Hypothermia

Hypothermia occurs when the body's core temperature drops to 95 degrees F or lower. This can occur gradually through exposure to cold weather or suddenly by immersion in cold water.  About 1,000 people in the United States die from hypothermia each year.

In cold temperatures (45 degrees F or below), the evaporation of moisture from damp or wet clothing can cause the body to lose heat rapidly. Not wearing warm enough clothing can also lead to hypothermia. The elderly and extremely young are more susceptible to hypothermia than adolescents and middle-aged adults.  Thin people are more susceptible than those who are overweight or obese, and people with some chronic illnesses are more susceptible than healthy people. 

The second basic type of hypothermia is immersion. When a person is immersed in cold or cool water, the body loses heat rapidly. Depending on the water temperature, hypothermia from immersion can occur in a matter of minutes.

Symptoms

Early symptoms of hypothermia include:

• Uncontrollable shivering

• Cold, pale skin (usually beginning in the hands and feet and moving toward the trunk)

• Confusion, irritability and irrational or erratic behavior

• Slurred speech

• Memory lapses

• Fumbling, stumbling or staggering

At first, the heart rate and breathing may be faster than usual, but as the body temperature continues to drop, breathing may become abnormally slow. The person may also become tired or apathetic. The condition becomes grave when shivering stops, muscles become stiff and skin turns bluish.

First Aid

• To treat hypothermia, get the person out of the cold and remove any damp or wet clothing. Dress the person in warm, dry clothing and wrap in blankets, or put the person in a bath of warm water (unless the person is unconscious). Give warm, nonalcoholic drinks such as coffee, tea, hot cider or cocoa.

• Do not rub or massage the person. Doing so may cause cold blood from the extremities to flow back toward the heart, making it even more difficult for the body to rewarm.

• If you are in the wilderness, have someone stay with the person. Don't try to move a person with hypothermia. It is better to wait for help to come to you. If you have blankets or a sleeping bag available, wrap yourself up together with the person. Use your body heat to help warm him or her. Lying naked, or with only underwear on, will allow more body heat to reach the other person.

• Call the doctor's office for advice if the only symptoms are shivering and cold, pale skin. The doctor or nurse will be able to tell you whether a trip to a clinic or hospital is necessary. If the person develops other symptoms of hypothermia, get medical help as soon as possible, even if the person seems to have warmed up again.

• Very hypothermic people are at risk for developing fatal heart arrhythmias and require close medical monitoring.  If there are any questions about the degree of hypothermia, call 911.

Preventive Care for Hypothermia

Fortunately, hypothermia can be prevented by using good judgment and dressing appropriately. Follow these cold-weather tips to help prevent situations that can lead to hypothermia:

• Protect your body from cold and wet conditions by dressing in layers. Begin with long underwear made from a material (such as silk or polypropylene) that will wick moisture (including sweat) away from the skin. Cotton takes a long time to dry,  it does not insulate when wet and therefore is not a good fabric for this first layer. Add warm layers of outer clothing. Wool is an especially good insulator. Top it all off with a windproof and waterproof outer shell.

• Wear a hat. By keeping your head covered, you can prevent a significant amount of heat loss from your body.

• Be prepared! In winter, always carry an emergency kit in your car. Winter emergency kits should include  blankets, high-calorie food (such as several candy bars), a few candles, matches and a coffee can (in which to safely place a burning candle). For outdoor sports or other activities, bring along foul-weather gear and any other gear you may need (for instance, if in the wilderness, fire-starting materials and a makeshift shelter).

• During cold-weather activities, keep moving, eat high-calorie foods and bring along an insulated container of tea or hot chocolate.