Tuesday, February 15, 2011

The Deadly Season

Cherry Blossoms and Early Spring

Regardless of our experience level, there’s one topic we can’t think about or hear about enough. Yeah, I know, we think we’ve heard it all, and yet too many among us keep making the same mistakes. Hypothermia.

Gus Bianchi sent me an article about two teenagers dying on a Florida canoe trip---from hypothermia---in The Sunshine State. (Check link under Comments, Survival Fire Starter) The words that popped right off the screen at me were, “We were dressed for the weather.” The weather was warm, but the water was 58-60 degrees, a temperature at which the rescue divers wear wetsuits, and still remain in the water only about ten minutes.

Two weeks ago, George Feeter, age 39 and a kayaker with 15-yrs. experience, went paddling on Falls Lake, in North Carolina. It was one of those late winter warm spells when the air gets toasty and inviting. He was seen departing wearing shorts and a T-shirt. An exposure suit was found among the flotsam when his boat was recovered, so there was supposition that maybe he had gotten overheated and had lost balance while trying to wriggle out of the suit, but no, he had been seen launching while ’dressed for the weather’. As it got dark, people ashore could hear someone yelling for help. The boat and gear were found, but it was another couple days before George was. We need to remember that, for most regions, change in water temperature lags behind air temperature by about two months. The water is often colder in April than it was in December.

The safe water temperature where we don’t have to be concerned about hypothermia is 80-deg. F. This is the temperature at which the body can generate heat as quickly as it’s being lost. In St. Thomas, U.S. Virgin Islands, the water temperatures averages 79-deg. in winter and 83-deg. in summer. Yet, even there, you will see windsurfers and divers wearing wet suits. On the other hand, if it is an 80-degree April or May day even in temperate regions of the country, the water temperature is often still where it can kill in 15-30 minutes. If we are on Lake Superior, where the temperature almost never exceeds 70-deg., or a stream fed by spring thaw in the hills, it can still be frigid in mid-summer. We need to be mindful of protection from water temperature, not air temperature.

The body will tolerate about a 4-5 degree fluctuation in temperature. We all know how debilitating a fever of 103 is, but a core body drop in temperature as much in the other direction, to 95, is just as disabling, and 95-deg. is by definition, hypothermic. Even before shivering starts, the victim becomes confused, dizzy, and uncoordinated, conditions you don’t want to experience around a tippy boat or out of reach of assistance. Once shivering begins, the symptoms that accompany that are stumbling, poor decision making, and apathy, or a lack of concern for one’s condition. Heat loss in water is 23-25 times faster than in air, and if you decide to swim for shore, it had better be close. Swimming or any movement accelerates heat loss another 35-50%. Even when you get out of the water, heat loss in wet clothing is only 10% less than if you were still in the water, especially if you‘re wearing cotton. Wool and synthetics like fleece are better. What needs to be done to survive must be correct and immediate. If you have dry clothing with you (and you should), even if you have to do it standing naked in knee-deep snow, you want to get into them quickly. If core temperature gets to 82-deg., the heart will go into ventricular fibrullation. Then, you need to find a heat source. Start a fire, wrap a mylar survival blanket behind you, holding it out like angel wings to deflect and concentrate the heat to your torso. If you have chemical hand warmers, put them in the groin or armpits with a protective cloth layer between them and the skin. Concentrate on warming the torso, not the arms and legs. Take no alcohol. Do not rub cold areas of limbs, hands, or feet. As soon as you can move, seek medical treatment, or call for help. You’re not out of danger yet. True, it’s not a happy topic, but an important one.

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