Thanks to Dr. Regan for putting together this summary of our last EM Critical Care conference!
The Case: Man found unresponsive underneath subway train with right hip dislocation, electrocution by third rail, multiple burns and rhabdomyolysis.
Electrical Injuries
Voltage:
-High voltage is >1000, low voltage is <1000
-Outlets in U.S. homes have 100V, European home 220V
-Power lines > 100,000 V, Lightning >1 million V
Direct Current (DC):
-travels in one direction
-used in 3rd rail in subway and batteries
Alternating Current (AC):
-periodically reverses direction
-can cover longer distances than DC
-used in appliances, car motors, radio towers
-is more dangerous than DC at the same voltage (tetanic contraction in DC tends to throw the person away from the source)
Electrocution Injuries:
-Cardiac:
- 15% incidence of arrhythmias, Vfib most common cause of fatal arrhythmia
- necrosis of myocardium
- DC/lightning cause asystole, AC causes Vfib
-Renal:
- acute renal failure
- rhabdomyolysis: treat with bicarb drip to alkalinize urine
-Neuro:
- both central and peripheral nervous systems can be affected
- LOC, weakness, respiratory depression, autonomic dysfunction, sensory & motor findings
-Derm:
- degree of external injury does not correlate with internal injuries
- all types of burns
- pediatric oral burns: watch for bleeding from labial artery injury; all should be referred to plastic surgery for follow-up
-MSK:
- bone generates greatest amount of heat–>periosteal burns, osteonecrosis
- tissue necrosis can lead to compartment syndrome
- traumatic injuries from blunt trauma (especially lightning and high voltage DC), ie: joint dislocations
-Other:
- tympanic membrane rupture
- cataracts
- in lightning injuries, respiratory arrest due to tetanic muscle contraction (reverse triage is important in these patients)
Disposition:
-Low voltage (i.e. house): no cardiac complaints and normal EKG can be safely discharged
-High or Low voltage with significant injuries
- treat burns, consider transfer to burn center if necessary
- treat associated blunt traumatic injuries
- in asystolic arrest, secure airway with ACLS. ROSC is common.
References
- Browne BJ, Gaasch WR. Electrical injuries and lightning. Emerg Med Clin North Am. 1992 May; 10(2): 211-29.
- Koumbourlis AC. Electrical Injuries. Crit Care Med. 2002;30(11 Supp):S424-30.
- Lee RC. Injury by electrical forces: pathophysiology, manifestations and therapy. Curr Probl Surg. 1997 Sep:34(9): 677-764.
- Rabban J, Adler J, et al. Electrical injury from subway third rails: serious injury associated with intermediate voltage contact. Burns. 1997 Sep;23(6): 515-8.
- Wright RK, Davis JH. The investigation of electrical deaths: a report of 220 fatalities. J Forensic Sci. 1980 Jul;25(3): 514-21.
Jay Khadpe MD
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