|
Hypothermia
Unlike other warm-blooded animals that have
a layer of hair or blubber to keep them warm, you need an extra layer of
clothing to keep you warm when it's cold outside. Without that extra layer of
clothing, more heat escapes from your body than your body can produce. If too
much heat escapes, the result is hypothermia. Exposure to cold water and certain
medical conditions also can cause hypothermia.
Hypothermia occurs when your body's control
mechanisms fail to maintain a normal body temperature. Signs and symptoms that
may develop include gradual loss of mental and physical abilities. Severe
hypothermia can lead to death.
For most Americans, hypothermia isn't a
serious risk. Still, each year nearly 700 people in the United States die of
hypothermia. In addition to prolonged exposure to cold temperatures, factors
that commonly increase your risk of hypothermia include advanced or very young
age, substance abuse, impaired mental status and immersion in cold water.
When you're outdoors enjoying such
activities as camping, hunting, fishing, boating and skiing, be aware of weather
conditions and whether you or others with you are wet and cold. The best
approach to being cold and wet is to move indoors and get warm and dry early —
before you develop hypothermia.
Signs and symptoms
Hypothermia usually comes on gradually.
Often, people aren't aware that they need medical attention. Common signs to
look for are shivering, which is your body's attempt to generate heat through
muscle activity, and the "-umbles" — stumbles, mumbles, fumbles and
grumbles. These behaviors may be a result of changes in consciousness and motor
coordination caused by hypothermia.
Other signs and symptoms may include:
 | Slurred speech
| Abnormally slow rate of breathing
| Cold, pale skin
| Fatigue, lethargy or apathy |
| | |
The severity of hypothermia can vary,
depending on how low your core body temperature goes. Severe hypothermia will
eventually lead to cardiac and respiratory failure, then death.
Causes
Your normal core body temperature is
usually right around 98.6 F. In hypothermia, your body fails to maintain a
normal temperature. An internal body temperature of 95 F or lower signals
hypothermia.
The cause of hypothermia usually is
extended exposure to cold temperatures or a cool, damp environment. Other
contributing causes include inadequate clothing and neglecting to adequately
cover your extremities, particularly your head — a disproportionate amount of
heat is lost through your head.
Hypothermia can happen not just in cold
winter weather, when there are low temperatures or low wind chill factors, but
under more mild conditions as well. A rain shower that soaks you to the skin on
a cool day can lead to hypothermia if you don't move inside to warm up and dry
off. If you stay outside, evaporation of the water from your skin further cools
your body, dropping your internal temperature. A wind blowing over the wet parts
of your body greatly increases evaporation and cooling.
An accidental fall into cold water also may
lead to hypothermia. Hypothermia may develop within minutes of being exposed to
cold water or it may take several hours, depending on the water temperature.
Water doesn't have to be icy cold to cause hypothermia. Your body loses heat
more quickly in water than in air. Any water temperature lower than body
temperature causes your body to lose some heat.
Risk factors
Being in extreme cold, wearing wet clothes
— especially in the presence of wind — and being in cold water can all play
a part in increasing your chances of hypothermia. People who are elderly, very
young, mentally impaired, intoxicated or who have certain health issues are
especially vulnerable.
| Advanced
age. People age 65 and older are especially vulnerable because they
may have other illnesses or take medications that can interfere with the
body's ability to regulate temperature.
| Very young
age. Children usually lose heat faster than adults do. Children
have a larger head-to-body ratio than adults do, making them more prone to
heat loss through the head. Children may also ignore the cold because
they're having too much fun to think about it. And they may not have the
judgment to dress properly in cold weather or to get out of the cold when
they feel cold. Infants may have a special problem with the cold because
they have less efficient mechanisms for generating heat.
| Mental
impairment. Individuals who have Alzheimer's disease or another
illness that causes mental impairment may not be aware of the risks of being
out in the cold. Wandering away from home is not uncommon among people with
Alzheimer's, and many are unable to find their way back on their own,
leaving them stranded and vulnerable to the weather.
