MTN MEDICINE: How to Recognize and Treat the First Signs of Hypothermia in the Backcountry

November 25, 2019
signs of hypothermia
Illustration by Jon LavalleyAMC’s medical advisor, Dr. Tom Trimarco, discusses what to do if you encounter someone showing signs of hypothermia in the backcountry.

Dr. Tom: If I encounter someone in the backcountry showing signs of hypothermia, what should I do?

Anyone who enjoys the Northeastern outdoors should possess basic knowledge in recognizing and treating hypothermia. While we sometimes think about hypothermia as a winter problem, it can set in any time of the year. There have been documented deaths in every season due to hypothermia on Mount Washington alone.

Hypothermia is defined as a core body temperature lower than 95 degrees Fahrenheit. When the body’s heat loss is greater than its heat production, hypothermia is possible. Early signs include shivering, slurred speech, clumsiness, and impaired judgment. As patients cool even further, they will actually stop shivering; their heart rate and breathing will slow; and they will become increasingly lethargic until they lose consciousness. Continued cooling will lead to cardiac arrest and, ultimately, death. 

If you’re outdoors with someone exhibiting any of these signs, first treat and stabilize any other injuries to the best of your ability. Next, work to prevent further heat loss by insulating the patient from the environment. If you are able to provide shelter from the elements, remove wet clothing and layer the patient with thick insulating clothing, including a hat. Wrap the patient in a dry sleeping bag or blankets, followed by a windproof and waterproof vapor barrier, such as a reflective blanket or tarp. Lastly, don’t forget to insulate the patient from the cold ground by placing them on a sleeping pad or backpack.   

After limiting heat loss, your next goal is to provide the patient with easily digestible calories that will fuel the body to help maintain shivering, which creates body heat. If your patient is alert enough to swallow, warm, sweet drinks—like hot chocolate—are good options. Foods containing simple carbohydrates, like energy gels or maple syrup, work well, too. 

If you have warm water bottles or chemical heat packs, place them near the patient’s armpits and torso (not directly on the skin) for an external source of warmth. This external rewarming is critical in patients with moderate or severe hypothermia who are showing altered consciousness, as they can no longer generate their own heat. Handle advanced hypothermia patients gently, as their hearts are quite irritable, and jarring movements can cause fatal heart rhythms.

If the patient can walk when you first encounter them, they may be able to be insulated, fed, and walked to safety. If not, keep the patient horizontal and contact local emergency response resources to aid in evacuation while sheltering the patient to the best of your ability.

Thomas Trimarco, MD, is AMC’s medical advisor. He is an emergency physician, an EMS medical director, and a faculty member of the Wilderness and Austere Medicine Fellowship at Dartmouth-Hitchcock Medical Center in Lebanon, N.H. Got a question for Dr. Tom? Send it to amcpublications@outdoors.org for a chance to be featured in a future issue.


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Dr. Tom Trimarco

Dr. Tom Trimarco is AMC's medical advisor. In his quarterly MTN MEDICINE column, Dr. Tom answers common questions about safety and first aid in the backcountry. Submit a question for Dr. Tom to amcpublications@outdoors.org for a chance to be featured in a future issue.