Health Encyclopedia

Hypothermia

Definition

Hypothermia is dangerously low body temperature, below 95°F (35°C).

Alternative Names

Low body temperature; Cold exposure

Considerations

People most likely to experience hypothermia include:

Very old or very young
Chronically ill, especially with heart or circulation problems
Malnourished
Overly tired
Under the influence of alcohol or drugs

Causes

Hypothermia occurs when more heat is lost than the body can generate. It is usually caused by extended exposure to the cold.

Common causes include:

Being outside without enough protective clothing in winter.
Falling overboard from a boat into cold water.
Wearing wet clothing in windy or cold weather.
Heavy exertion, not drinking enough fluids, or not eating enough in cold weather.

Symptoms

As people develop hypothermia, their abilities to think and move are often lost slowly. In fact, they may even be unaware that they need emergency treatment. Someone with hypothermia also is likely to have frostbite.

The symptoms include:

Drowsiness
Weakness and loss of coordination
Pale and cold skin
Confusion
Uncontrollable shivering (although at extremely low body temperatures, shivering may stop)
Slowed breathing or heart rate

Lethargy, cardiac arrest, shock, and coma can set in without prompt treatment. Hypothermia can be fatal.

First Aid

If any symptoms of hypothermia are present, especially confusion or changes in mental status, immediately call 911.
If the person is unconscious, check airway, breathing, and circulation. If necessary, begin rescue breathing or CPR. If the victim is breathing less than 6 breaths per minute, begin rescue breathing.
Take the person inside to room temperature and cover him or her with warm blankets. If going indoors is not possible, get the person out of the wind and use a blanket to provide insulation from the cold ground. Cover the person's head and neck to help retain body heat.
Once inside, remove any wet or constricting clothes and replace them with dry clothing.
Warm the person. If necessary, use your own body heat to aid the warming. Apply warm compresses to the neck, chest wall, and groin. If the person is alert and can easily swallow, give warm, sweetened, nonalcoholic fluids to aid the warming.
Stay with the person until medical help arrives.

Do Not

DO NOT assume that someone found lying motionless in the cold is already dead.
DO NOT use direct heat (such as hot water, a heating pad, or a heat lamp) to warm the person.
DO NOT give the person alcohol!

Call immediately for emergency medical assistance if

Call 911 anytime you suspect someone has hypothermia. Give first aid while awaiting emergency assistance.

Prevention

Before you spend time outside in the cold, DO NOT drink alcohol or smoke. Drink plenty of fluid and get adequate food and rest.

Wear proper clothing in cold temperatures to protect your body. These include:

Mittens (not gloves)
Wind-proof, water-resistant, many-layered clothing
Two pairs of socks (avoid cotton)
Scarf and hat that cover the ears (to avoid major heat loss through the top of your head)

Avoid:

Extremely cold temperature, especially with high winds
Wet clothes
Poor circulation, which is more likely from age, tight clothing or boots, cramped positions, fatigue, certain medications, smoking, alcohol, and diseases that affect the blood vessels (such as diabetes)

References

Danzl DF. Accidental hypothermia. In: Marx JA, Hockberger RS, Walls RM, eds. Rosen’s Emergency Medicine: Concepts and Clinical Practice. 6th ed. St. Louis, Mo: London: Mosby; 2006: chap. 138.

Review Date:6/9/2008
Reviewed By:John E. Duldner, Jr., MD, MS, Assistant Professor of Emergency Medicine Director of Research, Department of Emergency Medicine Akron General Medical Center and Northeastern Ohio Universities College of Medicine. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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