Difference between revisions of "Electrical injuries"

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===DC vs AC===
 
===DC vs AC===
 
Direct current (DC) injuries typically due to [[lightning]] while alternating current (AC) are household injuries
 
Direct current (DC) injuries typically due to [[lightning]] while alternating current (AC) are household injuries
 +
 +
====DC====
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*Direct current most often demonstrates flow-over phenomenon
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*Lightening can reach 1-5 million volts, but current flows over the body and exits to the ground
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*May result in little tissue damage and [[cardiac dysrrhythmias]] are still of great concern
  
 
====AC====
 
====AC====
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*With alternative cycle of the current there is contraction and release of muscle preventing full release from source
 
*With alternative cycle of the current there is contraction and release of muscle preventing full release from source
 
*Current flows through body tissues
 
*Current flows through body tissues
 
====DC====
 
*Direct current most often demonstrates flow-over phenomenon
 
*Lightening can reach 1-5 million volts, but current flows over the body and exits to the ground
 
*May result in little tissue damage and [[cardiac dysrrhythmias]] are still of great concern
 
  
 
==Clinical Features==
 
==Clinical Features==
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==Disposition==
 
==Disposition==
 
*Discharge
 
*Discharge
**Asymptomatic pts w/ normal ECG on presentation after a <600V injury
+
**Asymptomatic pts w/ normal ECG on presentation after a low-voltage electrical injury
 
*Admit
 
*Admit
 
**All pts with high-voltage injuries (even if asymptomatic)
 
**All pts with high-voltage injuries (even if asymptomatic)
**Pts w/ low-voltage injury if symptomatic (e.g. chest pain, burns, abnl EKG, ↑ CK)
+
**Pts w/ low-voltage injury if symptomatic (e.g. LOC, severe burns, EKG changes, ↑ CK)
  
 
==See Also==
 
==See Also==

Revision as of 09:05, 12 July 2015

Background

  • Tissue damage occurs via electrical energy (becomes thermal energy once it enters the body) and mechanical injury from trauma
    • Skin, bone, tendon all have very high resistance
    • Muscle, nerves, vasculature have lower resistance, more often damaged
  • The primary determinant of injury is the amount of current flowing through the body, which depends on:
    • Voltage
    • Amperage
    • Resistance
    • Type of current (DC or AC)
    • Current pathway
    • Duration of contact

Electrical Injury Types

  1. Low-Voltage <1000V
  2. High-Voltage >1000V - typically seen in industrial settings or transmission line injuries
    • Associated with electrical burns
  3. Lightning Strike
  4. Electric Arc
    • Associated with high voltage sources
    • Ionized particles with temp 3000 °C–20,000 C[1]
    • Can jump 2-3cm per 1000V[1]
    • May radiate enough heat to burn persons 10ft or more away from the arc
    • Blast force may result in trauma

DC vs AC

Direct current (DC) injuries typically due to lightning while alternating current (AC) are household injuries

DC

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

AC

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

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
    • Most common dysrrhythmia at presentation is A-fib (V-fib is more common, but pts are dead PTA)
    • Asymptomatic pts w/ normal ECGs do not develop later dysrhythmias after <1000V injuries

Cardiovascular Injury

  1. Contraction band necrosis[2]
  2. Medial necrosis of large vessels
    • Aneurysm formation
  3. Coagulation necrosis of small vessels

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)
    • May occur with voltages as low as 120V
  2. Compartment Syndrome
    • Usually a/w high-voltage injuries
    • May occur even with 120V shocks if contact is sustained for longer than few seconds
    • Pt experiences ongoing muscle pain with movement
    • Need for fasciotomy predicted by:
      • Myoglobinuria
      • Burns >20% BSA
      • Full-thickness burn >12% BSA
  3. Rhabdomyolysis

Ocular Injury

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

Auditory Injury

  • May be damaged by current or hemorrhage
  • Check hearing in all pts

Cutaneous Burns

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

GI Injury

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

Workup

  • 12-lead EKG
  • CBC
  • CMP
  • Lactate
  • Troponin
  • CK
  • UA and urine myoglobin

Treatment

  • Usual trauma evaluation and resuscitation applies
  • Use Parkland formula as starting point for fluid resuscitation
    • 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
  • Treat rhabdo and compartment syndrome in usual manner
    • If RBCs and/or myoglobin in UA, urine should be alkalinized at minimum of 2 cc/kg/hr until pigments eliminated[3]
    • Mannitol should be given early to prevent renal tubular damage
    • High voltage injuries to the hand frequently require carpal tunnel decompression as soon as pt is stable for OR

Disposition

  • Discharge
    • Asymptomatic pts w/ normal ECG on presentation after a low-voltage electrical injury
  • Admit
    • All pts with high-voltage injuries (even if asymptomatic)
    • Pts w/ low-voltage injury if symptomatic (e.g. LOC, severe burns, EKG changes, ↑ CK)

See Also

References

  1. 1.0 1.1 Kym D, Seo DK, Hur GY, Lee JW. Epidemiology of electrical injury: Differences between low- and high-voltage electrical injuries during a 7-year study period in South Korea. Scand J Surg. 2015 Jun;104(2):108-14.
  2. Koumbourlis AC. Electrical injuries. Crit Care Med. 2002 Nov;30(11 Suppl):S424-30.
  3. Brandt CP, Yowler CJ, Fratianne RB. MetroHealth Medical Center Burn ICU Handbook (Not a policy manual), Cleveland, OH.