over a period of time; under- been developed allowing for the out-of-hospital monitoring standing this last statement is critical for an understanding of of cardiac electrical activity. electrocardiology. Electrical current in a resting heart was fi rst measured A lead is made up of two electrodes—one electrode is in 1843, DuBois-Raymond then coined the term “action negative and the other is positive. Electricity travels from a potential” based on these measurements. Electrical changes negative electrode toward a positive electrode. As a result associated with a beating heart were fi rst recorded in 1887. of having two electrical polarities—positive and negative— Willem Einthoven developed methods of standardizing and with a distance between the two poles, a dipole is established. calibrating recordings of the electrical activity in 1911 and Because it takes some time, even though it is a fraction of built the fi rst functional ECG machine. Willem Einthoven a second, for the electricity to fl ow between one pole to the was awarded the Nobel Prize in medicine in 1924 for his other, Paramedics are able to determine its direction (vec- contributions.7 tor). Any electrical activity which fl ows toward the positive electrode will be seen as upright or positive defl ection on the ECG monitor screen or recording paper. Any activity travel- Street Smart ing away from the positive electrode will be seen as down- ward or negative defl ection (Figure 32-8). Willem Einthoven’s invention was originally called Standard Leads the “elektrokardiogramm” or EKG. The anglicized Einthoven developed recordings of the heart’s electrical activ- version of the same term is electrocardiogram ity, using both arms and the left leg as electrode placement or ECG. However, the two terms are often used interchangeably. Depolarization Electrode ECG deflection Wave By understanding the concept of syncytium and with + A knowledge of anatomy, the Paramedic knows that electricity _ + propagates (fl ows) down the heart in an activation wavefront. It moves from inside to outside (endocardium to epicardium) + _ and from base to apex to base. The resulting voltage changes + B within the heart are transmitted to the skin. Einthoven’s ECG machine is used to detect the voltage changes that occur between two points on the skin’s surface. These changes _ + + are created by the propagating activation front of the heart’s C depolarization. + The ECG machine, or monitor, records the ECG on a type of graph paper to plot the amount of change or ampli- _ tude on the vertical axis of the graph and time on the hori- D + zontal axis. These recordings are explained more fully in + Chapter 33. Observation and research has shown the norms Electrode for the amplitude/time of the surface ECG. A Paramedic with knowledge of the standard ECG trac- Figure 32-8 A positive defl ection is recorded ings can perform a comparative analysis with abnormal ECG when current is moving toward the unipolar lead tracings and relate those fi ndings to the patient’s clinical and negative when current is moving away from condition. It is important to remember that while the ECG the unipolar lead. 726 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. pathway. Defl ections from baseline are upright—larger than in Lead I but not as large as those in Lead II. Under normal conditions, the largest and clearest picture Right arm Left arm of the electrical signal is seen in Lead II. For this reason, electrode electrode (aVR) (aVL) Lead II is the single best lead to monitor the conduction path- Lead I way of the heart for errors. Waves In order for Paramedics to interpret, describe, and discuss the tracings that occur on the ECG machine due to the Right leg electrode Left leg heart’s electrical activity, a common language is needed. If electrode the Paramedic understands that during diastole the heart’s (aVF) resting membrane potential is negative (approximately () Lead Right arm Right leg Left leg Left arm 90 mV) and accepts that as a baseline, and at the moment of I – + depolarization the transmembrane potential becomes posi- tive behind the wavefront, then the Paramedic is able to trace II – + the path of the electricity cascading over the heart. Einthoven III + – described these defl ections away from the even baseline, or aVR + – – – fl atline, and termed them “waves.” If the depolarization front is moving toward the positive electrode, then its wave will aVL – – – + be upright or positive. If it is moving away from the posi- aVF – – + – tive electrode, then its wave will be downward or negative. Einthoven documented the expected changes in voltage and Figure 32-9 Einthoven’s Triangle derived assigned the waves letter titles beginning with P-Q-R-S-T-U from the standard limb ECG leads. (Table 32-1). In a healthy heart, these waves are directed toward or away from the positive electrode in a predictable manner as they pass along the heart’s conductive pathway. points (Figure 32-9). Using a human silhouette as back- To establish a baseline, the ECG tracing starts when the ground, draw a triangle extending from the left arm at the heart is at rest (diastole) and the transmembrane potential is wrist, right arm at the wrist, and left leg at the ankle. This is negative. The fl at line seen during this period, called the iso- Einthoven’s Triangle. Einthoven’s Triangle visually describes electric line, indicates that the line is not a voltage change the relationship of any two electrode points to any other two occurring. electrode points in the triangle. While not quite an equilat- When the SA node spontaneously depolarizes, it propa- eral triangle, anatomically the two leads are in an equilateral gates a wavefront across the atria that takes approximately triangular arrangement electrically. Einthoven called these 0.08 to 0.1 seconds. This is represented on the surface ECG standard leads and identifi ed them with the Roman numbers in Lead II as a rounded positive defl ection in the normal heart. of I, II, and III. The wavefront now enters the AV node where it is slowed. Lead I measures the voltage change between the right The period of time when the wavefront is retarded, in the arm and the left arm. The negative electrode is on the right electrical sense, in the AV node is seen as a brief isoelectric arm. The positive electrode is on the left arm. The axis of line on the ECG. Lead I is across the chest wall and somewhat corresponds to Exiting the AV node, the depolarization wave continues that of the conduction which occurs leftward and downward. to propagate across the entire ventricular mass in a predict- Under normal conditions, the electrical movement is toward able fashion, The fi rst area to be depolarized, from right to the positive electrode. Defl ections from baseline in Lead I are left, is the septal wall. This momentary swing in the vector generally upright or positive but small. of the electrical fl ow away from the positive electrode in Lead II notes the change between the right arm and left Lead II causes a small negative defl ection in the ECG called a leg. The positive electrode is located on the left leg. This Q wave. Not every depolarization of septal wall results in a arrangement mimics the conduction system alignment of left Q wave in every lead; sometimes the energy is too small to and downward. This arrangement is almost in-line with the be recorded. heart’s natural conductive pathway. As a result, the defl ec- Having transversed the septum, and the bundle of His tions from baseline in Lead II are upright and much larger within, to the apex of the heart, the activation front begins to than in Lead I. depolarize the myocardium in the apex of the heart toward the Lead III measures change between the left arm and left base of the heart and from the inner endocardium to the outer leg. The positive electrode is on the left leg. The axis is also epicardium. This causes a contraction of the left ventricular similar to that of Lead II and the heart’s natural conduction myocardial whorl and starts the ejection of blood from the Principles of Electrocardiography 727 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Lead III Lea d II Table 32-1 Waves on ECG with a Sinus Rhythm by a mirror image of the QRS, it does not occur in this man- in Lead

II 0 ner. The epicardium repolarizes more rapidly than the inner Name Description bundles of the endocardium, resulting in a near simultane- ous repolarization. This is represented on the ECG as a T Isoelectric line Straight line wave. Represents diastole For the sake of completeness, it is necessary to discuss No voltage difference noted the repolarization of the atria as well. Like the ventricles, Neither (1) nor (–) defl ections the atria’s repolarization is represented by a small positive P wave First defl ection from isoelectric line rounded wave called the tP wave. Under normal circum- stances, the tP wave is obscured on the ECG by the QRS. Represents atrial depolarization However, the tP may be visible during periods of ventricu- Occurs just prior to atrial contraction lar standstill. Practically, differentiating the P wave from the Positive upright and rounded tP wave under those conditions is diffi cult. However, it is pT wave Normally obscured by the QRS assumed that the fi rst wave after the longer period of diastole Represents atrial repolarization is the P wave and therefore the wave immediately following If seen, positive and upright the P wave is the tP wave. On rare occasion there may be another small positive Q wave First defl ection of the QRS complex rounded wave that occurs immediately after the T wave Represents septal depolarization and before the next cardiac cycle. Originally thought to be Downward or negative defl ection caused by a late repolarization of the Purkinje fi bers, it is now Less than one third of the total QRS height thought to be “after-depolarizations.” After-depolarizations May not occur in healthy heart are late depolarizations in the myocardium that occur as a result of altered chemistry (e.g., secondary to drugs) at the R wave Initial or second wave of the QRS complex cellular level that changes the myocardial cell’s automatic- Represents depolarization of bundle of His ity. These errors in automaticity can lead to abnormal or Upright or positive defl ection ectopic beats as a result of stimulating the rest of the myo- Is the initial wave if there is no Q wave cardium during phase 3 or phase 4 of repolarization. These S wave Final wave of QRS complex premature depolarizations of the rest of the myocardium Represents depolarization of the bundle branches can lead to triggered activity such as atrial or ventricular tachycardia. Negative or downward defl ection ECG waves combine in predictable ways to describe T wave Defl ection from baseline ventricular other cardiac events and are the basis for ECG interpretation, Represents repolarization of the ventricle discussed in further detail in Chapter 33. Positive or upright in defl ection QRS complexes are a combination of two or more U wave Small defl ection following after the T wave waves. When a wave repeats itself (e.g., there are two upward defl ections in the QRS, due to errors of condution), then the Represents after-polarizations fi rst wave is considered the prime wave and is represented Positive or upright in defl ection by a capital letter and the second wave is represented by a Not typically seen lowercase letter. For example, a proper notation of a QRS might read RSr. ventricles. The vector of this electrical wavefront down the Intervals and Spaces bundle branches is parallel to the positive lead in Lead II and In some instances, the activity between the waves (i.e., the results in a large positive defl ection on the ECG called the timing) is more representative of cardiac pathology than R wave. the waves themselves. The space between waves is called Following from the bundle branches along the Purkinje a segment and a segment and a wave together are called fi bers, the wavefront continues to propagate to its terminus an interval. Intervals and segments represent electro- in the remaining ventricular myocardium upwards toward physiological events as well as mechanical events within the base of the heart. This abrupt change in the vector of the the heart. wavefront away from the positive lead in Lead II creates a The fi rst interval on the standard ECG is the PR i nterval. negative defl ection that is represented by the S wave. The PR interval represents the retardation of the propaga- Following the depolarization of the ventricular myocar- tion of the depolarization in the atrioventricular node. dium, the heart immediately begins the process of repolar- Normally this interval is a fraction of a second, between ization. Interestingly, while it would seem the repolarization 0.12 and 0.20 seconds, and is measured from the begin- would occur in a retrograde fashion, and thus be represented ning of the P wave to the fi rst defl ection in the QRS. During 728 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. this fraction of a second, atrial kick occurs and maximal approximately the same length as the QRS (0.08 to 0.12 sec- v entricular fi lling occurs. onds) and corresponds with the plateau phase of the action If the PR interval is shortened, it may be indicative of an potential. Therefore, any alteration of the action potential accessory pathway and may lead to pre-excitation syndrome. (e.g., ischemia or drugs such as digitalis) can result in changes Alternatively, a prolonged PR interval (greater than 0.20 sec- in the ST segment. onds) may represent the initial electrophysiologic change The last segment, the TP segment, represents the time of an ischemic AV node that can progress to heart block. when phase 4 of the action potential has occurred and the However, some prolonged PR intervals are a function of the heart has achieved its resting membrane potential. Normally natural changes of aging or a drug effect. In every case, the this results in no electrical movement and is represented by patient’s medical condition must be taken into account when an isoelectric line (Table 32-2 and Figure 32-10). there is a fi nding of an abnormal PR interval. The other interval in the ECG is the QT interval. Whereas Table 32-2 Intervals and Segments the PR interval is indicative of the atrial depolarization and repolarization, the QT interval is indicative of the ventricu- Name Description Signifi cance lar depolarization–repolarization cycle. The QT interval can PR interval P wave plus PR segment Period of time for stimulus also be thought of as indicative of systole. The QT interval to travel across the atria is measured from the fi rst defl ection of the QRS to the end and delay at AV node of the T wave and is normally about 0.40 seconds. However, ST segment Point from J wave to T Beginning of ventricular QT intervals vary according to the heart’s rate. The faster a wave repolarization heart races, the shorter the QT interval becomes. To ascertain QT interval Beginning of QRS Represents ventricular if a QT interval is abnormal, the heart rate must be taken into complex to end of T depolarization and account. Using Bazett’s formula, the measurement is cor- wave repolarization rected to account for the increased automaticity. The result TP segment Point from end of T Represents the isoelectric is referred to as the QT corrected or QTc. Any QT interval wave to start of next line greater than 0.44 seconds is considered abnormal and labeled depolarization a “prolonged QT interval.” Medications, such as Vaughn-Williams Class I drugs, can cause a prolonged QT interval as well as a congenital condition called prolonged QT syndrome (LQTS). Patients ECG intervals with LQTS are prone to ventricular tachycardias—particularly one dysrhythmia called polymorphic ventricular tachycardia or torsades de pointes.8–10 Conversely, some patients may be born with short QT syndrome. Short QT syndrome (less than 0.32 seconds) is the cause of syncope and sudden cardiac death as well. Perhaps the most important segment or interval is the ST ST segment. The ST segment, that period from the end of P segment T the QRS to the beginning of the T wave, represents an iso- 0.08 to < 0.12 < 0.20 electric period in the normal heart; a time when the heart is 0.11 sec sec sec neither depolarizing or repolarizing In the ischemic heart, where there is altered electrophysiology, late depolarization may cause either a depression or an elevation in the ST seg- PR interval Q R S ment. In some cases, the ST segment elevation may represent myocardial infarction in progress, known as an ST elevation 0.12 to < 0.10 sec myocardial infarction (STEMI); more discussions of this 0.20 sec very important ECG fi nding are contained in the following QT interval chapters. < 0.38 sec The ST segment starts at the J point, the point imme- diately following the QRS where the ECG returns to base- Time line and continues to the T wave. The typical ST segment is Figure 32-10 ECG complex intervals. Principles of Electrocardiography 729 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Voltage The measurement of the heart’s electrical activity is a key objective assessment tool for the Paramedic. This chapter has provided a basis for the heart’s electrophysiology and lays the foundation for the following two chapters that discuss monitoring of the cardiac rhythm and 12-lead ECG. Key points: • The heart lies within the thoracic cavity. The base connect it to the heart’s atrial cells. of the heart is located at the 2nd intercostal space A special pathway exists to communicate with and the apex is located at approximately the 5th the left atrium. This path is called Bachmann’s intercostal space on the left midclavicular line. Bundle. The impulse is also conducted toward The heart is composed of three layers. First is the the ventricles via the internodal pathways to the two-part pericardium which envelops the heart atrioventricular node (AV). When the impulse and roots of the great vessels plus continues on as reaches the ventricular side of the AV node, it is the epicardium, or outermost layer of the heart. conducted through a wide, thick group of fi bers The next layer, closer to the center of the organ, called the bundle of His, which divides into the is the myocardium. This is the muscular layer. The right and left bundle branches. The left bundle innermost layer is the endocardium, which lines the branch will further divide into an anterior branch chambers of the heart. Valves serve to direct blood and a posterior branch to adequately serve the in one direction through the heart. larger, thicker left ventricle. At the level of the ventricular cells, the impulse is carried by the • An entire sequence of events from atrial fi lling and Purkinje fi bers. ejection through ventricular fi lling and ejection is called the cardiac cycle. The cycle consists of atrial • The heart’s rate and rhythm are initiated and diastole and systole plus ventricular diastole and controlled by an electrochemical process. Altering systole. the ion content inside of a pacemaking cell triggers • an electrical stimulus. The SA node completes this The heart is served by a special set of arteries and process more quickly than any part of a healthy veins called the coronary circulation. The major conduction system and is therefore considered coronary arteries are the right coronary artery the heart’s pacemaker. The number of times per (RCA) and the left coronary artery (LCA, also called minute that the SA node completes this process is the left main) which divides into the left anterior termed its intrinsic rate. Should the SA node fail, descending artery (LAD) and the left circumfl ex the AV node has a slower intrinsic rate and will act artery

(LCx). as the backup plan or escape pacemaker. Should • In 55% of the population, the RCA provides blood the AV node fail, the bundle of His or Purkinje to the sinus node. In 90% of the population, it fi bers can function as an escape pacemaker, provides blood to the atrioventricular junction. although at a much slower rate. The LAD provides blood to the SA node in the remaining 45% of the population, to the AV junction • The action potential has fi ve phases numbered in the remaining 10% of the population, and to the 0 to 4. remainder of the conduction system in nearly 100% ■ In phase 0, a resting cardiac cell is normally of people. negatively charged on its inside. A rapid infl ux of sodium occurs, causing the inside to become • The initial portion of the conduction system is the positive. sinoatrial node (SA). The SA node has fi bers which 730 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. ■ Phase 1 begins when the fast sodium channels as a unit from superior to inferior. The ventricles close. Chloride, an anion (), moves into the will function as a unit, pushing and squeezing blood cell. With its negative charge, the cell again from inferior to superior. becomes negative. ■ Phase 2 is a plateau phase. Calcium (another • The electrical impulse cannot normally enter the cation) leaks in slowly. At the same time calcium ventricles except by passing through the AV node. is coming in, potassium (another cation) is The cells of the AV node are designed to conduct the leaking out. The net change in electrical charge impulse slowly, which allows the ventricles to receive is zero and the cell remains somewhat negative the “atrial kick” that occurs when the atria contract. inside, but does not yet return to its resting • The functional properties of cardiac muscle tissue state. are automaticity, excitability, conductivity, and ■ Phase 3 has the slow channels or calcium contractility. movement shut down, although potassium moves out of the cell very quickly. The cell • Using electrodes, the ECG records the voltage becomes very negative but does not have the changes that occur between two points and are same chemical makeup as it did when everything transmitted to the skin. began at phase 0. ■ Phase 4 begins with the cell actively pulling • Electricity travels from a negative point toward a potassium back into the cell while forcefully positive one. The positive electrode is the viewing expelling sodium. electrode. Any electrical activity that points toward the positive electrode will be seen as upright • Cardiac muscle fi bers have a specialized cell or positive on the screen or paper. Any activity membrane that reduces electrical resistance traveling away from the positive electrode will be and allows an electrical stimulus to move rapidly seen as downward or negative. from cell to cell. The cells also form an extensive network that further enhances the rapid movement • The waves evident on the ECG correspond to of the electrical stimulus. This allows the whole electrical events in the body. structure to act as a unit. The atria will contract Review Questions: 1. If a papillary muscle in the right ventricle was properties, describe how the heart’s normal damaged and did not function, what could processes can be disrupted. happen to forward blood fl ow? 5. Would it be possible for the properties of 2. Name two ways in which a very rapid heart rate automaticity, excitability, and conductivity to may interfere with coronary blood fl ow. function but not the property of contractility? 3. Describe what may occur if a person had an Why or why not? What assessment would give accessory pathway around the AV node. you the answer? 4. When heart cells die, they are replaced by 6. If you could design a substance that would slow scar tissue. The scar tissue does not possess the movement of calcium into the cell at the properties of automaticity, conductivity, phase 2 of the cardiac action potential, what excitability, or contractility. Using each of these would happen to the heart rate? Principles of Electrocardiography 731 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Case Study Questions: Please refer to the Case Study at the beginning of the 3. Where is the electrical stimulus when each of chapter and answer the questions below: the following waves, intervals, segments, or 1. Why did the Paramedics check the patient before complexes is occurring? analyzing the monitoring strip? a. P wave 2. What is happening at the cellular level when b. PR interval each of the following waves, intervals, segments, c. QRS complex or complexes is occurring? d. ST segment a. P wave e. T wave b. PR interval 4. What is happening mechanically during c. QRS complex a. the P wave? d. ST segment b. the QRS complex? e. T wave c. the T wave? References: 1. Wayne- Alexander R, Fuster V, King SB, Nash I, O’Rourke RA, 6. Kaminski KA, Bonda TA, Korecki J, Musial WJ. Oxidative Prystowsky EN, Roberts R. Hurst’s the Heart, Vol. 2 (11th ed.). stress and neutrophil activation—the two keystones of ischemia/ New York: McGraw-Hill Professional; 2005. reperfusion injury. Int J Cardiol. 2002;86(1):41–59. 2. Brunekreeft JA, Graauw M, de Milliano PA, Keijer JT. Infl uence 7. Cajavilca C, Varon J. Willem Einthoven: the development of the of left bundle branch block on left ventricular volumes, ejection human electrocardiogram. Resuscitation. 2007;76(3):325–328. fraction and regional wall motion. Neth Heart J. 2007;15(3):89–94. 8. Roden DM. Clinical practice. Long-QT syndrome. N Engl J Med. 3. Sarre A, Maury P, Kucera P, Kappenberger L, Raddatz E. 2008;358(2):169–176. Arrhythmogenesis in the developing heart during 9. Janeira LF. Torsades de pointes and long QT syndromes. Am Fam anoxia-reoxygenation and hypothermia-rewarming: an in vitro Physician. 1995;52(5):1447–1453. model. J Cardiovasc Electrophysiol. 2006;17(12):1350–1359. 10. Kannankeril PJ, Roden DM. Drug-induced long QT and torsade 4. Kutala VK, Khan M, Angelos MG, Kuppusamy P. Role of oxygen de pointes: recent advances. Curr Opin Cardiol. 2007;22(1): in postischemic myocardial injury. Antioxid Redox Signal. 39–43. 2007;9(8):1193–1206. 5. Hoffman JW, Jr., Gilbert TB, Poston RS, Silldorff EP. Myocardial reperfusion injury: etiology, mechanisms, and therapies. J Extra Corpor Technol. 2004;36(4):391–411. 732 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. KEY CONCEPTS: Upon completion of this chapter, it is expected that the reader will understand these following concepts: • Use of ECG as a tool • Correct application of electrodes • Troubleshooting the equipment • Interpretation of rhythms Case Study: Jane Sheehan had called EMS because she felt faint and her heart seemed to be beating too fast. The fi rst response unit had started her on oxygen, obtained vital signs, and was asking questions about the event when the Paramedic unit arrived. The Paramedic received report while placing Ms. Sheehan on a cardiac monitor. The Paramedic quickly interpreted the rhythm, verifi ed that Ms. Sheehan did not have any drug allergies, and then outlined a plan of care for her. The EMTs wondered aloud what the lines on the monitor meant and what part they played in determining a diagnosis and treatment. 734 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. FPO The Monitoring ECG 735 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. OVERVIEW: Paramedics use an electrocardiogram each day to monitor the cardiac rhythm in a signifi cant proportion of their patients. Most cardiac monitors today have developed into comprehensive monitoring tools that measure other parameters including blood pressure, pulse oximetry, and capnography. In this chapter, we will examine the use of the basic cardiac monitor to observe the patient’s cardiac rhythm. The Monitoring ECG In the eyes of the public and many healthcare providers, the distinction between basic life support and advanced life sup- port is the electrocardiogram machine. The electrocardio- gram (ECG) provides Paramedics with information about the electrical activity of the patient’s heart (i.e., the depolariza- tion and repolarization of the heart through the cardiac cycle of systole and diastole). Armed with this additional data, the Paramedic can make better clinical decisions regarding treat- ment and transport. By interpreting the ECG’s rhythm for disorder, the Paramedic can come to suspect electrolyte disturbances that can cause errors of automaticity (conduction abnormalities) or errors of conduction, as well as signs of is-chemic heart disease. Any of these can indicate a potent ial life-t hreatening Figure 33-1 A Paramedic’s cardiac emergency. Furthermore, changes in a rhythm strip may be monitor–defi brillator. indicative of other medical conditions such as head injury, toxic exposure, electrolyte imbalance or other more funda- mental disorders such as hypoxia and hypothermia.1 Continuous monitoring of the patient’s heart rhythm monitor (Figure 33-1). The monitor is analogous to a com- allows the Paramedic to note changes in the patient’s con- puter’s visual display of the machine’s output. dition, as well as the patient’s response to treatments, and thus continue or alter treatment plans accordingly. The ECG Tracing goal of prehospital ECG monitoring is to obtain a clear and Like the original silver string galvanometer used in the accurate view of the heart’s electrical activity quickly and fi rst experiments by Willem Einthoven, the modern ECG dependably. machine senses the current changes, or fl uctuations, between When using an ECG, the Paramedic’s fi rst priority two e lectrodes—one negative and one positive—as a wave should be to monitor the heart for the presence of any life- of depolarization cascades down the heart and displays that t hreatening dysrhythmia. The utilization of a diagnostic information on a screen.2,3 A downward defl ection indicates 12-lead ECG always comes after the patient’s initial rhythm that the electricity is fl owing away from a positive, or moni- has been confi rmed. toring, electrode. An upward defl ection indicates that the depolarization wave is fl owing toward a positive monitoring Portable ECG Equipment electrode. If the differences in the fl ow of electricity resulted Portable ECG equipment consists of an oscilloscope and a in a zero

net difference in direction (i.e., electricity was fl ow- printer needed to review and record ECG. The original oscil- ing both toward and away from the positive electrode (per- loscopes on an ECG machine operated similar to the fi rst pendicular) at the same time), then the resulting signal is television sets. A beam of electrons struck a phosphorescent equiphasic or fl atline. screen and produced a point of light. Slight differences in Using this technology, the movement of electricity voltages cause movement of the beam, which is displayed within the body could be observed, by the bounce of a point on the screen as fl uctuations in the point of light. The point of light, at any given moment. However, the fl ow of elec- of light could be seen to move either as an upward spike (a tricity within the heart as it travels down a conductive path- positive defl ection) or in a downward defl ection (a nega- way takes time. Therefore, the dimension of time must be tive spike). The ECG oscilloscope is also called a cardiac included if the meter is to illustrate the passage of electricity 736 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. down the conduction pathway. Oscilloscopes can add the indicates the passage of an ECG complex across the monitor. dimension of time by moving the point of light across the The volume of these counters can be adjusted, or shut off, to screen from left to right at a precise rate of speed. Speed is reduce noise pollution on scene. distance over time and is measured in fractions of a second The purpose of an ECG monitor is to alert the Paramedic in the heart. to potentially life-threatening dysrhythmias. To that end, Compared against a static grid placed over the oscil- some ECG monitors have alarms that will indicate, via vis- loscope, this horizontal left-to-right movement (manifested ible and/or audible signal, that a patient’s heart rate is above on the screen as a trace) can be measured and fl uctuations or below a certain rate. The Paramedic often has the option expressed in terms of time (seconds or milliseconds). Any of choosing the rate values (called the alarm limits) accord- vertical fl uctuations seen on the monitor can also be mea- ing to the patient circumstances. Some EMS agencies do sured. Vertical fl uctuations represent the voltage change from not permit Paramedics to alter alarm limits or to disable zero, either positive or negative. The change from zero can alarms. This fail-safe device offers another level of secu- also be measured on a grid and is expressed in terms of mil- rity to permit early detection of potentially life-threatening livolts (mV). The larger the voltage difference, the larger the dysrhythmias. fl uctuation. Finally, an additional feature on some ECG monitors Current ECG monitors not only measure the energy and is an ability to adjust the brilliance of the ECG monitor. the speed of conduction, but they also have many other fea- Depending on ambient light conditions, it may be desirable tures that are valuable to the Paramedic. to turn up the brilliance of the ECG monitor or to dampen it in order to improve the quality of the ECG. Monitor Features The standard ECG monitor typically features a sensitivity Monitor Adjustments and sweep speed control, output printer, lead selector, rate Many monitors permit the Paramedic to adjust certain vari- counter, monitor brightness control, and alarms. Many ECG ables in order to improve the ECG tracing’s usefulness. For monitors also have telemetry capabilities. Telemetry is the example, most monitors available to the Paramedic allow a ability to broadcast the ECG via telephone or radio to a dis- tant receiver, typically located at a hospital.4–6 change in speed and amplitude of a tracing. The Paramedic may want to change the speed of the rhythm passing by on the To make the ECG readable, the ECG monitor must have screen. An alteration in the speed of the tracing is an altera- both a sweep speed control and a sensitivity control. The tion in sweep speed. Standard sweep speed is 25 mm/second. sweep speed control regulates the speed of the tracing on the Increasing the sweep speed to 50 mm/second will stretch out monitor, and subsequently on the printout. The sensitivity the trace and make the trace appear slower than it actually control alters the size of the ECG tracing. Adjusting these is. However, slowing sweep speed will also allow for closer functions on the ECG monitor provides the Paramedic with examination of key features on the ECG, such as changes in some advantages in certain clinical situations. the segments or minor defl ections in the QRS. To facilitate analysis, and documentation, a printer was The Paramedic may need to also enlarge the tracing added to print out the ECG seen on the screen. The printer shown on the monitor. This is called increasing the gain. The provides a printed hard copy of the ECG tracing visible on gain increases the size of the tracing shown on the monitor the ECG monitor. In many cases manufacturers have built in screen. Occasionally key features of the ECG are too small for a 5- to 10-second delay between what is visible on the ECG clear examination without increasing the gain. By adjusting monitor and what is being printed out. This momentary delay the gain, the Paramedic can get a clearer picture. Conditions permits the Paramedic time to activate the printer if an irregu- which can cause low amplitude include a variety of medical larity in rhythm is seen on the ECG monitor and thus capture conditions (Table 33-1). the dysrythmia. In some instances one view, or lead, is better than another when trying to make an ECG interpretation. Lead selection Calibration (changing the electrical view of the heart without moving The ECG monitor is a medical device. As such, Paramedics electrodes) permits the Paramedic an opportunity to observe should regularly ensure that the ECG monitor is accurate. Any the heart from several angles at an instant. Optional leads and number of medical interventions may be performed, includ- lead selection are discussed shortly. ing defi brillation and medication administration, based in An added feature of many ECG monitors is the rate large part upon the ECG tracing. A faulty ECG monitor could counter. The rate counter is a digital readout of the number lead to an error of treatment. For this reason an ECG monitor of ECG complexes that pass in a minute, usually counting should regularly serviced by a biomedical engineer who will the tallest, or deepest, wave on the ECG. Some ECG moni- re-calibrate the ECG monitor to factory specifi cations. tors also have a fl ashing light, or other visible signal, that On a daily basis, and to assess accuracy of the ECG moni- indicates when an ECG complex has passed across a point on tor, the Paramedic compares the ECG machine’s operation the monitor. Some rate counters have an audible signal which against standard settings (i.e., industry standards). Making The Monitoring ECG 737 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Table 33-1 Conditions That May Cause ECG standardization a Low-Amplitude ECG STD 1 • Amyloidosis—deposits of proteinaceous mass in muscle fi bers • Hypothyroidism (a.k.a. myxedema) • Restrictive cardiomyopathy  Endomyocardial fi brosis • Pericardial effusions  Hemopericardium 1 mV = 10 mm  Infectious transudate • Pericardial tamponade • Tension pneumothorax • Obesity FULL • Hypothermia 0.04 sec sure that sweep speed and gain is up to standard is called cali- bration. Most ECG monitors self-calibrate, internally setting Figure 33-2 Normal standardized standard sweep speeds and gain, when initially switched on. calibration mark. However, many ECG monitors also provide an internal user test that allows the paramedic to check calibration and operational readiness at the beginning of the shift; many Paramedic services require that the Paramedic document that calibration test The calibration mark (Figure 33-2), visible at the begin- ning of the ECG printout, is a square wave that is 10 mm high, or 1 mV, and 10 mm wide. Each box measures 0.1 mV vertically and 0.4 mm horizontally. The calibration mark is created by a calibration impulse, an electric impulse, by the ECG machine. The resulting wave should be sharply delin- eated (i.e., quick corners that make a squared wave). ECG Paper Reading an ECG on the monitor can be diffi cult at times. Therefore, a hard copy can improve the accuracy of the analy- sis. For this reason, most Paramedics print out a copy of the 0.04 second ECG, called an ECG rhythm strip. The paper used for ECG 0.1 mV recordings is imprinted on heat-sensitive paper via heated 1 mm stylus or is printed by a laser. It is lined in a manner similar to graph paper to enable a Paramedic to accurately measure and compare ECG waves. In order to determine regularity, rate, timing, and ampli- Figure 33-3 The standard ECG graph. tude of the ECG features, the Paramedic must understand the grid structure of ECG paper. The paper is lined vertically and horizontally (Figure 33-3). On the vertical axis, a line occurs amplitude, which can be roughly equated to the strength of every 1 mm and a darker line occurs every 5 mm. For the the electrical signal. horizontal axis, a line occurs every 0.04 seconds and a darker line every 0.20 seconds. The amplitude markings are correct Wire Systems assuming there is a standard gain of 10 mm/mV, and the time The wiring harness, also called the ECG cable, connects the markings are correct assuming a standard sweep speed of electrodes to the ECG monitor and is a single thick cable that 25 mm/second. separates into three, four, or fi ve thinner wires. (Some har- When assessing the rate of a rhythm or the time frame of nesses will have an additional port that will accept a six-wire a feature on the ECG, the Paramedic will use the horizontal plug to enable the acquisition of a 12-lead ECG.) markings. The horizontal axis equals time (0.20 seconds per The machine end of the harness has a pin connector that large square). When measuring the amplitude of a feature, the must be set fi rmly into its socket in order to avoid a poor con- Paramedic will use the vertical axis. The vertical axis equals nection, which will create an unreadable signal. The thinner 738 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. wires are connected to electrodes at the distal end. These, in turn, are placed on the patient. (–) (–+ ) Electrodes For a surface ECG, the electricity must pass from the heart (+) and up through the skin in order for the ECG to detect the current. The stratum corneum, the outermost layer of the skin, A Lead I does not conduct electricity well because it contains dead and dried out cells. These dead cells cause the skin to act as a resistor; resistance to the passage of electricity.7 To permit the passage of the electrical current through the skin to the (+) (–+ ) (–) ( –+ ) surface,

the electrode must have an intermediate substance, a conductive medium which bridges the stratum corneum and connects the inside of the body with the electrode. (+) Typically an ECG electrode is used for that purpose. An (+) electrode consists of a gel-like substance that conducts elec- B Lead II C Lead III tricity well, such as silver chloride, with an adhesive on a foam or paper backing to help maintain contact (Figure 33-4). The conductive gel is designed to melt with body warmth Figure 33-5 Electrode position affects the and soak through the skin. This will enable it to overcome electrical view of the heart. skin resistance to the electrical signal and create an electrical bridge from the inside of the body to the electrode. A sticky Electrode Placement piece of foam or paper surrounds the gel. This serves to iso- late the electrode from the surrounding environment and The primary objective of monitoring the electrical activity enables the electrode to adhere closely to the skin. of a patient’s heart is to discern abnormalities of conduction Warmth is necessary for the electrode to function. or automaticity that produce potentially life-threatening dys- Without warmth the conductive gel does not melt, the electri- rhythmias. An ECG lead is a view of the heart from one par- cal pathway is ineffective, and the signal quality will be poor ticular vantage point that helps to ascertain the dysrhythmia or lost entirely. When the gel only partially melts, due to cold (Figure 33-5). For example, Lead II (a commonly used moni- skin or poor adherence of the electrode, then the quality of toring lead) views the inferior portion of the heart and would signal will also be poor (degraded) and the tracing will be help identify dysrhythmia arising from the inferior wall. Most unreadable (noisy). dysrhythmias can be ascertained using one or two leads. It is There are many reasons why an electrode will not func- important for the Paramedic to choose the lead that provides tion. If the gel on the electrode has dried, it will no longer the best chance of identifying the dysrhythmia. serve as an electrical pathway. Electrodes should be inspected For Lead II, one electrode is placed on the right wrist, regularly to ensure new and moist electrodes. one electrode on the left wrist, and one electrode on the left foot (to recreate Einthoven’s Triangle) (Figure 33-6). In many cases, it is inconvenient to place the electrodes out onto the limbs where the wires may become tangled. Therefore, the Paramedic may choose to place electrodes on the right and Street Smart Many Paramedics use the same electrodes for the monitoring ECG as for a 12-lead ECG. Key to an accurate 12-lead ECG is the re-creation of Einthoven’s Triangle. Jowett and associates suggested that placing the limb leads on the torso can lead to inaccurate interpretation of the 12-lead by producing false patterns of ischemia.9 Figure 33-4 Examples of ECG electrodes. The Monitoring ECG 739 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. devices such as pacemakers (automated internal defi brillator/ cardioverters), or medication patches. To ensure patient comfort, connect or clip the wires to the electrodes before attaching the electrodes to the skin. Pressing the snap connection to an electrode that is already on the skin is uncomfortable for the patient. Perhaps more importantly, it squeezes the gel out from under the electrode, potentially causing loss of signal. R.A. L.A. Standard Lead II Confi guration If the negative lead is on the right shoulder and the positive lead is on the left leg, then the ECG machine is monitoring Lead II. Lead II provides a view of the inferior wall of the heart.10–12 The upper portion of the conduction system resides within the inferior wall, from the SA node to the AV node. This portion of the left ventricle also receives its blood supply from the right coronary artery. R.L. Whenever there is suspicion of an acute occlusion of the L.L. (Ground right coronary artery, and therefore doubt about performance electrode) of the upper portion of the conduction system (a conduction abnormality as manifest by changes in the PR interval), then Figure 33-6 Electrode placement for limb leads. the patient should be observed in Lead II. Because Lead II provides an excellent view of the inferior wall/upper portion of the conduction system, it produces the clearest P waves. left upper arms at the deltoids. Lower electrodes are then placed on the right and left thighs. The third alternative Modifi ed Chest Lead I strategy, suggested by Takuma and associates, is to place While it may be easier to distinguish P waves in Lead II, the the electrodes in the subclavicular space (the deltopectoral placement of the electrodes may be more diffi cult in the fi eld. fossae) on the right and left and then on the right and left Also, the electrodes in Lead II may interfere with impor- lower rib cage.8 The important concept is to try to maintain tant procedures such as defi brillation. For these and other Einthoven’s Triangle. reasons, many Paramedics choose modifi ed chest Lead 1 Best results are obtained from placing the electrode over (MCL1) to monitor patients instead of/in addition to Lead II muscle and not over bony prominences. The Paramedic should (Figure 33-7). MCL1 simulates the precordial lead V1, one of also avoid placing an electrode over any jewelry, implanted the six precordial leads of a 12-lead. MCL1 lead Figure 33-7 Lead placement for MCL1. 740 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. By placing the positive monitoring electrode at the right Finally, the best ECG signal is obtained when the area sternal border at the fourth intercostal space, between the is gently abraded to remove dead skin cells and to improve fourth and fi fth ribs, and looking across the chest from the circulation (i.e., increase warmth) to the area. The use of fi ne left shoulder, the Paramedic obtains a view of the anterior grit sandpaper (commercially available for this purpose) or wall of the left ventricle. even a gauze pad to abrade the skin can markedly improve the The MCL1 lead not only permits differentiation of quality of the ECG signal. ectopic complexes (ventricular from supraventricular with aberrancy), but MCL1 keeps the defi brillation platform open for defi brillation pads or paddles. MCL1 also helps the Systematic Approach to ECG Paramedic distinguish between right and left bundle branch Rhythm Interpretation blocks. A new onset left bundle branch block as a sign of an acute coronary event will be discussed later. A rapid and accurate interpretation of a patient’s ECG rhythm Perhaps the most pressing reason to use MCL1 as a mon- is important and potentially life-saving. To attain speed and itoring lead is that it views the anterior wall. The left coro- accuracy, the Paramedic must take a disciplined approach nary artery (LCA), including the left anterior descending to ECG interpretation. Faithful adherence to a systematic coronary artery (LAD), are commonly occluded during an approach analysis of the ECG rhythm strip, a process called acute coronary event and these arteries provide blood to the ECG interpretation, promises the best results in the shortest anterior wall of the left ventricle. MCL1 provides a vantage amount of time. point from which to monitor the anterior wall and quickly There are a number of ECG interpretation schemas avail- identify lethal threatening dysrhythmias such as ventricular able. Some take a simple left to right approach to reading fi brillation. an ECG, similar to reading a book. The method originally described by Dr. Henry J. L. Marriott works well in the out- of-hospital environment as it focuses on rapid identifi cation Preparation of Skin of high-risk patients.14 Dr. Marriott’s systematic approach to Electrodes are designed to adhere to and transmit electrical ECG interpretation also can be easily integrated with the algo- signals from a warm, dry, fl at skin surface. In order to obtain rithmic approach to advanced cardiac life support advanced these conditions, the Paramedic must take several steps to by the American Heart Association. Regardless of the method prepare the skin before applying the electrode.13 of ECG interpretation chosen, the Paramedic should master First, the skin should be relatively free of hair. The that technique and resolve to use that systematic approach Paramedic can clip some hair to ensure electrode contact. with each ECG tracing. Some Paramedics use single-blade razors to clear unwanted chest hair. However, if the patient receives anticoagulants Descriptive Analysis later, then microlacerations created by the razor may bleed. Some Paramedics have a tendency to quickly label an Some Paramedics prefer to use disposable hair clippers spe- ECG rhythm because it looks like another ECG rhythm cifi cally designed for this purpose. However, handheld ban- the Paramedic has seen before. This practice relies on pat- dage scissors, the type with the blunted tips, are adequate to tern recognition. The use of pattern recognition is poor trim chest hair. practice. Errors in ECG interpretation can be made when Next, skin oils must be removed. Skin oils reduce the Paramedics fail to note the fi ne nuances that differentiate adhesion of the electrode and hinder penetration of elec- one rhythm from another (e.g., the difference between a bra- trode gel. An alcohol-soaked pad applied to the area and then dycardia with U waves versus a sinus bradycardia with a pressed against the skin in an outward-circling motion will heart block). remove dirt, oil, and other particulates which could prevent A descriptive analysis provides the building blocks to proper adhesion of the electrode. Visible perspiration also an ECG interpretation. Using the Marriott method of analy- can prevent proper adhesion of the electrode. The alcohol sis, the elements of the descriptive analysis would consist pad also helps to evaporate perspiration. The skin in the tar- of the rhythm, rate, width of the QRS complex, and atrial get area should then be dried with gauze or a towel prior to activity. placement of the electrodes in order to remove debris and Armed with a descriptive analysis, the Paramedic assem- remaining alcohol. bles the information and, using an understanding of cardiac If the patient is grossly diaphoretic, it may be helpful to anatomy (specifi cally electrophysiology), generates a rhythm apply tincture of benzoin. Tincture of benzoin is a topical interpretation. lotion that, when dried, is tacky to touch and helps electrodes On occasion, an ECG rhythm strip baffl es a Paramedic. adhere to the skin. It is important to not apply tincture of The practice of using descriptive analysis allows the benzoin directly over the electrode site as it does not con- Paramedic to accurately describe the ECG rhythm strip to duct electricity well. Properly applied, the tincture of benzoin a physician or another colleague who, in turn, may be able should leave a bull’s eye-appearing ring in which the middle to interpret the rhythm even without benefi t of seeing the is clear of the benzoin. rhythm strip. The Monitoring ECG 741 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Artifact Street Smart In some cases, it may be diffi cult to distinguish the isoelectric line because of artifact. Artifact, a disturbance in the

isoelec- An ECG interpretation should not be made by tric line, is the result of outside interference with the signal. solely observing the ECG monitor. Before an ECG Some artifact may resemble ventricular fi brillation, possibly causing inexperienced EMS providers to react inappropri- interpretation is made, the Paramedic should print ately. More commonly, artifact makes rhythm interpretation out a hard copy of the rhythm displayed on the ECG diffi cult (if not impossible). Therefore, it is important to fi nd monitor and, using descriptive analysis, come to the source of the artifact and try to resolve it. Artifact can result from many causes including patient a conclusion about the rhythm, documenting that movement, problems with the cable, electromagnetic inter- interpretation. ference, or vehicle motion. A systematic problem-solving approach, starting at the patient and moving to the machine, often uncovers the cause of the artifact. Emergency Decision Making Patient-Induced Artifact Some medical emergencies are time-sensitive. Unfortunately, There are many easily understood reasons why the patient there may not be time to come to a comprehensive interpre- may be the source of the artifact. For example, if a patient tation about an ECG rhythm before defi nitive action must be experiences a seizure while on the cardiac monitor the ECG taken. This fact is best evidenced by the advanced cardiac strip will show artifact. In some cases, one of the fi rst warn- life support algorithms. Many of these algorithms intend ings that a Paramedic has that the patient is seizing is the that the Paramedic establish a gross analysis of the ECG sudden appearance of artifact on the monitor and the accom- rhythm strip (e.g., “wide complex tachycardia”) in order to panying rate alarms. Seizures can occur for many reasons use the algorithm. This permits quick action to resolve the (e.g., hypoxia, hypoglycemia, and the sudden hypotension dysrhythmia. A descriptive analysis, as suggested by the that results from ventricular fi brillation). Marriott method, lends itself to this type of swift decision Cardiac compressions performed during resuscitation making. can also create artifact, as can placing an electrode directly over the top of an internal electronic pacemaker. One of the most common reasons for patient-related artifact is poor Street Smart preparation of the patient’s skin prior to printing the ECG rhythm strip. Loose electrodes—undermined by sweat, dirt, An ECG monitor is a valuable tool but is limited by or hair—or dried electrode conductive gel can interfere with the Paramedic’s ability to tie the interpretation of the the signal and cause artifact. Patient movement can also cause artifact (Figure 33-8). rhythm strip to the clinical picture. The assessment of The patient should be made to be as comfortable as possible, an ECG rhythm strip provides only one piece of data in preferably lying supine or semi-reclined and with arms to the the clinical picture. Only when a Paramedic takes this side or on a fl at surface. If artifact is still observed, check for data, adds it to the history, and uses the information subtle movements such as nervous fi nger tapping or grasping the side rails. Try to discourage the patient from raising her obtained from the physical performed on the patient, head in an attempt to observe the ECG monitor. Any muscle can a diagnosis be made. tension can cause artifact. Shivering can also cause artifact. After placing the elec- trodes, the patient should be covered to prevent hypothermia and any subsequent shivering. Finally, fi ne tremulous body Determining the Isoelectric Line movements may be observed on the ECG monitor as arti- fact when the Paramedic administers defasciculating doses The first step in an ECG interpretation is to determine of paralytic drugs. the isoelectric line. The isoelectric line indicates that period of time when the myocardium, particularly the ventricular mass, has been repolarized and awaits depo- Cable-Induced Artifact larization. The isoelectric line extends from the end of ECG cables carry the signal from the body to the ECG the T wave to the start of the ventricular depolarization machine. At the start of every tour of duty, the cables should represented by the QRS complex. An isoelectric line on be visually inspected for cracks in the insulation and loose the monitor and on the rhythm strip should appear as a flat connections to the connectors at both ends. Extraneous move- line between ECG complexes. ment of the ECG harness (cable) can cause artifact. Starting 742 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Figure 33-8 Artifact from patient movement caused the noisy baseline in this ECG tracing. at the patient, the wires should be inspected to ensure that moved away from the environment. For example, perhaps the they are securely fastened to the electrodes. patient can be moved to the rear of the ambulance. Wires that are running over the top of electrodes can cre- ate interference. Therefore, wires should be placed in such a Vehicle Motion Artifact fashion that they run parallel to one another but not on top of Little can be done to prevent vehicle motion artifact cre- one another. The Paramedic should also permit some slack in ated by rough roads. Paramedics will frequently obtain a the cable running from the patient to the ECG monitor. This “clean” (artifact-free) tracing before and after transport for slack removes the tension from the electrode wires and helps analysis and interpretation or while stopped at traffi c control prevent the electrode from being pulled off the patient. devices. Electromagnetic Interference Identify the QRS Complex The fl ow of electricity through an electric device can natu- The next step in the ECG interpretation is to identify the rally generate an electromagnetic fi eld. In most cases, elec- QRS complex. The QRS complex shows the greatest degree tronic devices are shielded to prevent this type of “radiation of variation in duration (length), polarity (direction), and leak.” If, for example, the shielding failed, then an electro- morphology (shape). The QRS complex, representing ven- magnetic fi eld might be created. ECG machines, designed to tricular depolarization, is usually the largest wave visible. detect changes in electricity, would logically be expected to The QRS complex can take on a number of combinations of pick up these fi elds and record them. Electromagnetic inter- the waves Q, R, or S. At this juncture it is not important to ference (EMI) of an ECG is seen as artifact. describe the signifi cance of these wave groupings, but rather Common sources of EMI include radios, cellular to simply identify the presence or absence of a QRS complex. telephones, televisions—in fact, any electronic or radio The purpose of identifying the QRS complex fi rst is so that device.15–17 The fi rst step in eliminating EMI is to turn off the rhythm can be described and then the rate can be calcu- electronic devices in the proximity of the patient and see if lated accurately. the artifact resolves. Another common source of EMI is over- head fl uorescent lighting. These lights, common in commer- Absence of a QRS Complex cial establishments and increasingly more common in homes, If there is no artifact and no QRS complexes are discernable, create a steady electrical signal from the 60-cycle alternating then the rhythm will appear fl atline and the heart may be in current (AC). The resulting artifact distorts the ECG tracing, asystole (no ventricular activity is detected on the surface making it diffi cult to read (Figure 33-9). ECG). The Paramedic’s fi rst reaction should be to confi rm If it is diffi cult to identify the exact source of the electri- that the patient is without pulse and has no signs of life. If the cal interference (i.e., the “noise”), then the patient should be patient is indeed unresponsive, apneic, and pulseless, then it Figure 33-9 Artifact from 60-cycle interference. The Monitoring ECG 743 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. may be necessary to confi rm asystole in a minimum of two memorization trick to help in making calculations (Table leads. It is recommended that asystole be confi rmed in more 33-2 and Figure 33-10). than one lead. The most accurate method of calculating the rate of a If there are no QRS complexes in either lead and the regular rhythm is to count the number of small boxes between monitor shows what appears to be artifact, then the Paramedic any two complexes and divide the result into 1,500. This should immediately palpate for a pulse and signs of life. method will give a very accurate result. Most Paramedics use Again, if the patient is lacking a pulse and signs of life, the a calculator when using this method. Paramedic should assume the chaotic rhythm is ventricular If the rhythm is irregular, an acceptable method is to fi brillation and proceed accordingly. It is beyond the scope count the number of QRS complexes in a six-second strip of the present discussion to talk about the treatment of life- and multiply that number by 10 to get a number per minute threatening dysrhythmias. or a rate. Many ECG printouts have “tic” marks, a line or label, every three seconds either the top or the bottom of the ECG paper. These tic marks help the Paramedic to quickly determine a six-second strip. Therefore, between three tic Street Smart marks is six seconds. The number of QRS complexes within that length of strip, times 10, equals the heart rate in beats per minute. The ECG rhythm may not be visible on the surface Since the rhythm is irregular, the choice of rhythm strip ECG of morbidly obese patients. The heart lacks the is only a snapshot in time. The rate only represents the rate at energy to get a strong enough signal to the surface that moment. However, the rate can be altered by the choice to be sensed. However, the patient may be awake of a different six-second rhythm strip. Therefore this method is the most inaccurate method of rate calculation. and alert. This fi nding adds support to the Paramedic axiom, “Treat the patient, not the monitor!” Clinical Signifi cance of Rate Generally speaking, all rates are normal, fast or slow. Heart rates between 50 and 100 are considered to be normal or nor- mocardiac and further clinical correlation is needed to ascer- Determine Rhythm tain the patient’s condition. The regularity of the rhythm is assessed by measuring from a The fast heart rate, greater than 100 beats per minute, is point on the QRS complex to the same point on the next QRS called a tachycardia and may have clinical signifi cance to complex. Typically, the tallest or deepest wave is used—the the patient’s condition as well. If the patient is exercising, it is R wave in Lead II or the S wave in MCL1. By then visually expected that the heart rate will be tachycardia. However, if inspecting the next waves in sequence and moving from left the patient is lying in bed it would not be anticipated that the to right across the horizontal axis, the Paramedic can deter- patient’s heart rate would be tachycardia. mine if events are occurring regularly, irregularly but with a There are many causes of tachycardia including con- pattern, or irregularly irregular. sumption of caffeine, cocaine, or other intoxicants that mimic Calipers make this task easy. However, care must be adrenaline (sympathomimetics). Other causes include fever, taken not to open or close the calipers inadvertently while moving from R to R. Many Paramedics use a fl at edge or piece of paper to mark the

interval between two R to R points Table 33-2 Large Box Method of Rate and then assess subsequent R points. Some minor irregular- Calculation ity is expected in a normal rhythm. In very slow rhythms, If there is one large box between two QRS complexes, then the an alteration of one to two small boxes, representing 0.04 ventricular rate is 300. to 0.08 seconds difference, is normal and is still considered regular. Continuing the sequence: 2 large boxes  ventricular rate of 150 Calculate Heart Rate 3 large boxes  ventricular rate of 100 Armed with information about rhythm regularity, the 4 large boxes  ventricular rate of 75 Paramedic can choose the best method for determining the 5 large boxes  ventricular rate of 60 heart rate from among the several methods available. 6 large boxes  ventricular rate of 50 If the rhythm is regular, then the quickest method to 7 large boxes  ventricular rate of 43 calculate the rate is to count the number of large boxes 8 large boxes  ventricular rate of 37 between any two QRS complexes and divide the result into 9 large boxes  ventricular rate of 33 300. This method gives an accurate result. An understand- 10 large boxes  ventricular rate of 30 ing of this method will allow the Paramedic to substitute a 744 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Figure 33-10 Rate based on the number of large boxes between two QRS complexes. shock, acute coronary events, and endocrine disorders such QRS Width as hyperthyroidism. After having determined the rhythm and rate, the Paramedic In some cases, the patient may experience a sensation should examine the QRS more closely. The pressing concern of his or her heart racing, a phenomena called palpitations. is whether the QRS is wide, suggesting a ventricular origin, The presence of palpitations should alert the Paramedic to the or it is narrow, suggesting either a sinus or supraventricular possibility of tachycardia. Typically heart rates of less than origin. Ventricular rhythms are usually, but not always, dan- 150 beats per minute are well tolerated by the patient and the gerous because the origin of the rhythm is in the last pace- patient may not feel a palpitation. maker in the ventricles. While a supraventricular rhythm, A slow heart rate, called a bradycardia, may also be a complex originating above the ventricles, can be danger- clinically signifi cant but is usually not life threatening unless ous, it is generally better tolerated by the patient.18 A sinus the rate falls below 50. In that case, the patient may be light- rhythm is a supraventricular rhythm and is considered the headed secondary to hypotension. best situation. In monitoring Lead II, the QRS is normally positive. It generally consists of a small initial Q wave (negative wave Street Smart measuring less than 2 mm) followed by the positive R wave. Normal duration is from 0.04 to 0.12 second in the adult. For monitoring Lead MCL1, the complex normally begins with a It is important to note that the presence of a QRS small, narrow R wave followed by an S wave. The QRS dura- complex does not always equate with the presence tion is the same. If the QRS in any lead is greater than 0.12, of a pulse. A patient can have an electrical rhythm then it is considered to be wide and therefore possibly of a ventricular origin. without a pulse, a condition called pulseless electrical activity (PEA). This phenomenon reinforces the Ectopy Paramedic axiom of “Treat the patient, not the It is essential to determine if every complex is wide or if only monitor.” an occasional complex is wide. If there is an occasionally wide QRS, then this suggests a competing lower pacemaker The Monitoring ECG 745 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. 300 150 100 75 60 50 42 Street Smart Street Smart At this point in the ECG interpretation, there Some Paramedics have a tendency to refer to a is suffi cient information in many cases to start rhythm by its ectopy. This is analogous to referring treatment of the patient. The Paramedic has to a friend by a nickname. However, it is more determined if the underlying rhythm is regular, as descriptive to refer to the rhythm by fi rst describing well as the rate and the width of the QRS complex. the underlying primary rhythm and then the ectopy Advanced cardiac life support algorithms include wide (e.g., sinus rhythm with a bigeminy of wide premature complex tachycardia, narrow complex tachycardia complexes). (both regular and irregular), and symptomatic bradycardia. is abnormal for the P to be notched or peaked. The upper limit of normal for the duration of the P wave (which refl ects atrial depolarization) is 0.12 seconds. site, called an ectopic focus. Any complex that occurs out- The normal height of the P wave is less than 3 mm, or side of the sinus is considered an ectopic complex. three small boxes, rounded and upright in Lead II. This is due An ectopic focus can compete with the sinus node for to the size and arrangement of the atrial fi bers. Any P wave dominance (the fastest cell) in terms of automaticity (creates larger than 3 mm suggests that the atrium may be enlarged the depolarization). If the ectopic focus is ventricular, and the due to an increased workload. Causes of increased atrial work ventricular pacemaker becomes dominant, the patient may include tricuspid valve disease, pulmonary hypertension, cor experience a rhythm called ventricular tachycardia. With pulmonale, or congenital heart disease. ventricular tachycardia, the rhythm is regular, the rate is fast, and every complex is wide. If only the occasional complex is wide (i.e., possibly of Street Smart ventricular origin), then the Paramedic should concentrate on determining the underlying primary rhythm. In many cases, the ectopic comple Lead II is the best single lead to view atrial activity as xes are a result of hypoxia, rate- related myocardial ischemia, or a basic electrolyte disturbance. a rule. The P wave should be upright and rounded in Correction of the ectopic rhythm is best accomplished by Lead II.19,20 correction of the underlying abnormality. In many cases, the ectopic complex appears earlier than would be expected in the course of a regular cardiac cycle. AV Relationships Increased automaticity of the ectopic focus leads to prema- Normally, the sinoatrial node (SA node) discharges, setting ture discharge, and therefore dominance, during depolariza- off a cascade of depolarizations down the conductive pathway tion. Therefore, these ectopic complexes could be described in the heart. When this occurs, the surface ECG will register a as wide premature complexes. P wave followed by a momentary pause, as the signal reaches When an ectopic complex occurs at every other complex, the atrioventricular node (AV node) and then ventricular it is called bigeminy. Bigeminy should not be confused with depolarization occurs, as represented by the QRS complex. the situation in which two ectopic complexes occur together. In a normal sinus rhythm, there should be a P wave imme- These ectopic complexes are called couplets. Ectopic com- diately preceding the QRS. If a P wave is absent, then the pace- plexes can also occur every third beat (trigeminy) or every maker may be down further in the conduction system, either at fourth complex (quadrageminy). Like bigeminy, ectopic the level of the AV node or at the level of the ventricles. complexes that occur three or four at a time are considered to If there are more P waves than there are QRS complexes, be a salvo or a run of ventricular tachycardia. then the complex is being blocked at some point along the conductive pathway. An interruption of AV conduction (an P Waves AV block) can be indicative of disease or ischemia at the Following determination of rhythm, rate, and QRS width, the level of the AV node. While AV blocks can be troubling, the next step is to identify the P wave. The normal morphology resultant bradycardia is of greater concern. and polarity of the P wave is upright (positive) and rounded in monitoring Lead II. It may be upright, fl at, or negative in Intervals monitoring MCL1. After having established rhythm, rate, QRS width, and AV While the P can be biphasic, beginning as a positive relationships, the Paramedic should proceed to examine inter- defl ection then becoming a negative wave or vice versa, it vals. Intervals are periods of time when a certain event—in 746 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. this case, a depolarization of the heart—is expected to occur. Determination of the QT interval in the fi eld is generally Prolonged or shortened intervals can be indicative of under- not necessary, except under certain specifi c circumstances lying abnormalities. (Table 33-3). It is only necessary to ascertain if the QT inter- val is abnormally long. A quick rule of thumb is that the QT PR Interval should be less than one half of the RR interval. The time for conduction down the intra-atrial pathways is rapid. In order to allow time for the blood (a viscous fl uid) Normal Sinus Rhythm to match the speed of electrical conduction, the impulse is Normal sinus rhythm (Table 33-4 and Figure 33-11) is held in the AV node. The AV delay is between 0.12 and 0.20 considered an optimal rhythm. The regular rhythm and rate seconds and is measured from the beginning of the P wave to provide for adequate fi lling of the ventricles and suffi cient the start of the QRS complex, the PR interval. ejection of blood for perfusion. If the PR interval is greater than 0.20 seconds, then the In a regular and normocardiac rhythm, where the P wave impulse is delayed. There are many causes (including isch- precedes the QRS in a timely fashion and the QRS is nar- emia) of a delayed PR interval. In some cases, the PR interval row, the Paramedic may reasonably interpret the rhythm as becomes progressively longer until the AV node no longer normal sinus rhythm. The Paramedic should learn the essen- conducts the electrical impulse. This is another indication of tial parameters of the sinus rhythm, because all other rhythms disease. that are not sinus (i.e., that do not fi t into the essential param- Conversely, if the PR interval (PRI) is shorter than 0.12 eters) are considered to be dysrhythmias. seconds, then the likelihood is that an ectopic pacemaker in the atrium has assumed dominance or that a congenital Sinus Tachycardia abnormal pathway, called an accessory pathway, has become engaged in the conduction of the impulse.21 Sinus tachycardia (Table 33-5 and Figure 33-12), is a sinus rhythm with a rate greater than 100 bpm. All other If there is no relationship between P waves and the QRS measurements of the rhythm remain the same as those for complex (AV dissociation), there may be a complete heart a sinus rhythm. If the heart rate is greater than 150 bpm, block. When a complete heart block occurs, pacemakers lower and the rhythm is sustained, then it is less likely that the

