Frostbite

Frostbite is nothing more than frozen tissue in the body.

Water freezes at 32F/0C–the temperatures that cause frostbite need to be lower than that.
We are mostly water, but it is slightly salty, so it takes a lower temperature to freeze the tissues in the body.

The longer the exposure to the cold and the colder the ambient temperature determines how deep the freezing goes. Think of it like the frost line in the ground; in some places, it goes down four feet, and in others, it barely goes more than a few inches.

When tissue freezes, the water in the cells expands. This freezing can stretch the blood vessels (which are also less pliable in the extreme cold) and lead to these vessels’ rupturing. Freezing water inside a pipe expands when frozen and causes it to break–as it thaws out, the water will begin to flow again and leak. The same thing happens to our blood vessels–as the tissues thaw, the ruptured blood vessels will leak into the surrounding tissues.

Prevention

Prevention is as simple as increasing the production of heat and retention. Remember, water can’t freeze if it is warm. The best practice to prevent frostbite is, like all cold injuries, to catch it early.

Signs and Symptoms

Superficial frostbite does not involve deep tissues–it remains in the outer layers. The tissue is somewhat pliable but stiffening. The tissue will be pale (or starting to turn “blue”), and the sensation will be significantly reduced.

Deep frostbite is when the tissues are frozen solid through all of the layers. There will be no sensation in the affected area. The tissues will also be white or bluish, and you may see ice crystals on the surface.

Treatment

Superficial frostbite can be thawed–the best way to do this is to warm the entire patient. Protect from the cold, feed the patient, and get them moving to generate heat.

Ideally, deep frostbite is rewarmed in the hospital. You can not let the tissue refreeze. Refreezing causes more damage to already damaged tissue. It is better to leave the tissue hard frozen for several hours than to risk refreezing.