Electrical injuries are not common but can be frightening, devastating, and life changing. They may result in massive tissue destruction, changes in growth patterns, and neurologic injury, including chronic pain syndromes, permanent cognitive deficits, and high disability rate, affecting the child’s ability to learn and become a productive adult. Most victims are male. Children at most risk are exploring toddlers (12–30 months). They are more likely to suffer low-voltage injuries because they suck on extension cords or stick things into electrical outlets. Adolescents who often engage in risk-taking behavior may have injuries resulting from contact with utility poles or high-voltage power lines.^1–2

The old teaching on electrical injuries involves consideration of voltage, amperage, tissue resistance, current type, duration, and pathway (Kouwenhoven’s factors). Voltage is the difference in electric potential energy between two points and is divided arbitrarily into low and high voltage, with breakpoint at 1000 volts. Amperage is a measure of the rate of flow of electrons and is measured in amperes. Resistance is a measure of the difficulty of electron flow through a given substance. Resistance is measured in ohms.³

The body is composed of different tissues, which express a different resistance to the flow of electrical current. However, the body behaves like a volume conductor.⁴ Thus body parts exposed to the same current intensity and duration may show different degrees of heat-generated tissue injury. For a given energy, more severe injuries will occur in smaller cross-sectional areas than the same energy flowing through body parts with larger cross-sectional areas such as a thigh or the trunk.⁵ Damage can be especially high at the joints, where the low-resistance tissues (muscle) are minimized and higher-resistance tissues (tendons, bone, and cartilage) are maximal. Damage to internal organs may be more diffuse and hard to appreciate initially because of the larger cross-sectional diameter of the torso.^4,5

When the body is part of an electrical circuit, the skin is the primary resistor to electric current flowing into the body. Resistance is highly variable according to the thickness, age, and moisture,² which may explain the clinical or forensic findings in electrical injury.⁶ Overall, thickly calloused skin will have higher resistance and tend to sustain greater thermal damage at the site of contact, but it impedes the flow of energy internally. Resistance is tremendously lessened if the skin is wet with sweat or rainwater. Wet skin may show little or no local thermal damage, but it allows the majority of the energy to flow internally to the heart or other vital structures. This explains why a “bathtub” injury may show no external signs of injury while causing cardiac arrest.⁶

Current type may be either alternating or direct. Alternating current (AC) is much more dangerous than direct current (DC) at the same voltage (ventricular fibrillation was 10 times more frequent and acute myocardial infarction was 3 times more frequent in animal models).⁷ Household circuits in the United States (110/220 V) operate at 60 cycles per second (cps) and 50 cps in many foreign countries, frequencies at which neuromuscular function continues indefinitely, leading to tetany. Because the flexors of the hand are stronger than the extensors, the hand gripping an AC electrical source (called the “no-let-go” phenomenon) prolongs the duration of exposure to the electrical current,⁸ unlike DC exposure, which produces a sole convulsive contraction that expels or launches the person away from the current source. Increased duration tends to result in increased damage until the tissue is coagulated, charred, or mummified.⁴ The effect of tetanic contraction is also related to the amperage applied—the margin between the household amperage (0.001–0.01 A) that causes a buzz but usually little harm, and that capable of causing respiratory arrest (0.02–0.05 A) and ventricular fibrillation (0.05–0.10 A) is narrow.²

Even though it has been considered that the current pathway would allow determining the organs involved, it is important to remember that the current will flow with no discretion through different tissues and corporal segments, since the body behaves like a volume conductor.⁴ Also, the difficulty in differentiating the source and ground injuries, the pathway does not determine any difference between complications and mortality.^9,10 Therefore, the emergency physician and trauma surgeon must give priority to the outcome, not the current pathway.⁴

Electrical field strength has been a concept that explains and predicts electrical injury severity more accurately than the factors mentioned above.^8,11 When 20 kV are applied to a 6-ft man, causing current to ground, an internal electrical field strength of approximately 10 kV/m is generated. When a child chews on an electric cord and suffers a lip burn, the field strength is approximately the same: 110 volts applied to 1 cm of a child’s lip generates a field strength of 11 kV/m.⁴ While no one would classify the child’s injury as “high” voltage, it is a high electrical field strength and it produces the same tissue destruction in a small, localized area that “high voltage” would produce in a 6-ft man (Fig. 139-1).

In developing countries, there are large numbers of deaths in the home, both because families tend to consider household current to be “safe” and because there is little prehospital care available.^12–14 However, the electrical field strength and presence of AC in low-voltage exposure could explain a greater number of deaths due to low-voltage household accidents compared to high-voltage exposure in workplaces or on the street.^12,13

MECHANISMS OF INJURY

Several common mechanisms of injury exist (Table 139-1). There is a pure electrical mechanism which is produced due to direct contact with the electrical source or grounding points or when being part of the circuit indirectly, when energy jumps from a source to a nearby person (electric arc). An electrical field may cause cell membrane disruption (electroporation), protein transmembrane configuration changes, or induce a transmembrane electric action potential.^8,11 Cell death occurs due to alteration of the intracellular milieu and the failure to restore homeostasis, which is not produced immediately post electrical discharge but over an extended period of time. The more vulnerable cells are the muscle and nerve cells, which explains many of the clinical findings in these patients.³

A second mechanism (electrothermal) produces the immediate death of tissues due to its thermal effects, by the transformation of electrical energy into thermal energy.^3,4,8 According to Joule’s law of heating, heat produced is equal to the product of the square of the current, resistance of the conductor, and the duration of time for which it flows (heat = current² × resistance × time). This process is responsible for the coagulative necrosis and tissue desiccation, mainly in high voltage injuries.

