HYPOTHERMIA: KILLER OF THE UNPREPARED

"To survive it is often necessary to fight and to fight you have to dirty yourself."
-George Orwell

Exposure is a term that crops up every winter and often during warmer times of the year. Exposure has no definite medical meaning but is probably a substitute for the word hypothermia. Have you ever been so cold that you could not stop shivering? Uncontrolled shivering is one of the first signs of hypothermia or the lowering of the inner core temperature of the body. As the condition progresses, there is an increasing lack of coordination followed by loss of judgment and a fairly rapid descent into unconsciousness and death. An unprepared person may become a victim at temperatures as high as 45 degrees F. In cases affecting hunters or hikers a combination of four factors are usually present:

• Cold (45 deg or below)
• Wetness (caused by rain, snow, immersion or condensed perspiration)
• Wind (chill factor)
• A likely victim (meaning a person who is exhausted and certainly unprepared to protect himself or herself)

Good clothing, adequate knowledge, emergency shelter and emergency rations would prevent most fatalities from accidental hypothermia. This is why hypothermia is called the "Killer of the Unprepared". Immediate steps should be taken if you or one of your companions shows signs of uncontrolled shivering. Warming of the body and intake of warm liquids (do not take or give alcoholic beverages) and quick energy foods are recommended to restore body functions to normal. Know your enemy. Never underestimate the power of cold, dampness and wind. Do not over-estimate your own strength or that of those in your party. One individual approaching a hypothermic state can pin you to a location exposed to the elements, so check and re-check for the tell tale signs of hypothermia anytime you are in a cold climate.

Hypothermia is a temperature related disorder. Therefore, it is necessary to understand human physiology as it pertains to temperature stress. Man is considered to be a tropical animal. Normal functioning of the human animal requires a body temperature around 98.6 degrees Fahrenheit. The body can self-compensate for small upward or downward variations in temperature through the activation of a built-in thermoregulatory system, controlled by temperature sensors in the skin. The response to an upward variation in body temperature is the initiation of perspiration, which moves moisture from body tissues to the body surface. When the moisture reaches the surface it evaporates, carrying with it a quantity of heat. The explanation for a person becoming thirsty when exposed to a hot environment for a period of time is that fluids lost due to perspiration must be replaced. The response to a downward variation in body temperature is shivering, which is the body's attempt to generate heat. Shivering is an involuntary contraction and expansion of muscle tissue occurring on a large scale. This muscle action creates heat through friction.

Hypothermia is also considered the clinical state of sub-normal temperature when the body is unable to generate sufficient heat to efficiently maintain functions. Many variables contribute to the development of hypothermia. Age, health, nutrition, body size, exhaustion, exposure, duration of exposure, wind, temperature, wetness, medication and intoxicants may decrease heat production, increase heat loss, or interfere with thermo stability. The healthy individual's compensatory responses to heat loss via conduction, convection, radiation, evaporation and respiration may be overwhelmed by exposure. Medications may interfere with thermoregulation. Acute or chronic central nervous system processes may decrease the efficiency of thermoregulation.

Here are the definitions of the primary causes of body heat loss:

• Conduction: Direct transfer of heat by contact with a cooler object and the conduction of heat to the cooler object.
• Convection: Cool air moving across the surface of the body, heat transferred to the cool air, warming it and cooling the body.
• Radiation: Heat radiated outward from the warm body to the cooler environment.
• Evaporation: The loss of heat through the process of removing water from the surface of the body through vaporization.
• Respiration: Air inside your lungs raised to current body temperature and then exhaled.

Each of these factors causes heat loss and plays a role in the onset of hypothermia, depending on clothing, head cover, wind, weather, etc.

BE AWARE – BE PREPARED – BE SAFE