Electrical and Lightning Injuries

Published on 26/03/2015 by admin

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Last modified 26/03/2015

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Chapter 65 Electrical and Lightning Injuries

Amanda Pratt, MD

1 What characteristics of electrical energy predispose to severe injury?

In general, the higher the voltage and current, the worse the injury.

Alternating current (AC) causes intense muscle contractions, thus prolonging the exposure.

Direct current (DC) can cause significant trauma by throwing the victim from the source.

AC is three times more dangerous than DC of the same voltage.

2 Which body tissues offer the highest resistance?

From greatest to least resistance: bone > fat > tendon > skin > muscle > nerve. The most important resistor of current flow is skin, because it is typically the site of first contact. Dry skin over palms and soles can have a resistance of 100,000 ohms. When skin is wet, the resistance drops to 2500 ohms; when skin is immersed in water, resistance can be as low as 1500 ohms. Lowered resistance allows more current to penetrate deeper tissue.

Jain S, Bandi V: Electrical and lightning injuries. Crit Care Clin 5:319–331, 1999.

3 How does the pathway of the current through the body affect the degree of injury?

The path that a current takes determines the number of organs affected and thus the severity of injury. A vertical path parallel to the body involves almost all vital organs and is thus the most dangerous. A horizontal path from hand to hand spares the brain but can still be fatal because it can involve the heart, spinal cord, or respiratory muscles. A horizontal path through the lower body may cause severe local damage but is not typically fatal.

Koumbourlis AC: Electrical injuries. Crit Care Med 30:S424–S430, 2002.

4 Do electrical injuries cause significant external signs that provide a clue to the severity of injury?

No. Injury potential ranges from a superficial wound to multisystem failure. Deep injury may not be immediately apparent, particularly if the resistance of the skin has been lowered by moisture. Low-resistance structures sustain significant injury and necrosis that may not be apparent on initial physical examination.

Martinez JA, Nguyen T: Electrical injuries. South Med J 93:1165–1168, 2000.

5 What are the cardiac manifestations of electrical injuries?

Sinus tachycardia, premature ventricular contractions, reversible QT prolongation, and other arrhythmias have been reported.

Low-voltage AC may cause ventricular fibrillation.

High-voltage AC or DC is likely to cause ventricular asystole.

6 How may electrical injuries affect the respiratory system?

Primary central nervous system dysfunction at the respiratory center of the brain can induce apnea.

Paralysis or tetany of the respiratory muscles and diaphragm may occur.

7 How are the kidneys affected in electrical injuries?

Myoglobinuria with subsequent renal failure is possible; direct renal injury is rare.

8 Describe the neurologic effects of electrical injuries

Acute findings may include altered mental status, loss of consciousness, seizures, and paralysis.

Delayed findings (days to years) may include depression, memory loss, motor neuropathy, and transverse myelitis.

9 What are the dermatologic manifestations of electrical injuries?

Entrance and exit burns may be seen and should be evaluated to determine the path of current.

Burns across joints at the flexor creases on both flexor surfaces may be seen, known as “kissing burns.”

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