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We thought that we would bring you an informative
article concerning the dangers of the cold. For many, winter
means playing outdoors in the snow, tackling the slopes on a
weekend ski trip, participating in an adventurous mountain climb,
ice skating on a frozen lake, and many other winter-related activities.
However, while all of these activities
have one obvious thing in common, "THE COLD", they
also all have a more cynical and underlying similarity. This
is the ability to victimize those who are just trying to have
a good time through an extremely dangerous and very common enemy
known as "HYPOTHERMIA".
This first article, in a series of two,
will attempt to familiarize the reader with a clear definition
of what hypothermia really is, and will discuss its various causes
and symptoms.
What is "hypothermia"?
First some of the things it isn't. It isn't
"feeling cold". It isn't that feeling you get when
you play in the snow and your fingers are getting stiff. That
kind of cold is much more superficial and can be easily controlled
by the body when you stop your exposure. In fact it isn't even
necessary for the temperatures to be at or below freezing for
hypothermia to take place. There have been many instances of
hypothermic death that took place in temperatures over 50 degrees
f. What is necessary in order for Hypothermia to occur is that
the body be unable to maintain it's operating temperature in
the face of whatever heat loss process is in operation. Hypothermia
is heat loss at the body core, and it results from exposure to
cold with the addition of other heat loss mechanisms.
Typically we can say that four elements
are present in each case of hypothermia, and without most of
those four elements it almost never happens.
The four elements leading to hypothermia
are: Cold, Wind, Wetness, and most important, a likely victim.
It should be obvious that many of us have
been exposed to cold ,wind and wetness without ever having experienced
Hypothermia. Naturally this is because we were prepared for the
conditions we were exposed to, which leads us to another representation
of hypothermia as "The killer of the unprepared".
One of the most important goals of this
article will be to give you the information you need to remove
yourself from the ranks of the "unprepared". This will
be easier if you understand more about the clinical aspects of
hypothermia as well as the simple and effective methods we can
use to survive the sometimes hostile forces of cold. In order
to be prepared we need to examine the four elements leading to
hypothermia a bit more closely.
COLD:
The second law of thermodynamics states
in effect: "Heat must pass from the warmer body to the colder
body." This simply means that when you expose yourself to
the cold, you lose heat. The heat you are losing is probably
heat that was generated by your body. Your body has a maximum
limit to the amount of heat that it can produce, when the limit
is reached, it can produce heat no faster. If heat is taken away
faster than it is produced, the body will begin to cool.
You are already familiar with some of the
effects of cold on the human body. For instance you know that
as the body begins to lose heat faster than it is producing the
heat it reacts by trying to reduce the rate of heat loss. This
reduction in heat loss is brought about by a restricting the
circulation in the surface of the skin. When this happens you
begin to feel the cold. Later, with continued heat loss, the
body will show other symptoms. Blood flow to the extremities
will be reduced, giving you a sort of numbness and a reduction
in coordination, strength and control, "I'm so cold my fingers
are stiff." is an example of that closing down of blood
to the muscles in the fingers. Continued exposure closes down
more systems, the blood temperature throughout the body is reduced
and the brain is affected. It is remarkable how sensitive the
brain is to these temperature drops. A reduction of 20 Degrees
f. at the brain will kill you while a drop of over 50 degrees
(from normal) in !
the hands and feet will cause discomfort but no permanent damage.
WIND:
Wind increases the cooling effect of cold
or wetness. This occurs when the moving air encounters the thin
layer of warm air clinging to your body. The moving air strips
away the warm insulating layer and the body tries to generate
another layer of warm air. As this new layer is removed the body
transfers more heat to warm more air etc. This effect is known
as this wind chill effect. Wind chill accounts for a very high
percentage of deaths due to hypothermia. It is easy to overlook
this factor and to wander unprepared for wind chill into what
appears to be cold weather.
It was mentioned that there have been cases
where persons have died of hypothermia in temperatures around
50 degrees F. Part of the reason can be wind chill, take for
instance an air temperature of 50 degrees, add the mind chilling
effect of a 40 MPH wind and we have an effective temperature
of 26 degrees. Many snow skiers have felt this effect when they
find that although the temperature outside is low, in the sun
it feels comfortable to the skin. Come the clouds, and a fast
downhill run and the cold wind will put frost on the soul.