in the heart at the level of the bundle of His, bundle branches, rhythm is a sinus tachycardia but another supraventricular or even the ventricular myocardium will take over as the pace- tachycardia. maker. These secondary pacemakers serve as a fail-safe for the heart but are generally not reliable for the long term. Sinus Bradycardia QT Interval A sinus rhythm becomes a sinus bradycardia (Table 33-6 and Figure 33-13) when the rate falls below 60 bpm, Ventricular depolarization and repolarization is represented though most patients are not symptomatic until the heart on the surface ECG tracing as the QT interval. The QT starts rate falls below 50 bpm. Any rate below 60 is considered at the fi rst defl ection of the QRS complex, regardless of the an absolute bradycardia. Alternatively, some patients can initial wave, and stops at the end of the T wave. be symptomatic with a rate above 60, even though the rate While short QT intervals do exist, some patients have does not meet the criteria for absolute bradycardia. In those congenital short QT syndromes. Paramedics are generally cases, the patient is said to be experiencing a relative bra- concerned with QT widening. QT intervals are affected by dycardia, or a rate that is too slow for the patient’s meta- sex and age. For example, men, on average, have shorter QT bolic needs. intervals (0.39 second) than women (0.41 second) at a heart rate of 70 bpm. However, prolonged QT intervals may repre- sent underlying abnormal electrolyte levels, drugs, and even Table 33-3 Etiology of Prolonged QT Interval— myocardial ischemia. Partial List QT intervals are also affected by heart rate. When 1. Antidysrhythmic drugs assessing a QT interval, the value obtained is corrected a. Vaughn-Williams Class I by using a formula. For example, Bazett’s formula for 2. Tricyclic antidepressants corrected QT interval equals the QT interval divided by the square root of the RR interval. To accommodate the 3. Phenothiazines variables such as rate, QT intervals are reported as cor- 4. Electrolyte imbalance rected (QTc). Any QTc longer than 0.40 / 0.06 seconds a. Hypokalemia in a normal heart rate should be considered prolonged. b. Hypomagnesemia A patient with a prolonged QT segment is at risk for unstable 5. Stroke ventricular tachycardia, specifi cally torsades de pointes.22,23 6. Seizures It should be noted that the QTc is of little clinical relevance 7. Cardiomyopathy in heart rates over 100 bpm. The Monitoring ECG 747 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Table 33-4 Parameters for Normal Sinus Table 33-5 Parameters for Sinus Tachycardia Rhythm (NSR) Rhythm Regular Sinus rhythm originates in the sinus node, the heart’s primary Rate Ventricular pacemaker. Conduction takes place along the conduction pathway, in a time frame conducive to adequate cardiac output. Greater than 100 bpm Rhythm Regular QRS confi guration Same complex to complex Rate Ventricular Upright in Lead II 60 to 100 bpm QRS duration Less than 0.12 seconds QRS confi guration Same complex to complex P wave Rounded and upright Lead II Upright in Lead II Atrial rate Same as ventricular QRS duration Less than 0.12 seconds AV conduction P wave to QRS = 1:1 P wave Rounded and upright Lead II PR interval 0.12 to 0.20 seconds Atrial rate Same as ventricular QT interval Less than 0.44 seconds AV conduction P wave to QRS  1:1 PR interval 0.12 to 0.20 seconds QT interval Less than 0.44 seconds Sinus Dysrhythmia Street Smart Sinus rhythm naturally slows with exhalation and then accel- Sinus dysrhythmia is a normal variant for most people. erates during inspiration. During expiration, intrathoracic pressure decreases. As a result, more blood can return to the It is extremely common in children and young adults. heart, thereby increasing preload. With an increase of blood in For this reason, some Paramedics never refer to a the heart, stretch receptors in the heart’s atrium in turn signal sinus rhythm as “normal” sinus rhythm as this implies the heart to contract slower. During inhalation, the opposite occurs. Sinus dysrhythmia (Table 33-7 and Figure 33-14) is the rhythm is regular and since many people have a most notable in children. The pacer site remains in the sinus slight variation in rhythm which is completely natural. node and conduction follows the usual pathways. II A MCL1 B Figure 33-11 Normal sinus rhythm. 748 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. II Figure 33-12 Sinus tachycardia. II Figure 33-13 Sinus bradycardia. II Figure 33-14 Sinus dysrhythmia. Table 33-6 Parameters for Sinus Bradycardia Table 33-7 Parameters for Sinus Dysrhythmia Rhythm Regular Rhythm Regularly Irregular Rate Ventricular Rate Ventricular Less than 60 bpm 60 to 100 bpm QRS confi guration Same complex to complex QRS confi guration Same complex to complex QRS duration Less than 0.12 seconds Upright in Lead II Upright in Lead II QRS duration Less than 0.12 seconds P wave Rounded and upright Lead II P wave Rounded and upright Lead II Atrial rate Same as ventricular Atrial rate Same as ventricular AV conduction P wave to QRS = 1:1 AV conduction P wave to QRS  1:1 PR interval 0.12 to 0.20 seconds PR interval 0.12 to 0.20 seconds QT interval Less than 0.44 seconds QT interval Less than 0.44 seconds The Monitoring ECG 749 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Out-of-Hospital ECG work and play activities while the Holter monitoring device records the ECG activity. At the conclusion of the desired Monitoring Equipment monitoring period (usually 48 to 72 hours), the device is During transport within a hospital and during the patient’s returned to the cardiologist who, in turn, downloads the infor- hospital stay, the cardiac patient will have electrodes connect- mation to a console or computer for analysis. ing him directly to the ECG device which is both displaying Even Holter monitoring may miss abnormal ECG activ- and storing the ECG tracings. This type of equipment, which ity that tends to occur very irregularly (as in days or weeks may be anchored above the patient’s bed or may be portable, apart). This patient may possess an event monitor, a device is called hard wire monitoring. Its limitation is that it limits that is a little larger than a credit card. When the patient senses the patient’s ability to move around. the abnormal activity, the monitor is placed on the chest for To allow a patient to begin walking in his hospital room the preset period of time. The patient can then telephone the or out in the hallway, some places use telemetry monitors. cardiologist’s offi ce and transmit the data from the card via These devices are connected to the patient by two or three telephone. wires. They collect the data and send it via radio waves to If the Paramedic needs to provide care to a patient with an antenna. The data is then transmitted by wires to the main a Holter monitor, the monitor poses no problem. While the console. The Paramedic should be aware that the radio waves Holter monitor may have hard wires or electrodes connected transmitted by cellular phones can interfere with both hard- to the patient’s chest, the electrode placement for the Holter wire and telemetry systems.24–26 Care should be taken to turn monitor is different than the placement recommended for off cell phones when transporting the patient within the hos- prehospital monitoring. Therefore, both may be used simul- pital setting. taneously without interference with the other device. Keep in mind that some cardiac treatments, such as defi - At-Home ECG Monitoring brillation and pacing, may require access to the patient’s chest. If the Holter monitor needs to be removed, simply In many cases, the problematic dysrhythmia is sporadic in remove it and the electrodes. Turn off the Holter monitor if nature. It is economically impossible to keep a patient in the the device has an ON/OFF switch. Bring the Holter monitor hospital for continuous monitoring for days or weeks in order to the hospital with the patient or give the device to a person to pick up the dysrhythmia. For this reason, a continuous type designated by the patient. The Paramedic should document of ECG monitor called Holter monitoring was invented. the disposition of the device including the name of the person Holter monitoring allows the patient to go about his routine to whom it was given. 750 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. While seemingly daunting at fi rst appearance, ECG interpretation can be learned provided the Paramedic practices ECG analysis and remembers the fundamental rules of the monitoring ECG. To improve the quality and accuracy of ECG interpretation, the Paramedic should take a disciplined and logical approach to ECG interpretation. While an ECG is important to the overall clinical picture, a stand-alone ECG is of little clinical value. It is important to correlate the patient’s clinical picture with the ECG in order to have a meaningful interpretation. Key Points: • Monitoring equipment varies according to the the signal, and a wire to conduct the signal to the specifi c monitoring need, the location of the machine. patient, and the type of event being assessed. • Wire systems vary. The important point is to place • The Paramedic must make a judgment as to the electrodes and attach the wires in such a way whether preexisting monitoring equipment must be as to mimic Einthoven’s Triangle. removed to permit appropriate patient care. • Measurements of duration, amplitude, and polarity • The speed at which the screen or paper moves is are made of each ECG feature. called sweep speed. A change may allow better examination of key features. • Apply a consistent method of assessment and treatment. First, assess the patient for the • The size of the picture on the screen or paper is presence of pulses. Next, assess the width of the called gain. QRS complex. Determine treatment timeliness. • The Paramedic must follow the agency’s policy for • In determining the name of the rhythm: documenting sweep speed and gain, which is called ■ Know the causes of dysrhythmias calibration. ■ Assess the QRS complex • ■ Assess the P waves ECG paper is standardized to allow Paramedics to ■ Do not mistake blips for P waves or miss the measure the timing of events and the intensity of P wave due to size the events. ■ Determine which P wave is related to which QRS • The horizontal axis equals time. Each light line ■ Pinpoint the primary diagnosis equals a time of 0.04 seconds; each heavy line • Normal sinus rhythm (NSR) is considered the equals a time of 0.2 seconds. optimal rhythm for most people. All other rhythms • The vertical axis equals amplitude. Each light line are compared to NSR. equals 0.1 mm or 0.1 mV.

Each dark line equals • The presence of NSR does not eliminate the 0.5 mm or 0.5 mV. presence of patient problems. • To obtain an ECG, there must be an electrical signal, an electrode to reduce skin resistance to ThTeh eM Monointiotroirnign gE CEGCG 751 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Review Questions: 1. What steps should be taken before placing the 6. What can be done to resolve artifact? electrodes? 7. Why is it important to determine rhythm 2. What are the two standard ECG monitoring before rate? leads? 8. What are the three methods of determining 3. How does one place the ECG electrodes for heart rate? these monitoring leads? 9. What are normal and abnormal heart rates? 4. What are some causes of low-amplitude ECG? 10. What are the normal parameters of the QRS? 5. What are some common causes of artifact? Case Study Questions: Please refer to the Case Study at the beginning of the chapter and answer the question below: 1. Explain why analyzing and naming the rhythm could impact the treatment provided to Ms. Sheehan. References: 1. Ferguson JD, Brady WJ, Perron AD, Kielar ND, Benner JP, 8. Takuma K, Hori S, Sasaki J, Shinozawa Y, Yoshikawa T, Currance SB, et al. The prehospital 12-lead electrocardiogram: Handa S, et al. An alternative limb lead system for impact on management of the out-of-hospital acute coronary electrocardiographs in emergency patients. Am J Emerg syndrome patient. Am J Emerg Med. 2003;21(2):136–142. Med. 1995;13(5):514–517. 2. Hurst JW. Naming of the waves in the ECG, with a brief account 9. Jowett NI, Turner AM, Cole A, Jones PA. Modifi ed electrode of their genesis. Circulation. 1998;98(18):1937–1942. placement must be recorded when performing 12-lead 3. Wellens HJ. Bishop lecture. The electrocardiogram 80 years after electrocardiograms. Postgrad Med J. 2005;81(952):122–125. Einthoven. J Am Coll Cardiol. 1986;7(3):484–491. 10. Bayram E, Atalay C. Identifi cation of the culprit artery 4. Campbell PT, Patterson J, Cromer D, Wall K, Adams GL, involved in inferior wall acute myocardial infarction using Albano A, et al. Prehospital triage of acute myocardial electrocardiographic criteria. J Int Med Res. 2004;33(1):39–44. infarction: wireless transmission of electrocardiograms to the 11. McManus JG, Convertino VA, Cooke WH, Ludwig DA, on-call cardiologist via a handheld computer. J Electrocardiol. Holcomb JB. R-wave amplitude in Lead II of an 2005;38(4):300–309. electrocardiograph correlates with central hypovolemia in human 5. Chen EH, Hollander JE. When do patients need admission to a beings. Acad Emerg Med. 2006;13(10):1003–1010. telemetry bed? J Emerg Med. 2007;33(1):53–60. 12. Kataoka H, Kanzaki K, Mikuriya Y. Massive ST-segment 6. Mischke K, Zarse M, Perkuhn M, Knackstedt C, Markus K, elevation in precordial and inferior leads in right ventricular Koos R, et al. Telephonic transmission of 12-lead myocardial infarction. J Electrocardiol. 1988;21(2):115–120. electrocardiograms during acute myocardial infarction. J Telemed 13. Learning D. EKG Tech Video. Utica, New York: Delmar Telecare. 2005;11(4):185–190. Thomson Learning; 1998. 7. Faes TJ, van der Meij HA, de Munck JC, Heethaar RM. The 14. Upshaw CB, Jr., Silverman ME, Henry JL. Marriott: Lucid electric resistivity of human tissues (100 Hz-10 MHz): a meta- teacher of electrocardiography. Clin Cardiol. 2007; analysis of review studies. Physiol Meas. 1999;20(4):R1–10. 30(4):207–208. 752 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. 15. Schlimp CJ, Breiteneder M, Seifert J, Lederer W. Interference of patients with mitral stenosis: the value of the P-wave area. Acta 16.7-Hz electromagnetic fi elds on measured electrocardiogram. Cardiol. 2003;58(2):139–141. Bioelectromagnetics. 2007;28(5):402–405. 21. MacKenzie R. Short PR interval. J Insur Med. 2005;37(2): 16. Kolb C, Zrenner B, Schmitt C. Incidence of electromagnetic 145–152. interference in implantable cardioverter defi brillators. Pacing 22. Shantsila E, Watson T, Lip GY. Drug-induced QT-interval Clin Electrophysiol. 2001;24(4 Pt 1):465–468. prolongation and proarrhythmic risk in the treatment of atrial 17. Fleischhackl R, Singer F, Nitsche W, Gamperl G, Roessler B, arrhythmias. Europace. 2007;9(4):37–44. Arrich J, et al. Infl uence of electromagnetic fi elds on function 23. Roden DM. Clinical practice. Long-QT syndrome. N Engl J of automated external defi brillators. Acad Emerg Med. Med. 2008;358(2):169–176. 2006;13(1):1–6. 24. Brodlie M, Robertson D, Wyllie J. Interference of 18. Mulroy JF, Thayer JJ, King JE. How do I manage stable narrow- electrocardiographic recordings by a mobile telephone. Cardiol complex SVT? Nursing. 2005;35(10):14. Young. 2007;17(3):338–339. 19. Gorenek B, Birdane A, Kudaiberdieva G, Goktekin O, 25. Tri JL, Severson RP, Firl AR, Hayes DL, Abenstein JP. Cellular Cavusoglu Y, Unalir A, et al. P wave amplitude and duration may telephone interference with medical equipment. Mayo Clin Proc. predict immediate recurrence of atrial fi brillation after internal 2005;80(10):1286–1290. cardioversion. Ann Noninvasive Electrocardiol. 2003;8(3): 26. Tri JL, Hayes DL, Smith TT, Severson RP. Cellular phone 215–218. interference with external cardiopulmonary monitoring devices. 20. Zeng C, Wei T, Zhao R, Wang C, Chen L, Wang L. Mayo Clin Proc. 2001;76(1):11–15. Electrocardiographic diagnosis of left atrial enlargement in ThTeh eM Monointiotroirnign gE CEGCG 753 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. KEY CONCEPTS: Upon completion of this chapter, it is expected that the reader will understand these following concepts: • Paramedic use of 12-lead ECG as the fi rst step in a critical care pathway for patients with acute coronary syndrome • Accurate acquisition of the 12-lead ECG • Analysis of the 12-lead ECG to make a patient prognosis, determine treatment, and plan for an appropriate destination Case Study: The Paramedics were called to the home of Jennie Swinter. Mrs. Swinter is an 82-year-old widow, living alone on a small farm that she still farms for vegetables. She called EMS because she became exhausted and out of breath after walking to the bathroom. The inexperienced Paramedic commented that at her age, Mrs. Swinter should be tired and out of breath. The more experienced Paramedic suggested that many acute processes could account for Mrs. Swinter’s complaints. The Paramedics obtained an ECG right after placing Mrs. Swinter on oxygen. It showed ST elevation and hyperacute T waves in Leads II, III, and aVF. Mrs. Swinter complained of feeling very lightheaded and afraid. Repeat vital signs were obtained. Rather than the 118/66 found earlier, she had a pressure of 80/48. She also had jugular venous distention while semi-sitting and clear lung sounds. 754 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Diagnostic ECG—The 12-Lead 755 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. OVERVIEW Death from acute myocardial infarction remains a leading reason for mortality in the United States despite advances in medicine. It has been estimated that 50% of patients with acute coronary syndrome (which, if left untreated, leads to AMI) are transported by EMS and the majority of cardiac arrests occur in the prehospital setting. It is therefore important that Paramedics be able to identify and aggressively treat these patients. Chief Concern ascertain the ventricular wall involved, and predict the coronary artery that is affected. Not only is this information valuable There are a number of causes of chest pain. Of particular con- downstream, to the emergency physicians and cardiologists cern for the Paramedic is chest pain of a cardiac etiology. who will eventually treat the patient, but it is important for the Patients with cardiac-related chest pain are at high risk for Paramedic. By being able to estimate the location and extent acute myocardial infarction and sudden cardiac death. of injury, the Paramedic can predict, with relative confi dence, The identifi cation of the patient with potential for acute the clinical course that the patient will take. This prognostic myocardial infarction is predicated on a clinical history which ability permits the Paramedic to prepare for predictable com- is suggestive of acute coronary syndrome and electrocardio- plications related to the acute coronary event. graphic fi ndings. The latter, electrocardiographic fi ndings, are not always present in patients who are at the beginning of the event (i.e., early in the evolution of the acute myocar- Atypical Presentations of ACS dial infarction). The maxim “Treat the patient, not the moni- While it is obvious that patients with substernal chest pain tor” holds true for these patients. Treatment for suspected (SSCP) should have a 12-lead ECG, other occasions when a acute myocardial infarction—specifi cally morphine, oxygen, 12-lead ECG may be necessary are sometimes less obvious. nitrates, and aspirin—should not be withheld because of a For example, middle-aged females often do not present with lack of electrocardiographic fi ndings. It has been estimated chest pain. These patients tend to present with atypical pre- that upward of 50% of patients who will develop an acute sentations for acute coronary syndrome.5,6 myocardial infarction had no confi rmatory electrocardio- These atypical presentations can include sharp rather graphic (ECG) fi ndings upon the initial ECG.1–4 than crushing chest pain, shortness of breath, unexplained weakness, and sudden diaphoresis. Unfortunately, some of these symptoms can be mistaken for menopausal signs, lead- Street Smart ing to delayed treatment. The belief that a patient with an acute coronary event must have concomitant substernal chest pain is a misconception. One study suggested that serial 12-lead ECGs Another group of patients who have an atypical presen- identifi ed acute myocardial infarctions in 75% of tation are the elderly. This group of patients tends to have a patients upon whom the initial 12-lead ECG exhibited higher frequency of acute myocardial infarction, even when nonspecifi c ECG changes. The importance of an identifi ed early in the evolution, and complications such as heart and renal failure. early baseline 12-lead ECG was supported by that For these reasons the Paramedic should have a low study. Therefore, it is advisable for all Paramedics threshold for 12-lead ECG acquisitions. The best support for to obtain an initial baseline 12-lead ECG as soon as this argument is found in the frequency that 12-lead ECG is obtained in the emergency department. possible. Thereafter, serial 12-lead ECGs should be performed every 15 to 30 minutes for the fi rst 2 hours of patient contact. Rhythm Strip The primary mission of all Paramedics has always been to prevent sudden cardiac death from dysrhythmia. This has However, that is not to dismiss the importance of obtain- been the essence of Paramedic care since the advent of ing a 12-lead ECG as soon as possible on a patient with sus- Dr. Pantridge’s “mobile coronary care units” in Belfast, pected acute coronary syndrome. A 12-lead ECG can also help Ireland, over half a century ago. However, with the advent the Paramedic estimate the location of the coronary occlusion, of fi brinolytics and invasive cardiology, the original mission

756 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. has been expanded to include rapid acquisition and interpre- heart. They observed a triphasic pattern to the electricity’s tation of 12-lead ECGs. fl ow. The 12-lead ECG stands at the center of the decision Continuing the work of Bayliss and Starling, Willem pathway when managing patients with ischemic chest pain. Einthoven, who had also witnessed Waller demonstrate an Delays in obtaining the 12-lead ECG must be eliminated ECG in 1889, used a silver string galvanometer to reproduce whenever possible. The most effective means of obtain- the triphasic waves that Bayliss and Starling had observed. ing a 12-lead ECG at the earliest point in time is to have a Willem Einthoven named the defl ections of these waves P, Q, Paramedic obtain one.7 R, S, and T, a convention that lasts to this day. The importance of obtaining a rapid and accurate 12-lead Continuing his work with the “electrokardiogram” ECG is underscored by the American Heart Association’s (EKG) in 1905, Einthoven transmitted his fi rst EKG over (AHA) statements. The AHA states that upon recognition 1.5 kilometers to another lab using a telephone cable. This was of acute coronary syndrome and a suspected acute coronary the fi rst recorded experience with telemetry.10 Einthoven also event, a 12-lead ECG should be obtained as soon as pos- went on to standardize the electrocardiogram by referencing sible but no later than ten (10) minutes upon arrival at the the body and using the designators Leads I, II, and III. These hospital.8,9 This rapid 12-lead ECG acquisition and interpre- fi rst leads formed an equilateral triangle which is now referred tation will facilitate the patient’s transfer to cardiac centers to as “Einthoven’s Triangle.” From this platform, Einthoven for interventional cardiology. This time frame has been dem- was able to distinguish normal “EKG” from abnormal, noting onstrated to decrease both morbidity and mortality. premature ventricular contractions, heart blocks, atrial fl utter, The effi ciency of this process can be substantially and other dysrhythmia. For this and other work, Einthoven was improved with 12-lead ECGs being obtained by Paramedics awarded the Nobel Prize in medicine in 1924 for “inventing the and the diversion of ambulances to cardiac centers. The electrocardiogram.” He is commonly referred to as the “father American College of Emergency Physicians (ACEP) supports of electrocardiology.” this process in their position paper entitled “Out-of-Hospital 12-Lead ECG.” Standard Limb Leads While ACEP acknowledges that 12-lead ECG acquisition Einthoven’s limb leads used two electrodes, one negative and will prolong scene times, many Paramedics have become very one positive, and measured the electrical potential between adept at obtaining 12-lead ECGs in minimal time. Studies these electrodes as it fl owed from negative to positive. Because have shown that Paramedics can obtain 1 2-lead ECGs at the the limb leads required two leads which measured the current point of care in the fi eld in approximately 5 minutes. difference between the leads’ electrodes, they were—and still The advent of Paramedic 12-lead ECGs has greatly are—referred to as bipolar leads. Einthoven’s original bipo- affected physicians’ opinions of Paramedics regarding the lar limb leads provided electrical information relating to the treatmet of acute coronary syndromes. Paramedics are viewed heart’s electrical activity along the frontal plane of the body as a part of the continuum of care that starts in the fi eld and (Figure 34-1). ends in the interventional cardiologist suite. It is recognized Perhaps the most useful of these bipolar leads was Lead II that aggressive Paramedic care can substantially impact car- in that its orientation, from right shoulder to the left foot, was diac patient morbidity and mortality. more or less in alignment with the heart’s electrical conduc- tion system. For this reason, Lead II provides the best view of Origins of the Electrocardiogram error of conduction. It is often used to monitor patients for an The electrocardiogram has a long history that may have started irregular heart rhythm, a disturbance in conduction along the with Italian physicist Carlo Matteucci. Matteucci, interested heart’s electrical pathway, called a dysrhythmia. in the works of the noted physicist Luigi Galvani, continued Unfortunately, because of its orientation along the frontal Galvani’s work on bioelectricity and started to investigate the plane, Lead II only permits a view of the heart’s inferior wall. role of electricity in the human body. Matteucci observed that However, the bulk of the ventricular mass is in the anterior wall.11 with every heartbeat there was a passage of electrical current in the body. What Matteucci did not realize when he made Even with the use of three limb leads, the ECG only that observation was that he was actually witnessing the birth viewed the frontal plane and the inferior and lateral wall of of electrocardiography. the heart (Figure 34-2). However, the majority of the ventric- Following Matteucci’s early lead, noted British physi- ular mass lies along the transverse plane in the anterior wall. ologist Augustus Waller, of St. Mary’s Medical School in Thus, even with these additional leads, the electrical activity London, created the fi rst tracing of the heart’s electrical of the anterior wall was still not being captured by the ECG. activity using his lab assistant Thomas Goswell as a patient in 1887. Subsequently, British physiologists William Bayliss Precordial Leads and Edward Starling from the University College of London, In an effort to obtain a more comprehensive view of the heart, following Waller’s direction, attached a terminal to the right researchers sought to create new leads. In 1931, researchers hand of a patient and to the skin overlying the apex of the Wilson, MacLeod, and Barker devised a method for recording Diagonostic ECG—The 12-Lead 757 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. R L RA LA – I + – – R L CT F II III F + + i RL LL Figure 34-1 Standard limb leads. Figure 34-3 Wilson’s central terminal (i.e., the virtual negative electrode) and the creation of the unipolar lead. aVL electrode is now available to become an “exploring” lead aVR which can be placed anywhere on the thorax to view any angle of the heart. The use of a single positive electrode, using Wilson’s central terminal, created the unipolar lead Lateral (Figure 34-3). I Using the central terminal concept, Wilson placed elec- CX RCA LAD trodes in a semicircle around the precordium, that portion of skin that overlies the heart. Wilson’s unipolar precordial chest leads encircled the anterior ventricular wall from the septal wall on the right to the lateral wall on the left. This permitted a complete view of the anterior myocardium. These leads were originally called the V leads (V for voltage). In 1938, the American Heart Association Inferior standardized the precordial leads and called them V1, V2, V3, V4, V5, and V6. Adding these precordial (chest) leads III aVF II to the standard limb leads gave nine views of the heart along both the frontal plane and the transverse plane. Figure 34-2 Frontal plane’s relationship to the heart. Augmented Leads— A More Complete Picture the electrical activity of the heart along any of its surfaces. While six precordial chest leads gave physicians a better view They continued to use the three limb leads. However, through of the anterior wall, the three bipolar limb leads did not give the use of electrical resistors, they were able to move the neg- physicians the same view of the inferior wall. Einthoven’s ative electrode to the center of the body, proximal to the right Triangle (the origin of the standard limb leads) is an equilat- atria and the SA node, to form a central point called Wilson’s eral triangle and has, by defi nition, angles of 60 degrees. Use central terminal (CT). of these angles left wide gaps with the potential for much of Because the negative electrode is a “virtual” electrode, the heart’s electrical activity to be unrecorded by these stan- not an actual electrode, in the center of the body, the positive dard limb leads. 758 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. r o Ante i r RA LA + RA LA RA LA LL + Lead a VR + LL LL Lead a VF Lead a VL Figure 34-4 Augmented lead placement and the relationship of augmented limb leads to the standard limb leads. Using Wilson’s central terminal theory, Goldberger simple ECG rhythm monitor, a narrower frequency range recorded the activity between each of the limb leads’ posi- between 0.5 Hz and 30 to 50 Hz removes distortions which tive electrodes and the central terminal, adding three addi- interfere with the rhythm’s correct analysis. However, it does tional limb leads. Unfortunately, when the signals were so at the cost of accuracy when measuring segments of the recorded, they were too small to be properly examined and ECG complex. In the simple ECG rhythm monitor, an ST seg- required a boosting of the signal in order to identify any ment may appear far above (elevated) or below (depressed) the characteristics. In 1942, Goldberger devised a method to baseline, indicating potential ischemia or acute injury/infarct. boost, or augment, the signal (hence the title “augmented” Paramedics are generally directed to take patients with an ST leads) (Figure 34-4). segment above baseline to an interventional cardiology cen- Combining the lead type and the positive electrode loca- ter as opposed to the local hospital.12–15 A false positive in this tion gave rise to the names of Goldberger’s augmented leads regard is not only an inconvenience to the patient and to the (i.e., augmented voltage right or aVR, then augmented voltage patient’s family, but misuses critical cardiac services needed left or aVL, and augmented voltage foot now called aVF). for more acutely ill patients. To obtain a proper diagnostic 12-lead ECG that correctly Acquisition of the 12-Lead ECG shows all segments, the American Heart Association recom- mends that a frequency range of 0.05 Hz to 150 Hz be used. The importance of acquiring a high-quality 12-lead ECG, However, switching from monitoring mode to diagnostic as explained earlier, cannot be overstated. Clinical decisions mode raises the problems of artifact which were previously regarding the patient’s treatment and transportation are based, eradicated. Therefore, the Paramedic must take other mea- in part, on the 12-lead ECG. Therefore, it is imperative that sures to reduce artifact. the Paramedic know how to obtain a clear and concise 12-lead ECG. 12-Lead ECG Artifact Diagnostic 12-Lead ECG The common sources of ECG artifact can be broadly classi- fi ed as physiologic and nonphysiologic. Physiologic artifact versus Rhythm Monitoring includes muscle artifact and skin artifact. The fi rst, muscle Tracings of early ECGs were often plagued with artifact and artifact, is the result of muscle movement or muscle tension. distortions that made reading the ECG diffi cult. These early Muscle tension is the result of agonist and antagonist muscles ECG machines were intended to monitor the rhythm only. To competing to maintain a limb in one position. Any time a solve these problems, electrical engineers resorted to adjust- muscle contracts, it produces an electrical current which will ing the frequency range, that area of the electric signal that be detected

as an electromyographic signal (EMG) by the is being recorded. They also used electronic fi lters such as ECG. An EMG is seen as narrow rapid spikes on the ECG common mode rejection. monitor.16 In order to capture subtle changes in amplitude and dura- To prevent EMG on the ECG, the patient should be posi- tion which are necessary for the interpretation of a diagnostic tioned comfortably, in an effortless position, with arms and 12-lead, the 12-lead ECG monitors require a wider frequency legs supported by the stretcher. In some cases, it may be more range than simple three-lead ECG rhythm monitors. In the prudent for the Paramedic to perform the ECG on the patient’s Diagonostic ECG—The 12-Lead 759 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. bed or couch rather than the stretcher because the patient’s Patient Preparation arms hang off the stretcher. Folding of the arms across the chest only creates muscle tension and resultant EMG. To prevent EMG interference, the Paramedic should fi rst The other source of physiologic artifact is skin move- place the patient in a comfortable position. Preferably, the ment. Whenever the skin is stretched under an electrode, it patient should be supine with arms at the sides and the entire will create an epidermal signal. For example, when a patient body supported. If the patient is not relaxed, because of a inhales and exhales, the movement of the skin will create painful condition such as arthritis, then the Paramedic might baseline shifts (wandering baseline) as the electrodes move consider using analgesia or sedatives. along with the chest wall. To prevent epidermal signal inter- The Paramedic should then prepare the skin before apply- ference, it is important to properly place the electrodes on the ing the electrodes. If the patient’s chest hair interferes with the patient’s chest away from the thoracic cage. Paramedic’s attempts to closely adhere the electrodes to the An example of a nonphysiologic source of ECG artifact skin, then the chest hair needs to be removed. While it might is electromagnetic interference (EMI). Whenever alternat- be expeditious to use a straight razor to remove the hair, shav- ing current (AC) electricity passes through a wire, it produces ing the chest can create microlacerations that can bleed if the an electromagnetic fi eld. Therefore, whenever a 12-lead ECG patient is given fi brinolytics later. Also, the hair follicles can monitor is in the vicinity of a wire carrying AC electricity, become infected (folliculitis). The patient’s chest hair should the monitor will pick up the electromagnetic fi eld as 60-cycle be carefully trimmed using either a commercially available interference. An example of common sources of 60-cycle clipper or a pair of blunt tipped bandage scissors. EMI are fl orescent lights, particularly those with a malfunc- tioning ballast, and poorly shielded ambulance convertors. Visually, 60-cycle EMI will present on the 12-lead ECG as a Street Smart fuzzy baseline. Static electricity can also produce artifact on the ECG. The patient may build up an electrical charge (static electric- If the patient is grossly diaphoretic, some Paramedics ity). When the patient, as the charged body, is in proximity of have used antiperspirants to dry the area. These an uncharged body, such as the ECG monitor, then electricity antiperspirants often contain aluminum oxide as an will pass between the two and be recorded on the ECG. This active agent. Aluminum oxide interferes with the occurs frequently in dry climates. One of the more common sources of artifact is electrode electrical signal and will reduce the quality of the failure. Since the outer layer of skin is electrically “dead,” an 12-lead ECG. electrical signal cannot be transmitted across the skin with- out a conductive medium to act as a bridge between the inner body and the electrode. The typical ECG electrode uses sil- While wiping the contact surface with a gauze pad will ver chloride as the conductive medium. When a metal, such reduce the pickup of 60 Hz EMI and motion artifact, it will as silver chloride, is placed next to an electrolyte solution only reduce the skin’s resistance by 1,000 to 5,000 ohms. (i.e., the interstitial fl uid), then an electromagnetic force is It is important to not only remove the dead cells of the created and an electromagnetic “signal” is sent to the ECG stratum corneum but to also scratch the lower stratum monitor. granulosum.17 Scratching the stratum granulosum improves the ECG signal by allowing the electrode gel to permeate the skin and contact the electrolyte solution (i.e., interstitial fl uid). Street Smart Typically, either fi ne weight sandpaper (220 to 3,400 grit) or a commercially available gritty ECG preparation gel is used. Most 12-lead ECG cables are covered, or shielded, Five to ten strokes of either a gel-soaked gauze pad or sand- to prevent the monitor from picking up extraneous paper is suffi cient. The skin should be slightly reddened but not abraded. 60-cycle EMI. The presence of 60-cycle EMI on the The area immediately surrounding the electrode contact monitor is a sign of either a defective cable or a should be cleansed with an alcohol-soaked preparation pad. broken lead. The alcohol helps to remove surface fats which can under- mine the electrode’s adhesive and prevent close skin contact with the electrode’s gel. If the skin is not properly prepared, then the skin can cre- It is important that the gel on the electrode be moist. Most ate an impedance to this signal of approximately 100,000 to electrodes come prepackaged and have an expiration date. 200,000 ohms. Simple site preparation can reduce the skin’s The Paramedic should fi rst confi rm that the electrodes are impedance to less than 10,000 ohms in 90% of patients and not expired before proceeding. Next, the Paramedic should thereby markedly improve the quality of the ECG signal. remove the electrode from the package and remove the plastic 760 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. The electrode should be placed on the properly prepared skin Street Smart overlying muscle, not bone. The resulting leads—Lead I, Lead II, and Lead III—are therefore a function of the polarity ascribed to them by the ECG monitor. Often these electrode Electrode gels depend on the body’s warmth to wires are labeled for ease of application. liquefy the gel so that it can penetrate the skin. If the While technically correct, the placement of electrodes patient’s skin is cold, then the gel will not melt and on the ankles and wrists of the patient is often mechanically the ECG signal will be poor. Waiting until the patient inconvenient. Problems with resting tremors and clothing pre- vent the Paramedic from obtaining an accurate 12-lead ECG. is warmed, or applying hot packs over the electrodes, This distortion can be minimized if the electrodes are moved can improve the quality of the ECG. more centrally. In 1966, Mason and Likar suggested mov- ing the electrodes to the shoulders and the hip. To properly place the limb electrodes in the Mason–Likar modifi cation, protective cover over the gel. With one fi nger, the Paramedic the right arm electrode is moved to the right infraclavicular should gently compress the gel. Moist electrode gel should fossa, approximately 2 cm below the clavicle. The left arm have a little spring when gently compressed. Dried electrode electrode is similarly placed in the left infraclavicular fossa, gel will be stiff and unyielding. Dried electrodes should be and the left leg electrode is moved next to the left iliac crest in discarded immediately as they are of no practical use. the iliac fossa. This placement of the limb leads maintains the After confi rming that the gel on the electrode is still moist, integrity of Einthoven’s Triangle without the inconvenience the lead wire should be attached to the electrode. The gel under of distal limb lead electrodes. the electrode is formed into a pod so that the gel stays concen- Because the ECG machine electrically converts the bipo- trated in an area when the electrode is then placed on the skin. lar limb leads into unipolar augmented leads using the same If the electrode is placed on the skin fi rst and then the lead wire leads and electrodes, it is unnecessary to add additional elec- is attached, the pressure from attaching the lead wire can crush trodes for the augmented leads. the pod, disperse the gel, and diminish the signal quality. Street Smart Street Smart To ensure consistency in application of the 12-lead If moisture or blood is expected to cover the electrode, ECG data, the Paramedic should document if the the application of bio-occlusive dressing over the 12-lead ECG was obtained using the Mason–Likar electrode can prevent the moisture from undermining modifi cation. The documentation may simply state the electrode and interrupting the ECG signal. that all electrodes were placed on the torso. Electrode Placement Precordial Leads Wilson’s precordial leads measure the ECG potentials across Accurate electrode placement is important. In some cases, the anterior wall of the left ventricle. Precordial leads are to the prehospital 12-lead ECG may not display ischemic be placed according to specifi c landmarks. Variation in the changes. However, when serial ECGs obtained later are com- placement of precordial electrodes can sometimes produce pared against the initial 12-lead ECG, the differences become diagnostically signifi cant changes in the 12-lead ECG. apparent. These comparisons are only valid if the electrodes The fi rst electrodes, V1 and V2, are placed within the 4th have been placed in the same position. intercostal space at the right and left sternal border, respec- The American Heart Association emphasized proper lead tively. Mistakenly, Paramedics may palpate the space just placement in 1938 when it fi rst standardized the placement below the clavicle, assume it is the 1st intercostal space, and of precordial leads. It continues to establish the standard for start counting down three more spaces. This placement is electrode placement in order to obtain a clinically relevant incorrect and will cause V1 and V2 to be placed too high. 12-lead ECG.18 The Paramedic should fi rst identify the suprasternal notch above the sternum and palpate inferiorly until a ridge is felt. Standard Limb Leads The ridge on the bone is the connection of the manubrium Limb leads are traditionally placed where Einthoven placed to the body of the sternum (the angle of Louis). Moving lat- them—on the end of the extremities. One electrode should be erally to the right, the Paramedic should palpate the second placed on the ventral surface of the right and the left wrist and intercostal space along the sternal border and then palpate the another placed on the ankle proximal to the medial malleolus. spaces downward until the 4th intercostal space is palpated. Diagonostic ECG—The 12-Lead 761 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Figure 34-5 Precordial electrode placement. The fi rst precordial electrode, V1, is placed on the right The Paramedic should document if it is necessary to per- s ternal border and V2 is placed across from V1 at the same form the 12-lead ECG on a patient in a semirecumbent posi- level on the left sternal border. tion, such as in a wheelchair

or recliner. The patient’s change From the V2 position, the Paramedic should palpate the in position from Fowler’s position, at a 45-degree angle, causes 5th intercostal space and move laterally to the midclavicular the heart to swing anterior and closer to the chest wall. line to place the V4, the third electrode. The fourth electrode placed is V3, which is placed midpoint along an imaginary Dextrocardia line that runs between V2 and V4. Continuing to palpate along the 5th intercostal space, the Some patients have a congenital condition in which the body’s Paramedic should place V5 at the left anterior axillary line, organs are mirror opposite of normal. Situs inversus, which in line with the iliac crest, and V6 at the 5th intercostal space is a complete reversal of all thoracoabdominal organs, occurs along the left midaxillary line (Figure 34-5 and Table 34-1). in less than 1 in 10,000 patients but has been a documented If the patient has large breasts, male or female, place V4 medical phenomenon since 1643. If the heart and lungs are under the breast and V3 over the breast. The V4 electrode opposite and the abdominal organs are in their usual position, should be placed fl at against the chest and not partially on the this is referred to as dextrocardia.19 breast and the chest. This position would cause the electrode When the Paramedic initially places the patient on the to fold over on itself and will not sense the electrical activ- monitor to determine a rhythm, it will be noted that Lead I ity. If the patient is small or thin, then place the electrodes is inverted. An inversion in Lead I is suggestive of dextrocar- between the ribs, avoiding the bony prominences, if possible. dia. A standard 12-lead ECG will support the diagnosis. The patient with dextrocardia will have a P wave axis greater than Table 34-1 Lead Names with Correct Electrode 90 degrees and a poor R wave progression, both discussed Placement shortly.20 If dextrocardia is suspected, or the patient confi rms LA Left arm over muscle or fl esh dextrocardia, then the Paramedic should proceed by placing RA Right arm over muscle or fl esh the electrodes on the right side of the thorax. The Paramedic LL Left leg over muscle or fl esh should make a note on the 12-lead ECG printout that dextro- RL Right leg over muscle or fl esh cardia is suspected and right-sided chest leads were placed. V1 4th ICS RSB, 4th right intercostal space at the sternal border V2 4th ICS LSB, 4th left intercostal space at the sternal border 12-Lead ECG Tracing V3 Between V2 and V4 V4 5th ICS MCL, 5th left intercostal space at the midclavicular line Before reading a 12-lead ECG the Paramedic must under- stand the standard layout of the printout. Like a rhythm, a V5 5th ICS LAAL, 5th left intercostal space at the anterior axillary line 12-lead ECG is never read off the monitor screen but instead V6 5th ICS LMAL, 5th left intercostal space at the midaxillary line is printed out for careful analysis. 762 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Figure 34-6 Normal 12-lead ECG. A 12-lead ECG is printed in a standard four-column For ease of conceptualization, the left ventricle is said format. The 12-lead ECG machine reads three leads simul- to have four walls. It is actually a cone-like shape with taneously for 2.5 to 3 seconds until all 12 leads are obtained artifi cially contrived sides. The lower portion of the left ven- and then prints out the 12-lead ECG. tricle, next to the epigastrium, is called the inferior wall. The Beginning on the far left column, the printout contains the portion of the left ventricle that is shared with the right ventri- standard limb leads I, II, and III. The 12-lead ECG machine then cle (the septum) is called the septal wall. That foremost por- uses the limb leads and, with the creation of Wilson’s central tion of the left ventricle, where the bulk of the myocardium terminal, creates the augmented leads, aVR, aVL, and aVF. exists, is called the anterior wall. The last wall, the lateral wall, Moving from the limb leads to the precordial leads, the is actually an extension of the left ventricle’s anterior wall. 12-lead ECG machine reads and records the precordial leads, starting with V1, V2, and V3, then reads and records V4, V5, Contiguous Leads and V6 (Figure 34-6). In some instances, the 12-lead ECG machine will simul- An ECG lead gives the Paramedic a view of a particular taneously record both the 12-lead ECG and the monitor lead portion of the left ventricle. The 12-lead ECG allows the and a single monitoring strip may be printed across the bottom. Paramedic to have several views of the heart in an effort to Although most machines will default to Lead II for the moni- try and capture evidence of myocardial injury. When two or toring strip, the Paramedic may choose to record a different more leads look at the same wall of the left ventricle, they are lead depending upon the patient’s condition. said to be contiguous leads. ECG leads are related to each other by the position of the positive electrode which, in turn, affords a specifi c view of Street Smart a particular portion of the ventricle. In the standard 12-lead ECG, the limb leads II, III, and the augmented lead, aVF, the positive electrode is located on the lower extremity and looks Some older 12-lead ECG machines can only print a up toward the bottom of the heart. The bottom of the heart is single lead at a time. These machines, called single- a portion of the left ventricle called the inferior wall. Thus, channel machines, print the 12-lead ECG in the same these leads (II and aVG) are called inferior leads and can be said to be contiguous. sequence but in one very long ECG strip. Leads I, aVL, V5, and V6 have the positive electrode located on or beneath the left arm. These leads look at the heart’s lateral wall and are called lateral leads. Similarly, Electrocardiographic Assessment leads V1 through V4 have the positive electrode on the front of Left Ventricular Function of the chest. These leads look at the front portion or anterior wall of the left ventricle. The front of the chest is a large The left ventricle is essential for cardiac output to the body area. Thus, these leads are broken into subcategories. V1 (in general) and to the brain (in particular). All other portions and V2 have the positive electrode over the interventricular of the heart (the atriums and the right ventricle) could be con- septum and are also referred to as septal leads. V3 and V4 sidered auxiliary to the left ventricle. In fact, loss of any one continue to be known as true anterior leads. of these auxiliary portions of the heart is survivable, whereas In some cases, the evidence of myocardial damage loss of the left ventricle is usually fatal. For this reason, the spreads across two walls of the left ventricle. In those cases, 12-lead ECG focuses on the left ventricle. both walls are used in the description. For example, injury Diagonostic ECG—The 12-Lead 763 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Table 34-2 Contiguous Leads artery. The right coronary artery (RCA) runs the length of the heart and has a minor branch, called the marginal branch, • Pure changes towards its terminus. Conversely, the left coronary artery  II, III, aVF  Inferior (LCA) divides almost immediately at its mainstem into the  V1, V2  Septal left anterior descending coronary artery (LAD) and the cir-  V3, V4, V5  Anterior cumfl ex (Cx).  I, aVL, V5, V6  Lateral The right coronary artery (RCA) provides blood to the infe- • Mixed changes rior wall of the left ventricle and to the AV node in the majority of patients. Thus, ECG changes in the inferior leads of II, III,  V1, V2, V3, V4  Anteroseptal and/or aVF would suggest that the RCA may be involved.  I, II, III, aVL, aVF, V5, V6  Inferolateral The left main coronary artery serves the entire anterior  I, aVL, V3, V4, V5, V6  Anterolateral wall including the septum. Occlusions of the left main stem,  II, III, aVF, V1, V2  Inferoseptal referred to as “widow makers” (thus emphasizing the impor- • Global changes tance of the LCA), can cause global anterior wall damage.  V1, V2, V3, V4, V5, V6  Global anterior ECG changes in the anterior leads of V1 to V4 and the lateral  I, II, III, aVL, aVF, aVR, leads of I, aVL, V5, and V6 suggest that the LCA is affected.  V1, V2, V3, V4, V5, V6  Global The LCA almost immediately bifurcates, giving rise to the left anterior descending (LAD) coronary artery and the cir- cumfl ex coronary artery (Cx). The LAD artery serves the cen- to both the anterior wall and the septal wall, as evidenced tral portion of the anterior wall of the left ventricle. Therefore, by ECG changes in the contiguous leads V1, V2, V3, and anterior wall ECG changes would be expected (V3 and V4). V4, would be referred to as anteroseptal. Similarly, myo- Lesser branches off the LAD, called the septal perfora- cardial damage to both the inferior and the lateral wall, as tors (SP), provide the septum with blood, including the bundle evidenced by ECG changes in Leads I, II, III, aVL, aVF, V5, branches. Atherosclerotic involvement of the SP will injure and V6 would be called inferolateral. If there are changes the septum and may cause ECG changes in leads V1 and V2 suggestive of damage to the entire myocardium (i.e., ECG and possible bundle branch blocks. changes in all leads), then the term “global” is used. ECG The LAD then continues to run along the anterior inter- changes in only two contiguous leads are necessary to make ventricular (AIV) groove which separates the right and left a presumption of myocardial injury (Table 34-2). ventricles toward the apex of the heart. Along its path another minor branch of the LAD, which cuts diagonally away from the AIV and toward the anterolateral wall and the apex of the Street Smart heart, is the diagonal (Dx). Distal occlusions of the Dx can give rise to ECG changes in leads I, aVL, V5, and V6 as well as V4 and V5. When a Paramedic sees global changes across all The circumfl ex coronary artery (Cx) was the second artery of the 12-leads, consideration should fi rst be given at the bifurcation of the left coronary artery. The Cx follows the to extra-cardiac causes (i.e., those conditions, atrioventricular groove to the lateral wall of the left ventricle. In most cases (approximately 85% of patients), the Cx stops at such as hypoxia, that could lead to damage to the the left lateral wall. In 15% of patients, the Cx continues and entire heart).21–23 The likelihood that all of the provides perfusion to the AV node. Normally blood for the AV coronary arteries could have a catastrophic event node comes from the right coronary artery. In those cases, the patient is said to be “left dominant,” indicating an alternative simultaneously is extremely unlikely. blood supply to the AV node as opposed to the normal blood supply. The diffi culty for the patient who is left dominant arises when an

occlusion of the left coronary artery occurs and almost Relationship to Coronary Arteries the total of the left ventricle’s myocardium is hypoperfused The main coronary arteries perfuse specifi c areas of the heart (Figure 34-7 and Table 34-3). and, in particular, the left ventricle. By evaluating the 12-lead ECG for evidence of myocardial injury in the contiguous leads, the Paramedic can infer that ECG changes in those Interpretation contiguous leads raises a suspicion of involvement of specifi c The primary value of a Paramedic-obtained 12-lead ECG coronary arteries. in the fi eld is the identifi cation of myocardial injury and The coronary arteries originate at the sinus of Valsalva the patient’s transportation to the defi nitive care center. and proximal to the aortic valve, with which they have a sym- However, the value in a 12-lead ECG is not only in the iden- biotic relationship. There are two coronary arteries which are tifi cation of myocardial injury but also in the Paramedic’s simply called the right coronary artery and the left coronary ability to make a prognosis based on that information. By 764 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Left coronary artery Left circumflex branch Right coronary artery Muscular branch Left anterior decending branch Marginal branch Figure 34-7 Coronary artery anatomy. Table 34-3 Relationship of Leads to Walls to Coronary Arteries • II, III, aVF  Inferior Right coronary artery (RCA) * • V1, V2  Anteroseptal Left anterior descending (LAD)/(SP) * • V3, V4  Anterior Left anterior descending (LAD) • V3, V4, V5, V6  Anterolateral Diagonal (Dx) • I , aVL, V5, V6  Lateral Circumfl ex (Cx) • V1, V2, V3, V4, V5, V6  Global anterior Left mainstem (LCA) R L Septal activation from left to right having information about the location of the myocardial injury, the Paramedic can prepare for complications associ- Figure 34-8 Septal depolarization. ated with that injury. 12-Lead ECG Identifi cation A Q wave is not always visible in every patient, nor is it seen in every lead (Figure 34-8). The presence of a small Q wave, of Myocardial Injury called a physiologic Q wave, is normal.24 Following the depolarization of the septum, ventricular The era of the ECG identifi cation of acute myocardial infarc- depolarization occurs. Normally, ventricular depolarization tion may have started with Harold Pardee when he published proceeds from the endocardium outward to the epicardium the fi rst ECG of an acute myocardial infarction, describing (Figure 34-9). The specifi c wave pattern (i.e., rS, Rs, etc.) is a the T wave as “tall” and “starts from a point well up in the function of the electrode’s placement. For example, since the descent of the R wave.” From that point, physicians have energy is going away from V1, the QRS defl ection should be had a keen interest in using the 12-lead ECG to identify the negative. The energy is going toward V6 and the QRS defl ec- patient with acute coronary syndrome who is at risk for an tion in V6 should be primarily positive. acute myocardial infarction. Normally the segment between the QRS and the T wave, Normal Depolarization called the ST segment, is isoelectric as the Purkinje fi bers start to repolarize (Figure 34-10). and Repolarization Ventricular repolarization is represented by the T wave. Normal ventricular depolarization begins with the onset In a reverse process, normal repolarization begins at the epi- of the QRS complex. The fi rst negative defl ection, called a cardial surface and progresses through the ventricular walls Q wave, represents the depolarization of the septum. to the endocardium. The process of repolarization involves Diagonostic ECG—The 12-Lead 765 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. * * * * * * R L R L R L Activation of anteroseptal region of the Activation of major portion of ventricular Late activation of posterobasal ventricular myocardium myocardium from portion of the left ventricle, endocardial to epicardial surfaces the pulmonary conus, and the uppermost portion of the interventricular septum Figure 34-9 Ventricular depolarization. Ventricular Ventricles Ischemia repolarization repolarized Injury 450 ms 600 ms Infarct Electric force due to infarct + – + – + – – + + – – –– + – + R + + R T T P P Q Q Figure 34-11 The ischemic penumbra. Figure 34-10 Ventricular repolarization. cell necrosis and myocardial infarction called penumbra resuming a negative interior of the cell compared to the out- (Figure 34-11). The cellular changes that occur during pen- side. The combination of the interior of the cell becoming umbra can be witnessed by the Paramedic as changes in the more negative while moving away from the positive electrode ECG. These ischemic patterns are the result of abnormal results in a positive defl ection on the screen. The T wave rep- repolarization. resenting ventricular repolarization is positive or upright in There are three successive stages before myocardial all leads except aVR. cell death: ischemia, injury, and infarction. These stages are evolutionary and affect tissues incrementally, spread- Ischemic Patterns ing out from a central point in a bull’s eye fashion. They can be described as the three “I’s” of acute coronary syn- A healthy myocardial cell requires oxygen, glucose, and a drome (ACS). balance of electrolytes in order to function (i.e., to depolar- ize, then repolarize). Abnormal depolarization/repolarization Ischemia occurs whenever the myocardial cells lack these essential conditions. The most common cause of myocardial dysfunc- The fi rst change is myocardial ischemia. During the isch- tion is acute occlusion of the coronary arteries. emic phase, myocardial cells are deprived of oxygen and As a result of this occlusion, and subsequent hypoxia, hypoxia ensues. During this phase, the myocardial cells the myocardial cells go through a predictable pathway to convert to anaerobic metabolism to conserve energy. This 766 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. J Point V1 V4 To decide if an ST segment is depressed or elevated, the Paramedic starts by identifying the J point. The J point is the start of the ST segment and is found at the juncture of V2 V5 the QRS and the ST segment, the point where the angle from the QRS changes. To fi nd the J point, the Paramedic starts at the beginning of the P wave and draws a straight line across V3 V6 to where it crosses the T wave. If any portion of the ST seg- ment is below that line, then there is ST-segment depression. If any portion of the ST segment is above this line, there is an Figure 34-12 Hyperacute T waves. ST-segment elevation. If the Paramedic is unable to fi nd the beginning of the P wave, then the line is drawn from the bot- tom of the calibration wave straight across. decreased cellular activity slows myocardial repolariza- tion. As coronary perfusion occurs from the surface (or epi- ST-Segment Elevation cardium) inwardly, the deeper myocardial tissues become As the injury continues and becomes full thickness (transmu- ischemic fi rst. This limited ischemic involvement is called ral), the ST segment starts to rise (ST-segment elevation). subendocardial ischemia. This slowing of repolarization Myocardial injury, as manifested by ST-segment elevation does not alter the direction of repolarization; therefore, the in the ECG leads overlying the area, generally occurs after ECG will appear normal, but it does lengthen the time for 20 to 40 minutes of ischemia.25 Some examples of ST- repolarization. Accordingly, the fi rst manifestation of myo- segment elevations in the anterior leads include some cardial ischemia can be a lengthening QT interval. “tombstone” elevations in V2, V3, and V4 (Figure 34-13). As the cell’s sodium–potassium pump starts to falter, due to insuffi cient ATP, potassium leaks from the cell. The Patterns of Ischemia and Penumbra leaking potassium causes an increase in the amplitude of the At this point, the Paramedic may see a complex picture of T waves, called a hyperacute T wave, in the leads facing T wave inversions, ST-segment depressions, as well as ST the damage (Figure 34-12). elevations. These markings represent the process of ischemia Transmural ischemia occurs as the ischemia and are manifestations of penumbra. The key is to focus on reaches the point where it affects the entire thickness of those leads that indicate the greatest degree of damage. The the myocardium, from the endocardium to the epicardium. other ECG changes should radiate away from the location of Then, the deeper myocardial cells begin to malfunction. the primary event. Normally, when repolarization occurs, the polarity changes as potassium is pumped back into the cell. This reverses the cur- Infarction rent. Repolarization results in an upright T wave on the ECG. However, when the ischemic endocardial cells deeper in Without oxygen, the myocardial cells eventually die (myo- the myocardium fail to repolarize, the result is a loss of the cardial infarction), and the area begins necrosis, a physi- change in direction of polarity which normally occurs dur- ologic process in which dead cells are removed and new ing repolarization. This failure to change in direction causes cell growth may occur. The ECG hallmark of this change a negative defl ection in the T wave. Without repolarization is the development of pathologic Q waves. Pathologic and the subsequent negative polarity of the myocardium, the Q waves indicate electrical silence (i.e., no depolarization) normally upright T waves become inverted in the ECG leads that overlay the ischemic area. In some cases, inverted T waves will be one of the fi rst electrocardiographic changes that the Paramedic will observe. Street Smart Injury It is estimated that in some 50% of initial ECGs taken The persistent hypoxia causes the myocardial cells to change on patient’s with cardiac related chest pain, the from ischemia to injury. The faltering sodium–potassium pump of the injured myocardial cells can no longer maintain Paramedic may not see ST-segment elevations with polarization and the cell becomes electrically inert. At fi rst the initial 12-lead ECG because the event has not the injured endocardial cells tend to draw the ST segment evolved to that level. Nevertheless, it is important to downward (ST-segment depression). An ST segment, by defi nition, is a >1 mm depression below the J point from iso- obtain a baseline ECG for later analysis, particularly electric baseline. To decide if the ST segment is depressed, for QT intervals and T wave changes. the Paramedic must fi rst ascertain the J point. Diagonostic ECG—The 12-Lead 767 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. A B C D E F Figure 34-13 ST-segment elevation due to acute MI tracings. A and B show oblique straightening; C and D show a concave upward appearance; E and F show a more horizontal or fl attened ST appearance. in that portion of the ventricular wall. Because that portion Pathologic Q

