Children who have sustained minor household electrical injuries and are asymptomatic usually not require laboratory evaluation, cardiac evaluation, or hospitalization In more severe injuries, entry and exit wounds and arc burns are poor predictors of internal damage Tissue that appears viable initially may become ischemic over several days Current Evidence An electrical injury occurs when a person comes into contact with the current produced by a human-made or natural source The spectrum of electrical injury is enormous, ranging from low-voltage household accidents to million-volt lightning strikes ( Table 90.8 ) Appropriate management requires an understanding of the basic physical aspects of electricity, the physiologic responses to injury, and the potential for immediate and delayed damage Lightning that strikes individuals carries a 30% risk of mortality and claims approximately 100 lives annually in the United States The death rate is highest among children ranging from 15 to 19 years of age The majority of struck-bylightning injuries in the United States originate in the South and the Midwest Harnessed electrical power is responsible for approximately 700 deaths/year, of which 10% are children Household electrical cords are the major cause of electrocution in children 12 years of age and younger, with an estimated 1,000 ED visits for oral electrical burns from 1997 to 2012 High-tension electrical injuries dominate in older children who climb on trees, buildings, or utility structures Tasers and stun guns, which are high-voltage, low-current stimulators, cause pain due to involuntary muscle contractions The severity of electrical injury depends on six factors: (i) The resistance of skin, mucosa, and internal structures; (ii) the type of current (alternating or direct); (iii) the frequency of the current; (iv) the intensity; (v) the duration of contact; and (vi) the pathway taken by the current Precise separation of the effect of these factors, which are interrelated, is impossible Together, they produce either heat or current, and a variety of injuries result TABLE 90.8 LIGHTNING VERSUS HIGH-VOLTAGE ELECTRICAL INJURY Factor Lightning High voltage Duration Energy level Prolonged Much lower Type of current Shock wave Cardiac arrhythmia Burns Brief 100,000,000 V 200,000 A Direct Present Asystole Superficial, minor Renal failures Rare Fasciotomy and amputation Rare Usually alternating Absent Ventricular fibrillation Deep, frequently obscured Common secondary to myoglobinuria Common, early, extensive Resistance is a major factor determining the amount of current flow through tissue The intensity of the electrical shock produced by a certain voltage can vary with gender and age Tissue injury is inversely related to resistance Dry skin provides resistance of approximately 40,000 ohms, whereas thick, callused palms may provide up to × 106 ohms Thin, moist, or soiled skin lowers resistance to the 300 to 1,000 ohm range The highly vascular, moist oral mucosa has even lower resistance The type of current is another important determinant of injury Alternating current (AC) at low voltage is able to induce tetanic muscle contraction and is, therefore, more dangerous than direct current (DC) Normal household 60-Hz current changes direction 120 times per second, a frequency that induces an indefinite refractory state at neuromuscular junctions The resultant muscle contractions prevent the victim from releasing his grip (“locking-on”), thus extending the duration of contact DC is used in medical settings for cardiac defibrillation, countershock, and pacing Currents as low as mA may trigger ventricular fibrillation, and high currents may damage the heart and conducting tissues directly Lightning is another example of DC, discharged in a single, massive bolt that lasts 1/10,000 to 1/1,000 second The brevity of exposure makes deep thermal injury unlikely In general, high-voltage injury is more dangerous than low-voltage injury A higher voltage is more likely to cause “locking-on” and associated deep tissue injury, although its tendency to throw victims from the source of current may mitigate this effect The possibility of head and cervical spine injuries must be considered in these cases The value of the current, or amperage, is of even greater importance than the voltage Flow as low as to 10 mA may be perceived as a tingling sensation Progressively higher flows may paralyze muscles and ventilation, precipitate ventricular fibrillation, and cause deep tissue burns Clinical Recognition Electrical injury may produce a variety of clinical sequelae, ranging from local damage to widespread multisystem disturbances