By Randy Gerke
Copyright 1993

The silent killer, hypothermia, takes many lives each year. A hundred years ago hypothermia was not understood. Many people died from it, but no one actually understood what it was. Those deaths were usually attributed to other causes. Until recently, little was known about the causes and effects of hypothermia. To understand how to prevent and treat hypothermia, we must first explore the causes.

The body is an intricate collection of organs and systems. These systems operate most efficiently at a temperature of near 98.6 F. They are also very sensitive to the smallest changes in temperature. Whenever the core temperature of the body goes up or down these systems begin to fail. Specifically, hypothermia means the lowering of the body's core temperature to a level at which the body begins to fail. This is considered to happen at a core temperature of 95 F degrees.

Heat Production

The body produces heat by the digestion and utilization of food. This is the main fuel source for the body's furnace. Additional heat is produces during an increased rate of exercise. Shivering is a natural mechanism that creates involuntary exercise and produces heat. The amount of heat produced from shivering is dependent upon the severity of shivering and the amount of fuel consumed by muscle activity. The body also gains heat from several external sources as well. These include, warm food and drink, fire, sun, and many others. The human body also has mechanisms to conserve heat. When the skin senses cold temperatures, this information is relayed to the brain. The brain then begins the action of pulling blood away from the surface, and bringing it to the core where it can be used to keep the vital organs at their normal temperature. This reduced blood flow to the body's shell causes decreased function to the extremities. A minimal decrease in function of fine coordination and dexterity are normal as the body initially responds to the cold.

Heat Loss

There are five ways our bodies lose heat.


Most of the heat loss from the body occurs through radiation. The body constantly radiates heat which is passed into the surrounding air. The major area of concern is the head. The head is provided with a large number of blood vessels, so that the brain will have an adequate blood supply. This blood system is located very close to the surface of the skin. Because of this, the majority of heat that the body produces is lost from the heat and neck area during cold conditions. Heat is also lost from any other exposed part of the body.


A substantial amount of heat is lost as exhaled warm air. This is an unpreventable fact of life. We can help to prewarm the air we breath by wearing a light covering over the nose and mouth.


Any time the body cones in contact with a substance of lower temperature, heat is lost by way of conduction. This is why immersion in water is a very dangerous situation. During extremely cold conditions, the conduction from skin to metal is rapid and serious. Every precaution should be observed, not to touch bare skin to metal in these conditions. Gloves or mittens should always be worn.


The evaporation of perspiration from the skin, and the escape of vapor from the lungs adds to the reduction of heat. These are normal body functions and cannot be prevented, although they can be controlled by keeping clothes dry by proper use of the layering system.


Our bodies produce enough heat to warm the air immediately surrounding the skin. If we are not properly clothed, we lose this heat by convection to the outside air. Windy conditions increase the effects of convection. Again, by proper use of the layering system, we are able to trap this warm air close to the body.

Other Factors

There are other factors which decrease the body's defenses against cold. Windchill is one of the most deadly effects. Even a slight breeze at low temperature can, in effect, drop the temperature considerably. Combine this with the presence of water chill and the results can be tragic. The thermal conductivity of water is 240 times greater than still air. Wet clothing can extract body heat at a rate of 240 times greater than dry clothing. It is imperative that dry clothing always be available.

When Does Hypothermia Occur

Many people think that hypothermia occurs only in an extreme arctic environment. This is a false idea and has led to the death of many. Many deaths happen at temperatures of 40 or 50 degrees F. With a combination of wet clothing and a breeze people are prime targets for hypothermia. Even on mild days, the possibility exists that conditions may change rapidly. Be prepared With addition clothing and weather protection. Many people survive the effects of hypothermia each year because they recognize the early warning signs and begin immediate treatment. Other people who are unprepared and uneducated as to the effects of hypothermia have died in 50 degree weather. The following highlights symptoms for both mild and severe hypothermia, treatment and prevention.

Warning Signs (Mild Hypothermia-core temperature above 90 degrees)

  • Uncontrollable shivering
  • Slurred speech
  • Impaired judgment
  • Slowed reflexes
  • Loss of coordination

Severe Hypothermia (core temperature below 90 degrees)

  • Decreased shivering
  • Muscular rigidity
  • Pale or blue skin
  • Weak, slow and irregular pulse
  • Confusion and memory loss
  • Unconsciousness


The key to successful treatment of hypothermia is early detection , in others as well as yourself . Learn the warning signs and act quickly . No job or activity is more important than your personal safety. If you wait, it may be too late.

