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AT-A-GLANCE

AT-A-GLANCE

  • Skin is important for maintaining core body temperature within a narrow physiologic range.

  • Cold weather, wind, humidity, dampness, and altitude combine to inflict skin damage.

  • Freezing and nonfreezing conditions can both produce cold injuries.

  • Frostbite occurs after exposure to intensely cold air, liquids, or metals. Several degrees of frostbite are recognized.

  • Self-inflicted freeze injuries from inhalant abuse and peer challenges are emerging.

  • Winter xerosis and acrocyanosis are common consequences of prolonged exposure to cold.

  • Pernio is an acral eruption of edematous violaceous papules occurring in cool rather than freezing exposures, and seen more frequently in lean persons.

  • Cold urticaria is rare and occurs at the sites of localized cooling.

  • Cold panniculitis typically occurs on legs and cheeks.

Many physiologic, behavioral, and environmental factors predispose to cold injuries. Marked increases in convective, conductive, or radiant heat loss are responsible for the immediate effects of cold exposure. A cold environment can be a threat to the skin, and can lead to subsequent fall in core body temperature. Cold injuries are becoming more prevalent among the general population.1 Outdoor work, winter sports, windy conditions, humidity, altitude, and skin contact with cold objects are environmental factors that may predispose an individual to cold damage.2 Insulation from clothing is insufficient when garments are too light, wet, tight, permeable to wind, or inadequate to cover the cold sensitive body parts. Frostbite prevails among winter sport enthusiasts, such as cross-country skiers and backpackers, who get lost or trapped in a snowstorm.3-8 Accidental exposure to liquefied gas is an emerging cause of severe cold injuries.9

The human capacity for physiologic adaptation to cold is minimal. This deficiency may cause problems because seasonal changes in the outdoor environment can be quite dramatic, even in the temperate zones of the world. Skin is important in thermoregulation. Cutaneous blood flow and the resulting skin temperature may vary widely to preserve the core body temperature.10,11 In fact, the body can maintain a constant core temperature of approximately 37°C (98.6°F) over a range of external temperatures between 15°C and 54°C (59°F and 129.2°F). In addition to external temperature, physiologic, behavioral, and environmental factors modulate skin responses to cold exposure.

THERMOREGULATION AND PHYSIOLOGIC RESPONSE TO COLD

Cutaneous thermoregulation is complex. As external temperature decreases, central thermoregulation centers in the hypothalamus signal other hypothalamic control centers to generate or conserve heat. Core body temperature is prioritized and maintained largely by controlling cutaneous blood flow. Arteriovenous anastomoses are abundant in acral areas, and they regulate the volume of blood passing through the skin. When the skin is cooled, there is usually an immediate vasoconstrictive response to reduce the amount of blood flowing at the skin surface. Without this vasoconstriction there would be significant heat transfer from the blood flowing in the skin to the environment, leading eventually to core temperature drop. The parallel arrangement of large arteries ...

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