Friday, April 12, 2013

Hypothermia--Slowly Freezing to Death

A normal internal (core) body temperature is 98.6 F (37 C). Hypothermia occurs when the body is subjected to a cold environment for a long enough period of time that the internal body temperature drops to less than 95 F (35 C). Hypothermia can also occur when the body’s temperature regulation system is deranged.

Inside the brain, the hypothalamus (a primitive part of the brain) is responsible for temperature control. Normal metabolic processes generate the body’s heat. When too much heat is lost through the skin (or in the case of fever) shivering produces heat through muscle action.

Continued heat loss results in shunting of blood away from the skin internally, to support the internal organs—especially heart and brain. As the body’s core temperature drops, metabolic processes slow, and the heart rate, respiratory rate, and brain waves all slow down. As the internal temperature continues to drop, death will ensue.

Environmental exposure accounts for the vast majority of hypothermia. Individuals with alcohol on board are more susceptible as alcohol dilates the skin vessels and accelerates heat loss; drinking brandy to “stay warm” while scooping snow is a bad idea! Low thyroid, advanced age, drug abuse, and some medications (vasodilator drugs) increase the likelihood of environmentally-induced hypothermia. Psychiatric conditions like dementia—that might cause an individual to wander away without a defined destination—are a risk factor.

Brain conditions that affect thermoregulation ability can put someone at risk.

The gradual onset of hypothermia makes it harder for someone to know what’s happening. Onset may lead to a phenomenon known as paradoxical undressing, where the person sheds clothing even though they’re freezing to death. Drowsiness, followed by drifting into sleep and death follows.

Treatment involves getting the person to a warm environment, out of wet clothes (if applicable) and rewarming. External warmth—hot water bottles, warming blanket, even body-to-body contact—is applied. In a medical setting, warm IV fluids, warmed air, and heated blankets can be used. Warm fluid can be infused into the abdominal cavity.

In worst-case scenarios, the patient can be rewarmed using heart-lung bypass, warming the blood as it goes through the machine.

Caution for heart rhythm disturbances involves avoiding moving the patient more than necessary. As people with profound hypothermia have been successfully resuscitated, most doctors consider a hypothermic patient to be potentially salvageable until they are warm.

The biggest consideration is to avoid situations that may lead to hypothermia, primarily avoiding prolonged exposure to cold weather.
Questions? Comments?

Kelly has worked in the medical field for over twenty years, mainly at large medical centers. With experience in a variety of settings, chances are Kelly may have seen it.
Sometimes truth seems stranger than fiction in medicine, but accurate medicine in fiction is fabulous.
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  1. A very interesting, and topical, post for me since the characters of my WIP are currently stuck in a blizzard in the Highlands of Scotland! Thank you!

    1. Very welcome! Glad it's timely for you.
      Cheers, Kelly

  2. Now I know where to go if I'm looking to write medical scenes. Thanks, Kelly.

  3. This is great! I'm writing a book right now that uses this exact info; my character has frostbite and a former army medic takes care of her...and so forth. I did lots of research...thanks for posting this.

    1. Good luck with your book, Lisa.
      Cheers, Kelly

  4. Thanks, Kelly. Useful info.