What is hypothermia? 

The body maintains a relatively stable temperature whereby heat production is balanced by heat loss. Normally, the core body temperature (when measured rectally) is 98.6 degrees F or 37 degrees C. When the outside environment gets too cold or the body's heat production decreases, hypothermia occurs (hypo=less + thermia=temperature). Hypothermia is defined as having a core body temperature less than 95 degrees F or 35 degrees C. 

What causes hypothermia? 

Hypothermia most often occurs because of prolonged exposure to cold weather. Inadequate clothing for conditions may not provide enough insulation for the body to prevent heat loss. Immersion in water hastens hypothermia, and just a few minutes in cold water may be fatal. 

What are the signs and symptoms of hypothermia? 

The body starts to slow as the temperature drops. Aside from the cold that is felt and the shivering that may occur, mental function is most affected initially. A particular danger of hypothermia is that it develops gradually, and since it affects thinking and reasoning, it may go unnoticed.

The body maintains a relatively stable temperature whereby heat production is balanced by heat loss. Normally, the core body temperature (when measured rectally) is 98.6 degrees F or 37 degrees C. When the outside environment gets too cold or the body's heat production decreases, hypothermia occurs (hypo=less + thermia=temperature). Hypothermia is defined as having a core body temperature less than 95 degrees F or 35 degrees C. Hypothermia most often occurs because of prolonged exposure to cold weather. Inadequate clothing for conditions may not provide enough insulation for the body to prevent heat loss. Immersion in water hastens hypothermia, and just a few minutes in cold water may be fatal. The body starts to slow as the temperature drops. Aside from the cold that is felt and the shivering that may occur, mental function is most affected initially. A particular danger of hypothermia is that it develops gradually, and since it affects thinking and reasoning, it may go unnoticed.

• Initial hunger and nausea will give way to apathy as the core body temperature drops.
• This is followed by confusion, lethargy, slurred speech, loss of consciousness, and coma.
• Often the affected person will lie down, fall asleep, and die. In some cases, the patient will paradoxically remove their clothes just before this occurs.

The decrease in brain function occurs in direct relationship to the decrease in body temperature (the colder the body, the less the brain function). Brain function stops at a core temperature of 68 F (20 C). 

The heart is subject to abnormal electrical rhythms as hypothermia progresses. Ventricular fibrillation, a disorganized rhythm in which the heart is unable to pump, may occur at core temperatures below 82.4 F (28 C). This is one type of cardiac arrest. 

Can hypothermia be prevented? 

While medical emergencies can occur in association with hypothermia (for example, people with diabetes who develop very low blood sugar), most cases of hypothermia are preventable with good planning and good judgment.

• Wear appropriate clothing for the weather.
• Prepare for the worst when enjoying an outdoor activity if cold weather is a possibility. If choosing to drink alcohol, make certain there is a sober person who will be responsible for your safety.
• For the elderly and the poor who may not have adequate home heating in the winter, communities should insure that safe housing is available. Shut-ins should have routine social service or family contacts.