Hypothermia is a medical emergency that occurs when your body loses heat faster
than it can produce heat, causing a dangerously low body temperature.
Normal body temperature is around 98.6 Fahrenheit.
Hypothermia occurs as your body temperature falls below 95 Fahrenheit.
When your body temperature drops, your heart, nervous system and other organs
cannot work normally.
Left untreated, hypothermia can lead to complete failure of your heart
and respiratory system and eventually to death.
Hypothermia is often caused by exposure to cold weather or immersion in cold water.
Primary treatments for hypothermia are methods to warm the body back to a normal temperature.
Shivering is likely the first thing you will notice as the temperature starts to drop
because it is your body's automatic defense against cold temperature —
an attempt to warm itself.
Signs and symptoms of hypothermia include:
(Signs are what you can see.
Symptoms are what the patient tells you.)
- Slurred speech or mumbling
- Slow, shallow breathing
- Weak pulse
- Clumsiness or lack of coordination
- Drowsiness or very low energy
- Confusion or memory loss
- Loss of consciousness
- Bright red, cold skin (in infants)
Someone with hypothermia usually is not aware of his or her condition
because the symptoms often begin gradually.
Also, the confused thinking associated with hypothermia prevents self-awareness.
The confused thinking can also lead to risk-taking behavior.
Hypothermia occurs when your body loses heat faster than it produces it.
The most common causes of hypothermia are exposure to cold-weather conditions or cold water.
But prolonged exposure to any environment colder than your body can lead to hypothermia
if you are not dressed appropriately or cannot control the conditions.
Specific Conditions Leading to Hypothermia include:
- Wearing clothes that are not warm enough for weather conditions
- Staying out in the cold too long
- Being unable to get out of wet clothes or move to a warm, dry location
- Falling into the water, as in a boating accident
- Living in a house that is too cold, either from poor heating or too much air conditioning
How Your Body Loses Heat
The mechanisms of heat loss from your body include the following:
- Radiated heat
Most heat loss is due to heat radiated from unprotected surfaces of your body.
- Direct contact
If you are in direct contact with something very cold, such as cold water or the cold ground,
heat is conducted away from your body.
Because water is very good at transferring heat from your body, body heat is lost much faster
in cold water than in cold air.
Similarly, heat loss from your body is much faster if your clothes are wet,
as when you are caught out in the rain.
Wind removes body heat by carrying away the thin layer of warm air at the surface of your skin.
A wind chill factor is important in causing heat loss.
Risk factors for hypothermia include:
Your tolerance for cold diminishes when you are fatigued.
- Older age
The body's ability to regulate temperature and to sense cold may lessen with age.
Some older adults may not be able to communicate when they are cold
or to move to a warm location if they do feel cold.
- Very young age
Children lose heat faster than adults do.
Children may also ignore the cold because they are having too much fun to think about it.
They may not have the judgment to dress properly in cold weather or to get out of the cold
when they should.
- Mental problems
People with a mental illness, dementia or other conditions that interfere with judgment
may not dress appropriately for the weather or understand the risk of cold weather.
People with dementia may wander from home or get lost easily, making them more likely
to be stranded outside in cold or wet weather.
- Alcohol and drug use
Alcohol may make your body feel warm inside, but it causes your blood vessels to expand,
resulting in more rapid heat loss from the surface of your skin.
The body's natural shivering response is diminished in people who have been drinking alcohol.
In addition, the use of alcohol or recreational drugs can affect your judgment about the need
to get inside or wear warm clothes in cold-weather conditions.
If a person is intoxicated and passes out in cold weather, he or she is likely to develop hypothermia.
- Certain medical conditions
Some health disorders affect your body's ability to regulate body temperature.
Examples include an underactive thyroid (hypothyroidism), poor nutrition or anorexia nervosa,
diabetes, stroke, severe arthritis, Parkinson's disease, trauma, and spinal cord injuries.
Some drugs can change the body's ability to regulate its temperature.
Examples include certain antidepressants, antipsychotics, narcotic pain medications and sedatives.
People who develop hypothermia because of exposure to cold weather or cold water
are also vulnerable to other cold-related injuries, including:
-- Freezing of body tissues (frostbite)
- Decay and death of tissue resulting from an interruption in blood flow (gangrene)
- Staying warm in cold weather
Before you or your children step out into cold air, remember the advice that follows
with the simple acronym COLD — cover, overexertion, layers, dry.
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.
Avoid activities that would cause you to sweat a lot.
The combination of wet clothing and cold weather can cause you to lose body heat more quickly.
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 body heat better than cotton does.
Stay as dry as possible.
Get out of wet clothing as soon as possible.
Be especially careful to keep your hands and feet dry, as it is easy for snow
to get into mittens and boots.
Keeping Children Safe from the Cold
To help prevent hypothermia when children are outside in the winter -
- Dress infants and young children in one more layer than an adult would wear
in the same conditions.
- Bring children indoors if they start shivering - that is the first sign that hypothermia is starting.
- Have children come inside frequently to warm themselves when they are playing outside.
- Do not let babies sleep in a cold room.
Winter Car Safety
- Whenever you're traveling during bad weather, be sure someone knows
where you are headed and at what time you are expected to arrive.
That way, if you get into trouble on your way, emergency responders
will know where to look for your car.
- It is also a good idea to keep emergency supplies in your car in case you get stranded.
Supplies may include several blankets, matches, candles, a clean can where you can melt snow
into drinking water, a first-aid kit, dry or canned food, a can opener, tow rope, booster cables,
compass, and a bag of sand or kitty litter to spread for traction if you are stuck in the snow.
- If possible, travel with a cellphone.
- If you are stranded, put everything you need in the car with you,
huddle together and stay covered.
- Run the car for 10 minutes each hour to warm it up.
Make sure a window is slightly open and the exhaust pipe is not covered with snow
while the engine is running.
This could create carbon monoxide buildup.
To avoid alcohol-related risks of hypothermia, don't drink alcohol -
- If you are going to be outside in cold weather
- If you are boating
- Before going to bed on cold nights
Cold Water Safety
Water does not have to be extremely cold to cause hypothermia.
Any water that is colder than normal body temperature causes heat loss.
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 enabling you to float
without using energy and by providing some insulation.
Keep a whistle attached to your life jacket to signal for help.
- Get out of the water if possible
Get out of the water as much as possible, such as climbing onto a capsized boat
or grabbing onto a floating object.
- Do not attempt to swim unless you are close to safety
Unless a boat, another person or a life jacket is close by, stay put.
Swimming will use up energy and may shorten survival time.
- Position your body to minimize heat loss
Use a body position known as the heat escape lessening posture (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 are 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 have fallen into cold water with other people, keep warm by facing each other in a tight circle.
- Do not remove your clothing
While you are in the water, do not remove clothing because it helps to insulate you from the water.
Buckle, button and zip up your clothes.
Cover your head if possible.
Remove clothing only after you are safely out of the water and can take measures
to get dry and warm.
Help for people most at risk
For people most at risk of hypothermia -
infants, older adults, people who have mental or physical problems, and people who are homeless -
community outreach programs and social support services can be of great help.
If you are at risk or know someone at risk, contact your local public health office
for available services, such as the following -
- Assistance for paying heating bills
- Check-in services to see if you and your home are warm enough during cold weather
- Homeless shelters
- Community warming centers, safe and warm daytime locations where you can go
during cold weather