Long William B, Edlich Richard F, Winters Kathryne L, Britt L D
Trauma Specialists LLP, Legacy Emanuel Hospital, Portland, Oregon 97227, USA.
J Long Term Eff Med Implants. 2005;15(1):67-78. doi: 10.1615/jlongtermeffmedimplants.v15.i1.80.
Exposure to cold can produce a variety of injuries that occur as a result of man's inability to adapt to cold. These injuries can be divided into localized injury to a body part, systemic hypothermia, or a combination of both. Body temperature may fall as a result of heat loss by radiation, evaporation, conduction, and convection. Hypothermia or systemic cold injury occurs when the core body temperature has decreased to 35 degrees C (95 degrees F) or less. The causes of hypothermia are either primary or secondary. Primary, or accidental, hypothermia occurs in healthy individuals inadequately clothed and exposed to severe cooling. In secondary hypothermia, another illness predisposes the individual to accidental hypothermia. Hypothermia affects multiple organs with symptoms of hypothermia that vary according to the severity of cold injury. The diagnosis of hypothermia is easy if the patient is a mountaineer who is stranded in cold weather. However, it may be more difficult in an elderly patient who has been exposed to a cold environment. In either case, the rectal temperature should be checked with a low-reading thermometer. The general principals of prehospital management are to (1) prevent further heat loss, (2) rewarm the body core temperature in advance of the shell, and (3) avoid precipitating ventricular fibrillation. There are two general techniques of rewarming--passive and active. The mechanisms of peripheral cold injury can be divided into phenomena that affect cells and extracellular fluids (direct effects) and those that disrupt the function of the organized tissue and the integrity of the circulation (indirect effects). Generally, no serious damage is seen until tissue freezing occurs. The mildest form of peripheral cold injury is frostnip. Chilblains represent a more severe form of cold injury than frostnip and occur after exposure to nonfreezing temperatures and damp conditions. Immersion (trench) foot, a disease of the sympathetic nerves and blood vessels in the feet, is observed in shipwreck survivors or in soldiers whose feet have been wet, but not freezing, for long periods. Patients with frostbite frequently present with multisystem injuries (e.g., systemic hypothermia, blunt trauma, substance abuse). The freezing of the corneas has been reported to occur in individuals who keep their eyes open in high wind-chill situations without protective goggles (e.g., snowmobilers, cross-country skiers).
暴露于寒冷环境会导致多种损伤，这些损伤是由于人体无法适应寒冷所致。这些损伤可分为身体局部部位的损伤、全身性体温过低或两者兼而有之。体温可能因辐射、蒸发、传导和对流导致的热量散失而下降。当核心体温降至35摄氏度（95华氏度）或更低时，就会发生体温过低或全身性冷损伤。体温过低的原因有原发性和继发性之分。原发性或意外性体温过低发生在衣物不足且暴露于严寒环境的健康个体身上。继发性体温过低则是指另一种疾病使个体易发生意外性体温过低。体温过低会影响多个器官，其症状会因冷损伤的严重程度而异。如果患者是被困在寒冷天气中的登山者，体温过低的诊断很容易。然而，对于暴露于寒冷环境的老年患者，诊断可能会更困难。在任何一种情况下，都应使用低读数温度计检查直肠温度。院前处理的一般原则是：（1）防止进一步的热量散失；（2）先使身体核心温度复温，再使体表温度复温；（3）避免引发心室颤动。复温有两种一般技术——被动复温和主动复温。周围性冷损伤的机制可分为影响细胞和细胞外液的现象（直接效应）以及破坏有组织的组织功能和循环完整性的现象（间接效应）。一般来说，在组织冻结发生之前不会出现严重损伤。周围性冷损伤最轻微的形式是冻疮。冻疮比冻疮更严重，发生在暴露于非冻结温度和潮湿环境之后。浸渍足（战壕足）是一种脚部交感神经和血管的疾病，见于海难幸存者或脚部长期潮湿但未冻结的士兵。冻伤患者常伴有多系统损伤（如全身性体温过低、钝性创伤、药物滥用）。据报道，在风寒指数高的情况下不戴护目镜睁眼的个体（如雪地摩托驾驶者、越野滑雪者）会发生角膜冻结。
