frostbite [AS, frost + bitan] , a traumatic effect of extreme cold on skin and subcutaneous tissues that is first recognized by distinct pallor of exposed skin surfaces, particularly the nose, ears, fingers, and toes. Vasoconstriction and damage to blood vessels impair local circulation and cause anoxia, edema, vesiculation, and necrosis. Gentle warming is appropriate first-aid treatment; rubbing of the affected part is avoided. Later therapy is similar to treatment of thermal burns. Iatrogenic frostbite is the result of excessive use of ethyl chloride sprays for local anesthesia for the relief of muscle and tendon strains. Compare chilblain, immersion foot. ▪ OBSERVATIONS: Manifestations for superficial frostbite present as a white, waxy, soft, and numb appearance of the injured area while it is still cold. As thawing occurs, the area becomes flushed, edematous, and painful, and may become mottled and purple. Within 24 hours, large blisters form and remain for about 2 weeks before turning into a hardened eschar, which separates in about a month. As the eschar separates, it leaves painful, sensitive new skin that often sweats excessively. In deep frostbite, the injured part remains hard, cold, mottled, and blue-gray after thawing; edema forms in entire limb and may remain for months. Blisters may or may not form weeks after the injury. After several weeks, dead tissue blackens and sloughs off and a line demarcates dead from live tissue. Diagnosis is made by clinical evaluation plus a history of exposure to cold. Loss of digits, ears, nose, and extremities is possible, as is secondary infection and long-term residual symptoms, such as neuropathic pain, sensory deficits, hyperhidrosis, hair and nail deformities, and arthritis. ▪ INTERVENTIONS: Acute treatment centers around rapid rewarming by immersion in water (40° C to 42° C) for 15 to 30 minutes. Intravenous analgesics are used for pain. Immunological agents (tetanus) and antiinfective drugs are given for prophylaxis. Fluid and electrolytes are replaced. After the affected area has thawed, plasma expanders are used to reduce sludge and thrombus formation. Whirlpool hydrotherapy is used 20 to 30 minutes three to four times a day. Physical therapy is used to increase function after edema resolves. In deep and severe cases, escharotomy may be performed with debridement after retraction of viable tissue. Amputation is done for nonviable extremities. Sympathectomy may be performed for severe vasospasm. ▪ PATIENT CARE CONSIDERATIONS: Immediately after injury, constrictive and wet clothing should be removed and the affected area should be insulated and immobilized. The area should never be massaged or rubbed or subjected to dry heat. Associated hypothermia must be stabilized with heated saline; warming blankets; and warmed, humidified oxygen. Long-term precautions should be taken with injured area to prevent dislodgement of eschar and further damage. An exercise program may be needed to prevent joint restriction. Counseling may be needed for altered body image from loss of digits or limbs. Education is needed about adequate protection when exposed to cold temperatures and use of preventive measures, such as carrying extra clothing, coats, blankets, fluids, high carbohydrate foods, cell phone, and hazard markers in the car when traveling in cold weather.
