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7/28/2019 24364309 Electrical Injuries
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Stanford University Medical Center
22 April 2013
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
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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->E)
Mechanical Trauma
Post-trauma sequelae
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Direct effects of current
I = V/R
In general, type & extent of injury depends oncurrent 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 ( > 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 thickskin (>100K 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 moreheat, 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 lowerthermal 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 musclespasm 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 causingblast injuries
Even at low V, tetanic muscle contraction can resultin bone fx
Cord injury can result from severe musclecontraction, 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 vascularcoagulation 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 internalinjury & vice-versa
Muscle Necrosis 2o/2 severe contraction or thermal injury
Compartment syndrome 2o/2 edema from deepinjury & 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 & spineoften warranted
Thorough serial neurological exams, as vesselcoagulation 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 requirelimb 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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GI
Ulcer prophylaxis, as gastric ulcers (Curlingsulcers) can develop
Ileus uncommon, but should prompt evaluation forother injury
Serial evaluation of liver, pancreatic, & renal functionfor traumatic/anoxic/ischemic injury
Judicious management of fluid and electrolytes toavoid acidosis and compartment syndromes
Management III
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Prognosis
Highly variable, depending on severity of both
initial injury and subsequent complications
High morbidity/mortality in patients withmultisystem 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 Fundamentalsof 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 87:185-206. AC Koumbourlis.2002. Electrical Injuries. Crit Care Med
30:S424-S430.
C Spies & RG Trohman. 2006. Electrocution & Life-ThreateningElectrical Injuries.Ann Intern Med 145:531-537.