Sachita P. Shah
ELECTRICAL INJURIES EPIDEMIOLOGY
At-risk groups for electrical injuries include young children (low-voltage injuries) from contact with electrical cords and appliances, and adult professionals working with high-voltage electricity.
PATHOPHYSIOLOGY
Electrical injuries are arbitrarily classified as low voltage (≤1000 V) and high voltage (>1000 V).
Current can either be continuous in one direction (direct current, DC) or be in alternating directions (alternating current, AC).
Factors associated with severity of electrical injuries include the amount, duration, type (AC or DC), the current path through the body, and environmental factors (eg, water immersion).
Electrical energy in tissues can cause burns (entry and exit), thermal heating, flash and arc burns, blunt trauma, and muscular tetany.
Low-voltage AC current will cause muscular tetany, causing the injured person to continually grasp the source, increasing contact time.
High-voltage AC and DC currents cause a single violent muscular contraction, which tends to throw the victim from the source, thus increasing the risk of blunt trauma and blast injuries.
Electricity causes damage by direct tissue damage from electrical energy, thermal damage from the heat generated by the resistance of tissue, and mechanical injury due to fall or muscular tetany.
Energy is greatest at the contact point; thus the skin often has the greatest visible damage, although evaluation for deeper injury must be performed.
CLINICAL FEATURES
As current flows through the body, the greatest damage is sustained by nerves, blood vessels, and muscles causing coagulation necrosis, neuronal death, and damage to blood vessels. As a result, the overall picture often resembles a crush injury more than a thermal burn.
Traumatic injuries frequently accompany electrical injuries.
Specific complications of electrical injuries are summarized in Table 128-1.
Immediate life-threatening features include cardiac arrhythmias including ventricular fibrillation (low voltage) and asystole (high voltage), respiratory arrest, seizures, and severe burns.
Oral burns in children may have delayed labial artery bleeding (up to 2 weeks later).
TABLE 128-1 Complications of Electrical Injuries
DIAGNOSIS AND DIFFERENTIAL
Diagnosis of electrical injury is usually based on history.
In unclear cases, characteristic skin or oral lesions in children may be helpful.
Laboratory and radiographic evaluation of high-voltage injures should follow standard trauma guidelines.
The creatine kinase (CK-MB) may be elevated without myocardial damage due to extensive muscle injury with potential for rhabdomyolysis. Urine myoglobin and total CPK should be obtained.
Electrocardiogram (ECG) may show atrial or ventricular arrhythmias, bradyarrhythmias, prolonged QT intervals, or ST-T wave abnormalities
Computed tomographic (CT) scanning of the head is indicated for those with severe head injury, coma, or unresolving mental status changes.
EMERGENCY DEPARTMENT CARE AND DISPOSITION
The airway, breathing, and circulation should be stabilized. Spinal immobilization should be instituted for any unwitnessed events or when there is a potential for spine injury.
High-flow oxygen should be administered by face mask.
Patients should have continuous cardiac monitoring, pulse oximetry, noninvasive blood pressure monitoring, and preferably two large-bore IV lines.
Ventricular fibrillation, asystole, or ventricular tachycardia should be treated by standard Advanced Cardiac Life Support (ACLS) protocols. Other dysrhythmias are usually transient and do not need immediate therapy.
IV crystalloid fluid should be given with an initial bolus of 20 to 40 mL/kg over the first hour. Fluid requirements are generally higher than those of thermal burn patients.
Monitor for rhabdomyolysis, compartment syndrome, and renal failure. Treat rhabdomyolysis with aggressive fluid rehydration aiming for a urine output of 2 mL/kg/h.
Tetanus prophylaxis should be given. Prophylactic antibiotics are not necessary initially unless large open wounds are present.
Seizures are treated with standard therapy.
It is appropriate to consult a general surgeon if there is evidence of systemic or deep tissue injury. These patients may require formal wound exploration, deb-ridement, fasciotomy, and long-term care.
Children with oral injuries should be evaluated by an ENT specialist or plastic surgeon.
All pregnant patients should undergo obstetric consultation for admission and fetal monitoring.
Table 128-2 summarizes admission criteria. Patients with an unclear history of exposure or degree of injury should be admitted.
