CHAPTER 139 Frostbite

Unlike other animals that live outside the tropics, humans are susceptible to peripheral cold injuries. The highest homeostatic priority is to maintain the body’s core temperature. This is accomplished through peripheral vasoconstriction and shunting, which prevent adequate heat distribution to the extremities. As a result, failure to achieve adequate protection from the environment results in injuries that are usually preventable. Peripheral cold injuries include both freezing and nonfreezing syndromes, which may occur independently or in conjunction with systemic hypothermia. Frostbite is the most common freezing injury. Trench foot and immersion foot are nonfreezing injuries that result from exposure to wet cold. Nonfreezing injury that usually occurs after exposure to dry cold is termed chilblains (pernio). The incidence and severity of frostbite correlate with predisposing factors as well as with the degree of cold stress. Most cases of civilian frostbite result from exposure to cold by individuals who have not given due consideration to risk factors for cold injury. Well-equipped ascents of the world’s highest peaks have been completed without cold injury when appropriate steps have been taken to address these factors. An increase in outdoor recreational activities has increased the number of people exposed to severe cold conditions. Unsheltered homeless people are no longer the most likely group at risk in areas with moderate climates. Military history is replete with accounts of the effects of cold injury on combat troops. Amputations and time lost to local cold injuries in both world wars and the Korean conflict were extensive. Trench foot was common among Argentine and British forces in the Falkland Islands. Napoleon’s Surgeon General, Baron Larrey, first recorded the disastrous effects of the freeze-thaw-refreeze cycle. During the 1812 to 1813 Russian invasion and retreat, soldiers would acutely thaw frozen extremities directly over open fires. The subsequent refreeze further increased tissue destruction. Unfortunately, the resultant gangrene was misattributed to this rapid thawing of frostbite and trench foot injuries. Therefore, gradual thawing, often including friction massage with snow, remained the standard treatment regimen until the 1950s. In 1961, Mills ultimately popularized rapid warm immersion rewarming after extensive experience with severe Alaskan frostbite cases. PRINCIPLES OF DISEASE