If you are outdoors enjoying your
favorite sport, you presumably do not intend to jeopardize your life.
Hypothermia may be a new word to you, but it is the only word that
describes the rapid, progressive mental and physical collapse accompanying the
chilling of the inner core of the human body. Hypothermia is caused by exposure
to cold, aggravated by wet, wind, and exhaustion. It is the number one
killer of outdoor recreationalists
COLD KILLS IN TWO DISTINCT
EXPOSURE AND EXHAUSTION
The moment your body begins
to lose heat faster than it produces it, you are undergoing exposure.
Two things happen:
- You voluntarily
exercise to stay warm.
- Your body makes
involuntary adjustments to preserve normal temperature in the vital
organs, and you start shivering.
Either response drains your
energy reserves. The only way to stop the drain is to reduce the degree of
THE TIME TO PREVENT
HYPOTHERMIA IS DURING THE PERIOD OF EXPOSURE AND GRADUAL EXHAUSTION
exposure continues until your energy reserves are exhausted:
- Cold reaches the brain
depriving you of good judgement and reasoning power. You will not realize
this is happening.
- You will lose control of
This is hypothermia. Your
internal temperature is sliding downward. Without treatment, this slide leads
to stupor, collapse, and death.
- STAY DRY. When clothes
get wet, they lose about ninety percent of their insulating value. Wool loses
less as does many of the new synthetics. Cotton and wet down are worthless.
- BEWARE OF THE WIND. A
slight breeze carries heat away from bare skin much faster than still air. Wind
drives cold air under and through clothing. Wind refrigerates wet
clothes by evaporating moisture from the surface. WIND MULTIPLIES THE
PROBLEMS OF STAYING DRY. If you have been in the water and you are wearing a
T-shirt that is wet remove it and you will retain more heat. Direct sunlight on
the skin helps in the warming process.
- UNDERSTANDING COLD. Most
hypothermia cases develop in air temperatures between 30 and 50 degrees. Most
outdoor enthusiast simply can't believe such temperatures can be dangerous.
They fatally underestimate the danger of being wet at such temperatures. Fifty
degree water is unbearably cold. The cold that kills is cold
water running down your neck and legs, and cold water removing body
heat from the surface of your clothes.
If you can not stay dry
and warm under existing weather conditions, using the clothes you have with
you, do whatever is necessary to be less exposed.
- BE SMART ENOUGH TO GIVE
UP REACHING THE PEAK, OR WHATEVER YOU HAD IN MIND.
- Get out of the wind
and rain. Build a fire. Concentrate on making your camp or bivouac as
secure and comfortable as possible.
Persistent or violent
shivering is a clear warning that you are on the verge of hypothermia. MAKE
CAMP OR GET BACK TO YOUR VEHICLE.
Make camp while you still
have a reserve of energy. Allow for the fact that exposure greatly reduces your
normal endurance. You may think you are doing fine when the fact that you are
exercising is the only thing preventing your going into hypothermia. If
exhaustion forces you to stop, however brief:
- Your rate of body heat
production instantly drops by fifty percent or more.
- Violent, incapacitating
shivering may begin immediately.
- You may slip into
hypothermia in a matter of minutes.
Make the best protected and
experienced member of your party responsible for calling a halt before the
least protected member becomes exhausted or goes into violent shivering.
If your group is exposed
to WIND, COLD, OR WET, think hypothermia. Watch yourself and others for the
- Uncontrollable fits of
- Vague, slow, slurred
- Memory lapses, or
- Immobile, fumbling
- Frequent stumbling.
- Drowsiness (to sleep is
- Apparent exhaustion.
Inability to get up after a rest.
The victim may deny he/she
is in trouble. Believe the symptoms, not the person. Even mild symptoms demand
- Get the victim out of
the wind and rain.
