Foley: Backcountry survival: hypothermia
October 25, 2016
When someone dies after getting lost or stranded in the mountains it's not usually from starvation or dehydration. The "Survival Rule of 3" postulates that you can survive for three minutes without air, three hours without shelter (in a harsh environment), three days without water and three weeks without food. Assuming you've got your head above water, the most immediate threat is from exposure to the environment.
Hypothermia is an environmental injury that occurs when the core body temperature is lowered due to the body losing heat faster than it can produce heat. By definition, hypothermia occurs when the body temperature falls below 95.0 °F. If left unchecked, hypothermia can be fatal.
Symptoms of hypothermia progress from mild to medium to severe as the core temperature gets lower. It is important to understand that hypothermia can occur even on a nice day, especially as a result of wet clothing or wind exposure.
Since symptoms occur gradually, a hypothermic person may not recognize that they are in trouble. Awareness of symptoms in your companions is critically important in a backcountry environment. Symptoms of mild hypothermia include:
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Lack of coordination
Increased heart rate
Recognition of the symptoms and treatment of the subject during this mild phase is vitally important. If left unchecked, and with further lowering of the core temperature, moderate and severe hypothermia can occur and may be difficult to reverse without definitive medical care. Hypothermia symptoms evolve and worsen:
Shivering, although as hypothermia worsens, shivering stops
Clumsiness or lack of coordination
Slurred speech or mumbling
Confusion and poor decision-making, such as trying to remove warm clothes
Drowsiness or very low energy
Lack of concern about one's condition
Progressive loss of consciousness
Slow, shallow breathing
Earlier this fall we rescued a woman who had injured her hip near Bottle Peak. We were planning to carry her out with a litter but by the time we got to her around sunset she was exhibiting symptoms of moderate hypothermia – she had stopped shivering, was confused and had a weak pulse. We decided that she needed a helicopter ride instead.
Besides respiration, the body loses heat by four mechanisms: evaporation, radiation, convection and conduction. Blocking heat loss from each of these mechanisms is important to prevention and treatment of hypothermia.
Treatment of severe hypothermia in the field can be futile, so early diagnosis can save a life. For mild hypothermia simply adding clothing and forcing exercise to produce heat is an option. Eating quick energy food and warm, sweet liquid (not alcohol) is helpful.
If more advanced hypothermia requires an emergency response the first action would be to prevent further heat loss by getting the patient out of the wind and into a tent or other shelter. Start a fire or a stove for heat and provide artificial heat like heat packs or a hot water bottle. Add insulation around the patient and remove and replace any wet clothing. All of our members carry extra clothing and chemical heat packs for warming a patient. If the patient is alert and awake warm liquids and energy foods can be provided. Especially important is preventing conductive heat loss by insulating the patient from the ground with a pad, pack or blanket.
Warming takes time. Be patient and persistent.
Be aware that cardiac arrest is a danger in advanced hypothermia. Keep the patient lying down and be gentle if movement or evacuation is required.
Of course accidents can happen. Falling into a lake or stream, getting caught in an avalanche or a fall or injury that prevents travel could set you up for hypothermia. In these adverse situations prevention by being prepared should always be the first line of defense. Having extra clothing (not cotton that stays wet and cold), an emergency shelter and fire starting capability can all help reverse or prevent hypothermic symptoms. In the winter or above treeline a stove is invaluable for heat and hot liquids.
Hypothermia can be a life threatening situation. Be prepared by carrying the right gear, be aware of symptoms in your partners and start treatment early before irreversible core cooling occurs. Call for help sooner rather than later. Severe hypothermia requires emergent transport to a hospital or clinic.
Greg Foley is a member of Grand County Search and Rescue and has been a mountain rescue volunteer for 36 years. He can be reached by email at firstname.lastname@example.org. The GCSAR website can be found at grandcountySAR.com or on Facebook/GCSAR.
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