| Alcohol and
drug use. Alcohol may make your body feel warm inside, but it
lowers your body's ability to retain heat. Both alcohol and drugs such as
marijuana can keep your blood vessels dilated, restrict your shivering
response, impair your judgment and alter your awareness of weather
conditions.
| Certain
medical conditions. Some health disorders affect the body's ability
to respond to cold or to produce heat. Examples include untreated
underactive thyroid (hypothyroidism), stroke, severe arthritis, Parkinson's
disease, trauma, spinal cord injuries, burns, blood vessel or nerve
disorders that affect sensation in your extremities (for example, peripheral
neuropathy in people with diabetes), dehydration and any condition that
limits activity or restrains the normal flow of blood. Older adults are more
likely to have one or more of these risk factors.
| Water
conditions. Factors contributing to your risk of hypothermia in
cold water include the temperature of the water and the length of time you
spend in it. Rescue time is crucial when a person accidentally falls into
cold water. Chances of survival are affected by how cold the water is: The
colder the water, the less the chance of survival. |
| | | | |
| Water temperature |
Time until exhaustion
or unconsciousness |
Expected time of
survival in the water |
| Under 32 F (icy waters) |
Less than 15 minutes |
Less than 15 to 45 minutes |
| 32.5 to 40 F (Lake Superior in
spring) |
15 to 30 minutes |
30 to 90 minutes |
| 40 to 50 F (Maine coastal waters
in spring) |
30 to 60 minutes |
1 to 3 hours |
| 50 to 60 F (Central Pacific
coastal waters year-round) |
1 to 2 hours |
1 to 6 hours |
| 60 to 70 F (Gulf of Mexico in
winter) |
2 to 7 hours |
2 to 40 hours |
| 70 to 80 F (Gulf of Mexico in
spring and fall) |
3 to 12 hours |
3 hours to indefinite |
| More than 80 F (Key West coastal
waters in summer) |
Indefinite |
Indefinite |
Source: United States
Search and Rescue Task Force
When to seek
medical advice
The signs and symptoms of the person
suffering from exposure to the cold are the strongest indications of
hypothermia. Seek immediate medical care for any person who has been exposed to
cold air or water and who is shivering, appears disoriented, shows a lack of
coordination, has cold and pale skin, appears tired, and is slurring speech. Try
to keep the person warm and dry, preferably indoors or at least out of the wind,
until help arrives.
Complications
Complications depend on how low your body
temperature falls. If you're in water, you may lose consciousness and drown
before your temperature drops low enough to cause death by hypothermia. Other
complications may include:
| Frostbite
| Loss of limbs
| Coma |
| |
The lower your core body temperature, the
greater your chance of complications and permanent damage.
Treatment
Seek immediate medical attention for anyone
who appears to have hypothermia. Until medical help is available, follow these
guidelines for caring for someone with hypothermia.
What to do
| Move the
person out of the cold. Preventing additional heat loss is crucial.
If you're unable to move the person out of the cold, shield the person from
the cold and wind as best you can.
| Remove wet
clothing. If the person is wearing wet clothing, remove it and
replace it with a dry covering. Cover the person's head. Try not to move the
person too much. Cut away clothing if you need to.
| Insulate the
person's body from the cold ground. Lay the person faceup on a
blanket or other warm surface.
| Monitor
breathing. A person with severe hypothermia may appear unconscious,
with no apparent signs of a pulse or breathing. If the person's breathing
has stopped or appears dangerously low or shallow, begin cardiopulmonary
resuscitation (CPR) immediately if you're trained.
| Share body
heat. To warm the person's body, remove your clothing and lie next
to the person, making skin-to-skin contact. Then cover both bodies with a
blanket.
| Provide warm
beverages. If the affected person is alert and is able to swallow,
have the person drink a warm, nonalcoholic beverage to help warm the body. |
| | | | |
What not to do
| Don't apply
direct heat. Don't use hot water, a heating pad or a heating lamp
to warm the victim. Instead, apply warm compresses to the neck, chest wall
and groin. Don't attempt to warm the arms and legs. Heat applied to the arms
and legs forces cold blood back toward the heart, lungs and brain, causing
the core body temperature to drop. This can be fatal.
