Electrical injuries


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Electrical injuries

  1. 1. Electrical injuriesAnastassios C. Koumbourlis, MD, MPH Electrical injury is a relatively infrequent but potentially dev- control system or due to paralysis of the respiratory muscles.astating form of multisystem injury with high morbidity and Presence of severe burns (common in high-voltage electricalmortality. Most electrical injuries in adults occur in the work- injury), myocardial necrosis, the level of central nervous systemplace, whereas children are exposed primarily at home. In nature, injury, and the secondary multiple system organ failure determineelectrical injury occurs due to lightning, which also carries the the subsequent morbidity and long-term prognosis. There is nohighest mortality. The severity of the injury depends on the specific therapy for electrical injury, and the management isintensity of the electrical current (determined by the voltage of symptomatic. Although advances in the intensive care unit, andthe source and the resistance of the victim), the pathway it especially in burn care, have improved the outcome, preventionfollows through the victim’s body, and the duration of the contact remains the best way to minimize the prevalence and severity ofwith the source of the current. Immediate death may occur either electrical injury. (Crit Care Med 2002; 30[Suppl.]:S424 –S430)from current-induced ventricular fibrillation or asystole or from KEY WORDS: high- and low-voltage electrical injury; lightening;respiratory arrest secondary to paralysis of the central respiratory multiple system organ failureA lthough electricity is a rela- (2). Electrocutions at home account for suites), where several procedures are per- tively recent invention, hu- 200 deaths per year, and they are formed utilizing high-voltage energy for mans have always been ex- mostly associated with malfunctioning or diagnostic and therapeutic purposes (e.g., posed to electrical injuries misuse of consumer products (3). Elec- defibrillators, pacemakers, electrosurgi-caused by lightning. The devastating trical injuries are also the cause of con- cal devices) (5– 8).power of lightning was viewed with awe, siderable morbidity. Electrical burns ac-and understandably, it was attributed to count for approximately 2–3% of all PRINCIPLES OF ELECTRICITYsupernatural powers. Zeus, the ruler of burns in children that require emergencythe ancient Greek gods, was characteris- Electricity is the flow of electrons (the room care ( 2000 cases per year). Thetically depicted holding thunderbolts, negatively charged outer particles of an vast majority of electrical burns in chil-which he used as warning or punishment atom) through a conductor. An object dren take place at home and are associ-against those who disobeyed him. The that collects electrons becomes nega- ated with electrical and extension cordsdiscovery and widespread use of electric- tively charged, and when the electrons (in about 60 –70% of the incidents) andity in the mid-1800s took away (to some flow away from this object through a con- with wall outlets, which account for an- ductor, they create an electric current,extent) the supernatural aura surround- other 10 –15% of the cases (3). Lightninging electrical power but, in return, made which is measured in amperes. The force is responsible for an average of 93 deaths that causes the electrons to flow is theelectrical injury a common problem at annually in the United States, whereaswork or at home, with the first electrical voltage, and it is measured in volts. Any- the morbidity is estimated to be 5 to 10 thing that impedes the flow of electronsfatality recorded in France in 1879 (1). times higher than that due to other forms Despite significant improvements in through a conductor creates resistance, of electrical injury. (4) which is measured in ohms (1). An elec-product safety, electrical injury is still the Because severe electrical injuries tendcause of many fatalities and of consider- trical injury will occur when a person to occur primarily in the workplace, they comes into contact with the current pro-able morbidity. Electrical injuries (ex- usually involve adults, and therefore, theycluding lightning) are responsible for duced by a source. This source can be a account for only a small percentage of the human-made one (e.g., the power line of 500 deaths per year in the United overall number of admissions to pediatric a utility company) or a natural one, suchStates. A little more than half of them intensive care units (ICUs). However, as a lightning.occur in the workplace and constitute the considering that both the home and work Electrical power is generated andfourth leading cause of work-related trau- environments are full of electrically pow- transmitted via a system of three conduc-matic death (5– 6% of all workers’ deaths) ered devices, the potential of accidental tors with the same voltage but with wave- injury is ever present, and it is necessary forms that reach their peak at a different for the intensivist to know the character- phase. This three-phase system allows for From the Division of Pediatric Critical Care, College istics and the principles of management a more efficient generation and transmis-of Physicians and Surgeons of Columbia University,Morgan Stanley Children’s Hospital of New York Pres- of this type of injury. Of particular im- sion of power. Power lines used by utilitybyterian, New York, NY. portance is the possibility of iatrogenic companies are classified according to Copyright © 2002 by Lippincott Williams & Wilkins electrical injury in the ICU (and in the their voltage from phase to phase, and DOI: 10.1097/01.CCM.0000035099.55766.EA operating room and electrophysiology they range from “low” (when they carryS424 Crit Care Med 2002 Vol. 30, No. 11 (Suppl.)
