Medicine: The Hiker's Hazard

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Ignoring her hunger, Joan continued to climb. She was anxious to reach the summit of New Hampshire's 5,363-ft. Mount Madison and unwilling to delay her hiking companions. By midafternoon, she felt tired and dizzy; a few minutes later, after a shower had soaked her and her companions, she sat down, complaining of weakness and nausea. Concerned, some of her fellow hikers wrapped her in a poncho while others went for help. By the time rescuers arrived, Joan was shivering and unable to answer questions, her body temperature down to 95.8° and falling. Rushing her to a shelter near by, the rescuers fed her candy and orange slices for fuel, dried her off and wrapped her in hot blankets; soon her body temperature returned to normal.

Many of the hikers taking to mountain trails throughout the U.S. this summer will not be so fortunate. Hundreds of them will develop hypothermia, a rapid and uncontrolled lowering of the body temperature that some experts consider the greatest hazard facing hikers. In the past century, for example, it has killed several dozen people in New Hampshire's White Mountains alone. During one Memorial Day weekend, when a surprise storm caught five Sierra Club members on the flank of California's 13,165-ft. Mount Ritter, four of them died of hypothermia.

Simple Ailment. Physiologically, hypothermia is a simple ailment. When a hiker becomes chilled, his autonomic nervous system acts to restore heat by tensing the muscles and causing shivering. But if he is also hungry, tired and wet, the reactions become more radical. In an attempt to conserve heat, the blood vessels contract, reducing the flow of blood to the skin and other extremities. If the cold continues, other systems are affected. For reasons not fully understood, the central-nervous-system controls go awry and the body loses even more heat instead of producing or conserving it. Temperature plummets.

As body core temperatures continue to fall below normal, the mind becomes confused, cardiac and respiratory rates slow, and the hiker lapses into unconsciousness. When the body temperature drops to around 78°, death can occur quickly. A hiker who left his hypothermic companion propped against a tree on an Adirondack mountain trail last year found him dead when he returned with help less than an hour later.

Hardest Lesson. To treat hypothermia, doctors and mountain rescue experts counsel common sense. The first step should be to learn hypothermia's symptoms and act as soon as they appear, getting victims out of the wind and their wet clothes and then warming them. Conscious victims of hypothermia can be fed high-energy foods and warm liquids and placed in a sleeping bag (if possible with someone else to share body heat). Unconscious victims can be thawed by placing them in warm—but not hot—baths.