HYPOTHERMIA

Hypothermia is potentially the most important wilderness danger the outdoor enthusiast is likely to encounter. It is a major cause of death among recreationalist. Hypothermia is the rapid, progressive mental and physical collapse accompanying the chilling of the inner core of the human body. It is caused by exposure to cold, wet, and wind, coupled with fatigue and hunger.

  BODY HEAT LOSS - The body loses heat in five ways:

1.   Respiration - Heat escapes when air is exhaled. Covering the mouth and nose area with wool or a bandana can reduce this.

2.   Evaporation - Perspiration evaporates from the skin and lungs. Control the amount of evaporation by wearing clothing that can be ventilated or taken off. Wear clothing that will not absorb water, but will breathe.

3.   Conduction - You can lose heat by sitting on the ground or snow, touching cold equipment, or being rained upon. If you become wet a large amount of body heat is lost rapidly. Perspiration or rain reduces your clothing’s insulating value. Wear clothing that will keep you warm even if it is wet, such as wool or the new synthetic materials.

4.   Radiation - Radiation causes the largest heat loss from uncovered skin, particularly the head, neck, and hands. Cover these areas to prevent further heat loss.

5.   Convection - Clothing keeps a layer of warm air next to the skin, and allows water vapor (perspiration) to pass outward. The body continually warms this layer of air. Heat is lost rapidly with the slightest breeze unless you wear a nylon or Gore-Tex shell over your clothing to prevent the warm air from being lost. Wind lowers temperatures due to the increased evaporation and convection. You must have wind protection and good insulating value (dead air space) for your clothing to retain your body heat at a safe level.

DETECTION - If you are exposed to WIND, COLD, or WET, think hypothermia. Watch yourself and others for the symptoms:

1.   Uncontrollable fits of shivering.

2.   Vague, slow, slurred speech.

3.   Memory lapses, or incoherence.

4.   Immobile, fumbling hands.

5.   Frequent stumbling.

6.   Drowsiness (to sleep is to die.)

7.   Apparent exhaustion. Inability to get up after a rest.

TREATMENT - The victim may deny he/she is in trouble. Believe the symptoms, not the person. Even mild symptoms demand immediate treatment.

1.   Get the victim out of the wind and rain.

2.   Strip off all wet clothes.

3.   If the victim is only mildly impaired:

·        Give him/her warm drinks (only small amounts).

·        Get him/her into dry clothes and a warm dry sleeping bag. Well‑wrapped warm (not hot) rocks or canteens placed in the crotch and under the arms anywhere the main arteries are close to the surface of the skin will hasten recovery.

4.   If the patient is semi-conscious or worse:

·        Try to keep him/her awake. (Do not give hot liquids by mouth.)

·        Leave him/her stripped. Put him/her in a sleeping bag with another person (also stripped) to transfer heat. If you can put the victim between two donors, skin-to-skin contact is very effective treatment.

5.   Build a fire to warm canteens and rocks for warming the victim.

6.   Transport the victim as soon as possible to the closest hospital for monitoring. It takes a very long time to warm the inner core. DON'T DELAY!

PREVENTION

1.   AVOID EXPOSURE

·        Stay Dry. When clothes are wet they lose about ninety percent of their insulating value. When wet, wool and the new synthetics retain most of their insulating value. Wet cotton and wet down are worthless.

·        Beware of the Wind. A slight breeze carries heat away from bare skin much faster than still air. Wind drives cold air under and through clothing. It refrigerates wet clothes by evaporating moisture from the surface.

·        Understand Cold. Most hypothermia cases develop in air temperatures between 30 and 50 degrees.

2.   TERMINATE EXPOSURE - If you can not stay dry and warm under existing weather conditions, using the clothes you have with you, do whatever is necessary to be less exposed. Give up reaching your destination and get out of the wind and rain.

3.   BEWARE OF EXHAUSTION AND HUNGER - Exposure greatly reduces your normal endurance. If exhaustion forces you to stop, however brief:

·        Your rate of body heat production instantly drops by fifty percent or more.

·        Shivering may begin immediately.

·        You may slip into hypothermia in a matter of minutes without you realizing it is happening.

·        The body will produce heat by metabolizing food. Eat! Especially carbohydrates. Drink enough water. Dehydration contributes to hypothermia.

4.   NEVER IGNORE SHIVERING - Persistent or violent shivering is a clear warning that you are on the verge of hypothermia. Take Action!

(Adapted from Seattle Mountaineers and other sources)