Frostbite is injury from tissue freezing and formation of ice crystals in the tissue. Most tissue destruction follows reperfusion of the frozen tissues, with damaged endothelial cells and progressive microvascular thrombosis resulting in further tissue damage. In mild cases, only the skin and subcutaneous tissues are involved. Symptoms include numbness, prickling, itching, and pallor (eFigure 37–1). With increasing severity, deeper structures become involved. The skin appears white or yellow, loses elasticity, and becomes immobile. Edema, hemorrhagic blisters, necrosis, gangrene, paresthesias, and stiffness may occur (eFigure 37–2).
Digital ischemic lesions without necrotic tissue suggestive of superficial frostbite within all of the toes. (Used, with permission, from Dean SM, Satiani B, Abraham WT. Color Atlas and Synopsis of Vascular Diseases. McGraw-Hill, 2014.)
Deep frostbite, with the first and second toes showing an ischemic eschar with well-demarcated borders and clearcut margins, and hemorrhagic bullae on the second toe, the third toe showing a clear bulla and surrounding erythema, and the fourth toe showing complete necrosis. (Used, with permission, from Dean SM, Satiani B, Abraham WT. Color Atlas and Synopsis of Vascular Diseases. McGraw-Hill, 2014.)
Evaluate and treat the patient for associated systemic hypothermia, concurrent conditions, and injury. Early use of systemic analgesics is recommended for nonfrozen injuries. Fluids and electrolytes must be monitored. Hydrate patients orally or parenterally to avoid hypovolemia and to improve perfusion.
Rapid rewarming at temperatures slightly above normal body temperature may significantly decrease tissue necrosis and reverse the tissue crystallization. If there is any possibility of refreezing, the frostbitten part must not be thawed. Refreezing results in increased tissue necrosis. Ideally, the frozen extremity must not be used, but if required for evacuation, the affected frozen extremity must be padded and splinted to avoid additional injury. Rewarming is best accomplished by warm bath immersion. The frozen extremity is immersed for several minutes in a moving water bath heated to 40–42°C until the distal tip of the part being thawed flushes. In the absence of a thermometer, the temperature may be checked by an unaffected extremity, ideally of a caregiver rather than the patient. Water in this temperature range feels warm but not hot to the normal hand or wrist. If warm water is not available, then passive thawing in a warm environment must be allowed. Dry heat (ie, stove or open fire) is not recommended because it is more difficult to regulate and increases the likelihood of accidental burns. Thawing may cause tenderness and burning pain. Once the frozen part has thawed and returned to normal temperature (usually in about 30 minutes), discontinue external heat. In the early stage, rewarming by exercise, ...