Electrical injuries

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Background

  1. Tissue damage occurs via electrical energy, heat, and mechanical injury from trauma
    1. Skin, bone, tendon all have very high resistance
    2. Muscle, nerves, vasculature have lower resistance, more often damaged

Electrical Injury Types

  1. Low-Voltage
  2. High-Voltage (>1000V), seen in industrial settings or transmission line injuries
    • Associated with electrical burns
  3. Electric Arc
    • Associated with high voltage sources
    • May radiate enough heat to burn persons 10ft or more away from the arc
    • Blast force may result in trauma
  4. Pediatric Oral Burn
    • From biting an electric cord assoc w/ delayed labial bleeding (5d later) in ~10% of peds

DC vs AC

Usually direct current (DC) injuries are due to (lightening) while alternating current (AC) are household injuries

AC

  1. Current arcs onto body, envelops surface of body, then arcs to lower electromotive potential (ground)
  2. With alternative cycle of the current there is contraction and release of muscle preventing full release from source
  3. Current flows through body tissues

DC

  1. Direct current most often demonstrates flow-over phenomenon
  2. Lightening can reach 1-5 million volts, but current flows over the body and exits to the ground
  3. May result in little tissue damage and cardiac dysrrhythmias are still of great concern

The primary determinant of injury is the amount of current flowing through the body which depends on:

  1. Voltage
  2. Resistance
  3. Amperage
  4. Type of current
  5. Current pathway
  6. Duration of contact all influence the extent of injury.

Clinical Features

Immediate Effects

  1. Cardiac dysrhythmias
  2. Respiratory arrest
  3. Seizures

Cardiac Dysrhythmias

  1. Fatalities due to asystole or V-fib usually occur prior to arrival
    1. Most common dysrrhythmia at presentation is A-fib (V-fib is more common, but pts are dead PTA)
    2. Asymptomatic pts w/ normal ECGs do not develop later dysrhythmias after <1000V injuries

Cardiovascular Injury

  1. Contraction band necrosis[1]
  2. Medial necrosis of large vessels
    1. Aneurysm formation
  3. Coagulation necrosis of small vessels
    1. Can lead to compartment syndrome

CNS Injury

  1. Occurs in 50% of pts w/ high-voltage injuries
  2. Brain injury ranges from transient LOC to CVA to respiratory arrest
  3. High voltage injuries involving head are frequently associated with coma and persistent vegetative state

Orthopedic Injury

  1. Forceful muscle contractions can cause fracture and joint dislocations (especially shoulder)
    1. May occur with voltages as low as 120V
  2. Compartment Syndrome
    1. Usually a/w high-voltage injuries
    2. May occur even with 120V shocks if contact is sustained for longer than few seconds
    3. Pt experiences ongoing muscle pain with movement
    4. Need for fasciotomy predicted by:
      1. Myoglobinuria
      2. Burns >20% BSA
      3. Full-thickness burn >12% BSA
  3. Rhabdomyolysis
    1. Associated with:
      1. Contact with >1000V
      2. Prehospital cardiac arrest
      3. Crush injury
      4. Compartment syndrome
      5. Full-thickness skin burns

Ocular Injury

  1. Cataract formation has been described weeks to years after electrical injury
    1. Document presence or absence of cataracts following all electrical injuries

Auditory Injury

  1. May be damaged by current or hemorrhage
  2. Check hearing in all pts

Cutaneous Burns

  1. Often seen at electrical contact areas
    1. Seriously injured pts often have burns on either arm or skull + feet
  2. Most pts w/ burns from electrical injury require admission and care by burn specialist

GI Injury

  1. Suspect in pts with:
    1. Electrical burns of abdominal wall
    2. History of a fall, nearby explosion, or other mechanical trauma
  2. Labial artery bleeding may be delayed well after injury, warranting admission (peds pts who chew power cords)

Workup

  1. EKG, telemetry
  2. BMP, CBC
  3. Lactate
  4. Serial troponins, CK-MB
  5. LFTs
  6. CK
  7. UA, urine myoglobin

Treatment

  1. Usual trauma evaluation and resuscitation applies
  2. Use Parkland formula as starting point for fluid resuscitation
    1. Fluids in first 24 hrs = TBSA burned(%) x Wt(kg) x 4ml; Give 1/2 in first 8 hours, then give other 1/2 over next 16 hrs
  3. Treat rhabdo and compartment syndrome in usual manner
    1. If RBCs and/or myoglobin in UA, urine should be alkalinized at minimum of 2 cc/kg/hr until pigments eliminated[2]
    2. Mannitol should be given early to prevent renal tubular damage
    3. High voltage injuries to the hand frequently require carpal tunnel decompression as soon as pt is stable for OR

Disposition

  1. Discharge
    1. Asymptomatic pts w/ normal ECG on presentation after a <600V injury
  2. Admit
    1. All pts with high-voltage injuries (even if asymptomatic)
    2. Pts w/ low-voltage injury if symptomatic (e.g. chest pain, burns, abnl ECG, abnl CK)

See Also

Source

  1. Koumbourlis AC. Electrical injuries. Crit Care Med. 2002 Nov;30(11 Suppl):S424-30.
  2. Brandt CP, Yowler CJ, Fratianne RB. MetroHealth Medical Center Burn ICU Handbook (Not a policy manual), Cleveland, OH.