Frostbite is a medical condition caused by exposing skin to extreme cold. I've mentioned it a few times while
writing about cryogenic gasses (anhydrous ammonia and liquid propane gas), so
it's not an exclusively a winter-time threat, but during winter exposed
areas like fingers, toes, ears, noses, cheeks, and chins are the
most commonly affected areas.
Where fire and heat damages tissue like skin by cooking it, frostbite damages it by freezing. If skin gets too cold, the tissue under it will start to freeze, causing the cells to burst as the water that makes up 60-70% of each cell expands. Further damage is caused by the loss of blood flow to the frozen tissue, leading to tissue death (necrosis). This can cause damage ranging from irritation to amputation, similar to burns. Like burns, frostbite has been broken down into three levels or degrees.
Where fire and heat damages tissue like skin by cooking it, frostbite damages it by freezing. If skin gets too cold, the tissue under it will start to freeze, causing the cells to burst as the water that makes up 60-70% of each cell expands. Further damage is caused by the loss of blood flow to the frozen tissue, leading to tissue death (necrosis). This can cause damage ranging from irritation to amputation, similar to burns. Like burns, frostbite has been broken down into three levels or degrees.
Level 1
- Numbness and loss of movement or dexterity
- Skin may also turn red, similar to a 1st degree burn
Treatment is simple: gently warm the
cold tissue to restore proper blood flow and keep it warm until
normal functions are restored. Placing the affected body part into
warm (not hot!) water works well. Hot water won't work because your affected parts won't be able to feel the temperature properly, and if the water is
too hot you can cause extra damage. If warm water is not available,
add insulation to the affected body part and increase your physical activity to warm it from
the inside with increased body temperature and blood flow. As the
tissue warms up and nerves are reactivated, you're going to feel a
lot of pain. It's going to feel like the affected tissue is on fire
and you're going to want to stop the warming. Keep it up until things
start to feel normal again.
Level 2
- Skin is hard to the touch and white or waxy looking
- Fingernails and toenails of affected area will no longer show capillary refill
- Blisters and peeling skin, similar to a 2nd degree burn, are common
Capillary refill is a simple check: Press down on the nail -- it will go white as you squeeze the blood out of the capillaries -- then release. Normal blood flow will return the pink color in less than a second, but reduced or stopped blood flow will cause them to stay white.
Treatment is similar to Level 1, but
will take longer and needs to be monitored more closely for signs of
necrosis. Hands and feet are easy to warm by placing them under your
or another's armpits. Think of the places where you sweat the
most, and those are the areas that tend to be the warmest; the armpits and crotch are the easiest to access. Shared body heat can be
a medical treatment, so two or more naked people sharing a sleeping
bag might not be what you think.
Level 3
- Skin has turned a darker color and is as hard as ice
Treatment at this level requires medical training and equipment, so get the injured person to a hospital. My opinion, and I am NOT a doctor, is that frozen tissue is dead and I wouldn't want to restore blood flow that could pump dead or damaged blood cells back into the rest of the body unless I had antibiotics, blood thinners, and other measures at hand. I'd leave frozen tissue frozen until treatment was available,while keeping other areas from freezing.
Prevention
Frostbite
hits the young and old the hardest because they have a hard time
controlling their body temperature. Use of alcohol, tobacco, and a
lot of medications that limit blood flow will make you more
susceptible to frostbite. Dress in layers, cover your ears, face, and
extremities, and keep an eye on your friends and family. It's hard to
look at your own ears and face, so you can develop frostbite and not
know it until someone else points it out.