Another point to be made is that for the
wind to assist the cooling it is only necessary for the air to
be moving relative to the warm body. The same wind chill effect
applies when the body is moving rapidly through the air. A driver
on a motorcycle for instance, moving at 40 MPH on a windless
day will experience the same chilling effect as a stationary
person in a 40 MPH wind. Imagine if you will, what would happen
to a motorcyclist who is driving along, cold because of the wind
chill, and finds stiff fingers operating clutch and brake controls.
Motorcyclists are frequent victims of hypothermia. They do not
progress through the stages of hypothermia to actual death while
astride their bikes, rather they simply lose some of their awareness,
the control of their machines and die of something else. like
compression during a collision.
If a person is adequately protected from
the cooling effect of wind, there is a very much reduced chance
of hypothermia. This person is Prepared for wind.
WETNESS:
Wetness increases heat loss through evaporation.
Think about the body for a moment. You already know what happens
when you get very hot. You perspire. Your body doesn't do that
simply because it likes to discharge water and increase your
odor. Sweating is an adaptive process that enhances cooling.
You know how good it feels to stand in front of a fan, or in
the wind, on hot days, Cool right? Water increases the cooling
effect of wind and vice versa, This water can come from any source,
It may be the result of rain, immersion, perspiration, or from
any other source. When the body is wet it loses heat much more
rapidly.
Much more rapidly is something of an understatement.
Studies suggest that water may conduct heat up to 240 times faster
than dry air. It has been proven that survival times for an unprotected
human in 35 degree water is listed in minutes. Heat is ripped
from the body so rapidly that it loses its strength, coordination
and the victim drowns.
If you've got a waterproof covering of
some sort and you use it to stay dry during a storm, then you
are prepared for wetness. A suggestion in this vein. It is often
inconvenient to carry a poncho or a tube tent when you take a
short day hike. However, be prepared anyway. The lightest serviceable
covering I know of is the large, heavy duty trash bag.
To use it simply cut a 9" slit in
the bottom, pull it over your body until your head sticks through
the slit, and stay dry. It will protect you from wind and wetness.
THE LIKELY VICTIM:
The likely victim is the unprepared victim,
If you know some of the factors that will contribute to your
heat loss you can be better prepared. if you take some realistic
steps you can remove yourself from the category altogether. simple
preparations such as the one mentioned with the trash bag will
improve your chances for survival. Think about it, How much does
that trash bag cost? How heavy and awkward is it? It actually
fits into your back pocket with only a small bulge.
Trash bags and wind aside, there is another
part to being the likely victim. Panic and hysteria. Many persons
who find themselves in a survival situation do not know the techniques
necessary for survival. They may react mindlessly and try to
travel vast distances with limited energy resources. This activity
not only depletes their reserves, it often brings on other parts
of the hypothermia problem. Their thoughtless actions result
in sweat, exposure to the wind, and depletes their ability to
ward off even minor environmental temperature changes. They are
what can be called the "emotionally unprepared victims".
The problem is neatly described by an old saying. "In panic,
a person can run for minutes, crawl for hours, and then lie down
from exhaustion for eternity..."
The likely victim then can include someone
who is faced with the heat loss mechanisms of cold, wind and
wetness to a minor degree. But with an emotional instability
capable of magnifying the effects of simple heat loss much as
both wind and wetness magnify the effects of the cold. All of
this is part of the reason for developing a Positive Mental Attitude.
Understanding the problem is half of the solution, doing something
about it is the other half.
The Symptoms of Hypothermia
Once you know that hypothermia exists,
and what conditions are likely to precede the problem, it becomes
necessary to know how to recognize the symptoms. That old saw
"Forewarned is Forearmed." fits nicely here since merely
recognizing the symptoms can put you on the alert and set into
motion the actions necessary to save a life. It is also important
to realize that recognizing the symptoms of Hypothermia in yourself
is sometimes difficult for reasons soon to be explained.
Experiments performed by various public
and private institutions have tended to yield similar results.
In most of these experiments Human beings were put through exposure
to low temperatures while their blood pressure, temperature,
reaction times, strength and motor skills were monitored. The
tests have shown dramatic losses in the thinking abilities of
the subjects while simple motor activities became nearly impossible.
Total incapacitation almost always occurred before loss of consciousness.
