Avoiding Dangerous Frostbite

By Gabe Mirkin, M.D.

You should never suffer from frostbite: painful freezing that can cause permanent loss of skin, and can be followed by loss of fingers, ears, toes, or even arms and legs. You get plenty of warning before your skin starts to freeze. First your fingers feel cold and then your skin starts to burn or itch. That means that your skin temperature, which is normally a couple degrees below your internal body temperature of 98.6, has dropped low enough to drop your internal body temperature.

Your brain notices this drop in body temperature and tries to preserve heat by sending a message to the nerves in your hands and feet to close the blood vessels there. With decreased blood flow, the skin temperature of your hands and feet drops rapidly. When your skin temperature reaches 59 degrees Fahrenheit, your brain sends signals to open up the blood vessels in your hands, causing your fingers to turn red, burn and itch. This is called the “hunting response” and is normal. (If you have chronically cold hands that turn white and hurt whenever they are exposed to temperatures below 60 degrees, you may have a condition called Raynaud’s phenomenon because you do not have the normal “hunting response.”)

You should seek warm shelter immediately when your hands or feet turn red and start to itch and burn. If you don’t get out of the cold, the blood vessels in your hands and feet will close down again and the temperature will drop even more rapidly to below freezing. The progressive signs of frostbite are:
• skin feels cold
• numbness
• burning, itching or a feeling of pins-and-needles
• skin turns red
• then skin turns blue and then white
• blisters can form as the tissue dies to release fluid from its cells

Note that if you have dark skin, you may not see color changes, but you will feel the other symptoms of impending frostbite.  The skin on your palms is likely to turn white even if color changes do not show on other skin areas.

Preventing Frostbite

You feel pain from the cold first in your fingers, ears and toes. During World War II, gunners on bombers complained bitterly about frozen hands, ears and feet, so special insulation was added to their gloves, hats and boots. They stopped complaining, but then they suffered frostbite on their necks and chests because they didn’t feel cold as much there.

Hands: Wear an inner layer of thin gloves made from loosely-woven material that permits sweat to pass through. You may need a middle layer of a more tightly woven-thick material, and if it is very cold, an outer layer that does not let wind or water in. If you don’t need extra hand dexterity, you should wear mittens. The single compartment of mittens retains heat better than gloves that have separate compartments for each finger. You can also buy hand warmers to be used inside your gloves or mittens. They may be:
• iron that is air-activated, lasting for up to 10 hours and not reuseable
• crystallization types that can be reused (follow the package directions for reheating)
• electric types that can be cumbersome because they use batteries and wires

Ears and Head: Cover your ears with a headband or wear a balaclava that covers your head and neck and has an opening for your eyes, nose and mouth.

Feet: Avoid cotton socks because cotton holds water, while wool and various synthetic fibers do not. On very cold days, wear layers of socks. Cyclists, skaters and skiers may want to add windproof and waterproof booties that are designed to fit over their special footwear. If cold feet still make you miserable, you can get the same types of warmer packets as the hand warmers described above, shaped to fit in your shoes or boots.

Body, Arms and Legs: Use layers of clothing because the air space between layers provides insulation from the cold. You generate a lot of heat when you exercise, so use full length zippers on your outer layers so you can adjust to your changing needs. By wearing several layers, you have the option of removing layers or unzipping the fronts. The base layer should wick away sweat, so use fabrics made from wool blends, silk or synthetics.

Cotton is a poor choice because it holds water. The middle layers should be breathable and provide insulation. Loosely woven wool or synthetic sweaters or vests are a good middle layer because they trap insulating air and wick water to the outside. The outer layer should be of a material that blocks wind and rain, with a full-length zipper so you can remove it easily when you don’t need it.

Emergency Treatment of Frostbite

If you feel excessive cold or pain in your fingers, ears or toes, get to a warm shelter as soon as possible. If you have blisters, broken skin, severe pain, signs of infection, no feeling in your skin, or skin that remains white, seek medical help immediately. You can lose fingers, ears and toes and even your life. Mild frostbite (when you still have feeling, the skin is not broken and normal color returns to the skin) can be treated with rewarming in comfortably warm (not hot) water and drinking warm fluids. Frostbite with any broken skin or blisters or feeling that does not return to the frostbitten area should always be checked by a doctor. Frostbitten skin can be destroyed and the blood supply to an arm or leg can be shut off permanently to cause loss of arms or legs, or an infection can spread through your body.