Hypothermia (Extended Exposure to Cold) (cont.)

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What body parts are more susceptible to hypothermia?

The body parts most susceptible to injury in patients with hypothermia are those that may suffer from poor circulation or often have the least protection from the cold environment (feet, hands, nose and ears, for example). These extremities usually cool faster than the body's core. The internal organ most susceptible to hypothermia is the heart (dysrhythmias).

What causes hypothermia?

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The cause of hypothermia is the inability of the body's temperature regulation system to keep the body's core temperature between 35.6 C and 37.5 C (96.08 F and 99.5 F). The body regulates the core temperature by either generating heat, by cooling, or by heat conservation. Heat conservation can be accomplished by peripheral vasoconstriction and by behavior; heat production is done by shivering and by increasing levels of thyroxine and epinephrine.

What are the signs and symptoms of hypothermia?

The signs and symptoms of hypothermia vary depending upon how severe the hypothermia becomes. In general, there is a sequence of symptoms:

  • In mild hypothermia, the person will shiver and their heart rate, breathing rate, and blood pressure will increase.
  • As the core temperature drops further, below 95 F (35 C), the pulse and breathing rates drop as does the blood pressure.
  • The person may experience apathy, confusion, slurred speech, and an inability to perform simple tasks.
  • As the core temperature drops further (below about 89.9 F or 32.16 C), shivering stops, the appears appears to be semi-comatose, and the heart rhythm may become irregular.
  • Below 82.4 F or 28 C, the person has no reflexes, and the heart's output capacity falls.
  • The person's pupils become dilated and the patient appears comatose or dead.

These signs and symptoms can appear rapidly (minutes) in individuals immersed in very cold water. They may appear more gradually (over several hours) in people that develop hypothermia without water immersion, but with exposure to cold environments. Some people will develop other signs of cold weather induced hypothermia by having extremities (hands or feet) show cold related damage such as frostbite. These symptoms can appear in men, women, and children.

Picture of the Stages of Frostbite
Picture of the Stages of Frostbite
Medically Reviewed by a Doctor on 2/27/2014

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