Definition and Epidemiology

Injuries from an electrical accident can be minor or can involve severe damage, electrocution, and even death from an electrical fire or cardiopulmonary arrest.¹ In the United States, there are approximately 400 deaths and 4000 electrical injuries yearly, with an additional 140,000 electricity-related fires accounting for an additional 400 deaths and 4000 injuries.² Each year, 1000 people are killed in electrical accidents. Although the actual number of accidental and environmental electrical injuries is uncertain, electrical injuries are the fourth leading cause of death in the workplace, the result of electricity-related trauma, burns, or shock.³ In addition to the aforementioned injuries, electrical injuries can also cause cardiac arrhythmias and respiratory arrest as well as seizures.⁴

Electrical injuries caused by low-voltage current account for 60% to 70% of reported electrical injury and have been responsible for nearly half of deaths from electrical shock and 1% of accidental deaths in the home.⁵ This number is declining, likely because of the widespread use of grounded plugs. The majority of household electrocutions involve 110- or 220-V current and are usually the result of failure to ground tools or appliances or the use of hair dryers or other electrical devices near water. Contact with low- and high-voltage electrical current is responsible for a significant number of hand and oral injuries in children.⁵ The most common cause of electrical injury in children younger than 6 years is oral contact with electrical cords or wall sockets and the placement of conductive bodies in wall sockets. Adolescent boys 11 to 18 years of age often sustain high-voltage injuries in tree- or pole-climbing accidents.

Lightning is a common but rarely fatal natural phenomenon. In recent years, fatalities related to lightning strikes have decreased to fewer than 50 each year.⁶ Seventy to 90% of people struck by lightning survive but will have permanent sequelae.⁷

Immediate emergency department referral or physician consultation is indicated for patients with electrical injuries.

Pathophysiology

Electrical injuries result from the direct effects of current and from the conversion of electrical energy into thermal energy as current passes through body tissues. Factors that determine the severity and distribution of injury include the type of current, voltage, amperage, tissue resistance, surface contacted, pathway of current, duration of contact, and other associated trauma.⁸ Alternating current (AC), the more common cause of electrical injuries, is more dangerous than direct current (DC) because it can produce tetanic skeletal muscle contractions and prevent the victim from letting go of the energized source, thus increasing current delivery to the victim. AC voltage at 25 to 300 Hz and 25 to 220 V, the common household current level, can easily cause ventricular fibrillation if the pathway of the current includes the heart. Low-voltage contact, although potentially lethal, does not result in the magnitude of tissue necrosis seen with high-voltage injury. The voltage in a lightning strike is in the range of 10 million to 2 billion volts, but the duration of a lightning strike is short.

Heat generation is responsible for most burns seen with electrical injuries. Heat damage is proportional to tissue resistance. Tissues with high fluid and electrolyte content conduct electrical current better than others do. Listed in decreasing order of magnitude of tissue necrosis are nerves, blood vessels, muscle, skin, tendon, fat, and bone. Nerve tissue has the least resistance to direct flow and therefore is most easily damaged.⁸ Electrical current passing through the head or crossing the thorax is more likely to cause respiratory arrest or ventricular fibrillation than is current passing through the leg. Skin, the initial barrier to current flow, is an effective insulator to deeper tissues. As current flows from the contact point, tissue with the least electrical resistance sustains the greatest current density and destructive injury. The most severe cutaneous and deep injuries are adjacent to contact sites, and the damage decreases with increasing distance from damage points.

Clinical Presentation

The spectrum of electrical injury ranges from a transient unpleasant sensation to instantaneous death. Injuries from electricity occur by three mechanisms: (1) the direct effect of current on tissue; (2) the conversion of electrical energy to heat, causing burns; and (3) a mechanical injury caused by muscle contraction, falling, or a direct lightning strike. Cardiopulmonary arrest is the primary cause of immediate fatalities from electrical injury and is common in patients with high-voltage electrical and lightning injury. In lightning injuries, cardiac activity can spontaneously return, but the associated respiratory arrest often continues, causing death.⁹ Common sequelae include hypertension; tachycardia; cardiac muscle necrosis; respiratory paralysis; burns; fractures; ruptured tympanic membrane; hyphema; vitreous hemorrhage; and injuries to the spinal cord, peripheral nervous system, and vascular systems.¹⁰ Oliguria or anuria from deep tissue damage and rhabdomyolysis can cause acute renal failure. Visible myoglobinuria indicates massive acute muscle necrosis and impending renal failure. Disseminated intravascular coagulation can result from massive trauma. Neurologic deficits are sometimes evident immediately after the current exposure. However, complications such as reflex sympathetic dystrophy and motor neuron disease may not become apparent for days to months after the electrical trauma.¹¹ Long bone fracture often occurs with falls, and fractures (particularly of the vertebral column) can result from tetanic muscle contraction at the time of electrocution.¹¹ Cataracts can form up to 2 years after such injury.¹¹ Direct injury to internal organs is uncommon.

Physical Examination

When evaluating a victim with an electrical injury, the health care provider should always completely undress the patient to determine entry and exit wounds and associated injuries. Patients should be assessed for associated cranial, spinal, or other trauma, and the neck should initially be treated as being unstable, particularly with DC injuries. Arrhythmic conduction disturbances and infarct patterns can be present on the electrocardiogram (ECG). Cardiopulmonary presentations vary, and most patients lack the characteristic chest discomfort indicative of myocardial ischemia. Transient, mild paresthesias and complete and irreversible impairment of sensory or motor function, or both, can be present in patients with electrical injuries. Absent pulses, decreased peripheral perfusion, and impaired neurologic function are also seen in patients with acute vascular complications from electrical trauma.

Injuries consistent with findings of blunt trauma to the head, spinal cord, and musculoskeletal, intrathoracic, and intra-abdominal areas can be present in patients who were thrown from the energized current source, had forceful tetanic muscle contractions associated with AC injuries, or fell after losing consciousness and muscle control. Skin wounds are typically leathery or charred areas of full-thickness skin loss. The patient with lightning injury may have linear, punctate, feathery burns that often are referred to as Lichtenberg flowers.¹² The entry and exit sites are usually depressed, giving the appearance that current exploded the tissue. Underlying injury to a major muscle compartment is accompanied by edema formation. Circulatory integrity is best judged with Doppler ultrasound of distal pulses.