Wave of the ventricular wall is electrically silent, the depolariza- QRS tion in the opposite wall, going away from the electrodes in complex that lead, is the only signal present. It is recorded as a nega- tive defl ection on the ECG. Width Q waves can also represent the depolarization of of QRS: the intraventricular septum. As the septum depolarizes 1 Box from left to right, any leads that are looking from the left 0.04 sec. (i.e., the lateral leads I, V5, and V6) will show a negative defl ection. These physiologic or septal Q waves are normal x (Figure 34-14). While some Q waves are normal (physiologic), the Q waves associated with infarction (pathologic Q waves) are deep (greater than 25% of the R wave) and wide (typi- cally 0.04 seconds). These characteristics, and the presence Q wave >1/3x of Q waves in contiguous leads, suggests pathology and infarction.26 The presence of a Q wave in a 12-lead ECG is confi rma- tion that the patient has had a transmural myocardial infarc- A significant Q wave should be: 1. One-third height of QRS complex tion. Q waves can remain for years, alerting the Paramedic 2. 0.04 second (one small box wide) in duration to the presence of an acute myocardial infarction (AMI) in the past. In up to 30% of 12-lead ECGs with Q waves, Figure 34-14 Q waves. 768 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Street Smart A Normal An isolated pathologic Q wave in Lead III may be a Ventricular G wall normal fi nding and is not indicative of an inferior wall AMI unless it is accompanied by other ECG changes in the contiguous leads II and aVF. B Ischemic area T Wave S-T the Q waves resolve, especially in the inferior wall, within C Ischemic zone one year.27 "Injury" Electrocardiographic Diagnosis Q of Acute Myocardial Infarction D Ischemic zone Zone of "injury" Infarction To make an electrocardiographic diagnosis of acute myo- cardial infarction, the Paramedic looks for hyperacute T waves, T wave inversions, ST-segment depressions, and ST-segment elevations as well as Q waves in all leads. E Ischemic zone When a pattern of ischemia is noted (ECG changes in con- Infarction tiguous leads), then the Paramedic may have a high index of suspicion that the artery which perfuses the correspond- ing wall is occluded.28 The presence of Q waves in the face of concomitant ST F Infarct (healed) elevation speaks to the evolution of the infarction and may Scar indicate that this MI has been in progress for several hours (Figure 34-15). However, the presence of ST elevations indi- cates that there may be myocardium that can be salvaged with Figure 34-15 Wave changes during evolution thrombolytic therapy or interventional cardiology. of myocardial damage. Reciprocal Changes Supporting evidence of an acute myocardial infarction in Table 34-4 Reciprocal Changes progress are reciprocal changes. Reciprocal changes are ST-segment depressions seen on the 12-lead ECG in leads Reciprocal Reciprocal Wall Artery Lead Wall Leads that face the wall opposite of those with ST-segment eleva- tions. Reciprocal changes are more commonly seen in infe- Inferior RCA II, II, aVF Lateral I, aVL rior wall AMI (approximately 70%) versus anterior wall AMI Anterior LAD V3, V4 Inferior II, III, aVF (about 30%).29,30 The presence of reciprocal changes is an Lateral Cx I, aVL, V5, V6 Inferior II, III, aVF excellent marker of acute myocardial infarction in progress and has a positive predictive value of 90%. The ST-segment depression of reciprocal changes is thought to be due to “mirror refl ections” of the electrical signal from the affected wall. The ST-segment depression seen in a reciprocal change is more downsloping than those Street Smart caused early in an AMI and is typically seen when the AMI is large. ST depressions seen in reciprocal changes can be As an example of the predictive value of reciprocal helpful in distinguishing infarction from the normal changes, ST depression in leads V1, V2, V3, and V4 (all ante- variants in African American males who have ST rior leads) suggests an acute myocardial infarction in evolu- tion in the posterior wall and an occlusion of the circumfl ex elevations. artery (Cx) (Table 34-4). Diagonostic ECG—The 12-Lead 769 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. R Wave Progression may also observe that the T wave is opposite in defl ection to the QRS in all precordial leads, as well as a notching in the In a normal 12-lead ECG, there is a series of changes in the anterolateral leads. primary defl ection of the QRS from negative in V1 to posi- The characteristic appearance of a notched QRS in V6 tive in V6, called an R wave progression, in the precordial (i.e., RsR’) is the result of the electrical impulse crossing the leads. Starting with the deep S wave in V1, the defl ection right bundle branch, depolarizing the right ventricle, then in the precordial leads gradually changes direction, with a crossing the interventricular septum to depolarize the left transition at approximately V3 or V4, until V6, where there ventricle. is a tall R wave. A common cause of an LBBB is occlusion of either the Whenever there is an electrical disturbance in the ante- left anterior descending (LAD) coronary artery or one of the rior wall, secondary to ischemia, then the R wave progression septal perforators which branch from the LAD. These coro- is disturbed (specifi cally when there is a loss of R waves in nary arteries perfuse the septum and the bundle branches that the anterior precordial leads). The loss of an R wave progres- lie within. sion, sometimes called a reverse R wave progression, is sug- Because of the delayed repolarization, the ST segment of gestive of an anterior wall AMI. the septal leads will be elevated and the 12-lead ECG will have If the transition occurs early (i.e., before V3), it may be the appearance of an anterior wall AMI (AWMI). However, indicative of a posterior wall AMI. The Paramedic may then there are a number of benign conditions, including advanced want to consider obtaining leads V7, V8, and V9 (discussed age and hypertension, that can also cause an LBBB.31 later). If the transient occurs later, after V4, it can be sug- In some cases, because of advanced atherosclerotic dis- gestive of an anterior wall AMI. However, a late transition ease, the patient may experience a rate-related bundle branch can also occur if the patient has a thick chest or has respira- block. These blocks occur because the bundle branches are tory disease, particularly if there are small R waves in the incapable of repolarizing, secondary to decreased perfusion, right precordial leads, or may be a normal variant in some at faster rates. Because of slower conduction, there is reduced women. strength of contraction and the patient may experience heart failure. Street Smart Street Smart Some Paramedics may use the term “poor R wave progression.” The American Heart Association prefers Whenever an LBBB occurs, the patient is at risk of the term “reverse R wave progression” instead. It heart failure. Therefore, the administration of any should be noted that improper lead placement can Vaughn-Williams Class 1 drugs (i.e., lidocaine or cause a reverse R wave progression. procainamide) can slow conduction even further, leading to worsened heart failure and even to drug- induced complete heart block. The isolated appearance of a reverse R wave progression (RRWP) should not be taken to mean that the patient is hav- ing an anterior wall AMI. There are other causes of RRWP Typically, the altered electrical pathway associated with which include a pre-existing left bundle branch block, dex- LBBB makes the ECG diagnosis of AMI complicated. Therefore, trocardia, and Wolff–Parkinson–White (WPW) syndrome. if a Paramedic observes an LBBB on initial 12-lead ECG, no Nevertheless, the presence of a reverse R wave progression, further interpretation is possible because a diagnosis of AMI by coupled with a good history for ACS and other 12-lead ECG ECG cannot be made with confi dence. However, the presence of changes in the anterior leads, is helpful in diagnosing an ante- a new onset LBBB during the course of patient care is an ECG rior wall AMI. fi nding highly suggestive of an AMI. The Paramedic should report the appearance of a new New Onset Left Bundle Branch Block onset LBBB and, coupled with a patient history suggestive A left bundle branch block (LBBB) (Figure 34-16) is a par- of ACS, have a high index of suspicion that the patient is tial heart block (when the impulse fails to be conducted) having an AMI.32–34 Patients with a new onset LBBB have which involves one or both the left fascicles of the left bun- a worse prognosis for their AMI compared to those without dle. As a result, the ventricular wall of the affected side must the conduction delay. Because of the prolonged conduction, be depolarized by a wave front from the opposite side. This and the resultant decreased inotropy, a patient with an LBBB delay in depolarization prolongs the QRS to greater than may experience as much as a 25% loss of cardiac output. 0.14 seconds for a left bundle branch and a small narrow Paramedics should treat new onset LBBB more aggressively, R wave (less than 0.04 seconds) in all leads. The Paramedic with a keen eye on the development of heart failure. 770 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. I aVR V1 V4 II aVL V2 V5 Block of left main bundle branch Right or III aVF V3 V6 bundle block of left anterior branch and posterior fascicles Wide QRS complex prolonged (≥ 0.12 second). with ST depressions and inverted T waves, particularly in leads I, aVL, V5 and V6 Electrical vector directed toward left ventricle as is normal, but delayed and prolonged Figure 34-16 Left bundle branch block. infarction (MI) or ischemia, heart failure, pulmonary embo- Street Smart lism, or valvular disease. An LBBB during the course of an AMI can progress Nondiagnostic ECG to a complete heart block. As a result of this In some cases, the patient may have a benign 12-lead ECG. The absence of patterns of ischemia on a 12-lead complete heart block (CHB), the escape rhythm ECG does not preclude the diagnosis of an AMI. When the will be idioventricular. Typically, patients with an 12-lead ECG is nondiagnostic, the Paramedic should main- idioventricular rhythm require a pacemaker. tain a high index of suspicion based on the patient’s clinical presentation and, more specifi cally, the history of present illness. Right Bundle Branch Block In some cases, the diagnosis of AMI on 12-lead ECG is missed because of the low amplitude of the QRS. When the A right bundle branch block (RBBB) is a type of heart block amplitude of the QRS is less than 5 mm in the standard limb in which the impulse fails to be conducted down the right leads (i.e., low amplitude QRS), an assessment of ST-segment bundle of the bundle of His. In a RBBB, the impulse travels change is nearly impossible. Causes of low voltage, resulting rapidly to depolarize the interventricular septum and

down the in a low amplitude QRS, include pericardial effusions leading left bundle branch to activate the left ventricle. Since the right to constructive pericarditis, pleural effusions, and obesity.35–37 bundle branch is blocked, the impulse must cross the inter- ventricular septum to activate the right ventricle. Because it takes more time to depolarize the entire ventricle, the QRS is Electrical Alternans greater than 0.12 seconds in width. When every other ECG complex has alternating amplitude The ECG diagnosis of RBBB is also supported by a (i.e., the one QRS complex is smaller when compared to small terminal R wave in V1 and a slurring of the S wave in the next), then the patient may have electrical alternans. the lateral leads (i.e., Lead I and V6). The T wave in V1 will Electrical alternans is more frequently seen in the precordial also be in the opposite defl ection of the QRS. leads and is a sign of pericardial effusion. A RBBB is one of the most common defects in ventricular The alternating amplitude of the QRS is thought to be the conduction (Figure 34-17). RBBB occurs often, and without result of the heart swinging, in a pendulum fashion, from apparent cause, in normal hearts. Treatment is directed at the the wave created in the pericardium as the heart beats within cause of the conduction defect, which can include myocardial the accumulation of fl uid. Diagonostic ECG—The 12-Lead 771 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. I aVR V1 R' V4 R II aVL V2 V5 Sinoatrial (SA) node Atrioventricular Left anterior fascicle (AV) node Common III aVF V3 V6 bundle of His (AV) Bundle Right and left bundle Block branches Purkinje fibers Total QRS complex prolonged (≥0.12 second). Terminal broad S wave in lead I. RSR' complex in lead V1 Late abnormal Left posterior electrical vector fascicle bypasses block Figure 34-17 Right bundle branch block. Alternative Etiologies for ECG Abnormalities Street Smart The Paramedic should keep an open mind when reading a 12-lead ECG for alternative causes of prolonged QT intervals, One of the fi rst ECG changes associated with T wave abnormalities, and ST-segment elevations. Although hypothermia is a prolonged QT interval. The diffi culty these aberrant changes do not typically mimic the pattern in obtaining a 12-lead ECG, because of the cold skin of ischemia, a quick glance could mislead a Paramedic into thinking that there is a pattern of ischemia. Careful atten- and resultant poor penetration of the electrode gel, tion to the ECG for patterns of ischemia and a disciplined makes this assessment problematic. approach to interpretation will yield the best results. Prolonged QT Intervals The length of the QT interval is inversely related to the One of the fi rst ECG changes which can occur as a result patient’s heart rate. Therefore, when calculating a patient’s QT of anterior wall myocardial ischemia (AWMI) can be a pro- interval, it must be corrected with the heart rate. Typically, longed QT interval. However, there are a host of other etiolo- Paramedics and physicians use Bazett’s formula to obtain gies for prolonged QT intervals.38,39 The majority of causes the correct QT interval. Under emergency conditions, the of acquired prolonged QT intervals involve electrolyte QTc (corrected QT) can be derived from information on the abnormalities (e.g., hypokalemia) and medications. Vaughn- 12-lead ECG. Alternatively, the Paramedic can take the heart Williams Class I and III drugs are the leading offenders and rate and, for every ten (10) beats above 70, subtract 0.02 sec- have been repeatedly implicated as the cause of prolonged onds from 0.40 seconds, and for every ten (10) beats below QT intervals. Other potential offenders include psychotropic 70 add 0.02 seconds. medications (particularly tricyclic antidepressants and phe- nothiazines), antibiotics (such as erythromycin), and toxins T Wave Abnormalities (such as organophosphates).40 Generally, the T wave in a normal ECG is in the same defl ec- In some cases, the cause of the prolonged QT interval is tion as the preceding QRS in the limb leads. The normal congenital. These patients may have presented in their youth T wave is slightly asymmetrical, with the upstroke of the with unexplained syncopal episodes. For this reason, any leading edge of the T wave being gentle compared to the patient, regardless of age, who has an unexplained syncope downstroke. Any deviation from those conditions would should be a candidate for a 12-lead ECG. be abnormal. 772 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. T wave abnormalities can include T wave inversion, fl at- Table 34-6 Causes of ST-Segment Depression tened or low-amplitude T waves, and peaked or hyperacute T • Hypokalemia waves. There are numerous causes for the T wave abnormalities • Hypothermia that can be suggestive of a number of disorders (Table 34-5). With the exception of hyperkalemia, the isolated presence of • Hypertrophy–Ventricular a T wave abnormality is not diagnostic of any condition and requires further investigation. Medications, for example, can cause alterations in the Hyperacute T Waves ST segment. A classic cause of ST-segment depression is digitalis. Digitalis alters ventricular depolarization, resulting Hyperacute T waves are defi ned as T waves greater than 5 mm in a “ladle” appearance of the ST segment (Figure 34-18). in the limb leads and greater than 10 mm in the precordial Other causes of ST-segment depression include suba- leads. While a peaked T wave in contiguous leads is sugges- rachnoid hemorrhage and hypokalemia. Hypokalemia (serum tive of ischemia, hyperacute T waves in all leads is highly sug- potassium less than 2.8) will produce ST-segment depression in gestive of hyperkalemia.41,42 Hyperkalemia can be the result 80% of patients, along with fl attened T waves (Figure 34-19). of renal failure or crush injury, or seen in cases of diabetic Similarly, ST-segment elevation can be a normal vari- ketoacidosis (DKA). Conversely, fl attened T waves are sugges- ant, with some patients demonstrating a 1 to 2 mm ST seg- tive of hypokalemia, a defi cit in serum potassium that can be ment rise, particularly if the ST segment has an upward the result of potassium-wasting diuretics (e.g., furosemide). concavity and/or a notch at the J point (Table 34-7). This fi nding is particularly common among African Americans ST-Segment Abnormalities and leaves the ST segment with a fi shhook appearance. While an ST-segment depression is suggestive of ischemia when seen in select contiguous leads, a global ST-segment depression, affecting all of the precordial leads, suggests the Street Smart etiology is likely extra-cardiac (Table 34-6). Table 34-5 Potential Causes of T Wave Current pacemakers are so effi cient that they do not Abnormalities leave a “foot print” (a pacer spike) on the rhythm • CNS disorders strip. The only evidence of a pacemaker may be the  Cerebrovascular accident (CVA) slow and wide QRS as well as a slight ST-segment  Subarachnoid hemorrhage elevation noted in the precordial leads. • Cardiac disease  Mitral valve prolapse  Myocarditis Special Case of Pericarditis  Pericarditis Pericarditis is an infl ammation of the pericardial sac. As the  Ventricular hypertrophy pericardium surrounds the entire heart and is closely adherent  Conduction disorders to the heart’s surface, infl ammation of the pericardium will • Bundle branch block cause diffuse and widespread ST-segment elevation in practi- • Ventricular preexcitation cally all leads of a 12-lead ECG.43 • Post ventricular tachycardia When the ST-segment elevations appear unrelated to the • Electrolyte disorders pattern of ischemia seen with any specifi c coronary arteries, there should be a suspicion of pericarditis. Further assessment,  Hyperventilation including auscultation for a pericardial rub and an assessment • Pulmonary conditions of the chest pain while lying and seated, are in order.  Pulmonary embolism  Pneumothorax • Gastrointestinal conditions Table 34-7 Etiologies of Normal ST-Segment Elevation  Acute pancreatitis  Acute cholecystitis • Therapeutic digoxin • Pharmacology • Pre-excitation syndromes   Digitalis WPW   Antidysrhythmic agents LGL  Alcohol • Early repolarization syndromes (Congenital)   Cocaine Brugada syndrome Diagonostic ECG—The 12-Lead 773 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Figure 34-18 Digitalis effect on the ST segment. Figure 34-19 Hypokalemia. Nonspecifi c ST Changes In some instances, the ST segment changes do not fi t a pat- Vasospastic Angina tern of ischemia, nor are they contributory toward another One of the causes of transient patterns of myocardial is diagnosis. In some cases, the ST changes are transitory but chemia is vasospasm. This vasospasm may be the result of not evolutionary. In those cases, the Paramedic merely notes many etiologies, including hyperventilation. These patients that the 12-lead ECG has nonspecifi c ST changes. may present with symptoms consistent with acute coro- There are a number of causes of nonspecifi c ST changes nary syndrome. 12-lead ECGs taken during this time will including improper lead contacts, electrolyte abnormalities, d emonstrate ST-segment elevations that seemingly dis- drug-induced changes, and hyperventilation. Even a drink of appear spontaneously. This condition is called variant or cold water can cause nonspecifi c ST changes. Prinzmetal’s angina. 774 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Approach to 12-Lead ECG Diagnostic Quality Interpretation The last information in the left lower corner of the 12-lead ECG is related to frequency response (Figure 34-22). When There are several published approaches to the analysis and the ECG is used as a monitor for dysrhythmia, the machine interpretation of the 12-lead ECG and each of these meth- reduces the frequency response (i.e., the sample from the sig- ods has one common characteristic. Success in accurate nal) to 0.5 Hz and 20 to 50 Hz. This helps eliminate some of 12-lead interpretations requires a disciplined approach to the the artifact but also diminishes the quality of the ECG. analysis as well as the avoidance of any presumptions. Most The 12-lead ECG must have a frequency response of Paramedics read a 12-lead ECG from left to right, starting 0.05 (not 0.5) Hz to 150 Hz. By “opening” the range, minor at the left corner. The left corner provides information about changes in the ECG are observable. In this way, the 12-lead calibration, speed, and diagnostic quality. ECG can be diagnostic. Unfortunately, the artifact and noise eliminated by the narrow sample supports the importance of Calibration proper skin preparation and proper electrode placement. The 12-lead ECG machine is a scientifi c instrument. As such, it needs to be calibrated to ensure its accuracy. Unlike the 12-Lead ECG Analysis past, when Paramedics had to physically calibrate the ECG Having confi rmed that the 12-lead is accurate (calibrated) machine, current machines are self-calibrating. To demon- and that the 12-lead ECG is diagnostic, the Paramedic can strate this internal calibration, the ECG machine marks the then proceed to analysis. There are several systems of analy- calibration as a squared off calibration mark at the beginning sis.

The P, Q, R, S, T method helps to ensure that no change of the recording (Figure 34-20). Standard gain is 1 mV to or abnormality is left undetected. Regardless of the method- 10 mm (10 small boxes) of amplitude. ology of analysis, the Paramedic should always maintain a Speed detailed approach to analysis and never rush to judgment over what appears to be obvious signs of ECG changes. The deci- The paper speed (Figure 34-21) is critical for the analysis of sion to label a 12-lead ECG as indicative of acute coronary the 12-lead ECG. The correct paper speed should be 25 mm/ syndrome must be coupled with the patient’s clinical picture second. In some instances, the Paramedic may have slowed and the whole picture taken into consideration. the paper speed to better analyze slope characteristics. (The The start of every 12-lead ECG analysis is to confi rm delta wave of WPW is sometimes diffi cult to discern when the that the patient is not experiencing a dysrhythmia. The fi rst paper speed is 25 mm/second.) However, a slower, or faster, mission of a Paramedic and emergency physician remains the paper speed will impact on the measurement of intervals (i.e., treatment of dysrhythmia. This point is emphasized by the PRI, QRS, and QT), leading to errors in interpretation. placement of a rhythm strip on the bottom of some 12-lead Calibration mark Figure 34-20 Calibration marking on the 12-lead ECG. Diagonostic ECG—The 12-Lead 775 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Paper speed Figure 34-21 The paper speed is indicated on the 12-lead ECG. Frequency response Figure 34-22 The frequency response is indicated on the 12-lead ECG. ECGs. Once the Paramedic has confi rmed that the patient that are indicative of either an old myocardial infarction or a rhythm is normal (i.e., there is a P wave associated with a new myocardial infarction that is late in its evolution. The lat- QRS) and sinus in origin, then the Paramedic can proceed to ter fi nding, Q waves in a late evolving MI, have some impli- the rest of the analysis. cations for further complications. Some Paramedics analyze the 12-lead ECG by pro- Following a search for Q waves, the Paramedic should ceeding in a left-to-right and top-to-bottom fashion. Other take a moment and look at the R wave progression. A reverse R Paramedics, with a trained eye, look for Q waves in the leads wave progression (RRWP) is suggestive of anterior ischemia. that are associated with specifi c coronary arteries (e.g., Leads A RRWP can be likened to an early warning system, alert- II, III, and aVF) overlying the right coronary artery located ing the Paramedic to the possibility of sudden cardiac death in the inferior wall. Paramedics look for pathologic Q waves before other ECG changes, such as ST-segment elevation, 776 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. occur. Anterior wall MI (AWMI) can rapidly progress to Paramedic Prognosis either heart failure or sudden cardiac death. If the AV node is suffering from a lack of oxygenated blood, it Next, the Paramedic should look for ST-segment eleva- will malfunction. As noted in previous chapters, the AV node tions and ST-segment depressions, which are indicative is responsible for delaying the impulse and allowing the atria of reciprocal changes. The importance of delaying to fi nd to contract and push blood into the ventricles. The node is ST-segment elevations, suggestive of an ST elevation myo- also the electrical connection between the atria and the ventri- cardial infarction (STEMI), is to reinforce the importance cles. The artery that serves the AV node is the right coronary of a disciplined approach and to prevent the Paramedic from artery. If ischemic or injury patterns in the ECG leads which leaping to conclusions. look at the area served by the RCA occur, the Paramedic can Finally, the Paramedic would turn to analysis of the T anticipate conduction abnormalities in the monitoring strip. waves. While T waves are supportive of an argument for ACS, The conduction abnormalities may lead to a decrease in coro- isolated T wave abnormalities may have no signifi cance at all. nary output suffi cient to decrease preload and drop the blood Therefore, T wave changes should only be considered in the pressure. Concurrently, blood may back up into the venous context of other ECG changes and the patient’s history. system, leading to distention in the neck veins. Also associ- ated with RCA occlusions are bradycardias. 12-Lead ECG Interpretation With LAD occlusions, the conduction is affected at the Like the approach to a 12-lead ECG analysis, the approach bundle of His, making for more serious conduction abnor- to the 12-lead ECG interpretation must likewise be dis- malities and unreliable escape mechanisms. The anterior wall ciplined. First, the Paramedic should assemble the list of is the largest portion of the left ventricle and is responsible abnormalities (i.e., presence and location of Q waves, R for ejecting blood into the high pressure system. Damage to wave progression, ST changes, and T wave abnormalities). the anterior wall may lead to the inability to eject the blood Refl ecting on these changes, the Paramedic should assess delivered to it and the backup of blood to the lungs. Anterior for lead groupings. Lead groupings are ECG changes in wall damage caused by occlusion of the LAD may lead to contiguous leads that are suggestive of involvement of a pump failure. Treatment options for anterior wall damage specifi c ventricular wall. include anticipation of cardiogenic shock, gross irritability of Armed with this information, the Paramedic can attempt the muscle cells leading to ventricular fi brillation, and reduc- to identify the culprit artery that is involved. Understanding tion of heart rate and workload, leading to a reduction in myo- coronary artery involvement can help the Paramedic pre- cardial oxygen demand. dict the progression of the acute coronary event and prepare for these predictable events. For example, the right coro- Further 12-Lead ECG Interpretation nary artery (RCA) supplies the AV node in the vast majority As the heart’s muscle depolarizes, the energy moves down the of patients.44 ECG changes suggestive of an inferior wall electrical pathway from the sinoatrial node (SA node) to the myocardial infarction (IWMI) implicate the right coronary atrioventricular node (AV node) as a wave front. The electri- artery (RCA) and vis-á-vis the AV node ischemia. This AV cal wave front then moves across the septum in a left-to-right node ischemia can manifest as type I heart block. The fi rst fashion, then to the bundle branches, and fi nally the wave indication of a type I heart block is a prolonged PR interval front radiates outward across the ventricular mass. Each of (PRI). Therefore, a Paramedic confronted with a possible these electrical events can be recorded, over time, on an ECG. IWMI would monitor the PRI in an IWMI for a possible The graphic representation of these events is the traditional heart block. PQRS complexes seen on an ECG. Finally, the Paramedic should consider the 12-lead ECG There is another way to look at the electrical event. as a whole. ECG changes in adjoining walls may be sugges- Instead of looking at depolarization in fragments of P, Q, R, tive of the extent and the evolution of the AMI. For example, and S, the Paramedic could look at the sum of these events. ST changes and T wave abnormalities across all of the pre- The sum of these electrical events would be the common cordial leads, from V1 to V6, are suggestive of an extensive direction of the electrical wave front called the mean electri- AMI. Such a pattern of ischemia could be suggestive of a cal vector (Figure 34-23). left main coronary artery occlusion.45 The implications of To explain vectorography in another way, these electrical left main coronary artery occlusion include acute pulmonary events could be likened to a battle front during a war. While edema (backward failure), cardiogenic shock (forward fail- an army may send out many patrols, some going in different ure), and sudden cardiac death (cardiac arrest). directions, the main objective of the army is to move the front A combination of Q waves, ST changes, and T wave forward. This common direction would be the army’s vec- abnormalities across one or more ventricular walls may be tor. Similarly, while there may be minor defl ections on the suggestive of an AMI later in its evolution. While every ECG, the major direction of the energy during depolarization STEMI has the potential for reversal, the prognosis in a late is toward the apex of the heart. This common direction, or evolution AMI is poorer and the morbidity higher. vector, of the energy of depolarization is called the heart’s Diagonostic ECG—The 12-Lead 777 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. – – – aVL aVR Left + –30° + Right superior + 0° I – Normal – – Right +30° + + + Mean +120° +60° Electrical Vector +90° III II Figure 34-23 Electrical vector. aVF Figure 34-25 Axis determination using the Hexaxial Reference System hexaxial reference system. –90° –120° –60° the depth of the S wave. An equiphasic wave would be nei- ther going toward the vector nor away from it, but would be AVR(+) –150° –30° AVL(+) perpendicular to it. Using that lead, the Paramedic would plot it on the hexaxial reference system (Figure 34-25). The lead represented on the perpendicular spoke would be the heart’s +180° 0° I(+) mean electrical axis in degrees. For example, if the equipha- sic QRS was Lead I, then the perpendicular axis would be 90 degrees. +150° +30° This method of axis determination, while very accurate, is cumbersome in the fi eld. An acceptable alternative is the +120° +60° Grant method. With the Grant method, the Paramedic would II(+) +90° II(+) AVF(+) refer to Lead I and Lead II only (Figure 34-26). If both leads are upright, then there is a normal axis deviation. If Lead I Figure 34-24 Hexaxial reference system. is upright but Lead II is primarily downward in defl ection, electrical axis. Any aberration from a normal electrical axis –90° could be indicative of disease (which is explained in more detail shortly). To help conceptualize the heart’s normal axis, and to help Extreme right Left axis determine if there is any axis deviation, an artifi cial construct axis deviation deviation called the hexaxial reference system was created. To create I I the hexaxial system, the limb leads were drawn around the heart and Lead I, the lead that is horizontal and on the right side, was assigned zero degrees and the left side 180 degrees. II II As the limb leads are part of Einthoven’s Triangle (an equilat- ±180° 0° Right axis eral triangle), then Lead II would be at 60 degrees and negative deviation Normal 120 degrees and Lead III would be at 120 degrees and nega- tive. The three axes are then all drawn into the middle of the I I heart and the three augmented leads overlaid with aVF at 90 degrees, aVL at negative 30 degrees, and aVR at 30 degrees II II and negative 150 degrees.

The resulting construct shows the heart divided into equal 30-degree segments (Figure 34-24). The traditional method of calculating the mean electri- +90° cal axis was to fi nd the most equiphasic lead of the frontal leads (I, II, III, aVR, aVL, and aVF). An equiphasic lead is Figure 34-26 Determination of axis using an QRS complex with an R wave that is equal in height to Lead I and Lead II. 778 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. then a left axis deviation is assumed. Alternatively, if Lead Differentiating VT from SVT I is primarily downward but the QRS in Lead II is upright, with Aberrant Conduction then it can be assumed it is a right axis deviation. If the QRS Paramedics (and other practitioners) often have diffi culty for both Lead I and Lead II is negatively defl ected, then the determining whether a fast rhythm with a wide QRS complex axis is called an extreme left axis deviation; nicknamed is ventricular tachycardia or supraventricular tachycardia with “no man’s land” because it represents extreme abnormal aberrant conduction. Some patients can tolerate a sustained depolarization. monomorphic ventricular tachycardia for a prolonged period of time, despite opinion that patients cannot tolerate ventricu- lar tachycardia (VT). Because the patient is tolerating what Street Smart appears to be a wide complex tachycardia of unknown etiol- ogy, the assumption is it must be supraventricular tachycardia Many 12-lead ECGs provide a reading of the axis, (SVT) with aberrant conduction. Some patients do develop a rate-related bundle branch block. listed as P-R-T axes. The Paramedic need only read The determination is important as treatments for SVT, the R axis and compare it to the hexaxial reference to such as calcium channel blockers, can lead to rapid patient determine the axis. deterioration if the rhythm is actually VT. Instead of trialing a medication to “see if it works,” at the risk of patient discom- fort and wasted time, a 12-lead ECG can provide the neces- sary information. Ventricular tachycardia occurs most often in patients Street Smart with acute cardiac ischemia or those with a cardiac history. The Paramedic should fi rst obtain a quick patient history, To reduce confusion, some Paramedics use their paying attention to antiarrythmic medications that indicate a thumbs to represent the QRS defl ection—Lead I on the previous history of cardiac dysrhythmia or medications that right hand and Lead II on the left hand. If Lead I is may predispose the patient to arrhythmias (proarrhythmic medications). upright (i.e., the right thumb is up and the left thumb Alternatively, supraventricular tachycardias often occur is down), then there is a left axis deviation. If both in otherwise healthy individuals. Some of these patients Lead I and Lead II are negative, then both thumbs may have a history of SVT or a diagnosis of WPW or LGL syndromes. are down. Next, the Paramedic should obtain a 12-lead ECG, pay- ing particular attention to axis deviation and R wave progres- sion. The fi rst step is to determine if the rhythm is regular. Axis Deviation Ventricular tachycardia is usually very regular. SVT with aberrancy is also usually regular unless the underlying cause Axis deviation is any time the heart’s axis is not normal. is an atrial fi brillation with a rapid ventricular response. If the Determining axis deviation is another means of observing rhythm is atrial fi brillation, then the ventricular response will many pathological conditions. Coupled with other physical be irregularly irregular. While regularity will not help differ- fi ndings, axis determination can help the Paramedic establish a entiate an interpretation of either VT or SVT, an irregularly diagnosis. For example, a right axis deviation which is abnor- irregular rhythm is suggestive of atrial fi brillation.48 mal can often suggest pulmonary pathologies such as pulmo- nary embolism and chronic obstructive pulmonary disease.46 Next, the Paramedic should examine the QRS morphol- ogy in V1. In ventricular tachycardia, the V1 lead will be an R A slight left axis deviation, from 0 to (-) 30 degrees, may wave, where typically there is no R wave. Looking across the be physiologic and seen in obese patients or women who are in chest leads, the Paramedic may also observe an S wave where their third trimester of pregnancy. A larger left axis deviation, typically there is no S wave. from (-) 30 to (-) 90 degrees, is often associated with left ven- In fact, if all of the QRS complexes in the chest Leads tricular hypertrophy, secondary to heart failure, inferior wall MI, or (in some cases) Wolff Parkinson White syndrome.47 V1 through V6 are in the same direction (a phenomena called concordance), the ECG interpretation favors VT. The direc- Of greater concern to the Paramedic is an extreme left tion of the QRS (the polarity) can be either positive or nega- axis deviation (>180 degrees) into “no man’s land.” While tive but should be in the same direction. conditions such as congenital transposition of the great ves- Next, the Paramedic should look at Lead I and Lead sels and dextrocardia can produce this, extreme left axis II. If both leads are negative, or the R vector on the 12-lead deviation in the normal heart is suggestive of ventricular ECG reads between (-) 90 degrees and (-) 180 degrees (i.e., tachycardia. During ventricular tachycardia, the electrical extreme left axis deviation), then the interpretation of VT is source is in the ventricle and the wave front runs backward supported. through the conduction system. Diagonostic ECG—The 12-Lead 779 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Table 34-8 Comparison of VT vs. SVT Paramedic does not usually have access to lab results, the with Aberrancy patient’s history may suggest the potential for electrolyte dis- turbances. For example, patients in end-stage renal disease Supraventricular may experience elevation of potassium levels while those Ventricular Tachycardia Tachycardia patients receiving diuretics may have a decreased level of • History of ischemia • Healthy individual potassium unless they receive potassium supplementation. • Proarrythmic medications • History of SVT A normal potassium level, between 3.5 mEq/L and • Regular or irregular rhythm • Regular or irregular rhythm 4.5 mEq/L, is important for optimum cardiac cell function. If • Dissociated P wave activity • P waves before each QRS the patient is hypokalemic (i.e., serum potassium less than 3.5 • Concordance in the chest leads • R wave progression mEq/L), then the patient may be prone to decreased inotropy. • In V1 ( MCL1), R wave, Rr’, QR, RS • In V1 (MCL1), rSR’ This can lead to generalized weakness or malaise, and/or dys- rhythmias such as atrial fl utter and bradycardia. • In V6 (MCL6), rS, QS, QR • In V6 (MCL6), qRs Causes of hypokalemia are numerous and include vom- • QRS duration of 0.16 sec or more • QRS duration > 0.12 but iting, aggressive gastric suctioning, diarrhea (secondary to < 0.16 sec infectious diseases), or abuse of potassium-wasting diuret- • Initial notching or slurring of QRS • Absent or ending slurring ics such as furosemide. With hypokalemia, the 12-lead ECG of QRS may show T wave fl attening, ST-segment depression, and/or • Axis of –90 to –180 degrees • Axis of –90 to 180 U wave development.49,50 Hypokalemia is often associated with low magnesium Finally, the Paramedic should observe the 12-lead ECG levels or hypomagnesemia (Figure 34-27). Hypomagnesemia for the presence of P waves. Atrial depolarization still occurs may predispose the patient to a form of polymorphic ven- in VT, independent of the ectopic ventricular pacemaker. tricular tachycardia called torsades de pointes.51 Because of the independent atrial and ventricular activity Albuterol is a bronchodilator but also drives potas- (i.e., atrial–ventricular dissociation), P waves will randomly sium into the cells. Aggressive use of albuterol (i.e., stacked appear throughout the 12-lead ECG. P waves that appear reg- treatments) may cause changes in cellular uptake of potas- ularly in front of a QRS suggest a supraventricular ectopic sium, putting the patient at risk for low potassium levels and pacemaker (Table 34-8). dysrhythmias. Perhaps more problematic for the Paramedic may be Miscellaneous Effects on the ECG hyperkalemia. A serum potassium level above 4.5 mEq/L is Electrolyte abnormalities, particularly potassium, can cause considered hyperkalemia. One of the most common causes changes in the appearance of the 12-lead ECG. While the of hyperkalemia is kidney failure. Patients who are on kidney 2.8 2.5 2.0 1.7 Hypokalemia 6.5 7.0 8.0 9.0 Hyperkalemia Figure 34-27 ECG changes associated with hypokalemia and hyperkalemia. 780 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. dialysis are at obvious risk of hyperkalemia prior to dialy- An acute rise in intracranial pressure secondary to sub- sis. Other at-risk patients include patients with diabetes who arachnoid hemorrhage, intracerebral bleed, or an epidural are experiencing diabetic ketoacidosis, patients with severe bleed may lead to wide and deeply inverted T waves in the burns, patients with crush injury, and those patients with chest leads.53–55 The Paramedic’s attention is likely focused acute tubular necrosis secondary to shock. on other more urgent matters during one of these events. The common ECG alterations seen in hyperkalemia However, 12-lead ECG evidence, if obtained, may be useful are changes in the T wave. At potassium levels greater than at the emergency department. 4.5 mEq/L but less than 6.5 mEq/L, the T wave appears tall and Hypothermia affects all cellular functions and can also peaked and is best seen in inferior leads (Lead II and Lead III). cause changes in the ECG. When a patient is hypothermic, all As the potassium level continues to climb toward 8 Eq/L, the of the interval durations (i.e., PR, QRS, and QT) lengthen and QRS starts to widen and a left axis deviation may be appreci- positive defl ections at the J point, or point where the ventricu- ated. Finally, as the potassium level climbs above 8 mEq/L, the lar complex ends and the ST segment begins, become notice- P waves all but disappear and the QRS starts to fl atten into a able. These defl ections are in the same direction (polarity) as sine wave confi guration. It is at this time the patient’s cardiac the QRS and are termed Osborn waves (sometimes called the output has dropped precipitously and the patient is at risk for camel-hump sign). The Osborn wave is seen in all leads, but ventricular fi brillation or asystole. is more prominent in the inferior limb leads. The size of the Arrhythmias caused by hyperkalemia are very diffi cult to Osborn waves correlates directly with the degree of hypo- treat with defi brillation or the usual emergency drugs without thermia. Osborn waves are often diffi cult to discern because lowering the serum potassium level. Calcium chloride, calcium of artifact from muscle tremors (Figure 34-28), but are seen gluconate, or sodium bicarbonate, all competitive electrolytes, in 80% of patients with hypothermia (below 33°C/91.4°F).56 may be used to lower potassium levels. Alternatively, serial Finally, pericarditis, an infl ammation between the treatments with Albuterol may help to treat mild to moderate pericardium and the epicardium, can cause chest pain hyperkalemia. In severe cases, it may be necessary to adminis- and 12-lead ECG abnormalities. Initially, the

Paramedic ter 50% dextrose with short-acting insulin.52 The insulin helps may be led to believe that the chest pain is secondary to drive both glucose and potassium into the cells. to acute coronary syndrome. However, nitrates are not use- ful in treating the pain of pericarditis, so it is important for the Paramedic to seek historical clues to the diagnosis of pericarditis (i.e., fevers, etc.) as well as ECG evidence. Street Smart The infl ammation that occurs between the sac surround- ing the heart and the epicardium leads to swelling which Calcium is needed for regular cell function. Loss of puts some pressure on the myocardium. The myocardium calcium (serum calcium levels less than 8.5 mg/dL) cannot repolarize as it normally does due to the swelling, so there are T wave changes. The T will become pointed or hypocalcemia is rare. Typical causes of calcium and tall (similar to a hyperacute T wave found in an MI). disturbances are chronic diseases. The effect of However, the changes tend to occur in all leads rather than calcium is seen on the QT interval. Hypocalcemia within contiguous leads only, leading the Paramedic to sus- pect other causes for the chest pain, such as pericarditis. causes a widened QT interval whereas an elevated serum calcium causes a short QT interval. To Evaluation remember that calcium is related to QT, the One of the advantages of the 12-lead ECG is its ability to Paramedic need only remember that QT interval is predict the clinical progression of the patient’s disease if corrected for heart rate and recorded on the 12-lead left unchecked. For example, in the case of a patient with an anterior wall myocardial infarction (AWMI), the patient may ECG as such (i.e., QTc). The little c could represent eventually develop cardiogenic shock secondary to lost myo- calcium, to remind the Paramedic of other causes of cardial function. In this case, the patient had an IWMI that prolonged/shortened QT intervals. could, predictably, either extend to the mitral valve (causing J wave Extra-Cardiac Causes of ECG Changes Potentially devastating extra-cardiac pathologies, such as I intracranial hemorrhage, hypothermia, and pericarditis, can also cause changes on the 12-lead ECG. While not pathogno- monic for these pathologies, they are another sign to be added Figure 34-28 Osborn wave secondary to to the symptom complex for diagnosis. hypothermia. Diagonostic ECG—The 12-Lead 781 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Figure 34-29 Lead placement for a 15-lead ECG, which is helpful in assessing the right ventricle. mitral valve regurgitation) or extend into the right ventricle. It 15-Lead ECG is estimated that 50% of IWMI extend into the right ventricle, with a resultant loss of preload. An additional diagnostic test available to the Paramedic if the Paramedic suspects right ventricular involvement is the 15-lead ECG.57 The electrode placement for a 15-lead ECG will place positive electrodes onto the right side of the chest Street Smart and view the right ventricle. Locations for these electrodes are the 5th right intercostal The right ventricle essentially primes the pump (the space at the midclavicular line, 5th right intercostal space ante- rior axillary line, and 5th right intercostal space at midaxillary. left ventricle). Loss of right ventricular function, The corresponding V4 to V6 wires from the left chest elec- secondary to myocardial injury, can lead to profound trodes are switched over to the right electrodes and the ECG is hypotension. For this reason, some Paramedics rerecorded (Figure 34-29). The repeated ECG is marked right perform a 15-lead ECG to identify right ventricular chest leads or V4R, V5R, and V6R. involvement before administering vasodilators such as nitroglycerin. 782 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. The diagnostic 12-lead electrocardiogram is a useful tool in the Paramedic’s assessment tool box with the potential to improve patient outcome by early detection of cardiac abnormalities. This is especially true in situations where the patient presents with an acute ST elevation myocardial infarction, where the patient can be triaged to the appropriate hospital, or in cases of dynamic changes in the ECG that change with treatment, uncovering underlying cardiovascular disease. Key Points: • Death from AMI remains a national health problem. • Understanding an acute myocardial infarction • requires an understanding of penumbra. Aggressive prehospital treatment including obtaining and interpreting a 12-lead ECG can • Additional ECG evidence, such as new onset left favorably impact patient mortality and morbidity. bundle branch block (LBBB) and reverse R wave • progression (RRWP), are important in supporting Paramedics must have a higher index of suspicion the diagnosis of myocardial infarction. with patient populations that may present with atypical cardiac symptoms. • Some 12-lead ECGs do not show acute changes. • The Paramedic should focus on treating the patient A regular ECG uses standard limb leads, augmented based on history. limb leads, and precordial leads. • • There are numerous extra-cardiac causes to ECG The regular ECG allows for inferior, anterior, abnormalities. and lateral views of the left ventricle, as well as combinations. • 12-lead ECG interpretation takes a disciplined • approach that gathers all the pertinent information Accurate 12-lead ECG requires proper patient to prevent premature interpretation. preparation including standardized electrode placement. • Based on the 12-lead ECG interpretation and the • patient history, the Paramedic can make a fi eld A 12-lead ECG is printed in a standard diagnosis. confi guration. • • Additional information is also available from the Viewing a specifi c combination of leads, called 12-lead ECG that can lend insight into other health contiguous leads, allows correlation to specifi c conditions. ventricular walls. • • The 12-lead ECG can help differentiate ventricular Based upon coronary artery anatomy, ECG changes tachycardia (VT) from supraventricular tachycardia. in contiguous leads permit Paramedics to estimate damage in specifi c arteries. • The addition of three right-sided leads can help • identify right ventricular AMI. Estimation of damage in specifi c arteries permits prognosis and planning. • Early detection of MI, via 12-lead ECG, and rapid transportation to an interventional cardiac care center can lead to better patient outcomes. Diagonostic ECG—The 12-Lead 783 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Review Questions: 1. Why is Paramedic use of 12-lead ECG the fi rst 5. Where are leads placed for a right-sided ECG? step in a critical pathway for patients with acute 6. What are some atypical presentations of acute coronary syndrome? coronary syndrome that might require the 2. What are the key elements necessary for an Paramedic to obtain a 12-lead ECG? accurate acquisition of a 12-lead ECG? 7. List the ECG changes that occur as an acute 3. List the ECG abnormalities associated with an myocardial infarction evolves. inferior wall MI, anterior wall MI, and lateral 8. What is penumbra? wall MI. 9. What is the signifi cance of a new onset left 4. Which leads are affected on an ECG of a bundle branch block? patient experiencing an inferolateral MI? An 10. List potential causes of T wave abnormalities. anterolateral MI? Case Study Questions: Please refer to the Case Study at the beginning of the 2. How can an early ECG assist the Paramedic in chapter and answer the questions below: determining appropriate patient destination? 1. What is the benefi t of a baseline ECG? References: 1. Pope JH, Selker HP. Diagnosis of acute cardiac ischemia. Emerg and thrombolysis by prehospital care providers. Can J Cardiol. 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Electrocardiographic markers of leads in the ED chest pain patient: right ventricular and posterior abnormal left ventricular wall motion in acute subarachnoid leads. Am J Emerg Med. 2003;21(7):563–573. hemorrhage. J Neurosurg. 1995;83(5):889–896. 786 Foundations of Paramedic Care Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. A&O Alert and oriented ATP Adenosine triphosphate ABC Airway, breathing, circulation ATSDR Agency for Toxic Substances and Disease ABF American Burn Foundation Registry ABG Arterial blood gas ATV Automatic transport ventilator AC Alternating current AV Atrioventricular node AC Antecubital avdp Avoir de pois ACE Angiotensin-converting enzyme AVPU Alert, voice, pain, unresponsive ACEP American College of Emergency Physicians AWMI Anterior wall acute myocardial infarction ACLS Advanced cardiac life support BAAM Beck airway airfl ow monitor ACS Acute coronary syndrome BARNACLE Benefi ts, alternatives, risks, nature, ACTH Adrenocorticotropic hormone answers, consents, lacks treatment, explanations ADA Americans with Disabilities Act BIAD Blind insertion airway devices ADEA Age Discrimination in Employment Act BiPAP Bilevel positive airway pressure ADH Antidiuretic hormone BLS Basic life support ADL Activities of daily living BOLO Be on the lookout ADP Adenosine diphosphate BP Blood pressure AED Automated external defi brillator BPG Blood pressure gas AEIOU-TIPS Alcohol, epilepsy, insulin, overdose, BPH Benign prostate hypertrophy uremia, trauma, infection, psychiatric, stroke BPM Beats per minute AEMT Advanced emergency medical technician BSA Body surface area AHA American Heart Association BSI Body substance isolation AHF Antihemophiliac factor BTE Behind the ear AICD Automated implantable cardioverter defi brillators BURP Backward, upward, rightward pressure AIDS Acquired immune defi ciency syndrome BVM Bag-valve mask AIA Aspirin-induced asthma CAAHEP Commission on the Accreditation of Allied AIR Allergies, intended effect, reasonable risks Health Education Programs AIV Anterior interventricular CAAS Commission on the Accreditation of Ambulance ALJ Administrative law judge Services ALS Advanced life support CABG Coronary artery bypass graft AM Amplitude modulation CAD Computer-assisted dispatch AMA Against medical advice CAD Coronary artery disease AMA American Medical Association CAMP Cyclic adenosine monophosphate AMI Acute myocardial infarction CAST Cardiac arrhythmia suppression trial AMPLE Allergies, medications, past medical history, CBC Complete blood count last meal, events CBF Cerebral blood fl ow ANI Automatic number identifi cation CC Chief concern ANSI American National Standards Institute cc Cubic centimeter APA American Psychiatric Association CCU Coronary care unit APAP Acetaminophen CDC Centers for Disease Control and Prevention APCO Association of Public Safety Communications CFR Code of Federal Regulations Offi cials CHART Chief complaint, history, assessment, Rx APHA American Public Health Association [prescription], treatment ARC American Red Cross CHARTIE Chief complaint, history, assessment, Rx ARDS Adult respiratory distress syndrome [prescription], treatment, intervention, evaluation ARF Acute renal failure CHB Complete heart block ASA Acetylsalicylic acid CHEATED Chief concern/complaint, history, ASTM American Society of Testing and Materials examination, assessment, treatment, evaluation, AT&T American Telegraph and Telephone disposition ATLS Advanced trauma life support CHF Congestive heart failure Acronyms 787 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. CINAHL Cumulative Index to Nursing and Allied Health ECF-A Eosinophil chemotactic factor of anaphylaxis CIRT Critical incident response team ECF Extracellular fl uid CISD Critical incident stress debriefi ng ECG Electrocardiogram CMS Centers for Medicaid and Medicare Services ED Emergency department CNS Central nervous system EDD Esophageal detection devices CoAEMSP Committee on Accreditation of Educational EDD Expected date of delivery Programs for the EMS Professions EDRF Endothelial-derived relaxing factor COE Council of Experts EDV End diastolic volume COHgb Carboxyhemoglobin EGTA Esophageal gastric tube airway COMSPEC Communications specialists EHF Extremely high frequency COMT Catechol-O-methyltransferase EJV External jugular vein COP Colloidal osmotic pressure ELF Extremely low frequency COPD Chronic obstructive pulmonary disease EMD Emergency medical dispatch CO2 Carbon dioxide EMG Electromyographic signal CPAP Continuous positive airway pressure EMI Electromagnetic interference CPP Cerebral perfusion pressure EMLA Eutectic mixture of local anesthetics CPR Cardiopulmonary resuscitation EMR Emergency medical responder CPS Cycles per second EMS Emergency Medical Services CQI Continuous quality improvement EMSC EMS for children CRF Corticotrophin-releasing factor EMT Emergency medical technician CSF Cerebrospinal fl uid ENA Emergency Nurses Association CT Central terminal ENS Emergency notifi cation system CTZ Chemoreceptor trigger zone EOA Esophageal obturator airway CVA Cerebrovascular accident EOM Extraocular movements CVAD Central venous access devices EOMI EOM intact CVP Central venous pressure EPIC Eliminate preventable injuries of children Cx Circumfl ex EPS Extrapyramidal symptoms DARE Data, action, response, evaluation ER Emergency room DC Direct current ERIC Educational Resources Information Center DEA Drug Enforcement Administration ERV Emergency response vehicle DEEDS Data Elements for Emergency Departments ET Endotracheal DG Dorsogluteal ETA Estimated time of arrival DHHS Department of Health and Human Services ETC Esophageal tracheal Combitube DIC Disseminated intravascular coagulation EtCO2 End-tidal carbon dioxide levels DKA Diabetic ketoacidosis EtOH Ethanol DNAR Do-not-attempt-resuscitation ETT Endotracheal tube DNR Do-not-resuscitate EVO Emergency vehicle operator DO Designated offi cer FAX Facsimile DO Doctor of Osteopathic Medicine FCC Federal Communications Commission DOPE Displacement, obstruction, pneumothorax, FDA Food and Drug Administration equipment FDNY Fire Department of New York DOT Department of Transportation FEMA Federal Emergency Management Agency DP Dorsalis pedis FF Firefi ghters DPAHC Durable power of attorney for health care FFP Fresh frozen plasma DPI Dry powder inhalers FHS Fetal hydantoin syndrome DRG Diagnosis-related group FLSA Fair Labor Standards Act DSD Dry sterile dressing FM Frequency modulation DSMB Data and Safety Monitoring Board FMLA Family and Medical Leave Act DSM-IV Diagnostic and Statistical Manual, fourth FUO Fever of unknown origin edition GABA Gamma aminobutyric acid DTR Deep tendon refl ex GCS Glasgow Coma Scale Dx Diagonal GERD Gastroesophageal refl ux disease EAS Emergency alert system GTT Drops 788 Acronyms Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. HACE High-altitude cerebral edema LEO Law enforcement offi cer H&H Hematocrit and hemoglobin LEO Low Earth orbit HAPE High-altitude pulmonary edema LES Lower esophageal sphincter HAPI-SOCS History, activity, pain, infection, smoker, LF Low frequency orthopnea, cough, sputum LGL Lown-Ganong-Levine Hb Hemoglobin LMA Laryngeal mask airway HBV Hepatitis B LMP Last menstrual period HCFA Health Care Finance Administration LMR Land mobile radio HCV Hepatitis C LMWH Low-molecular weight HDL High-density lipoproteins LOS Line of sight HELP Head elevated laryngoscopic position LOX Liquid oxygen HF High frequency LPM Liters per minute HFNC High-fl ow nasal cannula LQTS Prolonged QT syndrome HIPAA Health Insurance Portability and Accountability LR Lactated Ringer’s Act LSD Lysergic acid diethylamide HIV Human immunodefi ciency virus MAC Membrane attack complex HMO Health maintenance organization MAO Monoamine oxidase HOH Hard of hearing MAP Mean arterial pressure HPI History of present illness MCI Multiple casualty incident HPV Human papillomavirus MCL1 Modifi ed chest Lead 1 HSV Herpes simplex virus MDI Metered dose inhaler HTLV Human T-lymphotropic virus MDT Mobile data terminals IAFC International Association of Fire Chiefs MER Medication error reporting IAFF International Association of Firefi ghters MeSH Medical subject headings I&D Incision and drainage MetHgb Methemoglobin ICD-10 International Classifi cation of Diseases, 10th MF Medium frequency Revision MFI Medication-facilitated intubation ICF Intracellular fl uid MHS Marine Hospital Service ICP Intracranial pressure MI Myocardial infarction ID Internal diameter MMR Measles, mumps, rubella ILMA Intubating LMA MMWR Morbidity and Mortality Weekly Report ILO International Labor Organization MODS Multiple organ dysfunction syndrome IM Intramuscular MOI Mechanism of injury IN SAD CAGES Interest, sleep disorder, appetite, MRT Modulated receptor theory depression, concentration, activity, guilt, energy, MSU Mobile subscriber units suicidal ideation MVC Motor vehicle collision IND Investigational new drug NAD No

