We are used to thinking of hypothermia as something Himalayan Mountain Climbers need to worry about, not something that threatens Indiana or Ohio college students who are simply trying to get to class!
But forewarned is forearmed. So while you are trying to remember where you put your woollies, a little reliable information on hypothermia is in order.
Your body is a biologic machine. And like any machine, it has a proper operating temperature range that must not be exceeded or you will “void the warranty” and incur serious injury or death.
The operating temperature is your core body temperature, the temperature that allows the heart and brain to work most efficiently. The body shunts blood and uses other strategies to keep the core body temperature constant.
Normal core body temperature is around 98 to just under 100 degrees Fahrenheit (or 36.5-37.5 centigrade – does anyone really think in centigrade?). Down to about 95 degrees you are reasonably safe, although your body is working hard to warm you.
If you are making repetitive scuba dives off the California coast, in 50-something-degree water, even wearing a wet suit you will be burning so many calories maintaining temperature that it is almost impossible to gain weight.
Mild hypothermia is core body temperatures from 90-95 degrees. You are shivering, which is rapid muscle contraction, a good strategy since muscles are the main heat generators in the body.
Your heart is pumping harder, as are your lungs, to supply those hard-working muscles with blood and oxygen. When you get like that, you usually have to pee – “cold diuresis” is the proper medical term. Some confusion starts to appear as the brain gets below its proper operating temperature. Time to find some shelter.
Moderate hypothermia is when core body temperature drops to 82 to 90 degrees. Now things are really not working well. The shivering is violent and almost uncontrollable. You are shivering so hard that coordinated activity like putting a key in a lock or starting a car is almost impossible.
Even walking is difficult and often results in stumbling. Your brain is as sluggish as your muscles, and confusion often prevents people from taking steps to save themselves.
Severe hypothermia is downright terrifying. Your core body temperature is now between 68 and 82 degrees. Your heart barely pumps at that temperature and everything misses the blood flow.
Your brain behaves like the most drunk you have ever been in your life – the falling-down-type drunk. You are essentially a zombie; perhaps even less animated.
Meaningful activity, like finding shelter is impossible. In your confusion, you may remove all your clothes, which occurs with surprising frequency, and of course rapidly leads to death. At this point you need to be rescued, with no help from yourself, or you will die.
Prevention is not that complicated. Many layers of insulating clothing on all areas of exposed skin will slow heat loss. Keeping active with outdoor activities also generates heat (cross country or downhill skiing, sledding or walking). People who get in trouble often get wet, which dramatically decreases the insulation value of what you are wearing.
Another frequent and not surprising finding is at least half of hypothermia cases involve alcohol. This is sort of a double whammy because alcohol impairs your ability to make sensible decisions about the cold. Alcohol also is a vasodilator, making your skin work like a radiator, the exact opposite of what you need.
The current Antarctic temperatures and wind affecting much of the Midwest and Eastern part of the country must be respected. Staying indoors in a heated, dry home is the safest place. If you have car trouble, stay in your car. Avoid any situation where coming in out of the cold is difficult to do. And finally – dress like the Michelin Man.
Stay warm, and be safe.
Donald Bucklin, MD (Dr. B) is a Regional Medical Director for U.S. HealthWorks and has been practicing clinical occupational medicine for more than 25 years. Dr. B. works in our Scottsdale, Arizona clinic.
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