Immersion injury is a peripheral nonfreezing cold injury resulting from exposure to water, usually at temperatures just above freezing. However, the condition can occur during prolonged exposure to any cold wet environment. Dependency and immobility predispose to immersion injury. The degree of injury depends on exposure time and temperature. The first symptoms usually appear within hours. Tissue loss may occur after many days of exposure, but is more likely due to tissue necrosis or compartment syndrome due to swelling inside boots than to immersion injury. Prior to rewarming, the distal extremities are numb and swollen. The skin is first red, then changes to pale, mottled, or black. Cramping of the calves may occur. Immersion injury is distinct from tropical immersion foot or warm-water immersion foot as seen in the Vietnam War. Tropical immersion foot was typically seen after 3 to 7 days of exposure to water at 22°C to 32°C. Warm-water immersion foot was seen after 1 to 3 days at 15°C to 32°C. These syndromes were characterized by burning in the feet, pain on walking, pitting edema, and erythema, with wrinkling and hyperhydration of the skin. They resolved completely after rest and removal from the wet environment.
Immersion Injury. Immersion injury of the hands (an unusual location) several hours after rewarming. The patient spent 18 hours bailing out a boat in waters just above freezing in Alaska. (Photo contributor: Ken Zafren, MD.)
Immersion Foot. Early appearance of immersion foot in a mentally ill homeless patient. (Photo contributor: Ken Zafren, MD.)
Management and Disposition
Hypovolemia, hypothermia, and associated injuries are the rule and should be treated first. Extremities with immersion injuries should be allowed to rewarm gradually at room temperature with bed rest, elevation, and air drying unless frostbite that has not yet thawed is present. Extremities that are frozen require rapid rewarming in warm water. Swelling of immersion injuries may produce compartment syndrome and require fasciotomy. Most patients require admission to the hospital.
Severe Trench Foot. This unfortunate homeless patient suffered prolonged exposure to a cold wet environment with resulting severe trench foot. (Photo contributor: Alan B. Storrow, MD.)
Doppler ultrasound may be useful to identify peripheral pulses, as pulses are often difficult to palpate in affected extremities.
Mixed injuries (frostbite and immersion) are possible.