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Hypothermia
How to Avoid Hypothermia
BY CRISTEN CONGER
The
human body is somewhat like that perfect bowl of porridge in "Goldilocks
and the Three Bears." It's not too hot, not too cold, but just right.
Our
bodies maintain internal body temperatures that allow our insides to keep
on cooking without burning up or slowing down -- usually around 98.6 degrees
Fahrenheit (37 degrees Celsius). There's even a part of our brain called
the hypothalamus that regulates this internal heat to keep
everything running smoothly.
But
when that core temperature of major organs drops down to 95 degrees or lower,
it is called hypothermia. Just like when you have a high fever,
hypothermia can slow your body and possibly lead to death.
When
it comes to our bodies, a lot depends on heat. Heat is the byproduct of
biochemical reactions within our bodies. The food and beverages we consume are
just like the wood and kindling that make a fire. Our bodies gain energy from
food, and that energy pumps our hearts, grows our hair and helps our digestive
system break that food down into usable units. This process is
called metabolism.
Think
about all of the internal processes that take place when you run. It requires
energy to move so many parts of your body at the same time. When all those
parts crank up, we burn up energy, producing heat.
In
the cold, our bodies strive to retain as much heat, or energy, as possible. In
many parts of the body, blood vessels in our skin tissue constrict,
or tighten up. This tightening helps keeps blood away from the cold outer layer
of the body and helps circulate warmer blood to our core areas. This tightening
is also why you may feel stiff after being in the cold for a long time.
However,
areas with large blood vessels, particularly around the head, neck, chest and
groin, are more susceptible to heat loss because those blood vessels don't
constrict as effectively as the smaller ones near the skin. That's why proper
winter attire includes a hat, scarf and coat.
With
all of these internal actions and reactions taking place within the body, what
can we do to protect our core temperature and defend ourselves from
hypothermia? We'll answer those questions, and explain how hypothermia develops
on the next page.
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How Hypothermia Happens
While
it is important to keep our bodies properly warm, it is equally important for
us to be able to cool down. But in certain environmental conditions our bodies
cool down too much. Our temperatures drop too far when they dip into
hypothermic internal temperatures of 95 degrees and lower.
There
are four main ways that our bodies give off heat and cool themselves:
conduction, convection, radiation and evaporation. Each of these processes
helps us sustain healthy internal temperatures. They also give us a better
understanding of how hypothermia happens.
We
constantly release heat in the form of radiation. In the same way
the sun emits heat down on us as we bask on a beach, our bodies exude heat
as a natural by-product of our metabolism.
When
you hold a chocolate chip in your hand for a few minutes, it will likely
begin to melt. This process is called conduction. It occurs when
our bodies come into contact with something that has a lower temperature. The
body gives away heat to that other object.
If
we give away heat to something in motion, however, convection takes
place. When wind puts air particles in motion, they take away heat as they hit
our bodies and move away. That's why a wind chill can make it feel colder
outside than the true temperature.
Finally,
when we work up a sweat, we experience evaporation, when water on
our skin transforms into a gas.
Our
blood vessels also play an integral role in heating and cooling. They
expand or constrict to free or restrict blood flow to our skin tissue.
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When our
metabolism heats up our insides, it warms our blood as well.
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To control that
building heat, blood vessels at our skin dilate -- like our pupils in low light
-- to circulate more of that warmed blood toward the skin's surface and allow
the body to release heat.
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This opening of the blood vessels is called vasodilatation.
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Alcohol and
tobacco both cause vasodilatation, which is why both substances can give you
the sensation of warmth, even though your core temperature is colder.
Since
our bodies naturally give away heat to colder, active particles, air particles
in wind and water particles can accelerate that effect. Water is denser than
air, so it absorbs more heat. That's why water can steal up to 32 times more
heat from our bodies than air can [source: U.S. Search & Rescue Task Force].
Even
when we get caught in a rain shower, it can lead to hypothermia because of how
quickly water cools us.
To
combat this rapid cooling, we shiver. Think about being outside on a winter day
and how, as the cold hits, you instinctively bring in your arms and legs and
tighten those muscles.
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Shivering is our bodies' way of generating heat by
exciting our muscles. Our blood vessels also constrict to limit the amount of
blood travelling toward our skin.
When
someone's re-warming reactions, like shivering, aren't enough to overcome the
cooling process, hypothermia can set in. Look for several important signs
indicating the different stages of hypothermia.
· Mild Hypothermia: shivering, goose bumps,
difficulty with complex motor skills
· Moderate Hypothermia: violent shivering,
sluggish, speech problems, difficulty with fine motor skills
· Severe Hypothermia: rigid muscles, dazed,
shivering has stopped, blue skin, erratic heart beat, unconscious
If
severe hypothermia sets in, complications can include coma and even death.
Other cold weather injuries are also associated with hypothermia, such as
frostbite, chilblains (ulcers on the toes) and trench foot (a foot infection).
Now
that we understand how our bodies can cool too rapidly and cause hypothermia,
we'll learn ways to prevent that from happening.
Although
many cases of hypothermia arise from being outdoors in cold weather or water,
it can happen at home as well. During the winter, stay aware of how cold your
house is.
.
People have become hypothermic in houses that were around 60 degrees
Fahrenheit (15.5 degrees Celsius). Power outages in the winter can also send
temperatures plunging, making it essential to wrap up and keep warm.
People
are most susceptible to hypothermia outdoors. Whether you get stranded in a
snowy field or fall into a chilly lake, you can become hypothermic quickly. So
you should be prepared.
First,
properly fuel yourself. Remember that the body requires food and nutrients
to make heat, so going out without eating enough or being dehydrated can put
you at risk. Carbohydrates, proteins and fats are the prime food groups to
munch on since they provide both short- and long-term energy supplies.
