The occurrence of cold-related injuries depends on the degree of cold exposure, as well as environmental and individual factors. Frostbite is the prototypical freezing injury and is seen when ambient temperatures are well below freezing. Nonfreezing cold injuries occur as a result of exposure to wet conditions when temperatures are above freezing. The most common nonfreezing cold injuries are trench foot and chilblains. Although frostbite is likely to result in permanent tissue damage, nonfreezing cold injuries are characterized by usually mild but uncomfortable inflammatory lesions of the skin. This chapter describes the occurrence, risk factors, and treatment of the nonfreezing cold injuries—trench foot and immersion foot, chilblains or pernio, panniculitis, and cold urticaria—and freezing injury—frostbite.
NONFREEZING COLD INJURIES
Trench foot, or immersion foot, was first identified during military operations. Homelessness, alcoholism, substance abuse, and psychiatric disorders are risk factors for trench foot.1,2 The pathophysiology of trench foot is multifactorial, but involves direct injury to soft tissue and peripheral nerves sustained from prolonged cooling, accelerated by wet conditions.3
Early symptoms progress from subjective tingling to numbness of the affected tissues. On initial examination, the foot may appear pale, mottled, anesthetic, pulseless, and immobile, with no immediate change after rewarming. A hyperemic phase begins within hours after rewarming and is associated with severe burning pain and reappearance of proximal sensation. As perfusion returns to the foot over 2 to 3 days, edema and bullae may form. Anesthesia frequently persists for weeks and may be permanent. In more severe cases, tissue sloughing and gangrene may develop. Hyperhidrosis and cold sensitivity are common late features and may persist for months to years. Severe cases may be associated with prolonged convalescence and permanent disability.4 Treatment is supportive, but vasodilator drugs may be tried, such as oral prostaglandin E1, limaprost, a vasodilator that increases blood flow and inhibits platelet aggregation. Limaprost, 20 micrograms orally three times daily, has been shown to increase skin temperature, which suggests improved circulation.5 Feet should be kept clean and warm and be dryly bandaged, elevated, and closely monitored for early signs of infection. Prophylaxis for trench foot includes keeping warm, ensuring good boot fit, changing out of wet socks several times a day, never sleeping in wet socks and boots, and, once early symptoms are identified, maximizing efforts to warm, dry, and elevate the feet.
Chilblains, or pernio, are characterized by mild but uncomfortable inflammatory lesions of the skin caused by long-term intermittent exposure to damp, nonfreezing ambient temperatures. Symptoms are precipitated by acute exposure to cold.6 The most common areas affected are the feet (toes), hands, ears, and lower legs. Chilblains are primarily a disease of women and children, and although rare in the United States, the disease is common in the United ...