Surface wounds may not reflect massive deep tissue injuries after electrical trauma.
Recent studies suggest that decompression should be performed for the usual signs of compartment syndrome instead of the traditional teaching of immediate empirical releases after electrical burns.
The decision for limb salvage versus amputation should be made as early as possible.
Electrical injuries have occurred since human beings have been harnessing electricity for their own gain. The first recorded fatal electrical injury occurred in 1879 in Lyons, France.
Currently, 52,000 patients are admitted each year for electrical burns. This composes 3% to 6.7% of all admissions to burn centers in the United States. Unfortunately, about 1000 of these injuries prove to be fatal annually. As for the upper extremity, the majority of high-voltage electrical injuries are work-related.
High voltage is defined as greater than 1000 V and is associated with immediate severe tissue damage. However, severity of tissue injury is related to current more than voltage. Current may be determined from Ohm’s law with a known voltage from an electrical source and tissue resistance ( Fig. 100-1 ). Various tissues have different resistances to electrical flow, with neural tissue having the least resistance, followed by blood vessels, muscle, skin, and finally bone having the greatest resistance. The epidermis dominates the resistance, with 95% of the voltage drop occurring over the epidermis. The palms of the hands may have up to three times more epidermal thickness than other parts of the body, thus increasing the resistance threefold. Wet skin decreases resistance and increases the current for any given voltage. This fact is demonstrated with low-voltage electrocution accidents in bathtubs. As electrical energy travels down the arm, specific regions such as the wrist and elbow are affected more because of the resistance of the tissue (bone and tendon) and decreased cross-sectional area. Typically, current will flow from the hand and travel through low-resistance nerves, blood vessels, and muscle to a grounded area such as the foot.
Electricity injures human tissue through various mechanisms. High voltage carries current through an arc (current flowing through air) before physical contact is ever made with the electrical source. The high temperatures of the arc will vaporize skin. Arcing may also lead to ignition of clothing, leading to thermal burn injuries as well.
Current travels as electrons in conductors but is converted to ions in the human body during an electrical injury. Subsequently, heat is released and toxic chemicals are produced, both of which result in tissue injury. It is this heat that appears to be the primary mediator of tissue damage in electrical injuries. In addition, strong electric fields are known to cause defects in cell membranes in a process called electroporation. Electroporation affects large cells oriented in the direction of the electric field such as skeletal, nerve, and vascular tissue.
The type of current also affects the injury pattern. In general, alternating current (AC) is deemed more dangerous, since it is associated with a higher likelihood of cardiac and respiratory arrest. Furthermore, someone holding an AC electrical wire will be unable to release it as involuntary spasms of the flexors (stronger than extensors) are activated, thus increasing the total time of electrical injury. On the other hand, direct current causes a single muscle contraction that typically blows the victim away from the electrical source.
Various organ systems are damaged during an electrical injury. Muscle is the major tissue through which current flows and receives the bulk of the damage. This rapid breakdown of skeletal muscle is called rhabdomyolysis. Rhabdomyolysis occurs when electrical energy is converted to heat energy, which denatures proteins and damages cell membranes in skeletal muscle. Deep muscle is more severely affected, since it cannot cool as rapidly as superficial tissue. The breakdown of muscle releases nephrotoxic products such as myoglobin into the bloodstream.
The cardiovascular system is also affected by electrical injuries. Electricity may cause cardiac muscle necrosis, coronary vascular injury, and dysrhythmia. Cardiac injuries are more severe for AC and high-voltage injuries. High-voltage current is associated with asystole, whereas low-voltage current is associated with ventricular fibrillation. Also, peripheral vessels are prone to progressive thrombosis and occlusion after electrical injuries.
The tetanic contractions caused by electrical injuries frequently cause fractures and dislocations of the upper extremity. Similarly, spasm of the paraspinal muscles may cause vertebral compression fractures.
Compartment syndrome is common and results from increased vascular permeability and release of intracellular fluids. Care must be taken when evaluating for compartment syndrome as peripheral nerves may be injured, clouding diagnosis.
Initial evaluation and treatment is aimed toward cardiac and trauma care. Resuscitation from cardiopulmonary compromise is always the first priority. A trauma workup including evaluation of the cervical spine is required. Vascular evaluation should be included with particular attention to the area of contact with the electrical source. A full neurologic examination should be performed to evaluate for any peripheral or central neuropathies. All patients should have an electrocardiogram in addition to continuous cardiac monitoring for 48 hours, as cardiac arrhythmia may develop and high potassium concentrations (hyperkalemia) from tissue necrosis may affect cardiac function. A detailed history should be taken, including type of voltage, length of contact, protective gear, and any ensuing blunt trauma such as falls.
Laboratory tests should include a complete blood count to look for anemia caused by electrical lysis of red blood cells. Serum electrolytes should be checked, since release of intracellular contents of blood cells and skeletal muscle may lead to abnormalities. Urine should be checked for myoglobin and hemoglobin.
Aggressive fluid resuscitation is necessary to manage third spacing of fluids. Fluids are also needed to prevent the precipitation of hemochromes from lysed blood and muscle cells in the renal tubules. Urine output should be maintained at 0.5 mL/kg/hr for adults and should be doubled if myoglobin or free hemoglobin is found in the urine. For oliguria unresponsive to intravenous fluids or if hemochromes do not clear, mannitol may be administered at a rate of 12.5 mg/L preceded by a 25-mg bolus.
Following resuscitation and stabilization, attention should then proceed to the upper extremity. The skin should first be evaluated. Contact burns will have a central charred area surrounded by erythema, while flash and flame burns will appear as other thermal injuries ( Fig. 100-2 ). Arcing burns are seen in the axilla, antecubital fossa, and distal forearm. One must be cognizant that the surface wounds may not reflect the underlying deep tissue injury. Appropriate tetanus and antibiotic prophylaxis should then be administered.