Sweet,
non-caffeinated beverages are also appropriate, since the sugar will boost
energy quickly. Caffeinated drinks hinder your body from absorbing water,
promoting dehydration.
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Alcohol and smoking should also be completely
avoided. Both of these make your blood vessels expand, which is called vasodilatation,
and your body lets off heat faster.
In
wintery weather, it is also essential that you dress for the C.O.L.D.:
· Cover: Since we lose so much heat from
our head, we should wear scarves and hats over head, neck and face. Mittens are
also better protectors than gloves because they trap more heat.
· Overexertion: Be careful to not
overwork yourself in the cold. If you deplete your body's energy reserves, you
will have a harder time warming back up when you get cold.
· Layer: Wear loose clothing in multiple
layers. To prevent yourself from sweating and cooling down too much, remove a
layer if you get hot. Looser clothing retains heat well, but your sleeves
should fit snugly at the wrists. Thermal underwear can also be an effective
base layer to keep heat close to your body.
· Dry: Choose insulating fabrics such as
wool, silk and polypropylene, rather than absorbent cotton. If your clothes get
wet, remove them as soon as possible since water cools the body much faster
than cold air. [source: Mayo
Clinic]
Even
in warmer weather, water-related accidents can lead to hypothermia. For that
reason, wear a lifejacket while on boats and do not drink alcohol while on
boats or around water.
Freezing
cold water can also render someone unconscious in less than 15 minutes. It's
critical to preserve body heat. People who have fallen in cold water should
resist the automatic urge to flail or tread water. And unless the shore is less
than 200 yards away, people also shouldn't try to swim to land [source: Piantadosi].
Doing
so only drains precious energy stores. Instead, if alone in the water, you
should pull your knees into your chest with your hands at your sides. If a
group of people are in the water, they should huddle together to share body
heat.
In
the next section, we'll learn what to do if someone exhibits signs of
hypothermia. Can you help restore that person to their normal temperature?
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How to Avoid Death from Hypothermia
Nearly
700 people in the United States die each year from hypothermia [source: Mayo Clinic].
Hypothermia
is a silent killer because once your body temperature drops below 95 degrees,
you lose awareness of the cold and become disoriented because less oxygen
reaches the brain. For that reason, take special precautions if you're alone in
the cold. You may not be aware that your body is in peril.
Groups
of people should look after each other for the signs of hypothermia discussed
in the previous section. If someone does appear hypothermic, there are a number
of things that you can do to prevent that person from dying. In mild to
moderate cases, the body can re-warm at a rate of 3.6 degrees per hour.
To
start that warming process, first move into shelter. If there is nowhere to go
indoors, at least move the person out of the wind, since wind can speed up
hypothermia. Remove any wet clothing and replace them with dry blankets or even
newspaper.
For
people with mild or moderate hypothermia, some food and beverages may be
helpful. Warm, sweet liquids, such as diluted gelatin mix or hot chocolate will
give the body quick energy boosts to help it produce heat. Proteins, fats and carbohydrates
in the form of trail mix and granola can also stimulate the metabolism. Do not
give them alcohol or caffeine.
In
more severe cases, getting a person out of any wet clothes and into a
hypothermic wrap is essential. There should be several layers of insulation
between the wrap and the cold ground. A hypothermic wrap covers
every part of the body with as few open spaces as possible. A sleeping bag or
multiple blankets can serve as hypothermic wraps, as long as the person is
completely protected from the cold.
Additionally,
extra clothing or blankets should be applied to the neck, groin, armpits and
chest to protect major arteries. Sharing body heat by removing your clothes and
getting into the wrap with the person may also prove beneficial, except in very
severe cases. Also, do not apply heat directly to the skin or give the person a
massage because it can circulate the colder blood near the skin to the
core, shocking the body.
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Hypothermic
wraps cover people's bodies entirely while being insulated from cold ground.
CPR is
another option if a hypothermic person's skin has turned blue, and you can't
feel a pulse. But only do this if you are properly trained. If you stimulate
the body too much with CPR, it can overexcite the heart and lead to cardiac
arrest.
If
possible, call 911 to get someone with severe hypothermia to a
hospital. A doctor may hook up a person with hypothermia to an IV to put
warming fluids directly into the body. He or she may also perform a procedure
called hemodialysis, which takes the patient's blood out of the
body, runs it through a warming mechanism, and returns it.
For
more information on protecting against cold weather calamity, go to the links
on the next page.
HYPOTHERMIA RISK GROUPS
Infants and the
elderly are the most at risk for developing hypothermia. Babies do not preserve
body heat as well as adults, and the elderly may not have a high enough
metabolism to stay warm. For both, it is important that their bedrooms not be
too cold and that they are regularly monitored during the winter.
About Cristen
Conger
Raised on a steady diet of Technicolor musicals and
library books, Cristen Conger always wanted to be a writer when she grew up.
While working toward her journalism degree at the University of Georgia, she
learned to avoid starry-eyed statements about childhood dreams and stick to
hard facts. After graduating, Cristen decided she'd spent enough time chasing
down REM band members in Athens and hitched up the road to Atlanta where she
jumped on board with the award-winning web site HowStuffWorks.com.
As a writer and blogger for HowStuffWorks and a
contributing writer for Discovery News, Cristen specializes in technology and the science of
everyday living. Her articles have featured on Huffington Post, ABC Science and MSNBC.com.
She also co-hosts the popular Stuff Mom Never Told You podcast, which explores
gender issues such as relationships, careers and women's history. A graduate of
University of Georgia, where she majored in journalism, Cristen reads, writes,
runs and dabbles in improv comedy.
