Along with cooler weather comes wetter weather that you must prepare
for. Getting wet can kill. Even in warm weather getting wet can
cause hypothermia a condition when the core body temperature drops
below 90 F serious complications begin to develop. Hypothermia is
caused by exposure to cold, aggravated by wet, wind, and exhaustion.
It is the number one killer of outdoor enthuestists. Death may occur
at about 80 F; however, a person may drown if immersed at a higher
temperature due to loss of consciousness or inability to use the arms
and legs.
COLD KILLS IN TWO DISTINCT STEPS
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 exposure.
THE TIME TO PREVENT HYPOTHERMIA IS DURING THE PERIOD OF EXPOSURE AND
GRADUAL EXHAUSTION
HYPOTHERMIA
If 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 your hands.
This is hypothermia. Your internal temperature is sliding downward.
Without treatment, this slide leads to stupor, collapse, and death.
AVOID EXPOSURE
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.
TERMINATE EXPOSURE
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.
NEVER IGNORE SHIVERING
Persistent or violent shivering is a clear warning that you are on
the verge of hypothermia. MAKE CAMP OR GET BACK TO YOUR VEHICLE.
BEWARE OF EXHAUSTION
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.
DETECT HYPOTHERMIA
If your group is exposed to WIND, COLD, OR WET, think hypothermia.
Watch yourself and others for the symptoms:
Uncontrollable fits of shivering.
Vague, slow, slurred speech.
Memory lapses, or incoherence.
Immobile, fumbling hands.
Frequent stumbling.
Drowsiness (to sleep is to die.)
Apparent exhaustion. Inability to get up after a rest.
TREATMENT
The victim may deny he/she is in trouble. Believe the symptoms, not
the person. Even mild symptoms demand immediate treatment.
Get the victim out of the wind and rain.
Strip off all wet clothes.
If the victim is only mildly impaired:
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 DELAY!
HYPOTHERMIA IN WATER
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:
WATER TEMPERATURE / EXHAUSTION / SURVIVAL TIME
32.5 degrees..... ......... ......... .....Under 15 min........Under 15
TO 45 min.
32.5 to 40.......... ......... ......... ....15 to 30 min......... 30 to
90 min.
40 to 50.......... ......... ......... .......30 to 60 min......... 1 to
3 hrs.
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
Over
80.......... ......... ......... .......Indefinit e........ .......Indefini
te
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 REMEMBER:
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.
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BODY HEAT LOSS
The body loses heat in five ways: Respiration, Evaporation,
Conduction, Radiation and Convection.
RESPIRATION: Heat escapes when air is exhaled. This can be reduced by
covering the mouth and nose area with wool or a bandana.
EVAPORATION: 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.
CONDUCTION: Sitting 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 insulating pad.
RADIATION: Radiation 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.
CONVECTION: The 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 level.
"No previously healthy person should die of hypothermia after
they have been rescued and treatment has been started."
Cameron C. Bangs, M.D. The Mountaineers 1986.
some facts quoted from
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