Experts give tips on recognizing, avoiding hypothermia
Clothing, knowing survival skills may help save a life
Conduction, convection, evaporation and radiation. These terms may seem like science-class abstractions, but for a snowmobiler whose machine breaks down on a bitterly cold evening, they are relentless natural laws that could result in a death sentence. Two physicists — John Sohl, professor at Weber State University, Ogden, and Dr. Wayne Askew, who is a professor, chair of the Division of Nutrition at the University of Utah College of Health, and a physician — offered tips about hypothermia. The condition is defined as an abnormal drop in a person’s temperature. Just a slip from the ordinary 98.6 to 96 degrees can be life-threatening, according to the National Institute on Aging. Older people and the very young are at special risk. The institute posted a discussion of the subject on the Internet at www.niapublications.org/agepages/hypother
• Conduction is heat exchange through contact, said Sohl. “If you have good insulation between your hands and the handlebars of a snowmobile, ski poles, anything you’re holding,” one can minimize heat loss through conduction. “The idea is to reduce the amount of heat flow when you touch something cold.” Good-quality pants are a must for outdoor activities during the cold months. That way, “if you sit down on an icy log while you’re hiking, or you sit down on a cold park bench,” he said, “you won’t lose heat through your butt.”
• Convection involves wind chill and air flow. “You want to have clothing that blocks the wind,” he said. Sweaters are great when sitting before a fireplace indoors. “But if you’re outside, sweaters are not that good because the wind blows right through them.” It’s important to wear some kind of “shell” to block the wind, maybe with a sweater beneath. A heavy coat or a tight nylon windbreaker may do the job.
• Evaporation happens whenever moisture goes from one’s skin into the air. If a person is outside splitting wood on a cold day, he may work up a sweat. Taking a break, peeling off clothing, can cause real trouble, should the cooling continue to dangerous levels. Instead, Sohl advises, wear layered clothing. “If you have clothing that’s layered, you can strip a few of the layers off while you’re working hard.” Then, when resting, put some of them back on.
• Radiation. Heat can radiate away from a person into the icy air. At night the effect is even more pronounced. “As soon as you have the inky blackness of space to radiate heat into, you’ll cool off pretty fast,” he said. Sohl advises taking a lightweight space blanket when going into the back country. The inexpensive covering blocks the wind, stops evaporation, and keeps heat from radiating away. Going outdoors, people often try to reduce the amount of material they have to carry with them. He warns that the last things they should do away with are gloves and a hat. Without a hat, a person can “lose a huge amount of heat” because of the high blood flow through the head. As far as gloves are concerned, he said, “If your hands are too cold to work, you can’t save yourself. But if your hands work, at least you’ll have a fighting chance.” Askew said if a person is exposed to the cold, exercise can help, at least for a time. Friction from all that movement will build up heat, and fend off the penetrating cold. But exercise can’t be sustained forever. At that point, when a person is too tired to continue exercising, shivering kicks in — and that’s a good thing. “It’s something you want to happen,” he said. “It’s an involuntary muscle contraction” and this shivering, too, heats the body. Askew said nutrition can help stave off the dangers of hypothermia. “It’s been pretty well established that you certainly want to avoid low blood sugar,” he said. People with hypoglycemia, low blood sugar, don’t shiver as long or as vigorously. “You need to keep your muscles well supplied with carbohydrates,” which supply the calories that are burned to heat the body during shivering. Getting ready for an outdoors experience can be something like preparing for a race, he said. “Carbohydrate loading, if you know you’re going to be exposed to cold, is probably a good idea,” he said. Going into the wilds isn’t the only way to get slammed with hypothermia. “Urban hypothermia,” which hits the homeless and the elderly, is a huge threat, according to Sohl. When a cold front sweeps through and people die, “in most cases it’s because they got cold in their home,” he said. The elderly often can’t sense temperatures as well as younger folks. They also get cold easier because their metabolism is lower. Oftentimes they are on fixed incomes. “They’ve got the temperature cut way back to save on energy costs,” he said. “They just get too cold. They go to sleep and they never wake up.” Sohl advised checking on homeless and elderly people. Even then, it could be a real task to discover if hypothermia is present. The National Institute on Aging points out that older people may not want to complain and may not talk about how cold they are, or may not even realize it. “Look for the ‘umbles,’ — stumbles, mumbles, fumbles and grumbles,” the institute advise. For older people , the thermostat should be set for at least 68 to 70 degrees. Watch out for confusion or sleepiness; slowed, slurred speech or shallow breathing; weak pulse or low blood pressure; a change in behavior or appearance; chilly rooms, or other signs the person has been in a cold place; poor control over body movement or slow reactions. Also, says the institute, be aware of “a lot of shivering or not shivering; stiffness in the arms or legs.”