If you are in a group, watch each other closely for the symptoms of hypothermia. You may notice a problem with one member of you group, and he may tell you he is fine. Don't believe it . Take immediate action. Remember, it takes only minutes to slip into hypothermia, and less than 2 hours to die from it . There are several steps to follow when treating a hypothermia victim.

Treatment of Mild Hypothermia

Quick and aggressive field re-warming is the key to successful treatment for mild hypothermia.

  • Reduce the cold challenge- Find or build shelter to block wind and precipitation
  • Remove wet clothing
  • Increase heat production by adding fuel to the internal furnace. Start by eating simple sugars then add complex carbohydrates and work up to fats and proteins.
  • Replace fluids. Calories from food cannot be effectively utilized in a dehydrated condition. Drinking cool or cold water will not cause additional harm to a hypothermic person. Warm liquids such as water, herb tea, or broth can be used if available. Do not eat snow, and avoid giving sports drinks to a hypothermic person. The concentration of electrolytes make them difficult to absorb and may cause other problems during the re-warming process. Avoid heavily sweetened or caffeinated drinks.
  • Add external heat
  • Huddle as a group around a person with the early stages of hypothermia. This provides shelter, and also transfers heat by radiation and conduction.
  • Cuddle with another person to conserve and share body heat
  • Utilize radiant heat from a fire, candles or chemical heat packets. The most effective use of heat packs is to place them on areas with concentrated blood flow near the surface of the skin, such as, the neck, under the arms and crotch. Cold skin is extremely sensitive to heat injury and should be protected. Cover heat packs in a dry sock, or wrap them in cloth before placing them on the skin.
  • Skin to skin contact is a very efficient method of heat transfer using the principle of conduction. An effective way to do this is to place the hypothermic person together with a rescuer who is not hypothermic in a sleeping bag or 2 bags zipped together. Both patient and rescuer then remove all clothes and cuddle together. Care should be taken that the rescuer doesn�t become hypothermic while attempting to re-warm the patient. If more than one rescuer is available, take turns warming the patient.
  • Increase heat production by exercising. This burns calories more quickly, producing more heat. Walking, hiking, or just standing or lying in place doing some form of exercise will accomplish this.

Treatment of Severe Hypothermia

When the body has reached a level of severe hypothermia, it no longer has the ability to warm itself, and without intervention, death will occur. When the core temperature falls below 90�F a controlled re-warming procedure is required which can only be effectively accomplished at a medical facility. Any exercise or sudden re-warming causes can have lethal consequences. The primary field treatment for severe hypothermia is not re-warming, but preventing further heat loss during evacuation.

Rapid Evacuation Guidelines

  • Gentle treatment is critical. No rough handling, jostling or dropping.
  • Do not attempt to re-warm
  • Reduce the cold challenge. Find or build shelter.
  • Remove all wet clothes and replace with dry layers
  • Do not add external heat, such as, heat packs, skin-to-skin conduction, radiant heat from fire, heat from a vehicle heater, etc.
  • Do not actively exercise the patient. Do not allow the patient to walk, and don�t rub the extremities to promote circulation.
  • Keep the patient lying flat during evacuation
  • Patient should be packaged in a weather tight wrap during evacuation to reduce the cold challenge and prevent further heat loss.

Prolonged Treatment Guidelines

If rapid evacuation is not possible, it�s appropriate to carefully initiate field treatment. This is a slow process and may take as long as 24 hours. Follow these guidelines.

  • Gentle treatment is critical. No rough handling, jostling or dropping.
  • Reduce the cold challenge. Find or build shelter.
  • Remove all wet clothes and replace with dry layers
  • Add external heat very slowly. Use methods such as, skin-to-skin conduction, heat packs, and radiant heat from fire. Apply these methods conservatively and slowly.
  • Do not actively exercise the patient
  • Keep the patient lying flat during the re-warming process
  • If the patient is conscious and can swallow, food and liquid can be given in small amounts. As the level of consciousness improve, more food and liquid can be given. Never attempt to give food or liquids to an unconscious person.
  • Never give up on what may appear to be a hopeless hypothermia patient. They�re not dead until they�re warm and dead.


The best method of prevention is to be prepares for the worst conditions, no matter what the conditions are at the time you look out of the window. Anticipate every problem which may arise and be prepared for it. The best defense against hypothermia is to understand it. The next step is to use the layering system . Always carry extra clothes with you. This may save your life. It's also important to keep the body's furnace stoked with fuel. By eating easily digested food such as carbohydrates, frequently throughout the day, the body can maintain it's normal heat production. Keep your body hydrated. Force yourself to drink fluids on cold days. The body can't effectively use the food it has without the proper amount of fluid in the system. Always carry emergency gear with you. And don't drink alcohol.

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