Hypothermia

Normally, the body balances heat gain with heat loss and the temperature stays relatively the same. When exposed to low temperatures for a long period of time, the body develops hypothermia. The definition of hypothermia is a body temperature of less than 95 degrees Fahrenheit.

It is the hypothalamus that controls body temperature. It responds to lower temperature by increasing metabolic rate. Most of the heat is lost via the skin through processes such as conduction, convection, evaporation and radiation. The colder the body gets, the more likely the person is to shiver, which increases the metabolic rate and contributes to the formation of heat. If this doesn't work, the core temperature of the body will decrease.

The fall of temperature means that blood is shunted away from the extremities in order to keep the heart, kidneys, brain and lungs warmer. The brain and the heart are most sensitive to cold temperature because they involve electrical activity, which slows and malfunctions because of cold temperatures. The lower the temperature, the higher is the risk of death.

The cause of hypothermia is usually exposure to cold weather while wearing inadequate clothing. Immersion in water makes the problem much worse and it can take just a few minutes in freezing water to die from hypothermia. Risk factors for hypothermia include being very young or being very old. Elderly people have the highest risk. Abnormal mental status makes it difficult to know that you're out in the cold too long. Certain medical conditions put you at higher risk, including having peripheral neuropathy, diabetes, thyroid disease, adrenal disease or pituitary disease, having a spinal cord injury or suffering from strokes or brain tumors. Having sepsis can cause a lowered body temperature rather than a fever. Substance abuse can put you at higher risk for hypothermia. And certain medications, such as psychiatric medications put you at higher risk for this condition.

Signs and symptoms of hypothermia include shivering, which is an early sign of hypothermia. Hunger and nausea are also early symptoms; they give way to a feeling of apathy. Worsened hypothermia yields lethargy, confusion, slurred speech and loss of consciousness. Coma then gives way to death. Some people get so confused that they begin to take their clothes off because they believe they are too hot. Brain function ceases when the body reaches a temperature of 68 degrees Fahrenheit. Ventricular fibrillation occurs at temperatures below 82 degrees. This causes cardiac arrest.

The diagnosis of hypothermia depends on the circumstances. The individual is usually in a cold environment, has a low core body temperature and exhibits symptoms consistent with hypothermia. In the elderly primarily, hypothermia can occur indoors at relatively normal ambient temperatures. You need to get a rectal temperature because an ear or oral thermometer will be inadequate. Besides the actual diagnosis, you need to look at the underlying factors that contribute to hypothermia as outlined above. There can be a low blood sugar in diabetics with hypothermia and there can be head trauma in alcoholics who fall outside.

Treatment of hypothermia includes first aid to any problems and removing them from the cold environment. Wet clothing needs to be taken off and replaced with dry clothing or dry blankets, including a covering for the head. If you are not in a hospital, you should call 911 for ambulance transfer to a hospital. Monitor breathing and pulse and if absent, initiate CPR. Don't handle the person roughly as you can trigger ventricular fibrillation in an irritable heart. Begin rewarming by having warm compresses pressed against the chest, neck and groin area. Do not use hot water. Use warm blankets or body to body contact if you are outside. If the patient is really suffering from hypothermia, you need to use active rewarming. This means using warmed IV fluids, warming blankets and the use of warm, humidified air. There are blankets filled with warmed air that can begin to raise the temperature of the person's body. Serious hypothermia may respond to heart bypass or dialysis in order to more rapidly warm the body.