HYPOTHERMIA-The Big Chill
By Randy Gerke
Copyright 1993
The silent killer, hypothermia, takes many lives each year. A hundred years
ago hypothermia was not understood. Many people died from it, but no one actually
understood what it was. Those deaths were usually attributed to other causes. Until
recently, little was known about the causes and effects of hypothermia. To understand
how to prevent and treat hypothermia, we must first explore the causes.
The body is an intricate collection of organs and systems. These systems operate
most efficiently at a temperature of near 98.6 F. They are also very sensitive to
the smallest changes in temperature. Whenever the core temperature of the body goes
up or down these systems begin to fail. Specifically, hypothermia means the lowering
of the body's core temperature to a level at which the body begins to fail. This is considered to happen at a core temperature of 95 F degrees.
Heat Production
The body produces heat by the digestion and utilization of food. This is the
main fuel source for the body's furnace. Additional heat is produces during an increased
rate of exercise. Shivering is a natural mechanism that creates involuntary exercise and produces heat. The amount of heat produced from shivering is dependent upon
the severity of shivering and the amount of fuel consumed by muscle activity. The
body also gains heat from several external sources as well. These include, warm
food and drink, fire, sun, and many others. The human body also has mechanisms to conserve
heat. When the skin senses cold temperatures, this information is relayed to the
brain. The brain then begins the action of pulling blood away from the surface,
and bringing it to the core where it can be used to keep the vital organs at their normal temperature.
This reduced blood flow to the body's shell causes decreased function to the extremities.
A minimal decrease in function of fine coordination and dexterity are normal as the body initially responds to the cold.
Heat Loss
There are five ways our bodies lose heat.
Radiation
Most of the heat loss from the body occurs through radiation. The body constantly
radiates heat which is passed into the surrounding air. The major area of concern
is the head. The head is provided with a large number of blood vessels, so that
the brain will have an adequate blood supply. This blood system is located very close
to the surface of the skin. Because of this, the majority of heat that the body produces
is lost from the heat and neck area during cold conditions. Heat is also lost from
any other exposed part of the body.
Respiration
A substantial amount of heat is lost as exhaled warm air. This is an unpreventable
fact of life. We can help to prewarm the air we breath by wearing a light covering
over the nose and mouth.
Conduction
Any time the body cones in contact with a substance of lower temperature, heat
is lost by way of conduction. This is why immersion in water is a very dangerous
situation. During extremely cold conditions, the conduction from skin to metal is
rapid and serious. Every precaution should be observed, not to touch bare skin to metal in
these conditions. Gloves or mittens should always be worn.
Evaporation
The evaporation of perspiration from the skin, and the escape of vapor from the
lungs adds to the reduction of heat. These are normal body functions and cannot
be prevented, although they can be controlled by keeping clothes dry by proper use
of the layering system.
Convection
Our bodies produce enough heat to warm the air immediately surrounding the skin.
If we are not properly clothed, we lose this heat by convection to the outside air.
Windy conditions increase the effects of convection. Again, by proper use of the
layering system, we are able to trap this warm air close to the body.
Other Factors
There are other factors which decrease the body's defenses against cold. Windchill
is one of the most deadly effects. Even a slight breeze at low temperature can,
in effect, drop the temperature considerably. Combine this with the presence
of water chill and the results can be tragic. The thermal conductivity of water is
240 times greater than still air. Wet clothing can extract body heat at a rate
of 240 times greater than dry clothing. It is imperative that dry clothing always
be available.
When Does Hypothermia Occur
Many people think that hypothermia occurs only in an extreme arctic environment.
This is a false idea and has led to the death of many. Many deaths happen
at temperatures of 40 or 50 degrees F. With a combination of wet clothing and a
breeze people are prime targets for hypothermia. Even on mild days, the possibility exists
that conditions may change rapidly. Be prepared With addition clothing and weather
protection. Many people survive the effects of hypothermia each year because they
recognize the early warning signs and begin immediate treatment. Other people who
are unprepared and uneducated as to the effects of hypothermia have died in 50 degree
weather. The following highlights symptoms for both mild and severe hypothermia,
treatment and prevention.
Warning Signs
Mild Hypothermia (core temperature above 90 degrees)
Uncontrollable shivering
Slurred speech
Impaired judgment
Slowed reflexes, loss of coordination
Severe Hypothermia ( core temperature below 90 degrees)
Decreased shivering, victim feels warmer
Muscular rigidity
Pale or blue skin
Weak, slow and irregular pulse
Confusion, memory loss
Treatment
The key to successful treatment of hypothermia is early detection , in others
as well as yourself . Learn the warning signs and act quickly . No job is more
important than your personal safety. If you wait, it may be too late.
If you are in a group, watch each other closely for the symptoms of hypothermia.
You may notice a problem with one member of you group, and he may tell you he is
fine. Don't believe it . Take immediate action. Remember, it takes only minutes
to slip into hypothermia, and less than 2 hours to die from it . There are several
steps to follow when treating a hypothermia victim.
Mild Hypothermia
Shelter from wind and cold
Build a fire or produce heat (use candles or other chemical heat source, or
huddle together with other warm bodies)
Remove wet clothing
Drink warm fluids
Exercise
Eat food - Start with simple carbohydrates such as candy and work up to more
complex foods. Think in terms of building a fire. Kindling= simple sugars such
as candy, hot chocolate etc. Like kindling they are quick to burn but not long lasting.
Sticks = complex carbohydrates such as granola bars, fruit etc. Like sticks, these foods
burn a little more slowly but burn steadier and longer. Logs = fat/protein such
as meat, bacon, peanut butter, butter etc. Like logs these food take longer to start
burning, but burn for a long time.
Severe Hypothermia
Core temperatures below 90 degrees produce cardiac irritability. Under these
conditions any sudden movement can cause a lethal heart rhythm. Great care must
be taken to be gentle with these victims. Do not let victim move around, warm these
people slowly. It is important to understand that when the core temperature drops below
90 degrees, the body can no longer warm itself. Applied heat is the only way
to rewarm. One good method is to put two people inside a sleeping bag. The heat
transferred from one body to the other is very effective. Skin to skin contact is best
for successful heat transfer. Building a fire is a good method also. If the
victim is conscious, warm liquids are in order. Carbohydrate foods will help to
warm the body also. Be creative and use any method that will effectively add warmth. This
person needs controlled rewarming at an advanced medical facility. If victim is
unconscious do not attempt to give fluids or food
The Unconscious Victim
Special care must be taken when treating the unconscious victim. At this
point the cardiac and respiratory systems are very delicate. Any sudden movement
may cause ventricular fibrillation of the heart, which quickly leads to death
. The victim must be warmed slowly and at a controlled rate. The introduction of too
much heat may cause serious danger. Never give food or drink to an unconscious
person. The best immediate treatment is to prevent additional heat loss, keep
the airway open, and arrange for immediate transport to a medical facility. During transport
, care must be taken not to apply too much heat too quickly.
Prevention
The best method of prevention is to be prepares for the worst conditions, no
matter what the conditions are at the time you look out of the window. Anticipate
every problem which may arise and be prepared for it. The best defense against hypothermia is to understand it. The next step is to use the layering system . Always carry
extra clothes with you. This may save your life. It's also important to keep
the body's furnace stoked with fuel. By eating easily digested food such as
carbohydrates, frequently throughout the day, the body can maintain it's normal heat production.
Keep your body hydrated. Force yourself to drink fluids on cold days. The body
can't effectively use the food it has without the proper amount of fluid in the system. Always carry emergency gear with you. And don't drink alcohol.
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