Hypothermia

Man has a complex, physiologically coordinated system designed to maintain a core temperature of 37 deg C. Despite the amazing capacity and responsiveness of the thermoregulatory system, human health is frequently challenged by cold stress leading to hypothermia. Recently, unpredictable climatic conditions were responsible for the deaths of five mountaineers on Mount McKinley. The incidence of hypothermia is not limited to cold latitudes. Hypothermia may occur in even tropical regions. Add to this the many cases of cold water exposure and hypothermia secondary to trauma, and it is clear that accidental hypothermia due to environmental cold conditions is a very real concern for clinicians. External factors, however, are not the only causes of hypothermia. Indeed, hypothermia is frequently the result of anesthesia or drugs that interfere with internal thermoregulatory mechanisms. Annually, between one and seven million patients in postanesthetic care units experience mild hypothermia. The expense and threat to human health, especially in patients with compromised conditions associated with cardiovascular, endocrine, and degenerative disorders, is just beginning to be recognized and evaluated. This review will focus on the current understanding of human thermoregulation, the common basis for understanding various categories of hypothermia, and therapeutic approaches to its management and treatment.