Electrical Injuries

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Electrical Injuries

• Stephen Hunt

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Electrical Injury

• Epidemiology
• Mechanisms of injury
• Associated injuries
• Management
• Prognosis

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Epidemiology

• Account for 3 all burn-related injuries
• Estimated 3,000 annual admits to burn units
• 1/3 fatal - about 1,000 US deaths annually
• Bimodal distribution
• 1/3 children lt6 yrs (electric cords wall
  outlets)
• 2/3 miners, construction, electrical workers
• Common cause occupational deaths
• Lightning responsible for 300 injuries, 100
  deaths

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Physics Review

• I V/R (Ohms Law - current)
• Intensity expressed in amperes (A)
• DC - lightning, rails, autos, batteries
• AC - most power lines, buildings
• E IVT (Joules law - thermal energy)
• E I2RT

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Mechanisms of Injury

• Direct effect of electrical current
• Thermal burns (conversion I-gtE)
• Mechanical Trauma
• Post-trauma sequelae

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Direct effects of current

• I V/R
• In general, type extent of injury depends on
  current intensity (amps)
• Type of current (DC vs AC), current pathway, and
  duration of current also influence severity of
  injury
• As current generally not known, injuries often
  classified into high V ( gt 1,000V) vs low V
• Cardiac, neurologic and respiratory systems most
  susceptible to direct effects
• Skin is the resistor most effecting severity of
  injury
• Wet skin has lower R (1K ohm) vs. dry or thick
  skin (gt100K ohm), resulting in greater current
  flow

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Thermal (Burn) Injuries

• Heat (E) IVT I2RT
• Type extent of injury depends on current
  intensity (I)
• R varies significantly between tissues
• Tissues with high R (e.g., bone), generate more
  heat, resulting in osteonecrosis and deep tissue
  periosteal burns, esp surrounding long bones
• Skin also has high R, thus entry/exit wounds
• Decreasing R (e.g., wet skin) results in lower
  thermal injury, but higher current conductance
• Coagulation of muscle, fat, vessels (i.e., the
  Bovie)
• Duration of current exposure (T)
• DC typically shorter duration, because single
  muscle spasm causes victim to be thrown from the
  source

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Mechanical Trauma

• Trauma can result from fall or muscle contraction
• Classic example is shock wave of lightning
  causing blast injuries
• Even at low V, tetanic muscle contraction can
  result in bone fx
• Cord injury can result from severe muscle
  contraction, w/o any external signs of trauma
• Can result in vascular compromise
• Acute hypotension should always prompt search for
  thoracic or intra-abdominal bleeding

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Post-trauma sequelae

• Crush injury syndrome (rhabdomyolysis,
  myoglobinuria)
• Multi-organ ischemic injury 2o/2 vascular
  coagulation or dissection
• Hypovolemic shock 2o/2 massive 3rd spacing
• Iatrogenic injuries from acute resuscitation
• Abdominal compartment syndrome
• ARDS

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Associated Injuries I

• Respiratory System
• Suffocation 2o/2 tetanic muscle contractions
• Respiratory arrest 2o/2 direct injury to RCC
• Cardiovascular System
• Asystole (more likely if DC or high V)
• Arrhythmias (more likely AC) (15 pts)
• Ventricular fibrillation most common fatal
  arrhythmia
• Myocardial necrosis (thermal effect)
• Anoxic injury 2o/2 respiratory arrest
• Neurological System
• Direct effects include LOC, autonomic
  dysfunction, amnesia, temp paralysis
  (keraunoparalysis)
• Cord injury 2o/2 spine fx 2o/2 muscle
  contractions
• Peripheral motor/sensory losses (long-term
  sequelae)

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Associated Injuries II

• Skin (57 low V fatalities 96 high V
  fatalities)
• Superficial, partial or full thickness thermal
  burns
• Degree of external injury can underestimate
  internal injury vice-versa
• Muscle
• Necrosis 2o/2 severe contraction or thermal
  injury
• Compartment syndrome 2o/2 edema from deep injury
  3rd spacing
• Skeletal
• Osteonecrosis 2o/2 thermal injury
• Fx 2o/2 muscle contraction or blunt trauma

Wright, et al, J Foren Sci, 1980
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Associated Injuries III

• Renal
• Pigment-induced renal failure
• Hypovolemia 2o/2 3rd spacing can lead to prerenal
• GI
• Injury rare, most commonly Curlers ulcers
• HEENT
• Cataracts can develop up to 2 years after
• Hearing loss from 8th nerve injury
• Damage to any organ system 2o/2 blunt trauma
• Damage to any organ system 2o/2 vascular damage

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Associated Injuries
Koumbourlis, Crit Care Med 2002
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Lichtenberg Figures

• Rare pathognomonic flower-like branching skin
  lesions in persons struck by lightning
• Caused by flashover effect of non-penetrating
  current
• Rapidly fade, not typically serious

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Management I

• Standard ABCDEs of any major trauma
• Pulmonary
• Low threshold for intubation, as respiratory
  failure common
• Cardiac
• Serial monitoring if high V, abnormal ECG, LOC,
  respiratory arrest, or PMH of CV dysfunction
• Neuro
• C-spine and log-roll precautions CT head spine
  often warranted
• Thorough serial neurological exams, as vessel
  coagulation can result in late sequelae

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Management II

• Musculoskeletal
• Thorough evaluation for fractures
• Serial evaluations of limbs for compartment
  syndrome requiring emergent decompression
• Even in absence of compartment syndrome,
  persistent aciduria or myoglobinuria may require
  limb amputation
• Skin
• Early debridement and later reconstruction
• Antibiotic prophylaxis (controversial)
• Renal
• Fluid resuscitation key, as 3rd spacing common
  myoglobinuria 2o/2 rhabdomyolysis can cause ARF

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Management III

• GI
• Ulcer prophylaxis, as gastric ulcers (Curlings
  ulcers) can develop
• Ileus uncommon, but should prompt evaluation for
  other injury
• Serial evaluation of liver, pancreatic, renal
  function for traumatic/anoxic/ischemic injury
• Judicious management of fluid and electrolytes to
  avoid acidosis and compartment syndromes

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Prognosis

• Highly variable, depending on severity of both
  initial injury and subsequent complications
• High morbidity/mortality in patients with
  multisystem organ failure
• Advances in surgical interventions (early
  excision, fasciotomy, skin grafts, etc) have
  improved

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References

• DM Mozingo BA Pruitt. 1998. Electric Injury. in
  Fundamentals of Surgery, 1st ed, JE Niederhuber,
  pp 194-195.
• DS Pinto PF Clardy. 2007. Environmental
  electric injuries. Up-to-Date, accessed
  06/01/2007.
• TN Pham NS Gibran. 2007. Thermal Electrical
  Injuries. Surg Clin N Am 87185-206.
• AC Koumbourlis. 2002. Electrical Injuries. Crit
  Care Med 30S424-S430.
• C Spies RG Trohman. 2006. Electrocution
  Life-Threatening Electrical Injuries. Ann Intern
  Med 145531-537.