apparent distress IO Intraosseous NAEMSE National Association of EMS Educators IOM Institute of Medicine NAEMSP National Association of Emergency Medical IRB Institutional Review Board Services Physicians ITE In the ear NAEMT National Association of Emergency Medical IU International unit Technicians IV Intravenous NAP Narrative, assessment, plan of treatment IVAD Implanted vascular access device NASEMSO National Association of State EMS Offi cials IWMI Inferior wall myocardial infarction NEMSES National EMS Education Standards JV Jugular vein NEMSIS National EMS Information System JVP Jugular venous pressure NEMSSOP National EMS Scope of Practice KVO Keep vein open NF National formulary LAD Left anterior descending coronary artery NG Nasogastric LBBB Left bundle branch block NHANES National Health and Nutrition LCA Left coronary artery Examination Survey LDL Low-density lipoproteins NHR Natural hormone replacements LEMON Look, evaluate, Mallampati, obstruction, NHTSA National Highway Traffi c Safety neck mobility Administration Acronyms 789 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. NIDDM Non-insulin dependent diabetes mellitus PMI Point of maximal intensity NIH National Institute of Health PO “Per os” or by mouth NKDA No known drug allergies POLST Physician’s order of life-sustaining treatment NMBA Neuromuscular blocking agent POMR Problem-oriented medical recordkeeping NO Nitric oxide POS Point of service NP Nasopharyngeal PPE Personal protective equipment NPH Neutral protamine Hagedorn PPO Preferred provider organization NPO Nothing by mouth PRBC Packed red blood cells NRB Nonrebreather PRI PR interval NREMT National Registry of Emergency Medical PSAP Public safety access point Technicians PSDA Patient Self-Determination Act NRFM Nonrebreather face mask PSI Pounds per square inch NRHA National Rural Health Association PT Prothrombin times NS Normal saline PTL Pharyngeal-tracheal lumen NSAID Nonsteroidal anti-infl ammatory drugs PTSD Post-traumatic stress disorder NSC National Standard Curriculum PTT Partial prothrombin time NSR Normal sinus rhythm PVC Polyvinyl chloride NSTEMI Non-ST-segment elevation myocardial PVC Premature ventricular contractions infarction PVR Peripheral vascular resistance OG Orogastric PVS Persistent vegetative state OJT On the job QA Quality assurance OPA Oropharyngeal Airway QI Quality improvement OPQRST AS/PN Onset, provocation, quality, QRS Quick response system radiation, severity, timing, associated symptoms, RAS Reticular activating system pertinent negatives RBBB Right bundle branch block OSHA Occupational Safety and Health Administration RCA Right coronary artery OTC Over the counter RCT Randomized clinical trial PaCO2 Arterial pressure of carbon dioxide REM Rapid eye movement PAD Public access defi brillation RF Radio frequency P&S Physicians and surgeons RFR Radio frequency radiation PCA Patient-controlled analgesia RIC Rapid infusion catheter PCP Primary care provider RMA Refusal of medical assistance PCR Patient care report RMP Resting membrane potential PCS Personal cellular service ROSC Return of spontaneous circulation PCVC Percutaneous central venous catheters RR Respiratory rate PDA Personal digital assistant RRWP Reverse R wave progression PDCA Plan-do-check-act RSI Rapid sequence intubation PDR Physician’s Desk Reference SA Sinoatrial PE Physical examination SAFE-R Stimulation reduction, acknowledgement, PE Pulmonary embolism facilitate, explain, restore PEA Pulseless electrical activity SAMPLED Signs, allergies, medications, past medical PEARLS Partnership, empathy, apology, respect, history, last of something, events, directives legitimization, support SARS Severe acute respiratory syndrome PEEP Positive end expiratory pressure SCD Sudden cardiac death pH Potential hydrogen SCT Specialty care transport PHI Personal (or protected) health information SHF Super high frequency PHS Public health service SI Le Systeme Internationale d’unites PICC Peripherally inserted central catheter SIR Special incident report PIER Public information, education, relations SIRS Systemic infl ammatory response syndrome PIM Potentially infectious materials SLF Super low frequency PIO Public information offi cer SLUDGEM Salivation, lacrimation (tearing of the PL Private line eyes), urination, defecation, gastrointestinal pain, PM Preventative maintenance emesis, miosis PMH Past medical history SMS Slow muscle stimulating 790 Acronyms Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. SOAP Subjective, objective, assessment, plan TRALI Transfusion-related acute lung injury SP Septal perforators TROPO Tropospheric SRS-A Slow acting substances of anaphylaxis TTJV Transtracheal jet ventilation SSCP Substernal chest pain TV Tidal volume SSM System status management UCLA University of California at Los Angeles SSRI Selective serotonin re-uptake inhibitors UHF Ultra high frequency STD Sexually transmitted disease ULF Ultra low frequency STEMI ST-segment elevation myocardial infarction USP United States Pharmacopeia SVN Small volume nebulizer UVC Umbilical venous access SVT Supraventricular tachycardia VHF Very high frequency SWAT Special weapons and tactics VL Vastus lateralis TACO Transfusion-associated circulatory overload VLDL Very-low density lipoproteins TBI Traumatic brain injury VLF Very low frequency TBW Total body weight VT Ventricular tachycardia TCA Tricyclic antidepressants WEMT Wilderness EMT TEMS Tactical EMS WFPHA World Federation of Public TKO To keep open Health Associations TNT Trinitrin WHO World Health Organization TOT Turned over to WO Wide open TPA Tissue plasminogen activator WPW Wolff-Parkinson-White syndrome Acronyms 791 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Abandonment Situation in which a Paramedic walks opposite direction to that used for normal diffusion, away from or discontinues care for a patient without which requires an expenditure of energy. turning over care to another provider who has the Activities of daily living (ADL) The everyday events same or higher level of training. people perform in the course of their life, such as Abnormal automaticity Spontaneous impulses eating, dressing, driving, performing personal hygiene, generated in cardiac muscle that may interfere with and generally caring for themselves. the SA node’s contraction-regulating impulses. Act-utilitarianism An approach to ethical decision Abrasions An irritated area on the skin caused by making in which the Paramedic weighs the outcomes wearing or rubbing away by friction. or consequences of performing the act against not Abscess A localized collection of pus surrounded by performing the act and then makes a decision that infl amed tissue. maximizes the intrinsic good. Absolute bradycardia A sinus rhythm with a rate Acute coronary syndrome (ACS) A complex below 60 bpm. of symptoms associated with the continuum of Abstract An abbreviated summary that hits a research cardiovascular disease, emphasizing its morbidity (and study’s highlights. more importantly, its mutability) and not simply its Accessory muscles Muscles recruited to assist with mortality. body functions when the normal muscles used for Acute hemolytic reaction A serious bodily that task are inadequate. For example, in respiratory response to a transfusion that most often occurs distress, accessory muscles may be used to help as a result of an A-B-O blood type incompatibility, expand the rib cage, allowing the patient to inhale. which leads to agglutination and hemolysis of the Accessory pathway A congenital abnormal cardiac transfused blood. electrical pathway that may be indicated by a short Acute myocardial infarction (AMI) Death of cardiac PR interval. muscle tissue. Acetylcholine The chief neurotransmitter released Acute renal failure (ARF) The net effect of prolonged into the synapse from the nerve’s presynaptic hypoperfusion, leading to a reduction in the kidneys’ membrane during neurotransmission. ability to function. Acetylcholinesterase A chemical that breaks down Acute respiratory distress syndrome (ARDS) A acetylcholine. serious reaction to various injuries that involve the Acid A substance with a pH value less than 7; a lungs. molecule that has a proton that is not orbited by a Acute respiratory failure Dysfunction within the paired electron. lungs that impairs respiration. Acid load Excessive amounts of acid in the tissues to Acute traumatic stress An unexpected and sudden the point that tissues are acidotic. stressful event which is unlike the stress of day-to-day Acidemia Condition in which the amount of hydrogen EMS and understandably requires a different approach atoms in an arterial blood gas sample is below 7.35. to relieve. Acidosis Excessive acid in a body system that can Adenosine triphosphate (ATP) The chemical energy have a profound effect upon the body’s uptake, source in a cell used to power the rest of the cell’s distribution, and the effectiveness of medications functions. administered. Administrative law judge (ALJ) One who decides Acknowledging Responding to a patient’s answer cases involving violations of a department’s to a question with a positive reply, either verbal or regulations. nonverbal, that encourages further dialogue. Adrenergic transmission The transmission of Actionable Determination if a claim can be the a nervous system signal using adrenaline as the basis for a lawsuit. To be actionable , a claim must neurotransmitter. generally have the four elements of a tort. Advanced directives Written declarations of Action potential A stimulus that raises the resting patient intent during specifi c circumstances, which membrane potential above a specifi c threshold. are designed to provide guidance when a patient is Active transport The movement of a chemical threatened with living in a persistent vegetative state substance through a gradient of concentration in the or being affl icted with a terminal illness. 792 Glossary Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Advanced emergency medical technician (AEMT) Alkalemia Condition in which the amount of hydrogen An EMS professional trained to administer a limited atoms in an arterial blood gas sample is above 7.45. number of drugs and perform skills that have been Alkaloids Nitrogenous chemicals which are alkaline in shown to positively impact patient survival. nature and often chemically combined with acids to Advanced life support (ALS) Additional skills create water-soluble salts, such as morphine sulfate or and equipment offered by Paramedics over and atropine sulfate. above basic life support, such as intubation and Allergic reactions A bodily response that occurs when ventilation. exposed to a certain substance, ranging from sneezing Adverse drug reaction An unwanted or harmful and rashes to severe complications. biological response to a drug that creates a Alpha-adrenergic blockers Competitive blockers subsequent negative impact upon the patient’s health. occupying the adrenergic receptor and preventing the Aerobic metabolism The step in the metabolism catecholamine drug from attaching to the adrenergic process in which the cell uses oxygen to create ATP receptor. Alpha-adrenergic blockers can be divided as from glucose. either long-acting and short-acting or competitive and Affi davit A sworn written statement which attests to noncompetitive. facts that pertain to a legal case. Alpha1 adrenergic receptors Sympathetic Affi nity An attraction to or liking of something. neuroreceptors primarily involved with excitation. Against medical advice (AMA) Situation in which They are located in the peripheral vascular beds, on patients refuse medical care in opposition to all logic the arteriole side, and control the sphincters (round when confronted with a clear and immediate danger muscles) of the bladder, intestine, and the iris of the to their health. pupil. Ageism A stereotypical view of the elderly as frail or Alpha2 adrenergic receptors Sympathetic feeble. neuroreceptors found in the gastrointestinal tract Age of majority The legal age a person must be in where they decrease bowel motility, via relaxation of order to consent to a medical procedure; 18 years of the smooth muscles within the intestinal walls. age in most states. Alternative hypothesis A result in a research study Agglutination Clumping together of red blood cells. indicating the treatment is a plausible explanation for Agonist A drug or other chemical that can combine a change. with a receptor on a cell to produce a physiologic Alternative medicine Techniques other than reaction typical of a naturally occurring substance. traditional

western medicine people may attempt Airlock A technique in which the Paramedic injects for a more natural treatment, such as use of mega- a small bubble of air into the injection, essentially vitamins, therapeutic massages, chiropractic sealing off the drug below from leaking out to the medicine, and acupuncture. subcutaneous tissues above. Alveoli A large collection of small sacs in the lung that Akinetic State of being without motion. provides a larger surface area for gas exchange than if Alarm A signal on an ECG machine that indicates, via the lung were made up of a single large sac; singular visible and/or audible signal, that a patient’s heart is alveolus. rate is above or below a certain rate. Ambulatory Able to walk. Alarm stage The fi rst stage of the general adaptation Americans with Disabilities Act (ADA) A law that syndrome, during which the body responds to the prohibits discrimination based on disability in hiring, stressor via the central nervous system. promoting, training, and retiring. Alert report A notifi cation sent to the receiving AMPLE A mnemonic used to determine a patient’s medical facility about an incoming patient arrival. The past medical history, consisting of questions about information in the alert report is brief and concise: allergies, medications, past medical problems, last age, sex, chief complaint, mental status, vital signs, oral intake, and events preceding the incident. treatments in progress, and an estimated time of Amplitude modulation (AM) When modulating an arrival (ETA). audio signal, changing the wave’s height. Algorithm A logic tree in fl owchart format that simply Anaerobic metabolism The phase of glucose states: if this, then do that; if not this, then do metabolism that does not utilize oxygen, in which the this other thing. Algorithms can be useful during an cell changes glucose into pyruvate acid, which is in emergency when time is of the essence. turn converted into lactic acid. Algor mortis The body’s natural cooling. As the body’s Analgesia A condition where the patient does not feel metabolic processes cease, so does the production pain, yet remains conscious. More importantly, the of heat. patient retains his or her protective refl exes. Glossary 793 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Analgesics Medications that relieve pain by inhibiting Artifact A disturbance in the isoelectric line of the synthesis or release of prostaglandins or an ECG as a result of outside interference with the stimulating opiate receptors (opiate agonists). signal. Anaphylactic response An exaggerated immune Arytenoid One of three separate cartilaginous response that can lead to severe airway compromise structures in the aryepiglottic folds that are attached and/or cardiovascular collapse secondary to relative to each other and other structures by ligaments as hypovolemia. well as the intrinsic and extrinsic muscles of the Anaphylatoxins Substances that increase the larynx. degranulation of mast cells and attract other white Ascites Accumulation of fl uid in the peritoneal cavity. blood cells (leukocytes) to the site. Assault An intentional tort involving a threat of Anasarca Total body edema. violence, either physical or verbal. Anemia Condition in which the blood is lacking red Asthma A chronic lung disorder marked by recurrent blood cells, hemoglobin, or volume. airway obstruction and labored breathing. Anemic hypoxia A low hematocrit, or other red blood Ataxia A disequilibrium in one’s walk that resembles cell abnormality, that can lead to oxygen deprivation a drunkard’s stagger. at the cellular level. Atherosclerosis The underlying pathology of Anesthesia A lack of sensation, painful or otherwise. coronary artery disease, which starts as a streak of Anesthetic drugs primarily induce anesthesia by fat (cholesterol) on the walls of an artery. The fat interfering with or blocking nerve conduction. infi ltrates into the wall of the artery and forms Angulated Describes an extremity where the bone a fatty lesion. is obviously fractured and displaced at an abnormal Atrial diastole State during the cardiac cycle in which angle. the atria are at rest. Anorexia nervosa A psychiatric illness involving Atrial kick The active contribution of blood to the problems with self-image characterized by self- ventricle by the atria during the cardiac cycle. starvation and bulimia. Atrial systole State in which the atria contract during Antagonist A drug or other chemical that interferes the cardiac cycle. with the physiological action of another substance, Atrioventricular (AV) node A small mass of especially by combining with and blocking its nerve specialized cardiac muscle fi bers, located in the receptor. wall of the right atrium of the heart, that receives Antecubital fossa (AC) A triangular cavity of the heartbeat impulses from the sinoatrial node and elbow joint that contains a tendon of the biceps, the directs them to the walls of the ventricles. median nerve, and the brachial artery. Atropine A parasympathetic blocker that decreases Anticholinergics Drugs that block acetylcholine from vagal response. binding to either muscarinic or nicotinic receptors and Augmented leads A modifi ed unipolar limb type stop parasympathetic activity. made from combining the lead type and the positive Antigens Foreign proteins found in bacteria. electrode location (i.e., augmented voltage right or Antimetabolites Drugs that prevent enzymes from aVR, augmented voltage left or aVL, and augmented stimulating a cell’s metabolism. voltage foot now called aVF). Antitussive A cough suppressant. Auscultation An assessment performed by listening, Anoxia Hypoxia of such severity that permanent typically using a stethoscope. damage results. Autoimmune response An immune response Anxiolytics CNS depressants that reduce apprehension, triggered by some infections that causes damage to fear, and anxiety. the host. Aortic stenosis A condition in which the leafl ets of Automatic answers Short, single-word responses the aortic valve become scarred over time and the such as “yes” or “no” given in reply to closed-ended pathway through the valve narrows. questions. Apical pulse The pulse rate at the chest. Automaticity A cell’s ability to generate its own action Apologize An admission of fault or error accompanied potential. by a request for acceptance of that admission. Automatic transport ventilators (ATV) Mechanical Apoptosis A normal physiological process in which old devices that deliver a specifi ed volume of or damaged cells are destroyed so new ones can take respiratory gas. their place. Autonomic nervous system The body system Appeal A request for an appellate court to change the that maintains the involuntary, yet essential, life- decision issued by a trial level court. preserving functions such as digestion. 794 Glossary Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. AV block An interruption of AV conduction that can be Beta1 adrenergic receptors Sympathetic indicative of disease or ischemia at the level of the neuroreceptors that cause the muscle of the heart, AV node. the myocardium, to beat harder and stimulate the AVPU A technique used to report the patient’s general heart to beat faster. Beta1 adrenergic receptors level of consciousness. A stands for alert, V stands for are also found in the kidneys where they cause the responsive to voice, P stands for responsive to pain, secretion of renin. and U stands for unresponsive. Beta2 adrenergic receptors Sympathetic Axis The major direction, or vector, of the energy of neuroreceptors that act upon the smooth muscles depolarization in the heart. found in the bronchial walls, the level of the terminal Axis deviation Any situation in which the heart’s axis bronchioles, and cause bronchodilation. is not normal. Beta-blockers Medicines that block the sympathetic Bachmann’s Bundle A special pathway the SA node nervous system action at the Beta receptors. uses to communicate with the left atrium. Beta-selective Drugs that preferentially targets either Bacterial contamination Infection of blood products Beta1 or Beta2 receptors. often due to contamination during the blood Bevel An angled surface of a needle point designed to collection process, which can lead to septic patients quickly pierce the skin with a minimum of pain. following transfusions. Bigeminy Condition in which an ectopic complex Balanced anesthesia Process of using a combination occurs at every other complex. of anesthetic agents—some inhaled and some injected Bilateral Relating to both the left and right sides. intravenously—to minimize the side effects that occur Bioavailability The difference between the amount of with using only one particular anesthetic agent. a drug administered and the amount that is bound and Barotrauma Physical damage to tissues, or an injury unavailable for use. For example, imagine an aspirin caused by an imbalance between pressures in the pill with 325 mg of active ingredient is swallowed, and environment and those within the body. then after various factors come into play, only 150 mg Barrel The shaft of a syringe. is free and unbound in the blood plasma. Thus, less Base Atoms that lack a proton and therefore want than 50% of the medication is bioavailable. to accept protons from an acid in order to become Bioethics A form of applied ethics—that is, ethics electrically balanced; a substance with a pH value applied to the medical situation—which creates a set greater than 7. of guiding principles for the medical practitioner. Baseline vital signs An initial set of vital signs taken Biological death Death associated with irreversibility, from the patient against which all subsequent vital meaning that any efforts to prolong life would be signs are compared to check for changes. futile. Basic life support (BLS) The early assistance given Biotransformation A detoxifi cation process in the to patients in the fi eld, such as CPR, oxygen, and body that simply transforms a drug—by oxidation, suction. hydrolysis, or reduction—into a water-soluble Battery An intentional tort involving unwanted compound which can be excreted in the urine. touching. Bipolar leads Use of two electrodes—one negative Behavioral emergency Abnormal or bizarre behavior and one positive—to measure the electrical potential that may include violence or threats of violence. between the leads’ electrodes. Benefi cence A belief that the physician’s actions are Blastocyst A hollow, fl uid-fi lled ball formed by the acts of mercy and charity, a good act performed for zygote. The cells inside of the blastocyst will form the people at a time of need. human, whereas the cells on the outside will form a Benign Something that will not harm or threaten protective covering that eventually develops into the health. placenta. Benzodiazepines Medicines that help relieve Blebs A small blister created when injecting nervousness, tension, and other symptoms by medication, which is about the size of a mosquito slowing the central nervous system. These drugs bite; a change in the cell wall membrane. are short acting, share the characteristics of the Blind insertion airway device (BIAD) An airway other benzodiazepines, and have been studied in the management tool that is placed blindly and provides prehospital environment as a sole agent to facilitate an airway that is superior to face-mask ventilation, intubation. yet is not as protective as an endotracheal tube. Best practices Those actions which have led to the Blocking behaviors Self-protective behaviors that most desirable outcomes in the past. inhibit free dialogue with the Paramedic. Many Glossary 795 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. of these blocking behaviors are manifestations of Bronchodilation Widening of the airway’s lumen. psychological defense mechanisms. Bronchospasm Temporary narrowing of the smaller Blood bank Location where donated blood and air passages of the bronchi due to violent, involuntary blood products are evaluated and stored for future contraction of the smooth muscle of

the bronchi that transfusions. sometimes accompanies a respiratory infection. Blood-brain barrier Tight slit junctions in the Bronchus Either of the two primary divisions of the capillaries of the brain which prevent toxins and trachea that lead into the right or left lung; plural is chemicals, including drugs, from easily passing into bronchi. the brain. Buffered Actions taken to render an atom neutral (not Blood chemistry A study of the blood’s chemical to have an electrical charge). composition, such as its level of electrolytes. Bulimia Eating disorder characterized by binge-eating Blood pressure A measure of the pressure within the and then purging via laxatives or vomiting. blood vessels that make up the circulatory system. Bundle of His A wide, thick group of cardiac muscle The pressure will vary depending upon the type of fi bers that conducts an electrical impulse to the vessel and the phase of heart contraction. interventricular septum. Blood-typing Classifying blood as A, B, AB, or O based BURP technique A method to improve laryngoscopic on antibodies. view through backward, upward, and rightward Body armor A form of personal protective equipment pressure. used to protect the Paramedic from thrown objects or Butterfl y IV catheters A throwback to the days projectiles like bullets. of steel needles, in which short steel needles are Body habitus One’s physique or body build. embedded into a plastic anchor device that has wings, Body language The transmission of a message by like a butterfl y. nonverbal visual cues. Experts suggest that 70% of any Calibration Process used to assess the accuracy of the spoken message is conveyed by body language. ECG monitor, in which the Paramedic compares the Body substance isolation Protection worn to keep a ECG machine’s operation against standard settings. patient’s body fl uids from coming in contact with the Capacity The mental ability to understand what one is Paramedic, such as latex gloves. being told. Bolus A concentrated volume of fl uid infused rapidly Capillary refi ll A measure of the patient’s ability to over several seconds or minutes. perfuse the extremities with oxygenated blood. Borrowed servant doctrine Situation in which the Capnography The process of tracking the carbon Paramedic in charge of an emergency is responsible dioxide in a patient’s exhaled breath, which enables for the actions of those Paramedics working in a Paramedics to objectively evaluate a patient’s subordinate role. ventilatory status. Bounce A radio wave phenomenon that occurs Capnometry The determination of the end-tidal whenever a short wave strikes a refl ective surface and partial pressure of carbon dioxide. is redirected in another direction. Capsule Medicinal powder placed within a gelatin Bradycardia A heart rate that is under 60 beats per casing that generally makes it easy to swallow and minute for an adult or below the lower limit of normal keeps it from easily dissolving in the water-based for a child. saliva of the mouth. Bradykinesia Extremely slow movement. Cardiac action potential The electrochemical Brain dead A state in which an electroencephalogram activity of the heart’s individual cells. shows zero brain activity, indicating brain death. Cardiac cycle A single contraction (one heartbeat), Breach of duty Situation in which a Paramedic fails during which blood fl ows through all four chambers to perform patient care in conformance with the of the heart. This contraction includes an entire standard of care. sequence of events from atrial fi lling through Breakthrough seizure An unexpected epileptic ventricular fi lling and ejection. seizure in a person who has had good seizure control, Cardiac monitor A device that shows the electrical which occurs when the drug level in the plasma drops and pressure waveforms of the cardiovascular system; below the therapeutic level. the ECG oscilloscope. Bronchial sounds Lung sounds auscultated over Cardiac output The volume of blood pumped out of the larger airways that are louder and sound like air the left ventricle with each contraction. rushing through a hollow tube. Cardiac skeleton A fi brous matrix to which the Bronchoconstriction Narrowing of the airway’s lumen. muscles, valves, and rings of the myocardium 796 Glossary Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. are attached and that separates the atria from Channel crowding Situation in which several agencies the ventricles. share the same radio frequencies. Cardiogenic shock Problems with the heart that lead Chart audit A system of quality review performed to its failure to pump. retrospectively in which the Paramedics reviews the Cardioselective Beta-selective drugs that only affect chart against care standards. the heart. CHEATED A mnemonic for an EMS-specifi c, user- Carina Level of the 5th thoracic vertebrae; an friendly documentation method highlighting chief anatomical part, ridge, or process. concern/complaint, history, examination, assessment, Carotid bruit A whooshing sound heard in a carotid treatment, evaluation, and disposition. artery that has plaque buildup on the artery walls. Chemical hiatus Situation in which the drug level in Carotid pulse A measure of the beats produced by the body drops below the therapeutic level before the blood fl ow taken in the anterior neck. infusion has assumed dominance. If left untreated, a Carrier squelch A type of squelch control that potentially life-threatening return ventricular ectopy eliminates background static during pauses in a radio could occur. transmission, essentially muting the radio between Chemical name A description of a drug according to its transmissions and thereby improving the message’s elemental chemical makeup and molecular structure. overall quality. Chemotactic factors Chemical messengers released Case law Law established by previous judicial by mast cells that attract specifi c leukocytes (white decisions. blood cells) to the injury site. Case report An example of a descriptive study Chemotherapy Use of drugs to combat infections and Paramedics use to report interesting or unique cases, diseases, most notably cancer. which allow other Paramedics to gain insight into a Chest leads Leads in which the exploring electrode is problem. placed on the chest and the other is connected to one Case-control study An observational study method in or more limbs. which the Paramedic compares cases—those patients Chevron Method for securing a catheter hub that with the disease—to controls—those patients without involves slipping the inverted tape, sticky side up, the disease—and then examines the procedures under the hub until it adheres to the hub, then performed on both to see if there was an association crossing it over the hub. between outcomes. Chief concern or complaint (CC) The main reason Catecholamines A classifi cation of very potent for which the patient is seeking medical care. adrenergic agonists that cause a direct response from Cholinergic transmission The transmission of a the adrenergic receptor. nervous system signal using acetylcholine as the Cell An area that a mobile radio transmission tower neurotransmitter at the motor endplate. services for cell phone calls. Chordae tendinae Strong cords of connective tissue Cell-mediated immunity Immunity that results from that connect the mitral valve to the papillary muscle the activity of T lymphocytes of the heart’s left ventricle. Cellular telephones Low-powered wireless Choreography The ability to organize a team’s efforts transmitters (radios) that work within close proximity in order to deliver appropriate interventions in a to a radio tower. timely manner. Cellulitis A skin infection. Chromosomes A double helix of DNA that carries Cell wall membrane A porous semipermeable dual genetic information. layer lipid–protein matrix that makes up the outside of Chronotropy To make the heart beat faster. a cell. Circumfl ex (Cx) A minor branch of the left coronary Celsius scale A method of measuring temperature artery that bends around to the left side of the heart and based on a system of 10 in which water freezes at 0°C provides blood to the lateral wall of the left ventricle. and water boils at 100°C. Civil law The legal system designed to handle cases Central nervous system depressants Drugs that not of a criminal nature, often involving business produce a state of reduced central nervous system transactions, such as contracts, torts, estates, trusts, activity. wills, real estate matters, commercial matters, and Central venous pressure (CVP) A measurement used grievances against the government. to assess a patient’s hemodynamic status. Clarifi cation Communication technique in which a Cerebellum The portion of the brain responsible for Paramedic asks the patient to restate the message in coordination of muscles and balance. other words. Glossary 797 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Climacteric An age-related decrease in sex hormone Cognitive restructuring Action taken to reframe the production that occurs in both men and women. brain’s interpretation of a stimulus so that it is non- Clinical death The absence of vital signs. Clinical threatening. death is characterized by unresponsiveness to loud Cohort study An observational study method that verbal and painful stimuli, absence of breathing, and examines patients who have been exposed to a an absence of a central pulse. treatment and compares them to a group that was Clinical decision making The process of systematic not exposed to the same treatment. The patients are analysis and critical thinking the Paramedic uses to followed to determine outcomes. make clinical decisions that will be incorporated into Cold maceration Process of letting medicinal herbs a patient’s treatment plan. steep in cold water. Clinical trial Experimental medical research process Colloid Blood substitutes that contain proteins and in which subjects are assigned at random to either are capable of both pulling fl uids from within the the treatment group or to the non-treatment interstitial space into the circulation (to help augment group (i.e., those receiving standard care [control the circulating volume) and remaining within the group]). bloodstream for a prolonged period of time (to help Clock method Procedure used to determine the maintain the circulating volume). infusion rate in which the Paramedic mentally Colorimetric device Encapsulated pieces of litmus visualizes a clock with a sweep hand pointing out paper over which an exhaled breath fl ows. When the drug infusion rate. When the sweep hand is at carbon dioxide is in the presence of water, it forms the 15 second point, it represents 1 milligram of carbonic acid; the pH sensitive litmus paper in the drug at 15 drops per minute or 15 milliliters an hour. colorimetric device detects this acid and changes color. When the sweep hand is at the 30 second position, Combining forms Creating a word by placing two it represents 2 milligrams of the drug infusing at or more roots together, separated by a vowel, to 30 drops per minute, and so forth. explain a complex process. For example, the term Clonic Repetitive muscle contractions during a “cardiomyopathy”, meaning disease of the muscle of convulsion. the heart, is made up of “cardia-” (meaning heart), Closed-ended questions Questions that generally “my” (meaning muscle), and “patho” (meaning start with words like “do,” “is,” or “are” and require disease), with the letter “O” separating the roots the answer to be a short, direct reply—usually just “cardia”, “my”, and “patho.” “yes” or “no.” Closed-ended questions are used when Command presence The ability to present oneself as specifi c information is needed quickly. the person of authority. Clot tubes A red top blood sample tube that contains Commercial ambulance services For-profi t no additives or preservatives to prevent blood EMS services that provide interfacility medical clotting. transportation as well as emergency medical services Coagulation The thickening process through which the to patients. Many of these commercial ambulance blood makes clots. services originated from the funeral homes that Coagulation cascade The process the body uses to previously provided the service. manufacture fi brin and fi brinogen. Communications Act of 1934 A resolution which Coagulation factors Proteins which act to attract states that the President of the United

States has platelets to each other to build platelet plugs. control over all government radios and that the Additionally, coagulation factors are key to the Federal Communications Commission (FCC) has control production of fi brin and fi brinogen, two materials over the civilian use of radios. that serve to solidify and stabilize the platelet plug, Communications specialists (COMSPEC) Enhanced making it impermeable to liquid. 9-1-1 staff that dispatch emergency responders to Coagulative necrosis Condition in which muscle people who are unable to speak or who have lapsed cells die, such as in myocardial infarction, the into unconsciousness. skeleton of the cell remains, and the tissue remains Community-based EMS Volunteer (nonprofi t) EMS firm. squads that operate independently of local fi re Coded (or tone) squelch Sometimes called private departments or hospitals. line, a type of squelch control that permits the radio Competency assurance The necessity of the to receive only the intended signal by eliminating Paramedic not only to maintain minimal skills and an reception of nearby broadcast messages and only adequate knowledge base, but to continue to remain accepting signals with the correct code. current with updates to EMS. 798 Glossary Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Complementary medicine See Alternative medicine. Continuous quality improvement (CQI) An ongoing Complete blood count (CBC) The quantity of each process of review and re-engineering, in order trying type of blood cell in a given sample of blood, often to refi ne a process and improve its delivery. including the amount of hemoglobin, the hematocrit, Contractility The cardiac muscle fi bers’ ability to and the proportions of various white cells. shorten or contract. Complete heart block Obstruction of electrical Contributory negligence A legal assertion that an signals through the AV node or at the bundle of His, action, although not directly causing an injury or in which case pacemakers lower in the heart at the problem, nonetheless made it worse. level of the bundle of His, bundle branches, or even Cormack-Lehane grading system A quantitative the ventricular myocardium will take over as the measure system that grades the view of the glottic pacemaker. opening by how much is occluded by the tongue— Comprehensive Drug Abuse Prevention and Grade I is a clear view of the entire glottic opening Control Act of 1970 (Controlled Substance whereas IV is visualization of the tongue or soft palate Act) A law that expanded the Drug Enforcement only. Proper patient position and external laryngeal Administration’s authority to include schedules of manipulation can improve the view by one to two grades. potentially dangerous and addictive drugs that had Coronary artery disease (CAD) The series of events special restrictions. that leads up to and includes myocardial infarction. Concealment Any object that blocks the pursuer’s Coronary circulation A special set of arteries and vision of the Paramedic, although it does not offer veins that supplies blood to the muscles of the heart. physical protection. Cortisol A glucocorticoid hormone that stimulates the Concentration gradient The difference in production of glucogen from amino acids and fatty concentration between two solutions in different acids contained in lipids. areas (i.e., on two sides of a membrane). When a Cost–benefi t ratio A classic economic analysis that concentration gradient exists, the higher concentration asks the question of whether it is advantageous will diffuse across the membrane to the lower- (i.e., cost-effective) to take a particular action or concentration solution until a balance is reached. make a change in a procedure. Concept formation The inductive logic process Costal margin The lower edge of the chest (thorax) of forming ideas about what is causing a patient’s formed by the bottom edge of the rib cage. condition based on the patient’s history and the Costovertebral angle Area located over the lower Paramedic’s knowledge base. ribs just medial to the posterior axillary line. Conduction system Specialized cardiac cells designed Countermeasures Steps that could be effective in to carry on the heart’s electrical rhythm. reducing injury. Conductivity The ability of an electrical stimulus to be Couplets Situation in which two ectopic complexes transmitted from cell to cell. occur together. Congestive heart failure (CHF) The heart’s inability Cover Any object that cannot be penetrated by a to pump strongly enough to completely meet the projectile, from bullets to frying pans. Examples of body’s needs for oxygen and nutrients. cover include telephone poles and even fi re hydrants. Conjunctiva The mucous membrane that lines the Crenate Dehydration and collapse of a cell. inner surface of the eyelids. Crepitus Crackling or popping sounds under the skin or Conscious sedation The fi rst stage of anesthesia near joints. where the patient does not feel pain but is awake Cricoid pressure Also called the Sellick’s maneuver, enough to maintain protective airway refl exes. a procedure that involves identifying the cricoid Constitutional examination An evaluation that ring and gently applying approximately 10 pounds of assesses the patient’s general appearance. pressure in a posterior direction throughout airway Constitutional signs/symptoms General nonspecifi c management; from the onset of ventilation until fi ndings, such as fevers, unexplained weight loss, night completion of intubation. sweats, chills, headaches, nausea, and vomiting, that Criminal law Laws dealing with violations of a person’s are often common to all sick patients. duties to the community and for which the written law Contiguous leads Situation in which two or more requires the person to provide satisfaction. leads look at the same wall of the left ventricle. Critical incident response team (CIRT) Individuals Continuous infusion A volume of fl uid evenly called in during an acute stress situation to meet administered over the course of a period of time with the affected personnel, typically front-line (i.e., an hour). responders. Glossary 799 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Critical incident stress debriefi ng (CISD) An Decode To interpret and understand a message. intervention to defuse stressors in an acute stress Decubitus ulcers Also known as pressure ulcers, tender situation, such as a line-of-duty death, serious injury or infl amed patches that develop when skin covering a of a coworker while on-the-job, and post-event weight-bearing part of the body is squeezed between suicide of a fellow responder. bone and another body part, or a bed, chair, splint, or Cross-match Comparing a donor’s blood to a patient’s other hard object, creating pressure or friction. blood to determine compatibility of antibodies and Deep tendon refl exes (DTRs) Involuntary muscle type. contraction in the muscle associated with a tendon. Cross-sectional survey A snapshot of a certain Defasciculating dose A small dose of a non- aspect of a population at a given moment in time that depolarizing paralytic which, when administered the researcher is interested in, obtained by means of before administering a certain drug, prevents the observation. fasciculations associated with that drug. Crowning Part of the childbirth process in which the Defensive medicine The practice of a Paramedic infant’s head begins the passage into the birth canal, performing a wide variety of random tests to limit indicating delivery will occur within several minutes. liability or criticism from the medical director, rather Cryoprecipitate The protein portion of plasma made than performing just those tests that benefi t the up of concentrated clotting factors. patient. Crystalloids Electrolyte-containing fl uids Paramedics Defusing An immediate intervention intended to use during trauma resuscitation that, when avert acute stress reactions among the emergency dehydrated, create crystals. responders. Cultural competence A Paramedic’s ability to Degranulate The process of breaking down or losing function effectively within the diverse populations granules. that she serves. Delirium A sudden change in mental function, usually Culture The culmination of life experiences in a associated with reversible metabolic derangements locality or region that affects the way a person thinks (e.g., hypoxia, or the toxic effects of medications). and behaves. Deltoid An intramuscular injection site in the muscle Cyanosis A bluish hue that develops when the patient that overlays the shoulder and extends downward develops a decreased oxygen level in the blood. toward the elbow, forming an inverted triangle in the Cytopathic Manifestations of disease at the cellular level. process. Cytoplasm A fl uid mixture inside a cell, primarily Demobilization An opportunity to mitigate the effects made up of water and organelles, which has a specifi c of the acute stressors and to decrease the incidence cellular function(s). of acute traumatic stress reactions. Dangerous instruments Any object that could be Denature To break down a protein’s complex folded used, under the right circumstances, to produce structure. serious injury or even death, such as a broken bottle Deontology Duty-based ethics in which the decision or box cutter. as to whether an action is right or wrong is based on Data and Safety Monitoring Board (DSMB) A principles and not upon the consequences. group of individuals who are not directly involved in Depolarization A cascade of ionic changes at a cell a research study but who can nonetheless make an wall that occurs as electrolytes transfer across the cell objective decision about the research based on the in an attempt to balance (neutralize) the charge. merits of the data. Depolarizing neuromuscular blocker One of the Data dredging Sometimes called data mining, it two major classes of neuromuscular blockers; binds to means conducting research by searching through a the acetylcholine receptor and causes the muscle to database without a predefi ned scientifi c question in depolarize or contract. mind (i.e., without a predefi ned hypothesis). Deposition Out-of-court testimony made under oath and Dead airtime A period in which no radio transmissions recorded by an authorized offi cer for later use in court. are made on a particular channel. Descriptive analysis Based on the Marriott method of Deadly weapons Objects that are, by design, analysis, a way to gather information for a thorough intended to infl ict death or disability (e.g., a gun or ECG interpretation consisting of review of the rhythm, a knife). rate, width of the QRS complex, and atrial activity. Decoction Process of bringing water to a boil then Descriptive study Documentation that simply states steeping medicinal herbs in the water (like one would that a condition or situation exists without trying to steep a teabag), then drinking the resulting solution. offer an explanation. 800 Glossary Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Detailed physical examination A more thorough Distracting injury Situation in which a pain (often evaluation given to low-priority patients with whom dull visceral pain) is overshadowed by another more the Paramedic has more time. intense pain from another injury; for example, a Developmental milestones The skills and abilities fractured femur taking attention away from chest a child achieves at certain ages in his or her life, pain. measured against the norms of other children. Distress A negative response to stimuli that overcomes Dextrocardia Condition in which the heart and lungs the body’s innate defenses and serves as the body’s in a body are opposite their normal position while the maladaptive reaction to stress. abdominal organs are in their usual position. Distributive shock The third category of the Diagnosis Identifi cation of a disease or disorder based Hinshaw–Cox shock classifi cation, which is descriptive on available symptoms and testing. of the problem of poor blood distribution. Distributive Diagnosis-related groups (DRG) Groups of patient shock includes

shock caused by the widespread populations with the same or similar diagnosis, who vasodilatation seen with severe infections and during may benefi t from similar treatments. anaphylactic reactions, to name a few causes. Diaphoretic To be profusely sweaty. Diuretics Medications that cause the increased loss of Diaphragm A large, thin, dome-shaped muscle that fl uid and salts from the body. divides the abdomen from the thorax. Divine command ethics Extrinsic ethics based Diastolic blood pressure The minimum blood upon a higher authority, such as the Bible’s Ten pressure measured during diastole when the heart Commandments or Buddha’s Four Noble Truths and relaxes and fi lls. Eight Paths to Righteousness, in which that higher Digital intubation An endotracheal intubation authority has predetermined what qualities a virtuous technique that uses the Paramedic’s hand to identify person would have and calls upon the person to laryngeal structures and to guide tube placement. display those virtues through correct action. Diminished autonomy Standard that states any Dominance A condition of superiority, as in when person who is mentally incapable of making an the actions of one bodily function are faster than or informed decision (e.g., by virtue of age or infi rmity) overpower the actions of another. cannot willingly consent to participate in research. Do-Not-Resuscitate (DNR) order Sometimes called Diphasic A wave that begins as a positive defl ection a Do-Not-Attempt-Resuscitation (DNAR) order, a then becomes a negative wave or vice versa; having directive from the patient that artifi cial means of life two phases. support should not be used, generally in cases when a Diplomacy To calmly and thoughtfully resolve issues condition is terminal and artifi cial life support will just without angering the parties in the dispute. delay the inevitable. Direct questioning An interviewing technique DOPE A mnemonic Paramedics use to help remember in which a Paramedic asks simple, unambiguous the causes of problem intubations. The D in dope questions of the affected party about the situation at stands for displaced endotracheal tube; the O stands hand. for obstructions of the endotracheal tube, such Disclosure An open dialogue between patient and as a mucous plug; the P suggests the possibility of provider in which the provider tells the patient about a pneumothorax; and the last letter, E, indicates the procedure, including its attendant risks, and equipment failure. recommends the procedure. Dormant A state of biological rest a disease may stay Disease An abnormal change in the function of cells, in until favorable conditions exist for it to reanimate. tissues, or organs. An example of each is cancer in Dorsalis pedis (DP) pulse A measure of the beat cells, emphysema in tissues, and acute myocardial created by blood fl ow measured over the dorsum of infarction in organs. the foot. Disorder A physiological deviation from a normal Dorsifl ex The ability to raise toes above the horizontal homeostasis. toward the tibia. Disseminated intravascular coagulation (DIC) Dorsogluteal (DG) The most common intramuscular A condition in which, after initial blood clotting injection site, located in the gluteus medius. factors are partially consumed by massive coagulation Dose The amount of drug needed to produce the throughout the body, the remaining clotting factors desired effect. are insuffi cient to protect the body. Double-blinded randomized clinical trial (RCT) Distention An abnormal expansion, such as in a vein or A prospective scientifi c study that controls known the abdomen. and unknown variables, leaving only one variable to Glossary 801 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. be manipulated. Subjects are then chosen at random information about trends and rates of disease within to be included in either the experimental treatment a population, often cited as X number of cases of Y group or in the control group. disease per 1,000 or per 100,000 of Z population. Double-blind study A research study in which both Ectopic To occur in an abnormal or atypical position. the researcher and the participants are unaware of Ectopic beats Aberrant cardiac beats resulting from which group the subject is in. abnormal automaticity. Downregulation A decrease in the number of cell Ectopic focus Any complex that occurs outside of the receptors in a cell due to changes in hormone levels. sinus of the heart’s cavity. Dress-up philosophy Technique in which Paramedics ED50 The dose of a drug that effectively creates the add barrier devices for protection as the situation therapeutic effect in a majority of patients. warrants. Edema A dramatic fl uid buildup in the body’s tissues. Drug Any material which, when injected, ingested, Edentulous A state of having no teeth. inhaled, or absorbed into the body, is used for Effi cacy The power to produce an effect; the ability of the diagnosis, treatment, or cure of a disease or a drug to realize its full intended therapeutic effect. condition. Ejection fraction The percentage of blood pushed and Drug decline The idea that while a drug moves squeezed out of the heart, typically 60% to 75% of the through the body various forces and organs are end diastolic volume. weakening it, reducing its effectiveness. Elastic gum bougie A device made entirely of wound Drug reservoir A type of drug depot in the body, gum rubber, with a hard, smooth, and round plastic created when drugs bind to certain substances, that tip, that resembles a very long stylet. The device is stores the drug until it is needed. The effect of a drug directed through the vocal cords and into the trachea reservoir is to prolong the drug’s action within the body. to serve as a guide for an endotracheal tube. Dry powder inhalers (DPI) Respiratory device that Electrical alternans Situation in which every other uses a solid drug pulverized into micro-fi ne particles ECG complex has alternating amplitude (i.e., the one for inhalation. QRS complex is smaller when compared to the next). Duplex A radio that uses two frequencies—one to Electrical storm Multiple recurrent episodes of transmit and one to receive—so that an operator can ventricular fi brillation. talk and listen at the same time, permitting more Electrocardiogram A device used to monitor cardiac rapid communications. rhythm. Duration The length of a QRS complex wave. Electromagnetic interference (EMI) Disruptions of Duty to act An element of a tort that implies a an ECG signal caused by the fl ow of electricity through Paramedic must act whenever called upon to perform an electric device, such as a radio, cellular telephone, patient care (i.e., the Paramedic is “on duty”). or television, which creates an electromagnetic fi eld. Dyskinesia Lack of ability to control body movements. Electromyographic signal (EMG) An electrical Dysplasia Situation in which there are too many current recorded by the ECG any time a muscle new, or immature, cells being produced that are not contracts, appearing as narrow rapid spikes on the functional. ECG monitor. Dysrhythmias An abnormality of the electrical activity Electroporation The effect of electrical current in the heart. passing through the tissue. Ecchymosis Blood from ruptured vessels moving into Elixir A sweetened tincture used for medicinal purposes. other tissues; bruising. Emancipated minors A special class of youths who ECG interpretation A systematic approach used to are below the age of majority but are permitted to rapidly and accurately analyze an ECG rhythm strip. give informed consent, provided they are capable of ECG rhythm strip A printed hard copy from an understanding the consequences of their decisions and ECG machine of at least one lead that shows the that they are not impaired by alcohol or drugs. These ECG complexes over a long period of time allowing include married persons, single parents, the military, Paramedics to analyze the rhythm. and youth living on their own. Echo technique Communication method in which the Embryo An unborn child at any stage of development physician gives an order and the Paramedic, in order between conception and birth. to ensure it’s been interpreted correctly, repeats the Emergency doctrine Policy invoked when family order back to the physician exactly as received. members or guardians are not present that states Ecological study Sometimes called a correlational if a parent was present the parent would want the study, this type of research design serves to provide child treated and transported to the hospital. The 802 Glossary Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. emergency doctrine is usually invoked only in cases of Emulsions Finely pulverized particles placed into oils, life- or limb-threatening emergencies. such as cod liver oil. Emergency exception A situation in which a care Endocardium A single-layer thick sheet of epithelial provider performs a procedure without fully explaining cells that act as a lining in the heart; the heart’s it to the patient because the delay created by a lengthy innermost layer. explanation might compromise the patient’s health. Endocrine shock A fi fth classifi cation of shock, Emergency medical dispatch (EMD) A dispatch which recognizes the importance of hormones in algorithm in which the communications specialist maintaining homeostasis. The classic endocrine shock interrogates the caller, gives prearrival instructions, is hypoglycemic shock. and uses preset criteria to make a response Endogenous Originating within the body. determination before dispatching the appropriate EMS Endorphins Neuromodulators that reduce the responder units. sensation of pain and affect emotions by attaching to Emergency medical responder (EMR) An EMS opiate receptors on the neuron, which in turn inhibit provider who is expected to render life-saving care neural activity. with minimal equipment; for example, a police offi cer Endotoxins Poisons produced by bacteria during an or fi re fi ghter providing rapid response. infection that stimulate chemical mediators to affect Emergency Medical Services (EMS) The fi eld the hypothalamus. of medicine that involves transporting the sick or Endotracheal tube The basic tool of endotracheal wounded to medical care and providing treatment to intubation which provides a conduit for oxygenation patients prior to their arrival at the hospital. and ventilation between the patient’s lungs and the Emergency Medical Technician-Ambulance A ventilator (person or machine). national standard curriculum established in 1969 for End-tidal carbon dioxide (ETCO2) A standard the training of ambulance drivers/attendants in new method of measurement and monitoring carbon skills and life-saving techniques. dioxide levels used for both confi rming endotracheal Emergency Medical Technician (EMT)–Basic Part tube placement and monitoring patient status, of a team that responds to the emergency scene, ventilation, and continuing tube placement. typically aboard an ambulance, and is trained to Enhanced excitability The ability to respond to a provide initial care on scene as well as medical care much weaker stimulus. to the patient while in transit to the hospital. Enteral Administration of drugs through the Emergency vehicle operator (EVO) Any individual gastrointestinal tract, either through pills taken orally who operates a vehicle en route to a response call. or through suppositories. Emergent An assessment classifi cation in which the Enteric coating A protective coating on a tablet that patient’s condition unexpectedly developed and is in permits the tablet to travel, unaltered, through the need of immediate medical attention. stomach and into the intestine for absorption. Empathy An emotional understanding of the patient’s Environmental risk Modifi able risk factors that are a feelings; to be able to understand what it is like to function of one’s lifestyle or occupational choice, such walk in the other person’s shoes. as farmers developing respiratory issues from their Empiric therapy Treatment based on initial exposure to dust. observations obtained during the primary assessment. Epicardium The heart’s outermost part; a part of the EMS Act of 1973 Federal legislation that delineated pericardium that is closely adherent to the heart. the 15 aspects of an EMS system that needed Epidemiology The study of the

causes, distribution, improvement including education (both public as well and control of disease in populations. as provider), improved communications (including Epiglottis A “U” shaped structure in the upper airway public access), and system evaluation, but offered attached to the anterior pharynx between the base little money to help make those improvements. of the tongue and the larynx that protects the lower EMS Agenda for the Future Overall framework which airway from foreign body aspiration. suggests that EMS will be more intimately intertwined Epilepsy A neurological disorder characterized by with public health, as well as public safety, over time recurrent seizures that occur without known cause. and continue to evolve along with health care. Epistaxis Nosebleed. EMS Education Agenda for the Future The plans Equianalgesic Drug characteristic in which a dose that emerged from the 1996 meeting of over 30 EMS of a new medication formulation has the same organizations held with the intent of implementing the ability to produce analgesia as 10 milligrams educational portions of the EMS Agenda for the Future. of morphine. Glossary 803 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Equiphasic A fl atline pattern on an ECG machine that Event report Documentation following a mass casualty occurs if the differences in the fl ow of electricity incident that details the situation and conditions that result in a zero net difference in direction. occurred which led to the incident. Triage tags are Equity A concept of fairness or evenhandedness. To be attached to this report. accepted, any change must appear to be equitable to Evidence-based practice A research approach all parties concerned. based on observed experimental results, in hopes Erythema Abnormal redness of the skin caused by of making the results more reliable and valid than capillary congestion. peer reviews. Erythrocytes Red blood cells that transport oxygen Exacerbation Periodic episodes in which a chronic and carbon dioxide through the blood. disease returns, or fl ares up. Escape mechanism A form of backup pacemaker Excitability The ability to respond to a stimulus. in the heart that will continue to prompt Excited delirium A physical state a restrained contractions (at a slower rate) if the SA node stops patient may reach if agitated and combative in which sending impulses. he becomes tachycardic, hypertensive, and has Esophageal intubation detection devices (EDD) hyperpyrexia. Devices used to confi rm endotracheal tube placement. Exercise A series of physical activities, both aerobic Two major styles of these devices exist: self-infl ating (e.g., walking or jogging) and strength training, which bulbs and syringe style aspirators. is considered optimal to perform for maintaining Esophageal-tracheal Combitube (ETC) A rescue health. device placed into the esophagus that allows tracheal Exhaustion The fi nal, recovery stage of the general placement. The double-lumen design allows for adaptation syndrome, which occurs when the body’s endotracheal as well as esophageal intubation. response is insuffi cient to meet the challenge of the Ethical relativism When a majority of Paramedics stressor. agree to a specifi c conduct or course of action, Exogenous Originating outside of the body. determining that it does more good than harm, which Exotoxins Proteins produced by bacteria that are suggests the act is ethical. released into the interstitial fl uid. They are then Ethics From the Greek “ethos” meaning character, a absorbed, because they are highly soluble, into system of guiding principles that govern a person’s surrounding cells. conduct. Expanded scope of practice Assigning additional Ethics committee A group that can help individuals, duties and responsibilities to Paramedics beyond the including Paramedics, deal with common ethical scope of practice to provide health care where scarce concerns. healthcare resources exist. Ethnocentrism A view that one’s own cultural Exposure Situation in which blood or bodily fl uids from practices and customs are superior. a patient are spilled, splashed, or dripped onto or Etiology The origin of a disease. injected into a Paramedic. Etomidate A sedative that functions primarily as a Exposure report A special incident report completed hypnotic, although it also is an excellent amnestic. after an exposure that details the circumstances that Eustress A positive, manageable form of stress from resulted in the Paramedic being exposed, in hopes daily activities. that a future exposure will not occur in the same Eutectic mixture of local anesthetics (EMLA) manner. A cream that helps to reduce the pain of needle Expressed consent During an emergency situation, insertion, consisting of lidocaine 2.5% and an assumption that if a patient does not object to prilocaine 2.5%. receiving care, consent for the procedure has been Evaluation and Management Documentation given. Guidelines Standardized histories that permit External laryngeal manipulation A technique the Paramedic to identify diseases, disorders, and used to improve visualization of the glottic syndromes, vis-á-vis, through symptom pattern opening in which the Paramedic performs direct recognition, and document the medical necessity of laryngoscopy with his left hand while manipulating the therapeutic services provided to the patient. the larynx with his right hand. Once he has Event monitor A credit-card sized device patients an improved view of the glottic opening, the may use to record abnormal ECG activity that occurs Paramedic has an assistant take over the external very irregularly (as in days or weeks apart). When the laryngeal manipulation, holding the larynx patient senses the abnormal activity, the monitor is absolutely still. placed on the chest for a preset period of time. Extracellular water The water that is outside of cells. 804 Glossary Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Extrinsic trigger A stimulus prompting an airway Fetal alcohol syndrome Umbrella term covering a spasm that originates outside the body, such as variety of birth defects caused by a mother drinking pollen, dust, and mold. during pregnancy. Exudate A collection of white blood cells and fl uids; Fetal hydantoin syndrome (FHS) Birth defects whitish discharge. such as cleft lip, cleft palate, and congenital heart Facilitation Interviewing technique in which the anomalies seen in children born to mothers taking Paramedic nods his head in acknowledgement and says hydantoins during pregnancy. “Go on,” as well as tries to make eye contact, which Fibrin An elastic, insoluble, whitish protein produced may encourage the patient to continue talking about a by the action of thrombin on fi brinogen and forming subject. an interlacing fi brous network in the coagulation of Facsimile machine A device that, using digital blood. technology, can transmit a high-quality copy of Fibrinogen A protein in the blood plasma that is documentation from one location to another. essential for the coagulation of blood and is converted Fading Progressive weakening of a radio wave as it to fi brin by the action of thrombin in the presence of encounters more and more obstacles. ionized calcium. Fahrenheit scale A standard used to measure Fick principle The process of getting oxygen to the temperature based on freezing and boiling cells, which can be summed up in fi ve key concepts: temperatures of a water and salt solution. In this oxygenation, ventilation, respiration, circulation, and scale, water freezes at 32°F, water boils at 212°F, cellular respiration. and a person’s body temperature is 98.6°F. Fidelity The physician’s obligation, and therefore the Failure to thrive Situation in which a child does not Paramedic’s obligation, to keep any promises made to grow as expected, perhaps due to psychosocial or the patient. nutritional imbalances. Field A place to enter data on a chart or form. Fallout Situation that occurs in the airway whenever Field diagnosis See Paramedical diagnosis large particles carried in the air current settle out as Fight or fl ight The body’s instinctive response to a airfl ow velocity is lost. potential life threat, either to resist it or avoid it. This False imprisonment A restriction of movement or primitive stress response may have been critical to the a confi nement that abridges the patient’s right to survival of primeval man, but can be unhealthy today. freedom, such as by the use of restraints. Fire-based EMS Using the fi re service, with their FarMedic© An EMS course specifi cally directed to the combination of trained personnel, life-saving rural or farm emergency. equipment, emergency vehicles, and strategically Fasciculations Transient fi ne muscle contractions, located stations, as the platform for delivery of EMS; seen after administration of a depolarizing the predominant means of delivering EMS in the neuromuscular blocker. United States. Febrile non-hemolytic reaction An elevation of the First-due report A brief synopsis of the scene size-up patient’s temperature of 1°C from baseline within two obtained by the fi rst arriving responder. hours of the start of a transfusion which begins shortly First pass metabolism A chemical degradation of after the initiation of the transfusion or a new unit. a drug by the liver that markedly reduces the drug’s It is often secondary to minor antibodies present in bioavailability. the recipient’s blood that cause a mild reaction when Fixed-post staffi ng The method of resource allocation exposed to the donor’s blood. in which EMS is stationed in centrally located Federal Communications Commission (FCC) standing facilities, from which ambulances respond to The agency with rule-making and enforcement emergencies. responsibility for civilian radio frequencies. Fixed-wing aircraft A traditional airplane, rather than Feedback The mechanism by which the Paramedic can a helicopter, used by fl ight Paramedics to transport ensure the message sent was the message received patients. and decoded; that is, the message heard was the Flail segment Condition that develops when two message sent. or more adjacent ribs are fractured in two or more Fee for service A “pay as you go” approach to health places, which produces an unstable area of the chest care, with a certain amount of medical care provided that impedes normal respiration. gratis to the poor or uninsured. Flashback A return of blood that may be observed in Femoral pulse A count of the beats created by blood the tubing when an IV solution bag is lowered below the fl ow in the femoral artery that is measured at the level of the patient’s heart, which indicates that the IV patient’s groin. access remains patent. Glossary 805 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Flight Paramedic The most highly trained level of to determine which patients require immediate EMS provider; this individual transports critically ill transport. patients from emergency scenes or other facilities to Generation A span of time used to differentiate defi nitive care. advancements (e.g., the next generation of drugs). Fluori-methane A topical refrigerant, sometimes Generic name A simple name given to a drug, often called vapocoolant spray, that numbs the skin at the listed by the manufacturer in the United States injection site in as little as 15 seconds. Pharmacopeia (USP). Flush the line A procedure in which the Paramedic Genetic make-up Those physical characteristics that runs fl uid through an intravenous administration set make up a person, including appearance, disposition, to remove any air bubbles in order to prevent an air and so on. embolism. Genotype An individual’s genetic make-up. Focused/vectored physical examination (PE) Gestalt A decision-making process in which the A more detailed evaluation following the primary Paramedic comes to a conclusion not through a assessment in which the Paramedic looks for summation of symptoms but rather from patterns observations that the physician will most likely observed in

