CHAPTER 4
COLD INJURY: IDENTIFICATION AND TREATMENT
4-1. Types of cold injuries
Cold injuries are classified into three categories: hypothermia, cold/dry (freezing), and cold/wet (nonfreezing). Hypothermia is defined as core body cooling below 95 °F. Cold/dry and cold/wet injuries are localized to extremities and exposed skin. Cold/dry injury causes freezing of cells and tissues and is known as frostbite. Cold/wet injury is classified as NFCI and includes chilblain and trench foot. It is not unusual for both hypothermia and local cold injuries to occur simultaneously. Figure 4-1 depicts the types of cold injuries and associated body temperatures.
4-2. Predisposing factors
a. The severity of hospitalized cold casualties has decreased dramatically in military personnel over the past several decades (see figure 4-2). Cold weather hospitalizations have declined from about 38 cases per 100,000 soldiers during the mid-1980's to 1 to 2 cases per 100,000 soldiers in 1998-1999, as more soldiers are treated on an outpatient basis. However, the number of total cases (hospital and outpatient) is still about 500 per year (figure 4-3). Clearly, cold/dry injuries are the most common, with hypothermia being relatively infrequent. However, the incidence of hypothermia cases could increase in operational settings where cold exposures are longer and resupply more difficult.
b. Figure 4-4 shows the number of cold-weather injury hospitalization cases per 100,000 person-years at each of the major Army installations from 1998 to 2003. This figure illustrates that although cold-weather injuries are most prevalent at northern bases, cold injury hospitalizations occur throughout the continental United States (including the South), Korea, and Germany.
Cold injuries by Army installation, 1998-2003.
c. Table 4-1 presents the predisposing factors for hypothermia. These factors can be broadly categorized into those that decrease heat production, those that increase heat loss, those that impair thermoregulation, and other miscellaneous clinical states. The latter category is vague because of the many mechanisms for disease that can interfere with thermoregulation and may be more applicable in local civilian populations than in deployed forces, since soldiers are not deployed if they have been diagnosed with a serious disease.
d. Mission factors