Hypothermia: Chilled to the Bone

Column by Dr. Tim Moser

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By Dr. Tim Moser, Denver House Calls in Denver
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Peter was feeling very cold. He took the opportunity to warm up and get outdoors with a hike alone in the remote backcountry of the Colorado mountains on a sunny spring day.

By noon, however, the unseasonably warm temperature tempted Peter to take off his light jacket and tie it around his waist. The lure of nature pulled him deeper and deeper into the woods.

While attempting to cross a small stream by walking across a fallen tree, Peter slipped on the wet bark and fell into the water. Although the stream was shallow, his clothes were soaked, and his cell phone was now dead. Worse still, as he turned to make his way back to his car, he noticed the grey clouds of an approaching storm on the horizon, closing in fast.

Soon the wind was howling, and Peter was forced to find shelter while still a mile or so away from his car. While walking, he was able to keep somewhat warm. But as he lay huddled behind an outcropping of rocks, Peter started shivering uncontrollably and became increasingly confused and disoriented in the storm.

By morning, the storm had passed, but Peter was so incapacitated by cold and weakness he was unable to make it to his car. Later, he recounted vague memories of being rescued by a search team and taken to a local hospital for treatment.

The Basics

Hypothermia literally means "low temperature." It is a medical condition defined as a body temperature of 95 degrees or less, and can be fatal without proper treatment. As you would expect, hypothermia is more common in the winter months, but it is possible during the warmer times of the year as well.

Warm blooded animals (including humans) require a very narrow temperature range to keep the organs and various systems of the body happy. If the temperature drops below a critical level, then problems develop very quickly.

How Does the Body React?

The nervous system is especially sensitive to a drop in body temperature.

In the early stages of hypothermia, the prominent symptom is feeling cold. This is soon followed by shivering and the appearance of "goosebumps" on the skin-the body's attempt to generate and retain heat.

If the body is successful in generating heat, then all is well. However, if providing adequate heat is not possible, then the body temperature starts a low decline. The brain responds by becoming less efficient, resulting in clumsiness, followed by confusion, and eventually coma and death.

Some victims of hypothermia have performed outlandish things, such as peeling off protective clothing, or becoming combative. Most victims of a low body temperature simply become less active, and slip into unconsciousness.

The heart and lungs do not work well when cold, either. As body temperature drops, a point is reached where the conduction system of the heart is affected. Eventually a heartbeat cannot be generated. The heart slows, and eventually stops. This is followed quickly by a lack of breathing, and apparent death.

The lowering of body temperature also decreases the body's need for oxygen, however. If treated in time adequate warming and CPR can make it possible for a hypothermia victim to be successfully "brought back to life."

The old adage in emergency medicine is "you're not dead until you are warm and dead". It is uncommon to see such miraculous recovery of near-fatal hypothermia with treatment, but such recoveries have occurred in the past.

Taking Precautions

Hypothermia is best prevented by wearing adequate clothing when going out into the cold. When traveling to remote regions (even by car), use common sense and have extra clothing, drinking water and blankets with you at all times.

If clothing becomes wet, it is essential to remove the wet clothes as soon as possible, since the cold water in the clothing can overwhelm the body's ability to compensate by making more heat.

Those at highest risk for hypothermia include the very young, and the very old. This is due to a combination of a reduced ability to generate extra heat when needed, and in some cases a lack of mobility to move to a warmer area (infants are unable to turn up the thermostat). Wearing warm clothes (and bundling infants when going outdoors) is essential.

Want more information about hypothermia?

http://www.bt.cdc.gov/disasters/winter/faq.asp

http://www.mayoclinic.com/health/hypothermia/DS00333