EM@3AM – Electrical Injuries

Author: Rachel Bridwell, MS4 (USUHS) & Erica Simon, DO, MHA (@E_M_Simon, EMS Fellow, USAF) // Edited by: Alex Koyfman, MD (@EMHighAK, EM Attending Physician, UTSW / Parkland Memorial Hospital) and Brit Long, MD (@long_brit, EM Attending Physician, San Antonio, TX)

Welcome to EM@3AM, an emdocs series designed to foster your working knowledge by providing an expedited review of clinical basics. We’ll keep it short, while you keep that EM brain sharp.


A 38-year-old male construction worker presents to the emergency department following an electrical injury. One hour prior to presentation, while nailing plywood at a residential job site, the man accidentally touched an electrical connector with his un-gloved left hand, and was “shocked worse than anytime before.” The patient denies all current symptoms, but “…given how bad the shock was…he wanted to be sure that everything was ok.” Review of systems is remarkable for a recent upper respiratory infection.

Triage vital signs (VS): BP 122/81, HR 67, T 99.9 Oral, RR 14, SpO2 99% on room air.

Pertinent physical examination findings:
Neurological: Cranial nerves II-XII intact. Deep tendon reflexes (triceps, biceps, patellar) 2+ bilaterally. Muscle strength 5/5 upper and lower extremity large muscle groups. Two-point discrimination intact distally in all extremities. Capable of tandem gait.
HEENT: No obvious evidence of trauma. Tympanic membranes intact bilaterally.
CV: Regular rate and rhythm.
Integumentary: Without findings.

EKG: Heart rate: 68 beats per minute. Normal sinus rhythm. Normal axis. Normal intervals. No ST-T wave changes.

What’s the next step in your evaluation and treatment?