  2. 2. 600 V) to “ultrahigh” (with voltage of ductor in a cyclic fashion. This type of thundercloud and the ground overcomes 1 million volts). Utility power lines with current is the most commonly used in the insulating properties of the surround-high voltages tend to be located in households and offices, and it is standard- ing air. The current of a lightning strikesparsely populated areas, and therefore, ized to a frequency of 60 cycles/sec (60 rises to a peak in about 2 sec, and it laststhe possibility of an accidental contact Hz). When the current is direct, the elec- for only 1–2 msec. The voltage of a light-with them is relatively limited for the trons flow only in one direction (1, 10). ning strike is in excess of 1,000,000 V andgeneral population (9). This type of current is produced by vari- it can generate currents of 200,000 A. Through a succession of transformers, ous batteries and is used in certain med- Transformation of the electrical energy tothe voltage is gradually reduced, and the ical equipment such as defibrillators, heat can generate temperatures as highpower lines that distribute electricity for pacemakers, and electric scalpels. Al- as 50,000°F. However, the extremelyhomes, buildings, and the general indus- though AC is considered to be a far more short duration of lightning preventstry carry low voltage, defined by the Na- efficient way of generating and distribut- struck objects from melting (11, 12). Ta-tional Electrical Code as 600 V. Most ing electricity, it is also more dangerous ble 2 presents a comparison between thehomes and buildings in the United States than DC (approximately three times) be- major characteristics and effects of light-and Canada have a 120/240 V, single- cause it causes tetanic muscle contrac- ning vs. high- and low-voltage electricalphase system that provides the 240 V for tions that prolong the contact of the vic- currents.the high-power appliances and the 120 V tim with the source (10). This issue offor general use. The latter accounts for safety over efficiency became a dominant DETERMINANTS OFmost of the accidental injuries. The one in the early days of electricity when ELECTRICAL INJURYhousehold voltage in most other coun- Thomas Edison (who developed and pop-tries (Europe, Australia, Asia) is usually ularized DC) was fighting against George Electrical injury involves both directhigher (220 V) (9). Table 1 shows the Westinghouse (who developed AC). To il- and indirect mechanisms. The directdifferent physiologic effects of electrical lustrate the dangerous nature of AC, Edi- damage is caused by the actual effect thatcurrents generated by common house- son convinced the New York State legis- the electric current has on various bodyhold voltage. lature to use AC for the first death penalty tissues (e.g., the myocardium) or by the Electrical current exists in two forms, by electrocution (coined as “Westing- conversion of electrical to thermal energythe alternating current (AC) and the di- housed”). that is responsible for various types ofrect current (DC). In the former, the elec- Lightning is a form of DC that occurs burns. Indirect injuries tend to be pri-trons flow back and forth through a con- when the electrical difference between a marily the result of severe muscle con- tractions caused by electrical injury. In general, the type and extent of anTable 1. Pathophysiologic effects of different intensities of electrical current electrical injury depends on the intensity Current Intensity Probable Effect (amperage) of the electric current (1). According to Ohm’s law, the electric cur- 1 mA Tingling sensation; almost not perceptible rent is proportional to the voltage of the 16 mA Maximum current a person can grasp and “let go” source and inversely proportional to the 7–9 mA “Let-go” current for an average man resistance of the conductor: current 6–8 mA “Let-go” current for an average woman 3–5 mA “Let-go” current for an average child voltage/resistance (1). Thus, exposure of 16–20 mA Tetany of skeletal muscles different parts of the body to the same 20–50 mA Paralysis of respiratory muscles; respiratory arrest voltage will generate a different current 50–100 mA Threshold for ventricular fibrillation (and by extension, a different degree of 2A Asystole damage) because resistance varies signif- 15–30 A Common household circuit breakers 240 A Maximal intensity of household current (U.S.) icantly between various tissues (10). The least resistance is found in nerves, blood, Based on data obtained from References 1, 9, and 10. mucous membranes, and muscles; theTable 2. Comparison between lightning, high-voltage, and low-voltage electrical injuries Lightning High Voltage Low VoltageVoltage, V 30 106 1,000 600 ( 240)Current, A 200,000 1,000 240Duration Instantaneous Brief ProlongedType of current DC DC or AC Mostly ACCardiac arrest (cause) Asystole Ventricular fibrillation Ventricular fibrillationRespiratory arrest (cause) Direct CNS injury Indirect trauma or tetanic contractions of Tetanic contractions of respiratory muscles respiratory musclesMuscle contraction Single DC: single; AC: tetanic TetanicBurns Rare, superficial Common, deep Usually superficialRhabdomyolysis Uncommon Very common CommonBlunt injury (cause) Blast effect, shock wave Muscle contraction, fall Fall (uncommon)Mortality (acute) Very high Moderate Low DC, direct current; AC, alternating current; CNS, central nervous system.Crit Care Med 2002 Vol. 30, No. 11 (Suppl.) S425