- Strip off all wet
- If the victim is only
- Give him/her warm
drinks. (only small amounts)
- Get him/her into dry
clothes and a warm dry sleeping bag. Well-wrapped warm (not hot) rocks or
canteens placed in the crotch and under the arms anywhere the main arteries are
close to the surface of the skin, will hasten recovery.
- If the patient is
semi-conscious or worse:
- Try to keep him/her
awake. (Do not give hot liquids by mouth.)
- Leave him/her
stripped. Put him/her in a sleeping bag with another person (also stripped) to
transfer heat. If you can put the victim between two donors, skin to skin
contact is very effective treatment.
- Build a fire to warm
canteens and rocks for warming the victim.
- Transport the victim as
soon as possible to the closest hospital for monitoring. It takes a very long
time to warm the inner core and only a rectal hypothermia thermometer is long
enough to find out what the inner core temperature really is. DON'T
Loss of body heat to the
water, is a major cause of deaths in boating accidents. Often the cause of
death is listed as drowning; but, often the primary cause is hypothermia. It
should also be noted that alcohol lowers the body temperature around two to
three degrees by dialateing the blood vesels. Do not drink alcohol around cold
water. The following chart shows the effects of hypothermia in
WATER TEMPERATURE /
EXHAUSTION / SURVIVAL TIME
degrees............................Under 15 min........Under 15 TO 45 min.
32.5 to 40................................15 to 30 min.........30 to 90
40 to 50...................................30 to 60 min.........1 to 3
50 to 60...................................1 to 2 hrs..............1
to 6 hrs.
60 to 70...................................2 to 7
hrs..............2 to 40 hrs.
70 to 80...................................3
to 12 hrs............3 hrs. to indefinite
PFD's (personal flotation
devices / better known as life jackets) can increase survival time because of
the insulating value they provide. In water less than 50 degrees you should
wear a wet suit or dry suit to protect more of the body.
SOME POINTS TO
- While in the water, do
not attempt to swim unless to reach nearby safety. Unnecessary swimming
increases the rate of body heat loss. Keep your head out of the water. This
will increase your survival time.
- Keep a positive attitude
about your rescue. This will increase your chances of survival.
- If there is more than
one person in the water, huddling is recommended.
- Always wear your PFD. It
won't help if you don't have it on.
The body loses heat in five
ways: Respiration, Evaporation, Conduction, Radiation and Convection.
escapes when air is exhaled. This can be reduced by covering the mouth and nose
area with wool or a bandana.
Perspiration evaporates from the skin and moisture from the lungs contributes
to heat loss by the body. Control the amount of evaporation by wearing clothing
that can be ventilated or taken off. Wear clothing that will not absorb water,
but will breathe. So you can control the cooling effect of evaporation.
on the ground, snow, touching cold equipment, or being rained upon are all
examples of how heat can be lost through conduction. If you become wet a large
amount of body heat is lost rapidly. Perspiration or rain should never be
allowed to saturate your clothing which can reduce their insulating values.
Wear clothing that will keep you warm even if it is wet, such as wool or some
of the new synthetic materials (polypropylene, polorguard, fiberfill,
quollofil) have good wet characteristics. Sit or sleep on a closed-cell
causes the largest heat loss from uncovered skin, particularly the head, neck,
and hands. It is important to cover these areas in keeping warm and preventing
further heat loss.
primary function of clothing is to keep a layer of warm air next to the skin,
but allows water vapor (perspiration) to pass outward. The body continually
warms this layer of air close to the body. A wet suit uses this same theory,
but when a person falls into the water you are chilled for a few moments before
the water next to your skin is warmed by your body. A dry suit has less initial
shock because water does not get inside to start with so the clothing you wear
under the dry suit captures the air to retain your warmth. Heat is lost rapidly
with the slightest breeze unless you wear a nylon or gortex shell over your
clothing to prevent the warm air from being lost. The cooling effect of wind
chill is equal to that of much lower temperatures due to the increased
evaporation and convection. You must have wind protection and good insulating
value (dead air space) for your clothing to retain your body heat at a safe