What is hypothermia?

Hypothermia refers to the condition in which the body temperature drops 4 degrees F (2 degrees C) or more below normal. Normal body temperature ranges between 97.2 degrees F (36.2 degrees C) and 99.5 degrees F (37.5 degrees C). At much lower temperatures, the metabolism (bodily functions) slows down. There is a risk of freezing to death.

How does it occur?

Hypothermia can occur when a person:

• spends a lot of time outside in cold weather, unprotected from the elements or in an unheated indoor environment

• wears cold, wet clothing for too long

• stays too long in cold water.

Hypothermia also may follow a heart attack or stroke.

Infants and the elderly are more likely to get hypothermia, and may even get it indoors. The very young and very old use up energy reserves quickly and are not as able to maintain an even temperature in cold surroundings. Others at greater risk for hypothermia are drug or alcohol abusers.

Hypothermia is more likely if an accident, for example, keeps a person from moving around or from functioning mentally. Also, certain medicines such as tranquilizers, cardiovascular drugs, sedatives, and anti-depressants may increase the risk of hypothermia.

If a person's body temperature stays at 90 degrees F (32.2 degrees C) or less for more than a few hours, body functions slow down and then stop. If the hypothermia is not treated, the person dies.

What are the symptoms?

Hypothermia occurs gradually. The symptoms of hypothermia usually progress as follows:

• pale, puffy face

• cold feet, hands, and face

• shivering (may not be present with the elderly)

• listlessness

• drowsiness

• mental confusion, irrational thinking

• apathetic, hostile, irritable attitude

• cold abdomen

• poor coordination and balance

• stilted, jerking movement

• slow, shallow breathing

• slowed or irregular heartbeat

• stiff muscles and some trembling on one side of the body

• loss of consciousness

• loss of heartbeat.

How is it diagnosed?

Diagnosis is based on the symptoms listed above. If a health care provider is present, he or she will take the person's temperature using a thermometer that reads low temperatures or test the temperature of the person's urine.

How is it treated?

The person with hypothermia needs immediate attention. First, try to get emergency medical help, especially if the person is also unconscious. Dial 911 or call an ambulance. Then try to help the person as follows:

• If the person is not breathing, start rescue breathing (CPR or artificial respiration).

• Take off cold, wet clothing.

• Wrap the person in warm blankets or other coverings. If you must remain outdoors, cover the person's head and keep him or her from direct contact with the cold ground.

• As soon as possible, move the person carefully to a warm place and begin rewarming.

Rewarming must be done slowly to prevent a rush of blood to the surface of the body away from vital organs that need blood. If rewarming cannot be done by trained medical personnel, do the following:

• Remove any damp clothes and dress the person in dry clothes or cover the person with blankets.

• Give warm liquids to drink.

• Allow the person to warm up gradually in a warm room.

• Give the person a warm (NOT hot) bath.

DO NOT do the following:

• Give the person HOT liquids to drink.

• Force the person to eat or drink anything.

• Give alcoholic beverages.

• Try to warm cold skin by rubbing or massaging.

• Cover with heavy layers of blankets.

• Allow the person to walk.

• Use hot water bottles, heating pads, or electric blankets.

A person with severe hypothermia needs to be treated in a hospital as soon as possible.

How long will the effects of hypothermia last?

The symptoms of hypothermia will last from a few hours to 10 or 12 hours, depending on the level of the body temperature, the severity of the condition, the age of the person, and the treatment used.

What can be done to prevent hypothermia?

There are a number of ways to prevent hypothermia. People who know they will be exposed to the cold should take the following precautions:

• Wear several layers of warm, loose clothing, especially headgear.

• Wear a protective waterproof and windproof outer garment.

• Keep their head and neck covered to help retain body heat.

• Stay dry.

• Do NOT drink alcoholic beverages.

• Be aware of the symptoms of hypothermia and emergency treatment for it.

• Have on hand space blankets (sheets of plastic and aluminum that help retain heat) and high-energy food in case of an emergency.

People over age 65 should take the following precautions during cold weather:

• Have someone check with them regularly during the winter. Check at least daily if it is very cold.

• Have their home properly insulated.

• Keep their living area warm (above 65 degrees F, or 18.3 degrees C).

• Wear layers of warm clothing to help keep body temperature even.

• Cover head and neck, even indoors, if they have trouble keeping warm.

• Stay dry.

• Be sure to have and use enough warm blankets.

• Practice good general health habits, such as getting plenty of rest and exercise and eating nutritious food.

• Keep a supply of nutritious food on hand that can be prepared easily.

• Eat hot meals and drink warm liquids throughout the day.

• Arrange for "meals on wheels" if they are unable to cook.

• Avoid alcoholic beverages.

• Check with their doctor to see if any medication they take regularly might increase their risk of hypothermia. (Drugs that reduce the body's ability to respond to cold include tranquilizers, cardiovascular drugs, sedatives, and antidepressants.)

• Take their temperature occasionally.

• Ask for help whenever needed from agencies such as the Visiting Nurses Association, agencies that can provide funds to help pay fuel bills, the Council on Aging, churches, or hospitals.