Hypothermia: Quiet Killer of Outdoor Enthusiasts
Even on mild days
by Charlie Powell
Oh, I know, itís a mild early winter day and youíre still out in shirt sleeves on these glorious Idaho December days. You remember hearing about hypothermia before, but youíre not quite sure what it is. Hypothermia is a simple concept with very complex contributing factors and physiological effects.
Harvard University Medical School researchers estimate that more than 2.5 million people risk death from hypothermia each year. The nice thing is you donít need to know all the medical realities of hypothermia in order to perform like an honest-to-goodness expert in the outdoors or emergency situations. In fact, you donít even need a thermometer.
Body Core Temperature
Hypothermia means that a personís body core temperature is below 95 degrees F. Remember, our normal temperature is about 98.6 degrees F. The key word here is core temperature. Core temperature is the temperature inside your trunk and head essentially. Think of your body as a machine that makes itís own heat all the time. It can only generate so much, though, and if the rate of cooling is too great, then core temperature begins to drop. With strenuous activity you generate even more heat but your body begins to compensate by sweating and this affects the rate of cooling too. So as I said, this all gets complex real fast. Keep in mind that in 77 degree F. weather a naked human cannot maintain body temperature without activity.
Thatís right, 77 degrees. From there on, its a balance sheet. For instance. add clothes and you can drop the temperature some, depending on the clothes. Throw water on the person and the temperature will have to be warmer for them to maintain core temperature. Leave the person in the wind and he can be in trouble fast.
In reality, if you throw water on a naked person and place them in the wind, they will probably crouch down with their back to the wind and arms tucked in. This minimizes the surface area that is losing heat. They will involuntarily start to shiver, which we all know is a way your body generates more heat by muscular contraction. So you see, you and nature can just keep adding and subtracting from the balance sheet right on up to real outdoor situations.
Real life scenario
Hereís a real situation that has nothing to do with winter, although most hypothermia incidents do occur then. A group of fly fishermen met at a trailhead leading to the Middle Fork of the Salmon River in the Frank Church River of No Return Wilderness Area. It was about noon in July with the temperature in the upper 70s. The three men and one woman were dressed appropriately in jeans, T-shirts, light cotton long-sleeved shirts and hip waders. The plan was to hike and fish their way in as far as they could but be out by dark. Fishing was excellent, the scenery beyond compare, and they covered about five miles in no time.
The going had been hot though, and all were sweaty when they realized they had left their water at camp. No problem, because they were only going to be gone a few hours. Fishing back out was equally enjoyable but late afternoon was falling and so was the temperature. Remember, how much the temperature falls doesnít matter, if it falls enough.
So, hereís the scene, four fatigued, partially dehydrated people in moist cotton clothes with the clear air temperature dropping quickly, trudge the last couple of miles into camp. This is the perfect set-up for a mild case of hypothermia and it took significant measures to prevent it once they got back.
First, they had to get out of their wet clothes to cut their evaporative cooling. Next, they needed fluids and lots of them. The warmer the better, too, because the heat you take in is used to warm you internally. The United States Army has shown that a dehydration loss of only 10 percent can decrease your ability to control your own temperature by 30-40 percent. Drinking adequate amounts of fluids on a regular basis in the winter is just as important as in the blazing heat of summer. Finally, they needed rest and food around a warming fire while they rehashed the dayís fishing.
This little story is true; one of the members did begin to get some of the symptoms of hypothermia by the time they reached camp. He came around shortly after doing the things mentioned earlier. Without prompt action though, a bad situation could have resulted. Try to remember this example, and how it was summer, warm, no storm, and how a couple of minor mistakes made by all contributed to a potentially dangerous situation.
How do you know?
With winter coming on, hypothermia risks become much greater. So just how do you know if a person is hypothermic?
As with most things, hypothermia is classified by how fast it comes on and what the resulting core temperature is. Most experts agree that field diagnosis of hypothermia is difficult, which is why the average person should concentrate on the preventive side. There are some rules of thumb; however, not all victims will behave this way.
Shivering may occur at core temperatures of 97 degrees or below. From 97 degrees to 95 degrees, we all feel cold, have goosebumps, and shivering may be mild to severe with skin numbness. From 95 degrees down to 93 degrees, shivering becomes intense, movements are slow and labored, mild confusion may set in, muscles will be uncoordinated, and most importantly, the person will be unable to walk a 30í straight line. The straight line test is the most important field test for early hypothermia. So there it is, this is all you need to remember.
What to do
If you or someone you know approaches these symptoms or worse, such as loss of speech, or if shivering stops, immediate but proper action must be undertaken
First, you must stop what you are doing and care for yourself or the other person. You are on the verge of a true medical emergency when you think hypothermia is setting in and you should take control of the situation; not in a moment -- Now!
Next, the patient must be kept dry. Wet clothing must be removed and replaced with dry articles. Warm, dry blankets or sleeping bags can be used if no more clothes are available. It is especially important to cover the head since a major loss of body heat occurs there.
Putting a person in warm clothes or a blanket will not do it alone. The person must come in contact with an external source of heat since core temperature may continue to drop for a couple of hours after these measures are started. No doubt, the best source of external heat is probably the inside of your rig while it is on its way back into town with the heater on full. Common sense, once again. Blazing fires with something behind the victim to reflect the heat work well. One that always gets a snicker is the two-people-in- one-sleeping-bag-trick. Hey, donít laugh, it works very well and its success is well documented among mountaineers.
Warm fluids are good to give, but only after the patient has stopped the uncontrollable shivering. Think about it. If the patient canít control the muscles causing the shivering then he probably canít control the muscles in his throat well enough to drink safely either. You certainly donít need to compound the hypothermia with fluids in the lungs.
What NOT to do
While on the subject of fluids, never give someone suspected of being hypothermic any alcohol. This is folklore medicine that doesnít work. Alcohol will lower core temperature drastically by enlarging the blood vessels in the extremities and face, causing that familiar rosy glow. That glow is the last bit of warm blood from your core coming to the surface and literally radiating your lifeís heat away. Caffeine in coffee can be devastating too and should be avoided. Hot chocolate, cocoa, apple cider, tea, lemonade and others make better choices. Donít forget heating plain water in a pinch.
Now for a few things not to do besides the alcohol and coffee. Donít handle patients roughly. Be gentle but firm in your care. Rough handling of patients with severe hypothermia can lead to fatal heart problems right then. Donít rub a victimís arms and legs; walk them around in circles, or plunge them in warm water baths, or showers. These "doníts" are all things done in the old television reruns, they have no basis in fact, and they can be deadly.
THINK before you go
The best thing you can do to protect yourself and partners from hypothermia is to think about it before you go. Bring along the extra gear to deal with such an emergency. Think about it while you are out there. Is the weather changing? Why is my friend lagging so far back and walking funny? Think about it if it happens. Common sense should shout out what youíve learned here and you should get to help soon. Chances are with just thinking about what you now know, youíll never have to deal with this silent killer.
See also: Outdoor Action Guide to Hypothermia and Cold Weather Injuries by Rick Curtis