Preventing Illness and Injury
Hypothermia

Symptoms

Scouts loaded into canoes on a lake in Tweedsmuir Park, British Columbia. A warm breeze blew across the water. But during the day the temperature dropped and there developed a mild drizzle. Gordon, dressed in a cotton T-shirt and swimming trunks, was intent on being the lead canoe of the armada so he was unaware of the weather change. His canoeing buddy noted that his paddle strokes had become sloppy and uncoordinated. He began to act stupidly, suggesting that they ram one of the canoes and start a water fight. When they arrived at the evening's campsite Gordon had lost all interest in camp activities. His buddy noticed that his skin was pale and his lips and fingertips were blue. Then he started shaking uncontrollably and had difficulty staying on the narrow trail leading from the campsite. In a slurred tongue, his answer to requests of Scouts trying to help him was, "Just leave me behind, I'll catch up".

Why

As a warm-blooded species we are good at shedding heat but poor at conserving it. There are two major internal sources of heat. As you are reading this your body is maintaining its core temperature via "basal metabolism". Anything requiring the use of muscles kicks in your second heat source, "exercise metabolism". Gordon was producing heat at roughly 5 times basal level with his involuntary shivering. But this could only last a few hours, at which time his shivering muscles would be exhausted. His brain had initiated his body's primary mechanism to stop further heat loss: vasoconstriction of peripheral circulation. Soon he would stop shivering and hypothermia would become more rapid and very serious.

How

Body heat is lost in five ways: 1) Chilling by direct contact (conduction) is the most severe form. Gordon's wet clothes caused a five-fold increase in his heat loss. Had he fallen into icy water he would have increased his heat loss 25-fold. 2) Heat loss by air movement (convection) is measured by the "wind chill factor", meaning the harder the wind blows that faster you lose heat. Combining wind chill with rain or snow is a double whammy. 3) Heat loss by infrared energy emission (radiation) occurs on cold nights when you shed massive amounts of heat. 4) Minor heat loss occurs by your body's conversion of liquid sweat to gas (evaporation). This is a useful cooling mechanism on hot days, but is contributes to hypothermia when the temperature drops. And, likewise, 5) heat loss through exhaling heated air from your lungs (respiration).

Treatment

Acute hypothermia: Let say Gordon was kayaking on a glacier bay off the north Pacific coast and he fell in. His heat loss is 25 - 50 fold and he has perhaps 5 minutes to live if he is not rescued. Within 30 seconds to a minute he loses function, which means he cannot help himself by climbing out of the water onto his kayak or onto shore. Gordon has to be pulled from the water or he will die.

Moderate hypothermia: Moderate hypothermia has been termed "a case of the umbles"; the Scout fumbles, grumbles, stumbles and later mumbles. His fine motor skills, such as zipping up a parka decrease. He begins to draw inward, becoming less sociable. Normal thinking and judgment become impaired. As his core temperature continues to fall the intensity of the Scout's shivering can become violent. If not properly treated heat rushes from the Scout. His speech becomes slurred and his confusion and stumbling increases. Severe hypothermia, possibly death, is pending if the Scout is not treated. Never leave a victim of even mild hypothermia to fend for themselves.

The most important treatment is to change the Scouts environment from cold and wet to warm and dry. Immediately replace damp clothing with dry clothing. You may not feel the moisture in his clothing, but assume it is damp. Add extra insulation under and around the patient. Add a windproof/waterproof layer and/or place the Scout within a shelter. Once he is thickly bundled in dry insulation he will re-warm. An open fire may increase patient comfort psychologically but it does not increase the rate the Scout re-warms. Shivering inside dry insulation is the fastest way of re-warming.

The addition of heat via snuggling with a warm rescuer does not increase the rate of re-warming. The use of heat packs or hot water bottles does. This heat works best when applied to the palms of hands and soles of feet. Some type of dry material, such as a bandanna, should separate the heat pack from direct contact. A mildly hypothermic Scout may be encouraged to exercise once he has put on dry clothing. To stoke the inner fire of the mild or moderately hypothermic Scout, give water and food. As long as the Scout returns to normal an evacuation is not necessary. The Scout, however, may be exhausted, requiring a rest day to re-hydrate and refuel.

Preventing Hypothermia

1. Carry adequate food and clothing. Anticipate the worst possible weather conditions. Dress in layers. Carry windproof and waterproof outer garments, mittens or gloves and a hat (in cold weather over 50% of generated heat may be lost by radiation from an uncovered head). Polypropylene (next to your skin) under a nylon windbreak is an effective layering combination. Polypropylene can keep you warm even if it gets wet. Avoid cotton; if it gets wet it stays wet and cold.
2. Do not exhaust yourself in cold weather. Avoid becoming overheated and perspiring in cold weather. Do not sit down in the snow without insulation under you.
3. Seek shelter in times of extreme cold and high winds.
4. Do not become dehydrated. Ingesting show is an inefficient way to replace water as it worsens hypothermia.
5. Do not skip meals.

Early warning: There are a couple of simple tests you can do to yourself. 1) If you ordinarily can whistle, try to; if you can't you are hypothermic and better do something about it. 2) Try to button or un-button an item of clothing; if you can't, again, you are hypothermic and should take action.

But there is a peculiarity of this condition; because it affects your mental processes early on, you may be the last to know you have it. So you can hope your buddy will notice your symptoms, as did Gordon's canoe mate. Indeed, do look unto others as you would have them do unto you; be on the lookout for your fellow Scouts who may be hypothermic. Better yet, help everybody to be prepared for cold and thus avoid this insidious and dangerous disease.