The sustained loss of body heat resulting in low body temperature. Hypothermia occurs with extended exposure to cold external temperatures. Cool, wet conditions may also result in hypothermia.

The key symptom of mild hypothermia, in which body temperature is no lower than 95ºF, is intense shivering. Attempt to warm the person getting him or her into a warm location, removing wet clothing and wrapping in warm blankets, and offering warm fluids to drink.

When body temperature drops below 95ºF in moderate hypothermia, the body loses the ability to shiver and the rate of heat loss increases. hearth rate slows, blood pressure drops, and metabolism slows.

The person is often confused or agitated, may paradoxically feel warm, and feels increasingly sleepy. Emergency response includes warming efforts as well as calling 911 to summon emergency aid personnel. Moderate hypothermia often requires further medical care to stabilize body temperature.

The lower body temperature drops, the less likely recovery becomes. Body temperature below 90ºF, severe hypothermia, is very precarious. Organ systems, especially the cardiovascular and neurologic, become exceedingly fragile.

How to survive hypothermia

The risk for life-threatening arrhythmia (irregular heart beat) and especially Ventricular fibrillation is already high because of the body’s altered metabolic and biochemical state; jostling the person during movement can rapidly destabilize the heart and cardiovascular function. Severe hypothermia significantly slows neurologic function, causing unconsciousness. The pupils are often fixed (nonresponsive to light).

Cardiopulmonary resuscitation (CPR) is necessary if the person is not breathing and has no pulse. As with cold water drowning, aggressive resuscitation efforts may revive someone who has had very low body temperature for an extended time.