| Don't
massage or rub the person. Handle people with hypothermia gently
because they're at risk of cardiac arrest.
| Don't
provide alcoholic beverages. Alcohol lowers the body's ability to
retain heat. |
| |
What a doctor may do
A doctor will be able to take steps to warm the body from the inside
out, if necessary. One method may involve giving the person warm fluids
intravenously. In severe cases of hypothermia, hemodialysis may restore normal
body temperatures quickly. Hemodialysis is a medical procedure that removes
extra fluid, chemicals and wastes from the blood by filtering the blood through
an artificial kidney. It's often used in people with kidney failure. In a
hypothermia situation, the blood is removed purely to warm it rapidly outside
the body and then have it returned to the body.
Prevention
For people most at risk of hypothermia —
those who are older, have mental or physical impairments or who are homeless —
community outreach programs and medical and social support services can be of
great help. Identifying and checking in on vulnerable people and groups,
preventing prolonged exposure to the cold and ensuring adequate heating are ways
to help reduce the number of hypothermia deaths. Monitoring bracelets may
provide assistance for people who have a tendency to wander from home. In
addition, public health prevention strategies can help educate people about the
dangers of prolonged exposure to cold.
Avoid excessive alcohol consumption and the
use of illegal substances, because these may increase your risk of hypothermia.
Also, don't drink alcohol and operate a boat or other watercraft. Alcohol can
impair your ability to navigate the waters, increasing your risk of an accident
and of falling into cold water.
Staying healthy in cold weather
Before you or your children step out into cold air, remember the advice that
follows with the simple acronym COLD:
| C for
cover. Wear a hat or other protective covering to prevent body heat
from escaping from your head, face and neck. Cover your hands with mittens
instead of gloves. Mittens are more effective than gloves are because
mittens keep your fingers in closer contact with one another.
| O for
overexertion. Avoid activities that would cause you to sweat a lot.
The combination of wet clothing and cold weather can give you chills.
| L for
layers. Wear loose-fitting, layered, lightweight clothing. Outer
clothing made of tightly woven, water-repellent material is best for wind
protection. Wool, silk or polypropylene inner layers hold more body heat
than cotton does.
| D for
dry. Stay as dry as possible. In the winter, pay special attention
to places where snow can enter, such as in loose mittens or snow boots. |
| | |
During cold-weather months, keep emergency
supplies in your car in case you get stranded. Supplies may include several
blankets, matches, candles and some foodstuffs, such as granola bars or
crackers. A cell phone also can come in handy. If your car is stuck in a snow-bank,
be careful about leaving the engine running, as infiltration of carbon monoxide
inside the car may pose a silent danger.
Cold-water cautions
Water doesn't have to be extremely cold to cause hypothermia. Any water
that's colder than body temperature causes heat loss. Water that's colder than
70 F can quickly begin to cause hypothermia. The following tips may increase
your survival time in cold water, if you accidentally fall in:
| Wear a life
jacket. If you plan to ride in a watercraft, wear a life jacket. A
life jacket can help you stay alive longer in cold water by allowing you to
float without using energy and providing some insulation.
| Don't panic.
If you're unable to swim to safety, stay calm. Unnecessary movements require
you to exert extra energy and lose body heat.
| Position
your body to minimize heat loss. Use a body position known as the
heat escape lessening position (HELP) to reduce heat loss while you wait for
assistance. Hold your knees to your chest to protect the trunk of your body.
If you're wearing a life jacket that turns your face down in this position,
bring your legs tightly together, your arms to your sides and your head
back.
| Huddle with
others. If you've fallen into cold water with other people, keep
warm by facing each other in a tight circle.
| Don't remove
your clothing. Buckle, button and zip up your clothes. Cover your
head if you have a hood. The layer of water between your clothing and your
body will be warmed and help insulate you.
| Don't
attempt to swim unless you're close to safety. Unless a boat,
another person or a life jacket is close by, stay put. Swimming expends
extra energy, lowers body temperature and can shorten survival time. |
| | | | |
By Mayo
Clinic staff
Home TOC
Copyright © 1999 Yoga A Way Of Life
Last modified: August 19, 2006
|
