Hypothermia

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What is hypothermia?

Hypothermia is defined as a body temperature (core, or internal body temperature) of less than about 95 F (35 C). Usually, hypothermia occurs when the body's temperature regulation is overwhelmed by a cold environment. However, in the medical and lay literature there are essentially two major classifications, accidental hypothermia and intentional hypothermia.

Accidental hypothermia usually occurs from an exposure to cold that results in lowering the body temperature.

Intentional hypothermia is body temperature lowering induced usually for a medical procedure.

This article will focus on accidental hypothermia. Hypothermia is a medical emergency that, when quickly and appropriately treated, people can recover with little or no consequences.

Body temperature, when discussing hypothermia, is usually termed "core" temperature. This temperature is the temperature measured inside the body. It's a measurement that is most accurately done by a rectal thermometer, a rectal probe thermometer that has a constant temperature readout or by a bladder or esophageal temperature device. Temperatures taken by other methods may not adequately measure core temperature.

What are the risk factors for hypothermia?

The highest risk factor for hypothermia is losing body heat due to exposure to cold weather or partial or complete immersion in cold water. Examples of include:

  • Not dressing appropriately for cold weather
  • Walking on a partially frozen body of water (rivers, lakes, ponds, etc.)

Other risk factors for hypothermia include:

  • The young and elderly because their bodies do not have the ability to regulate body temperature efficiently
  • People with mental illness
  • People with alcohol or drug problems
  • Some medications

Some medical diseases or conditions may decrease the body's ability to regulate its internal temperature, for example:

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). 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), so any body temperature below about 35.6 C (96.08 F) is considered hypothermic by many doctors.

The body regulates the core temperature by either:

  • generating heat
  • cooling, or
  • 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.
Medically Reviewed by a Doctor on 12/16/2014

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Hypothermia Symptoms

Symptoms of hypothermia include:

  • Shivering
  • Slow breathing
  • Drowsiness
  • Mood changes
  • Irritability
  • Poor coordination
  • Confusion
  • Slurred speech