  3. 3. highest resistance is found in bones, fat, resistor and not as a compendium of mul- ELECTRICAL INJURY TOand tendons. Skin has intermediate resis- tiple resistors (14). SPECIFIC TISSUES ANDtance (10). The duration of the contact with elec- ORGANS From a practical standpoint, one could trical current is an important determi-make a distinction between the external nant of injury. Thus, an electric shock Electrical injury should be viewed andresistance (represented by the skin) and caused by AC will produce greater injury managed as a multisystem injury, andthe internal resistance (which includes than a shock caused by DC of the same there is virtually no organ that is pro-all the other tissues) of the body. The skin amperage because the DC causes a single tected against it. Although multisystemis the primary resistor against the elec- muscle contraction that “throws” the vic- injuries can be very extensive, it is dam-trical current, with a resistance ranging tim away from the power source, thus age to the vital organs that may requirein adults between 40,000 and 100,000 , minimizing the injury (10). These differ- intensive care and accounts for the fatal-depending on its thickness (i.e., the ences have practical significance only at ities. The most important potential inju-thicker the skin, the higher its resis- low voltages, whereas in high voltages, ries are as follows:tance). Thus, the intensity of the electri- both currents have a similar effect.cal shock produced by a certain voltage The pathway of the current through Cardiovascular Systemwill vary between victims of different sex the body (from the entry to the exit point)and age. For example, exposure to the determines the number of organs that are Pathophysiology. Electrical injurycommon household voltage (120 V) of an affected and, as a result, the type and may affect the heart in two ways: by caus-adult laborer with thick, calloused palms severity of the injury. The determination ing direct necrosis of the myocardiumwhose resistance may be in excess of of the electrical pathway is important and by causing cardiac dysrhythmias. To100,000 will create a current of approx- both for acute management and for over- some extent, the degree of the myocardialimately 1 mA, which is barely perceptible. all prognosis. A vertical pathway parallel injury depends on the voltage and theIn contrast, the same exposure on a new- to the axis of the body is the most dan- type of current, being more extensiveborn infant whose skin is very thin and gerous because it involves virtually all the with higher voltage, and for any givenhas a high water content (which mark- vital organs (central nervous system, voltage, it is more severe with AC thanedly lowers its resistance) will probably heart, respiratory muscles, and in preg- with DC. The injury may be focal or dif- nant women, the uterus and the fetus). A fuse and usually consists of widespread,cause significant injury. Even more im- horizontal pathway from hand to hand discrete, patchy contraction band necro-portant than the thickness is the mois- will spare the brain but can still be fatal sis involving the myocardium, nodal tis-ture of the skin (1, 10, 13). Presence of due to involvement of the heart, respira- sue, conduction pathways, and the coro-simple sweat may decrease the resistance tory muscles, or spinal cord. A pathway nary arteries (16 –19).of the skin to 1000 . Wet skin (e.g., through the lower part of the body may Rhythm disturbances may be pro-electrocution of a person in a bathtub or cause severe local damage but will prob- duced with exposure to relatively low cur-in a swimming pool) offers almost no ably not be lethal (15). rents. A current of more than 50 –100 mAresistance at all, thus generating the Whereas electric shock from a low- (which is less than half of the maximalmaximal intensity of current that the voltage line is delivered on contact of the current that can be generated after expo-voltage can generate. Moist mucus mem- victim with the source, in high-voltage sure to regular household current) withbranes also have negligible resistance, injury, the current is carried from the hand-to-hand or hand-to-foot transmis-thus maximizing any current with which source to the person through an arc be- sion can cause ventricular fibrillation.they come into contact. This causes sig- fore any actual physical contact is made. Exposure to high-voltage current (AC ornificant orofacial injury to infants and The arc may form into or over the body of DC) will most likely cause ventriculartoddlers who tend to put live wires in a person. Arcs can generate extremely asystole. Lightning acts as a massive cos-their mouths. high temperatures (up to 5000°C) that mic countershock that causes cardiac The internal resistance of the body are usually responsible for the severe standstill. Interestingly, because of thecomprises all the other tissues and is thermal injuries from high voltage (9). inherent automaticity of the heart, sinusestimated to be between 500 and 1000 . Lightning current strikes the victim in an rhythm may spontaneously return (20).Although bones, tendons, and fat offer altogether different way than low or high A variety of other (usually transient)the most resistance to electric current, voltage. At least four primary modes of cardiac dysrhythmias have been reportedthey are not likely to be contact points. lightning injury have been described: di- in survivors of electrical injuries, andWhen exposed to electric current, they rect strike, in which the major pathway of their pathogenesis is rather unclear andtend to heat up and coagulate before con- lightning current is through the victim; most likely multifactorial. Possible mech-ducting the current (10). Nerves and side flash, in which a direct strike to an anisms include arrhythmogenic foci dueblood vessels, on the other hand, are the object (or a person) is followed by a sec- to myocardial necrosis, alterations in thebest conductors: the former because they ondary discharge from the object to a Na -K –adenosine triphosphatase con-are designed to carry electrical currents nearby victim; stride potential, in which centration, and changes in the perme-and the latter due to their high water the lighting hits the ground and then ability of myocyte membranes. Finally,content. It has been suggested that these enters the victim’s body from one foot cardiac injury and rhythm disturbancesproperties create the path of least resis- and exits from the other foot; and flash- can be caused by anoxic injury in cases intance for current after it enters the body, over phenomenon, when the energy flows which respiratory arrest precedes the in-thus affecting primarily the nerves and outside the body, often causing vaporiza- jury to the heart. Although delayed dys-blood vessels. In reality, it seems that tion of surface water with a blast effect to rhythmias are possible, they tend to oc-internal tissues of the body act as a single clothing and shoes (9 –11). cur only in patients who had some otherS426 Crit Care Med 2002 Vol. 30, No. 11 (Suppl.)
  4. 4. form of dysrhythmia on presentation. 75 mA/mm2, which is well within the of the current through the lips causes theLate dysrhythmias are probably due to range capable of causing ventricular fi- burn. The burn may be full thickness,arrhythmogenic foci secondary to patchy brillation (Table1). In other words, a pa- involving the mucosa, submucosa, mus-myocardial necrosis and especially due to tient may die before there is time to cause cle, nerves, and blood vessels. Significantinjury of the SA node (16 –21). significant surface burns (9, 13, 23). In edema and eschar formation follow Electrical injury may cause direct and addition, because the resistance of the within hours after the injury. The escharindirect effects on the vascular bed, skin may be markedly altered by mois- usually falls off after 2–3 wks, being re-which due to its high water content, is an ture, electric current may be transmitted placed by granulation tissue and scarringexcellent conductor. The effects of the to deeper tissues before it causes signifi- that may cause considerable deformity.electric current vary among different size cant damage to the skin. Electric current Injury to the labial artery may cause sig-vessels. Large arteries are not acutely af- may be retained by resistant bony struc- nificant bleeding. However, because thefected because their rapid flow allows tures, and the heat may cause massive eschar is usually covering the artery,them to dissipate the heat produced by coagulation and necrosis of deep muscles bleeding may not present until the escharthe electric current. However, they are and other tissues, almost completely falls off days after the initial injury (10,susceptible to medial necrosis, with an- sparing the skin. Thus, in contrast with 28).eurysm formation and rupture. Smaller burns caused by fires, the severity of the Clinical Manifestations. Clinical man-vessels are acutely affected due to coagu- skin burns cannot be used to assess the ifestations of burns will depend on theirlation necrosis and tend to be affected degree of internal injury in an electrical extent and severity. When extensive flashprimarily as a result of a high-voltage accident with low voltage (15, 23–25). and flame burns are present the patient isinjury (but only rarely with