Electrical injuries

Electrical Injuries
Andy Steval 04/02/2015

Contents
 Pathophysiology
 Epidemiology
 Types of Electrical injury
 Organ effects
 Management in the ED
 Common pitfalls

Pathophysiology
Current (I)
Resistance (R)
Voltage (V)

 I = V/R (Ohm’s law)
 Extent of damaged based on:
 Voltage
 Current
 Resistance to tissues
 Duration of contact
 Type of current (AC or DC)
 Path of current flow
 Alternating current (AC) and Direct Current (DC)

 The Amperage at which the human body is able to
withdraw from an electrical stimulus
 Once this is surpassed:
 Tetany
 Respiratory arrest
 Ventricular fibrillation
 Occurs more readily at higher currents, and alternating
current (AC)
The ‘let go current’

Types of electrical injury
Low-voltage High-voltage Lightning strike
• <1000 volts
• Alternating current
• Prolonged contact
• Ventricular Fibrillation
• Tetanic contraction
• Superficial Burns
• Rhabdo unlikely
• >1000 volts
• AC or DC
• Brief Contact
• Asystole
• Tetanic Sometimes
• Deep Burns
• Rhabdo Likely
• Up to 2 billions volts
• Direct Current
• Several milliseconds
• Asystole
• No tetany
• Variable tissue
damage
• Rhabdo unlikely

Organ effects
CNS
Cardiac
Orthopaedic
Dermatological
Abdominal
Ocular
Auditory
Respiratory

Cardiac
 Incidence of arrhythmia ranging from 4–17%
 VF more common in low voltage DC shocks. Asystole
more common in High voltage events.
 Virtually any abnormality possible: Increased PR/QT,
Ectopics, St segment, bundle branch blocks, etc
 Also: Direct myocardial injury

Respiratory
 Respiratory arrest:
 Tetanic contractions of thoracic muscles
 Autonomic nerve dysfunction
 Blunt chest trauma

Neurological
 CNS damage: High voltage injuries
 Loss of consciousness, agitation, coma, seizures
 Spinal cord damage
 PNS damage: Low voltage injuries
 Parasthesiae, Brachial plexus injuries

Orthopaedic
 Direct thermal energy leading to coagulation necrosis
 Secondary rhabdomyolysis, compartment syndrome
 Osteonecrosis
 Secondary fractures/dislocations from tetany and falls

Dermatological
 Often have entry and exit burns
 Painless, grey to yellow depressed areas if full-
thickness
 May hide extensive underlying damage to tissue if
high-voltage injury

Others
 Abdominal: Stress (Curling) ulcer, abdominal
perforation
 Renal: AKI secondary to rhabdomyolysis
 Ocular: Delayed onset cataracts in 6% high voltage
injuries, higher in lightning strike
 Auditory: Perforated TM, cochlear damage, VIII CN
damage

Management in the ED
 Low voltage injuries <240 volts:
 Asymptomatic patients with a normal ECG on arrival
and no abnormal clinical findings on examination
can be discharged with advice
 No other investigations needed
 Not even cardiac monitoring
 Not even a urine dip
 Just go home please (with advice)

 Red flags in the history and exam for more serious
injury (if low voltage patient):
 chest pain, palpations
 loss of consciousness, altered mental status,
confusion, weakness
 dyspnea, abdominal pain, weakness, burn with
subcutaneous damage
 vascular compromise, or abnormal results on ECG

 Further investigations in red flag patients:
 Urinary and serum myoglobin
 CK
 FBCs, U&Es, LFTS, Lipase, Coag studies
 Imaging where appropriate
 Admit these patients

 Admit all high voltage (>600 volts) injuries
 These patients will likely need transfer to a burns
centre if not immediate life threatening injuries

 Cutaneous injuries:
 Basic burns treatment for cutaneous burns
 Liaison with burns centre for more extensive injury
 Tetanus Prophylaxis

 Injuries to extremities:
 Close monitoring for signs of compartment syndrome
 Elevation of limb and splinting
 Fracture and dislocation reduction

 Myoglobinuria
 Places patients in high risk of renal failure
 Treat with aggressive fluid resuscitation until urine is
clear and any acidosis is corrected
 Consider bicarbonate and mannitol

Special considerations
 Lightning strikes:
 Virtually anyone who is struck by lightning who does
not suffer immediate cardiac or respiratory arrest will
survive
 Therefore at the scene, patients who appear dead
should be treated first. Often young patients with a
good change of surviving CPR
 Multiple delayed injuries: Neurological demyelination,
cataracts – need careful follow up after discharge

Common Pitfalls
(Taken from Emergency Medicine Practice, electrical injuries review)1
 “Results from the patient’s eye examination were
normal when he presented to the ED after a
lightning injury last month. I don’t know why he’s
back now weeks later complaining of decreased
vision.”
 Delayed onset cataracts

Common Pitfalls
 “The patient’s shoulder appeared normal on
examination and an anteroposterior (AP) radio-
graph looked fine to me. I don’t know how I missed
a posterior dislocation.”
 Tetany causes posterior dislocations

Common Pitfalls
 “I saw this patient in the ED 3 months ago with a
minor electrical injury to her hand. I don’t know
why she’s back now complaining of diffuse pain,
swelling, and coolness of her entire forearm.”
 CRPS

Common Pitfalls
 “This patient who was struck by lightning
was slightly confused on arrival to the ED and
couldn’t remember what had happened to him. I
thought this was true of almost all people struck by
lightning and was nothing to be too concerned
about.”
 High risk for traumatic brain injury, should get a CT
head

Common Pitfalls
 “The patient was awake and alert when he came in,
talking up a storm. The burns on his face didn’t
seem to bother him at all. I don’t understand how
he ended up with a crash airway.”
 Same as burns patients, may have unseen swelling
which rapidly progresses

Common Pitfalls
 “When that lightning strike patient came in with
pulseless, blue legs I thought he must have thrown
a clot. I thought I was doing the right thing when I
started him on a heparin infusion. Now he has a
head bleed and needs neurosurgical intervention.”
 Keraunoparalysis. Transient symptoms as above after
lightning strike – usually spontaneously resolve after a
few hours

Common Pitfalls
 “I have read a lot about electrical injuries, and I
know how important fluid resuscitation is. I tried
fluid resuscitation for my patient with a lightning
strike injury, and he ended up with flash pulmonary
edema.”
 Myoglobinuria uncommon after lighting strikes.
Management largely supportive

Common Pitfalls
 “I took care of this 3–year-old girl 2 weeks ago
when she presented with an oral arc burn. She was
healing well. I don’t understand why she is back
now with severe bleeding.”
 Common after children bite into electrical cords.
Delayed bleeding can occur when eschar separates at
2 weeks and labial artery tears (5-10%)

References
 1.) Emergency Medicine Practice - Electrical injuries, a Review for the Emergency
Clinician. Oct 2009
 2.)Tintinalli’s Emergency Medicine
 3.) Leesa ‘The Squid’ Equid

Electrical injuries

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