similar situations in past practice and request. experience. Also referred to as the Paramedic’s “gut Followership A willingness to follow a leader’s feel.” direction and to support the mission, putting aside Glottis The space between the vocal cords. personal ambitions. Glucagon An enzyme that breaks down glycogen into Food, Drug, and Cosmetic Act Law that prohibits individual glucose molecules. the sale of new drugs before they go through safety Glycogen A dual molecule in the liver and muscles that testing. stores any glucose which is not needed immediately by Foreseeable harm Risks that can reasonably be the body. expected as a result of a medical procedure. Glycolysis An aerobic process during which the body Frequency modulation (FM) When modulating an uses eight different enzymes to divide glucose and audio signal, changing the wave’s speed. create a chemical called pyruvate. Fresh frozen plasma Blood component formed by Glyconeogenesis The production of glucogen from removing the red blood cells and platelets from whole amino acids and fatty acids contained in lipids. blood. The remaining liquid component of the blood Glycoside Any of a group of organic compounds, is still rich in several of the clotting factors needed as occurring abundantly in plants, that yield a sugar and part of the coagulation system. one or more nonsugar substances on hydrolysis. Functional job description Tasks described in a job Good Samaritan statutes Laws that protect well- description that are needed to perform the functions meaning people who, although they have no duty to of the job, excluding rare or marginal job functions. provide care to an injured person, do so nonetheless. Functional syncytium A group of myocardial cells Governmental immunity Also called sovereign that act as a unit. immunity, a practice in which the government is Gain Enlargement in the size of the tracing shown on exempt from liability for torts committed by its the ECG monitor screen. employees except to the extent that it has consented Gait The way a patient walks. by statute to be sued. Gallop The combination of the normal and extra heart Gross negligence Intent to willfully, or with reckless sounds that occur with changes in ventricular fi lling. disregard for a patient, cause harm to a patient. This produces a galloping rhythm, similar to hearing a Ground wave High-frequency (HF) radio transmissions horse gallop. that are capable of being transmitted over the land. Garbage can diagnosis An imprecise and Guidelines General rules that provide the Paramedic overgeneralized fi eld diagnosis the Paramedic might with direction while also permitting use of her make that lends little direction to patient care. knowledge and experience to shape clinical decisions. Gene A sequence of nucleotides in DNA on a Whenever guidelines are in use, the Paramedic must chromosome that determines an individual’s physical be willing to discuss and defend the clinical decisions. characteristics. Gum Sometimes called resin, a complex sugar in plants, General adaptation syndrome The body’s a polysaccharide, that when moistened becomes a predictable pattern of response to stressors. gelatinous material. General impression A Paramedic’s overall evaluation Haddon matrix An easily understood concept map of of the patient, in which she assesses the patient’s injury causation and prevention. Using a model similar mental status, airway, breathing, and circulation, to the one used for disease, Haddon plotted the 806 Glossary Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. factors that cause injury across a horizontal X-axis and Hematocrit The volume of red blood cells in the blood the stages of an injury process along the Y-axis. The expressed as a percentage. result was an injury prevention matrix. Hematoma A mass of clotted blood that forms in a Half-life (t½) The point when the decline of the swelling as a result of a broken blood vessel. amount of a drug in the bloodstream due to Hematopoiesis The manufacturing process the body metabolism reaches 50%. uses to create the three main solid components Hands-off The process in which one mobile radio tower of blood: red blood cells, white blood cells, and switches the transmission to another tower so that platelets. there is no interruption in transmission. Hemicorporectomy Amputation at the waist. Hanger Hook-like device an IV bag is hung from. Hemocytoblast The generic stem cell from which all Hanging the bag Process of suspending an intravenous other blood cells (red, white, and platelets) develop. solution for delivery to the patient. Hemoglobin The molecule in red blood cells that Hard-wire Use of physical transmission lines for accepts oxygen in the lungs and carries it to the communication rather than radio waves, i.e., wireless. body’s tissues to allow cellular respiration. Hard wire monitoring Devices that feature electrodes Hemolysis The disintegration of red blood cells, running from the device to the patient, causing resulting in a release of hemoglobin. limited mobility for the patient. Hemostasis The stoppage of blood fl ow through a Harrison Act A law established in 1914 that made it blood vessel or body part. illegal to obtain “narcotics” (e.g., morphine) without Hemothorax Collection of blood in the pleural cavity a prescription. which can cause lung collapse. Head elevated laryngoscopic position (HELP) Heparin sulfate An anticoagulant released from A patient position that places the head in extension the endothelium of the walls of the arteries that along the atlanto-occipital joints, bringing the temporarily prevents blood clot formation in the pharyngeal, laryngeal, and oral axes into alignment narrowed coronary arteries. using an elevation pillow. It can also be used in Heparin well An intermittent infusion device fi lled patients who are unable to lay fl at (i.e., CHF with heparin to prevent clot formation in the device. patients or morbidly obese patients) or to help clear Hepatectomy The surgical removal of a portion of the secretions. liver. Healthcare proxy This person has a responsibility to Hepatojugular refl ux An elevation of venous pressure review the medical record, consult with healthcare visible in the jugular veins when fi rm pressure with providers, and give consent to either initiate or to the fl at hand over the liver. refuse care for the patient. Hermeneutics The Paramedic’s ability to put Health Insurance Portability and Accountability himself in the patient’s situation, with all of the Act (HIPAA) Federal legislation that has placed accompanying physical and cultural infl uences, in conditions upon all healthcare providers that protect order to understand the patient better. patient privacy during claims processing, data Hernia Openings in the muscle and tissue layers that analysis, utilization review, quality assurance, and allow the an organ to protrude through the opening practice management. into another cavity. Health maintenance organization (HMO) A Hertz A unit of frequency measured in cycles per managed care system that provides payments to second. healthcare providers at a negotiated annual per capita Hexaxial reference system An artifi cial construct rate. These rates are based on practice history of the created to help conceptualize the heart’s normal axis insured patients and helps to prevent fl uctuations in and to help determine if there is any axis deviation. payments, thus making expenses, costs, and budgets High-fl ow nasal cannula (HFNC) An advance in more predictable. nasal cannula technology in which, by humidifying and Heart failure Situation in which an impaired heart warming the oxygen and using membrane technology, cannot meet the body’s demands for perfusion. up to 40 LPM is comfortably delivered to the patient Heave To cause to swell or rise. When referring to through a nasal cannula. the heart, a heave indicates the heart is beating so High priority patients Patients with the most forcibly that the chest wall is felt to move by the serious, yet treatable, conditions. They are generally Paramedic assessing the patient. transported to the hospital immediately, with further Heel stick Puncturing an infant’s heel with a lancet assessment being performed en route. then drawing the blood off with a capillary tube to History of present illness (HPI) A chronological acquire a sample. description of the development of the patient’s Glossary 807 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. present illness, including symptoms the patient is Hyoid The only bone in the body that does not directly currently displaying, which may help the Paramedic articulate with another bone. Instead, it serves as a make a diagnosis. This can be determined by asking common point of attachment for a number of muscles when, where, why, and how type questions about the and ligaments that function in swallowing and airway problem. maintenance. History taking Medical questioning to determine the Hyperacute T wave An increase in the amplitude of disorder, syndrome, or condition affecting the patient T waves in the leads facing cellular damage. that resulted in the call for assistance. Hypercapnia Condition in which the partial pressure of Histoxic hypoxia The inability of the cells to accept or carbon dioxide dissolved in an arterial blood gas sample use oxygen, such as in cyanide poisoning. is greater than 45; increased carbon dioxide levels. Holter monitoring A continuous type of ECG monitor Hypercarbia Condition in which the amount of that records the ECG activity while the patient goes bicarbonate ions in an arterial blood gas sample is about his routine work and play activities, which is greater than 30. often used on patients with sporadic dysrhythmia Hyperlipidemia An abnormally high level of problems. triglycerides and cholesterol which, when Homeostasis The processes a body undertakes to try uncontrolled, can lead to atherosclerosis. to maintain a constant state of balance or equilibrium. Hyperoxia Condition in which partial pressure of Horizontal equity Injury prevention strategy in oxygen dissolved in the arterial blood gas sample is which standards are broadly applied to all individuals greater than 100. equally, such as the level of a legal blood alcohol Hyperplasia An abnormal increase in the number of content. cells due to frequent cell division/reproduction which Horizontal leadership A leadership style that causes the tissue or organ to increase in size. “fl attens the pyramid” so Paramedic leaders work Hyperpnea Deep breathing. toward linking, or networking, with the members of a Hyperrefl exive Refl exes that are signifi cantly more public safety team. Horizontal leadership emphasizes brisk than normal. an “out and back” line of communication instead of Hyperresonant Percussion notes that sound similar to an “up and down” line of communication and can be striking a drum, indicating an increased amount of air visualized more like a wagon wheel. in the chest. Hormones The chemical messengers that stimulate the Hypertension A systolic blood pressure that is above body’s organs and help to maintain the body’s internal the upper limit of normal. environment. Hyperthermia A condition that occurs if too much Hospice A concept of care focused on providing for the heat builds up in the body’s core; a body temperature physical, emotional, and spiritual needs of a terminal above 38°C (100.4°F). patient. Hypertonic Fluid that has less water and more salt Hospital-based EMS An EMS system design where a (electrolytes) than the solution on the other side of hospital provides EMS services in the form of a fl ycar a semipermeable membrane. Hypertonic fl uid on the or ambulance. other side of a semipermeable membrane will pull Hotline A telephone number dedicated to providing the fl uids into itself. caller with immediate assistance. Hypertrophy An increase in either the weight or Huber needle A beveled needle intended to pierce a functional capacity of a tissue or organ beyond what stopper without coring it, thereby preventing leakage is normal. of the contents within the catheter from leaking out Hyperventilation A deeper than normal respiration of the stopper when the needle is withdrawn. that may be caused

by respiratory distress, a Human dignity The right of every person to be treated metabolic condition, or drug overdose. respectfully, regardless of his or her station in life. Hypnotic state A sleep-like condition often induced by Human rights Rights based on a commonly desired a large dose of CNS depressants. human condition (i.e., freedom from want, freedom Hypocapnea Condition in which the partial pressure from pain, and freedom from suffering). Human rights of carbon dioxide dissolved in an arterial blood gas involve universally accepted standards of justice. sample is less than 35. Humoral immunity The component of the immune Hypocarbia Condition in which the amount of system involving antibodies that circulate as soluble bicarbonate ions in an arterial blood gas sample is less protein in blood plasma. than 22. Hydrostatic pressure Pressure created by the force Hypoglycemia Condition in which blood sugar (or behind the volume of water in the body. blood glucose) concentrations fall below a level 808 Glossary Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. necessary to properly support the body’s need for in a subcutaneous pocket under the skin’s surface. energy and stability. Implanting the entire device affords the IVAD the skin’s Hypokalemia The development of low sodium protection, which decreases the rate of infection, as potassium in the blood serum. well as protects the port from physical trauma. Hyporefl exive Refl exes that are signifi cantly less brisk Implied consent An assumption that an unconscious than normal. patient in danger would consent to a life saving Hyporesonant Percussion note that is dull in character procedure if awake and capable of consenting. and often indicates fl uid in the lung. Incidence The number of new cases of a disease per Hypotension A systolic blood pressure below the lower standardized group per time. An example would be 1 limit of normal. case per 100,000 per year of x disease. Hypothermia A condition that occurs if there is too Incision and drainage (I&D) A minor surgical little heat in the body’s core; a body temperature less procedure used to release pus or pressure from a site than 35°C (95°F). such as an abscess. Hypotonic Fluid that has more water and less salt Indirect statement A question that asks for an (electrolytes) than the solution on the other side of explanation that is not constrained by the question. a semipermeable membrane. In an effort to balance An example of an indirect statement would be, concentrations, the water from the hypotonic solution “Please tell me about your pain.” will cross the membrane until the two solutions are In extremis An appearance of grave illness or mortal balanced. injury. Hypoventilation Shallow respirations that can be Infarction A large area of necrosis in a tissue or organ. caused by drug overdose, head injury, or another Infl ammation A protective reaction of tissue to condition. irritation, injury, or infection, characterized by Hypovolemic A state of decreased circulating blood localized pain, redness, swelling, and sometimes loss volume. of function. Hypovolemic shock The fi rst category of the Initial assessment See Primary assessment. Hinshaw—Cox shock classifi cation, which includes Initial impression A global patient assessment made shock that arises from trauma (hemorrhagic shock) but on initial contact with a patient based on a myriad of also includes other etiologies where there is a loss of factors such as patient presentation, environmental circulating blood volume. factors, gross observation, and resources on-scene. Hypoxemia A decreased oxygen level in the blood. Injury Something that damages or harms. Hypoxia Condition in which partial pressure of oxygen Injury prevention See Prevention; Injury prevention dissolved in an arterial blood gas sample is less than strategies. 70; low oxygen concentration that causes cells to Injury prevention strategies Techniques used to go redirect their metabolic processes to anaerobic about implementing Haddon’s countermeasures, which respiration in an effort to sustain the cell. include engineering safety into products or processes, Hypoxic hypoxia Lack of oxygen, due to an oxygen educating people about the dangers, increasing or poor environment, which can lead to hypoxia. improving enforcement of laws and regulations which Iatrogenic Adverse effects or complication that results promote safety, and providing economic incentives for from a medical intervention. people to use safer products or processes. Idiosyncratic reaction Situation in which a drug Inotropy To make the heart beat harder. produces an unpredictable reaction that is not allergic Insensible loss The volume of fl uid that is lost from in nature or due to overdose and resultant toxicity, the body in the form of perspiration off the skin but often due to the patient’s genetic make-up. (1.1 liters/daily) and the vapor in the breath. Immune complex Situation in which an antibody Insight An understanding of the patient’s current has attached to an antigen and stimulates the or chronic medical condition, as well as the complement system. consequences of inappropriate treatment; the ability Immunocompetent Capable of providing immunity. to make reasonable decisions. Immunoglobulins A type of protein globulin. Five Inspection A physical examination technique that types of immunoglobulins have been identifi ed: involves looking closely at the patient. IgA, IgD, IgE, IgG (gamma globulin), and IgM. Each Inspiratory capacity The total of the tidal volume immunoglobulin fi ts into the surface of an antigen in a plus the inspiratory reserve volume, which is a key and lock fashion, linking them together. measure of the maximum air that can be inspired. Implanted vascular access device (IVAD) A Institutional Review Board (IRB) An independent central venous catheter that has the port buried ethics committee consisting of experts from the fi elds Glossary 809 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. of theology, sociology, psychology, and medicine, the police power to provide consent is not generally which is responsible for reviewing all aspects of a invoked for minor emergencies or elective procedures. proposed research project in terms of the potential Ions An atom that has a positive or negative charge due psychosocial impact and to ensure that all human to a gained or lost electron. subject research is ethical. Ischemia A defi cient supply of blood going to a body Integrity A personal commitment to a code of moral or part due to an obstruction of the infl ow of arterial ethical behavior which serves as a foundation for the blood. patient–provider relationship. Ischemic hypoxia Problems of circulation that can Intended biological effect The modifi cation a drug lead to oxygen deprivation at the cellular level. is designed to have on the function of a tissue or an Ischemic patterns Changes in an ECG as the result of organ, such as reduce fever, eliminate pain, and so abnormal repolarization. on. Isoelectric line A line on the ECG that extends from Interference Extraneous electromagnetic energy heard the end of the T wave to the start of the ventricular on the radio as crackles and dead spots. depolarization represented by the QRS complex. Internal locus of control The idea that one has the This line indicates the period of time when the ability to remain in control of a given situation. myocardium, particularly the ventricular mass, has International unit (IU) A standardized measurement been repolarized and awaits depolarization. An that reveals the quantity of a biologically active isoelectric line on the monitor and on the rhythm strip substance, such as a hormone or vitamin, required to should appear as a fl at line between ECG complexes. produce a specifi c response. Isometric Exercise using free weights. Interpretation An interviewing technique in which Isotonic In terms of exercise, resistance exercises. In the Paramedic tries to determine the meaning of terms of fl uid management, a balanced solution (equal a message based on what is said and the speaker’s water and salt on both sides of a membrane). nonverbal cues. IV bags Soft plastic solution containers that collapse Interstitial fl uid The fl uid between cells. as the solution is withdrawn, eliminating the need for Interval A segment and an ECG wave together. venting. These create a closed system that helps to Intimate space In the theory of proxemics, an area decrease the risk of outside contamination. about the size of a beach blanket where patients IV push Procedure in which a Paramedic a medication feel most vulnerable. Entry into that space is only by attaching a syringe fi lled with the medication to an permitted to those people whom the patient trusts. infusion device and rapidly injects the medication. Intracellular water The water that is within cells. Jaundice A yellowish hue of the skin, which can Intradermal Injections that place a small quantity indicate liver failure or obstruction of the bile duct. of medicine just under the epidermis and in close Joule heat Heat caused by the buildup of thermal proximity of the subcutaneous tissue. energy as a result of electricity overcoming resistance Intramuscular injection Injection deposited between from the tissues. the layers of muscle, which is a common method of J point The start of the ST segment found at the medication administration. juncture of the QRS and the ST segment, the point Intraosseous (IO) An injection into the bone marrow. where the angle from the QRS changes. Intravascular fl uid A type of extracellular water Jugular venous pressure The force at which blood found in the blood, which is primarily made of plasma fl ows throughout the venous system, which can help and constitutes about 4% of the total body weight diagnose issues in the lung and heart. (3 or 4 L). Junctional tissues A long strip of tissue below the Intrinsic rate The rate at which the pacemaker cells AV node connecting the atria and the ventricles that of the heart depolarize. is capable of independently initiating a stimulus Intrinsic trigger A stimulus prompting an airway if the SA nodal impulse should fail to depolarize spasm that originates within the body, such as through one fi rst. stress or exercise. Jurisdiction The court having authority to decide a Inverted T waves A negative T wave that’s normally legal case, typically based on location. positive and upright, which may indicate coronary Justice The application of the concept of fairness, ischemia. which implies impartiality in the administration of Involuntary consent Situation during a life or limb rewards. In terms of research, the belief that one emergency in which an offi cer can provide consent group of people should not bear all the risks of for a person in custody (e.g., a prisoner). Involuntary research when the benefi ts of said research would consent is usually reserved for true emergencies; benefi t all persons in the larger society. 810 Glossary Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. J-wire A special tightly wound spring wire with an negative electrode is on the right arm. The positive open hook at the end to prevent it from puncturing electrode is on the left arm. soft tissues, which is inserted into the hub of a needle Lead II An electrode point that notes the change during the Seldinger technique. between the right arm and left leg and provides a Kaizen Japanese concept of continual self- view of the inferior wall of the heart. The positive improvement that emphasizes process and system electrode is located on the left leg. thinking. Lead

III An electrode point that measures change Keep the vein open (KVO) A slow infusion of fl uid between the left arm and left leg. The positive designed to be just enough to keep the veins from electrode is on the left leg. occluding. Leading question A question that may direct Kefauver-Harris Act A 1962 amendment to the the patient toward an answer that might not Federal Food, Drug and Cosmetic Act that required necessarily have been given if asked in another all drugs to undergo an extensive review that not only manner; for example, asking “Was the pain ensured the public’s safety, but also reassured the crushing?” rather than “Tell me what the pain in public that a drug would do what it claimed to do. your chest was like.” Ketamine A dissociative anesthetic that provides Left anterior descending coronary artery (LAD) excellent amnesia, analgesia, and anesthesia during A coronary artery branch that provides blood to the procedures and intubation. Most notably, however, it anterior wall of the left ventricle. has minimal respiratory depression even at very high Left bundle branch A division of the bundle of His doses. that lies within the septum and serves as a further Kinematics The branch of dynamics that studies passageway for electrical impulses into the left motion apart from mass and force considerations. ventricle. Kinesics The study of nonverbal behavior in Legitimate interest A determination of which interpreting communications. individuals need access to a patient’s confi dential Knowledge base The Paramedic’s previous medical information, and the extent of the experiences, anecdotal information, and formal information they are entitled to view. medical education. Legitimization The process in which a Paramedic Korotkoff sounds Sounds heard during the infl ation listens and seeks to understand the patient and and defl ation of the cuff that are caused by the the patient’s concern, regardless of how seemingly change in the nature of blood fl ow through the artery. insignifi cant the problem. This process supports the Labor Uterus contractions which signify the start of the patient and demonstrates caring. childbirth process. LEMON law A rapid mnemonic used to predict a Lacerations A torn or ragged wound. diffi cult airway when evaluating a patient. The Landline A hard-wired telephone. elements of the LEMON law are to: Laryngeal mask airway A blindly inserted airway ■ L—Look externally for anything that will hinder device designed to be used in situations where ventilation or intubation face-mask ventilation was inappropriate but the ■ E—Evaluate the 3-3-2 rule to assess the airway invasiveness of endotracheal intubation was not anatomy necessary. ■ M—Mallampati classifi cation Laryngoscope The primary, compact, and self- ■ O—Obstruction, either new or chronic, should be contained device healthcare providers use to visualize evaluated the larynx. ■ N—Neck mobility should be determined if not Larynx Also known as the “voice box,” the upper group contraindicated (contraindicated in suspected of structures of the lower airway that contains the C-spine injury) vocal cords. Les ambulance volantes Light two-wheeled LD50 Shorthand for lethal dose 50%, the drug dosage carriages used by the French military in the early where 50% of the test animals given that dose died. 1800s that carried an attendant as well as a driver, Lead Any of the conductors connected to the often viewed as the precursor to the modern electrocardiograph, each comprising two or more ambulance. electrodes that are attached at specifi c body sites Leukocytes White blood cells, which help the body and used to examine electrical activity by monitoring fi ght off disease. changes in the electrical potential between them. Leukotrienes Slow acting substances of anaphylaxis Lead I An electrode point that measures the voltage that produce chemical effects similar to histamine and change between the right arm and the left arm. The help to prolong the infl ammation. Glossary 811 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Libel Situation in which a falsehood damaging to a Lymphedema The swelling of tissues on a limb due to person’s reputation is written or printed and then lymphatic obstruction. disseminated to the public. Lymphocytes Almost colorless cells found in the Lidocaine A common local anesthetic and blood, lymph, and lymphoid tissues, constituting antiarrhythmic drug. approximately 25 percent of white blood cells and Life-long learning The commitment made by all including B cells, which function in humoral immunity, Paramedics when they attain their fi rst certifi cation to and T cells, which function in cellular immunity. remain current with the state of the profession. Lysosomes Tiny sacs in a cell that contain enzymes Lighted stylettes Malleable stylettes with a bright which can break down proteins. light source at the distal end and a power source Macintosh blade A curved laryngoscope blade with at the proximal end. When placed in the trachea, a common sizes from 1 to 4 with a large fl ange and fl at bright, well-circumscribed light is seen in the midline surfaces to control the tongue. of the trachea. Macro-drop Administration set with a short, straight Line of sight (LOS) The path that radio transmissions line that has few obstructions, such as fi lters or take over land, which ideally are free of obstructions medication portals. It is used when volume replacement that will impede the radio waves. is needed (e.g., during a trauma resuscitation). Line-out To place a single diagonal line across any Macroglossia A state of having an abnormally large open areas of a document in order to prevent the tongue. addition of new content to a PCR by others after the Magmas Powdered drugs with particles so large that Paramedic has completed the PCR. they are visible when they are mixed, or suspended, in Lipid-soluble A substance that is able to be dissolved water. in lipids (fat). Malfeasance Wrongdoing or misconduct; for example, Lipophilic Characteristic of being attracted to lipids. if the Paramedic performed an inappropriate Liquid oxygen (LOX) Concentrated oxygen in liquid procedure (e.g., gave a fl uid bolus to a hypertensive form. head-injured patient). Liquifactive necrosis Process in which cells that are Malignant Cancerous; something that will cause harm largely lipid in content, such as the neurons of the or damage health. brain, simply liquefy upon death and leave a pool in Malignant hyperthermia A skeletal muscle their place. disease that leads to a life-threatening reaction to Literature Published reports of research. succinylcholine and some other inhaled anesthetics. Livor mortis A condition caused by relaxation of the Malpractice Failure to exercise an appropriate degree vascular bed and a pooling of blood in dependent of professional skill during a service, resulting in portions of the body. injury, loss, and damage. Loco parentis Legal doctrine that states if a child Managed health care A fi nancial system where a has been left in the custody and care of another large corporation or the government obtains health adult (e.g., a schoolteacher) then that adult has the insurance for its workers via private sources, who then authority to provide consent for medical care. gather groups of healthcare providers and obtains Lotions Topical medications mixed in water. a reduced rate in exchange for a guaranteed client Lower esophageal sphincter (LES) A functional base. The managed healthcare insurance plan then portion of the esophagus where its walls contract mandates that patients seek treatment from this inwardly, forming a physical barrier to the refl ux of preferred medical group, in essence managing the stomach contents up the esophagus. care that the patient will receive by providing medical Low priority patients Patients with relatively minor care for the lowest price. conditions who can typically be treated in a more Mandatory reporting A situation in which one is focused manner on-scene. required by law to report a crime, such as child Lozenges Medicines intended to dissolve in abuse, sexual assaults, gunshot wounds, certain the mouth. communicable diseases, and animal bites. Luer lock A needle adaptor that attaches to the Mason–Likar modifi cation Adjustment in the syringe hub by use of a twist connection, where the placement of electrodes to help Paramedics obtain adaptor on the syringe is grooved and will mate with a a more accurate 12-lead ECG, which involves moving fl ange on the needle hub. the electrodes to the shoulders and the hip rather Lymphangitis Infl ammation of the lymphatic channels than the ankle and wrist. in the skin that occurs when there is spread of an Masses A large, fi rm area of considerable size in infection from a site distal to the channel. the body. 812 Glossary Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Master problem list In a POMR recordkeeping system, complex created by the complement system which a list of the medical conditions for which a patient attaches itself to the cell’s walls and forms a tube had been, or currently was, receiving treatment. from the outside to the inside. The tube allows water Mean arterial pressure (MAP) The average blood to enter the cell, the cell to swell, and the cell to pressure in the arterial system over time, typically lysis. about 60 to 80 mmHg. Memory cells Clone cells that have a memory of the Mechanism of action The way a drug specifi cally make-up of the original cell. works upon a cell. Meniscus A concave-curved shape liquid assumes due Mechanism of injury (MOI) A description of the forces to tensions within a syringe. applied to a patient with the potential to cause injury, Menopause An age-related cessation of a woman’s such as a motor vehicle collision (MVC) or a fall. menses for an entire year, generally indicating the Medical command An immediate and direct physician end of the woman’s reproductive abilities. involvement in patient care. The physician’s authority Mentors Experienced master Paramedics who take on can be exercised either on-scene or over-the-air at graduate Paramedics as their protégés to teach them the time of an emergency. paramedicine. Medical ethics The way Paramedics behave in regard Meta-analysis A technique used when it is diffi cult to patients. to obtain a large population of study subjects, or the Medical intelligence The healthcare provider’s event being studied is relatively rare. The results process of learning from experience and past medical of several similar small studies are combined and practice and then coming to a decision. a statistical hypothesis test is applied, taking into Medical lines Sometimes called lifelines, a means of account differences in subjects and methods used adding medications directly into the circulation. before a conclusion is made. Medical oversight When a physician is involved in the Metabolic acids Acids formed during anaerobic quality assurance/quality improvement process and metabolism and amino acids formed by the provides direction, either in the form of protocols or breakdown/oxidation of proteins. education, to Paramedics. Metabolism Biochemical reactions that need to occur Medical Priority Dispatching™ A classifi cation for life processes to go on. system designed to ensure the right response gets to Metabolite A chemical produced by degradation of a the right person at the right time. medication into subcomponents that may be active or Medical record Documentation about the patient’s inactive. condition that will be used in the future by other Metaplasia Replacement of one adult cell type with physicians and allied healthcare professionals for another type of adult cell. patient care. As a part of the medical record, the Metered dose inhaler (MDI) Portable and simple- patient care report often provides vital information to to-operate respiratory device that delivers a specifi c physicians about the origin of a condition or disease. amount of aerosolized medication to the lungs. Medical restraint Any device used to immobilize a Micro-drop Administration set with

fi ne control of patient for both the patient’s and the care provider’s the infusion stream, used when careful titration of safety; may include straps, jackets, and so on. medicated fl uid is desired (e.g., when a medical Medical self-help Instructions provided to patients by patient needs a slow infusion of a drug). 9-1-1 on self-rescue actions they can take during the Micrognathia A state of having a small jaw. time before responders arrive. Milieu An environment where an action can occur. Medical utility An assumption that those with the best Military emergency medicine The largest and oldest medical prognosis should be treated with the medical EMS service, consisting of those who provide emergency provider’s limited resources. medical care to members of the armed forces. Medication-facilitated intubation The use of Miller blade A straight laryngoscope blade with adjunctive medications during intubations, either common sizes from 00 to 4 with a small and curved to provide sedation or cause muscular paralysis to fl ange designed to open a conduit to the larynx on protect patients and improve their quality of care. the right side of the mouth and hold the tongue in the Medulla oblongata The part of the brain responsible midline to the left side of the mouth. for controlling involuntary vital functions; the Minimum data sets Certain fi elds with requested brainstem. information that must be completed on a PCR or other Membrane attack complex (MAC) In cases where form. the body does not recognize the bacteria and cannot Minute ventilation A measure of the total volume mount an effective antigen—antibody defense, a of gas that passes through the lungs in a minute. It Glossary 813 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. equals the respiratory rate (RR) times the volume per receptors and indirectly open ion channels that cause breath (Tidal Volume, or TV). depolarization. Muscarinic receptors, by defi nition, Misfeasance To perform a legal action in an illegal are more sensitive to muscarine, a naturally occurring manner; for example, if the Paramedic performs the chemical found in mushrooms, than to nicotine. correct procedure but does so incorrectly. Mutation A change in the DNA sequence of one gene. Mitochondria The largest organelle in the cell, found Myocardial infarction The death of myocardial cells. outside a cell’s nucleus, which produces energy. Myocardial ischemia A condition that occurs prior Mitosis The process of cell division. to myocardial cell death in which the heart tissue Mobile data terminal Laptop or handheld computers is slowly or suddenly deprived of oxygen and other inside a vehicle a Paramedic can use to create a nutrients. downloadable document for transmission over a Myocardium A muscular layer that actually performs telephone line, via modem, over the Internet, or by the heart’s work by contracting forcefully and using wireless technologies. ejecting blood from within the heart’s chambers. Mobile subscriber units (MSU) The various varieties Myoglobulinuria A condition in which the protein of cellular phones for use within a cellular radio products of muscle breakdown clog the kidneys. system. The three main varieties are the portable Narcotic The hallucinogenic effects of opiates, thought cellular telephone, the transportable cellular to be the result of stimulation of the sigma receptors telephone, and the mobile telephone. located in the limbic system. Modifi ed chest Lead 1 (MCL1) An alternative Narcotics A class of drugs known for their ability to ECG lead Paramedics may use to monitor patients induce a profound state of sedation. instead of/in addition to Lead II. MCL1 simulates the Nares The openings to the nose; nostrils. precordial lead V1, one of the six precordial leads of a Nasogastric tube A single-lumen tube passed through 12-lead. the nose into the stomach to evacuate air from the Morality A personal code of conduct. stomach. Moral obligations Certain mores that go beyond the Nasotracheal intubation The process of aiding basic human rights which every patient enjoys; for respiration by placing an endotracheal tube through example, an off-duty Paramedic’s moral obligation the patient’s nostril and into the trachea. may be to provide care when coming in contact with National Association of EMTs (NAEMT) A an injured person. professional organization, founded in 1975, whose Morbidity The incidence of disease. mission is to represent the views and opinions of all Morphology The shape of a QRS complex wave. prehospital care providers. Mortality The state of death. National Centers for Injury Prevention and Motion A request sent to a judge for some action Control A federal agency tasked with injury (i.e., dismiss the case, order a party to do something, surveillance. postponement, cease and desist orders, etc.). A motion National EMS Core Content Created under the can be verbal, but is most often a written request that leadership of the National Association of EMS contains pertinent points for the judge to consider. Physicians (NAEMSP) a curriculum that defi nes the Mucolytics Drugs that thin mucous secretions and entire universe of disorders, diseases, syndromes, and physically break down the viscosity of mucus by skills that an EMS provider might encounter and for breaking apart the mucoprotein structure. which he would be expected to provide emergency Multiple organ dysfunction syndrome (MODS) A care. failure of two or more organ systems. National EMS Education Program Accreditation A Multiplex Radios that permit the transmission of audio designation that assures students their EMS education signals as well as data. will meet national standards and assures the public Municipal EMS service A government-fi nanced that graduates of those educational programs will be and administered EMS system that may exist as an competent providers. independent entity or cross-trained with the police or National EMS Education Standards Created under fi re department. the leadership of the National Association of EMS Murphy’s sign Right upper quadrant tenderness that Educators (NAEMSE), the basis for EMS instruction that worsens when the patient takes a deep breath while provides direction for EMS educators regarding both the quadrant is palpated. A Murphy’s sign indicates the core content and the scope of practice. gallbladder infl ammation National EMS Scope of Practice (NEMSSOP) Muscarinic receptors Parasympathetic Created under the leadership of the National neuroreceptors that are slower than nicotinic Association of State EMS Offi cials (NASEMSO), an 814 Glossary Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. organizational plan that clearly defi nes four levels of Neurotransmitter A chemical messenger that EMS providers and identifi es the knowledge and skills transmits a nervous signal across the synapse. required for each level. Nicotinic receptors Chemical receptors from National Formulary (NF) A drug reference manual the parasympathetic nervous system found in the that lists medications which are approved for central and peripheral nervous system as well as prescription. It contains specifi c chemical information the neuromuscular junction with skeletal muscles. that is more helpful to the pharmacist and Cholinergic stimulation of nicotinic receptors is quick manufacturer than the physician. in onset and short in duration, causing a sodium infl ux National Registry of Emergency Medical and local depolarization. Technicians (NREMT) An organization that Nitric oxide (NO) A colorless, poisonous gas involved provides a process of practical testing and written in oxygen transport to the tissues, the transmission of examinations for the certifi cation of Paramedics, nerve impulses, and other physiological activities. providing proof that the individual being licensed is NKDA Acronym that stands for “no known drug minimally competent to provide a specifi ed level of allergies.” care. The majority of states currently accept National No apparent distress (NAD) An appearance of not Registry certifi cation for state licensure. having diffi culty. National Standard Curriculum (NSC) A seminal Nociceptors Pain receptors in the body that respond document that defi nes the scope of practice for many to chemical, mechanical, or thermal stimulus. EMS providers distributed by the National Highway Noisy Characteristic of an ECG signal that is of poor Traffi c Safety Administration (NHTSA). quality and produces an unreadable tracing. Nature of illness The history of the present patient’s Non-depolarizing neuromuscular blockers One illness, often reported by the patient himself or the of the two major classes of neuromuscular blockers; patient’s family. competes with acetylcholine for the receptor but does Necrosis A physiological process in which living cells not cause the receptor to fi re. die, often due to disease, injury, or some other Nonfeasance A failure to perform the correct or pathological state. required procedure, which would be an error of Needle cricothyroidotomy A type of surgical airway omission; for example, if a Paramedic were to arrive performed by piercing the cricothyroid membrane on-scene of a cardiac arrest and the defi brillator with a large bore needle and catheter, allowing rapid failed because of a dead battery, which the Paramedic access to an otherwise obstructed airway. should have checked during routine maintenance. Negative pressure ventilation A mechanical Nonjudgmental Providing services based upon human ventilation technique in which a negative pressure need, with respect for human dignity, unrestricted environment is created around the patient’s chest, by consideration of nationality, race, creed, color or thus sucking air into the lungs. An iron lung is an status. example. Non-malfeasance A concept suggesting that no act of Negligence A failure to exercise the degree of care harm will be done during a medical treatment. that a prudent person would exercise. Nonrebreather face masks (NRB) Oxygen masks with Negligence per se Situation in which a Paramedic an oxygen reservoir that can deliver up to 80% FiO2; commits a criminal act, and the patient is injured as a they do not deliver 100% FiO2 because there will always result of that criminal act. The assumption is that the be some room air mixing through the open side port. Paramedic’s negligence fl ows from the criminal act. Nonspecifi c ST changes Situation in which the ST Neostigmine An acetylcholinesterase inhibitor that segment changes do not fi t a pattern of ischemia, can be used to reverse the effects of the competitive nor are they contributory toward another diagnosis. (non-depolarizing) NMBAs. Causes of nonspecifi c ST changes include improper Neuroleptics Major tranquilizers that prevent nausea. lead contacts, electrolyte abnormalities, drug-induced Neuromodulator Substances that inhibit the changes, hyperventilation, and even a drink of cold transmission of painful sensations to the brain and water. spinal cord by adjusting, or modulating, the rate of a Norepinephrine The chief neurotransmitter used in neuron’s discharge. the sympathetic nervous system. Neuromuscular blocking agents (NMBAs) Normal saline (NS) A solution of 0.9% sodium chloride Medications that block transmission of nerve impulses in sterile water (0.9% NaCl) that contains the same to skeletal muscle at the neuromuscular junction. amount of salt as does blood. NSS has become an Neuroreceptor A chemical receptor that receives EMS standard solution in many systems because it is messages from the neurotransmitters. compatible with all medications as well as blood. Glossary 815 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Normal sinus rhythm An optimal rhythm to provide the fi rst strip of tape, which will absorb any tension adequate fi lling of the ventricles and suffi cient on the tubing and potentially prevent the IV catheter ejection of blood for perfusion. from being displaced. Normocardiac A heart rate between 50 and 100, Oncotic Caused by swelling (e.g., oncotic pressure). which is considered to be normal.

On-line medical control Medical command technique Nosocomial A hospital-acquired infection. in which physicians can give medical direction and Notary public A public offi cer recognized by the exercise medical command via the base radio. court who can verify the Paramedic’s writings to Open-ended questions Questions that allow the authenticate them as evidence. patient to express himself without restriction, with Null hypothesis When considering the results of a answers that can be used as a springboard to other research study, the supposition that the treatment questions. Open-ended questions usually begin with did not create changes (i.e., any changes are purely words like “how,” “what,” or “could” and ask for an random and coincidental). The purpose of the study is explanation. to determine if the null hypothesis is true or false. Operational competence A Paramedic knowing Nutritional fl ow The daily process of excretion and how the various team members interact, knowing an reabsorption of approximately half the nutrient- organization’s policies and procedures, and possessing laden fl uids in the body that is essential to the body’s situational awareness. sustenance. Opsonization A process in which the plasma proteins Nystagmus A fi ne tremble of the eye when holding mark resistant bacterium by attaching fragments of a lateral gaze; unequal movement or oscillating eye themselves to the bacterial cell wall, thus enhancing movements that are usually involuntary. the impact of the leukocytes. Obesity A growing health crisis when an individual’s Optic Pertaining to the eyes. body mass index is 30 or greater; a common layperson Orientation A person’s awareness of himself in terms defi nition of morbid obesity is 100 pounds over ideal of place and time. weight. Orogastric tube A single-lumen tube passed through Observational study In contrast to the descriptive the mouth into the stomach to evacuate air from the study, a study that asks a question and poses a simple stomach. explanation or hypothesis. To have a scientifi cally Orotracheal intubation The most common technique valid result from an observational study, one must used to intubate patients, in which a laryngoscope is control extraneous confounding variables that could used to visualize the larynx and the vocal cords, and account for the desired change. an endotracheal tube is observed to pass through the Obstructive shock The fi nal category of the Hinshaw– vocal cords. Cox shock classifi cation, which deals with the physical Orphan drugs Drug therapies for rare or uncommon impairment of forward blood fl ow despite an effective diseases, which generally are unprofi table for pump, an adequate blood volume, and a normal manufacturers to produce because the drugs are so vasculature. Examples of obstructive shock include rarely used. massive pulmonary clots, embolism, and a collapsed Orthostatic hypotension An abnormal decrease lung (pneumothorax), which proceeds to crush the in blood pressure that occurs when someone heart as well. stands up. Ockham’s razor A theory that simply states that if Orthostatic vital signs Vital signs that change with all things are equal, the simplest solution tends to be position. For example, when an individual changes the best one. In other words, common things occur position from lying down to standing, the blood commonly. pressure normally has a tendency to drop due to Oils Substances that have been extracted from plants gravity. for centuries for their use as food additives as well as Oscilloscope An electronic instrument that medications. produces an instantaneous trace on the screen of Ointments Topical medications placed in either a cathode-ray tube corresponding to oscillations of lanolin, an oil from sheep’s wool, or petroleum jelly. voltage and current, used in some cases to measure Oliguria An decreased output of urine, below 20 mL electrocardiograms. per hour. Osteoporosis A loss of calcium from the bones Omega loop Creation of a stress loop when securing an secondary to a decrease in hormones. intravenous administration set tubing to the patient. Otic Pertaining to the ear. Initially, a strip of tape is laid across the adaptor and Otitis media A middle ear infection marked by pain, against the skin. Then a loop of tubing is taped across fever, or hearing loss. 816 Glossary Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Outcomes evaluation A matter of comparing the Paramedic fi eld diagnosis See Paramedical level of injury or illness before and after an injury diagnosis. prevention program. Paramedical diagnosis A broad and comprehensive Over-the-counter (OTC) Nonprescription medications identifi cation of a syndrome, a group of signs and that can be purchased by the public without a symptoms that suggest a disease, or a primary prescription so patients can self-treat minor illnesses. disorder of homeostasis, such as hypoxia, in a patient Ovum A female gamete; the egg in a female fertilized upon assessment by the Paramedic. by a sperm cell to create an embryo. Paramedicine A special subset of medicine that Oxygenation The ability to move oxygen from the air Paramedics provide in the out-of-hospital setting. in the lungs into the blood. Parasympathetic nervous system The portion of p value The probability of random chance causing the the autonomic nervous system responsible for the changes in a clinical trial, rather than the treatment. body’s involuntary vegetative functions including An acceptable p value is arbitrarily assigned by the digestion, heart rate, and the like, largely controlled researcher prior to the start of the study and is by the vagus nerve. These functions are summarized symbolized as . as “feed and breed.” Packed red blood cells (PRBC) Blood component Parasympathomimetic A chemical agent that mimics formed by removing nearly all of the plasma from the action of acetylcholine. a unit of blood and adding a small volume of Parenteral A method of drug administration that preservative to the unit. bypasses the gastrointestinal system, such as Pain threshold The amount of stimulus required to injection, which is preferred during an emergency elicit a pain response in a person. because of the rapidity of onset of the medication’s Palliative care Measures used to increase comfort and action as well as predictability of the drug levels. reduce pain, such as medication. Past medical history (PMH) Signifi cant historical Palpation Evaluation that involves the provider placing information necessary to determine the nature and his hands or fi ngers on the patient’s body in an effort potential severity of the patient’s illness or injury. to detect any abnormalities. All patients should be questioned about issues like Palpitations The sensation of one’s heart having an chronic illnesses, medications taken, allergies, and irregular and/or rapid heartbeat. use of tobacco, alcohol, or other drugs. Pandemics Outbreaks of diseases that spread Pathogen An organism that causes an infectious throughout a country or a region, which may reach disease. disaster proportions if not prevented or controlled in Pathogenesis The sequence of events—at the an appropriate fashion. molecular and cellular level—that leads to organ Papillary muscle Muscles that stabilize, open, dysfunction. and close the valve leafl ets with each myocardial Pathologic Physical changes as a result of disease. contraction. Pathophysiology The study of the causes of suffering Paradigm blindness The attitude that “we have in the normal human condition. always done it this way.” Paradigms can sometimes Patient advocate An individual who fi ghts for the become barriers to innovation and improvement. rights and wishes of the patient in terms of health Paradoxical respiration A disruption in normal care. Whenever a Paramedic acts to help a patient respiration in which, during inhalation, the fl ail obtain needed health care, he is acting in the segment is drawn inward by the negative pressure advocacy role. in the chest rather than expanding outward with the Patient autonomy The patient’s ability to control rest of the chest wall. During exhalation, the opposite her person and her personal destiny through decision occurs due to the increased pressure in the thorax making. Followed to its logical conclusion, patient during exhalation. autonomy implies that patients could decide to do Paraglossal approach An intubation technique nothing about a fatal illness, a decision that might that involves inserting the entire length of the lead to their own demise. laryngoscope blade blindly into the esophagus and Patient care report (PCR) Documentation completed then slowly withdrawing the blade under direct by the Paramedic indicating the care provided to a visualization. particular patient. Paramedic The highest level of EMS provider, Patient concordance The process of shared decision whose skill level and education includes advanced making between the healthcare provider and patient. assessment and diagnosis of syndromes and disorders Pattern recognition A tendency to quickly label an ECG and the treatment thereof. rhythm because it looks like another ECG rhythm seen Glossary 817 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. previously, which is poor practice because it negates the patient compartment at will, all the while nuances that differentiate one wave from another. transmitting and receiving critical patient information. PCR audits A careful review of the patient care report Personal space In the theory of proxemics, the documentation for specifi c data that allows healthcare area where a patient would engage in a one-on-one managers, EMS administrators, and EMS physicians to conversation. This personal space, about one and one- ensure that acceptable patient care is provided to all half feet to four feet, is the distance within which most patients equally. Paramedics initially interview patients for a history. Peak expiratory fl ow The maximum velocity of gas Pertinent negatives Those symptoms which, if movement during exhalation. present in a patient, could indicate a more serious Peak-load staffi ng EMS practice in which, during underlying problem. predictable hours of high demand, additional pH scale A measure of the differing degrees of acidity ambulances are placed in-service at strategic or alkalinity in a substance. The range of pH is from locations. 0 to 14, with 7 being neutral. Values lower than 7 PEARLS A mnemonic (partnership, empathy, apology, are acids, values higher than 7 are bases, and pure respect, legitimization, and support) that includes the distilled water is neutral (pH is an abbreviation for qualities needed to provide for a strong Paramedic– potential hydrogen). patient relationship. Phagocytosis A process in which neutrophils destroy Peer reviewed An article or research study that was bacteria by engulfi ng them. critically appraised by experts in the fi eld for validity. Pharmacodynamics The study of how drugs come to Penumbra A predictable pathway of cell changes create their therapeutic effect. leading to cell necrosis and myocardial infarction. Pharmacogenomics A combination of pharmaceutical Percussion The act of lightly but sharply tapping the research with the study of the human genome. body surface to determine the characteristics of the Pharmacokinetics The study of how drug absorption, underlying tissue. distribution, detoxifi cation, and elimination affect a Percussion note The sounds that result from the drug’s therapeutic value. act of percussion. Air-fi lled structures will produce Pharmacological effect A new or different effect a hollow, tympanic percussion note similar to that a drug generates in the body other than what was of a drum. Fluid-fi lled structures will produce a dull expected. percussion note. Solid structures will provide a loud, Pharmacology The study of drugs. well-defi ned percussion note. Pharynx The area of the airway composed of the Percutaneous central venous catheters (PCVC) spaces behind the nose (the nasopharynx) and the oral A central venous access device inserted into the cavity (the oropharynx). deep veins via the subclavian vein (in the chest), the Phenotype The visible outward expression of the internal jugular vein (in the neck), and the femoral chromosome, which is the result of the genetic vein (in the groin). infl uences of both parents. Percutaneous cricothyrotomy A surgical technique Phlebotomy

The act of drawing or removing blood used to gain entry to the trachea through placement from the circulatory system in order to obtain a of a needle, then guidewire, then a small bore sample for analysis and diagnosis. tracheostomy tube in a rapid fashion with less Physical examination Also called an exam, an bleeding than a traditional surgical cricothyrotomy. assessment of the patient from head to toe in an Pericarditis An infl ammation of the pericardial sac effort to detect signs associated with a disease or that surrounds the heart. condition. Pericardium The membranous sac fi lled with serous Physician extenders Allied health professionals who fl uid that encloses the heart as well as the roots of the work under the license granted to the physician. aorta and other large blood vessels. Physician’s Desk Reference (PDR) A reputable Peripherally inserted central catheter (PICC) A source of information about prescription and over-the- very long central venous access catheter placed within counter medications; a compendium of manufacturer a vein in the antecubital fossa that is threaded into drug-prescribing information which is usually found the vena cava while under fl uoroscopy. in a package insert required by law to accompany all Peritoneum The inner lining of the abdomen. medications. Persistent vegetative state (PVS) A permanent Physician’s Order of Life-Sustaining Treatment state of unconsciousness. (POLST) A more detailed description than a DNR Personal digital assistants (PDA) Personal palm order of the patient’s wishes, placed in the form of a computers Paramedics can use as they move about physician’s order. These forms are generated through 818 Glossary Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. a discussion between patients and their physician emergency services while still in the fi eld and to that addresses specifi c situations including utilizing transmit critical information to the emergency artifi cial hydration, nutrition, intubation, antibiotics, department. and other medical therapies. Point of service (POS) A managed care system with Physiologic A physical loss of cells as a result of the qualities of both an HMO and a PPO. The patient is normal changes of aging or simple disuse; a natural allowed to choose a healthcare provider from among development of cells. a list of preferred care providers (PCP) but may elect Physiology The study of the body’s functions, in its to see another “out of system” provider, without a normal human condition, which focuses on the physical, referral, at a substantially higher copayment and/or mechanical, and biochemical processes that go on deductible, similar to a fee-for-service arrangement. inside the body every day (i.e., how the body works). Polarity The direction of a QRS complex wave. PIER A model public education system developed by Portable radios Radio devices that can be carried the National Highway Traffi c Safety Administration from place to place. (NHSTA) which stands for public information, Positional asphyxia Situation in which a patient education, and relations. in excited delirium develops hypoxia and goes into Piggyback infusion The process of administering cardiac arrest when restrained prone, particularly if a medication infusion by attaching the secondary hobble restrained. intravenous line containing the medication to a Positive pressure ventilation A mechanical primary intravenous line to eliminate the need for a ventilation technique in which the pressure in the second intravenous line. patient’s airway is increased, thus forcing air into the Pitting edema The amount of indentation produced lungs. Intubation or a bag-valve mask are examples. when the edematous limb is pressed over the tibia by Postmortem Specifi c changes within the body that are the examiner’s fi nger. associated with death. Placebos Inactive drugs used in research trials that Post-traumatic stress disorder (PSTD) According appear similar to the actual drug in order to create to the Diagnostic and Statistical Manual, the blinding for the participants. development of “characteristic symptoms following Placenta The vascular organ that connects the unborn exposure to an extreme traumatic stress involving child to the mother’s uterus, providing safety and direct personal experience of an event that involves nutrition during its development. actual or threatened death or serious injury, or other Plain English transmissions The use of everyday threat to one’s physical integrity; or witnessing an speech to transmit information rather than using event that involves death, injury or a threat to the codes or jargon. physical integrity of another person.” Plantarfl exion The ability to push the toes downward Potable infusions Process of boiling water over the and away from the tibia. top of medicinal herbs and immediately drawing off Plaque Fatty lesion formed in the artery as a result of the solution. atherosclerosis. Potent Chemically or medically effective; strong. Plasma cells Cells that generate antibodies. Potentially infectious materials (PIM) Any Platelet See Thrombocytes. substance with the ability to transmit bacteria to Platelet plug A concentrated mass of platelets that another material. serve as a short-term fi x to a plaque rupture. Potentiation Situation in which one drug increases the Pleura The delicate serous membrane that lines each effectiveness of another drug. half of the thorax and is folded back over the surface Power The ability to attribute the changes in a of the lung on the same side. research study to the treatment rather than chance. Pleural effusion Excess fl uid that builds up in the Predictable injury pattern Characteristic injuries fl uid-fi lled space that surrounds the lungs, which can associated with a particular mechanism of injury. cause diffi culty breathing. Preferred provider organization (PPO) A managed Pneumothorax Condition in which air or another gas is care system that serves as a modifi ed fee-for- present in the pleural cavity as a result of disease or service schedule, permitting patients to choose their injury. healthcare provider from among a roster of approved Point The end of a needle, often cut obliquely in such a physicians. fashion that a sharp leading edge is created. Prefi x An affi x placed at the beginning of a root word Point of care Testing done in the fi eld by the to modify that root word; for example, adding the Paramedic, such as capillary blood draws, which prefi x “un-” to the root word “do” makes “undo,” the enhance the Paramedic’s ability to provide immediate opposite of do. Glossary 819 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Pre-induction agents CNS depressants administered Process server A person hired by an attorney to as a premedication before the introduction of deliver a summons and complaint to the defendant in anesthesia to decrease the incidence of fear or panic a case. (anxiolysis) or combativeness (sedation) in the patient. Prodrugs A precursor of a drug that is converted Preload The volume of venous blood entering the heart into its active form in the body by normal metabolic during diastole. processes. For example, heroin is a prodrug that, when Prescription drugs Drugs that cannot be dispensed by acted upon by the liver, metabolizes into morphine. a pharmacist without the written or verbal order of a Product liability The responsibility a manufacturer has physician or a mid-level healthcare provider, such as a to ensure a drug (or other product) is not defective physician’s assistant. (unfi t for its suggested use or results in harm to the Pressured speech Condition characterized by a consumer). patient speaking so fast it appears she has an urgency Professional development Steps a Paramedic may or pressure to speak quickly. take to continue advancement of his or her EMS skills, Preventative maintenance (PM) A program that which may include attendance at state and national forestalls the incidence of failure, thereby decreasing EMS conferences or regional workshops, consultation the incidence of injury and potential litigation. with medical directors for guidance and education on Prevention The steps taken to avoid illness or injury. new technologies, and review of EMS trade journals. Primary assessment The Paramedic’s initial Prognosis The expected outcome from a disease, evaluation performed to fi nd and manage any life- determined by a culmination of modifi able risk threatening injuries or conditions the patient might factors, nonmodifi able risk factors, and the have by assessing for (and correcting, if possible) any availability of treatments. threats to airway, breathing, and circulation. Progress notes In a POMR recordkeeping system, new Primary infusion A continuous intravenous set entries in the medical record. to which other medications may be added as Pronator drift An indicator of upper motor neuron supplements. weakness that is tested for by asking the seated Primary rhythm The main heartbeat. patient to hold her arms out with the palms facing the Prime wave The fi rst wave in a QRS complex in a ceiling and then close her eyes. The test is positive if situation where a wave repeats itself. The prime wave one arm drifts away from the starting position. is represented by a capital letter and the second Prospective research The most scientifi cally valid wave is represented by a lowercase letter. For research, in which an attempt is made to account for example, a proper notation of a QRS might read RSr. all predictable or known confounding variables, to Primum non nocere The duty to “fi rst, do no harm.” control those variables, and then add a treatment. If PR interval The distance from the beginning of the P change occurs, then it may be reasonable to conclude wave to the start of the QRS complex. that the treatment may have caused that change. Privacy offi cer An offi cer at a healthcare agency Prostaglandin A chemical mediator released from responsible for providing patient record security the mast cell that creates the sensation of pain, and recording security awareness training of all although its primary function is to increase vascular employees, as well as implementing a privacy permeability and smooth muscle contraction later in protection plan within the agency. the infl ammatory response. Private line (PL) See Coded (or tone) squelch. Protected health information (PHI) Facts from a Problem-oriented medical recordkeeping (POMR) patient’s medical record that are not to be dispersed Recordkeeping system in which a master problem list to the public without authorization. records the medical conditions for which that patient Protective custody Situation in which a law had been, or currently was, receiving treatment. enforcement offi cer assumes temporary custody of Indexed as such, new entries in the medical record a child in order for the child to receive medical care would be placed into the patient’s fi le under the after the parent refuses to give consent. problem listed. All healthcare professionals, from Protocols A written set of mandatory instructions physicians to nurses to dieticians, would place their for the Paramedic to use in specifi c situations in entries into the patient’s record. This system provides the absence of the physician. Protocols, almost by some order to the records needed by hospitals, defi nition, assume that one patient’s situation is the medical specialties, and allied healthcare providers— same or similar to another patient’s condition in the all of whom need the same information. same situation. Process evaluation A measurement of the means Proxemics A theory based on the concept that four used to carry out a program and how successful it was. spaces surround a person—intimate space, personal 820 Glossary Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require

it. space, social space, and public space—which provide medicines. The law further stipulates that if a varying levels of comfort when people move within medicine contains any of the 11 “dangerous” drugs, them. then the drug(s) have to be listed on the label. Proximate cause The immediate or direct reason why Purkinje fi bers Cardiac muscle fi bers that connect something occurred. In legal terms, the action that directly with the ventricular myocardium, allowing the created an injury or reason for a claim. ventricles to contract nearly simultaneously with the Prudent layperson standard An approach to defi ning atrioventricular node, creating a functional syncytium. an emergency that simply estimates if another citizen, Pursed lip breathing A sign of increased work of not a physician, who was in the same or similar breathing, in which the patient puckers his or her circumstance would think it appropriate to call EMS. lips while exhaling, providing some resistance to Public Health Model A framework showing the exhalation that provides pressure to keep the alveoli connections between host, agent, and environment in open. preventing injury. Putrefaction A process of decomposition within Public Health Service A federal program which the body characterized by greenish discoloration, makes up a key portion of the Department of Health secondary to hemolysis of blood, and slippage of and Human Services. With 5,700 commissioned health the skin from the skeleton, due to breakdown of services offi cers and 51,000 civilian employees, all subcutaneous fat. led by the Surgeon General, the current United States Pyelonephritis An infection of the upper urinary tract Public Health Service provides support to county and and kidney. state Public Health Departments as well as health care Pyrexia A fever that makes the body’s environment to medically underserved areas. hostile to bacteria. Public information offi cer (PIO) An EMS agency Pyrogen Chemical mediator that produces fever. employee whose responsibility is to interface with the Pyrogenic reaction A devastating systemic news media and provide public information. complication of intravenous therapy that occurs Public safety access point (PSAP) A centralized when a contaminated fl uid, or fl uid run through a communications center which runs 24 hours a day, contaminated administration set, is infused and leads seven days a week, and contains the entire 9-1-1 to nearly immediate sepsis. operation; a place where a service callback or QRS complexes A combination of two or more ECG additional emergency information would be available. waves, which combine in predictable ways to describe Public space In the theory of proxemics, the area one other cardiac events and are the basis for ECG would occupy with a stranger without fear but with an interpretation. ability to fl ee if danger should arise. Quadrageminy Situation in which ectopic beats occur Public trust An understanding between the patient every fourth beat. and the Paramedic that the patient will be treated Quality assurance (QA) Verifying a program’s with dignity and respect in the same manner a compliance with established standards. physician would treat the patient. Quarantine The practice of isolating diseased Pulse oximetry A noninvasive measurement of the individuals from the larger community. percentage of hemoglobin in arterial blood that is Quickening Fetal movements during the second bound to oxygen molecules. trimester that serve as the fi rst signs of life. Pulse pressure The difference between the systolic Q waves Pathologic waves on an ECG that indicate and diastolic blood pressures. The pulse pressure can electrical silence (i.e., no depolarization) in a certain provide the Paramedic with an indication about the portion of the ventricular wall. blood volume status or compensation for illness in a Radial pulse A measure of the beats created by blood given patient. fl ow taken at the wrist over the radial artery. Pulseless electrical activity (PEA) A situation in Radio head A small remote radio control panel placed which the patient displays electrical activity in the in the driver’s and/or patient compartment of an heart but no signs of contraction; an electrical rhythm emergency vehicle. The actual transmitter is usually without a pulse. placed in a different location in the vehicle. Punitive damages Money paid to reimburse an Range A certain set of acceptable physical parameters individual for more than just the actual damages the body uses to try maintaining a normal equilibrium. suffered that prompted a court case; a monetary fi ne Rate counter A digital readout on some ECG monitors designed to “punish” the loser of the case. that measures the number of ECG complexes that pass Pure Food and Drug Act of 1906 A law that in a minute, usually counting the tallest, or deepest, prohibits the use of false or misleading claims about wave on the ECG. Glossary 821 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Reasonable accommodations Actions taken by an Relative bradycardia A sinus rhythm with a rate that employer to make a workplace more accessible for a is too slow for the patient’s metabolic needs. person with special needs, such as adding ramps or Release of information A written authorization elevators. allowing documents to be given to an attorney. Rebound tenderness Tenderness that becomes worse Reliable Giving the same result on multiple trials. when the pressure is suddenly released during palpation Remission Situation in which the body’s defenses, or that may indicate irritation of the peritoneum. medical treatment, may force the disease into a non- Recanalization The process of re-opening an artery to active state. Remission does not mean the patient has restore blood fl ow. been cured, but rather means the disease has been Reception The process of interpreting a sent message, stopped. which may be infl uenced by both physical and cultural Remodeling To change the shape of something, such factors. as the interior chamber of a ventricle. Receptor The portion of a cell that attracts a certain Repeaters Radios that pick up, amplify, and then molecule. retransmit a radio transmission, which can extend the Reciprocal changes ST-segment depressions seen on range of a VHF almost indefi nitely. the 12-lead ECG in leads that face the wall opposite of Repolarization The restoration of a polarized state those with ST-segment elevations. across a membrane, as in a muscle fi ber following Recovery For cells, a return to a former functional contraction or the recovery of the myocardial cell. capacity. For a person, a return to health. Rescue devices Airway management tools used when Reentry phenomenon The reexcitation of a region intubation is not successful, such as a blind insertion of the heart by a single electrical impulse, which may airway device. cause ectopic beats, tachyarrhythmia, or an abnormal Residual Physical or chemical changes that remain in conduction mechanism. a patient after an encounter with a disease, such as Refereed A review process in which an editor will scars or hemiplegia. typically distribute an article to a panel of expert Resistance The second stage of the general Paramedics, who offer input and edit the article. adaptation syndrome, during which the body attempts The article is returned to the author, who revises the to reestablish homeostasis, utilizing the endocrine article based on the edits. and/or the immune system. Reference librarian A librarian trained in research Respect High regard based upon a nonjudgmental techniques who can help researchers develop a search attitude toward the patient. strategy to identify which resources, such as articles, Respiratory acid Acid in the body formed when excess will be most helpful in a study. carbon dioxide reacts with water to form carbonic Referred pain Pain from one source transmitted to acid (H2CO3) before conversion into bicarbonate, other parts of the body, via common nerve pathways. which is the intermediary step in carbon dioxide Refl ected path When using the radio wave transport. phenomenon of bounce, using enough refl ective Resting membrane potential A difference in the surfaces so that the redirected radio transmission will electrical potential between the outside of the cell roughly result in the intended direction of travel. and the inside of the cell while in a resting state. Refl ection An interviewing technique in which the Reticular activating system (RAS) A complex Paramedic repeats the patient’s words, which may network of interconnected refl exes in the brainstem encourage additional responses. Refl ection is helpful that maintains wakefulness. because it typically doesn’t interrupt the patient’s Retrospective research Research technique in which train of thought. a Paramedic looks at past practice, typically from Refractory Unable to respond to a new stimulus. patient care reports, to determine how to resolve a Refusal of medical assistance (RMA) A situation in current issue or question. which a patient can consent to a medical procedure, Re-uptake The reabsorption of a neurotransmitter and yet still refuses care. by a neuron following impulse transmission across a Regulations Rules established by a government synapse. department to regulate the conduct of citizens. Reverse R wave progression The loss of an R wave Regurgitation A backfl ow of blood into the atria. progression, which is suggestive of an anterior wall AMI. Rehabilitation Steps such as taking a rest break, Reverse use- (rate) dependent Drugs that prolong eating some food, drinking fl uids, and using lavatories the repolarization of normal myocardial tissues, as that help EMS responders handle stress more electrographically demonstrated by a prolonged QT effectively while at the scene of a prolonged incident. interval. 822 Glossary Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Rhabdomyolysis A breakdown of skeletal muscle R wave progression A series of changes in the releasing cell contents including myoglobin. primary defl ection of the QRS from negative in V1 to Rib retractions Situation in which the work of positive in V6 in a normal 12-lead ECG. breathing increases and more effort is needed to SAFE-R A crisis intervention model consisting of fi ve generate the negative pressure in the thorax required steps: stimulation reduction, acknowledgement, for inspiration. When this happens, the skin between facilitation, explanation, and return or restoration. the ribs is pulled inward because of this negative Safety offi cer In a large emergency situation, an pressure in the chest. individual assigned to maintain scene safety for the Right Something to which a person is entitled based on responders. society’s sense of fair play. Saline locks Process of fi lling the intermittent infusion Right bundle branch A division of the bundle of His device with saline to seal, or lock, the device and that lies deep within the myocardium and serves as a prevent thrombus formation. further passageway for electrical impulses to the right Salvo see Run of ventricular tachycardia. ventricle. Satellite phones Satellites that radio waves are sent Right chest leads ECG recording technique in which to, in which they literally bounce off the satellite and the V4 to V6 wires from the left chest electrodes are return back to Earth, bypassing obstructions such as switched over to the same relative position on the mountains. surface of the right chest and the ECG is rerecorded as Scanners Multiband radio receivers that monitor V4R, V5R, and V6R. several radio frequencies, including those used by Right coronary artery (RCA) Cardiac artery that cellular telephones. provides blood to the right atrium and ventricle and Scene safety Steps taken to ensure the Paramedic’s the inferior portion or wall of the left ventricle. well-being when responding to an emergency Rigor mortis A stiffening of the muscles, which often situation, such as rerouting traffi c, assessing for occurs after death. threats, securing unstable areas, and the like. Risk The likelihood that a situation could lead to harm. Schizokinesis A physiological theory that suggests Risk factors Traits or practices that tend to make past

