ESSENTIALS OF DIAGNOSIS
“Keep warm, keep dry, and keep moving” to prevent cold-induced injury.
Rewarming of the extremity suffering cold-induced injury must be performed as soon as possible once there is no risk of refreezing; exercise, rubbing, or massage must be avoided during rewarming.
Cold exposure of the extremities produces immediate localized and then generalized vasoconstriction, which may result in a wide range of injuries. When the skin temperature falls to 25°C, tissue demand for oxygen is greater than what is supplied by the slowed circulation, producing peripheral cyanosis. At 15°C, tissue damage occurs due to marked reduction in tissue metabolism and oxyhemoglobin dissociation. This results in a deceptive pink, well-oxygenated appearance to the skin. Tissue damage occurs because of ischemia and intravascular thromboses, endothelial damage, or actual freezing. Freezing (frostbite) may occur when skin temperatures drop below –4°C to –10°C or during higher temperatures in the presence of wind, water, immobility, malnutrition, or vascular disease.
For all forms of cold-induced injury to an extremity, caution must be taken to avoid rubbing or massaging the injured area and to avoid applying moisture, ice, or heat. The cold-injured extremity must be protected from trauma, secondary infection, and further cold exposure.
“Keep warm, keep dry, and keep moving.” For optimal prevention of frostbite, individuals must wear warm, dry clothing, preferably several layers, with a windproof outer garment. Arms, legs, fingers, and toes must be exercised to maintain circulation. Wet clothing, socks, and shoes must be replaced with dry ones. Extra socks, mittens, and insoles must always be carried in a pack during travel in cold or icy areas. Risk factors include underlying diseases or medications that decrease tissue perfusion and prolonged cold environmental exposure. Caution must be taken to avoid cramped positions; wet or constrictive clothing; prolonged dependency of the feet; use of tobacco, alcohol, and sedative medications; and exposure to wet, muddy ground and windy conditions.