About 1,000 deaths are caused by electricity every year in the United States. More than 60 percent of these deaths occur in adults 15 to 40 years of age, and electrical injury is the fifth leading cause of occupational fatality. Injury results principally from the direct effect of current, the conversion of electrical energy to thermal energy in the tissues and secondary effects such as blunt trauma. The severity of injury is determined by the voltage, type of current, current intensity, duration and pathway of current, tissue resistance, contact surface, and the situation and circumstances of the accident. Electrical injuries can be classified by type of current, voltage or site of injury (see accompanying table).
|Type of current||Site of injury||Voltage||Duration of injury||Associated injuries|
Low-voltage electricity is responsible for up to 70 percent of electrical injuries and one half of deaths. Low-voltage alternating current (AC) is three times more dangerous than direct current of the same voltage. The lowest frequency in the United States is 60 Hz, but even this low level may cause muscle stimulation. When tetany occurs, the victim holds on to the source, increasing the duration of contact and severity of injury. Conversely, direct current (DC) tends to cause a single muscle contraction that throws the victim from the source. Victims of DC electrical contact may sustain less electrical injury but more blunt trauma than AC victims.
With all electrical injuries, damage progresses until the tissue becomes carbonized and resistant to current flow. The greatest damage typically occurs at the contact and ground points, but extensive damage may occur throughout the body as a result of direct or secondary effects. The most severe form of electrical injury, arc injury, occurs when the victim is part of an electrical arc or spark of current between two unconnected objects. Temperatures of 2,500°C (4,532°F) can develop, resulting in burns, and arcs also cause high-voltage shocks sufficient to break bones and cause intense muscle contractions and blunt trauma.
Some body systems are more likely to be damaged in electrical injury than others. Skin damage is common and may be extensive and deep. More importantly, the skin condition may not reflect the extent of internal tissue damage and fluid loss. Central nervous system damage is common both as a result of direct electrical damage and trauma from electrical damage. Injury to the spinal cord and central nervous system may be acute or delayed. The delayed form may result in motor and sensory deficits years after the electrical injury. Altered mental status, emotional lability, neuropathies and other conditions have been reported as acute and long-term consequences of electrical injury. A variety of eye pathologies have also been reported as acute and late effects, including corneal burns, cataracts, retinal detachment and intraocular vascular problems. Several cardiovascular problems may be caused by electrical injury, including vessel rupture, cardiac arrest and cardiac arrhythmias. The lungs and abdominal organs are rarely directly injured by electricity but may be damaged by trauma, vascular effects or other secondary effects.
In the acute situation, electrical injury victims should be managed following advanced trauma life support or cardiac support, as appropriate. The search for internal injuries must be individualized, based on the history and most likely pattern of injury. Radiographs and nasogastric decompression are common considerations, as are prophylaxis against gastrointestinal bleeding and tetanus. Patients must be carefully monitored for fluid balance and covert internal damage to vital organs. Patients may require admission to a burn unit. Outpatient management may be appropriate in asymptomatic patients following low-voltage exposure if the physical and laboratory examinations are normal. Patients being considered for outpatient management must have normal electrocardiographic screening and no evidence of myoglobin on urinalysis.