Published on 14/03/2015 by admin
Filed under Emergency Medicine
Last modified 14/03/2015
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9
Although the chances of being struck by lightning are minimal, 200 to 400 persons are victims of lightning strikes in the United States each year, resulting in an average of 51 deaths per year. Worldwide estimates are up to 240,000 annual injuries with up to 24,000 deaths. Lightning is the electrical discharge associated with thunderstorms. An initial electrical stroke can show a potential difference between the tip and the earth that ranges from 10 to 200 (average 30) million volts. Up to 30 strokes that constitute a single lightning flash give lightning its flickering quality. The main stroke usually measures 2 to 3 cm in diameter, and its temperature at the hottest has been estimated to range from 8000° to 50,000° C (14,432° to 90,032° F), or up to four times as hot as the surface of the sun. Thunder results from the shock waves generated by the nearly explosive expansion of the heated and ionized air. Thunder is seldom heard over distances greater than 10 miles (16 km).
Lightning can cause injury by (1) direct hit, (2) splash as the bolt first hits an object and then jumps to the victim, (3) contact with a conductive material that is hit or splashed by lightning, (4) step voltage where the bolt hits the ground or a nearby object and then flows like a wave in a pond to the victim, (5) ground current, (6) surface arcing, (7) upward streamer current, or (8) blunt trauma from the explosive force of the positive and negative pressure waves (thunder) it produces. The “flashover phenomenon” describes the situation wherein the electrical current of lightning travels appreciably over the body’s surface, rather than through it. This likely accounts for vaporized moisture on the skin and unique skin burn patterns.
Box 9-1 lists the types of immediate injuries that can occur with any of the effects of lightning, which is best described as a unidirectional massive current impulse.
Box 9-1 Types of Immediate Injuries Attributable to Lightning
1. Cardiopulmonary arrest
a. Immediate cardiac arrest that may be brief because of inherent automaticity
b. Respiratory arrest, caused by paralysis of the medullary respiratory center, which leads to secondary cardiac arrest from hypoxia
2. Neurologic injury
a. Seizures
b. Deafness
c. Confusion or amnesia
d. Blindness
e. Dizziness
f. Extremity paralysis
g. Headache, nausea, and postconcussion syndrome
3. Contusions and fractures
4. Chest pain and muscle aches
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