painful experiences, unconsciously recalled by a person more or less vulnerable to a disease as trigger words, can elicit an autonomic nervous system compared to another person. response. In some cases, this response could be Risk management A plan that emphasizes safety and harmful to the patient. whose goal is to reduce Paramedic injury in an effort Scientifi c method The acquisition of knowledge to promote a culture of safety in an organization. through objective observation and considered reasoning. Risk manager An individual in an organization who Sclerosis An infl ammation, thickening, or hardening of identifi es known hazards and then tries to mitigate a body part. those hazards. Scope of practice The duties and responsibilities that Root A word, often supplemented with prefi xes or fall under a particular Paramedic’s experience and suffi xes, that relates to the main idea and often skill level. describes the organ involved or the key symptom. Scored Adding a depression across the middle of a Rovsing’s sign Pain in the right lower quadrant that tablet that makes dividing the tablet in half easier. occurs when the left lower quadrant is palpated, Script An idea in the Paramedic’s mind about a set of which is often associated with appendicitis. symptoms that has an associated symptom complex Rub A low-pitched, soft scratching sound that occurs at and an associated fi eld diagnosis and treatment plan. any time during the cardiac cycle. Sedative Medications used to decrease a patient’s Rules out A deductive process in which the Paramedic level of consciousness, lessen irritability, decrease eliminates all explanations for the patient’s condition excitability, or cause muscular relaxation. that don’t match the symptoms, thereby leaving the Segment The space between ECG waves. correct diagnosis. Seldinger technique A catheter-over-the-wire Runaway infusions An out-of-control drip infusion technique used to cannulate the femoral vein. that results in the patient being overmedicated. Self-awareness Possessing a conscious understanding Running the line out The process of clearing of one’s life infl uences and prejudices. intravenous administration tubing of any air and Semantics The meanings of words. running fl uid freely from the end. Senescence A breakdown in the body’s ability to Run of ventricular tachycardia Nonsustained bursts monitor for organ system failure and to repair those of ectopic ventricular beats that occur three or four at organs, which is inherent in the concept of being a time. elderly. Glossary 823 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Senile dementia Altered mental status caused by patient is asked to bring her right knee to the chest irreversible damage to the brain that typically is as far as practical. This position provides optimal manifest over a long period of time (e.g., a series of access to the anus while minimally compromising the brain attacks, such as strokes). patient’s dignity. Sensitivity A measure of how often a medical fi eld test Simulcast The ability to interact with several gives a correct positive result. departments of an organization at once. Sepsis A toxic condition resulting from the spread of Single-blind study A research study in which the bacteria or its toxic products from a focus of infection. subjects do not know which group they are in, Septal hematoma A form of nasal trauma that results although the researcher does. in a bruise or bleeding. Sinoatrial node (SA) The initial portion of the Septic shock Condition in which the patient develops conduction system, located just beneath the a potentially serious drop in blood pressure from a epicardium on the posterior wall of the right atrium systemic infection in the blood. near to the end of the vena cava and at the junction Serial vital signs All vital signs taken after the of the sinus of Valsalva and the atria. baseline vital signs that are useful to illustrate trends Sinus bradycardia A sinus rhythm with a rate below in vital sign changes. 60 bpm, although most patients are not symptomatic Serotonin A neurotransmitter found primarily in the until the heart rate falls below 50 bpm. gastrointestinal tract that causes arterial and venous Sinus dysrhythmia An irregular heart rhythm constriction. characterized by alternating increases and decreases Serve In legal terms, to cause to be delivered, as in a in the heart rate. summons or other document. Sinus of Valsalva An area adjacent to the aortic valve Settlement A sum of money paid to the plaintiff in that creates a space between the aortic wall and each order to conclude a case without going through a trial. semilunar wall. Shams Ineffective devices used in research trials that Sinus tachycardia A sinus rhythm with a rate greater appear similar to the actual device in order to create than 100 bpm. blinding for the participants. Situs inversus A condition characterized by complete Shared decision making Collaborative medical reversal of all thoracoabdominal organs, such that practice in which the patient is seen as being they are positioned the mirror opposite of normal. interdependent with, rather than dependent on, Skip A radio wave transmission technique to overcome the Paramedic. In a shared decision-making model, the problem of obstacles to line of sight, in which the the patient is consulted about clinical decisions, high-frequency radio antenna is directed toward empowering her with current information about her the sky. The radio signal then rises until it strikes the state of health. ionosphere, a layer of atmosphere where the sun’s Shared practice The knowledge that both physicians ultraviolet rays ionize the gasses, and the signal is and Paramedics are responsible for the patient’s care. refl ected back to Earth. Shock–liver A form of liver failure. Sky wave A radio wave transmitted into the Shunting A displacement of blood volume to the core atmosphere for a return to Earth rather than being circulation. transmitted across land. Side effects Unintended reactions one may have to a Slander Situation in which defamatory lies about a medication in addition to its therapeutic effect, such person are told to others. as drowsiness or nausea. Slip-tip A syringe adaptor that simply slides inside the Sign Indication that appears during a physical needle hub. examination that suggests the cause of a disease or Small volume nebulizer (SVN) An alternative injury. platform for the delivery of inhaled medications in Sign-out An authentication measure in which the which the medication is suspended in a stream of air Paramedic writes the time, date, and initial after which is then smashed against a round surface in the the last entry. The sign-out indicates that the PCR SVN, creating micro-fi ne particles that are ideal for was written and completed by the person listed “in- inhalation. charge” at the time and date listed. SOAP notes One of the earliest standardized Simplex A radio system that only allows communication documentation formats, which contains subjective in one direction at a time, such as a walkie-talkie; the (S) information obtained from the patient or the simplest radio system. patient’s family, objective (O) information obtained Sim’s position A modifi ed left lateral position used during physical examination, an assessment (A) of the when administering medication rectally in which the patient’s problem, and a plan (P) for action. 824 Glossary Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Social norm A rule of conduct that regulates the Star of life The symbol of EMS as represented by six interaction between people but is not specifi c to one points: detection, reporting, response, on-scene care, individual. care in transit, and transfer to defi nitive care. Social space In the theory of proxemics, an area of Starling’s law A cardiac theory that states the heart’s relative safety where strangers can enter, with certain stroke volume increases in response to an increase in expectations of conduct. A dining room in a restaurant the volume of blood fi lling the heart (the end diastolic is an example of the use of social space. volume). The increased volume of blood stretches the Somatic pain Acute sharp, burning pain that often ventricular wall, causing cardiac muscle to contract arises from the skin, ligaments, muscle, fascia, bones, more forcefully. or joints. Unlike visceral pain, somatic pain can be Static Radio interference caused by unshielded localized to a specifi c area. electrical devices emitting 60 cycle interference, Spacer A device attached to a metered dose inhaler lightning in the atmosphere, bursts of radio waves that allows a more controlled inhalation of smaller, from sunspot activity, and even the spark plugs in an ideal-sized drug particles suspended in the vapor automobile. within the chamber than are possible with the Status asthmaticus Persistent bronchospasm that is metered dose inhaler alone. resistant to routine treatments. Special incident reports (SIR) Documentation Status epilepticus A condition of unremitting completed by the Paramedic that is not directly convulsions interspersed with brief instances of coma. related to patient care but is instead used for Statute A law enacted by legislation rather than administrative purposes or as a part of a court previous case decisions. proceeding. Statute of limitations The time allowed from the Specialty Care Transport (SCT) A growing occurrence of an incident during which a lawsuit can subspecialty in EMS, in which Paramedics perform be fi led. The statute of limitations simply states that critical care interfacility transportation by a plaintiff (usually the patient) cannot commence a transporting sick and injured patients from outlying lawsuit after a certain amount of time has passed. clinics and critical access hospitals to tertiary care Sternal notch An anatomical position near the base of centers. the neck. Specifi city A measure of how often a patient with a Sternal retractions Situation in which the work of negative medical fi eld test truly does not have the breathing increases and more effort is needed to condition the test is designed to detect. generate the negative pressure in the thorax required Spike Sometimes called a bayonet, a very sharp point for inspiration. When this happens, the skin at the on an administration set which is used to pierce the top of the sternum is pulled inward because of this fl uid container. negative pressure in the chest. Spirits Liquid medications brewed from various materials Stethoscope A medical instrument used to listen that have a volatile oil that evaporates at room inside the body, consisting of hollow fl exible tubes temperature and leaves a distinctive odor in the air. connected to ear pieces that join to a piece placed Spontaneous abortion Situation that occurs in about against the area to be evaluated. 30% of pregnancies in which the zygote fails to implant Stewardship To uphold the noble traditions of and the pregnancy prematurely ends; often referred medicine while caring for patients. to as a miscarriage. Stigma A negative connotation attached to Squelch control A static-reduction technique in participation in a program, such as labeling and public radio transmissions that reduces the amount of signal embarrassment. received between transmissions, narrowing the Stochastic effects Long-term complications from reception of radio waves and eliminating background ionizing radiation exposure. interference. Stock solution A standard concentration of a solution Standard leads The 12 leads used in a standard that may be diluted to weaken its potency for certain electrocardiogram, comprising the standard bipolar patients. limb leads I—III, the augmented unipolar limb leads, Strain Signs of fatigue often seen when the body is and the standard precordial leads. repeatedly overstimulated, perhaps by constant Standard of care Care and treatment that another bombardment by stress-inducing stimuli. Paramedic with the same or similar training would Stress The body’s reaction to stimuli; a disruption in have rendered in the same or a similar situation. homeostasis. Standing orders Preauthorized medical orders often

Stress management A process of coping with chronic given to Paramedics by physicians. stress in an effort to recover from its effects. Glossary 825 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Stress reduction Actions an individual takes to paraphrases the patient’s words to ensure that the eliminate the source of stress. message sent was correctly received. Stressors Stimuli that cause stress. Modern stressors Summary dismissal A request by the defendant’s include psychosocial pressures from family, coworker attorney to end a court action based upon the facts in complaints, and supervisors’ demands, as well as such the case, stating that the facts of the case are clear things as unrealistic expectations and noise pollution. and without dispute. Strike-out A method of error correction on the patient Summary judgment Determination by a judge to care report in which the Paramedic crosses through dismiss or decide a case solely on the preliminary the mistake with a single line, leaving the content evidence without conducting a trial. below the strike-out legible. Next to the strike-out, Support Assistance that promotes another’s interests. the Paramedic should place the date and initial the Suppositories Medication within a wax carrier that strike-out to indicate authorship. melts at body temperature and is typically given ST-segment depression A reduction of the ST internally for a local effect; often administered in the segment, which is a >1 mm depression below the vagina, urethra, or rectum. J point from isoelectric baseline. Supraventricular rhythm A cardiac rhythm ST-segment elevation A rise in the ST segment, originating above the ventricles, indicated by which is a >1 mm depression below the J point from a narrow QRS. isoelectric baseline. Surfactant A fl uid that decreases the alveoli’s surface Stylet A commonly used adjunct to oral intubation that tension and prevents the alveoli from collapsing during provides rigidity to the endotracheal tube. expiration. Subcutaneous emphysema The presence of air Surgical anesthesia A near-coma state of sedation between the layers of the skin that indicates a leak in in which the patient loses protective refl exes in the respiratory system. a head-to-toe (cephalocaudal) direction. Subcutaneous injection Injection in the layer of skin Surgical cricothyroidotomy A surgical procedure to directly below the dermis and epidermis, which is gain entry to the trachea through the anterior neck by the slowest and least dependable means of obtaining making an incision through the cricothyroid menbrane. therapeutic drug levels in the bloodstream. Suspension Medications that will not dissolve in a Subendocardial ischemia Condition that occurs solvent and thus remain as fi nely pulverized particles during myocardial ischemia in which the deep fl oating in a liquid. myocardial tissues becomes ischemic fi rst, since Sweep speed The speed of the rhythm passing by coronary perfusion occurs from the surface (or on the ECG monitor screen. Standard sweep speed epicardium) inwardly. is 25 mm/second, although the Paramedic may alter Subpoena A legal command or direction issued by the this speed to get a closer look at certain features of court to appear at a certain place, such as the offi ce an ECG. of the plaintiff’s attorney or the courthouse, at a Sympathetic nervous system The portion of the particular time. autonomic nervous system responsible for those Substituted judgment Situation in which a surrogate emergency responses that are at “stand-by,” ready decision maker has the responsibility to know the to provide the person with the ability to fl ee (fl ight) patient’s preferences and must place the patients’ or fi ght. wishes before the surrogate’s wishes. Sympathomimetics Drugs that mimic the effects of Succinylcholine A depolarizing neuromuscular the sympathetic neurotransmitter norepinephrine. blocker composed of two acetylcholine molecules Symptom Something that indicates the presence of a hooked back to back. It offers a rapid onset of physical disorder. action (30 to 60 seconds) and rapid termination of Symptom complex A list of abnormal conditions effect (3 to 12 minutes) with return of suffi cient found by the Paramedic during the history of the ventilation to sustain life in 8 to 10 minutes. present illness and the physical examination. Succinylcholine produces muscle fasiculations at Symptom pattern A series of conditions associated onset of action. with a known disease. The Paramedic compares the Suffi x An affi x placed at the end of the root word to symptom complex against the symptom pattern arrive modify that root word; for example, adding the suffi x at a diagnosis. “-less” to the root word “help” makes “helpless,” Synapse The point at which an impulse passes from meaning something different than “help.” one neuron to another. Summarization Communication technique in which Syncope A transient loss of consciousness that the Paramedic takes the patient’s own words, then spontaneously resolves. 826 Glossary Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Syndrome A collection of symptoms that characterize Teachable moment The time when the patient has a a condition or state. heightened awareness of a problem and is receptive to Synergism The interaction between drugs which can information. occasionally lead to unexpected or extra effects. Telemetry The process of transmitting measurements Syntax The rules of grammar. and recordings to another location, where they are Syrups Medicines mixed with sugar and water. interpreted; a monitoring device connected to a System architecture The arrangement of radio patient by two or three wires that collects data and components. Currently, two radio architectures sends it via radio waves to an antenna. exist in EMS: traditional land mobile radio (LMR) Teleological A model of ethics that simply states the architecture and cellular system architecture. end justifi es the means. This approach implies that, Systemic Pertaining to more than one internal organ even though some harm may occur, in the end if the system. outcome is good then the behavior is ethical. Systemic infl ammatory response syndrome 10-codes A system from the 1920s in which police (SIRS) Localized infection leading to systemic departments that only had one radio frequency used infection leading to sepsis, then on to septic shock and abbreviated messages designed to minimize airtime. multiple organ dysfunction syndrome. Plain speech is preferred over 10-codes to avoid Systemic pathology Illnesses and ailments of humans confusion and improve interoperability. related to specifi c organs. Tenderness A soft or yielding texture; physically Systems review A head-to-toe approach to history weak. gathering in which the healthcare provider starts Tentative fi eld diagnosis A determination of what’s at the head, questioning about issues/concerns causing the patient’s problems performed upon initial that may be present at the nervous system level evaluation. (stroke, seizures), and moving downward to cover the Teratogen Toxic substance or agent such as an illegal cardiovascular system, respiratory system, abdomen, drug or an infection such as rubella (measles) or genitourinary system, extremities, and behavioral toxoplasmosis that could lead to fetal malformation. disorders. Teratogenic effect Exposure to ionizing radiation System status management (SSM) A dynamic that can cause birth defects and cancer in subsequent alternative to fi xed-post staffi ng in which ambulances generations as a result of changes in the structure of are “on the road” and moving to new locations to DNA. improve response times. Tertiary care Highly specialized care provided in areas Systole Ventricular contraction. such as trauma centers and cardiac centers. Systolic blood pressure The maximum blood Therapeutic effect See Intended biological effect. pressure measured during systole when the heart Therapeutic index The ratio of the difference contracts. between a drug’s median effective dose (the ED50) Tablet A dry medicinal powder that is compressed into and the median lethal dose (the LD50). a pill shape. Therapeutic level (t) The point when the drug Tachycardia A heart rate that is over 100 beats per levels attain the targeted value, as manifested by minute for an adult or above the upper limit of normal observation of the therapeutic effect. for a child. Therapeutic touch Intentional touching that mimics Tachypnea Rapid breathing. earlier comfort experiences (such as a mother stroking Tactical EMS (TEMS) EMS providers working with an infant’s cheek) and telegraphs reassurance, police SWAT teams trained on how to provide care understanding, and caring to the patient as a means to to the wounded while in hostile surroundings as well heal. as maintain the health of the SWAT team members Third spacing A process that occurs when colloidal during prolonged operations. osmotic pressure is low, in which fl uid leaks from the Tactile fremitus Vibrations palpated on the chest wall intravascular space and into the interstitial space. that occur with speech. 3-3-2 rule A simple method for rapidly evaluating a Tamponade Compression performed to control patient’s anatomy, in which a Paramedic should be bleeding. able to place three fi ngers between the tip of the chin Tardive dyskinesia A neurological disorder and the hyoid bone, place three fi ngers between the characterized by involuntary movements of the upper and lower teeth at the maximal mouth opening, extremities often caused by long-term use of certain and place two fi ngers between the thyroid notch and drugs (antipsychotic or neuroleptic). the fl oor of the mouth. Glossary 827 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Thrill Vibration of the chest associated with heart Transfusion-associated circulatory overload contraction. (TACO) Situation that occurs when the patient Thrombin A protease in blood that facilitates blood receives more volume of blood products than can be clotting by converting fi brinogen to fi brin. handled by the circulatory system. Thrombocytes Platelets; blood cells that aid in Transfusion-related acute lung injury (TRALI) clotting. A new acute lung injury that occurs within six Thrombophlebitis An infl ammation of a vein that may hours of a transfusion and is directly related to the develop at an IV insertion site. transfusion. Thrombus A mature clot made of platelets cross-linked Translaryngeal illumination Using a lighted stylet with fi brin and other blood cells in a fi rm meshwork; a during endotracheal intubation to take advantage of blood clot. the larynx’s proximity to the anterior surface of the Thyroid gland A highly vascular, “H” shaped structure neck. that lies along the sides of the larynx and upper Translocations Gross breaks in some chromosomes trachea. with subsequent rejoinings at new locations. Tidal volume The volume of a normal breath, Transmission The process of conveying a approximately 5 to 7 cc/kg of ideal body weight. message, which can be either a true and accurate Tincture Medicinal substance that is dissolved in representation of the sender’s thoughts or may alcohol. be conveyed in such a way that the meaning is Tincture of benzoin Medication often applied to skin misconstrued by the receiver. before applying tape or another adhesive bandage, Transmural ischemia The stage of myocardial used to both prevent allergic reactions on the skin ischemia when the ischemia affects the entire from the bandage and to help the tape or bandage thickness of the myocardium, from the endocardium adhere longer. to the epicardium. To keep open (TKO) The minimal infusion rate Transtracheal jet ventilation (TTJV) Ventilation needed to keep veins from becoming occluded by a of the lungs using special high-pressure devices clot. through a large bore catheter placed through the Tolerance Resistance to a drug over time, which cricothyroid membrane, which is a commonly taught prompts the patient to take larger doses of the drug and performed

emergent oxygenation technique. to acquire the same effect. Trauma Mechanical injury due to abrupt and sudden Tonic A series of whole body contractions that often physical forces acting upon the body, such as friction, precede a seizure. blunt force, or penetrating force. Tonicity A solution’s ability to exert an osmotic Trauma line Intravenous access inserted into the pressure upon the membrane. vascular space so that intravascular volume can be Topical Medications meant to be applied to the skin. replaced quickly. Tort A civil or private wrongful act, other than a breach Treatment pathway The continuum of patient care of contract, resulting in some type of injury or harm which starts with the primary assessment and is (not necessarily physical injury). continued in the emergency department, critical care Total body clearance The sum of all drug excretion units, rehabilitation fl oors, and homecare services. from the kidneys, skin, lungs, and liver. Triage tag A form of documentation tag used in mass Toxicology The study of poisonous substances. casualty incidents to quickly prioritize patients based Toxin Any substance capable of causing cell injury and on how quickly they need assistance (i.e., immediate death, including poisons. treatment vs minor injury). Trace A horizontal left-to-right movement on an ECG Trigeminy Situation in which ectopic complexes occur monitor. every third complex. Trachea A conduit for respiratory gasses to pass to and Tripod position A position patients may assume from the lungs. when in respiratory distress to help with breathing, Tracheobronchial suctioning Direct suctioning of in which they place their hands on their knees or the secretions in the bronchial tree. legs and lean forward in a sitting position, creating a Trade name Drug name manufacturers give a tripod. This position allows the overworked accessory patented drug to distinguish it from other similar muscles to work better, although most patients begin drugs. to tire when they are in such severe respiratory Transdermal Pertaining to topical medication distress. absorption, in which medicines are applied to the skin Troches Lozenges that dissolve and are absorbed in the and absorbed into the body. mouth through the oral mucosa. 828 Glossary Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Trunking A technique whereby, using computers, assessment and evaluation is needed before treatment multiple users can communicate over fewer is initiated. frequencies, with the computer selecting the Use- (rate) dependent Drugs which act upon the frequency to be used based on availability. ionic channels during the open/active state and Turgor A distended state of tension in living cells. preferentially will be attracted to rapidly depolarizing Turned over to A process of transferring a patient to ectopic pacemakers. another care provider with equal or greater skill. Uvula A fl eshy lobe that typically hangs in the midline Tympanic membrane Sometimes called the eardrum, of the pharynx. a thin membrane that separates the external ear from Vagus nerve The major parasympathetic nerve which the middle ear. originates in the medulla, exits the skull at the base Type and crossed Donor blood that is successfully of the brain, travels down the neck (proximal to the matched to recipient blood. larynx), branches into the heart and lungs, innervates Type and cross-matched See Type and crossed the stomach, passes through the digestive tract, and Type I error A common error made in an experiment in ends in the anus. which the researcher rejects the null hypothesis and Valecula The space formed between the anterior- accepts the alternative hypothesis when in fact it is superior surface of the epiglottis and the posterior not supported. base of the tongue. Type II error A common error made in an experiment Valid Logically correct and accurate. in which the researcher incorrectly fails to reject Value judgment A Paramedic’s decision as to which the null hypothesis; a failure to observe the change course of action is the correct course of action in created by the treatment when one did occur. terms of right or wrong. Umbilical cord A connection between the mother’s Vapocoolant spray See Fluori-methane. placenta and unborn child (at the navel) used to Vasopressor A chemical that causes vasoconstriction, transfer nutrition, respiratory gasses, and wastes in particularly on the arterioles. the months prior to the child’s birth. Vastus lateralis (VL) An intramuscular injection site Unilateral Relating to only one side. on the anterior thigh. The Paramedic mentally divides Unipolar lead The use of a single positive electrode, the vastus lateralis muscle into three equal portions. using Wilson’s central terminal, to record differences Choosing the middle section of the VL, the Paramedic in electrical potential. prepares the intended injection site with an alcohol- United States Pharmacopeia (USP) A drug reference soaked pad. created by an independent nongovernmental science- Vector The sum of electrical events which makes up based public health organization called the United the common direction of the electrical wave front. States Pharmacopeia. The United States Pharmacopeia Vecuronium A non-depolarizing neuromuscular is made up of over 1,000 scientists, practitioners, and blocking agent commonly used by Paramedics in the representatives from various colleges of medicine and prehospital setting. pharmacy who set the standards for medication Venous cannulation The process of threading a manufacturing in the United States. catheter into a vein. Universal donor Name given to Type O blood, since it Ventilation A measure of how well a patient is moving can be given to any of the A-B-O blood types without air in and out of the lungs during inhalation and adverse reactions. Type O blood does not have surface exhalation. proteins that incite the immune response, which ends Ventricular diastole Condition after a contraction in hemolysis. when the ventricles of the heart are in a relaxed state. Universal law A situation that demands action by any Ventricular rhythms A heartbeat originating from person in that situation, as a matter of duty. the ventricle, indicated by a wide QRS. This is Universal recipients Name given to individuals with usually, but not always, dangerous because the Type AB blood, since they can receive blood from any origin of the beat is in the last pacemaker in the donor. This is because people with Type AB blood do ventricles. not have antibodies against A or B proteins present in Ventricular systole Condition in which, with the the plasma. pressure elevated in the ventricles, the ventricular Upregulation An increase in the number of cell muscle fi bers contract forcefully and generate receptors in a body cell due to changes in chemical suffi cient pressure to force open the aortic and levels. pulmonary valves to eject blood out of the heart. Urgent An assessment classifi cation in which the Ventricular tachycardia A rhythm experienced when patient’s condition is not emergent, suggesting further the ectopic focus is ventricular and the ventricular Glossary 829 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. pacemaker becomes dominant. With ventricular Vital signs Objectively measured characteristics of tachycardia, the rhythm is regular, the rate is fast, basic body functions, such as temperature, pulse, and every beat is wide. respirations, and blood pressure. Vital signs provide Ventrogluteal (VG) An intramuscular injection site the Paramedic with an indication as to how well the located on the lateral thigh proximal to the hip. patient’s body is functioning or compensating for an Venturi masks Special masks with a restricted intake injury or illness. that permits an exact percentage of oxygen. These Volume overload A potentially devastating can be used to deliver oxygen, although their use in complication of intravenous infusions that occurs the prehospital environment is generally limited to when a positional IV access is inadvertently adjusted specialty care services. and the infusion fl ow is unrestricted. Veracity An adherence to truthfulness. When a Paramedic V/Q mismatch A mismatch between the amount of practices being truthful with all of her patients, then the lungs that are fi lled (alveolar ventilation) and the that Paramedic can be said to have veracity. capillary circulation (pulmonary perfusion). Verbal consent A spoken request for permission Walked on Suppression of a radio signal. to perform a procedure, accompanied by a simple Wellness A state of physiologic equilibrium free of explanation, which can improve patient compliance disease. More than an absence of illness, it is an and decrease the risk of misunderstanding. active process of becoming aware of, and making Vertical equity Injury prevention programs where the choices toward, a more successful existence. people most affected receive the major emphasis. For Wide open (WO) A rapid infusion of intravenous example, if statistics demonstrate a higher number fl uid. of accidental shootings among children in low-income Wilderness EMT (WEMT) An EMS provider in rural households, then public health programs could be and woodland areas with special training that fosters justifi ably organized to emphasize prevention within critical thinking as well as creativity when working in that population. an environment where supplies may be limited and Vesicular sounds Lung sounds auscultated over the patient transport to defi nitive care prolonged. peripheral, smaller airways that sound like leaves Witness A person who can confi rm testimony or rustling in the wind. evidence presented in a case, or authenticate Vicarious liability Based on the legal principle information provided. respondeat superior (“let the master answer”), the Working diagnosis A presumptive conclusion the basis that a person is accountable for the actions of Paramedic makes based on the available signs and others. symptoms. Virtue ethics A somewhat middle ground approach to World Health Organization (WHO) The most ethics that does not depend on consequence-driven prominent and infl uential international public health decisions or duty-driven decision making, but upon agency. virtues. The virtue ethics approach suggests that a Z-track An injection technique in which the Paramedic “right-thinking” person will make the best decision for holds the drug-fi lled syringe in the dominant hand, the patient based upon a predetermined set of virtues. bevel up, and pulls gentle traction on the injection Visceral pain Poorly localized pain that arises from site with the nondominant hand as a means to prevent the internal organs and is usually described as leakage. pressure-like, dull, or aching. Zygote A fertilized ovum. 830 Glossary Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. 9-1-1, 28 acetaminophen, 180–181, 690, adrenocorticotropic hormone 693–694 (ACTH), 166 A acetylcholine, 164, 479, 639 adulthood, developmental stage, abandonment, patient, 86 acetylcholinesterase, 479 144–149 abbreviations, medical terminology, acetylsalicylic acid, 498 adult respiratory distress syndrome 205–207 acid-base balance, 192–193, 495–500 (ARDS), 191 abbreviations, prescription acid load, 158, 192, 495, 497 Advanced Cardiac Life Support notations, 618 acidosis, 494, 497–499 (ACLS), 180 ABC system, shock assessment, acinus, 360 advanced directives, 78, 96–97, 149 192–193 acknowledging, patient responses, advanced emergency medical abdomen 236–237 technician (AEMT), 26 abdominal pain, assessment of, ACLS (Advanced Cardiac Life advanced life support (ALS), 279–281, 282 Support), 180 documentation, 345–346 chest pain, assessment of, 277 action potential, 655–656 adverse drug reactions, 630–631 distention, 258, 280, 410 active listening skills, 231 advice, offering, 237 fever, assessment of, 295–296 active transport, drug advocacy, patient, 11 palpation of, 259–260, 261 metabolism, 625 Advocates for EMS, 6 patient history, surgical, 344 activities of daily living (ADL), 99, AEIOU-TIPS, 248 physical exam, 258 147 aerobic metabolism, 159–160 pregnancy, assessment of, act-utilitarianism, 73 affi davit, 88, 347 296–297 acute coronary syndrome (ACS), African Americans, 61, 177 quadrants and nines, 281

Table of Contents Title Page Copyright Page PREFACE Acknowledgements CHAPTER 1 - THE EVOLUTION OF THE HUMAN RUNNER Evolution of Running Physiology of Runners The Future of Running CHAPTER 2 - CARDIOVASCULAR AND CARDIORESPIRATORY COMPONENTS Cardiovascular and Cardiorespiratory Systems Performance Training Progression CHAPTER 3 - THE RUNNER IN MOTION Running Gait Cycle ABC Running Drills CHAPTER 4 - ADAPTATIONS FOR FOR SPEED AND TERRAIN Event-Specific Body Characteristics Effects of Terrain and Other External Factors CHAPTER 5 - UPPER TORSO Choosing Resistance Repetitions Breathing Schedule CHAPTER 6 - ARMS AND SHOULDERS Specific Training Guidelines CHAPTER 7 - CORE Specific Training Guidelines CHAPTER 8 - UPPER LEGS Specific Training Guidelines CHAPTER 9 - LOWER LEGS AND FEET Specific Training Guidelines CHAPTER 10 - COMMON RUNNING INJURIES Specific Training Guidelines CHAPTER 11 - ANATOMY OF RUNNING FOOTWEAR Why Wear Running Shoes? History of 20th-Century Running Shoes Components of Running Shoes Barefoot Running Summary CHAPTER 12 - FULL-BODY CONDITIONING Water Running Plyometrics EXERCISE FINDER ABOUT THE AUTHORS Library of Congress Cataloging-in-Publication Data Puleo, Joe. Running anatomy / Joe Puleo, Patrick Milroy. p. cm. ISBN-13: 978-0-7360-8230-3 (soft cover) ISBN-10: 978-0-736-09183-1 (soft cover) 1. Running--Training. 2. Running--Physiological aspects. 3. Running injuries--Prevention. 4. Sports medicine. I. Milroy, Patrick. II.Title. GV1061.5.P85 2010 796.42--dc22 2009035764 ISBN-10: 978-0-736-09183-1 (print) ISBN-13: 978-0-7360-8230-3 (print) Copyright © 2010 by Joe Puleo and Patrick Milroy All rights reserved. Except for use in a review, the reproduction or utilization of this work in any form or by any electronic, mechanical, or other means, now known or hereafter invented, including xerography, photocopying, and recording, and in any information storage and retrieval system, is forbidden without the written permission of the publisher. This publication is written and published to provide accurate and authoritative information relevant to the subject matter presented. It is published and sold with the understanding that the author and publisher are not engaged in rendering legal, medical, or other professional services by reason of their authorship or publication of this work. If medical or other expert assistance is required, the services of a competent professional person should be sought. Acquisitions Editor: Laurel Plotzke; Developmental Editors: Mandy Eastin-Allen and Cynthia McEntire; Assistant Editor: Laura Podeschi; Copyeditor: Anne Rogers; Graphic Designer: Fred Starbird; Graphic Artist: Tara Welsch; Cover Designer: Keith Blomberg; Photographer (for illustration references): Neil Bernstein; Photo Asset Manager: Laura Fitch; Visual Production Assistant: Joyce Brumfield; Art Manager: Kelly Hendren; Associate Art Manager: Alan L. Wilborn; Illustrator (cover): Jennifer Gibas; Illustrators (interior): Precision Graphics and Jennifer Gibas; Printer: United Graphics Human Kinetics books are available at special discounts for bulk purchase. Special editions or book excerpts can also be created to specification. For details, contact the Special Sales Manager at Human Kinetics. Printed in the United States of America 10 9 8 7 6 5 4 3 2 1 The paper in this book is certified under a sustainable forestry program. Human Kinetics Web site: www.HumanKinetics.com United States: Human Kinetics P.O. Box 5076 Champaign, IL 61825-5076 800-747-4457 e-mail: humank@hkusa.com Canada: Human Kinetics 475 Devonshire Road Unit 100 Windsor, ON N8Y 2L5 800-465-7301 (in Canada only) e-mail: info@hkcanada.com Australia: Human Kinetics 57A Price Avenue Lower Mitcham, South Australia 5062 08 8372 0999 e-mail: info@hkaustralia.com New Zealand: Human Kinetics P.O. Box 80 Torrens Park, South Australia 5062 0800 222 062 e-mail: info@hknewzealand.com Europe: Human Kinetics 107 Bradford Road Stanningley Leeds LS28 6AT, United Kingdom +44 (0) 113 255 5665 e-mail: hk@hkeurope.com E4782 PREFACE Beginning with a chapter on the evolution of the human runner, Running Anatomy endeavors to educate runners about how and why their bodies work as they do during the movements of running. Running Anatomy explains not only how the soft tissues and bones interact to produce movement, but why they do so and what you can do to maximize your own personal running goals. By detailing the mechanisms of movement through illustrations, we hope to show, in a simple format, what happens when your body engages in running. The goal of this book is threefold. First, the illustrations in this book are meant to aid the runner in understanding the anatomy impacted when the runner is in motion. By calling out the anatomy associated with the running motion, we hope to further the runner’s understanding of how bones, organs, muscles, ligaments, and tendons work to move the body. The anatomical illustrations that accompany the exercises are color-coded to indicate the primary and secondary muscles and connective tissues featured in each exercise and running-specific movement. Then, after detailing the hows and whys of running, we focus on the significance of strengthening your body through strength training devised for performance enhancement. The text in each chapter further explains the function of the anatomy shown in the illustrations. Finally, the strengthening exercises included in each chapter will improve running performance and help to keep the runner injury-free by eliminating anatomical imbalances that often occur naturally but are exacerbated by the muscular-skeletal demands of running. The ultimate goal is to create a strength-training program that is logical and easy-to-use but also effective in improving running performance. Since injuries often occur as a result of repetitive movement, understanding how and why the body moves may be a simple way to enhance performance and prevent injury. Our intent is to enhance your running experience and performance by helping you understand the anatomy of running and develop a clearly defined strength-training program. ACKNOWLEDGMENTS Many people contributed to this book in many different ways. Jack Kraynak, Jay Carlin, Rob Weinmann, Dale Luy, Ken Deangelo, and Bill Preston were my coaches and mentors. Bob Kirkner, Dr. Carolyn Peel, Bill Bender, Scott Conary, Dave Salmon, Cassy Bradley, Abby Dean, Jay Johns, Sean Mick, Patty Deroian, Terry Luzader, Dave Welsh, Chris Ganter, Suzanne Dorrell, Sharon Smith, Jay Friedman, Mike Fox, Travis Stewart, Frank Iwanicki, and Robin England were training partners and guinea pigs. Capt. David Litkenhus, Lt. Col. Steven Peterson, Dr. Gregory Ng, Brian Walton, Harvey Newton, Bran-don Risser, Myrna Marcus, Bob Gamberg, Bob Schwelm, Todd Williams, Dave Shelburne, Paul Slaymaker, Steve Dinote, Graig White, the members and staff of the Rutgers University-Camden track and field team, and the Haddonfield Running Company provided professional support and friendship. Models Brandee Neiderhofer, Jon Salamon, Lyndi Puleo, Anthony Witter, and Jorge Ramos gave their time and talents to make the illustrations possible. The Spa Fitness Center in Pennsuaken, New Jersey, and owner Tom Loperfido allowed us to shoot the reference photos. The staff at Human Kinetics—Laurel Plotzke, Leigh Keylock, Mandy Eastin-Allen, Laura Podeschi, Neil Bernstein, Jen Gibas, and Cynthia McEntire—guided the publication process. Special thanks to my wife, Lyndi, and children, Gabe, Anna, and Sophia, for sharing me with this project for the past two years. Also, my efforts are in honor of my grandfather Joseph A. Puleo, Sr., and my father, Joseph A. Puleo, Jr. Joe Puleo My writing skills were developed through the advice of various editors of Runners World (UK), for whom I was medical adviser for 25 years, and the help and encouragement of the staff at Human Kinetics, without whom this project would never have got off the ground. I could not have completed this project without the love and understanding of my wife, Clare, and the support of my family and friends, many from the running world. Dr. Patrick Milroy CHAPTER 1 THE EVOLUTION OF THE HUMAN RUNNER Haile Gebrselassie once said, “Without running there is no life.” The sheer joy expressed by Gebrselassie about his running is shared by millions around the globe. It surpasses language and cultural barriers, so a stranger abroad can invariably change into shorts and running shoes, find a trail, and meet kindred spirits enjoying life with the same enthusiasm. Running ranks highly among ways of combining pleasure with health promotion. As civilization has progressed, the need for people to run for survival has been tempered by the development of new skills so that the average human can now enjoy leisure time in a way that the majority of our ancestors would have found at the very least impractical, and quite possibly fatal. Although the ability to run was once quite literally a matter of life and death, the social development of the biped means that running has taken on a new character. It has become a conduit for the expression of human competition, of socialization, and of scientific experiment and development. It is probably the most natural form of exercise that does not involve aggressive or antisocial techniques or require expensive equipment. Any able-bodied human should be able to enjoy it. Although the first purpose of this book is to enable you to understand the function of the anatomy of the body involved in running, the greater aim is to add training exercises and techniques that any runner can use to enhance his or her own sporting satisfaction. Running better does not necessarily involve running faster. If this book allows you to complete your runs in a more relaxed and less distressed manner than previously, and if following the exercise schedules reduces the incidence of pain and injury, then that is surely a positive gain. Not only will you be able to look back on your previous run with pleasure, but the anticipation of the next is likely to be far more positive as well. In the past 40 years, an entire industry has developed around the sport, although the practice of running stretches back for many thousands of years. Clothing and shoes, diet and physiology, and the surfaces on which and the environment in which we run have all undergone research, experimentation, and review in this short epoch. In much the same way that the coming of the “Iron Road” of railways some 200 years ago changed the way in which we lived, so running has entered the everyday lives of millions of people and with very few exceptions has benefited the majority. Although it is impossible to completely ignore the other interlinked factors that make a runner what he or she is, this chapter traces the evolution of anatomy as it affects the runner, researches the characteristics and physique that produce success, and even tries to predict the makeup of the perfect runner, if such an individual could ever exist. In the past, many learned authors have speculated on the ultimate running performance, only to find it bettered. We would like to envisage the makeup of the athlete who could produce that unbreakable record, and then in the subsequent chapters guide you toward making and breaking that goal. Evolution of Running The running skills of humans evolved as a response to predators who also vied with humans for sustenance. This was before our brains developed and we were able to think our way out of trouble. Those who could run the fastest not only got to the food first and had the biggest and most nutritious portions, but also were able to leave the quickest if danger appeared. Those who were unable to run were invariably the first to fall by the wayside because of an inability to obtain sufficient food, or because they lacked time to eat it, or because they fell victim to predators as a result of their lack of mobility. It might be interesting to conjecture how fast our predecessors would have been able to run if they had not developed their brains and learned more cunning ways to avoid danger. However, the concurrent use of brain skills to manufacture weapons with which to hunt meant that our forebears had to rely less on pure speed for survival, and the ability to run flat out became less of a necessity and more of a virtue. The communities in those times were largely tribal, and chiefs had skills over and above the majority, so the ability to run fast would figure strongly as he or she sought respect, much of which could be gained through competition, which could include running races. Eventually, the survivors passed on the genetic makeup that produced speedy legs to their offspring, and because the need to be able to run at speed was still required, faster runners continued to evolve. In those times, pure upper-body strength was generally needed more than litheness, so those peoples for whom running had become a less important element of their life skills would probably not have looked much

like competitive runners as we see them today (figure 1.1). These were people who spent their lives in physical endeavor, so they probably had a physique equivalent to the modern gym attendee, who regularly works out on a broad program of exercises but avoids specific sport-related repetition. At some time, running evolved to have other uses. Although horses were the principal carriers of messages, sometimes people could be more efficient. Some 2,500 years ago, Pheidippides ran from Marathon to Athens to deliver news of victory in battle against the invading Persian army, though he did little to promote it as a leisure activity, dropping dead as he finished the run. Today, people and horses have an annual organized race in Wales to test the theory about which is the faster species. These early civilizations were able to enjoy sports, and one development was the organized Olympic Games, which honored the Greek gods and included running races over various distances. They lasted until AD 394 but were eventually banned because of their pagan origins. Until relatively recent times, women did not run anywhere near as much as men, partly because they were not participating in the same kinds of foraging and defense activities; rather, they were expected to produce children, usually the more the better and one after another. Time was then used to feed and teach these offspring the basic skills needed for survival until the mature males took over for the more advanced tutoring. The ability to run might still have been necessary to avoid danger, although advances in methods of transportation would have lessened the need even for this. Figure 1.1 Comparing the physical build of (a) a runner from the past with (b) a contemporary runner. Hard evidence of both competitive and noncompetitive running between Roman times and the Middle Ages is hard to come by. It may well have happened, but it was not recorded by the scribes of the time who had far more important items to chronicle, so it has become lost in the mists of history. Once they had established the basics for living, people from those times were more concerned with territorial gain and religion than events that would have done little to enhance their lives. If any time was given to leisure pursuit, running would have had to compete with throwing and wrestling events, weapon skills, and the inevitable drinking competitions, among many others. Some 14th-century texts contain references to running races held across open country, and there is evidence to suggest that competition developed from games based on hunting. In the 18th century, a new sport had emerged in which two or more horse riders would race each other to a distant church steeple. By the 19th century, simple foot races called steeplechases were organized along the same lines. These races were promoted further by the fee- paying schools and universities in the United Kingdom, who also ran “paper chases” in which a “hare” would leave a trail of paper for the “hounds” to follow. This led to the formation of the amateur Harrier Clubs for road and cross-country running that still exist today. Once again women played no part in this social convention, decreeing that it was inappropriate and demeaning to the upper classes, and the poorer majority were far too busy simply trying to survive. During the second half of the 18th century, walking competitions between gentlemen’s servants gave way to men racing against time over longer distances. One of the more popular goals involved covering at least 100 miles in less than 24 hours. Those who achieve this are still called centurions in a flashback to Roman times. Other contests involved covering one mile in each of 1,000 successive hours. (This is more than 40 straight days!) The early 19th century saw the return of races between men, and town-to-town events, accompanied by heavy gambling, for a while became the most popular sport in England. The winners of these races were those who adapted to the generally horrific environmental circumstances and lack of nutritional variety that existed at the time. Disease was rife, life expectancy was short, and diet relied in the main on whatever seasonal local supplies were available. Any training for the events as recognized in the 21st century was nonexistent, and the pedestrians would consume large quantities of meat, often raw, and alcohol, frequently in large quantities, before and during competition. In fact, training specifically for a race was considered to hinder performance because it might exhaust their energies. It was not that they were unfit, as the competitors invariably came from the laboring masses for whom a 12-hour day of physical toil was the norm, rather than from the much smaller ranks of those with sedentary jobs. The establishment of the modern Olympic Games was of little interest to the majority of the world’s population, who had no means of entering or enjoying competition, even if they knew of it; until well into the 20th century, the Games remained the prerogative of the rich and otherwise idle, who disdained most preparation for the events. Some pioneers such as Paavo Nurmi and Hannes Kolehmainen put thought into how their racing performances could be improved and utilized the most basic sport science, but it was only in the second half of the 20th century that disciplines that could be recognized as scientific were applied to running, such as those done by Arthur Lydiard. Lydiard was different: He trained alongside his protégés, asking them to do no more or fewer miles than he, and led them through a regime that intrigued the world. It was LSD—long slow distance—for everyone. Percy Cerutty used new techniques including sandhill running to win his students Olympic gold medals. Running and science have had a symbiotic relationship because runners have become unintentional guinea pigs for physiological testing. When statistics have demonstrated that runners have veered away from some expected normal values, scientists have been able to use the results to explain the physiology of the heart, circulation, lungs, and other organs. Extrapolation of the findings has led to progress in many medical specialities. Intertwined with this have been the advances in dietary knowledge. In basic terms it might prevent a runner from the consequences of eating a large meal before exercise, and at its most sophisticated, elite athletes often have an integral dietary program prepared as part of a whole season of competition. Medicine could never have developed to the extent it has without the participation of the running community any more than runners could have become faster without sport science. Running hit the headlines as a leisure activity for the general populace only after the mass publicity and television coverage that accompanied the New York and London marathons in the late 1970s. In these races there was a large number of newcomers to the sport in which the emphasis on speed was replaced by jogging at little more than walking pace. It would be an exaggeration to call the majority of them competitors. This development was not only tolerated but also even encouraged as the races became a mixture between the opportunity to raise money for charitable causes and fancy dress competitions. In terms of speed, the successful runners were those who had prepared themselves best both physically and mentally. It was noted that faster runners rarely carried excess weight, and the perception of running as a health benefit grew as parallel advances in science demonstrated that obese and sedentary people had a lower life expectancy. Race winners had usually run many miles in training before competition, although grossly excessive mileage, as in the case of British 10,000-meter world-record holder Dave Bedford, could lead to painful and career-ending injuries. It became understood that running well was not simply about quantity, but the quality of the mileage was also a decisive factor, so multiple theories of optimal training regimes abounded, none of which has yet been shown to be superior to the others in all circumstances. Physiology of Runners As more nations entered competition, ethnic variations in ability appeared. Afro-Caribbean athletes showed themselves to be the preeminent sprinters, whereas those from higher altitudes became the fastest endurance athletes, their bodies having adapted to a decreased oxygen concentration in inhaled air. The act of sprinting fast uses nearly all the muscles of the body during the event. A still photograph of the top exponents at full speed will show taut neck muscles and bulging eyeballs, not exactly the first areas to be considered when running! But if these muscles, in whatever small way, are used to increase speed, then these muscles must be trained for the event in exactly the same way as the massive thighs that provide the explosive power and high knee lift more usually associated with sprinting. Conversely, the best long-distance runners became almost pitifully thin, especially in the largely underused upper limbs, as it was realized that the less weight that they carried, the less energy would be expended in moving their bodies efficiently for mile after mile. However, one enemy of the distance runner is dehydration, a catalyst for both illness and injury, so adaptation to conserve and absorb water, especially in warmer climates, was at odds with the perceived need to be emaciated. Low fat stores, thin and sinewy muscles, and a low mass of other soft body tissues are not conducive to transporting large volumes of fluid internally during a run. The core temperature of the body needs to remain as close as possible to 98.6 degrees F (37 degrees C), not only to work most efficiently, but also, and more important, to survive. The energy burned when running produces heat, and it is by the mechanism of sweating that the core temperature is maintained. If the body is dehydrated, this cannot occur, so at worst a life-threatening hyperthermia may develop as the body temperature rapidly soars. This may help to explain why some winners of distance races can be comparatively well built, because they are able to store larger quantities of fluid to provide for the event. Science shows that performance deteriorates precipitously as the runner becomes overheated and dehydrated, so as with the tortoise and the hare, the winner may be the runner who has prepared best for the whole distance and not relied on pure speed to win the day. Transposing the body types and events quickly demonstrates the impracticality of either entering the other’s competition. The sprinter would quickly tire as he carried his comparatively heavy body for more than a few hundred meters, even if he could store sufficient fluid, whereas the undermuscled distance runner would immediately be at a disadvantage in an event requiring brute strength and power. These are extreme examples, but in general most events attract successful competitors who have comparatively similar physiques. It is interesting to consider how rare it is that more than one world record is held by a single competitor; where it is, the events tend to require very similar speeds and skills. Thus, Michael Johnson simultaneously held the 200- and 400-meter records, and Haile Gebrselassie the 5K and 10K, but for success at the highest level, the Olympics and world championships, very few runners enjoy the luxury of being able to prepare for, let alone win, more than one event. Women have been latecomers to the running scene. Races for women longer than 400 meters were not introduced to the Olympic Games until 1964 because it was considered, without any scientific proof, that they might suffer some unspoken medical ailment if they were to “strain” themselves. Once it was shown that they thrived in competition, their advancement was so rapid that by 1984 they were allowed their very own marathon at the Los Angeles Olympics. Anatomically, women are generally disadvantaged compared to their male counterparts (compare figures 1.2 and 1.3), especially where the long, light levers that make up the lower limbs are concerned, but physiologically they are in some ways better prepared, especially for ultradistance running. Because they have proportionately more fat as a percentage of body weight compared to their male counterparts, they have greater reserves of energy and stored fluid to call on, although it may take days rather than hours of competition for this to emerge.