During the course of the experiments certain
facts became clear. Among those was an agreement on specific
temperature ranges and symptoms, indicating the stages of hypothermia.
In other words, researchers discovered that when the body cools
to a certain point a specific symptom develops, Continued lowering
of the temperature brings on the next set of symptoms. These
symptoms are common to most subjects experiencing the same body
core temperature. They also discovered that people have different
abilities to resist the onset of hypothermia. Where one individual
might drop into hypothermia at 50 degrees ambient, another in
similar shape and condition, might not become hypothermic until
the temperature dropped to 40 degrees.
We realize this fact is not especially
shocking as we all know that people react differently to the
same conditions. The reason it is pointed out is to indicate
that the following information, while it has internal and symptomatic
consistency, does not necessarily develop in each person at the
same external temperature.
A "Normal" healthy human, in
good condition with adequate energy reserves can maintain the
body core temperature at it's "normal" 98.6 degrees
F while exposed to ambient air temperatures of 50 degrees F.
The air of course is still and the body dry. At this point the
body is pumping out heat as fast as it can and the core temperature
is stable. Since the body heater is full on, for each degree
the environmental temperature drops, the body core temperature
will drop a corresponding degree.
Stages of Hypothermia
|
Stage of Hypothermia |
First |
Second |
Third |
|
Air Temp (F) |
47-50 |
42-46 |
37-41 |
|
Body Core Temp (F) |
96-99 |
91-95 |
86-90 |
|
Symptoms |
Uncontrollable shivering |
Violent shivering in waves, poor coordination
and stumbling |
Shivering ceases. Muscles are stiff or rigid.
Impaired thinking and judgment |
|
Stage of Hypothermia |
Fourth |
Fifth |
Sixth |
|
Air Temp (F) |
32-36 |
Below 32 |
Below 32 |
|
Body Core Temp (F) |
81-85 |
78-80 |
Below 78 |
|
Symptoms |
Rigidity continues, slowed pulse rate and
respiration. Stupor, Immobility |
Unconsciousness, most reflexes cease, heart
beat erratic, possible death |
Cardiac Fibrillation. Edema & hemorrhage
in the lungs. White foamy discharge from the lungs. Death |
While looking this over it is wise to keep
in mind the fact that the temperatures given for the "Air
temp." are approximate. Conditioning, fat accretions etc.
all play a part in setting the final symptomatic display. Even
the final temperature prior to death has been exceeded in both
directions. Persons have survived lower internal temperatures
and have died with higher ones. The symptoms however are very
commonly associated with the stages as shown.
A few points need to be made here. You
will notice that as an individual develops hypothermia the first
symptoms of "uncontrollable shivering" occur. This
is not that gentle "Brrrrr I'm cold" shiver. This is
a good strong full body shiver of the tooth shattering variety.
The victim feels cold inside. This shivering stage is the attempt
by the body to generate heat with muscular activity of the involuntary
variety. When the temperature continues to drop, the mechanisms
in control of the shivering reduce their activity and the body
reduces the flow of blood to most large muscle groups not necessary
for survival. With a reduction in shivering comes the beginning
of the end for reasoned action by the victim Also keep in mind
the appearance of the victim to an observer. First the victim
is shivering hard, then there is less shivering. This gives the
impression that the victim is warming. After all, there is less
shivering. As you read the symptoms again keep this fact in mind.
You !
may not be able to tell immediately if the victim is warming
or cooling.
When the shivering ceases during the third
stage hypothermia, death is at the doorstep. A lone hypothermic
has little chance of survival unless fortune provides some external
source of heat as well as a reduction in heat loss. The wind
stops, the sun drives the clouds apart, a bush bursts into flame
while a cup of hot cocoa appears on the ground. Lotsa luck.
Once the victim drops into fourth stage
hypothermia it's all over but the dying. Even if a rescue is
affected there is a chance that death will still occur. Any first
aid measures that take place after the victim becomes a hypothermic
in the fourth stage, must be of an extreme sort administered
in a specific manner. Simply covering the victim may delay death
by a few minutes. Still there remains the chance of survival
if certain steps are taken immediately by the rescuer. Even then
much of the ability of the victim to survive is dependent upon
the condition and the will of that victim. Injuries and illness
lessen the likelihood of survival. Inappropriate or inadequate
treatment may hasten death. |