Have you ever been so cold that your skin has turned white in places? If you have then you've experienced frostbite. Frostbite usually affects nose tips, cheeks, ears, fingers and toes. It occurs with exposure to cold, combined with a lack of the blood to circulate heat. Once the area is affected, a lack of oxygen causes damage to the tissues.

There are two types of frostbite superficial and deep. The onset of frostbite is painful, but is often overlooked since the nerves eventually freeze causing numbness. If the part is painfully cold, then suddenly stops hurting when obviously not getting warmer, frostbite should be expected. It's important to watch these areas of exposure in your companions.

Superficial frostbite will usually appear yellow or grayish. The underlying tissue will still be soft and pliable. It can generally be cured by putting the injured area in direct contact with warm skin, such as the armpits or abdomen. Thawing the part will help restore circulation. Putting cold fingers under a neck gaiter at the base of the neck also works well.

Deep frostbite is much more serious. It usually affects the hands or feet, and may eventually lead to the loss of an extremity, if not cared for properly. When tissue is frozen deeper, the underlying tissues become solid and wooden. The tissue will likely turn brown and blister on the surface, as well as underneath. The skin is white and waxy or chalky in appearance. Frostbite, especially blisters should not be treated by rubbing with the hands or snow! Otherwise, damage will be much worse! Rapid rewarming is advised, because it leaves less damage.

The decision to thaw an extremity in the backcountry should be measured by two things. First of all ask, could the injured part become refrozen? If the extremity is thawed then refrozen, it will lead to gangrene. Secondly decide how the patient will be evacuated, because thawed tissue should not be used or walked on.

If a helicopter or sled rescue is possible, then thaw the part as soon as possible to reduce damage from an extended period of oxygen deprivation. Avoid allowing the extremity to slowly thaw out spontaneously during a walk out. If the only way out is by having the patient walk, snowshoe or ski, keep the extremity frozen or wait for help.

If providing first aid in the field with deep frostbite, a shelter will be needed. An igloo or ice cave would be great if already built. Otherwise, a tent would be much faster and easier. If no tent is available, find a natural wind block, use tarps and know how to make an emergency shelter before venturing out.

When treating frostbite, use a stove to heat water to a controlled 102-108 degrees F, which is hot like the temperature of a Jacuzzi, but you can still place a hand in it. Do not use a fire or really hot water, because the tissue will be burnt. If the water becomes cool, remove the injured part then add hot water and stir, until the required temperature is regained. Be sure to test the water. Use a pan that is bigger than the extremity, so skin is not touching the sides. While rewarming give the patient hot drinks to improve morale and apply heat packs to non-frozen areas to improve circulation. The affected area should become a deep red or bluish color, when thawed. Expect the procedure to take about 20-30 minutes.

After thawing use sanitary dressings to soak up heavy drainage from blisters. Although blisters will be very painful to the patient do not break, scrape or rub them, because it will cause more damage and once open they may become infected. Separate digits with soft cotton. Also, elevate the extremity to increase circulation. Continue to wrap in a thick bandage and protect it from further injury.

To prevent frostbite any time of year, wear layers of clothing that wick sweat away from the body, as well as insulate. Then use shells that protect from wind and precipitation. The clothing should not be tight. Choose footwear suitable for the activity and use socks made with synthetics or wool as opposed to cotton. Gloves, mittens and glove liners should be worn throughout the day. A fleece hat and neck gaiter or scarf must be worn to reduce 40 percent of heat loss. Then place a windproof hood over the hat for extreme weather.

By taking these precautions the nose tips, cheeks, ears, fingers and toes will have a much lower chance of being affected. Once frostbite occurs, rapidly rewarm the frozen extremity as soon as possible, by placing against warm skin for mild cases or use hot water for deep frostbite. Plan ahead for evacuation and do not allow the damaged tissues to be used or refrozen. Carry a first aid kit to bandage the affected areas and protect them. Then take the patient into the hospital as soon as possible.