It is in ultradistance racing that the performance of women comes closest to men. With increasing distance, the difference between the sexes in statistical terms in time run becomes less and less marked, so it may well be that one day a woman will win an open race purely as a result of better physiological efficiency. Women are disadvantaged by relatively short thighs, which become exaggerated by their wider hips and bring the pelvis closer to the ground, resulting in a reduction of stride length. Stride length is perhaps the factor with the most effect on the speed of running. Although the fastest runners take no more than double the number of strides of the slowest over a given unit of time, their stride length may be up to four times greater. Although the abdomen of the male largely consists of the intestinal organs, which are involved in fluid balance and retention, that of the woman also has to accommodate the relatively bulky uterus and reproductive organs, limiting the volume available for the bowels. These are not large differences, perhaps even only 1 percent or 2 percent, but they also determine the differences between the relative athletic performances of the two sexes. Add to that breasts and the limitation of smaller chests and lung capacity, as well as smaller feet, which mean that part of the mechanical leverage of propulsion is reduced, further handicapping women when pure speed is the consideration. However, as the male distance runners have shown, small size is not necessarily a disadvantage, and the physiological differences that become more marked in favor of women with greater time and distance run may ultimately lead to an equalization between the sexes over the longest distances. Figure 1.2 Male runner: (a) front view; (b) side view. Figure 1.3 Female runner: (a) front view; (b) side view. Once the genetic core of the body has been established, there is only so much that each individual can do to develop his or her physique as a running machine. Even if one discounts artificial aids to body shaping, such as liposuction or steroid drugs, there are certain limits to the adaptation of the adult human form. No mature adult can lose or gain height voluntarily, and exercise training and dieting will only change or mature physique within the limits of capacity, such that although muscles develop as a result of exercise, there are individual limits to the amount of exercise that any single person can tolerate. So the 280-pounder, whose previous leisure activities had been purely nutritional, can expect to reduce his weight and change his shape by exercising to develop a runner’s physique. However, skin has limits both to elasticity and in its ability to retract once overstretched, so the excess will remain visible however assiduously that individual maintains the training program. The Future of Running A problem with genetic differences is that competition can never be between physical or physiological equals. This leads inexorably to the vexing question about what aids to improved performance may be considered both legal and sporting. This book deals solely with training methods. One factor in the improvement of running performance that is unquestionably lawful is simple leisure training. Until the last 30 or so years of the 20th century, almost all books written about running were biographies or ghosted autobiographies of the great retired runners who were hoping to make a few cents by passing on the secrets of their successes. Most of the books dealt with the races, although some had fascinating accounts of the runners’ preparations—and all too often the lack of it! Although the majority of those competitors were amateurs, at least in name, the elite runners of today are as much professionals as lawyers or doctors. Running for them is a full-time occupation for which they put in hours of preparation, travel around the world to compete, and are paid regularly by sponsors and promoters for their efforts. However, the average participant in the marathon explosion of the 1980s had little desire to run as far or as fast as the Kuts, Shorters, Zatopeks, and Coes of preceding generations. Running had become a socially acceptable leisure activity, which helped to counteract the similar growth in eating away from home. Running a few pleasurable miles with some friends and then replacing the calories in an equally enjoyable fashion became the new modus vivendi. Competition ceased to be the only goal of the runner, and running could be enjoyed for itself and the feel-good factor it produced. However, although the leisure runner became happy to commune with nature in his or her own particular fashion, it did not end all desire to improve performance, whether it be in speed or the distance covered. Running magazines began to appear on the shelves, which not only listed races and their results but also delved into nutrition, training, fluid intake and output, and all the little nuances that became part of a runner’s world. The effect of running on health, medicine, and even the psychology of the sport became regular dinner-table discussion topics. The desire to gain further health benefits and improvement from running can be advanced only if there is an understanding of the mechanism of running. Which muscles are needed in order to run, and how do they work? What part do the heart, lungs, and circulation play in this process? What are tendons, ligaments, and bursas, and why is running sometimes painful? This book sets out to answer all these questions. It also explains anatomy, the structural science dealing with all the phases of the running stride, how the muscles are employed, and the exercises that will improve strength, power, and endurance. The determined competitor also needs an appreciation of basic physiology, without which the muscles cannot function, so they may reap the full benefits of accepted science. Our hope is that by following this guide, some of today’s leisure runners may become the Olympians of tomorrow. CHAPTER 2 CARDIOVASCULAR AND CARDIORESPIRATORY COMPONENTS Improvement in running performance hinges on many factors. Specifically, running training benefits the cardiovascular and cardiorespiratory systems, which should, in turn, lead to an improvement in running performance. However, this improvement can be curtailed by neglecting or abusing the musculoskeletal system through inappropriate training—too much mileage at too fast a pace. Even intelligent training can exacerbate muscle imbalances and anatomical shortcomings. Incorporating strength training into a holistic plan for performance enhancement makes sense on many levels. A well- designed strength program promotes running efficiency through a better, more effective gait. A well-designed running program following some simple, proven tenets or best practices improves running economy by improving cardiovascular and cardiorespiratory efficiency. This chapter explains the general concept of running training via the cardiovascular and cardiorespiratory systems, and how positive anatomical changes can occur as a result of an educated, intelligent approach to training. Cardiovascular and Cardiorespiratory Systems The cardiovascular system is a circulatory blood delivery system involving the heart, blood, and blood vessels (veins and arteries). Put simply, the heart pumps blood. The blood is carried away from the heart by arteries and returned to the heart by veins (figure 2.1). Figure 2.1 Blood flows through the chambers of the heart. The cardiorespiratory system involves the heart and lungs. Air is inhaled by breathing through the mouth and nose. The diaphragm and other muscles push the air into the lungs, where the oxygen contained in the air becomes mixed with blood (figure 2.2). Figure 2.3 shows the muscles that work during respiration. The interplay between the two systems works when the heart pumps blood to the lungs through the pulmonary arteries. This blood is mixed with the air (oxygen) that has been inhaled. The oxygenated blood is delivered back to the heart via the pulmonary veins. The heart’s arteries then pump the blood, now complete with oxygen-rich red blood cells, to the body’s muscles (figure 2.4) to promote movement—in this example, running. Figure 2.2 Oxygen exchange in the lungs. Figure 2.3 Muscles that aid in respiration. How can running performance improve as a result of this interplay between the cardiovascular and cardiorespiratory systems? Simply, the more developed your cardiovascular and cardiorespiratory systems are, the more blood flow your body produces. Greater blood flow means more oxygen-rich red blood cells are available to power your muscles and more plasma is available to aid in creating energy through a process called glycolysis. Figure 2.4 Circulation of blood through the heart, lungs, and muscles. Other factors such as neuromuscular fitness, muscular endurance, strength, and flexibility are involved in improving running performance. Coupled with the strong foundation of well-developed cardiothoracic systems (the heart and lungs are located in the thorax region of the body, hence the term cardiothorax), these other factors will help to produce sustainable improvements in performance. The science described in the preceding paragraphs becomes exercise science, and a useful primer for improving running performance when applied to a training model. The following discussion of training is rooted in the anatomy and physiology of the cardiovascular and cardiorespiratory systems. Performance Training Progression Traditional training progressions consist of a well-developed base, or introductory, period consisting of easy runs of gradually increasing duration and strength training consisting of lighter weights and higher repetitions. Normally this period is followed by a slightly shorter but still significantly lengthy duration of running strength training (threshold training and hills) and strength training incorporating increasing resistance. The final phase is defined by a brief period of high-intensity ( V O2 max) running coupled with a maintenance period of resistance training and planned rest (taper). The entire training progression ends with a competitive phase of racing, which seems incredibly short given the amount of time spent attaining the fitness to race. This training progression, also known as a training cycle, is then adapted based on its success or failure and race distances to be completed in the future and repeated, incorporating a well-defined rest period at the end of each cycle, for the duration of the runner’s performance-based running career. Please note that this is by no means the only concept of how running training should be structured. Ideas such as adaptive training and functional training (Gambetta’s Athletic Development, Human Kinetics) are successful approaches to running training; however, the nuances of those training philosophies are not outlined in this book. Often, apparent differences in training philosophy boil down to simple semantics. Since training language is not codified, coaches do not always understand and apply terminology the same way. Our goal is to present an overall concept of the training progression in a simple but thorough manner without arguing the merits of different approaches. Base, or Introductory, Training The concept of base, or introductory, training is relatively simple, but the application is slightly more nuanced. Most coaches would agree that the pace of running during this phase is always easy and aerobic (based on the consumption of oxygen), not strenuous and anaerobic (using the oxygen present), and that the volume of training should gradually increase with down, or lesser-volume, weeks used to buffer the increase in volume, aid in recovery, and promote an adaption to a new training load. One systematic approach using a three-week training cycle incorporates four to six days of running training with a weekly increase in volume of 10 percent from week 1 to week 2; week 3 returns to the volume of the first week. For injury prevention, the weekly long run should not be more than 33 percent of the week’s total volume. Two or three strength-training sessions emphasizing proper form and movement, not volume of weight, would complement this running training. For a runner who is training for a race longer than a 10K, this phase of the training cycle is the lengthiest of a training progression because of the slower (relative to speed and muscle development) adaptations to training made by the cardiothoracic systems. Because relatively slow-paced aerobic runs take longer, they require the repeated inhalation of oxygen, the repetitive pumping of the heart, and the uninterrupted (ideally) flow of blood from the lungs to the heart and from the heart to the muscles. All of these actions aid in capillary development and improved blood flow. Increased capillary development aids both in delivering more blood to muscles and in the

removal of waste products from muscles and other tissue that could impede the proper functioning of the muscles. However, these adaptations take time. The development of a distance runner may take a decade or more, while the development of faster-paced running can occur in half the time. A training program that ignores or diminishes the importance of the base training component is a training program that ignores the tenets of exercise science. Without an extensive reliance on easy aerobic running, any performance-enhancement training program is destined for failure. A common question is how long the base period should last. This seemingly simple question does not have a simple answer, but the best reply is that the base period needs to last as long as the athlete needs to develop good running fitness and musculoskeletal strength based on his or her subjective interpretation of how easy the daily runs feel, but not so long that the athlete becomes bored or unmotivated. A good guideline for experienced runners who are training for races longer than 10K is six to eight weeks. Experienced runners training for 10K races or shorter distances need four to six weeks. For beginning runners, the base period takes longer, even making up the bulk of their first four to six months of running. Another common question is how fast the athlete should run. Short of getting a lactate threshold or stress test, which normally indicates approximately 70 to 75 percent of maximum heart rate or 70 percent of V O2max, pace charts help determine aerobic training paces based on race performances (Daniels’ Running Formula, Second Edition, Human Kinetics). They are extremely accurate and offer explanations of how to use the data effectively. An emphasis on base, or introductory, training does not mean that other types of training are ignored or diminished in importance. The other types of running training—tempo, lactate, threshold, steady-state, hill, and VO2 max—are relegated to their specific roles in a well-designed training program. Also, neuromuscular development is needed to allow fast performances to occur. These other types of training are meant to sharpen and focus the endurance developed during the base, or introductory, phase. However, because these other types of training also strengthen the cardiovascular and cardiorespiratory systems, they play an essential role in improving performance. The best approach to strength training during this phase is to perform multiple sets of 10 to 12 repetitions of exercises for total-body strength development. Specifically, at this stage of training, functional strength is less important than developing muscular endurance for the whole body. If this is an athlete’s first strength-training progression, the proper execution of the exercise becomes paramount. If an athlete is revisiting strength training after a rest period, becoming reacquainted with the physical demands of combining a running and strength-training program should be the goal. Strength training should be performed two or three times per week; however, one day a week should be entirely free of exercise, so the other workouts need to be performed either on running days after the runs or on the other off days from running if following a four- or five-day-a-week running plan. Threshold Training The concept of lactate threshold (LT) often associated with tempo-based running is a conversation point for many exercise physiologists, running coaches, and runners. The science of the concept, the lexicon to describe it, and the appropriate duration and pace of the effort offer endless possibilities for debate and argument. All too often an athlete’s successful performance leads to the supposition that his or her interpretation of threshold training (if it is a cornerstone of the program) is the appropriate interpretation and therefore must be copied by the masses. We do not endeavor to make any definitive statements about lactate threshold protocols. We apply the term threshold (please feel free to substitute lactate threshold, anaerobic threshold, lactate turn point, or lactate curve) to describe the type of running that, because of the muscle contractions inherent in faster-paced training, produces a rising blood-lactate concentration that inhibits faster running or lengthier running at the same speed (figure 2.5)—or, less scientifically, a comfortably hard effort that one could sustain for approximately 5 to 6 miles (8 to 10 km) before reaching exhaustion. It is very close to 10K race pace. Lactate—not lactic acid—is a fuel that is used by the muscles during prolonged exercise. Lactate released from the muscle is converted in the liver to glucose, which is then used as an energy source. It had been argued for years that lactic acid (chemically not the same compound as lactate, but normally used as a synonym) was the culprit when discussing performance-limiting chemical by-products caused by intense physical effort. Instead, rather than cause fatigue, lactate can actually help to delay a possible lowering of blood glucose concentration, and ultimately can aid performance. Threshold training also aids running performance because it provides a greater stimulus to the cardiothoracic systems than basic aerobic or recovery runs, and it does so without a correspondingly high impact on the musculoskeletal system because of its shorter duration. By running at a comfortably hard effort for 15 to 50 minutes (depending on your goal race and timing of the effort in your training program), you can accelerate the rate at which your cardiothoracic systems develop. Tempo runs, which are often referred to interchangeably with lactate threshold runs, cruise intervals, and steady-state runs, which are slightly slower than tempos, are types of threshold workouts, just at slightly different paces and durations. Ultimately, the objective of a lactate-type run, a measurement of 4 mmol of lactate if blood was drawn at points during the run, would be accomplished performing these runs instead of an easy aerobic run, which would produce almost no lactate. A good resource on tempo-type training is Jack Daniels’ Running Formula (Human Kinetics, 2005). The author recommends paces and durations of effort based on the athlete’s current fitness and race distances to be attempted. Although less stressful on the runner’s body than V O2 max efforts and races, threshold runs in any form (lactate threshold, tempo runs, cruise intervals, repeat miles) require longer periods of recovery than daily aerobic or recovery runs. Most nonelite runners should perform threshold-type runs no more than once a week during this phase of the training progression, and need to treat them as hard efforts. They should be preceded by an easy run plus a set of strides (faster running at 40 to 60 meters [44 to 66 yards]) the day before, and an easy or easy and long run the following day. Keep in mind that easy running still makes up the majority of this phase of training. The introduction of threshold-type training to the progression usually is the only difference from the introductory phase. Figure 2.5 Oxygen consumption relative to exercise intensity. Strength training at this phase of a training progression is highly important and highly individual. The emphasis should be on countering the athlete’s weakness and on functional exercises that directly correlate to running faster. For example, if a female runner lacks arm strength, an emphasis on arm exercises with lower reps (four to six) and higher weight (to exhaustion) would be called for. Also, if she was training for a 5K, functional hamstring strength would be important, so instead of performing hamstring curls, which emphasize only the hamstrings, the dumbbell Romanian deadlift and good morning exercises are more powerful exercises because they involve more of the anatomy (hamstring and glute complex) involved in the running gait. The hamstring curls should be performed in the base phase of training to develop general strength. Two strength-training workouts per week will suffice because of the intensity of the training. The muscle fibers must have a period of rest to repair themselves so they can adapt to an increasing workload. V 2 max Training Many exercise physiologists consider V O2 max and·V O2 max training to be the most important components of a comprehensive running program; however, this view has been challenged by some of the younger coaches who are not scientists but have had success in running and coaching. Regardless of bias, V O2 max-specific workouts are a powerful training tool for improving running performance—after performing the training leading up to it. V O2 max is the peak rate of oxygen consumed during maximal or exhaustive exercise (see figure 2.5). Various tests involving exercising to exhaustion can be done to determine a V O2 max score (both a raw number and an adjusted one). Once a V O2 max score is obtained, a runner can develop a training program that incorporates training at heart rate levels that equate to V O2 max levels. The training efforts, or repetitions, would not necessarily end in exhaustion, although they can, but would reach the heart rate equivalent of the V O2 max effort for a short period, approximately three to five minutes. The goal of this type of training is multifold. It requires the muscles incorporated to contract at such a fast pace as to be fully engaged, aiding in the neuromuscular component by placing a premium on nervous system coordination of the muscles involved in running at such a fast rate. Most important, it requires the cardiovascular and cardiorespiratory systems to work at peak efficiency to deliver oxygen-rich blood to the muscles and to remove the waste products of the glycolytic (energy-producing) process. Training at V O2 max levels is obviously a powerful training tool because of its intense recruitment of many of the body’s systems. It is important to note that a V O2 max training phase needs to be incorporated at the appropriate time in a training cycle for the runner to fully benefit from its application. Despite some athletes’ reporting success by reversing the training progression and performing V O2 max workouts at the beginning of a training cycle, the most opportune time to add V O2 max training to a performance-based training plan is after a lengthy base period of easy aerobic or recovery training and a period of threshold training geared to the specific event to be completed. Rest is an important component of this phase since it aids in adaptation to the intense stimulus of the V O2 max workouts. Do not be fooled into thinking that intense workouts and multiple races without rest is an intelligent training plan. It may deliver short-term success, but ultimately will lead to injury or excessive fatigue. The strength training performed at this stage should be a set of exercises that are highly functional and specific to the event being contested and the literal strength of the runner. For example, a marathon runner who has a strong core would focus on his or her core with multiple sets of 12 reps. The exercises are equally divided between abdominal exercises and lower back exercises to ensure balance. The emphasis is on muscular endurance. A 5K runner whose focus is speed would continue with the lower-rep, higher-weight routine of the threshold phase, emphasizing the upper legs, core, and upper torso. Results of the Training Progression Model As in math, each training phase builds on the by-products of the completion of the preceding phase. They are not isolated blocks, but an integrated system. For example, a completed base, or introductory, phase leads to increased capillary development, resulting in more blood volume, musculoskeletal enhancement, and, theoretically, a more efficient gait. Threshold training furthers the performance of the runner by advancing the development of the cardiothoracic systems, increasing the adaptation of the musculoskeletal system through faster muscle contractions, and heightening the body’s neurological response to stimulus (faster-paced running). Anaerobic training (using oxygen already present) has little practical application to distance running, and for most nonelite runners does not factor into the training progression. When these conditions have been met, the runner can easily begin a short course of high-intensity V O2 max training. The specifics of pace, duration, and rest are found in many training manuals, and the specific application of this type of training varies by individual. By following the strength- training recommendations for each phase of the running training progression, a runner is really preparing his or her body for the rigors of a goal race or races. The result of following a training program based on the development of

the cardiothoracic systems is better performance through an improved “engine” (the heart and lungs) and a stronger “chassis” through strength training. Whether V O2 max is determined by the exhaustion of the heart first or the muscles first, the development of the cardiothoracic systems will permit the point of exhaustion to be reached (measured in heart rate) at a faster pace and allow a greater distance to be covered. This is a visible way that improvement in performance can be measured. CHAPTER 3 THE RUNNER IN MOTION How do humans run? Is running just a faster version of walking? Is there a proper running form? Can I improve my running form? These are questions that many runners ask running experts, be they MDs, PhDs, running coaches, or fellow runners with more experience. The answers to these questions are complicated, but ultimately answerable, with a little knowledge of exercise science. This chapter explains the hows of running. Ultimately, an explanation of the gait cycle is worthy of doctoral study by researchers studying the biomechanics of running. The overview presented here provides runners with a basic understanding of the anatomy involved, the biomechanics that engage and disengage the anatomy, and the kinesthetic results that occur from initiating the running motion. The drills included in this chapter are designed to aid the runner in perfecting the running form by fine-tuning the gait cycle. Running Gait Cycle Running can be understood by using an analysis of the gait cycle. Unlike walking, which is defined by having both feet simultaneously in contact with the ground during a cycle, running is characterized by having both feet off the ground during a cycle (a cycle is defined as the period between when one foot makes initial contact with the ground until the same foot reconnects with the ground). The two phases of the gait cycle are the stance, or support, phase and the swing phase. When one leg is in the stance phase, the other is in the swing phase. The stance phase is marked by the foot’s initial contact with the ground (foot strike), midstance through toe-off and takeoff. This phase has been measured at approximately 40 percent of the gait cycle; however, for elite distance runners and sprinters it represents considerably less of the total phase. The swing phase begins with the float, which morphs into the forward swing or swing reversal, and finishes with the landing or absorption, which begins the next cycle. In the illustration (figure 3.1), the right leg is in the stance phase (making contact with the ground), and the left leg is in the swing phase, preparing to make contact with the ground. Figure 3.1 The gait cycle: (a) initial contact, (b) stance phase, (c) takeoff, and (d) forward swing phase. Stance Phase The quadriceps group, specifically the rectus femoris, is heavily active before initial contact. Once contact is made, the muscles, tendons, bones, and joints of the foot and lower leg function to dissipate the impact of the landing. Specifically, as described in chapter 9, three related but separate foot movements occur. The subtalar joint inverts and everts, the midfoot abducts or adducts, and the forefoot dorsiflexes and plantarflexes. Ideally, through this interaction of the anatomy of the lower leg, a small amount of pronation, the inward collapsing of the rear foot, occurs. This pronation helps dissipate the shock of the landing by spreading the impact over the full surface of the foot at midstance. An underpronated foot at midstance is less prepared to cushion the impact of landing because only the lateral aspect of the foot is in contact with the ground. This type of biomechanics can lead to chronically tight Achilles tendons, posterior calf strains, lateral knee pain, and iliotibial band tightness (all covered in chapter 10). Conversely, an overpronated foot at midstance can result in tibia pain, anterior calf injuries, and medial-side knee pain because of the internal rotation of the tibia. Neither extreme, a high rigid arch that underpronates or supinates or a low hypermobile arch, is ideal. Mild to moderate pronation is normal and very effective at combating impact stress. Swing Phase After the initial contact and midstance positioning, the hamstrings and hip flexors, the quadriceps, and the muscles of the calf (gastrocnemius and soleus) work in conjunction to allow a proper takeoff. While one leg is moving through its gait cycle, the other leg is preparing to begin a cycle of its own. Having already contacted the ground, this leg begins its forward motion as a result of the forward rotation of the pelvis and the concurrent hip flexion caused by the psoas muscles. As the leg passes through the forward swing phase, the hamstrings lengthen, limiting the forward extension of the lower leg, which had been extended by the quadriceps. The lower leg and foot begin to descend to the running surface as the torso accelerates, creating a vertical line from head to toe upon impact. Note that two cycles, one by each leg, are happening simultaneously. As one foot takes off the ground to begin its swing phase, the other leg is preparing to begin its stance phase. The dynamic nature of the running movement makes isolating the anatomy involved difficult because, unlike in walking, potential energy (the energy stored within a physical system) and kinetic energy (the energy of a body resulting from its motion) are simultaneous. Essentially, the anatomy involved in running is constantly turned on both as agonists, muscles that are prime movers, and antagonists, muscles with opposing or stabilizing motion. In walking, the muscles are either one or the other during the gait cycle. The role of the core during the stance phase is identical to its role in the swing phase, providing stability for the upper body, which allows the pelvis to twist and rotate in its normal manner. Because the gait cycle is defined by each leg moving through the stance or swing phase simultaneously, stabilizing the pelvis so it can function appropriately is an important task. A more lengthy discussion of the core is found in chapter 7, but suffice it to say that an unstable core could potentially lead to injury because of the gait cycle being negatively impacted. The arms also function to stabilize and balance, but in a slightly different way. Each arm counterbalances the opposite leg, so when the right leg swings forward, the left arms swings, and vice versa. Also, the arms counterbalance each other, keeping the torso stable and in good position and ensuring that arm carriage is forward and back, not side to side in a swaying motion. Poor arm carriage ultimately costs the runner both by hindering running efficiency (stride length is shortened as a result of the legs “following” the swaying arms and rocking slightly) and running economy (poor form requires a dramatic increase in energy consumption). Given the explanation that the gait cycle can be understood as each leg performing a cycle simultaneously, and that the same anatomy (i.e., muscles, tendons, and joints) are performing multiple functions simultaneously, it is reasonable to assume that a breakdown, or failure, in the kinetic chain is likely. This breakdown usually occurs because of inherent biomechanical imbalances that are exacerbated by the dynamic repetition of the running motion. For example, the quadriceps group and the hamstrings group are both involved in the landing phase of the gait cycle. The quadriceps group serves to extend the leg and the hamstrings limit flexion at the knee. Because the quadriceps group is dramatically stronger, the hamstrings must be able to work at their optimal capacity for the movement to be fluid. If the hamstrings group is weakened or inflexible, an imbalance exists that will ultimately lead to an injury. This is just an obvious example of the injury potential of anatomical imbalances. To counteract this scenario and others, this book offers a comprehensive strength-training regimen. The exercises are geared to complement each other by developing both the agonist and antagonist muscles as well as strengthening joints. ABC Running Drills Other than with strength training, how can running form and performance be improved? Because running has a neuromuscular component, running form can be improved through form drills that coordinate the movements of the involved anatomy. The drills, developed by coach Gerard Mach in the 1950s, are simple to perform and cause little impact stress to the body. Essentially, the drills, commonly referred to as the ABCs of running, isolate the phases of the gait cycle: knee lift, upper leg motion, and pushoff. By isolating each phase and slowing the movement, the drills, when properly performed, aid the runner’s kinesthetic sense, promote neuromuscular response, and emphasize strength development. A properly performed drill should lead to proper running form because the former becomes the latter, just at a faster velocity. Originally these drills were designed for sprinters, but they can be used by all runners. Drills should be performed once or twice a week and can be completed in 15 minutes. Focus on proper form. A Motion The A motion (figure 3.2; the movement can be performed while walking or more dynamically as the A skip or A run) is propelled by the hip flexors and quadriceps. Knee flexion occurs, and the pelvis is rotated forward. The arm carriage is simple and used to balance the action of the lower body as opposed to propelling it. The arm opposite to the raised leg is bent 90 degrees at the elbow, and it swings forward and back like a pendulum, the shoulder joint acting as a fulcrum. The opposite arm is also moving simultaneously in the opposite direction. Both hands should be held loosely at the wrist joints and should not be raised above shoulder level. The emphasis is on driving down the swing leg, which initiates the knee lift of the other leg. Figure 3.2 (a) A motion 1, (b) A motion 2, and (c) A motion 3. B Motion The B motion (figure 3.3) is dependent on the quadriceps to extend the leg and the hamstrings to drive the leg groundward, preparing for the impact phase. In order, the quadriceps extend the leg from the position of the A motion to potential full extension, and then the hamstrings group acts to forcefully drive the lower leg and foot to the ground. During running the tibialis anterior dorsiflexes the ankle, which positions the foot for the appropriate heel landing; however, while performing the B motion, dorsiflexion should be minimized so that the foot lands closer to midstance. This allows for less impact solely on the heel, and because the biomechanics of the foot are not involved as in running, it does not promote any forefoot injuries. Figure 3.3 (a) B motion 1, (b) B motion 2, and (c) B motion 3. C Motion The final phase of the running gait cycle is dominated by the hamstrings. Upon impact, the hamstrings continue to contract, not to limit the extension of the leg but to pull the foot upward, under the glutes, to begin another cycle. The emphasis of this exercise (figure 3.4) is to pull the foot up, directly under the buttocks, shortening the arc and the length of time performing the phase so that another stride can be commenced. This exercise is performed rapidly, in staccato-like bursts. The arms are swinging quickly, mimicking the faster movement of the legs, and the hands come a little higher and closer to the body than in either the A or B motions. A more pronounced forward lean of the torso, similar to the body position while sprinting, helps to facilitate this motion. Figure 3.4 (a) C motion 1, and (b) C motion 2. CHAPTER 4 ADAPTATIONS FOR FOR SPEED AND TERRAIN Every runner has a vision of the perfect run—beautiful views; a gentle, cooling breeze; a benign, perhaps slightly downhill surface; and a loving companion. Sadly, the real world is rarely like that, and we all have to make do with some sort of compromise on these fronts. The weather may be wet, windy, and cold; the surface rutted and uneven; the view industrial; and the companion a rival. In such circumstances one’s body and mind have to adapt to the prevailing conditions—either that or give up completely! This chapter deals with the adaptations that

can be made to cope with everything our sport throws at us. Although we have used athletes from the extreme ends of the running spectrum to illustrate the points, most runners will find a compromise somewhere between the various limits that are discussed. Event-Specific Body Characteristics When you attend a track and field meet, it is not too difficult to make an educated guess about the events in which most competitors will compete. The sprinters and high hurdlers are often so physically developed that they appear muscle-bound. Generally, the bodies of the 400-meter to 1,500-meter athletes become progressively less well built and smaller in stature the further the distance raced. Finally, the long-distance runners may seem unnaturally thin or even undernourished, even if their performance in a race soon belies this. That you are able to tell roughly what type of body image fits which runner indicates that the diversity of training for an event has created structural differences in the runner. It is perhaps easiest to consider the two extremes—that of the 100-meter sprinter and the marathon runner. Not only is the latter perhaps some 10 years older, but also the years of training will have shaved most of the surplus fat from his or her torso. The sprinter may also carry minimal fat, but appears to be a much more physical presence, for not only is he or she likely to be taller, but the rib cage of the short-distance runner is covered by layers of structural muscle as well, augmented by the training program, which the marathoning counterpart lacks. In the upper body, the arms are part of the sprinting mechanism. No one could envisage sprinting without a lot of arm action, yet for the distance runner the arms are little more than a means of balancing, to such an extent that it is not unusual to see runners who are trying to relax running with their arms dangling by their sides and only starting to use them in a finishing sprint. That said, it is quite common for runners to complain of arm pain at the end of a long race, especially if they have given no thought at all to preparation for several hours of repetitively swinging each shoulder through the few degrees of movement that has been required for the effort. That the arms are needed for balance is demonstrated clearly by the hill runner, who will invariably speed downhill with arms held quite widely open, even though this is partly to prevent injury in case of a fall. Further differences occur in the stride length (figure 4.1). Sprinting is all about high speed. The legs can only be moved so many times a second, but anyone who can cover more ground with each stride will move further ahead of the field in an equal number of strides. The difficulty is in the repetition of the long strides, for the energy expended is far greater than that involved in taking shorter paces, which explains why sprinters do not win long-distance races. To gain the extra reach, the thighs need to be stronger, so they become bulkier and heavier, which limits their flexibility and can eventually become self-defeating if taken to extremes. Accessory muscles in the lower abdomen and pelvis also develop to help lift the thighs higher. For the same reason, the knees flex more at sprinting speed and the calves may touch the hamstring muscles when sprinters are in full flight. Figure 4.1 Physical adaptations to different running speeds: (a) shuffle; (b) finishing kick or sprint. Effects of Terrain and Other External Factors The sprinter has little to worry about underfoot. For the past 40 years the majority of tracks have been built with a rubbery surface, which aids elastic rebound after landing. These were a source of considerable injury when first introduced because of the shock of the bounce-back and the Doppler effect on the untrained muscles and Achilles tendons. Training on these tracks as they have become more numerous has helped to reduce incidence of injury. This is not the case for longer-distance runners after they leave the track. Roads themselves vary from hard concrete to soft tarmac; even standing water changes the forces produced on landing. All of these alter the shock waves and response within the lower limbs particularly. Even more difficult is the adaptation by the hill or mountain runner, who not only has to ascend and descend vertically (figure 4.2), but may also have to run slopes diagonally. This produces excessive forces not only on the lower limbs (figure 4.3), as the ankle joints need to prepare for constant inversion and eversion, but also on the knees and hips and the pelvis. The consequence of this may be a scoliotic, or twisted, lower back, which will soon become painful unless steps are taken to prepare for this type of running. Hills are the ultimate test of the ability to stay upright while running. If the runner is unstable, he or she will soon topple over. Those blessed with a low center of gravity have a head start, although their inherently short legs may not deliver a long stride. A thin torso is a factor under the control of the runner because it may lower the center of gravity; reducing weight overall also makes it easier to lift the body vertically. Flexibility of the spine, particularly the lumbar area, is also a virtue because the climber needs to incline into the slope and the descender needs to lean backward to avoid the center of gravity from being moved forward horizontally by the running action. It follows that the hips have to be more flexible to compensate for the decreased range of motion in the spine that the need to lean causes. Although the muscles that are used to run hills are the same, the emphasis changes. The erector spinae and iliopsoas have more work to do while climbing because a tilted spine requires more effort to hold it stable than a vertical one, where the vertebrae generally just sit on top of each other. Descent places greater stresses on the anterior muscles of the calves and thighs, which have to absorb the impact of landing as well as the effect of gravity. Because running on flat surfaces cannot adequately prepare any runner for hills, some of the training should involve climbing, even if stairs alone are used. Downhill training is more difficult if the runner lives on flat terrain, although as a last resort, stepping, both up and down, can give some experience of the problems and training for hills, especially if maintained for several minutes. Climbing muscles in the calves and anterior thighs can be strengthened using the exercises in chapter 9. Figure 4.2 Running (a) up an incline or (b) down a decline requires physical adaptations. Figure 4.3 The lower legs and feet must adapt to (a) inclines and (b) declines. Cross-country running is sufficiently global to boast its own world championships, though all too often they are run on grassy parkland surfaces. The real aficionados prefer six miles or more of deep, gluelike mud from which they have to lift their legs out with each stride while attempting not to slip backward on the treacherous ground. Although the choice of footwear may aid movement, it does little to prepare for the increasingly exhausting effort that each stride demands compared to the rebound found on the roads. Bends and corners present their own difficulties. Runners have to lean into the corner at a right angle (figure 4.4), or they will fall flat on their sides. Indoor tracks are half the length of those outdoors and are steeply banked to allow runners to lean less obviously and be able to concentrate on staying in their own lanes as they double back through 180 degrees. Bend running stresses the lateral outer side of the lower limbs; the fasciae latae, the peroneal muscles, and the lateral ligaments of both outer knee and ankle have to take the extra force induced when turning. The medial side of the inner leg is similarly affected. Running indoors on the boards for the first time has been an awakening for many experienced runners who thought they knew it all! The shoes also have to absorb the lateral forces, so laterally rippled shoes that grip mud when running forward will give no help when the foot slides outward when a sharp corner is turned. Figure 4.4 Runners have to lean into corners on banked indoor tracks. Many roads have a camber, so if a runner persists in running along one particular side of the road, he effectively gives himself a leg-length difference; that is, one leg (that nearer the middle of the road) will appear shorter than the other, and the pelvis will inevitably be tilted. In order to compensate for this, the pelvis has to incline so the lumbar spine corrects itself by twisting to become vertical. If a runner needed a recipe for low back pain, this is it! As we cannot recommend running down the middle of the road either, local knowledge of heavily cambered roads or alternating sides may help to reduce the problem. For all these varied events, some training in near-competitive situations is invaluable. Although he wasn’t preparing for a running event, British racewalker Don Thompson prepared for the sapping humidity and heat of Rome in July for the 1960 Olympic 50K race by steaming himself in a heavy tracksuit with kettles of boiling water in the modest bathroom of his home. The result: an unexpected gold medal. This is an extreme example that we would strongly discourage following, but in general, practicing in conditions that resemble competition is unlikely to do any serious harm, especially if adequate time is left for recovery and lessons from the experience are learned. It may not be entirely possible for runners to simulate race conditions. The domination of long-distance races by Africans in the 21st century may be partly a result of evolution, but that itself is influenced by living at altitude and by a lifestyle that demands that they may need to run 5 or 10 miles each way to school in order to be educated. If the kids in Western civilizations had to do the same, might not they have similar successes? All training has to rely on the facilities available. A town-dwelling mountain runner is unlikely to have suitable slopes to train on at his doorstep. He or she can prepare to run at certain speeds, and may even use the stairs in a high-rise block to simulate some of the climbing action. It is more difficult to practice for a rugged, slippery, or stony surface, where a major objective is to avoid injury. It is at this point that thought about both preparation and the desired outcome is needed. If a run is likely to involve a diagonal downhill section, then the best results will come if the runner has added flexibility and strength to withstand the forces generated by the impact of landing many times on a foot that will be inverted and twisted inwardly. This stretches the ligaments on the outside of the ankle and the knee, and yet more shock is absorbed by the muscles on the outer side of the limb. Conversely, the other limb, higher up the slope, has the inner side stressed. If the runner realizes that this is going to occur, exercises to stretch and strengthen the appropriate soft tissues can and should be introduced into the training program. The way in which the body adapts to speed and terrain can be influenced by the training program used. Many years ago some runners trained using LSD—long slow distance. Unfortunately, this only made them good at running long distances slowly and led them to other problems in the form of overuse injury. It is not only human bodies that react badly to wearisome repetition; machines are not much different and also break down with long-term continuous use. One method of prevention is to vary the programs used. As sprinters have shown, fast running is about training the whole body. Some of this means running fast, but a large proportion of the program requires neither racing shoes nor a track.

It should be no different for distance runners, who should exercise specific parts as well as their whole bodies. Hills and rough and uneven surfaces can all be faced with more confidence if the body is prepared, especially if certain weaknesses are known. A cross-country runner who is aware that he or she loses ground in thick mud can perform exercises and training drills to strengthen the thigh muscles needed to haul him or her through. In each chapter of this book we have produced disciplines to cover all these eventualities, help you to adapt to the sort of running that you want or even may have to do, and aim to make you a better runner. If you are unable to adjust to the speed and terrain that you encounter during your runs, not only will the performance factor be lowered, but there is every chance that the enjoyment will disappear with it as well. External factors must be another consideration. No one in their right mind would wear a pair of spiked shoes for a road race, but the choice of clothing and shoes for the race may well help to determine the outcome. On a warm day, well-ventilated, airy, and pale-colored attire helps to reduce heat buildup from various external and internal sources. In contrast, warm protective clothes may help reduce the greater risk of injury that colder temperatures may induce. Although very light shoes are suitable for a short-distance race, a heavier pair may give more cushioning and protection to the lower limbs and back over a longer distance despite the weight increase. The composition of the shoe is an important factor in maximizing the value of a run. The upper parts of shoes fail to be waterproof after a heavy rainfall, though some materials will limit the ingress of water sufficiently to prevent the otherwise strong possibility of blistering and other skin conditions. The weight of the shoe should probably be in inverse proportion to the distance to be run. The grip on the ground underfoot is paramount. Spikes gain the best purchase but will ruin feet if used on tarmac or concrete, where rubber-based compounds have the most elasticity and facilitate a good rebound effect. On softer but still firm terrain, such as grass, spikes are ideal, but some runners prefer the sole to have a waffle or even a ridged effect where the ground is likely to be muddy (figure 4.5). Snow and ice present their own difficulties with the maintenance of grip. Spikes are often best, but then the runner has to beware of frostbite. Where hills and their often rocky surfaces are involved, there is debate as to which are the best shoes to provide grip for both uphill and downhill running, yet have sufficient cushioning to stop the landing at up to 10 times body weight from damaging heels and metatarsals. Experience will eventually allow the runner to decide on the most suitable shoe for any particular surface, and we discuss shoes more fully in chapter 11. Figure 4.5 Proper shoes help a runner keep his footing on muddy or gravelly surfaces. It is no coincidence that the fastest sprinters in the world make the majority of their appearances and all of their fastest runs in the summer months. Once the temperature drops below the mid-60s (F; high teens C), flexibility is lost in the ligaments and joints of the lower limbs and the blood flow through muscles will decrease as a result of the cooling. This is a certain recipe for injury, especially because winter preparation probably contained a large percentage of indoor training in warm clothing to simulate summer temperatures during which muscle volume and strength were built up. Sprinters require this body muscle bulk for the explosion of power needed in their events. This can only be obtained by repetitive training in muscle-friendly ambient temperatures with increasingly heavy weights and drills, which eventually produce the muscle definition so admired and effective in their events. Watching a slow-motion image of sprinters shows how they run with every muscle available. Look not only at their legs, but also watch the shoulders, arms, neck, and even the lips of a sprinter running flat out to visualize how the winner is the one who has trained each of these elements individually and hardest. Usain Bolt did not just happen! Even if you do not have a coach with whom to discuss your objectives, there is nothing to stop you from jotting these ideas down to discuss with fellow runners. If you plan a race while on vacation, forethought about the conditions—both the weather and the terrain—could pay dividends. It could be a flat race but with one big climb up or down, or both. This will require an adaptation of your speed for that segment of the run, so acceleration during the training sessions at the appropriate point and a simulation of the hill will help your body to strengthen itself for the contest ahead. We have given you exercises to help prepare yourself for such conditions—we cannot anticipate the conditions themselves, which remain your responsibility. If you follow the ideas, your body should adapt optimally to your running needs and enable you to achieve your full potential. CHAPTER 5 UPPER TORSO Anyone who understands the function of a bellows or an accordion will soon grasp the anatomy of the thorax, commonly known as the chest. Bellows and accordions have evolved over many years as a way to move air under pressure and produce an air current or musical sounds. The principal bony architecture of the chest (figure 5.1) consists of 12 thoracic vertebrae, each placed one on top of another, but interlocked by ligaments and other soft tissues in such a manner that there can be movement in anterior (front) and posterior (rear) directions, limited lateral (side) motion, and a degree of rotation that allows the torso to twist. Emerging from the side of every thoracic vertebra are two bony ribs that encircle the body and meet at the front, the majority of them forming the sternum, or breastbone. Figure 5.1 Bony structures of the torso: ribs, sternum, and vertebrae. Although the outside or posterior of the vertebrae are supported by the erector spinae muscles, which run the length of the spine, each rib hangs from the one above, held together by the intercostal muscles, much in the fashion of a venetian blind. Without further structural support, these would be unstable, so the trapezius, latissimus dorsi, rhomboid, teres group, shoulder stabilizers, and pectoralis major and minor (figure 5.2) all aid in the maintenance of the relative position of the ribs. At the base of this dome, with attachments to the lower ribs, lies the vast diaphragm, encircling the base of the thorax. Further stability is given by the abdominal muscles, rectus abdominis, the external oblique, and serratus anterior. Running makes far greater demands on the body for oxygen than does sedentary life. The diaphragm uses a bellowslike action as it contracts to draw air into the lungs. At the same time, the intercostal muscles relax, only to contract strongly as expiration occurs, during which time the diaphragm relaxes and is drawn up into the thorax. Using this push-pull endeavor, the lungs fill with air and empty to maintain the oxygen needs of the runner. Figure 5.2 Upper torso: (a) front view and (b) back view. As well as their action in the mechanisms of breathing, the muscles of the thorax have a limited but significant part to play in forward motion. The best way to appreciate this is to view an approaching runner in slow motion. As the thigh moves forward with each stride, the pelvis rotates slightly, first one side, and then the other. This twists the spine a little and would cause instability within the abdomen and thorax if unchecked, so a small but significant tensing and relaxation of the thoracic musculature helps not only to maintain the vertical component, but also to correct variations that are caused by forward motion of anything up to 20 miles per hour (32 k/hr). The muscles that are attached to the shoulders and humerus, particularly the pectorals and teres, are also moved passively when the arms swing fore and aft with each stride. If they contract actively, they too will help move the upper arms to a small extent as they oppose the pull of the deltoid (figure 5.3). The importance of these muscles in running lies with the “weakest link” presumption—that the power of the runner is dependent not on the strength that he can produce but on which facet of his running body tires first. If the muscles of the thorax are undertrained and fatigued, they will be unable to perform their functions and so reduce the efficiency of the running action and the runner himself. If the thoracic muscles lose strength and power, not only is the breathing action compromised, but also the auxiliary actions to support the spine and aid the arm movement will be weakened, leading to an inevitable slowing. Having watched runners for many years, it is surprising how many feel that they can only improve if they increase the pace or quantity of their training. Many do not realize that the limits to their running will always be related to the weakest part of their body. The legs may be capable of a mile in under four minutes, but if the lungs do not have the capacity to provide oxygen to those legs, then they are only going to be able to achieve the speed allowed by the lungs, and not that of which the legs may be capable of under other circumstances. To avoid this disparity, the diaphragm and all the supporting muscles need to be just as fit as those of the lower limbs. These muscles become fatigued by exercise in exactly the same way as do all other muscles, so it seems logical that they need to be as highly trained as any other group of muscles involved in exercise. It is for that reason that the training exercises included here should be considered as important as all those that are prescribed for the legs. Figure 5.3 The deltoid. Choosing Resistance Initially, choose weights for each exercise that provide a moderate amount of resistance but that allow for the strength-training movement to be performed by maintaining proper technique for the entire set of repetitions. The weight should be increased as strength improves and adaption becomes apparent through easier performance of the exercise; however, the weight should never be so heavy that proper technique is compromised, even on the final few repetitions of a set. Factors such as which part of the anatomy is being strengthened also factor into the decision on weight used. For example, the pectoral muscle is large, and therefore can handle a large amount of work. The triceps, comprised of three much smaller muscles, fatigues quite quickly when it is the primary muscle group used; however, because the triceps is involved secondarily in many upper-body exercises, it will already be slightly fatigued before any triceps-specific exercises are performed. One triceps-specific exercise per strength-training session that involves the arms should suffice to strengthen the triceps sufficiently. Conversely, multiple chest exercises or many sets of the same exercise will be needed to sufficiently fatigue the larger pectoral muscle. Repetitions The amount of repetitions should vary based on the strength-training goal of the exercise and the objectives of the entire strength-training workout for that day. For example, two sets of 20 dumbbell presses and a set of 30 push-ups may function as an entire chest workout on a Monday, but on Friday, one set of 12 repetitions with a heavier weight than lifted Monday, followed by two sets of 10 repetitions of incline barbell presses and three sets of 15 push-ups may be what is called for. A general rule to follow is that the heavier the weight, the fewer reps performed, and vice versa. Breathing Exhale when forcibly moving the weight and inhale when performing the negative movement or resisting the weight. When generating movement, exhale; when resisting movement, inhale. The speed of each exercise should be as fluid and controlled as possible and should be in relationship

to the breathing pattern. An accepted breathing pattern is four seconds for the resistance (inhalation phase) and two seconds for the movement (exhalation phase). Schedule A varied resistance-training routine works best. The concept of work plus rest equals adaption has a caveat. The work must change over time both in quantity of work (amount of resistance) and in quality of work (type of exercise) to ensure continued strength gains. For each segment of the body examined in this book, we have provided multiple exercises, some with variations, that can be used to create a multitude of different strength-training sessions all geared toward strengthening the anatomy that is most involved in running. By changing exercises, the number of sets and repetitions, and the exercise order, runners can tailor their strength-training sessions to meet their fitness needs and time constraints. No workout need be longer than 30 minutes, and two to three sessions per week can dramatically enhance a runner’s performance by strengthening the specific anatomy used during run training and racing. We are not suggesting that just lifting weights will make you a better runner. We are suggesting that through proper strength training, your anatomy will be strengthened, and this resultant strength will aid running performance by eliminating muscle imbalances that impede the gait cycle, help in respiration, and help eliminate injuries that result from muscle imbalances. Dumbbell Press Execution 1. Lie supine (back down) on a bench with legs steepled and feet on the bench. There should be a small, natural bend in the lower back so it does not touch the bench. A dumbbell should be held in each hand, at chest level. 2. Press the dumbbells upward to full extension. When full extension is reached, immediately lower the dumbbells slowly to the original position. 3. Repeat the movement, keeping in mind the stable position of the back against the bench. Muscles Involved Primary: pectoralis major, triceps, anterior deltoid Secondary: biceps, rectus abdominis SAFETY TIP For the physioball dumbbell press variation, the weight of the dumbbells should be reduced because of the relative instability of the physioball versus the bench, but after becoming comfortable with the movements, dumbbell weight can be added. Running Focus As mentioned earlier in the chapter, the muscles of the chest become fatigued by exercise in exactly the same way as do all other muscles, so developing these muscles through a simple exercise like the dumbbell press is both easy and beneficial. This exercise recruits the abdominal group more than the barbell bench press because the torso requires stabilization as a result of the independence of each dumbbell. It targets the pectoral muscle group and uses the abdominal group as stabilizers. The stronger the abdominal and pectoral group are, the better the posture of a distance runner in the latter stages of a race or training run, as well as the cardiovascular benefit of improved respiration. The better the upper-body posture of a runner, the more efficient the gait cycle is, aiding the runner by not wasting precious energy on poor running mechanics. VARIATIONS Rotadet Dumbbell Press Dumbbell Press on Physioball This variation develops the sternal head of the pectoral groupIt helps fully develop the pectoral group. The use of the physioball enhances the role of the abdominal group as stabilizers for the exercise. Incline Barbell Press Execution 1. Lie on a 45-degree incline bench. With arms extended almost to their full extension, grip the barbell a little wider than shoulder width. 2. Fully extend the arms, removing the barbell from the rack. Lower the barbell in a straight line to the upper chest. 3. Press the barbell up, in a straight line, back to the original position without locking the elbows. Muscles Involved Primary: pectoralis major, triceps, anterior deltoid, serratus anterior Secondary: biceps, rectus abdominis SAFETY TIP Use of a spotter is highly recommended to help with removing and placing the barbell back on the stays of the bench. Because of the inclined nature of this exercise, there is more shoulder involvement—specifically, the rotator cuff. If any pain is felt in the shoulder, discontinue the exercise and perform only the flat dumbbell press. Running Focus Similar to the dumbbell press in the muscles engaged, the incline press also involves the serratus anterior, adding to the development of the upper body. By adding variation to a strength-training routine through the use of different exercises that stimulate muscle growth in the same area, a runner can avoid becoming bored with a regimen. Because the strength-training component is meant to complement and enhance run training, performing new exercises helps keep the training fresh. Dumbbell Fly Execution 1. Begin by lying supine on a bench with legs steepled and feet on the bench. There should be a small, natural bend in the lower back so it does not touch the bench. Arms are extended perpendicular to the body with 5 to 10 degrees flex in the elbows. Hands grip the dumbbells, palms facing inward. 2. Lower the weight slowly, focusing on the stretch of the pectoral muscles while maintaining bent elbows, until the upper arms are outstretched and in the same plane as the bench top. 3. Return the weight to the starting position as if you were hugging a barrel. Control the dumbbells so they do not touch at the top, but are separated by 2 or 3 inches. Muscles Involved Primary: pectoralis major Secondary: biceps, deltoid, extensor digitorum SAFETY TIP Note that you begin the exercise with the dumbbells extended, not outstretched. Lifting the dumbbells to begin the exercise can be difficult if heavy weight is used, and starting in the outstretched position places the deltoids and biceps in an awkward position. Also, do not lower the arms past the plane of the bench top for fear of injury. TECHNIQUE TIP ▶ When returning the weight to the overhead position, do not push the weight with your hands or overly engage your deltoids. Your pectorals should do the lifting. Running Focus The emphasis on strengthening the pectoral muscles has been noted in all the exercises listed in this chapter. However, the benefits of the dumbbell fly include the stretching of the pectoral muscles, specifically during the negative, or lowering, phase of the exercise. This stretching helps expand intercostal muscles between the ribs, allowing for better respiration. Essentially, the more the muscles of the chest are expanded, the easier it is to inhale oxygen. This is reflected in the large rib cages of elite marathoners like Ethiopian Haile Gebrselassie and American Ryan Hall. Their chests always seem expanded when they run, most likely to accommodate their exercise-enlarged lungs. Push-Up Execution 1. Start in a prone position, arms bent, slightly wider than shoulder-width apart, but in a straight line with the outsides of the shoulders. 2. Push away from the floor in a single, controlled movement, keeping your body in one slight upward plane (from feet to head) until your arms are fully extended. Exhale while performing the push-up. 3. Lower your body slowly by bending at the elbows until the chest is parallel and touching or near touching the floor. Inhale during this phase of the exercise. Muscles Involved Primary: pectoralis major, triceps, anterior deltoid Secondary: biceps, latissimus dorsi, rectus abdominis Running Focus The push-up is the purest strength exercise. No machines. No weights (other than your own body weight). One fluid movement. It is not complicated unless you add variations (incline push-up and push-up on physioball), but it is a highly effective exercise for developing upper-body strength. Push-ups benefit a runner by strengthening the upper body and abdominals, ensuring proper posture. The technique involved in completing a push-up is similar to the position of the upper body during running, so the exercise reinforces correct posture. Multiple sets of push-ups can be done, but like any strength-training activity, push-ups should not be done daily, but following a rest period that allows for the mending of the muscle fibers used during the push-up session. VARIATIONS Incline Push-Up Incline push-ups shift the emphasis of the exercise to the upper chest and the muscles of the shoulders. A greater number of push-ups can be performed, so incline push-ups are a good exercise to begin with if regular push-ups are difficult. Because the exercise is easier, you may be tempted to accelerate the motion, but resist this temptation. The rotator cuff is more involved in incline push-ups, and accelerating the motion could lead to a shoulder injury. Push-Up on Physioball Decline push-ups shift some of the emphasis to the upper back. Using a physioball while performing this exercise requires core stabilization, so this exercise aggressively targets secondary muscle groups. Try to keep your hips from sinking toward the ground during the execution of the push-up. Maintain a rigid posture. If this is difficult, use a smaller physioball, which makes the exercise easier. UPPERBACK Pull-Up Execution 1. Use an overhand (palms forward) grip and hang from the pull-up bar, getting a full stretch. 2. Pull your body weight upward using a fluid motion. 3. When the chin reaches bar height, lower your body in a controlled movement back to almost full extension of the arms. Feet should not touch the floor during repetitions. Muscles Involved Primary: latissimus dorsi, teres major, rhomboid Secondary: biceps, pectoralis major Running Focus The pull-up is the yin to the push-up’s yang. It is simply performed, but powerful in providing strength benefits. It helps strengthen the upper back, and as distance runners can attest, a strong upper back makes for better running posture during the later stages of a training run or long race. The U.S. Marine Corps and other branches of the military use the pull-up (and push-up) to measure the fitness of their soldiers. A perfect score is 20 pull-ups in one minute. Pull-ups are a difficult exercise. To aid in starting the exercise, stand on a box to begin the first rep. Do only the amount of pull-ups that can be done with a fluid, controlled movement. Do not wriggle or bounce. Often pull-ups are called chin-ups. Some trainers distinguish between pull-ups and chin-ups based on the grip (palms outward or inward), but for others the difference is simply semantic. VARIATION Reverse-Grip Pull-Up Use an underhand (palms facing toward you), shoulder-width grip. Hang from the pull-up bar, getting a full stretch. Pull your body weight upward using a fluid motion. When the chin reaches bar height, lower your body in a controlled movement back to almost full extension of the arms. Feet should not touch the floor during repetitions. The reverse-grip pull-up involves the biceps more than the overhand-grip pull-up. Given the relatively small size of the biceps, performing this exercise is more difficult than with the overhand grip because the biceps can fatigue quickly. The two pull-up exercises can be alternated during a strenuous upper back workout, or they can be done on different days as part of a general workout. UPPER BACK Machine Lat Pull-Down Execution 1. Using a weight machine, face the bar with your legs under the pads and grip the bar using a wide grip. Arms are fully extended. Palms face away from the body. Your upper body is slightly rotated (shoulders back) to accommodate the exercise motion. 2. In one continuous motion, pull the bar down, with elbows back and chest out until the bar reaches the upper chest. 3. Gradually allow the arms to return to full extension while resisting the weight during the negative phase of the exercise. Muscles Involved Primary: latissimus dorsi, teres major Secondary: triceps, deltoid TECHNIQUE TIP ▶ The lat pull-down will cause significant muscle mass to develop in the upper back if heavy weight is used as resistance. It is recommended to perform the exercise with lighter weight than the maximum and to complete multiple sets of higher repetitions. Running Focus The lat pull-down motion is not a normal running movement, so how does this exercise aid running performance? Like the chest and upper back exercises previously illustrated, the lat pull-down helps performance by strengthening muscles (latissimus dorsi and teres major) that support and stabilize the body’s thorax and aid in respiration and posture. The strengthening of the upper back helps counterbalance strength gained from performing the exercises targeting the chest, creating a torso that is balanced, and helps with maintaining

an erect posture throughout a lengthy training or racing session. This is a good exercise to perform during the introductory phase of training. VARIATION Reverse-Grip Lat Pull-Down This exercise emphasizes the role of the biceps as well as the latissimus dorsi and teres major. We recommend completing this exercise on a day when strengthening the arms is the focus of the workout. If you perform the lat pull-down first, you may need to change the weight load to perform the reverse-grip variation since the latter minimizes the role of the larger shoulder and upper back muscles. UPPER BACK One-Arm Dumbbell Row Execution 1. Kneel with one leg on a flat bench. Use the same-side hand (non-weight-holding hand) for support by placing it on the bench. The weight-holding hand is dropped below the bench top, arm extended down. 2. Grip the weight and, in a smooth, continuous motion initiated by the muscles of the upper back and shoulder, pull the dumbbell upward until the elbow is bent at a 90-degree angle. Exhale while performing the row. 3. Gradually lower the weight along the same path that the dumbbell traveled upward. Muscles Involved Primary: latissimus dorsi, teres major, posterior deltoid, biceps, trapezius Secondary: erector spinae, rectus abdominis, external oblique, internal oblique TECHNIQUE TIP ▶ The movement of the exercise has been likened to that of sawing wood with a hand saw. Running Focus This is an easy exercise to perform, and it benefits multiple muscles. Specifically, because a relatively heavy weight can be used (once good form is established), a lot of strength gains can occur. The development of the deltoid and trapezius will help with head position and arm carriage. Specifically, strength in these muscle groups will aid in developing a powerful arm carriage during track sessions, help fend off fatigue during longer workouts and races, and help maintain good running form during trail runs on difficult (rocky or hilly) terrain. An important element of this exercise is the isolation of the upper back and shoulder muscles used. Although the abdominal group engages to stabilize the body, emphasis should be placed on the role of the latissimus dorsi, trapezius, deltoid, and biceps. UPPER BACK Bent-Over Row With Barbell SAFETY TIP Always maintain the natural curve in the lower back while performing this exercise, especially if lifting heavier weight. Do not round the back. Execution 1. Stand with legs shoulder-width apart, leaning forward at the waist, knees slightly bent, and arms hanging down, clasped to the barbell with a traditional grip, shoulder-width apart. 2. Pull the barbell to the chest, still in a bent position, until your elbows are bent parallel to the chest. 3. Return the weight to the starting position and repeat. Muscles Involved Primary: latissimus dorsi, trapezius Secondary: triceps, deltoid Running Focus Muscle imbalances are prevalent in runners, predominantly between the four muscles of the quadriceps group, between the quadriceps group and hamstring muscles, and, more generally, between the legs (left versus right). Muscle imbalances of the upper body are often not addressed in strength training for runners because the practical shortcomings of such imbalances are not assumed to affect running performance. However, an imbalance between the “push” muscles of the chest and the “pull” muscles of the upper back can have a dramatic impact on gait because the forward lean or lack thereof changes the degree of lift the quadriceps group can generate during the forward swing phase. A lack of lift as a result of too much forward lean can inhibit the speed of running, especially during faster-paced training. The speed not created by the normal lift of the gait cycle can be compensated for with faster turnover, but the resulting emphasis on aerobic capacity because of poor posture can have an adverse effect on performance if the athlete’s aerobic fitness is subpar. Hence, the anatomy of running plays a major role in performance despite its seemingly secondary role in fitness development. Specifically, if a large muscle group is strengthened (e.g., the pectorals through “push” exercises), the agonist muscles (in this case, those of the upper back) must be equally strengthened. VARIATION Wide-Grip Bent-Over Row With Barbell A wider grip allows you to work the muscle at a different angle. In this case, it does not change the main muscle group worked. Some athletes with longer arms prefer the wider grip because it feels more natural. Maintain the natural curve in the lower back. CHAPTER 6 ARMS AND SHOULDERS Sir Murray Halberg, a New Zealander, won the Olympic 5,000-meter run with a withered arm that was the result of an earlier sporting accident. Even people who lack arms are perfectly capable of running, and often do so very well. However, arms are a necessary part of a smooth running motion; each arm not only aids the balance of the runner, but also assists forward movement by acting as a counterbalance when the opposite leg drives away from the ground. To test this, try leading with your right hand and right leg at the same time—at best, it will feel unnatural; at worst, you will fall over! A further example is to watch a sprinter coming out of the blocks—a high knee lift accompanies exaggerated arm action for the first dozen strides, and then the arms continue to pump away for the rest of the sprint. Distance runners would waste energy by driving the arms in this fashion; as economy of effort to save energy is all-important, so their arms hang fairly loosely, usually with elbows bent to 90 degrees or so with the hands relaxed beyond the wrist joints. Sprinters’ fingers are straight and more tense as they drive each stride, a marked difference, so arms have a serious part to play in successful running, though in distinctly different manners for the type of run being attempted. The arms are attached to the body at the shoulder joint, which is a shallow ball and socket to permit maximum movement through as close to 360 degrees as possible. This is quite effective, although the disadvantage of such mobility is an unstable joint that can be easily damaged. The ligaments that hold the shoulder in place have to be elastic enough to allow movement, so the stability of the joint relies on the strength of the retaining muscles. It may be helpful to have a reminder of Newton’s third law of motion: For every action, there is an equal and opposite reaction. If a muscle contracts and pulls the shoulder in one direction, then one or more other muscles will need to lengthen to allow this to happen. Strong muscles with good tone will tend to separate a joint if those opposing it are weak and undeveloped. This is never truer than with the shoulder joint. The ball of the shoulder joint, at the upper end of the humerus, is located in the shallow glenoid labrum, or cavity, itself a part of the winged scapula that surrounds the posterior portion of the upper chest. From the runner’s point of view, it is beneficial simply to know the muscles that maintain the position of the humeral head (figure 6.1) and which ones can be strengthened to improve running motion. The movement of the legs when they take large strides requires a similarly large movement of the arms backward and forward to balance the action. In sprinting especially, the arms and shoulders play a large part in propulsion, and a sprinter who is losing a race will often tense his or her shoulders as they go backward though the field. Anatomically, strong shoulders aid both strength and balance in the runner, so the exercises that follow are quite as important as those for the lower limbs. Tired arms and tense shoulders lead to a less fluent arm swing and a short stride that then uses unnecessary energy. The endurance that strength training of the upper limbs provides could make the hundredth of a second difference between success and a lifetime of disappointment. Figure 6.1 Upper arm: (a) back and (b) front. The outermost layer is formed by the triangular deltoid muscle. It arises from the clavicle, or collarbone, and part of the top of the scapula to cover the whole joint and be inserted into the middle of the humerus, where its contractions pull the arm out sideways into abduction. It opposes gravity. The complicated pattern of muscles underneath it have developed to enable movement in most planes. This matters little to runners, whose arms merely need to move no more than 45 degrees fore and aft, with minimal sideways movement. These muscles need to be strong rather than elastic. A complicated web holds the arm to the shoulder: The supraspinatus braces the head of the humerus; the infraspinatus, subscapularis, and teres major and minor form a rotator cuff both to connect together and stabilize the shoulder. Below the shoulder are the biceps, triceps, and brachialis muscles. Their primary function is moving the elbow joint, but some fibers are attached around the shoulder, giving even greater stability to that joint. The extensor and flexor muscles of the forearm (figure 6.2) rotate the wrist inward and outward and also move the wrist and fingers. The flexors bend the joints in and the extensors open them out. More detailed knowledge of this anatomy is not the province of the runner, though their strength and flexibility undoubtedly are, so the exercises to promote this are all of relevance in increasing running speed. Once again, any weakness will slow the runner, so the arms, particularly in power sprints, must have endurance equal to that of the legs. This explains why the physique of a sprinter’s upper limbs is not unlike that of a boxer. Evolution has led to the use of arms when running, first to help stabilize the body and then to keep it upright as each leg moves. You should study a steeplechase runner in slow-motion replay to view how the arms help the body prepare for each takeoff, flight, and landing over the hurdles. Second, strong upper limbs not only aid in the production of full power when sprinting but also help the shoulders relax. When the shoulders tense, the runner inevitably slows. In short, a sprinter without arm movement is not a sprinter! One other point to bear in mind is that the legs are unable to run with full efficiency if the arms are not involved in the running action. The effect of this could be that strong legs want to speed up toward the end of a run, but are handicapped by upper limbs that have not been trained for the task. So when the arms fatigue, stride length and rate lessen and the runner slows. Figure 6.2 Forearm: (a) front and (b) back. Specific Training Guidelines While performing biceps exercises, remember to keep your back straight; do not rock to help lift the weight. Choose a weight that does not hinder the smooth motion of the curl, and choose a lighter weight rather than a heavier weight to start. Also, keep your elbows fixed and close to your body, emphasizing the biceps and not the shoulders. Most runners, if they do arm exercises at all, will emphasize the biceps exercises. We have emphasized the triceps to help balance the muscular strength of the arms. Both biceps and triceps exercises can be performed with smaller amounts of resistance. Since distance runners need to be able to swing their arms steadily in the later stages of a long run or race, not to suddenly produce power, the emphasis should be on a larger number of repetitions (18 to 24) because the emphasis is on muscular endurance. For mid-distance runners or sprinters, 8 to 12 repetitions of a heavier weight will suffice. A good order for a sample arm workout would be the narrow-grip barbell curl, double-arm dumbbell kickback, and reverse wrist curl. Alternating Standing Biceps Curl With Dumbbell Execution 1. Stand with feet shoulder-width apart and knees slightly bent. Arms should hang straight down from the shoulders, holding dumbbells with the palms inward. 2. In one smooth motion, concentrating on using the biceps and not the hand, curl one dumbbell upward, completing a full range of motion. 3. Using a slow, fluid movement, lower the dumbbell in the

