01/16/2024
Just for fun, I just did three laps of the parking lot with only a fleece gilet over my scrubs. The air temperature tonight is -27C (-17F), but with the 12mph winds that are blowing, it feels more like -39C (-38F). It wakes you up quickly that’s for sure, and it’s a great way to witness the miraculous adaptability of your body.
Every cell and system in our bodies is hard-wired to 1) survive, 2) reproduce and 3) maintain equilibrium (homeostasis). By exposing our bodies to cold shocks like this in a safe way, we force our bodies to adapt and overcome. If we are producing body heat at x rate sitting in the living room, by exposing ourselves to extreme cold, our bodies now need to start producing heat at y rate instead in order to maintain homeostasis. In other words, we increase the body’s metabolism. Doing this repeatedly over time increases our ability to burn fat as fuel, and increases the number of mitochondria in our muscle cells, the frying pan where that fat is burned.
As well as the extra fuel we burn, cold exposure also temporarily increases blood pressure and heart rate, in order to force the warm blood all the way around and back again. We breathe faster to increase our oxygen intake, and to load up those fast-moving red blood cells more efficiently. Our body hairs lie flat in order to trap a layer of warm air next to the skin. We shiver, which creates extra heat really effectively.
The normal body temperature we’re trying to re-establish is 37C – and remember that this is the internal body temperature, so don’t rely on foreheads or ear drums that have been out in the cold! These survival measures are pretty effective until the body reaches 32C. At that point it can no longer rewarm itself, no matter how hard it tries. As the core temperature falls, the brain’s executive functioning worsens, until it switches things off system by system, and eventually dies. But. There’s a saying in wilderness medicine, that you’re not dead until you’re WARM and dead! This is because until the core temperature drops below 24C, there’s still hope. The body falls into a kind of suspended animation – think Sylvester Stallone in Demolition Man – and can be reanimated by VERY careful rewarming (and other measures).
So, what does hypothermia (low body temperature) look like, and what can we do about it? (Remember that normal is 37C)
35 – 37C: Cold Stress.
Patients are conscious, shivering and they just feel really, really cold! Give them warm, sugary fluids to drink, get them moving about and protect them from the elements. Remember how we lose heat by conduction (touching cold things like the ground), convection (when cold winds steal your heat), respiration (by breathing with your mouth wide open), radiation (by being a hot body in a cold place) and evaporation (where your body tries in vain to warm cold water on the skin). So, get out of the wind, out of the cold, and change out of wet clothing. They’ll be right as ninepence in no time.
32 – 35C: Mild hypothermia.
Typically, they’ll be doing the umbles: stumbles, grumbles, fumbles and mumbles. Fumbling with zips, grumbling no matter what you do to help them, stumbling because they can’t walk probably, and mumbling because they can’t produce the fine movements needed for clear speech. At this point moving them becomes dangerous because they’re so clumsy, so we lie them down off the cold ground and apply heat pads to the neck, chest, back, arm pits and groin. Do not give fluids or food unless they are completely conscious and there is no risk of choking. Wrapping them up like a burrito really helps!
