During my trauma rotation, we saw a man who was working on a 240 AC electrical generator and was briefly electrocuted. He had no LOC or blunt trauma associated. He had no palpitations or chest pain. He complained of 2nd degree burn to digits 2-4 of left hand. Primary survey was intact. Secondary survey revealed superficial partial thickness burns on dorsal surface of Left 2-4 middle and distal phalanges. Otherwise upper extremity was neurovascularly intact. Respiratory was intact. EKG showed incomplete RBBB, unknown if old or new. CK was 10.4. Burn was consulted and admitted patient to burn ICU for compartment checks of left upper extremity (as there was tenderness in distal forearm). As I had never cared for a patient with an electrical injury in the past, I figured I would take a closer look at the guidelines for management.
What are the simple physics of electricity?
Electricity is the flow of electrons, and can be expressed as volts (voltage) or as amps (current). The obstruction of the flow of electrons is resistance. Current = voltage/resistance.
The range of safe human exposure to electrical current is narrow. Though the threshold of perception of current is 0.2 mA, the minimum current at which electricity can cause tetany is ~10 mA. At thish current, the patient doesn't then let go of the energy source, leading to more damage. Tissues such as bone, tendon, and fat, which have the highest resistance, tend to heat up and coagulate. Therefore, damage to deeper muscles may be greater than damage to superficial soft tissues. A high voltage exposure is defined as > 1000 V. Most sources now a days are AC; car batteries remain in DC.
How do symptoms manifest to each involved organ system?
Skin = Burns
Cardiac = arrhythmias or arrest, including sinus tachy, block, ST segment abnormality, prolonged QT, Pvcs
Respiratory = can get respiratory arrest secondary to CNS affects or to respiratory muscle tetany
Vascular = get aneurysm formation and eventual tissue ischemia
Neurologic = LOC, paralysis, spinal cord injury , or peripheral neuropathy
MSK = fractures or dislocations, compartment syndrome
Renal = rhabdomyolysis and eventual renal failure
What questions I should ask in the history?
Ask bystanders and EMS about the electrical source, the voltage, the duration of contact with the source. Did the patient lose consciousness? What does he/she remember? Ask about findings at the scene, and how the patient was treated and cared for. Details on the type of appliance which caused the electrical injury, specficially the number of volts, would be most helpful.
What labs should I order?
Basic labs such as CBC, BMP. Obtain CK for rhabdomyolysis, and a urinalysis to evaluate for myoglobinuria. Get coags and type and screen if you suspect a need for surgical intervention.
Should I order an EKG or cardiac monitoring for my patient? What are indications to admit my patient?
An EKG should be performed on all patients who sustain electrical injuries, regardless of low or high voltage . Both types are at risk for cardiac injury. Those who have low voltage injuries, no findings on EKG, no LOC history, and no other injuries to require admission, can be discharged without further observation. If patient has LOC or documented dysrhythmia, admit for cardiac monitoring. CK /CKMB is not a good monitor for cardiac damage, and is likely secondary to skeletal muscle damage. It is helpful therefore, to evaluate for rhabdomyolysis. It is not clear that all patients with high voltage injuries require admission, as a matter of fact, several studies show that this doesn't correlate with likelihood of cardiac injury. However, the guidelines currently recommend observation in this scenario, and often, actual transfer to a burn center. There is no data available for how long to monitor; however the default seems to be 24 hours. Further studies would be helpful on how useful the troponin could be, the recommended duration of monitoring, and whether high voltage injuries can be discharged.
How do I care for patients with high voltage electrical injury to the upper extremity?
Transfer to a burn center. These injuries are often underestimated as there is limited external damage. If the patient develops any neurologic findings, vascular compromise, hard compartments or increased pressure, or systemic signs, highly consider surgical decompression of extremity. Of note, patient's with electrical injury are at increased risk to develop posterior shoulder dislocation; take care not to miss this on xrays.
How are lightning injuries different?
Lightning is a temporary but massive, unidirectional current, which can be > 1 million V but is only present for milliseconds. The short duration rarely causes significant burns or soft tissue destruction, but cardiac and respiratory arrest, CNS issues, and autonomic instability are more common. If there are multiple victims, highest priority should be given to those in cardiac or respiratory arrest. This is different from most mass casualty situations.
References1. Czuczman AD, Zane RD. Electrical Injuries: A review for the Emergency Clinician. Emergency Medicine Practice. EBMedicine.Net. October 2009.
2. Arnoldo B, Klein M, Gibran N. Practice Guidelines for the Management of Electrical Injuries. Journal of Burn Care and Research; 27(4): 439-447. July/August 2006.
3. Price TG, Cooper MA. Electrical and lightning INjuries. IN : Marx, Hockberger, Walls, eds. Rosen's Emergency Medicine Concepts and CLinical Practice. Philadelphia, PA: Mosby-Elsevier; 2006
4. Purdue GF, Hunt JL. EKG monitoring after electrical injury: necessity of luxury. J Trauma 1986; 26: 166.
5. Electrical Injury. American Burn and Life Support Manual.
submitted by Dr. Christina Georgopoulos
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