Children with isolated oral injuries or isolated hand wounds can usually be discharged. Parents should be given instructions for controlling delayed labial artery bleeding.
Asymptomatic patients with household voltage exposure (110-220 V), a normal ECG, and a normal examination may be discharged.
Electronic control devices, such as the cattle prod, stun gun, and the TASER®, emit electrical pulses that induce involuntary muscle contraction, neuromuscular incapac-itation, and/or pain. Serious injury is rare, and cardiac monitoring is usually not necessary.
TABLE 128-2 Indications for Admission for Patients with Electrical Injuries
High voltage >600 V
Symptoms suggestive of systemic injury
Cardiovascular: chest pain, palpitations
Neurologic: loss of consciousness, confusion, weakness, headache, paresthesias
Respiratory: dyspnea
Gastrointestinal: abdominal pain, vomiting
Evidence of neurologic or vascular injury to a digit or extremity
Burns with evidence of subcutaneous tissue damage
Dysrhythmia or abnormal electrocardiogram
Suspected foul play, abuse, suicidal intent, or unreliable social situation
High-risk exposures
Associated injuries requiring admission
Comorbid diseases (cardiac, renal, neurologic)
LIGHTNING INJURIES
EPIDEMIOLOGY
There are about 300 lightning injuries reported each year in the United States, with approximately 100 deaths.
Unlike electrical injuries, extensive tissue damage and renal failure are rare, although as many as 75% of survivors sustain significant morbidity and permanent sequelae.
Sports, particularly water sports, and transportation are associated with increased risk of lightning injury.
PATHOPHYSIOLOGY
Lightning is DC imparting a single extremely high-voltage discharge of energy.
Lightning injures can result via direct strike, side flash (current flows over from another struck object), contact strike (a person touching a struck object), ground current (passing through the ground and transferred to a standing person), or step potential (ground strike passes up a person’s leg and down through the other leg).
CLINICAL FEATURES
Lightning injuries can vary in severity depending on the circumstances of the strike, and range from minor injuries to cardiac or respiratory arrest.
Minor injuries include confusion, amnesia, short-term memory problems, headache, muscle pain, paresthesias, tympanic membrane damage, and temporary visual or auditory problems.
Most patients with minor lightning injuries have a gradual improvement and few long-term sequelae.
Feathering or fern-shaped burns on the skin are pathognomonic of lightning.
Complications associated with lightning injuries are summarized in Table 128-3.
TABLE 128-3 Complications Associated with Lightning Injuries
DIAGNOSIS AND DIFFERENTIAL
The diagnosis of lightning injury is based on history and should be considered in a patient found unconscious or in arrest who was outside during appropriate weather conditions.
Pupillary dilatation or anisocoria may occur and has no prognostic value.
Ruptured tympanic membranes or fernlike erythema-tous skin markings should alert the physician to potential lightning injury.
Misdiagnoses include stroke or intracranial hemorrhage, seizure disorder, and cerebral, spinal cord, or other neurologic trauma.
EMERGENCY DEPARTMENT CARE AND DISPOSITION
Aggressive resuscitation measures are indicated, as survival has been reported after prolonged respiratory arrest.
Respiratory arrest may outlast initial cardiac arrest, and adequate ventilation can prevent hypoxic injury until return of spontaneous circulation.
Spinal immobilization should be used in unwitnessed events or when there is potential spine injury.
Continuous cardiac monitoring, pulse oximetry, non-invasive blood pressure monitoring, and at least one large-bore IV should be utilized.
Hypotension is unexpected and should prompt investigation for hemorrhage.
High-flow oxygen should be administered by face mask.
Ventricular tachycardia or fibrillation and asystole should be treated with standard ACLS protocols.
Fluid resuscitation is usually unnecessary.
Tetanus prophylaxis should be given.
Seizures may be treated with standard therapy.
Those with moderate or severe injuries should be admitted to a critical care unit with appropriate consultation.
Most patients with minor injuries should be admitted for close monitoring of cardiac and neurologic status.
All pregnant patients should be admitted and undergo fetal monitoring.
For further reading in Tintinalli’s Emergency Medicine: A Comprehensive Study Guide, 7th ed., see Chapter 126, “Electrical and Lightning Injuries,” by Sachita R Shah.