Damage to the body tissues caused by exposure to extreme cold
Exposure to extreme cold can freeze the body tissues and damage them, a condition that is known as frostbite. If not treated, frostbite may result in tissue death and permanent damage to the affected area. Frostbite can develop at any temperature below 0°C (32°F). The lower the temperature, the more rapidly frostbite develops. The risk of frostbite is increased by windy conditions.
People who have impaired circulation, such as those with diabetic vascular disease, are at increased risk of frostbite. Certain drugs affecting circulation (see Beta-blocker drugs) may also make frostbite more likely.
The extremities are most susceptible to frostbite and are affected first. White, cold patches of skin appear, accompanied by tingling. These symptoms are followed by numbness. When warmed, mildly affected tissues become red and swollen. If frostbite is more severe, blisters appear, and the area becomes very painful. Prolonged frostbite may lead to tissue death (see Gangrene), and the skin may appear black or dark blue. Frostbite is often associated with hypothermia.
If you or someone with you develops frostbite, you should warm the affected areas only as long as there is no possibility of refreezing. Rewarming should be carried out slowly by immersing the affected areas in warm water that is not too hot to touch. Remove the affected areas from the water as they return to a normal colour. Do not rub frostbitten areas. You should not warm the skin with direct heat, such as a fire, because the skin may be burned before sensation returns. Place gauze between the frostbitten fingers and toes, and bandage the affected areas loosely.
If the affected area does not completely recover with warming, go to hospital as soon as possible. In hospital, rewarming will be completed, and sterile dressings applied to reduce the risk of infection. Physiotherapy may also be required to promote circulation to the affected areas. In very severe cases, and after all other means have been tried, amputation of dead areas may be necessary to preserve nearby healthy tissue.
Frostbite damage usually heals within 6 months, but lasting sensitivity to low temperatures is common. If frostbite is severe, stiffness, pain, and numbness may persist indefinitely.
Frostbite can be prevented by dressing warmly when going outside in very cold weather, paying particular attention to the extremities.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.