Four Lines of Defense Against Hypothermia

Never under estimate the risk of hypothermia when your activities keep you in the elements. What is hypothermia?

Hypothermia is a medical emergency that occurs when your body loses heat faster than it can produce heat, causing a dangerously low body temperature. Normal body temperature is around 98.6 F (37 C). Hypothermia occurs as your body temperature falls below 95 F (35 C).

  • Hypothermia is caused by prolonged exposures to very cold temperatures. When exposed to cold temperatures, your body begins to lose heat faster than it’s produced. Lengthy exposures will eventually use up your body’s stored energy, which leads to lower body temperature.
  • Body temperature that is too low affects the brain, making the victim unable to think clearly or move well. This makes hypothermia especially dangerous, because a person may not know that it’s happening and won’t be able to do anything about it.
  • While hypothermia is most likely at very cold temperatures, it can occur even at cool temperatures between 30 to 50 F ( -1 to 10 C) if a person becomes chilled from rain, sweat, or submersion in cold water. This is the most likely scenario that hunters, hikers, or backpackers would be exposed to.

Cold kills in two distinct steps.

1. Exposure and Exhaustion
The moment that your body begins to lose heat faster than it produces it, you are undergoing exposure. You voluntarily exercise to saty warm and your body makes involuntary adjustments to preserve normal temperature in the vital organs. Either response drains your energy reserves. The only way to stop the drain is to reduce the degree of exposure. The time to prevent hypothermia is now.

2. Hypothermia
If exposure continues until your energy reserves are exhausted, then cold reaches the brain depriving you of judgement and reasoning power. You will not realize that this is happening. You will loose control of your hands. This is hypothermia. your internal temperature is sliding downward. Without treatment, this slide leads to stupor, collapse, and death.

Four lines of Defense

1. Avoid Exposure. Stay dry, beware of the wind, and understand cold.
When clothes get wet they loose about 90% of their insulating value. Wool looses less; cotton, down, and synthetics loose more. A slight breeze carries heat away from bare skin much faster than still air. Wind drives cold air under and through clothing. Wind refrigerates wet clothes by evaporating moisture from the surface. Wind multiplies the problems of staying dry. As mentioned earlier, most hypothermia cases develop when the temperature is between 30 and 50 degrees F. The danger of being wet in this range is fatally underestimated. Put on rain gear before you get wet and put on wool clothes before you start shivering. 

2. Terminate Exposure. Get out of the wind and rain.
Persistent or violent shivering is a clear warning that you are on the verge of hypothermia. Stop all activities and make camp. Build a fire and concentrate on making your camp as comfortable as possible. This takes energy. Exposure greatly reduces your normal endurance. You may think that you are doing fine when the fact that you are exercising is the only thing that may be preventing you from going into hypothermia. If exhaustion forces you to stop, however briefly: your rate of body heat production instantly drops by 50% or more. Violent, incapacitating shivering may begin immediately. You may slip into hypothermia in a manner of minutes.

3. Detect Hypothermia


4. Treatment