Hypothermia - Play it Cool

By Stephen L. Hicken

More Detailed Article Available By Greg L.Turner - hypothco.htm

Outdoorsman and particularly cavers face many potential hazards in their activities. One risk often overlooked is that of hypothermia. This risk exists all year round, especially for cavers because of the environments they visit. It can turn an otherwise great excursion into an ordeal. Some forethought and understanding of the problem can evade most of the difficulties.

The body has a narrow temperature range in which it can function. It tries to regulate the core body temperature within very narrow limits, close to 98.6 ° F. If the body can’t maintain this temperature, functions quickly begin to decline. Symptoms can come on very gradually and be very subtle or in other instances come on rapidly with extreme incapacitation and even death. Understanding the mechanisms of heat loss can help one prevent and treat hypothermia.

There are 4 general methods by which heat is lost from the body. These include: Conduction, Convection, Radiation, and Evaporation.

· Conduction is probably the most important of these. This is where heat is lost to the surrounding environment through direct contact. This can be body contact with the walls or floors of caves, contact with the air, and most rapidly with water contact or immersion.

· Convection is the loss of heat due to movement of air or water. Wind chill factors are a good example of an effective temperature change.

· Bodies radiate heat to the surrounding environment dependent on the surface area of the person and the ambient temperature difference.

· Evaporation is accomplished by insensible perspiring, breathing, and sweating.

Prevention

The best treatment for hypothermia is prevention, taking precautions in advance. Important factors include proper insulation, proper fuel intake, adequate hydration, good conditioning, avoidance or protection from hazards, avoidance of alcohol, smoking and drugs.

· Insulation is very important particularly for the head and neck area. These two areas can account for about 75% of heat loss. The trunk is next in importance. The body tries to conserve core body temperature by slowing down circulation in the extremities. This is not done in the head for obvious reasons. Wearing a hat and clothing that covers the neck can help greatly to conserve heat.

· The body generates heat by burning fuel - food. When food stores drop, the amount of heat being generated can not be maintained. Ready fuel supplies such as candies give a quick source of energy. Proteins and complex carbohydrates give a more prolonged energy source. Both are important to have available.

· Fluids are necessary to maintain the blood volume and circulation. The body is constantly loosing fluids that need to be replaced. As one becomes dehydrated, he becomes much more susceptible to hypothermia.

· Conditioning helps the body become more efficient, thereby conserving energy. A well conditioned individual can tolerate more stress.

· Extreme hazards for hypothermia include moisture and wind. When one gets wet, heat is quickly whisked away by conduction and evaporation and if in a current by convection. Avoidance of moisture is extremely important. Changing or drying out clothes can be critical at times.

· Alcohol causes blood vessels to open up and exchange heat more rapidly. Certain drugs including nicotine from cigarettes have an effect on the bodies blood flow or regulatory mechanisms and can cause more rapid hypothermia. Caffeine acts as a water pill to increase fluid losses. These things should be avoided if one is to be exposed to the elements.

Recognition

Early recognition of hypothermia is mandatory to prevent a true emergency or disaster. Often times a person may not recognize the symptoms coming on himself. His companions need to be alert for subtle changes before the person becomes incapacitated.

· (98-95°) Mild hypothermia may be manifested by shivering. This can progress into goosebumps, trouble with fine motor coordination, hands may get numb and clumsy, thinking and concentration may start to slow down. Not all people will shiver.

· (95-90°) As the symptoms worsen shivering may be uncontrollable. The person starts to loose coordination, may stumble more often, judgment becomes impaired, amnesia may occur, speech may begin to slur. Intervention becomes critical here.

· (90-86°) Shivering will stop, capacity to walk impaired, confusion and irrational behavior.

· (86-80°) Person drifts into unconsciousness, muscles are rigid, heart rate and breathing slow down, reflexes are lost, voluntary movement not possible, pupils dilate.

· (80-70°) Unconscious, pulse may not be detectable, heart rate erratic, death may ensue.

Treatment

The earlier that symptoms are recognized and treated, the better off the person will be. Each caver should be aware of his own status and take steps to treat himself early and prevent further heat loss. In some circumstances, companions will have to institute treatment.

· It is imperative to reduce heat loss. Wet clothing should be changed and the person insulated as best as possible. Drafts and wet areas should be avoided. Don’t forget to insulate from the floors and walls. Be sure head an neck areas are protected.

· Early on a person may be able to increase their activity and thus produce more body heat.

· If the person is alert, he should be given high energy foods and warmed liquids. Hydration is important if the person has been exerting and sweating a lot.

· External heat sources may be used such as hot packs under the arms, a heating tent (e.g. garbage bag with heat source).

· Reflective blanket may be wrapped around the person to help reduce radiant heat loss.

· Get the person to a warm environment as soon as possible.

Precautions

Any person that has reached a moderate to severe hypothermia (<95°) should be treated with care. Sudden warming of the extremities or significant jostling of a hypothermic person may cause increase risk of death. Toxins and acids accumulate in the extremities during hypothermia and can be returned to the central circulation with disastrous results.

Comment

Most of us have probably experienced some degree of hypothermia in our lives. Hopefully we are wise enough to recognized the danger and take the proper steps to ensure an early recovery. As fellow cavers we should be alert and supportive of one who needs treatment.