TAILIEUCHUNG - Chapter 020. Hypothermia and Frostbite

Causes Primary accidental hypothermia is geographically and seasonally pervasive. Although most cases occur in the winter months and in colder climates, it is surprisingly common in warmer regions as well. Multiple variables make individuals at the extremes of age, the elderly and neonates, particularly vulnerable to hypothermia (Table 20-1). | Chapter 020. Hypothermia and Frostbite Causes Primary accidental hypothermia is geographically and seasonally pervasive. Although most cases occur in the winter months and in colder climates it is surprisingly common in warmer regions as well. Multiple variables make individuals at the extremes of age the elderly and neonates particularly vulnerable to hypothermia Table 20-1 . The elderly have diminished thermal perception and are more susceptible to immobility malnutrition and systemic illnesses that interfere with heat generation or conservation. Dementia psychiatric illness and socioeconomic factors often compound these problems by impeding adequate measures to prevent hypothermia. Neonates have high rates of heat loss because of their increased surface-to-mass ratio and their lack of effective shivering and adaptive behavioral responses. In addition malnutrition can contribute to heat loss because of diminished subcutaneous fat and because of depleted energy stores used for thermogenesis. Table 20-1 Risk Factors for Hypothermia Individuals whose occupations or hobbies entail extensive exposure to cold weather are at increased risk for hypothermia. Military history is replete with hypothermic tragedies. Hunters sailors skiers and climbers also are at great risk of exposure whether it involves injury changes in weather or lack of preparedness. Ethanol causes vasodilatation which increases heat loss reduces thermogenesis and gluconeogenesis and may impair judgment or lead to obtundation. Phenothiazines barbiturates benzodiazepines cyclic antidepressants and many other medications reduce centrally mediated vasoconstriction. Up to 25 of patients admitted to an intensive care unit because of drug overdose are hypothermic. Anesthetics can block the shivering responses their effects are compounded when patients are not covered adequately in the operating or recovery rooms. Several types of endocrine dysfunction can lead to hypothermia. Hypothyroidism particularly when

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