Hypothermia and Cold Weather Injuries.

Hypothermia, frostbite, and nonfreezing cold injuries predominantly affect older adults, homeless or intoxicated people, adventurers, and military personnel. Prevention begins with clothing that is clean, layered, and loose to promote circulation. Base layers made of moisture-wicking materials are favored over wool or cotton. Wool or fleece garments are ideal for middle layers, whereas outer layers should repel moisture. Hypothermia occurs when core body temperature drops below 95°F and can be staged by clinical symptoms when core temperature measurement is unavailable. Initial treatment includes external and internal rewarming. Warmed normal saline is favored over lactated Ringer solution. Frostbite is a freezing injury that usually affects the extremities. After rapid rewarming, prognosis is best determined with technetium 99mTc pyrophosphate scintigraphy or magnetic resonance angiography. Initial treatment includes protecting tissue from further trauma, preventing refreezing, and avoiding dry heat sources. Ideally, patients should be transported to facilities where rapid rewarming, imaging, and thrombolytic treatment are available. Tissue plasminogen activator significantly decreases amputation rates for severe injuries if started within 24 hours of rewarming. Immersion foot occurs during damp nonfreezing conditions. Rapid rewarming should be avoided, and amitriptyline should be considered for pain control.