Out of the cold: management of hypothermia and frostbite

• Published in: Canadian Medical Association journal (CMAJ) 2003-02, Vol.168 (3), p.305-311
• Main Authors: Biem, Jay, Koehncke, Niels, Classen, Dale, Dosman, James
• Format: Article
• Language: English
• Subjects: Adaptation, Physiological; Aged; Combined Modality Therapy; Dehydration - prevention & control; Electrocardiography; Follow-Up Studies; Frostbite; Frostbite - diagnosis; Frostbite - therapy; Humans; Hypothermia; Hypothermia - diagnosis; Hypothermia - therapy; Male; Multiple Organ Failure - prevention & control; Practice; Resuscitation - methods; Rewarming - methods; Risk Assessment; Severity of Illness Index; Treatment Outcome
• ISSN: 0820-3946; 1488-2329

Although cold-induced injuries and hypothermia are usually accidental, they can result from social (e.g., homelessness, inadequate home heating,1-3 occupational,4-7 recreational,8-11iatrogenic12,13 and even criminal causes.14 It is difficult to obtain data on the incidence of cold-induced injuries and hypothermia. Hospital data are the "tip of the iceberg," representing only the most severe cases. According to Statistics Canada, there were 411 deaths from hypothermia, frostbite and other cold-induced injuries during 1992-1996.15 Several case series in western Canada of patients admitted to hospital with frostbite identified the main associated factors to be alcohol consumption, psychiatric illness, and motor vehicle accident or breakdown.16-18 Many underlying conditions increase a person's susceptibility to cold (Box 1). Infants have a high ratio of body surface area to mass, and elderly people have a decreased capacity for metabolic heat production and vasoconstriction.21 The amount of muscle and fat a person has may be more important than his or her age in defending against hypothermia.22 Less body fat decreases tissue insulation. Malnutrition and exertion decrease the fuel available for heat generation.23 Alcohol and sedative drugs dull mental awareness of cold and impair the judgement necessary to seek shelter or put on warm clothing. In addition, alcohol inhibits shivering, perhaps by causing hypoglycemia,24 and causes cutaneous vasodilatation, which counteracts the thermoregulatory response.25 The opioid meperidine and the alpha-adrenergic blocker clonidine also inhibit shivering.26 Neuroleptic drugs may predispose to hypothermia through antagonism of the serotonin receptor.27 Endocrine conditions such as hypothyroidism, adrenal insufficiency and hypoglycemia are accompanied by decreased metabolic heat production. People with diabetes mellitus may have peripheral or autonomic neuropathy. Peripheral neuropathy impairs the cold-induced nociception that might trigger retreat from cold. Both peripheral neuropathy and spinal cord damage may impair cutaneous vasoconstriction.28 Autonomic neuropathy impairs reflex peripheral vasoconstriction.29 Central nervous system degeneration, trauma or neoplasms may affect the hypothalamic thermoregulatory centre. Falls may be accompanied by hypothermia because of immobility and conductive heat loss.30 Hip fractures are more common during cold weather because of a greater risk of slipping or slower reaction times.31 In