lightning). More serious burns are usually caused expected to develop severe hemodynamic,Vascular injury in the extremities is very by exposure to arcs that are created in autonomic, cardiopulmonary, renal, met-likely to cause compartment syndrome accidents with high-voltage currents abolic, and neuroendocrine responsesthat further compromises the circulation ( 1000 V). In such cases, the severity of that accompany more common thermal(10, 22). the burn depends not only on the tem- burns and that are described in detail in Clinical Manifestations. Cardiac perature but also on the energy within another section of this journal. Burnsstandstill and ventricular fibrillation are the arc. Exposure to an arc may rapidly caused by lightning rarely require specialobviously the most serious of the cardiac break down the epidermis of the skin (as care.complications of electric injury and are fast as 1 msec), thus decreasing the bodyinvariably fatal unless immediate resusci- resistance to that of the internal organs Nervous Systemtative efforts are undertaken. However, (500 –1000 ). The combination of highthere are also several other dysrhythmias temperature and high current in an arc Pathophysiology. Although nervousthat have a much better prognosis. causes a variety of burns including: “flush system injury (involving the central andAmong the most common are sinus burns,” which are thermal burns due to the peripheral nervous system) is a com-tachycardia and nonspecific ST- and T- the heat generated by the arc; “electro- mon clinical manifestation of electricalwave changes. Conduction defects, such thermal burns,” due to the passage of the injury, there is no specific histologic oras various degrees of heart blocks, bun- electric current through the body; and clinical finding that is considered patho-dle-brunch blocks, and prolongation of “flame burns,” usually from ignition of gnomonic. Furthermore, in many in-the QT interval, are also common. Fi- clothing. Burns due to lightning are stances, nervous system injury is not duenally, supraventricular tachycardias and common (up to 89% in one series), but to the direct effect of the electrical cur-atrial fibrillation have been reported. In despite the massive energy and heat that rent itself but due to trauma or dysfunc-the majority of cases, these dysrhythmias lightning generates, its short duration tion of other organ systems (usually car-do not cause significant hemodynamic and flash-over effect play a protective diorespiratory).compromise. On echocardiogram, there role. As a result, deep burns occur in only Among the acute direct effects of pas-may be some depression of the right and 5% of victims (26). When they occur, sage of electrical current through theleft ejection fractions (16 –20). burns may be of different types, including brain, the most serious is injury to the partial-thickness linear (mostly in areas respiratory control center that results re-Cutaneous Injuries and Burns of high sweat concentration), punctate spiratory arrest. Acute cranial nerve def- (groups of small, deep, circular burns), icits and seizures may also occur after Pathophysiology. Exposure to cur- thermal (usually from ignition of clothes electric injury to the brain. Direct injuryrents generated by low-voltage sources or contact with metal objects), and feath- to the spinal cord with transection at the(including household electric sources) ering burns. The latter (also called Lich- C4 –C8 level may occur with a hand-to-may cause a variety of cutaneous injuries tenburg figures, ferns, or keraunographic hand flow. Even relatively low-intensityfrom the transformation of electrical to markings) are cutaneous marks that are current (30 mA) at the frequency ofthermal energy. The injuries can range considered pathognomonic of lightning, household current (60 Hz) may induce anfrom local erythema to full-thickness but it is unclear whether they are actual indefinite refractory state at the neuro-burns. The severity of the burn depends burns (27). muscular junction, causing continuouson the intensity of the current, the sur- Special mention should be made of tetanic contractions of involved muscles.face area, and the duration of exposure. oral electrical burns in children and These tetanic contractions are responsi-First-degree electrical burns require an burns caused by lightning. The most ble for the “locking-on” phenomenonexposure of at least 20 secs to a current of common mode of electrical shock in that prevents the victim’s hand from sep- 20 mA/mm2, whereas a second or third young children is from chewing or biting arating from the electrical source and fordegree burn requires exposure to at least on electrical cords. In such cases, arcing suffocation that is caused by contractionCrit Care Med 2002 Vol. 30, No. 11 (Suppl.) S427
