Cold can be a serious, even life threatening problem for us as we venture outdoors. Hypothermia is a problem that we must be aware of. It is important to remember that while winter is when we think most about hypothermia, it can occur any time of year. All we need for hypothermia to be a problem is cold, wet and windy conditions.
Because frostbite is freezing of tissue, it is uncommon to see frostbite when outside temperatures are above freezing (32 degrees). Hypothermia, on the other hand, is most commonly seen when outside temperatures are between 30 and 50 degrees. Temperatures below 50 degrees can be seen during most months of the year, making hypothemia a much more common problem associated with cold and the outdoors.
The biggest problem we have with hypothermia is that it tends to "sneak up on us." One of the first organs to be affected by cold temperatures is the brain. This often leads to our not recognizing the problem during the early stages. It is very important that we recognize the potential for hypothermia and prevent it from occurring. Any time you are experiencing temperatures below 50 degrees and/or there is a breeze or you get wet you must be aware of hypothermia.
The key to prevention and treatment of cold emergencies is the five methods of heat transfer. These methods of heat transfer can increase heat loss if not controlled, or can be used to increase heat gain when treating hypothermia. The five methods of heat transfer are conduction, convection, evaporation, radiation and respiration.
Heat can be lost by each of these methods, leading to hypothermia. Conduction occurs when you come into contact with a cold object, such as sitting on a cold rock, touching cold metal or falling into cold water. Convection causes heat loss when cold air or water circulates across the body, such as a cold wind (wind chill factor) or a stream. Heat loss by evaporation occurs when moisure on the surface of the body becomes airborne. This does not require a hot day to occur and the moisture can come from sweat, rain, snow or falling into a lake or river. Radiation occurs when heat escapes from your body into the air in much the same way as heat radiates out from a fire. A great deal of heat can be radiated out from your uncovered head. Heat is also lost through during normal breathing (respiration). If the air we breathe is colder than body temperature, our body heats the air to body temperature before it reaches the lungs. When we breathe out, much of that heat is lost into the air.
These methods of heat transfer can easily come into play on an outing where the last thing you would worry about is cold problems. Let's look at a possible occasion. It is late on a Saturday afternoon in mid-June at Strawberry Reservoir. You are out on your fishing boat. The temperature at midday was about 70 degrees, but the sun has started to go down and the temperature now is about 60 degrees. One of those rapid-forming storms begins to develop. The wind begins to pick up (convection) and the temperature begins to drop as the skies become dark. You decide to take refuge in a nearby cove and "ride it out."
The storm hits and it rains hard, but for only about 15 minutes. Your hair and clothing are wet, causing you to lose the insulating factor and allowing your to lose heat by radiation. The cold wet clothes touching your skin conduct heat away from you and the moisture allows evaporation to occur.
The air that you are breathing is in the low 40s at this point. As is always the case, the fish start biting as soon as you consider going in. You decide that there is at least another hour of light and you want to stay out on the lake. Within 15 minutes you have lost enough heat that your brain is no longer functioning properly and you do not notice that you are shivering severely. As you continue to lose body heat, your muscles become stiff. It is difficult to cast so you just let your bait sit where it is at. Due to the muscle stiffness, you are not moving around to generate body heat. Within 45 minutes, the outside temperature has dropped several degrees and your brain is chilled to the point where you have gone into a semiconscious stupor. How does this end? That depends upon the help that you receive.
The signs and symptoms of hypothermia can vary with each person and by how far the hypothermia has progressed. In general, the signs and symptoms can be grouped into four categories. The first is weather. Remember that COLD (below 50 degrees), WET (rain, snow, sweat, or falling into water) and WINDY (wind chill factor) equates to hypothermia.
The second category is shivering. Shivering is a natural response to cold, but if the shivering is severe or if the shivering stops without the person being rewarmed, they are experiencing some amount of hypothermia. The third category of signs and symptoms is muscle rigidity or stiffness. As the body loses heat, blood is kept in the core of the body to maintain the vital organs. This causes the arms and legs to become stiff and the person has difficulty performing simple tasks such as walking or buttoning a coat.
The fourth category of signs and symptoms occur as the brain is cooled. As the temperature of the brain goes down the person stops thinking normally. They become unaware of what is around them and may even think they are too warm and begin removing clothes. The victim's eyes often become glassy and they just stare into space. The victim may even begin to slur his/her speech or have difficulty speaking in sentences. As the brain continues to cool, they will slip into a semi-conscious or unconscious state.
As soon as these signs and symptoms begin to occur, treatment must begin. Treatment consists simply of warming the person up. This is very difficult to do if the person is continuing to lose heat. Immediately seek whatever shelter is available. If possible, remove the victim's wet clothes and place the victim in warm dry clothing or other protection. The victim cannot effectively warm himself/herself, so careful warming should occur. This could be body contact with a nonhypothermic member of your party, warming objects or clothing and placing them against the victim, submersing the victim in warm water or placing the victim in a warm environment such as near a fire or in a heated vehicle or building.
Be sure that the air they are breathing has been prewarmed by having them in a warm environment or at least have them breathe through a scarf. Efforts to rewarm the victim should be concentrated on the trunk or body of the victim. Active warming of the arms and legs should be avoided until the trunk is adequately warmed. Warming the arms and legs before the trunk has been adequately warmed can lead to a rush of cold blood in from the arms and legs that may critically cool the vital organs.
Do not give the victim warm fluids if he/she is having difficulty swallowing or if the level of consciousness is decreased. It is always a good idea to have the hypothermia victim evaluated by a physician as soon as possible after rewarming. If an emergency room or emergency personnel (ambulance) is readily available, then medical professionals should be the ones to rewarm the victim.
They key to hypothermia is prevention. Be aware of the potential for hypothermia in most of your outdoor activities. Dress for, or have clothing available to protect you from cold, wet and windy weather. There are many kinds of excellent clothing that will keep a fisherman warm and dry in the worst weather.
Seek shelter early, do not wait until someone has hypothermia. If active in a cold environment, take frequent rest breaks. These breaks should include something to eat in order to replace the energy you are using to be active and to warm yourself.
Avoid getting wet either from sweat or outside sources. Protect your head from heat loss. Some estimates say that up to 80 percent of the heat your body generates can be lost through the head.
Remember that this and most other problems can best be cared for after proper preparation and training. First aid classes are available to the community at reasonable cost from local chapters of the American Red Cross, the University of Utah Department of Health Education, most hospitals, many local fire departments and most continuing education programs at local high schools or colleges.