Hypothermia and What you Need to Know to Stay Alive

I live in the foothills of the Sierra Nevada Mountains and every year people get lost and die in the winter.  Normally they are not properly equipped and die from hypothermia.  They drive to the snow in their nice warm car and go out to play on a sunny day, when it seems to be deceptively warm.  They end up straying of the trails and night sneaks up on them.  Without warm clothing, a way to start a fire, food or water, and no survival training, they succumb to hypothermia.

The human body temperature is usually maintained at a constant level of 97.7–99.5 °F.  If a person is exposed to cold, and their internal mechanisms cannot replenish the heat that is being lost, the body’s core temperature falls and you are suffering from hypothermia.

Here is a chart that shows how lose of core temperature affect yso

Here is a chart that shows how loss of core temperature affect you

Hypothermia can range from mild to severe.  Mild hypothermia can be treated with warm drinks, warm clothing and getting warm.  Moderate hypothermia is harder to treat.  Recommended treatments include heating blankets and warmed intravenous fluids.  In severe hypothermia, medical intervention is normally required to save the person’s life.

Hypothermia causes approximately 1500 deaths a year in the United States.   Body heat is primarily generated in your muscle tissue, while it is lost through the skin (90%) and lungs (10%).  Heat production may be increased 2 to 4 fold through muscle contractions.

A few years ago, a friend and some companions were caught in a severe blizzard in the High Sierra’s.  They were forced to spend the night in a lean-to on a ledge.  Now they were well dressed and had good equipment, but they were still in danger of hypothermia.

Because they could not get up and move around, they used isometric exercises to help raise their body temperature.  An isometric exercise is a form of exercise involving the static contraction of a muscle without any visible movement in the angle of the joint.  When you create the tension in your muscles, it creates body heat.  Tighten your muscles and hold them tight for a short period of time, maybe 30 seconds. The bigger the muscles the more heat.  Be careful not to generate any type of a sweat.  My friend, who taught for the US Marine Corp Cold Weather School at Pickle Meadows, said that this helped them stay warmer throughout the night.

Appropriate clothing helps to prevent hypothermia. Synthetic and wool fabrics are superior to cotton as they provide better insulation when wet and dry. Some synthetic fabrics, such as polypropylene and polyester, are used in clothing that is designed to wick perspiration away from the body.  Examples would be moisture-wicking undergarments.  Clothing should be loose fitting, as tight clothing reduces the circulation of warm blood. See my previous post Hypothermia, How to Dress to Avoid It.

I want to make one correction to my previous post.  In it I mentioned that you could lose up to 50% of your body heat from your head and neck.  I have since found out that this is incorrect.  Covering the head is effective, but no more effective than covering any other part of the body.

Remember that wet rainy weather with temperatures above freezing in the 40 and 50s can be just a dangerous as colder temperatures.

Stay well dressed and warm and carry survival gear.

Howard

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3 Responses to Hypothermia and What you Need to Know to Stay Alive

  1. Ed Harris says:

    When in the U.S. Navy we were taught if if we fell into cold water, to be aware of the 1-10-1 Rule.

    Take 1 minute to stop the panic – you’ve 10 minutes of physical ability to save yourself – and 1 hour of consciousness left.

    Here’s why.
    – See more at: http://live.cgaux.org/?p=872#sthash.lbSVVUcM.dpuf

    Additional information from the U.S. Coast Guard:

    “Research in Canada sheds additional light on human casualties associated with cold-water immersion (below 15oC or 59oF) and hypothermia that is often misunderstood or overlooked by specialists in the field. People often do not die of actual hypothermia but from a variety of problems where mild hypothermia causes them to lose their physical and mental ability to survive. A typical case is a victim in the water not able to keep their back to waves, inhaling the next wave, and dying from drowning in spite of a life jacket. It is the early period of the accident that victims do not survive water immersions even though they fall in the “safe” boundaries established on hypothermia survival charts.
    The majority of deaths (over half) occur in the two stages before hypothermia actually develops. This period is often ignored but where preventative efforts should be focused — protection against the short term incapacitating effects and protection from drowning. The study provides a variety of people such as emergency responders, coroners, lifesaving equipment manufactures, people in the maritime industry, etc., a better perspective of the problems and better identifies solutions for them.

    Four stages of cold-water immersion leading to incapacitation and death:
    • Stage 1, Initial immersion responses or cold shock;
    • Stage 2, Short-term immersion or swimming failure;
    • Stage 3, Long-term immersion or hypothermia;
    • Stage 4, Post-rescue collapse.

    At stage 1, a cold shock response can occur at water temperatures below 77o F. The shock severity is proportional to temperature (colder temperature, higher shock) and peaks between 50 to
    59o F. This partly explains many deaths that occur in water as high as 50o F, long before standard survival curves would predict. It is now thought that this is one of the greater threats.”

    https://www.uscg.mil/hq/cgcvc/cvc3/notice/flyers/Cold_Water_Survival_Hypothermia.pdf

  2. colomtns says:

    You posted the following statement; “that you could lose up to 50% of your body heat from your head and neck. I have since found out that this is incorrect.”

    When I cross country ski or hike I use a hat to regulate my body temperature and it works really well.

    Maybe when you are inactive there is not much heat loss from your head but when your are active, there seems to be a lot of heat loss from a person head. Just look at the pictures they show of football players with their helmets off during a cold weather game. You can literally see the heat radiating off their heads.

    Could you please tell me where you found out about this, because it is contrary to my own experiences.

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