Often a misunderstood hazard in the outdoors because it has a tendency to sneak up on us, frostbite is defined as the actual freezing of human tissue. Most often it’s a combination of cold temperatures (temperatures must be below freezing), wind, and moisture. It occurs most often in the feet or more precisely the toes as a result of cold wet feet in tight boots (i.e. poor circulation).
Some of the other common sites are the exposed extremities of the ears, face and nose. It can happen in the hands and fingers, but not as often as you would think because of our ability to easily place our hands in a more environmentally friendly area. Even though the fingers are similar to the toes with limited circulation and mass, the hands are more prone to contact and flash frostbite than prolonged exposure.
There are 3 major causes of frostbite
1. Prolonged Exposure (the most common cause): This is the one we traditionally think of and it’s brought on by prolonged exposure to cold temperatures, hence the name. Usually wind and water are also factors in the equation.
2. Direct Contact: This is when skin contacts cold metal and freezes upon contact. The movies have had fun with this one, such as when a certain person decides to put their tongue on a pole and sticks.
3. Flash Frostbite (the nastiest one): This one occurs when you spill cold fuels on exposed skin at sub-zero temperatures. We’ve chemically designed fuels to not freeze so we can work and use them at sub-zero temperatures. The only downside is that if spilled on the skin they will literally eat through the skin.
There are 3 major types of frostbite
1. Superficial: Known as frostnip, it’s where the first layer of the skin is frozen and is very similar to a superficial burn or sunburn. The skin turns red and can peel.
2. Partial Thickness: Considered true frostbite where the skin often looks white, waxy and moldy, it involves the first two layers of the skin. If you push on the skin it may dent and the dent will linger. When re-warmed this type of frostbite often forms Blebs, a fluid filled blister that’s the bodies way of fighting dehydration. Note: if the blebs are clear damage is minimal, if they are dark damage is more severe and tissue loss is highly likely.
3. Full Thickness: This form of frostbite is where it involves all three layers of the skin and even muscle and bone. Often characterized by a wooden sensation or numb and colorless, this form of frostbite is severe with amputation highly likely.
So how do we treat frostbite?
Because frostbite is the actual freezing of tissue, what happens are crystals form in the fluid between cells which draws fluid out of the cells and then dehydrates them. As the body part re-warms the crystals then evaporate resulting in vasoconstriction and further dehydration. Because there are crystals we never want to rub frozen body parts, so as not to slice and dice or do damage internally.
For frostnip one of the best ways to re-warm is skin to skin contact. That could be placing your hands on your ears, fingers in your armpits or feet on someone’s belly (not the easiest proposition to make).
For partial thickness frostbite the best method is to soak the frozen part in 100 to 105 degree water until thawing is complete. Soaking helps minimize the damage from dehydration. Thawing is complete when color and sensation return. The skin will usually look red and blebs will often form. Note: keeping the water temperature constant is important but difficult with a frozen body part in the water, so do your best.
For full thickness frostbite thawing can be done in the same way as partial thickness. This is a very painful process and care should be taken not to allow the person to use the thawed body part until a doctor has checked it out. It is extremely bad to refreeze a body part; it will completely destroy the tissue and guarantee amputation. The thought in the medical community is to insulate and keep it frozen until you can properly treat it without the chance of refreezing.
So how do we prevent frostbite? As the saying goes prevention is the best medicine, so here’s a nice list to remember:
1. Use the buddy system. Have a friend keep an eye out for any signs of frostbite.
2. Wear proper cold weather clothing, including rain and wind gear, mittens and boots.
3. Avoid tight fitting clothes that constrict blood flow, especially boots.
4. Monitor your feet for moisture.
5. Stay hydrated and maintain calories in order to produce proper metabolic function and circulation.
6. Reject tobacco, it greatly increases your chance for frostbite.
7. Avoid contact with cold metals or fuels by wearing gloves or mittens when handling such items.
8. Condition your hands and feet for the cold by using a moisturizer. Pliable skin resists freezing more than dry skin.
About the Author:
Greg Rouse has been teaching wilderness sports and emergency response at the university and college level for over a decade. He is also the founder of a unique web site called WildernessTrip.com, a one-stop resource for self-guided wilderness trip planning. This web site is basically; a free online guidebook that photo-documents trips with interactive maps and detailed route descriptions. Each trip has free pictures and free topographic maps of the trail, all in a print-friendly format. Check it out at http://www.WildernessTrip.com