  5. 5. of respiratory muscles. Among the most high-voltage current that knocks the vic- pulmonary resuscitation and acute mul-common indirect injuries causing signif- tim to the ground. tiple trauma care. Treatment generallyicant central nervous system injury are Clinical Manifestations. In addition to follows the same principles of pediatricbrain ischemia or anoxia secondary to apnea in cases of respiratory arrest, pa- and adult resuscitation as any other trau-antecedent cardiorespiratory arrest and tients may exhibit a variety of nonspecific matic injury. The type of care that thetraumatic brain or spinal cord injury sec- respiratory patterns that reflect distur- victim of an electrical injury requires var-ondary to a fall. Peripheral nerves may bances of other organ systems (e.g., hy- ies according to the type and severity ofincur secondary damage due to local perpnea or hypopnea due to central ner- the initial injury. However, certain con-burns or entrapment from scar forma- vous system dysfunction, fluid shifts, ditions need to be evaluated, monitored,tion, vascular injury, or edema. Upper- cardiac dysfunction, and pain) rather and treated in almost all cases. Specifi-motor neuro-deficits are relatively com- than from specific injury to the respira- cally for patients admitted to the ICU, themon, affecting primarily the lower limbs tory system. Of course, as is the case with following issues should be considered:(10, 15, 29 –33). almost every other critical illness, sur- vivors of electrical injury may develop ● Thorough evaluation for hidden injury Clinical Manifestations. Loss of con- respiratory complications as a result of (especially spinal cord injury) and forsciousness, confusion, and impaired re- their injury or treatment (e.g., acute blunt thoracic or abdominal trauma.call tend to be very common among vic- respiratory dysfunction syndrome sec- ● Serial evaluation of liver, pancreatic,tims of electrical injury. If there is no ondary to ischemia or aggressive fluid and renal function for traumatic andother associated injury, they tend to re- resuscitation, ventilator-associated anoxic/ischemic injury (in case of car-cover well. Dysfunction of peripheral mo- pneumonia) (10). diorespiratory arrest), supplementedtor and sensory nerves acutely causes a by appropriate imaging studies (e.g.,variety of motor and sensory deficits. Sei- computed tomography or abdominalzures, visual disturbances, and deafness Other Systems sonogram) as necessary.may be present. In more severe cases Among other organ systems that may ● CT scan of the head is indicated in allinvolving brain hemorrhage or other incur significant damage due to electrical severe cases of lightning injury, of in-traumatic or ischemic/anoxic injury, the injury, the kidneys are of particular im- juries due to a fall, and if there arepatient may become comatose. Hemiple- portance. Although direct injury from persistent abnormal findings in thegia or quadriplegia are common with sig- electric current is unusual, the kidneys neurologic examination.nificant spinal cord injury. Transient pa- are very susceptible to anoxic/ischemic ● Preventive treatment for stress ulcers.ralysis (keraunoparalysis) and autonomic injury that accompanies severe electrical ● Psychiatric assessment and support asinstability causing hypertension and pe- injury. In addition, vascular compromise soon as the patient is conscious andripheral vasospasm have been described and muscle necrosis may cause renal tu- hemodynamically stable.primarily in the context of electrical in- bular damage, leading to renal failurejury due to lightning, and they are be- from release of myoglobin and creatinine Patients with high-voltage injury alsolieved to result from massive release of phosphokinase. require the following:catecholamines (10, 15, 29 –33). The skeletal system may have frac- tures either from severe muscle contrac- ● Evaluation for rhabdomyolysis and tions or from injury due to falls from myoglobinuria (uncommon in light-Respiratory System significant heights. Fractures are more ning injury). common in upper limb long bones and in ● Evaluation of the limbs for compart- Pathophysiology. Although respira- ment syndrome that may require fas-tory arrest is one of the common causes vertebrae. The latter may cause spinal cord injuries, further complicating the ciotomy (rare in lightning injury).of acute death in serious electrical inju- ● Nutritional support due to increasedries, there are no specific injuries to the problem. The eyes and the ears may be entry energy expenditures.lungs or the airways directly attributable ● Ophthalmologic and otoscopic evalua-to electric current. Respiratory arrest is points for a lightning strike and present a number of problems. Transient auto- tion (common in cases of lightning in-usually the result either of direct injury jury).to the respiratory control center, causing nomic disturbances may cause fixed pu-cessation of respiration, or to suffocation pils after a lightning injury that in asso- ciation with an often unconscious SPECIAL CONSIDERATIONSsecondary