WHAT IS IT AND HOW DOES IT KILL?

HYPOTHERMIA

What is it, and how does it kill?

Hypothermia is subnormal temperature within the central body. When a person is immersed in cold water, the skin and nearby tissues cool very fast. However, it may take 1 0 to 1 5 minutes before the temperature of the heart and brain starts to drop. When the core temperature drops below 900F. serious complications begin to develop. Death may occur at about 800 F.; however, a person may drown at a higher temperature because he loses consciousness or loses the use of his arms and legs.

How long can one survive in cold water?

Survival in cold water depends on many factors. The temperature of the water is only one. Others include body size, fat, and activity in the water to name a few. Large people cool slower than small people. Fat people cool slower than thin people. Children, because they are small, cool faster than adults.

By swimming or treading water, a person will cool about 35% faster than if remaining still. The "drownproofing technique" requires putting the head into the water. Because the head is an area of high heat loss, drownproofing will cause a person to cool about 80% faster than if he kept his head out of the water. Drownproofing thus reduces survival time by nearly one half in cold water.

An "average" person, wearing light clothing and a PFD , may survive 2 ½ to 3 hours in 50⁰F water by remaining still. This survival time can be increased considerably by getting as far out of the water as possible and covering the head. Getting into or onto the boat or anything else that floats can be a real life saver. The following table shows predicted survival times for an average person in 50⁰F water.

Situation	Predicted Survival Time (Hours)
NO FLOATATION
Drownproofing Treading Water	1.5 2.0
FLOATATION
Swimming Holding-still H.E.L.P Huddle	2.0 2.7 4.0 4.0

WHAT DO I DO

if an accident does happen?

In case of accidental immersion in cold water, remember that water conducts heat many times faster than air. Most boats sill float even when capsized or swamped. Therefore, get in or on the boat to get as far out of the water as possible. Wearing a PFD is a MUST. It will keep you afloat even if you are unconscious. Remaining still and, if possible, assuming the fetal, or heat escape lessening posture (graphic at the left top of this page) will increase your survival time. About 50 % of the heat is lost from the head. It is therefore important to keep the head out of the water. Other areas of high heat loss are the neck, the sides and the groin.

Note: It is possible to assume the Help position while wearing some PFDs. However, even a partial HELP position gives some protection to the high heat loss areas, thus increasing survival time.

If there are several people in the water, huddling close, side to side in a circle, will also
help preserve body heat.

Placing children in the middle of the circle will lend them some of the adult body heat and extend their survival time.

SHOULD I SWIM FOR SHORE?

This is a most difficult decision. It depends on many things. Some good swimmers have been able to swim 8/10's of a mile in 50^oF water before being overcome by hypothermia. Others have not been able to swim 100 yards. Furthermore, distances on the water are very deceptive. Therefore, STAY WITH THE BOAT. Even a capsized boat is easier to see than a person in the water. This will make it easier for rescuers to spot you. DO NOT SWIM unless there is absolutely no chance of rescue and you are absolutely CERTAIN you can make it. If you do swim, use a PFD or some other flotation aid.

FIRST AID FOR HYPOTHERMIA VICTIMS

1. ) Make sure the victim has an open airway and is able to breathe. Then check for respiration and pulse. Respiration may be slow and shallow and the pulse may be very weak. So check these vital signs very carefully. If there is no pulse or respiration, CPR must be started immediately.

2. ) Prevent further heat loss:

1. Gently move the victim to shelter and warmth as rapidly as possible
2. Gently remove all wet clothing; cut it away if necessary. The feeble amount of heat energy the victim has left must not be expended on warming and drying wet clothing.
3. Wrap the victim in blankets or a sleeping bag. If available, place warm water bottles or other gentle sources of heat under the blanket on victim's neck, groin, and on the sides of his chest.
4. ) Transport the victim to a hospital as soon as possible. Only a physician should determine when the patient should be released.

Incorrect treatment of hypothermia victims may induce a condition known as "AfterDrop". "After-Drop" is a continued fall in the victim's core temperature even after he has been rescued. This is caused by improper re-warming, allowing cold, stagnant blood from the extremities to return to the core of the body. When this cold blood returns to the core of the body it may drop the core temperature below a level which will sustain life. For the same reason, hypothermia victims must be handled gently and should not be allowed to walk.

DO NOT:

1. Place an unconscious victim in a bath tub.

2. Give a victim anything to drink, including hot liquids and especially alcohol.

3. Rub the victim's skin, especially do not rub it with snow.

How can I avoid Hypothermia?

Since most boaters that die in water related accidents had no intention of going in the water, the obvious answer is to avoid those behaviors that cause accidental immersion. Therefore,

DO NOT:

Stand or move around in a small boat.

Overload your boat or distribute the ldhd unevenly.

Decelerate suddenly, allowing the sternwake to overtake and swamp the boat by washing over the transom.

This article was extracted from the Department of Transportation U.S. Coast Guard pamphlet (which was partially extracted from "Man In Cold Water" by Dr. Martin Collis, University of Victoria, British Columbia, Canada.)

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