- Accidental hypothermia is the result of an unanticipated environmental exposure to cold temperatures. It is manifested as a core temperature of <35°C (95°F).
- May take several hours to days to develop
- While patients with cold-water immersion may appear dead, they can sometimes still be resuscitated.
- System(s) affected: all body systems
- Synonym(s): accidental hypothermia
- Predominant age: very young and the elderly
- Predominant sex: male > female
More common in elderly due to lower metabolic rate, impaired ability to maintain normal body temperature, and impaired ability to detect temperature changes
From 1999 to 2011, the CDC reported 16,911 deaths due to hypothermia.
Estimates vary widely; typically a secondary issue
Etiology and Pathophysiology
Core temperature is typically tightly maintained between 36.5°C and 37.5°C. Accidental hypothermia is most often the result of overwhelming environmental cold stress. Other contributing factors include:
- Decreased heat production (e.g., hypopituitarism; hypothyroidism; adrenal insufficiency)
- Increased heat loss (e.g., immersion—this is the most commonly encountered form of hypothermia in emergency situations—or burns)
- Alcohol consumption (found to contribute in up to 68% of cases)
- Impaired thermoregulation (e.g., stroke, CNS tumors)
- Children, especially young children and infants, are at greater risk for hypothermia than adults because younger children have a larger ratio of surface area to body mass.
- Young infants cannot increase heat production through shivering. Children and infants have limited glycogen stores to maintain heat production.
- Children and infants have a decreased ability to recognize, avoid, or escape hypothermic exposure. Also, the history may not suggest hypothermia. Hypothermia does not require extreme exposure in children. Nonaccidental trauma may be also be contributory.
- Alcohol consumption; drug intoxication
- Cardiovascular disease; cardiac arrest
- Cold-water immersion; prolonged environmental exposure
- Dermal dysfunction (burns, erythrodermas)
- Endocrinopathies (myxedema, severe hypoglycemia)
- Excessive fluid loss
- Hepatic failure; renal failure/uremia; sepsis
- Hypothalamic and central nervous system (CNS) dysfunction
- Mental illness; Alzheimer disease
- Trauma (especially head)
- Appropriate clothing, with particular attention to head, feet, and hands
- For outdoor activities, carry survival bags with rescue foil blanket for use if stranded or injured.
- Avoid alcohol.
- Remain alert to early symptoms and initiate preventive steps (e.g., drinking warm fluids; getting out of the cold).
- Identify medications that may predispose to hypothermia (e.g., neuroleptics, sedatives, hypnotics, tranquilizers).
Commonly Associated Conditions
- Addison disease; hypothyroidism; hypopituitarism; diabetes; ketoacidosis
- CNS dysfunction
- Congestive heart failure
- Pulmonary infection; sepsis
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