Winter Survival Basics Module 2: Hypothermia

What is Hypothermia?

Hypothermia is caused by a drop in core body temperature below 95 degrees Fahrenheit. Hypothermia impacts a number of essential systems in our bodies including our cardiovascular nervous, and respiratory systems. If left untreated hypothermia can lead to a total failure of one or all of these systems resulting in death. Even if hypothermia is treated in severe cases long-term damage to the body is possible from a reduction of blood flow. This is most common in arms, legs, hands, and feet.

How Hypothermia Occurs 

Hypothermia occurs when our bodies lose heat faster than it can produce heat. Most of the body’s heat loss will occur through the skin, 90% of heat loss occurs through your skin. The other 10% of the body’s heat loss occurs through the respiration (breathing) process. 

Hypothermia is commonly caused by extended exposure to cold temperatures or being submerged in cold water. While this most commonly occurs in the winter months, it is possible to become hypothermic in warmer conditions. In spring the air temperature is warm, but water can still be very cold, extended submersion in recently thawed water can easily trigger hypothermia. Wind exposure also increases the risk of hypothermia, as the wind will displace the thin layer of warm air that surrounds our skin.

Young children and the elderly are more susceptible to hypothermia than other groups and while hypothermia is most common in temperatures below 40 degrees Fahrenheit, it is possible that long-term exposure of 60 degrees or less can lead to hypothermia in these more sensitive groups.  

Signs and Symptoms of Hypothermia include:

-Shivering uncontrollably in the early stages

-Slow, shallow breathing

-Feeling of being drowsy or exhausted

-Slurred Speech

-Loss of coordination and motor function

-slow and/or weak pulse

-In severe cases loss of consciousness and very little signs of breathing or pulse

Preventing Hypothermia

Preventing hypothermia is far better than treating hypothermia and there are a number of steps we can take to prevent our bodies from going into a hypothermic state.

Avoiding Extreme Cold

Let’s face it, even if you love the great outdoors there are times we should avoid it. During periods of extreme cold and wind, it is in our best interest to avoid prolonged exposure. The misconception that people often have is that if there is no snow, they will be safe outdoors in the winter, this is unfortunately a life-threatening misconception. It is also important to remember that the wind has a large impact on how fast our body cools and loses heat.

Proper Clothing and Layering

If you can’t avoid the cold, ensuring we have the appropriate clothing and outerwear is very important. Creating layers that will help insulate our body is vital for any long-term cold exposure. 

  1. Base Layer: base layers typically go beneath your other clothing, while there are many material options sold I only recommend a wool base layer. Wool is a natural material that animals use to help regulate their body temperature. Unlike cotton wool retains the ability to keep you warm when wet, and unlike synthetic materials, wool is naturally fire-resistant. For my base layer, I use Minus 33 Merino wool from head to toe. Wool socks are especially important as they will keep your feet warm and reduce the absorption of sweat and help prevent damage to your foot tissue.
  2. Mid Layer: This layer consists of your regular clothes, pants, shirt, etc. Again avoiding standard cotton is a good idea, especially if you may get wet or plan on being very active and generating sweat. Depending on the temperature you may include a fleece or insulated vest in this layer as well.
  3. Outer Layer: This consists of your coat, hat, gloves, and shoe/boot. It is important that you get the appropriate outer layers, as most “fashion” hats, gloves, and coats will do very little to protect you from the elements. An insulated coat or parka is the way to go, and I highly recommend you have one that is waterproof in the case of snow or rain. Wool beanies and gloves can serve as a good outer layer for your head and hands or be placed under a thicker hat and glove. For your feet, a solid boot hiking boot that is waterproof is beneficial because the waterproofing often serves as insulation. For long-term extreme cold situations, insulated boots are a good choice.  

 Vehicle Considerations

While people often view their vehicles as a potential shelter from the extreme cold, if they are not running they do not produce heat and will quickly become very cold inside. While this may shelter you from the wind, it will, at best delay hypothermia. What vehicles do provide us is the ability to store some essential supplies. 

  1. Blankets: Keeping blankets in your vehicle, especially wool blankets, can provide us a much-needed form of insulation in a cold weather emergency.
  2. Spare Clothing: Travel with a spare set of appropriate winter clothing, if the clothing you are wearing become wet, it hurt us more than they help us and can lead to hypothermia. That spare set of warm and dry clothing can potentially save your life.
  3. Survival Kit: Having a survival kit, especially one that provides a means of making fire and the tools you may need to build a makeshift shelter is very valuable in an extreme cold survival situation. 
  4. Fuel: It is important to ensure your vehicle has as close to a full tank of gas as possible during the cold months as the ability to keep your heat running as long as possible is vital in an emergency.
  5. Maintenance: Just as the winter is hard on our bodies, it is also hard on our vehicles. Making sure maintenance is up to date will help prevent unexpected vehicle breakdowns in extreme cold conditions.

Build a Fire

Fire provides warmth, light, and so much more; having the ability to build a fire, especially one large enough to produce enough warmth to heat your body is very important. Wet conditions and high winds may make this task difficult. We always recommend keeping some water-resistant fire-starting material in your survival kits such as Black Beard Fire Plugs and ropes. With some practice, you can get a fire started with these tinder sources even in adverse conditions.

Treatment for Hypothermia

Even with all of our efforts to prevent hypothermia from occurring it is still very possible to succumb to it, or encounter someone else who is in a hypothermic state. These guidelines can help in an emergency situation, but it is still important to contact emergency medical professionals in the case that you or someone else is in a hypothermic state. 

-If possible, bring the person indoors, if not do your best to insulate them from the cold ground.

-Remove any wet clothing and replace it with warm dry clothing if possible.

-Rewarm the person focusing on their core using extra clothing and blankets.

-Do not warm extremities first (arms and legs) as this can cause arrhythmia (irregular heartbeat)

-Do not put in a warm shower or bath as this can cause arrhythmia.

-If conscious offer warm fluids, without caffeine or alcohol as they speed heat loss.

-If the person is unconscious begin CPR and contact emergency medical personnel immediately.