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Bitter cold: the basics of hypothermia

Corey Templeton

In these cold winter months, the risk for hypothermia rises. You don't have to be an outdoor enthusiast or an avid hiker, in fact, don't even have to be outside to develop hypothermia. A few degrees means the difference between a normal core body temperature, and a temperature dangerously close to hypothermia.

This week on "Take Care," we speak with Dr. Chris McStay, chief of clinical operations in the Department of Emergency Medicine at the University of Colorado School of Medicine, about hypothermia and how to avoid it.

Lorraine Rapp: What exactly is hypothermia and what are the physical effects on the body?

Dr. Chris McStay: Hypothermia is, by definition, a core body temperature of less than 95 degrees Fahrenheit. There’s three different broad categories of hypothermia – mild, moderate and sever. Each of those categories can have their own individual manifestations, which can range from, in mild hypothermia just mild confusion, some slurred speech; in moderate hypothermia, lethargy, severe confusion; and then in severe hypothermia, complete loss of consciousness, and really those patients can appear dead.

Linda Lowen: If we’re talking about mild hypothermia, is that something that someone may go through temporarily and they don’t necessarily need to have medical treatment, they just need to be warmed up? Or is it any level of hypothermia needs medical attention?

Dr. McStay: Mild hypothermia is probably between 90 to 95 degrees Fahrenheit. Most of those patients will be awake and alert, maybe a little confused and obviously cold and typically shivering. And remember one of the big risk factors is being in the cold, but also being cold and wet. And shivering is really the main mechanism by which the body generates extra heat to rewarm ourselves. By getting them out of those environments, getting them into a warm environment, covering them with blankets and allowing that individual to shiver, maybe giving them some warm fluids, they’ll usually do just fine. Once you start to get colder, somewhere probably below 82 or 83 degrees Fahrenheit, the body starts to lose its ability to shiver. And so at some point in this continuum of temperature, as you get lower and lower, the body can’t quickly rewarm itself. So at that point, there are other interventions that need to occur in a hospital setting.

Rapp: Let’s talk briefly about some first aid do’s and don’ts. Because I was alarmed when I read that it’s dangerous to apply a warm compress to the arms or legs of someone with hypothermia.

Dr. McStay: What you’re referring to is one of the concepts which is called an afterdrop. You have someone who is very, very cold, the body typically shunts blood away from the hands and feet and arms and legs and tries to keep warm blood in the core of the body to maintain the central functions of the body, if you will. In some individuals, once you start to rewarm them that cold blood returns to the core of the body and can actually make it a bit more difficult to rewarm individuals, so it’s referred to as core afterdrop. The first thing to do from a basic first aid perspective for individuals that are exposed in environments that are cold is obviously to get them out of that environment as quickly as you can and get them into a warm environment. Often these individuals will have wet clothing on them – so their socks, their shoes. And remember cotton that is wet is really bad. It loses its insulating capacity. We always say, “cotton kills;” it’s one of the maxims of hypothermia and outdoor wear. If it’s dry, it’s probably okay to leave them in it. One of the chief tenets of rewarming individuals is really to focus on rewarming the core of the body and that the arms and legs will eventually be warmed up. And that’s not to say that if someone’s hypothermic you should avoid covering their arms and legs. I think one of the best ways to rewarm somebody who may be removed from a cold environment, especially in an austere, maybe a camping environment, is to put them into a sleeping bag. I wouldn’t say that you should avoid rewarming arms and legs in that situation, because it’s very difficult to do so, but that is one of the concepts of the afterdrop.

More of this interview can be heard on "Take Care," WRVO's health and wellness show Sunday at 6:30 p.m. Support for this story comes from the Health Foundation for Western and Central New York.