Answer: Electrical Injury1-8

  • Epidemiology:
    • Injuries occur in three age groups:1
      • Toddlers => household electrical sockets, appliances, electrical cords.
      • Adolescents => risk-taking behavior.
      • Adults who work with electricity (e.g. construction, utility workers, etc.) => Occupational death rate 1:1,000 in the U.S.2
    • Lightning strike: Most common among American males ages 20-44 years.Lightning strikes are responsible for 50-300 deaths in the U.S. annually (occurring most often in Florida and along the Gulf of Mexico).4
  • Classification:
    • Generally accepted definitions:1
      • Low voltage: ≤ 1000 volts (V)
        • Household outlets in the United Stated: typically 110 V (large appliances may utilize 220 V circuits).
      • High voltage: > 1000 V
        • Power lines: > 7000 V
      • Alternating current (AC): electrical source with changing direction of current flow (household outlets).
      • Direct current (DC): electrical source with unchanging direction of current flow (lightning).
  •  Pathophysiology:
    • Mechanisms of electrical injury:
      • Direct tissue damage (entry/exit sites)
      • Internal thermal heating
      • Induced muscle contraction (see below)
      • Blunt trauma
      • Flash Burns
      • Arc Burns
    • Mechanisms of lightning injury:
      • Direct strike
      • Contact strike: lightning strikes an object that the victim is touching.
      • Side flash: lightning strikes an object => electrical current traverses the air => strikes victim.
      • Ground strike: lightning hits the ground => energy is transferred to a person standing in the vicinity.
    • Severity of injury determined by:
      • Type of current (AC vs. DC): Low voltage AC => muscular tetany => increased duration of contact.
      • Duration of contact
      • Voltage
      • Resistance of tissues (high resistance: bone, tendon, fat; intermediate resistance: skin; low resistance: nerves, blood vessels, muscles).
      • Current intensity (amperage)
      • Environmental circumstances (rain, etc.)
      • Path of the current
  •  Clinical Presentation: Cardiac arrest (DC => asystole, AC => VF), altered mental status (often transient), weakness/paresthesias of the extremities, inability to ambulate (typical of lightning injury = keraunoparalysis), seizures, burns, vision impairment (ocular involvement), hearing loss/vertigo (TM rupture), fractures/dislocations/blunt trauma (victim thrown from the location of injury; occurs in up to 1/3 of individuals struck by lightning).5
  • Evaluation:
    • Assess ABCs and obtain VS.
      • Note: If on-scene following an electrical injury:
        • Assess scene safety:
          • Injury secondary to an electrical power source => ensure that the power is turned off.
          • Lightning => caution as additional strikes are possible. The majority of lightning strikes are associated with blunt trauma => consider spinal immobilization as appropriate.1
    •  Obtain an EKG and initiate continuous cardiac monitoring:
      • Electrical injuries may result in any type of dysrhythmia (QT prolongation is most frequently cited; EKG changes are uncommon if exposure < 120 V).6
    •  Perform a thorough history: Assess the likelihood of high vs. low voltage electrical exposure/injury. Question regarding equipment/grounding: gloves, rubber-soled shoes, etc.
    •  Perform a complete physical examination. The following findings are associated with electrical injury/lightning strike:
      • HEENT: Skull and C-spine injuries resulting from high-voltage contact/blunt trauma; TM rupture; anisocoria, Horner’s syndrome, mydriasis, decreased visual acuity secondary to corneal burns, retinal detachment, uveitis, or intraocular hemorrhage.
        • Pediatric patients: oral burns (sucking/chewing on electrical cords).
      • Cardiovascular: lightning injuries may result in cardiogenic shock and Takotsubo cardiomyopathy.6
      • Musculoskeletal: extremity weakness; weak, blue, mottled lower extremities (keraunoparalysis); tense compartments (compartment syndrome).
      • Integumentary: burns, Lichtenberg figures (feathering burns specific to lightning injuries).
    •  Laboratory evaluation:
      • CMP, CPK (rhabdomyolysis), lactate (assess hypoperfusion in shock states/severe burns), troponin (myocardial injury), UA (myoglobinuria), β-hCG as appropriate.
    •  Imaging:
      • Neurological signs/symptoms: Head CT => as current traverses the skull => heat-induced coagulation => subdural/epidural hematoma or intraventricular hemorrhage
      • C-spine imaging for patients with AMS or significant cranial injuries.
  •  Treatment:
    • On scene following a lightning strike: patient in cardiac arrest => defibrillate. Aggressively resuscitate (reverse triage).
    • Initiate fluid resuscitation (address rhabdomyolysis/volume losses secondary to large surface area burns).
    • Significant muscle damage/burns: administer tetanus booster (burns are prone to tetanus infection).1
    • Burns: assess body surface area involvement. Transfer for burn specialty consultation as appropriate (circumferential burns, genital burns, burns to the hands, etc.).
      • Pediatric oral burns: refer to burn specialty/plastics for evaluation/treatment as appropriate.
  •  Disposition:
    • Asymptomatic patient having experienced a low voltage electrical injury => discharge with return precautions (delayed neurologic symptoms may occur => portends a poor outcome).1
    • Consider observation for individuals at higher risk for severe injury secondary to low voltage exposures: patients whose skin was wet during the injury, patients reporting having experienced tetany, and those in whom electrical current was thought to have traversed the chest (potential cardiac injury).
    • Patients reporting mild symptoms with normal EKGs and laboratory studies (no evidence of rhabdomyolysis), and absent burns requiring consultation: suggested discharge following 4-6 hours of cardiac monitoring.1
    • Pediatric oral burns: follow-up as dictated by specialty consultation.  Parental guidance regarding delayed labial artery bleeding (5-7 days post injury).1
    • Pregnant patients:8
      • First trimester: confirm fetal heart tones; spontaneous abortion precautions.
      • Second and third trimester: confirm fetal heart tones and consult OB => increased risk of placental abruption.
    • All patients exposed to high voltage: admit.
  • Pearls:
    • Symptomatic victims of electrical injury = high risk for compartment syndrome.
    • Approximately 75% of individuals having survived a lightning strike experience permanent sequelae (e.g. sleep disturbance or chronic pain).1
    • Delayed cataract formation has been reported in 6% of victims of lightning strikes.1

 

References:

  1. Colwell C. Lightning Injuries. In Emergency Medicine: Clinical Essentials. 2ed. Philadelphia, Saunders. 2013; 132:1148-1152.e1.
  2. Ore T, Casini V. Electrical fatalities among US construction workers. J Occup Environ Med. 1996; 38:587-592.
  3. Adekoya N, Nolte K. Struck-by-lightning deaths in the United States. J Environ Health. 2005; 67:44-50.
  4. Krider E, Uman M. Cloud-to-ground lightning: mechanisms of damage and methods of protection. Semin Neurol. 1995; 15:227-232.
  5. Blount B. Lightning Injuries. Am Fam Physician. 1990; 42:405-415.
  6. Arrowsmith J, Usgaocar R, Dickson W. Electrical injury and the frequency of cardiac complications. Burns. 1997; 22:576-578.
  7. Dundon B, Puri R, Leong D, et al. Takotsubo cardiomyopathy following lightning strike. Emerg Med J. 2008; 25:460-461.
  8. Fish R. Electric injury, part III: cardiac monitoring indications, the pregnant patient, and lightning. J Emerg Med. 2000; 18(2):181-7.

 

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