to tetanic contractions of therespiratory muscles, which occurs when patient, may be perceived as severe brain In contrast with other traumatic inju-the thorax is an involved pathway for the injury or even death. Up to 50% of pa- ries, electrical injuries present someelectric current. It is speculated that in a tients may experience rupture of the tym- rather unique problems that require spe- panic membranes and temporary senso-number of fatalities it is actually the an- cial consideration. rineural hearing loss. Cataracts are a veryoxic injury rather than the electric cur- Access to the Victim. In contrast with common complication of lightning injuryrent that causes irreversible injury to the other types of trauma, electrical injury but are rarely acutely present, especiallybrain and the heart. Thermal burns of the poses the same threat to the rescuer as it after lightning injury (10, 12, 15).airways or inhalation of toxic fumes and does to the victim because, if the victim ishot debris may occur, especially in cases still in contact with the source of the MANAGEMENT OF ELECTRICALof industrial accidents. Blunt trauma to current (as commonly happens with AC), INJURIESthe chest with pulmonary contusion and he or she becomes a conductor that mayassociated respiratory dysfunction is also The management of severe electrical electrocute the rescuer. Similarly, inpossible, especially with exposure to a injuries requires a combination of cardio- cases of injury with high voltage, theS428 Crit Care Med 2002 Vol. 30, No. 11 (Suppl.)
  6. 6. ground (especially if it is wet) may con- current to travel freely and damage inter- lems after electrical injury have been re-duct current to the rescuers. Thus, no nal organs without leaving significant ported, evidence from several studiesattempt to provide medical care should surface marks. Thus, although the pres- suggests that the most severe cardiacbe made until either the source of the ence of burns on the chest should raise complications present acutely, and it iselectrical current has been cut off or the the possibility of internal injuries, their very unlikely for a patient to develop avictim has been extricated safely away absence does not preclude them. Simi- serious or life-threatening dysrhythmiafrom the current source with the use of larly, skeletal injuries (including verte- hours or days later. Therefore, patientsproperly insulated equipment. In con- bral injury) may occur as a result of even who are asymptomatic and have a normaltrast to popular belief, contact with a a single severe muscle contraction, which ECG at admission to the emergency de-lightning victim does not pose any threat can dislocate or fracture bones without partment do not need cardiac monitoringto the rescuer; therefore, treatment may any sign of external traumatic injury. (34, 35). It is not clear whether this rec-be started immediately. Therefore, any victim of a severe electri- ommendation should apply to patients Triage. It is not unusual for electrical cal accident should be assumed to have a with a history of heart disease before theinjuries (especially lightning injuries) to spinal cord injury and should be managed injury. In one retrospective study ofcause multiple casualties (11, 12). In gen- with the proper head and neck immobi- adults who died due to electrical injury, aeral, in cases of several injured people, lization that is required for all victims history of coronary heart disease was notpatients believed to be already dead are with suspected or known spinal injury. found to be a risk factor between thosegiven the least priority, and efforts are Fluid Management. The combination who died acutely from an arrhythmia andfocusing on those who have signs of life. of extensive burns and significant inter- those who died later from other causesLightning victims are an exception to this nal visceral injury in cases of severe high- (36). In another study, the same authorsrule because patients struck by lightning voltage electrical injury leads to in- reported that none of the patients whomay become acutely apneic due to paral- creased fluid requirements due to fluid were discharged from their hospital afterysis of the central respiratory control, extravasation into third space compart- electrical injury had late adverse effects,may have dilated nonreactive pupils due ments and to ongoing fluid losses. In especially arrhythmias. But they never-to autonomic dysfunction, and may be addition, the massive muscle destruction theless recommended an ECG and 24-hrpulseless due to the cardiac standstill that accompanies these injuries may cardiac monitoring for children with his-caused by the mega-countershock of the cause significant myoglobinuria, which, tory of heart disease (37). Until more datalightning strike. Because of its inherent if significant, may lead to renal failure become available on the actual risk thatautomaticity, it is possible for