Hypothermia risk factors in the elderly

Cold weather is especially risky for the elderly. Hypothermia is defined as the unintentional lowering of the core body temperature below 95 degree F or 35 degrees C. Hypothermia is a medical emergency that requires immediate attention. Exposure to excessively cold temperatures slow the actions of enzymes throughout the body. As a result, the individual who is hypothermic is at risk of potentially fatal coagulation disorders, renal failure, and cardiac dysrhythmias.

Approximately 600 elderly people die in the USA each year from hypothermia. Unfortunately, the prevalence of deaths from hypothermia tracks the cost of energy. Elderly people on a fixed income may cut back on heating during winter months if they feel they cannot afford heating bills.

A 2007 U.S. Department of Housing and Urban Development report to Congress revealed that 12.1% of sheltered homeless persons were 51 years or older between 2/05 and 4/05. The same age group represent 18.6% of the U.S. population living in poverty. While 51 years of age is not usually considered elderly, lack of medical care, poor nutrition and severe living conditions can reduce physical status to that of a 70 year old. Medical professionals need to identify any patient at risk from poor living conditions and engage social services.

There are a number of factors that make the elderly person especially prone to hypothermia. These factors include:

Increased heat loss. Hypothermia can occur when heat loss exceeds heat production. Subcutaneous fat acts to retain heat by insulating the muscle and organs from conductive heat loss. Diminished subcutaneous fat on the face and extremities increases the risk of hypothermia in the elderly. Persons in their 80's and 90's are at high risk for hypothermia when exposed to temperatures below 65 degrees Fahrenheit.

Decreased heat production may occur due to hypothyroidism, hypoglycemia, and starvation or malnutrition. Another common cause of decreased heat production in the elderly is decreased muscle activity due to immobility. Pain and depression can lead to reduced physical activity.

Vasodilation is a major risk factor for hypothermia in the elderly. Alcohol ingestion produces peripheral vasodilation, which increases heat loss. General anesthetics also cause vasodilation. OR nurses and anesthesiologists continuously monitor and control the patient's core temperature. Certain toxins released during sepsis can trigger vasodilation which may lead to hypothermia.

Drug-induced impairment: barbiturates, major or minor tranquilizers, tricyclic antidepressants are all known to have exaggerated effects in the elderly. These drugs can impair consciousness, dull sensations or cause the elderly to act inappropriately. Dulled sensations or failure to initiate protective actions can lead to hypothermic exposure.

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Elderly people have less subcutaneous fat and, as a result, are more prone to hypothermia than are younger people

Several websites discuss risk factors for hypothermia and hyperthermia in the elderly. Please review

U.S. Office of Consumer Affairs Special Report on Cold Stress (Hypothermia) and Heat Stress and

Morbidity & Mortality Weekly Report (requires Adobe Acrobat Reader)

MMWR 1/14/2000