Laboratory Studies
In all patients with more than a trivial electrical injury and/or exposure, the following tests should be considered:
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CBC count: Obtain values for hemoglobin, hematocrit, and white blood cell count.
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Electrolytes: Assess sodium, potassium, chloride, carbon dioxide, blood urea nitrogen, and glucose.
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Creatinine: There is a high risk of rhabdomyolysis/myoglobinuria in electrical injuries; mortality in one study was 59% for patients with acute renal failure. [31]
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Urinalysis: Obtain values for specific gravity, pH, hematuria, and urine myoglobin if the urinalysis is positive for hemoglobin.
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Serum myoglobin: If urine is positive for myoglobin, a serum level should be obtained.
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Arterial blood gas: This is obtained for patients needing ventilatory support or those with severe rhabdomyolysis who require urine alkalinization therapy.
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Creatine kinase (CK) levels: This level may be extremely elevated in patients with massive muscle damage from high-voltage injuries. Normal CK values published by the laboratory may be low for typical construction and electrical workers whose vocation involves heavy exercise. Some evidence suggests that initial CK levels may help predict which patients could benefit from early fasciotomy to prevent subsequent amputations. [10] CK-MB subfractions are also often elevated in electrical injuries, but their significance in the setting of electrical injuries is not known. [3] CK-MB fractions and troponin should be checked if the current pathway involved the chest/thorax, if the patient has any signs of ischemia or arrhythmia on ECG, or if the patient has specific complaints of chest pain. One retrospective review created a decision rule for clinical identification of patients likely to have rhabdomyolysis. [32] Multivariate modeling revealed that high-voltage exposure, prehospital cardiac arrest, full-thickness burns, and compartment syndrome were associated with myoglobinuria. Defining "positive" as two or more of these findings has a sensitivity of 96% and negative predictive value of 99%. Initial CK and myoglobin levels correlate with burn size, ventilator days, hospital length of stay, need for surgical intervention, sepsis, and mortality. [33]
Imaging Studies
Choice of imaging studies is dictated by the presence of blunt trauma, altered mental status, cardiac or respiratory arrest, and type of electrical exposure. Studies to be considered are as follows:
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Chest radiography - Any patient with cardiac or respiratory arrest, shortness of breath, chest pain, hypoxia, CPR at the scene, or fall/blunt trauma
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Head computed tomography - Any patient with altered mental status, significant traumatic mechanism, seizure, loss of consciousness, or focal neurologic deficits
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Cervical/spine imaging - Patients with loss of consciousness or significant trauma should be cervical spine immobilized and imaged accordingly. Clinical clearance may be appropriate for some patients with normal mental status without significant injuries. Patients with focal neurologic deficits or evidence of spinal cord injury should undergo full spinal imaging.
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CT/ultrasonography - Depending on the amount of trauma sustained and the pathway of the current exposure, patients may require further imaging to evaluate for internal injuries. Imaging modality varies depending on suspected injury and availability.
Other Tests
ECG/cardiac monitoring
All adult patients should have an initial ECG and cardiac monitoring in the ED. The duration of monitoring depends on the circumstances of the exposure; any patients with chest pain, arrhythmia, abnormal initial ECG, cardiac arrest, loss of consciousness, transthoracic conduction, or history of cardiac disease should undergo monitoring. No definitive guideline is available on duration of monitoring for adults, but patients are unlikely to develop significant arrhythmias after 24-48 hours if they have no other significant injuries. Several large reviews have not identified risk of delayed arrhythmia among patients with low-voltage exposure and no arrhythmia upon initial presentation. One such review of 196 exposures concludes that admission for cardiac monitoring is not indicated for such patients. [34]
Several studies have shown that low-voltage (household) exposures in patients with no cardiac complaints and a normal initial ECG can be safely discharged. [35] It is unclear how this applies to patients with preexisting heart disease. In the pediatric population, healthy children with household current exposures (120 to 140V, no water contact) can be safely discharged if they are asymptomatic, without a VF or cardiac arrest in the field, and have no other injuries requiring admission. [26, 36]
Procedures
Obtain intravenous access in all adult patients with electrical injuries. Consider central access in any patient with significant trauma, large burns, cardiac or respiratory arrest, or loss of consciousness.
Fasciotomy of a burned extremity may be required in high-voltage injuries or prolonged low-voltage injuries. Obtain early surgical consultation, preferably with experience in burn management, early in the treatment of any patient with a high-voltage burn, since appropriate early fasciotomies may prevent subsequent amputations. If emergently indicated, fasciotomy should not be delayed.
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Arcing electrical burns through the shoe around the rubber sole. High-voltage (7600 V) alternating current nominal. Note cratering.
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Contact electrical burn. This was the ground of a 120-V alternating current nominal circuit. Note vesicle with surrounding erythema. Note thermal and contact electrical burns cannot be distinguished easily.
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Contact electrical burns, 120-V alternating current nominal. The right knee was the energized side, and the left was ground. These are contact burns and are difficult to distinguish from thermal burns. Note entrance and exit are not viable concepts in alternating current.
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Electrical burns to the hand.
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Electrical burns to the foot.
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High-voltage electrical burns to the chest.
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Superficial electrical burns to the knees (flash/ferning).
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Energized site of low-voltage electrical burn in a 50-year-old electrician.
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Grounded sites of high-voltage injury on the chest of a 16-year-old boy who climbed up an electric pole.
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Energized site of the high-voltage injury depicted in Media File 9 (16-year-old boy who climbed up an electric pole).
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Entrance site of a low-voltage injury.
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Grounded sites of a low-voltage injury in a 33-year-old male suicide patient.
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Grounded site of a low-voltage injury in the same 33-year-old male patient depicted in Media File 12.
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Grounded sites of low-voltage injury on the feet.
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A histologic picture of an electrical burn showing elongated pyknotic keratinocyte nuclei with vertical streaming and homogenization of the dermal collagen (40X). Courtesy of Elizabeth Satter, MD.
Tables
Effect |
Current (milliamps) |
Tingling sensation/perception |
1-4 |
Let-go current – Children |
3-4 |
Let-go current - Women |
6-8 |
Let-go current – Men |
7-9 |
Skeletal muscle tetany |
16-20 |
Respiratory muscle paralysis |
20-50 |
Ventricular fibrillation |
50-120 |