opposite direction of the curl. Feel the stretch as the dumbbell returns to its starting position. Repeat the exercise with the other arm. Muscles Involved Primary: biceps, brachialis, anterior deltoid Secondary: brachioradialis, flexor carpi radialis TECHNIQUE TIPS ▶ The upper arm should be fixed at the elbow; as the dumbbell passes 90 degrees, the upper arm should not move with it. ▶ Look sideways into a mirror, noting whether the elbow is staying fixed and there is little or no swaying (to aid in focusing on using the biceps brachii). SAFETY TIP This is a simple exercise that can go awry when too much weight is attempted. The ideal weight is heavy enough to provide resistance throughout each rep and set of reps, but not so heavy that poor form eventually occurs. Do not throw the weight by engaging your upper back muscles. The biceps dominates the movement. Running Focus It seems odd that runners need to develop biceps strength. Most distance runners appear emaciated, with thin arms and legs; however, this does not mean that their biceps are not strong. Developing strength is different from adding mass. The biceps exercise, when performed with enough resistance to stimulate strength gains and done with higher repetitions in conjunction with a strenuous running program, will promote functional strength endurance without added mass. Because the goal of the arms, for a distance runner, is to balance the runner from side to side and counterbalance the movements of the legs, the biceps should not fatigue during a grueling training or racing session. Strength endurance is paramount, and performing 12 to 18 repetitions and multiple sets of this exercise will help develop this type of strength. VARIATION Barbell Curl With Variable-Width Grip Barbell curls can be done with a normal shoulder-width grip, a narrow grip, or a wide grip. The narrow grip emphasizes the biceps brachii more than the other grips, while the wide grip incorporates the anterior deltoid (the large muscle encapsulating the shoulder). All three grips are appropriate, and a complete biceps workout can be completed by using just this exercise, incorporating one set of each grip. Alternating Standing Hammer Curl Execution 1. Stand with feet shoulder-width apart. Arms hang straight down from the shoulders, holding dumbbells with the palms inward. 2. In one smooth motion, concentrating on using the biceps, not the hand, curl one dumbbell upward until it touches the shoulder, completing a full range of motion. The upper arm should be fixed at the elbow; as the dumbbell passes 90 degrees, the upper arm should not move with it. 3. Using a slow, fluid movement, lower the dumbbell in the opposite direction of the curl. Feel the stretch as the dumbbell returns to its starting position. Repeat the exercise with the other arm. Muscles Involved Primary: biceps, brachialis Secondary: forearm extensors SAFETY TIP Avoid throwing the weight. Focus on the contraction of the biceps. TECHNIQUE TIPS ▶ The upper arm should be fixed at the elbow; as the dumbbell passes 90 degrees, the upper arm should not move with it. ▶ Look sideways into a mirror, noting whether the elbow is staying fixed and there is little or no swaying (to aid in focusing on using the biceps brachii). Running Focus Similar in execution to the biceps curl—only the hand position is changed—the hammer curl develops strength in the biceps and, to a lesser extent, the brachialis. Performed during the same strength-training session at the end of the biceps set, the hammer curl is a fatigue-inducing exercise that also promotes joint flexibility because of its resistance over a full range of motion. Often, runners complain of sore biceps during and after a race of a shorter duration with more intense effort. Because of the increased force of the arm carriage, a greater demand is placed on the muscles of the upper arm. By performing the biceps exercises, runners can stave off the fatigue during a race and shorten recovery time between reps during a workout. VARIATION Seated Double-Arm Hammer Curl While seated on the edge of a flat bench, feet flat on the floor, back erect, and arms hanging down with a dumbbell in each hand, palms inward, perform the hammer-curl motion with both arms simultaneously. This exercise involves the coordination of both arms, and may cause fatigue a little quicker than when alternating arms. Dumbbell Lying Triceps Extension Execution 1. Lie on a flat bench with both feet on the bench. The torso should be stable. Arms are bent 90 degrees at the elbow, shoulder-width apart. Hold a dumbbell of an appropriate weight with both hands, palms inward. 2. Extend the forearms to full extension. 3. Lower the arms to the initial position slowly, resisting the weight. Muscles Involved Primary: triceps SAFETY TIP Have a spotter place the weight in your hands and hold the weight in place until you begin the exercise. If there is not a spotter, begin the exercise with the arms in the extended position, and perform the negative (lowering the weight) action as the first movement. Running Focus The introduction to this chapter emphasized the importance of the arms in balancing and counterbalancing during running. The triceps exercises listed in this section serve to balance the recommended biceps exercises, creating a well-developed and strengthened upper arm. The muscles of the forearm are involved as secondary movers. The only movement occurs at the elbow joint, precipitated by the engagement of the triceps. VARIATION Barbell Lying Triceps Extension Instead of using a dumbbell, using a barbell to perform the same exercise works well. Execute the exercise the same way, and follow the same safety instructions. Single-Arm Dumbbell Kickback With Bench Execution 1. Kneel on a flat bench with one leg. Keep the spine and torso in a straight line with your head. Establish a stable base of support with the non- weight-bearing hand pressed to the bench, and the opposite-side leg extended with the foot on the floor. The weight-bearing arm is bent at about a 90-degree angle with the palm inward. 2. Extend the forearm backward from the elbow, using the triceps muscles to instigate the movement in a slow, fluid fashion. Keep the elbow in a fixed position parallel to the torso, not higher. Exhale during this motion. 3. Upon straightening the arm, allow the weight to return the arm to 90 degrees by providing gentle resistance. Inhale during the return. Muscles Involved Primary: triceps Secondary: infraspinatus, supraspinatus, deltoid, pectoralis major TECHNIQUE TIP ▶ It is important not to vary elbow position during the exercise. Keep the elbow tight to the body and fixed. Try to avoid dropping the shoulder to help push the weight backward. Running Focus The dumbbell kickback is primarily a triceps exercise, but it recruits the infraspinatus and the supraspinatus muscles of the shoulder. Because the initiation of the arm swing during running takes place in the shoulder, strengthening the triceps and shoulder via this exercise helps ward off arm fatigue and bad posture, two energy-sapping scourges of good performance. VARIATION Double-Arm Dumbbell Kickback The double-arm variation does not require a bench. From a standing position, bend over at the waist so your torso is close to parallel to the floor, feet shoulder-width apart, and grasp a dumbbell in each hand with the arms hanging downward. Perform the kickback movement with both arms simultaneously. The exercise uses the same muscles as the single-arm kickback using a bench, and will incorporate the core muscles of the abdomen and lower back to stabilize the body. Machine Reverse Push-Down Execution 1. Standing with your feet narrower than shoulder-width apart, grasp the short, straight bar attached to a cable (on a pulley attached to the machine) with palms upward (underhand grip). The forearms are extended at approximately 75 degrees to the elbows, which remain fixed at your sides throughout the exercise. 2. In a smooth, uninterrupted motion, push the forearms downward in full extension, keeping the elbows fixed in their original position and close to the body. Exhale throughout the motion. 3. Allow the weight to return to the original position by resisting the pull of the cable gradually and in a smooth manner. Inhale during this part of the exercise. Muscles Involved Primary: triceps, forearm extensors Running Focus The reverse push-down mainly works the triceps, but it has the added benefit of also working the forearm muscles because of the underhand grip. This exercise marks a nice transition from the triceps-dominated extension and kickback into the next exercises, wrist curls, which predominantly work the forearm muscles. The triceps muscles and the extensor muscles of the forearms will fatigue quickly during the exercise as they do during a shorter distance race (5 to 10K), when using the arms becomes a means of propelling the legs during surges and effecting a finishing push. Wrist Curl and Reverse Wrist Curl Execution for Wrist Curl 1. Lean forward on a flat bench with your forearms resting on the bench. The wrists and hands should extend off the bench. Palms should be facing up with a barbell of a light weight resting forward of the palms with the fingers gently closed around the bar. 2. Raise the barbell by raising your hands, involving only the muscles of the forearms and hands, through a full extension. 3. Return the weight to its original position, gradually resisting the barbell as it moves downward. Execution for Reverse Wrist Curl 1. Lean forward on a flat bench with your forearms resting on the bench. The wrists and hands should extend off the bench. Palms should face downward with a barbell of a light weight gripped securely by the palms and fingers. 2. Raise the barbell by raising your hands, involving only the muscles of the forearms and hands, through a full extension. 3. Return the weight to its original position, gradually resisting the barbell as it moves downward. Muscles Involved Primary: forearm flexors, forearm extensors TECHNIQUE TIPS ▶ Focus on a full stretch of the muscles, but do not allow the barbell to snap down. ▶ If it is difficult to rest your forearms on the bench, you can rest them on your legs. Running Focus After gradually incorporating the extensor and flexor muscles into the strength-training routine, use wrist curls and reverse wrist curls to emphasize these muscles. During the course of a four-hour marathon, each arm will swing approximately 22,000 times. Although the movement is initiated by the larger muscles of the shoulders, the upper arms and the forearms are involved in the arm carriage. Specifically, each forearm is held at approximately 90 degrees to the upper arm to counterbalance the action of the opposite-side leg. During the course of 22,000 arm swings and four hours of being held aloft (fighting gravity), fatigue is bound to set in, creating a chain reaction of biomechanical adjustments resulting in poor form and wasted energy. By performing the strength-training exercises for the arms, this fatigue and its chain reaction of bad results can be mitigated, if not eliminated—hence, less wasted energy, and hopefully faster times and better performances. CHAPTER 7 CORE Running for pleasure was a long way down the list of priorities that determined how the pelvis would evolve in humans. The bones that form it are principally in place as a protective structure for the developing fetus, a need not shared by men, in whom a narrower pelvis forms the platform from which the legs unite with the rest of the body parts and have developed to accommodate locomotion. Six major bones form the pelvis, two each of ilium, ischium, and pubis (figure 7.1a). Although these bones are solidly joined to each other with no discernable laxity, each ilium meets the lowest part of the spine, the sacrum, posteriorly at the large sacroiliac joints, where there can be considerable movement. This is most noticeable during childbirth, when hormonal influences cause the ligaments that bind the joint to relax to such an extent that the joint may become subluxed, or partially dislocated, with considerable instability and possible consequences for the female runner. Above the sacrum are the five lumbar vertebrae, which have an important function in keeping the whole skeletal structure stable. As well as these two joints, each pubis is linked at the front by the symphysis pubis at

the lowest point of the abdomen. This is a more solid fibrous connection, but sometimes liable to damage in a slip or fall or as a result of chronic overtraining, for it forms the pivot and point of maximum force and corresponding weakness between the legs and torso. Figure 7.1 Pelvic bones and muscles: (a) bony structures; (b) pelvic floor muscles. On the side of each ilium is a depression that forms the hip, known as a ball-and-socket joint. Its shape has developed in order to combine maximum stability with the greatest possible range of movement. The shoulder is similar but shallower and has a far greater likelihood of dislocation under load. The head of the femur forms the ball; movement of the joint is limited by the bony surrounds of the acetabulum, or socket, and also by the density and elasticity of the surrounding muscles and tendons. If the pelvis is viewed from above as an oval-shaped clock, the two sacroiliac joints are fairly close together at the 11 and 1 o’clock areas, the hips at 4 and 8, and the symphysis at the 6 o’clock site. If one of these joints is moved, then another has to change position to compensate. This becomes important when running, for the pelvis is swung from side to side and twisted during the gait cycle, which has an effect on all the structures in and around it. Forming a floor to the pelvis is the levator ani (figure 7.1b), which, for those with some knowledge of Latin, does just that. It lifts the anus and cradles all the other internal organs that fill the pelvis so that they do not collapse through the pelvic outlet. Weakness of the levator ani will predispose people to degrees of incontinence, and it is a muscle that requires training and toning just like any other. Running increases the pressure inside the abdomen, so any frailty may produce unwanted physical symptoms. The other pelvic muscles have a dual function to stabilize and move the legs from their pivot at the hip joints. The stability is aided by some large ligaments, which are relatively inextensible, though with good breadth of movement. Running from the lumbar vertebrae and the interior of the ilium are the iliopsoas muscles, which pass through the pelvis, forming soft walls for the internal organs, to the inside of the femur below the hip joint. Over the lumbar vertebrae, they are counteracted by the erector spinae muscles, which stabilize the spine externally. The iliopsoas is a strong flexor of the hip and pulls the thigh up toward the abdomen. The bulk of the buttock is formed by the glutei, three layers of muscle that slope down the outside of the back of the ilium at 45 degrees. Contraction of the outer layer, the gluteus maximus, extends and rotates the hip joint outward. It continues down the outside of the thigh as the tensor fasciae latae (see chapter 8 for more about this). The gluteus medius and minimus, underneath it, insert into the top of the femur at the greater trochanter, where their action is to pull the thigh outward, known as abduction, with the hip joint acting as a fulcrum. Runners with low back pain are frequently diagnosed with piriformis syndrome. The piriformis muscle lies alongside the gluteus medius, and pain probably occurs because of its close proximity to and irritation of the sciatic nerve. It both stabilizes and abducts the hip joint. Because the hip joint is so mobile, there have to be groups of muscles to counteract the forces produced by those that originate around and above the pelvis. These primarily pull the hip backward, abduct, and rotate it outward. The opposing muscles are those of the upper leg, which often have more than one function. The hamstrings—semimembranosus, semitendinosus, and biceps femoris—all arise from the lower pubic bone (figure 7.2) and travel down the back of the thigh and behind the knee joint as its flexor (the lower limbs are discussed in more detail in chapter 8). Their upper leg function is to extend the hip backward. The opposite of abduction is adduction, and the three adductors, magnus, longus, and brevis, together with the gracilis, all pull the thighs together. They arise from the inside of the pubis and are inserted along the inner border of the length of the femur. As well as the iliopsoas, the rectus femoris and the other quadriceps muscles also extend over the hip joint, and when contracted, have a flexing action on the femur. Figure 7.2 Lower core through upper leg: (a) back; (b) front. Muscles may be distinct entities, but often merge into one another and when dissected can be difficult to separate. The running action is repetitive, so that muscles with even slightly different functions may oppose each other during the running cycle and actually produce negative frictional forces. Where this may happen, a small fluid-filled sac called a bursa may form, the largest of which is over the greater trochanter, known as a trochanteric bursa. This may become inflamed and sore. Returning to the pelvis and its adjacent organs, the abdomen, unlike the chest, does not have a bony architecture to stabilize it. The vertical height is maintained by the lumbar vertebrae. The responsibility for stability falls to the abdominal contents, which exert a counterpressure to a surrounding circular wall of muscles formed by the rectus abdominis, which extends from the base of the rib cage centrally down to the pubic symphysis and bone (figure 7.3). Outside this and lying diagonally are the external and internal oblique and the transversus abdominis muscles, which have three functions: to abduct and rotate the trunk, to flex the lumbar and lower thoracic vertebrae forward, and to contain the abdomen. When running, these muscles alternately lengthen and shorten as the pelvis moves not only from side to side, but also twists, rises, and falls relative to the surrounding body parts. In addition, they have a function to aid respiration at high rates, working in conjunction with the diaphragm and ribs, which is particularly noticeable if the runner is reduced to panting. Thus, they have multiple roles, all of which may be required at the same time, and will perform better if well and thoroughly trained. Figure 7.3 Rectus abdominis and surrounding muscles. Rather than being active exercisers while running, the lower back muscles and lumbar vertebrae have more of a stabilizing passivity. First and foremost, they must maintain an upright posture, tempered by the need to accommodate for hills, where the upper body must lean backward or forward to counteract gravity upending the runner. The encircling musculature must allow rotation, body lean around corners, and lateral movement on any diagonally sloping surface, so they will contract and expand to maintain this stability. These complex movements have to coexist in conjunction with all the other variations in posture that occur as the legs move, the lungs breathe, and the abdominal contents shift to accommodate ingested fluid and nutrients during the run. Intrinsic strength, particularly of the muscles that surround the lumbar vertebrae, should be considered an essential in every runner because any weakness is liable to escalate into other areas. Specific Training Guidelines For the core exercises that require the movement of body weight only, multiple sets can be performed with many repetitions. All body-weight exercises should be slow and deliberate. Without extra resistance, the emphasis should be less on moving weight and more about perfect movement. High repetitions are a great way for a runner to develop muscular endurance, which benefits long-distance runners; however, strength development to aid power only comes from using heavier resistance. Choosing what weights to use (when applicable) and how many or how few repetitions are to be performed is a function of the goal of the workout, and in the macro sense, the performance goal of the runner. Core exercises should be performed at all stages of the training progression. Since many are body-weight bearing only, requiring no additional load, they can be performed three or four times per week. LOWER BACK AND GLUTES Back Extension Press-Up Execution 1. Lie prone on the ground with arms in the push-up position and legs outstretched. Keep the body rigid and in a straight line. 2. Press up the arms only until the torso is off the ground. Hold this position for 10 to 15 seconds, breathing throughout. 3. Lower the arms, bending at the elbows, and return to the original position. Muscles Involved Primary: erector spinae, gluteus maximus Secondary: hamstrings, rectus abdominis, external oblique, internal oblique Running Focus This a very simple exercise to perform. Not to be confused with a synonym for the push-up, the press-up extension of the lower back helps strengthen the muscles and tendons of the erector spinae, and acts as the antagonist for the rectus abdominis muscle. This exercise both strengthens and stretches the support structure of the sacral and lumbar spine, helping the pelvis rotate and twist properly, and mitigating the forward tilt of the pelvis if too many abdominal strengthening exercises have been performed, leading to an imbalance between the abdominals and muscles of the lower back. Unfortunately, an emphasis on the core exercises can become an emphasis on the abdominals, with little attention paid to the muscles of the lower back and the glutes. Without strong glutes and a supportive lower back, the hamstrings often can’t generate sufficient muscular power despite their having been strengthened properly. Essentially, the strongest muscles are only as strong as the weakest link on the kinetic chain allows. The proper movement of the pelvis is critical in the gait cycle. A misalignment of the pelvis due to muscle imbalances between the abdominal muscles and the muscles of the lower back can cause injuries that impede running performance despite good cardiothoracic fitness. LOWER BACK AND GLUTES Lumbar Hyperextension/ Alternating Arm and Leg Raise Execution 1. Lie prone on the ground with arms and legs outstretched. Keep the body rigid and in a straight line. 2. Raise the left arm and the right leg three to four inches off the ground. Hold this position for 10 to 15 seconds, breathing throughout. 3. Lower the left arm and right leg, and raise the right arm and left leg simultaneously. Muscles Involved Primary: erector spinae, gluteus maximus Secondary: hamstrings, rectus abdominis, external oblique, internal oblique TECHNIQUE TIPS ▶ This exercise can also be performed on a Roman chair, where gravity plays a greater resistance role. Because Roman chairs are rarely around when you need them, performing this exercise on the ground works as well. ▶ All the movement should be generated by the muscles of the lower back and glutes. SAFETY TIP Performing this exercise requires hyperextension of the back. Normally, this is not a problem, but for runners with chronic back pain or disc issues, press-ups are safer. Running Focus Lumbar hyperextensions can be performed in many ways. The goal of the lumbar extension is to strengthen and stretch the muscles of the lower back, glutes, and, to a lesser extent, the abdominals to help provide the appropriate pelvic tilt during the running gait cycle. A misaligned pelvis causes a chain reaction of misalignment, resulting in poor running form and wasted energy. Not only do the muscles of the back, abdominals, and glutes have to work in unison, but they also must work to balance each other and still generate enough strength to perform the exercise. This is very similar to how the core works when running. Because the pelvis is rotating and twisting, the core must dynamically stabilize, reacting to terrain shifts, turns, and missteps. VARIATION Lumbar Hyperextension on Physioball Using a physioball changes the dynamic of the lumbar hyperextension. By only using one hand for balance (and, after mastery, no hands), there is a neuromuscular (proprioceptive) component added to the exercise. Ultimately, the goal of this exercise is to not include a balance hand. Balance can be maintained on the physioball from mastering the form of the exercise and strengthening the muscles of the core so that they can be activated when needed. Runners tend to overlook proprioceptive exercises because there is not much visible effort, rather small, subtle movements that help create more fluid running. LOWER BACK AND GLUTES Hip

Abductor Machine Execution 1. Sit in a proper seat position, with machine pads on the outsides of the knees. 2. Press outward using the abductor muscles (outsides of the legs). Emphasize reaching a full range of motion. 3. Return to the original position by gradually resisting the weight. Muscles Involved Primary: gluteus medius, gluteus maximus Secondary: tensor fasciae latae, quadriceps TECHNIQUE TIPS ▶ The motion should be fluid, but with consistent effort throughout. ▶ The more upright the backrest, the more the emphasis on the gluteus medius. ▶ Avoid trying to overextend the exercise. Don’t force the legs higher laterally than your hip naturally allows. Focus on pressing the legs apart using only the targeted muscles of the gluteus. Running Focus The abductor exercise can be done during the same workout as the adductor exercise; it is easy to change the pad positions on the machine, but its emphasis on the glutes makes it a better fit with the exercises for the glutes and lower back. Many runners, especially those who underpronate, complain of piriformis pain at some point in their running careers. Because of its location, the piriformis muscle is difficult to stretch. However, abduction exercises aid in preventing and treating piriformis pain and sciatica by stretching and strengthening the gluteus medius, which is connected. ABDOMINALS AND PELVIS Floor Sit-Up Execution 1. Lie on the back with knees steepled, feet pressed to the floor, and hands gently touching the back of the head, but not clasped. 2. Raise the torso by rounding the back one vertebra at a time while pressing the pelvis down to floor. Raise the torso only 45 degrees before lowering the back to the floor. 3. Inhale, and gradually lower the torso to the floor one vertebra at a time. Muscles Involved Primary: rectus abdominis, external oblique Secondary: quadriceps, tensor fasciae latae TECHNIQUE TIP ▶ Sit-ups can be performed with a partner holding down the feet of the person performing the exercise. It makes the exercise easier, but allows more reps to be performed. SAFETY TIP Don’t clasp, but gently touch the hands behind the head because it is easy to pull the head and torso up by using the muscles of the arms. Running Focus Because the quadriceps and hamstrings counterbalance each other, so do the muscles of the abdominals and lower back. To avoid muscle imbalances and potential injury, it is important to perform abdominal exercises after performing the strength-training exercises for the lower back described in the first part of this chapter. The sit-up should not be performed for speed, but in a relatively quick, fluid manner. The lowering of the torso should be done slowly, with attention to the work the abdominals are doing. The rectus abdominis is the dominant muscle affected by sit-ups. It controls the flexion of the abdomen. Because almost all abdominal exercises work the rectus abdominis, a single set to failure can make up the start of an abdominal set. The proper movement of the pelvis is critical to the gait cycle. A misalignment of the pelvis due to muscle imbalances between the abdominal muscles and the muscles of the lower back can cause injuries that impede running performance despite good cardiothoracic fitness. VARIATION Oblique Twist A simple variation on the sit-up involves twisting the torso using the oblique muscles by attempting to touch the elbow to the opposite hip. A set of 12 can be done all on one side and then the other, or each rep can alternate sides. ABDOMINALS AND PELVIS Hanging Leg Raise SAFETY TIP This exercise can put a lot of stress on the shoulder. Limit the number of reps if the shoulder is compromised. Execution 1. Hang from a pull-up bar with palms facing forward. Emphasize lengthening, feeling gravity exerting its force on your spine. 2. Using a controlled movement, bring the knees up toward the chest. Keep the torso from swinging. 3. Gradually return to full extension and continue to repeat. Muscles Involved Primary: rectus abdominis, external oblique, iliopsoas Secondary: latissimus dorsi, serratus anterior Running Focus The hip flexor muscles, specifically the iliopsoas, fatigue greatly during the course of a long run or race on a course that has the same terrain throughout. The repetitive nature of running is exacerbated with few terrain changes, and smaller muscles fatigue quickly. By strengthening the iliopsoas and the other hip flexors, runners can delay the onset of this fatigue. Also, when the terrain is hilly, requiring a lot of lifting throughout a run, weaker muscles will fatigue quicker, and gaining solid footing becomes harder. VARIATION Hanging Leg Raise With Twist The standard hanging leg raise affects the external and internal oblique, but adding a twist to the side increases the role of these abdominal muscles that are responsible for rotation and lateral flexion of the torso. As was mentioned in the introduction to this chapter, the oblique muscles help to twist, allowing for terrain adjustments, and they aid respiration by working in conjunction with the diaphragm and ribs. ABDOMINALS AND PELVIS Dumbbell Side Bend Execution 1. Stand with good posture, feet shoulder-width apart. Hold a dumbbell in one hand with the arm extended downward. The other hand is placed behind the head with the elbow out. 2. Bend at the waist in the direction of the hand holding the dumbbell, allowing the weight to pull the side down gradually. 3. Complete a set of 12 reps and then switch the dumbbell to the other hand and repeat. Muscles Involved Primary: external oblique Secondary: rectus abdominis, quadratus lumborum Running Focus Balancing the abdominal muscles is the goal of this exercise. Most abdominal exercises focus on the large muscle of the abdominals, the rectus abdominis. The side-to-side movement of this exercise helps develop the external oblique, also strengthened in the hanging leg raise with twist. The strengthening of the external oblique helps minimize the side-to-side listing at the end of a fast race or hard effort in a speed workout. Because the smaller muscles of a large muscle group—that is, the abdominals—fatigue easier than the large rectus abdominis, it is important to do exercises that specifically target the smaller muscles so that they maintain their relative strength and do not become dominated by the larger muscle. The practical application of this exercise is to eliminate the side-to-side rocking of the upper body during the gait cycle. While a leg length discrepancy could cause this rocking, the usual culprit is poor abdominal strength, especially weak oblique muscles. The inability of the abdominal muscles to maintain erect posture causes an awkward side-to-side motion generated by a pelvis that is not aligned. ABDOMINALS AND PELVIS Single-Leg V-Up Execution 1. Lie flat on the back with your hands reaching back behind your head. One leg is steepled and the other is raised approximately six inches off of the ground. 2. Leading with the chin and chest, engage the abdominals, raising up as in a sit-up, but also raise the leg that is off the ground, meeting the hand at its apex. 3. Recline to the initial position. Muscles Involved Primary: rectus abdominis, transversus abdominis, iliopsoas Secondary: hamstrings, gluteus maximus Running Focus This exercise is dynamic and quickly fatigues the abdominal muscles and the iliopsoas. Because of the incorporation of both the upper body and lower body, there is more of a whole-body movement that more closely resembles a running movement than some of the other exercises in this chapter. Performed to failure, this exercise and its variation with a medicine ball can be an entire abdominal workout, especially if done as the final exercise in a strength-training session. VARIATION Single-Leg V-Up With Medicine Ball The use of the medicine ball works the abdominals harder because of the added weight. Since the medicine ball is held away from the abdominals, even a five-pound ball feels heavy as a result of its distance from the fulcrum (the abdominal muscles). Also, the coordination of the movement with the added weight helps develop coordination, a skill not gained when just running in a forward motion. CHAPTER 8 UPPER LEGS There is no real division between the core and the upper leg; all the limbs merge seamlessly into each other. Some of the pelvic muscles help movement and stability of the leg, and vice versa. The same occurs at the knee, where muscles are described as crossing over two joints, so they influence the action and steadiness of the joints. The upper leg (figure 8.1), or femur, is inserted via the hip joint into the pubis and ischium. The other bone of the upper leg, the patella (knee joint), is really a pulley. It runs in a groove at the lower end of the femur to help guide the extending forces of the quadriceps muscles around the knee. Figure 8.1 Bony structures of the upper leg. The primary function of the quadriceps group (figure 8.2a) is to extend the knee. From the outside to the center line, the vastus lateralis, rectus femoris, vastus intermedius, and vastus medialis combine at the superior pole of the patella and straighten the knee joint with a pull through the patellar tendon on the upper part of the tibia. Contraction of this, the largest muscle group in the body, also pulls the knee toward the chest. It is particularly relevant to the sprinter, who gains extra stride length with big quadriceps contractions; however, this high knee lift wastes energy in a long-distance run, so the hip and knee have much smaller ranges of motion when covering longer distances. The role of the quadriceps in the running action is therefore twofold, though the intent of both movements is to increase the stride length (see figure 3.2 on page 23). If at the same time the knee is fully extended and the quadriceps muscles exert the maximum flexion to the hip, not only is the stride length maximized, but the added time in the air will also allow the momentum already generated to propel the body farther forward. Much the same goes for the hamstring muscles (figure 8.2b), which also span the two joints but act in an opposite manner to both extend the hip and flex the knee. The semimembranosus, semitendinosus, and biceps femoris have some congruity in the center of their bulk, having arisen from different points within the pelvis, but then separate behind the knee and are inserted into the rear of the tibia and fibula. Contraction of the hamstrings drives both the upper and lower leg backward, a movement that tends to be exaggerated in a sprinter (see figures 3.3 and 3.4 on pages 24 and 25). Increased knee flexion would be inefficient to a distance runner; a greater percentage of the hamstring motion for a distance runner occurs at the hip. It may be helpful to consider each full hamstrings group as two separate half muscles. This may sound paradoxical, but although it is the upper portion that links over the hip joint as an extensor muscle, the lower portion both flexes and limits extension of the knee. There is, of course, no actual physical distinction within the muscle groups when they are microscopically examined; the difference is purely functional. In the distance runner the hamstrings have a limited range of motion over both the hip and knee joint, although their contraction is very powerful over these small angles. Figure 8.2 Upper leg: (a) front and (b) back. It may seem strange that the knee needs to be able to twist, but how else would a runner turn corners or cope with uneven terrain? The knee (figure 8.3) has two collateral ligaments on the inside and outside that allow it to hinge to and fro, but rotation depends on the half-moon-shaped menisci, also known as cartilages, which are placed between femur and tibia and spread weight through the knee joint. They also allow the bones to twist on each other. An anterior and posterior cruciate ligament within each knee, placed in a crosslike shape, obstruct excessive forward and backward movement of femur and tibia on each other. It should be stressed, however, that these ligaments are there to guide knee movement and play only a small part in maintenance of knee stability, which depends mostly on the strength of the muscles. The thigh muscles

need both strength and flexibility, each of which can be improved by exercise. The maintenance of a balance between the two is also vitally important because being muscle-bound will do little for pliability; the converse is equally true in that lack of muscle bulk will cause relative weakness. Figure 8.3 Knee ligaments and tissue. Specific Training Guidelines Protection of the knee joint while performing some of the following upper leg exercises is an important consideration. Because both the quadriceps and hamstrings groups of muscles attach to the knee, and the knee joint twists to adapt to terrain variations, turns, uphills, and downhills, there is constant stabilization and relaxation of the joint. The lunge exercises are difficult to perform initially, so care must be taken to perfect the motion with lighter weight before increasing the resistance. A machine-aided exercise helps protect the joint, but it has a fixed range of motion that does not make it the best functional exercise. The exercises listed for the upper legs are good introductory and strength (threshold) phase exercises. However, they should not be done during the final phase of training, which emphasizes V O2 max. During the final phase, substitute the plyometric exercises listed in chapter 12 to meet a runner’s needs without overly fatiguing the muscles. ADDUCTOR FOCUS Hip Adductor Machine Execution 1. Sit in a proper seat position, with machine pads on the insides of the knees. 2. Squeeze inward on the pads. The motion should be fluid but with consistent effort throughout. 3. Return to the original position by gradually resisting the weight. Muscles Involved Primary: adductor longus, adductor brevis, adductor magnus, gracilis Secondary: vastus medialis TECHNIQUE TIP ▶ Avoid pushing the weight with the feet. Focus on bringing the legs together with the adductor muscles. Running Focus The adductor exercise can be used in a strength-development regimen or as a rehabilitative regimen that requires ancillary muscles to be developed without undue stress on the knee joints. Many knee problems are caused by an imbalance of the four quadriceps muscles, which cause tracking issues for the patella. The adductor exercise strengthens the adductor muscle group specifically and the vastus medialis secondarily, preventing the patella from tracking too laterally. Developing strength in the adductor group and the quadriceps muscles of the upper leg aids in the powerful extension during the propulsive phase of the running gait. To prevent imbalances in the quadriceps, perform the abductor exercise on the same piece of equipment, as described in chapter 7. QUADRICEPS FOCUS Machine Leg Extension Execution 1. Sit in the leg extension machine in the appropriate position. Keep the knees in line with the fulcrum of the weight lever and the back straight. Grasp the handles on both sides of the seat, but do not squeeze. 2. After choosing an appropriate weight, extend, but do not hyperextend, both legs through a full range of motion with a fluid motion. 3. At full extension, lower the legs gradually, resisting the weight while inhaling deeply. Muscles Involved Primary: quadriceps Secondary: tensor fasciae latae, sartorius TECHNIQUE TIP ▶ Avoid hyperextending the knees and rocking the body to help lift the weight. Running Focus The machine leg extension is a fantastic exercise because it is simple to perform and has a great impact on quadriceps strength. It develops the four muscles of the quadriceps equally (rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius) and aids in keeping the patella tracking correctly. For runners suffering from a patellofemoral injury, the full extension needed for this exercise will unduly stress the patella. To help develop the quadriceps, a modified version of the exercise using a short arc (only the final 15 to 20 degrees of the exercise) helps off-load the patella. This exercise is a must during the introductory phase of training due to its general strength-building power. VARIATION Machine Leg Extension With Short Arc The leg extension with short arc variation is an excellent exercise for developing quadriceps strength if there is knee pain due to patellofemoral syndrome. The only drawback is that it is not a full range-of-motion exercise; however, once the knee pain dissipates, the full extension exercise can be completed. HAMSTRING FOCUS Machine Lying Hamstring Curl Execution 1. Lie prone on a hamstring curl machine. The pads of the machine are situated at the Achilles tendon. Hands are outstretched, holding onto the handles of the bench. Keep the head centered with the chin slightly off the bench. 2. Focusing on the hamstring muscles, slowly but fluidly pull the weight upward. 3. Return the weight to the starting position by gradually resisting the downward motion of the lever. Muscles Involved Primary: hamstrings Secondary: gluteus maximus, gluteus minimus, gastrocnemius SAFETY TIP Some common mistakes made while performing this exercise are pulling strongly on the handles to help aid the motion of the exercise, lowering the weight too quickly, and slamming the weight into the glutes to finish the repetition. Running Focus As the counterpart to the machine leg extension, the lying hamstring curl works the large muscles of the hamstrings, helping to balance the quadriceps muscles of the front of the leg. The hamstrings come into play during the recovery phase of the gait cycle, as the lower leg bends at the knee, pulling the leg upward toward the glutes. The hamstrings group is not as strong as the quadriceps group, but it must be diligently strengthened or an imbalance between the quadriceps and hamstrings could occur. It is not common for distance runners to experience hamstring tears or pulls, but it is common for distance runners to suffer from hamstring tightness because of problems in the lower back. Also, many knee injuries are related to weak hamstrings. One complaint about the hamstring curl is that it works only the hamstrings and not the hamstrings and glutes, which work together in the gait cycle. While true, this is less significant if the exercise is performed in the base, or introductory, phase of training, where the emphasis is more on general strengthening and less on functional work, and where other exercises can work the glutes. Dumbbell Lunge Execution 1. Stand with legs shoulder-width apart, with good posture. Each hand is holding a dumbbell that is relatively light. 2. Take a small step forward with one leg, lowering your hips as you step so that your quadriceps are parallel to the ground and your lower leg is at a 90-degree angle at the knee. Your rear leg provides balance. 3. Return to the original position by pushing upward, after reaching parallel, with the same leg that made the initial step. Repeat the exercise for a full set of reps on one leg, or switch legs after a rep with each leg. Muscles Involved Primary: quadriceps, hamstrings, gluteus maximus Secondary: rectus abdominis, external oblique SAFETY TIP One caution for this exercise is to not allow the kneecap to extend past the toes of the lead foot while performing the movement. The possibility of injuring the knee because of its relatively vulnerable, unstable position while performing a difficult, anaerobic exercise is real. This is a wise rule to follow for most people; however, in a few runners with longer femurs, it is difficult not to extend past the toes. Practice the exercise in front of a mirror, and if your form is spot-on and your knees extend past your toes, so be it. Running Focus The lunge is a difficult exercise to master quickly. Like the squat, a similar movement, it develops strength throughout the core, hamstrings, and quadriceps, but mastering the proper form is difficult. It is important to master the technique before adding weight. A barbell instead of dumbbells can be used, but holding the barbell on the shoulders is an unnatural hand position for a runner. Keeping the hands low while holding the dumbbells is normally more comfortable for runners. This exercise fits nicely in the second, or strength (threshold), phase of training. It is functional and, with the added weight of the dumbbells, can develop significant strength. VARIATION Lunge With Long Step By taking a longer step, the gluteus medius and gluteus maximus of the leg that is forward are strengthened more than with a regular step, and the iliopsoas and rectus femoris of the back leg are stretched. Machine Incline Leg Press Execution 1. Sit with the feet placed close together (narrower than shoulder-width apart) on the bottom part of the footplate. The back and the head are pressed against the back pads. The safety catch should be on. Flip the safety outward, rendering the weight active. The legs should be prepared to support the weight before the safety is released. Inhale. 2. Concentrating on the hips, glutes, and quads, extend the legs in a fluid movement to full extension by extending both knees. 3. Return to the starting position by gradually flexing the knees, allowing the weight to slowly lower back to the original position. Muscles Involved Primary: quadriceps, gluteus maximus Secondary: gastrocnemius, biceps femoris SAFETY TIP This exercise allows for a greater weight to be used because of its reliance on a machine; however, be careful not to add too much weight until proper form is established. TECHNIQUE TIP ▶ Do not hurry the movement, which results in the weight moving past the full range of motion and bouncing back to the legs. Running Focus The machine incline leg press is a safe exercise to perform, and it can increase strength in the quadriceps and glutes quickly because relatively heavy weights can be used because of the incorporation of the machine. Instead of using energy and strength by heavily incorporating stabilizing muscles (abdominals and adductors), the exercise effectively isolates the quads and glutes, strengthening both sides of the upper leg, helping to avoid muscle imbalances and potential injury. Altering foot position on the footplate will change the muscle groups impacted. To incorporate more of the glutes, place your feet at the top of the footplate. Due to its emphasis on the large muscle groups, this exercise creates explosive power for runners. Therefore, it is best used by runners training for shorter events such as a 5K or for track racing in sprints or middle-distance events. The exercise is suitable during the introductory phase of training for all runners because it is a general strength exercise, not a functionally-specific strength exercise. Bent-Leg Good Morning Execution 1. Stand with good posture, feet shoulder-width apart, grasping a barbell of light weight across the shoulders. 2. Lower the torso by bowing at the waist. The back should be lowered in a single plane, maintaining the lumbar (lower back) curvature. The glutes push outward during the motion. Inhale during the downward movement. 3. Return to the standing position by raising the torso, focusing on the rotation of the pelvis. Muscles Involved Primary: hamstrings, gluteus maximus Secondary: gastrocnemius, external oblique, internal oblique Running Focus Many distance runners complain that they feel chronic tightness in the lower back because of the accumulated mileage they have run in training. The jarring impact of a heel strike plus a lack of flexibility has caused many a runner to discontinue training and find another sport. How can you alleviate such a problem? Exercises like the bent-leg good morning, which actually strengthens and stretches the hamstrings in one exercise, work well. Again, like most of the exercises in this book, the bent-leg good morning is a simple exercise to perform, and it has multiple benefits. Aside from strengthening the hamstrings and glutes, it also helps stretch these muscles, helping to loosen the connective tissue between the muscles and the bones of the lower back and the pelvis. This kinetic chain also affects the knees because a more supple lower back pulls less on the hamstrings, in turn allowing the kneecaps to track normally. VARIATION Straight-Leg Good Morning The good morning can be performed with straight legs, but runners with chronically tight hamstrings should perform the exercise with bent legs because of the emphasis on hamstring flexibility. Once greater flexibility is attained, the straight-leg version can be incorporated. Dumbbell Romanian Deadlift Execution 1. Stand with feet slightly apart and legs slightly bent, with each arm extended downward holding a dumbbell with an overhand grip. There is a slight natural curve in the lower back. 2.

Gradually bend at the waist, lowering your back in a single plane while maintaining the natural curve in the back, with the dumbbells almost scraping the quads and knees as you bend. 3. Return to the upright position once you can no longer lower the weight. Muscles Involved Primary: hamstrings, gluteus maximus Secondary: erector spinae TECHNIQUE TIP ▶ The dumbbells should not reach the floor. The slight curve in the lower back should prevent that much movement. Running Focus This intense exercise emphasizes the upper legs, specifically the hamstrings and glutes. It is extremely functional in that it works the muscles the way they work when running, more so than the hamstring curl. As has been noted previously, the balance between the larger quadriceps group and the hamstrings is the key to extension and propulsion during the gait cycle. To ensure uninterrupted training, avoidance of injury can be almost guaranteed by performing exercises like the dumbbell Romanian deadlift that help stretch and strengthen the back of the upper legs. Also, given the demands of fast-paced running on the hamstrings, fast-twitch muscle fibers of the hamstrings are best trained with higher-intensity exercises like the dumbbell Romanian deadlift. Squat Execution 1. Using a squat rack, slide under the barbell and center the barbell on the deltoid and trapezius muscles, not the vertebrae of the neck. Feet should be shoulder-width apart and splayed slightly. 2. Inhale deeply, expanding the chest. Maintain the natural curve in the lower back while straightening up and lifting the barbell off the rack. 3. Establish proper position by taking a few steps backward, repositioning the feet and reestablishing the accentuated curve in the lower back. 4. Look toward a point above head level, and initiate the squat action by bending forward at the hips, which will lower the rear. When the thighs are parallel to the floor, straighten the legs and return to the initial position while exhaling. Muscles Involved Primary: quadriceps, gluteus maximus, gluteus medius, gluteus minimus Secondary: hamstrings, external oblique, gastrocnemius Running Focus The squat is primarily a quadriceps exercise, but because of its stability demand, it also helps strengthen the core, hamstrings, and muscles of the lower leg. Heavy weight can be lifted, but it is not necessary to make this exercise effective. Squats should be performed during the same session as the dumbbell Romanian deadlift or the good morning to create balance between the front and back of the legs. Like the machine incline leg press, the squat creates explosive power due to its emphasis on the large muscle groups. Therefore, it is best suited for runners training for shorter events such as the 5K or for track racing in the sprints or middle distance events. Because it is a general strength exercise, not a functionally-specific strength exercise, it is suitable during the introductory phase for all runners. Its emphasis on core stability can aid all runners at every phase of the training progression. VARIATION Single-Leg Squat With Dumbbells This exercise aids in developing the adductor muscles of the inner thigh. Stand about two to three feet in front of a bench with a dumbbell in each hand. Place the top of one foot (laces of the shoe down) on the bench behind you. Lower your body until the forward leg is bent 90 degrees at the knee and the knee of the rear leg is almost touching the ground. Push back up using the quadriceps muscles of the forward leg. After performing a set of 12 on one leg, switch legs. The weight of the dumbbells does not need to be heavy. Initially, until good form is established, no added weight is necessary. CHAPTER 9 LOWER LEGS AND FEET Any structure that will pass the test of longevity must have a strong, secure, and preferably wide base. The human being is certainly not a pyramid, which is the perfect example of such a design, yet to remain upright the human has to survive with two stable lower limbs, augmented by relatively large feet, over a fairly narrow base. The tibia (figure 9.1) is the major weight-bearing bone of the lower leg. It is splinted by the thinner fibula, which becomes more relevant at the ankle, where it forms the outer part of this hinged and curved joint. The muscles attached to these bones control the movement of both the ankle and the metatarsals and phalanges that form the foot. The ankle joint itself moves almost entirely in the anterior-to-posterior plane, but the seven bones that form the tarsus are placed so that there can be both inversion and eversion of the foot at the midtarsal and subtalar joints. This allows each foot to turn inward and outward to accommodate for uneven or slippery ground underfoot. Figure 9.1 Bony structures and soft tissues of the lower leg and foot. Only three bones on the undersurface of the foot make contact with the ground. Under the heel is the calcaneum, and the first and fifth metatarsal heads complete the triangle. Between this tripod of bones is a complex consisting of the talus, cuboid, navicular, and three cuneiform bones, which lie in opposition to each other in such a way that they can be raised to form a longitudinal, or lengthwise, arch to each foot with the five metatarsal bones. Not only do they have to change position to compensate for variations underfoot, but they also allow the feet sideways movement. The tarsal bones form the apex of a bony arch, and when viewed from the ends of the toes appear to rotate on each other to enable the feet to move in or out. It is by this movement that walking or running on the inside or outside of the feet is possible. The power from the calves to push forward comes from the two muscles of the posterior compartment (figure 9.2). The soleus is the deeper muscle and combines with the gastrocnemius to form the Achilles tendon, which is inserted into the calcaneum. Their contraction pulls this bone and thus the whole foot backward. A deeper layer of muscles provides flexion to the metatarsals and toes. These are the flexor digitorum longus, flexor hallucis longus, and tibialis posterior. They provide plantarflexion to the foot and, because they cross several joints, to the ankle as well. The anterior, or extensor, compartment of the leg lies between the tibia and fibula and is surrounded by a relatively inelastic fibrous sheath. Within it are contained the tibialis anterior, extensor digitorum longus, and extensor hallucis longus muscles. These pass through the front of the ankle and are inserted into the tarsal, metatarsal, and toe bones in order to raise them or lift them up, an action known as dorsiflexion. These do not have to generate the same power as the posterior calf muscles for most activities, so they are less developed and weaker. Further lateral stability to the ankle and rear foot is provided by the peroneal muscles, which arise from the fibula and pass around the lateral side of the ankle joint to be inserted into the outer metatarsals. Very powerful forces are generated through the Achilles tendon. If it is injured, it tends to be very painful because of its well-developed nerve supply and heals slowly because of poor blood flow. Much the same can be said of the plantar tendon, or fascia, which spreads from the front of the calcaneum and is inserted at the bases of the five metatarsals. It is an unyielding sheet of fibrous tissue whose weakest point is at the heel. If the foot is viewed two- dimensionally from the inside, the plantar tendon provides the horizontal base to the triangle completed by the tarsal and metatarsal bones. Figure 9.2 Lower leg and foot: (a) back and (b) front. This anatomy must be considered on a functional basis, and watching a slow-motion recording of a foot landing and taking off is invaluable in understanding the motion involved in each stride. The initial plant of the foot is known as the heel strike, after which the foot turns a little inward, with the weight of the body progressively passing down the outer side of the foot before landing is completed on the ball formed by the metatarsal bases. Fewer runners meet the ground first with their toes, sometimes because of an inability to dorsiflex sufficiently. This lack of heel strike may be due to genetic or structural causes. Most people can run on their toes only for a very short time and distance because the work of plantarflexion is taken over by the comparatively weak toe flexors rather than the powerful calf muscles working through the pivot of the calcaneum, especially if dorsiflexion is limited. Once the foot is flat, the movement continues in reverse; during takeoff, the heel lifts off first, rolls inward along the outer metatarsals, and ends with the final push-off from the ball of the foot. During this action, all the muscles will contract or expand in a regular rhythm, though not at the same time. At this juncture we need to demystify the superstitions that have developed around feet that are pronated or supinated. There are three related but separate elements to movement within the foot. At the subtalar joint, the foot inverts and everts, or turns inwardly or outwardly. At the midfoot, there is abduction or adduction, where the movement is solely in the horizontal plane, while at the forefoot, the movement is principally up and down, in dorsiflexion, which somewhat confusingly describes an extension of the foot, or plantarflexion. Pronation describes a compound movement of these joints, where there is eversion at the subtalar joint, abduction (i.e., outward horizontal movement) at the midfoot, and dorsiflexion at the forefoot. Supination describes the opposite movement of each joint. Every foot, with every stride, exhibits some of these actions. When they become excessive, the runner may have difficulties that lead to pain or injury. Excessive pronation when the foot is flat on the ground, where the longitudinal arch of the foot leans excessively inward and the toes point outward, will stress the tibia by internally rotating it and the ligaments between the bones of the midfoot by stretching them, affecting the ability of the inverting muscles of the feet to perform efficiently. Supination describes the opposite action, in which the outside of the runner’s foot takes the weight of landing on the ground. The tibia is disproportionately externally rotated, and the effect of the extra strain on the peroneal muscles may also spread to the iliotibial band. (In chapter 11 we demonstrate how appropriate footwear may minimize the distress that overpronation and supination may pose to the serious runner.) Because of the strains imposed when the feet are excessively overmobile, a severely supinated foot may prove too much of a handicap for a distance runner, though many of the fastest runners in the world have overcome this potential disability. Another anatomical variation concerns those with high, rigid, longitudinal arches, who may also but not necessarily supinate, and those with flat arches with or without excessive pronation. For both of these types of feet, the lack of flexibility is likely to lead to a mechanical disadvantage in that they may be slower runners than they otherwise might. Specific Training Guidelines Some of the standing exercises are performed or can be performed unilaterally, meaning one leg at a time. This type of movement can significantly strengthen the targeted muscles by recruiting all the major leg muscles, weaker ones included, to establish balance while properly performing each exercise. As mentioned in chapter 5 and thoroughly examined in chapter 7, exercises that require stability engage the core muscles of the abdomen, lower back, and hips to maintain proper form. Performing most freestanding exercises unilaterally helps ensure that the specific muscles targeted plus the core muscles recruited develop strength and, with enough reps, muscular endurance. CALF AND ACHILLES Single-Leg Heel Raise With Dumbbells Execution 1. Stand on a platform with one foot touching the platform with only the ball of the foot and the toes. The midfoot and the heel are not touching the platform. Hold the other leg at a 90-degree angle at the knee, from the hip, not touching the platform. Both hands should be holding dumbbells, with the

arms extending straight down along the hips and sides of the quadriceps. 2. Maintaining proper posture, an erect upper body stabilized by the engagement of the abdominal muscles, rise up (plantarflexion) on the foot on the platform. Do not hyperextend the knee. The leg should be straight or slightly bent at approximately 5 degrees. 3. Lower the foot (dorsiflexion) back to the beginning position. Complete to tolerance each set and then repeat the exercise using the other leg. Muscles Involved Primary: gastrocnemius, soleus Secondary: tibialis anterior, peroneus brevis, flexor digitorum longus Soft Tissue Involved Primary: Achilles tendon TECHNIQUE TIP ▶ The exercise should be performed until the calf muscles begin to burn. Do not perform to fatigue unless performing only one set. One to three sets will suffice, with the amount of weight held being a variable that can change the effect of the workout. Running Focus The single-leg heel raise exercise should be a staple of every runner’s strength-training regimen because it is a simply-performed exercise with very little equipment, and because it is a multipurpose exercise. Specifically, it can be performed to develop strength, which aids in injury prevention, and it can be used as a rehabilitation exercise if the Achilles tendon or calf muscles have been injured. The exercise should not be performed if a runner is still suffering the initial effects of the injury, but can be safely performed after the onset of the injury if some healing, determined by a subjective evaluation of the pain level or the evaluation of an objective image (MRI), has taken place. As described in chapter 10, adding an eccentric, or negative, component of the exercise (lengthening of the muscle) adds value to this specific calf and Achilles tendon exercise. Eccentric motions have value because the muscle can handle a lot more weight eccentrically contracting. It is also hypothesized that muscle strengthening is greatest when performing eccentric-contraction movements and that eccentric contractions are better suited to develop a muscle’s fast-twitch fibers. CALF AND ACHILLES Machine Standing Heel Raise TECHNIQUE TIP ▶ The upper body should be erect and the abdominal muscles should be engaged to maintain proper form. Execution 1. Stand under the shoulder pads of the machine so that there is a small amount of flex at the knees. The upper body should be erect and the abdominal muscles should be engaged to maintain proper form. Arms should be placed on the handles next to the shoulder pads. A light grip should be used. 2. Elevate the heels (plantarflexion) until both feet are only touching the platform with the metatarsals and toes; however, the toes should be relaxed and the emphasis should be on the extension of the calf muscles. 3. Lower the heels until a full stretch of the calves is felt. Repeat. Muscles Involved Primary: gastrocnemius, soleus Secondary: tibialis anterior, peroneus brevis Soft Tissue Involved Primary: Achilles tendon Running Focus The standing heel raise is another exercise designed to strengthen the complex of calf muscles (gastrocnemius and soleus) and the Achilles tendon. Its emphasis is more on the gastrocnemius, the larger portion of the calf, than the soleus, but it does work the smaller muscle also. This exercise can be done during the same workout as the single-leg heel raise to really fatigue the calf muscles, or it can be done independently of the other exercises when the goal of the workout is to perform one exercise per body part. The Achilles tendon and calf muscles take on much of the shock absorption and deflection after heel strike. When a runner races in lightweight shoes with a lower heel height than traditional trainers, the impact becomes more pronounced. To help minimize impact and aid in propulsion by moving the foot through its cycle, all runners should include exercises to develop calf strength in their training. These exercises can be performed during any stage of the running progression, with special emphasis during the racing phase if no injury has occurred. VARIATION Machine Seated Heel Raise Similarities between the anatomy affected by the standing heel raise and seated heel raise abound, but it is the emphasis on the soleus muscle that differentiates the two exercises. When sitting, the gastrocnemius muscle is less involved in the exercise, allowing the soleus, despite its smaller size, to become the dominant calf muscle. The strengthening of the soleus aids in the propulsive force of the takeoff phase of the running gait cycle. It also aids the runner who races (or works out) in racing flats to overcome calf pain and Achilles tendon strain during and following a race or a workout. The lower heel height of the flat or spike forces the Achilles tendon to stretch more than in running shoes. A strengthened and stretched soleus muscle helps prevent injury to the Achilles tendon by mitigating the extra stretch. FEET Plantarflexion With Tubing Execution 1. Sit on the floor with legs fully extended in front of the body. A length of surgical tubing, an end in each hand, should extend underneath the foot, wrapping around the ball of the foot where the metatarsal heads are located. The tubing needs to be taut, with no slack, before the exercise begins. 2. Extend (plantarflex) the foot to full extension. 3. At full extension, hold the position for one second before pulling the tubing backward in a smooth, continuous fashion. The foot will be forced to dorsiflex and return to its initial position. 4. Repeat the push and pull of the exercise, adjusting tension throughout, until fatigue. Muscles Involved Primary: tibialis posterior, flexor hallucis longus Soft Tissue Involved Primary: posterior talofibular ligament, calcaneofibular ligament Running Focus In chapter 4, a discussion of the adaptations required for running at different speeds and terrains offers some insight into the role of the feet and ankles in running performance. This exercise promotes strength and flexibility of the foot and ankle to prevent injury when running on uneven terrain and aids in the support phase of the gait cycle. Because this exercise is not weight bearing, it can be performed daily. It can function as a rehabilitative exercise to overcome an ankle sprain, or it can stand alone as a strengthening exercise to promote improved strength and flexibility. Because the exerciser controls the tension of the surgical tubing, the exercise can be made as difficult or as easy as possible for each repetition. The emphasis should be on a smooth but explosive movement with the appropriate resistance being provided by the tautness of the tubing, which can easily be adjusted by applying or lessening tension through gradually pulling or releasing the ends of the tubing held in each hand. FEET Dorsiflexion With Ankle Weights TECHNIQUE TIP ▶ The speed of the movement is not fast, but the muscles of the foot and the tendons of the ankle need to be dynamically engaged. Execution 1. Sit on a table with knees bent and lower legs dangling. An ankle weight providing appropriate resistance is secured around the midfoot. The upper body is erect with hands by the sides providing balance only. 2. In a smooth but forceful motion, the foot dorsiflexes (points upward and back) toward the tibia to full extension. The lower leg remains bent at 90 degrees and does not swing to aid the foot and ankle in moving the weight. 3. Gently lower (plantarflex) the foot (it does not need to be fully extended) and repeat the exercise to fatigue. Switch the ankle weight to the other foot and repeat the exercise. Muscles Involved Primary: tibialis anterior Soft Tissue Involved Primary: anterior talofibular ligament, calcaneofibular ligament, plantar tendon Running Focus This is another non-weight-bearing foot and ankle exercise that can be done daily both as an injury rehabilitation exercise as well as to improve strength and flexibility. The amount of weight of the ankle cuff can be varied to fine-tune the goal of the exercise. For example, a heavier weight performed fewer times with fewer sets emphasizes the strengthening of the anatomy affected. A lighter weight allows for more repetitions and sets, which aids the flexibility and endurance of the anatomy affected. VARIATION Dorsiflexion With Tubing This exercise can also be done with tubing, like the plantarflexion exercise. It can actually be done alternately by first plantarflexing the foot against the resistance of the tubing, and then immediately resisting when the tubing is pulled toward the body, until it is fully flexed and ready to plantarflex again. FEET Foot Eversion With Elastic Band Execution 1. Sit on a weight bench with the legs fully extended so that only the Achilles tendons, ankles, and feet are off the bench. Support the body by placing both hands on the bench behind the body. Wrap an elastic band tautly around both feet, which are plantarflexed, soles down, leaving approximately six inches of space between the feet. 2. Rotate the feet inward, dropping the big toes, and pushing outward with the feet against the resistance of the band. Hold for three to five seconds. 3. Relax the feet, rest for three to five seconds, and repeat. Muscles Involved Primary: peroneus longus, peroneus brevis, extensor digitorum longus Running Focus As mentioned in the introduction to this chapter, pronation happens as a result of movements on three planes, not just one. One of these movements is the eversion of the foot; during plantarflexion, eversion is controlled mainly by the peroneus longus, and in dorsiflexion, the peroneus brevis. This exercise is performed in the plantarflexed position because it is an easier movement, particularly for a runner who is an overpronator. Underpronators, also called supinators, benefit from this exercise because it is not the natural motion of their feet. FEET Foot Inversion on Bosu Ball Execution 1. Step onto a properly inflated Bosu ball with the dome side up. Establish foot position to ensure a properly balanced body. 2. While standing on the Bosu ball with feet in an inverted position, perform any standing exercise from the book (see the Running Focus section that follows for details). 3. Fatigue sets in quickly, so stepping onto a flat surface as a break between reps on the Bosu ball can be taken as needed. Muscles Involved Primary: tibialis posterior Secondary: extensor hallucis longus Running Focus Bosu balls are touted by fitness trainers as a tool for developing balance and proprioception. The development of balance and proprioception benefits the runner racing and training off-road, and the improved ankle strength and flexibility derived from the inverted position of each foot on the ball supports each foot through the gait cycle. The exercise performed is less important than the emphasis placed on maintaining balance on the Bosu ball. Given the curvature of the dome, the feet are in an inverted position on the ball throughout the exercise. For example, performing squats with dumbbells would be a good exercise to promote strengthening of the feet and ankles in the inverted position. Another less dynamic exercise would be to perform dumbbell curls. Or you could do one set or multiple sets of each. The emphasis is on the inverted position of the foot, but combining it with another exercise makes for a time-saving compound movement. The use of the Bosu ball also adds a twist to normal strength-training exercises like dumbbell curls and dumbbell squats, making for a more varied and enjoyable strength-training routine. However, some exercises should not be performed on the Bosu ball. Specifically, exercises that require placing a lot of weight and torque on the knee joints (e.g., full squats with heavy weight) should be avoided. CHAPTER 10 COMMON RUNNING INJURIES If this book had been written without thought for any downside to running, we would have done readers a great disservice. It would be naive in the extreme to imagine that it is possible to run and exercise in a more efficient manner without meeting some of the pitfalls that almost every runner encounters at some time. Some of these are beyond human control, but others are certainly preventable if thought is given to the long-term aim of the training program. If the exercises in this book are followed, the time allocated both to exercise and to running will increase. One handy rule is never to step up either the mileage or the time spent running by more