A third mechanism (thermoacoustic) is produced by an electric arc, which is an electric current between two points separated by a gas, and it is characterized by light, pressure wave, and very high temperature capable of melting or vaporizing most materials.⁸ Burns may be caused by the heat of the arc itself, electrothermal heating due to current flow by indirect contact, or by flames if clothing is secondarily ignited. Blunt injury occurs by blast effect, and in DC o high voltage exposure by fall or thrown. Fractures or dislocations may occur.

ANATOMIC SITES OF INJURY

Clinical manifestations of electrical injury are highly variable. While electrical injuries are often classified under burns, higher-energy injuries may more closely resemble crush injuries caused by muscle destruction, compartment syndromes, and myoglobin production. Some victims of electrical injury may have very little external damage while sustaining serious underlying tissue damage.

Burns are found in nearly all non–water-related electrical injuries.¹ However, absence of burns does not rule out exposure to electricity. The most common areas of injury are the hand, skull, and foot.¹ Subcutaneous tissues, muscle, nerves, and blood vessels also suffer thermal damage. Tissue that initially appears viable may later die because of the electrothermal mechanism as well as ischemia caused by vascular wall damage, edema, and thrombosis, which may affect either inflow or outflow of blood to tissue.³

A common injury for very young children is incurred by sucking on the ends of extension cords, resulting in severe orofacial injuries. Burns are often full thickness, involving the lips and oral commissure.^15,16 These burns are initially bloodless and painless. As the eschar separates in 2 to 3 weeks, severe bleeding can occur from damage to the labial, facial, or even carotid arteries. There can be alveolar bone damage and germinal tooth loss, growth retardation, devitalization of teeth, and microstomia from extensive scarring.

Cardiac effects occur when current passes directly through the heart, and it can induce ventricular tachycardia, ventricular fibrillation, or asystole. A wide variety of arrhythmias can occur, including supraventricular tachycardia, extrasystoles, right bundle branch block, and complete heart block. The most common electrocardiographic (ECG) abnormalities are sinus tachycardia and nonspecific ST-T wave changes. Most rhythm disturbances are temporary.¹⁷ Myocardial infarction and ventricular perforation have been reported. Syncope, as a cardiac or neurologic manifestation, occurs in up to 33% of the children affected.¹⁸

Vascular injuries include thrombosis, vasculitis with necrosis of large vessels, vasospasm, and late aneurysm formation. Maximal decrease in blood flow will occur in the first 36 hours. Strong peripheral pulses do not guarantee vascular integrity.³

Acute renal failure may occur from hypoxia and hypovolemia during resuscitation in combination with myoglobin released by extensively damaged muscle or hemoglobin from hemolysis.¹⁹ In rhabdomyolysis, myoglobin becomes concentrated along the renal tubules, a process that is enhanced by volume depletion and renal vasoconstriction mediated by the activation of the renin–angiotensin system, vasopressin, and the sympathetic nervous system. The myoglobin precipitates when it interacts with the Tamm–Horsfall protein, a process favored by acidic urine.²⁰ Kidney damage may also occur from blunt trauma, hypotension, hypoxic ischemic injury, cardiac arrest, and hypovolemia. Oliguria, albuminuria, hemoglobinuria, and renal casts may be seen transiently.

Neurological Injuries: Immediate CNS effects include loss of consciousness, seizure, agitation, amnesia, deafness, seizures, visual disturbance, and sensory complaints. Vascular and blunt injury damage may result in epidural, subdural, or intraventricular hemorrhage. Within several days, the syndrome of inappropriate antidiuretic hormone secretion (SIADH) may lead to cerebral edema and herniation. Peripheral nerve injury from vascular damage, thermal effect, or direct action of current may occur, and it can be progressive. A variety of autonomic disturbances may also occur. Late involvement of the spinal cord may produce ascending paralysis, amyotrophic lateral sclerosis, transverse myelitis, or incomplete cord transection.²¹ Cataracts can be seen in any electrical injury involving the head or neck. Victims may suffer depression, flashbacks, attention deficit disorder, sleep problems, and other cognitive difficulties that can affect learning and school performance as well as social function within the family or school.²²

Passage of current through the abdominal wall can cause Curling’s ulcers in the stomach or duodenum. Other injuries described include evisceration, stomach or intestinal perforation, esophageal stricture, and electrocoagulation of the liver or pancreas.²³

Blunt trauma or tetanic muscle contractions can cause fractures or dislocations. Amputation of an extremity is necessary in 35% to 60% of survivors of high-energy injury caused by extensive underlying injuries. Infections frequently occur in necrotic tissue.

MANAGEMENT

Prehospital Care

Extrication is extremely dangerous until the power source is disconnected. Victims should be treated both as burn victims and as blunt trauma patients, with special attention given to spinal immobilization. Transport to a health care facility should not be delayed.^24,25

Several reports have shown that most deaths occur at the scene of the accident due to cardiac arrest with asystole, arrhythmias such as tachycardia or ventricular fibrillation, or secondary to hypoxia from respiratory arrest due to compromise of the respiratory center at the brain stem or oxygenation and ventilation disorder caused by respiratory muscle tetany.^10,26 These patients may benefit from early cardiopulmonary resuscitation measures either by lay personnel or prehospital systems.²⁷ In events with multiple victims, the main priority is the critical patient even without vital signs. Given the common absence of related pathologies and young age, these patients may show good prognosis, even in long resuscitation processes.^18,27