Victims of the most severe accidents are commonly pulseless, apneic, and unresponsive Current that passes directly through the heart may induce necrosis and ventricular fibrillation Brainstem (medullary) paralysis or tetanic contractions of thoracic muscles may result in cardiopulmonary collapse Lightning injury is capable of inducing asystole, from which the heart may recover spontaneously, but the accompanying respiratory failure is commonly prolonged Unless ventilation is initiated promptly, hypoxia leads to secondary ventricular fibrillation and death Other cardiac disorders, including arrhythmias and conduction defects, are common among survivors Supraventricular tachycardia, atrial and ventricular extrasystoles, right bundle branch block, complete heart block, and prolongation of the QT interval are most common Complaints of crushing or stabbing precordial pain may accompany nonspecific ST–T wave changes Some patients sustain myocardial damage or even ventricular wall perforation Despite evidence of important cardiac injuries, patients without secondary hypoxic–ischemic injury usually regain good myocardial function Nervous system injury is also common and may involve the brain, spinal cord, peripheral motor and sensory nerves, and sympathetic fibers Loss of consciousness, seizures, amnesia, disorientation, deafness, visual disturbances, sensory deficits, hemiplegia, and quadriparesis occur acutely but may be transient Vascular damage may produce subdural, epidural, or intraventricular hemorrhage, and patients with brain hemorrhage or ischemic injury may become comatose Additional problems develop within hours to days after injury The syndrome of inappropriate antidiuretic hormone secretion may precipitate cerebral edema Electroencephalograms reveal diffuse slowing, epileptiform discharges, or burst suppression patterns, but these may not have prognostic significance Spinal cord dysfunction more often results in motor than sensory deficit Peripheral neuropathies with patchy distribution may reflect direct thermal injury, vascular compromise, or current flow itself A variety of autonomic disturbances may resolve spontaneously or persist as reflex sympathetic dystrophy Transient paralysis (keraunoparalysis) has been described in electrical injury due to lightning possibly secondary to massive release of catecholamines Ocular damage is common, particularly after lightning strikes Direct thermal or electrical injury, intensive light, and confusion contribute to the presentation Findings include corneal lesions, hyphema, uveitis, iridocyclitis, and vitreous hemorrhage Choroidal rupture, retinal detachment, and chorioretinitis occur less often Autonomic disturbances in a lightning victim may cause fixed dilated pupils, which should not serve as a criterion for brain death without extensive investigation of other neurologic and ocular functions Cataracts and optic atrophy are possible late developments Electrical injury may induce direct or indirect complications in other organ systems Tetanic contractions may cause joint dislocations and fractures, especially of the upper extremity long bones and vertebrae Fractures of the skull and long bones may occur when high-tension shock throws the victim from the site of contact Early cardiopulmonary insufficiency, as well as direct renal effects, may cripple renal function Damaged muscle releases myoglobin and CPK As in crush injuries, myoglobin may induce renal tubular damage and kidney failure Pleural damage may cause large effusions, whereas primary lung injury or aspiration of gastric contents may lead to pneumonitis Gastric dilation, ileus, diffuse GI hemorrhage, and visceral perforation may occur immediately or later In addition to burns at the site of primary contact, burns are common where current has jumped across flexed joints Such burns are most common on the volar surface of the forearm and across the elbow and axilla Arcing current may also ignite clothing and produce thermal burns Entry and exit wounds and arc burns are poor predictors of internal damage Tissue that appears viable initially may become edematous and then ischemic or frankly gangrenous over several days Diminished peripheral pulses may provide immediate evidence of vascular damage, but strong pulses not guarantee vascular integrity Blood flow falls to a minimum at about 36 hours, but current or thermal damage may lead to vasospasm, delayed thrombosis, ischemic necrosis, or aneurysm formation and hemorrhage weeks after the injury Viable major arteries near occluded nutrient arteries may account for apparently adequate circulation and uneven destruction of surrounding tissues