With this cold spell, I have had a lot of questions and visits to the ER with Frostbite and hypothermia.
Hypothermia occurs when a person’s core body temperature decreases to below 35°C/95°F. The onset can be subtle and creep up on the person. Hypothermia can occur in temperatures below or above freezing.
As tissues cool, their cells do not work properly: The brain and nerves work more slowly, muscles contract with more difficulty and may cramp more easily, and the heart becomes prone to fatal dysrythmias, (irregular beats).
As the core temperature drops, the body diverts warm blood into the core of the body (the trunk), allowing the arms and legs to become even colder. If the extremity tissue temperatures fall below 15°C (59°F), frostnip begins and can lead to frostbite. Drinking alcohol increases a person’s chances of developing hypothermia.
You can see the distinction between frostbite and hypothermia. You can stick your finger in a vat of liquid nitrogen, get frostbite but still not be hypothermic. Hypothermia refers to your CORE temp. (Best taken rectally, just as Tony prefers.)
For most cases of mild hypothermia, you can just use Passive External Rewarming. This is basically removing wet and cold clothes, getting warm blankets and sitting in a warm room. For more severe cases, you use Active External Rewarming, with warm IV fluids and warm water immersion. (You have to be careful about rewarming the extremities too fast in warm water, as the colder blood that is in the extremities can rush to the core and cause what is called Core Afterdrop. This is basically sending a bunch of really cold blood to the heart really fast and risking a fatal heart rhythm. In general, bad.) Finally, for extreme cases of hypothermia, (<30 C) you can use Active Core Rewarming, where you can put patients on cardiopulmonary bypass, stick tubes into their chest and abdomen and flush warmed saline in and out to warm the core. Gentle handling of severe hypothermia is warranted, as just bumping them the wrong way can send them into a deadly rhythm.
There is also a saying regarding hypothermia that no one is dead until they are WARM and DEAD. This basically means when someone comes in dead, like from an icy pond, you keep working on them until their body temperature is in the normal range, as patients have come back from brief periods of death in severely cold environments. Now get out there and enjoy the cold.