Wilderness and Rescue Medicine 7th Edition Jeffrey Isaac, PA-C and David E. Johnson, MD

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Wilderness and Rescue Medicine

Side flash occurs when a tall tree or structure is struck and some of the current arcs onto other nearby objects on its path to ground. This explains why seeking shelter near a tall object is not neces- sarily safe. Side flash causes 30–35% of lightning fatalities. The term touch voltage describes contact with lightning current through an object like a wire fence or mast shroud and contributes to 15–20% of lightning fatalities. The remaining 10–15% of deaths are caused by contact with an upward streamer. The extent of injury from current is related to the path the current takes over and through the body. If you are holding onto the mast of your sail- boat when the masthead is struck, the current may pass through your arm and chest and out your feet. The vital organs of the critical body systems can become part of the path, producing serious criti- cal system problems. If you are standing, ground current usually passes into one foot and out the other, leaving the vital organs outside the path. Scene Safety In responding to a lightning injury, the scene size-up for dangers is particularly important. If the storm continues, it may be very dangerous to approach the scene on a hilltop or cliff face. Look for more than one patient; about 10% of lightning injuries involve two or more people.

General Principles

Lightning Exposure

• Direct strike • Ground current • Side flash • Streamer effect • Touch Voltage

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The direct current flow in a lightning strike can disrupt the electrochemical function of the nervous system, causing respiratory and cardiac arrest. The current flowing over the skin heats the moisture on the surface, causing superficial burns and, in some cases, enough explosive force to blow clothing apart.

This rash, called Lichtenberg flowers, or ferning, is caused by lightning current passing through the dermis. The rash faded within hours. A direct hit where the patient becomes part of the main path to ground is likely to be the most devastating but accounts for only 3–5% of lightning deaths because it is so rare. A person is more likely to be injured or killed by ground cur- rent that spreads out through the earth, rock, or water from the point of contact with the lightning column. It can follow underground roots, pipes, wires, and water courses. Because the energy is diffused, this form of indirect exposure is gener- ally less devastating than a direct hit, but much more common. Ground current accounts for 50–55% of lightning fatalities.

General Principles

Scene Size-up: • Scene is unsafe if storm continues. • Multiple victims are likely. Mechanisms: • Concussive force • Shrapnel and splinters • Electrical injury Lightning Injuries 2 *

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Although it is rare, the explosive force in a direct strike or near miss can cause significant blunt trauma, including ruptured organs and broken bones. Burns caused by lightning are generally