the heart (10, 15). Thus, it is important to establish preexisting heart disease poses for theto recover spontaneously. Considering good intravenous access as soon as pos- patient with electrical injury, it seemsthat the majority of lightning victims sible and provide adequate fluids to main- reasonable to monitor such patients fortend to be relatively young and previously tain a normal urine output. If the patient 24 hrs after the injury. Considering thathealthy individuals, the possibility of suc- presents with signs of hypovolemic the numbers of potential victims who fitcessful resuscitation is high if proper care shock, immediate fluid resuscitation is this category is very small, such recom-is instituted immediately. Therefore, ad- indicated. Otherwise, the overall fluid mendation will not pose any unreason-ministration of oxygen and ventilation management should be judicious in con- able burden to ICUs or the cost of healthwith bag and mask should be started im- sideration of other problems that may care. On the basis of studies in adults andmediately on an apneic victim, and an already be present or develop (e.g., syn- children, the criteria for cardiac monitor-artificial airway should be established as drome of inappropriate antidiuretic hor- ing after an electrical injury are the fol-soon as possible to minimize the effects mone in case of traumatic or anoxic brain lowing: exposure to high voltage, loss ofof anoxia, a major cause of mortality. The injury and acute respiratory dysfunction consciousness, abnormal ECG at admis-potential for successful resuscitation has syndrome) and require fluid restriction. sion to the emergency department, andled people to believe that lightning causes Patient Monitoring. For most pa- past medical history of cardiac diseasea state of “suspended animation” from tients, disposition becomes clear after (especially a history of cardiac arrhyth-which the victim can recover virtually their initial evaluation in the emergency mia).unharmed. Unfortunately, this claim is department. Victims of a low-voltage The type of recommended cardiacnot substantiated. If the patient remains electrical injury or of a lightning injury monitoring is also controversial. Tradi-apneic, anoxia will lead to further brain who do not have cardiac arrest, have no tionally, cardiac monitoring refers toand cardiac damage refractory to treat- loss of consciousness and no burns, and continuous telemetry, serial ECGs, andment. whose neurologic examination and elec- serial measurement of cardiac enzymes. Severity of the Injury. Because the trocardiogram (ECG) are normal can be Although there is a consensus for the useactual severity of the electrical injury de- safely discharged home (34 –36). Patients of the telemetry and ECG, the prognosticpends on the pathway of the electric cur- who experienced cardiopulmonary arrest, value of the monitoring of cardiac en-rent, it is important to determine how have abnormal neurologic findings sug- zymes (myocardial muscle creatine ki-the injury occurred. If the patient was gesting central nervous system or spinal nase isoenzyme, CK-MB) and the use ofexposed to DC, there may be visible burns cord injury, or have severe burns and noninvasive and invasive imaging studiesat the entry and exit sites. In contrast, extensive visceral or vascular injury will (echocardiography, thallium studies, andbecause of its cyclic movement, AC may obviously require admission to the ICU or angiography) has been rather poor andnot cause discernible entry and exit to a specialized burn unit. inconsistent. The CK-MB fraction as anpoints. Another problem is that severe What has been less well defined is the index of myocardial injury may be mark-injury may occur when the skin is wet need for cardiac monitoring after electri- edly elevated entirely due to skeletal mus-and its resistance is low, thus allowing cal injury. Although late cardiac prob- cle and not myocardial injury. It has beenCrit Care Med 2002 Vol. 30, No. 11 (Suppl.) S429
  7. 7. reported that muscle injured by an elec- veillance and Investigative Findings. Wash- possibility of living again. Ann Intern Medtrical current can contain up to 25% ington, DC, Department of Health and Hu- 1968; 68:1345–1353CK-MB fraction (as opposed to the nor- man Services (NIOSH), May 1998, pp 9 –19. 21. Chandra NC, Siu CO, Munster AM: Clinical Publication No. 98-131 predictors of myocardial damage after highmal 2–3%) (38). There is no information 3. Hiser S: Electrocutions Associated with Con- voltage electrical injury. Crit Care Med 1990;regarding the changes in troponin levels sumer Products: Report. Washington, DC: 18:293–297after electrical injury. US Consumer Product Safety Commission, 22. Hunt JL, McManus WF, Haney WP, et al: Electrical Injury in the Pregnant Pa- Division of Hazard Analysis, Directorate for Vascular lesions in acute electric injuries.tient. 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