Mad About Science: Hypothermia

By Brenden Bobby
Reader Columnist

That season Ned Stark all warned us about has finally come. I write to you now with fingers shivering, teeth chattering and a mug of iced tea that was piping hot a few minutes ago. When you find this edition Reader, gripped tight in my frozen clutches, tell my family… that I wished I had actually finished The Witcher 3.

Despite our incredible resilience as a species, we’re delicate little flowers when it comes to temperature fluctuations — especially in the cold. Once our internal temperature drops below 95 degrees Fahrenheit, bad things start to happen and we begin to suffer the onset of hypothermia.

Our body’s thermometer is a part of our brain called the hypothalamus. It tells us when it’s time to sweat, when it’s time to shiver, when it’s time to curl up, and when to start cutting losses and sacrificing digits for the survival of the rest of the body. Your hypothalamus is so important that damage to it can cause a chain reaction in your brain leading to hormonal imbalances, weight gain or loss, sleep deprivation, dehydration, lactation and the inability to maintain your body’s internal temperatures.

Let’s say your hypothalamus is perfectly healthy as you’re reading this paper and not sweating out of your eyelids, but you’re still shivering in January. Though minor, shivering is the first stage of hypothermia. Your body is losing heat faster than your metabolic system can produce it, so your hypothalamus is turning on the auxiliary power: triggering your muscles to spasm and shiver to generate extra heat. Under normal conditions, this is perfectly fine — if not mildly inconvenient — until you can find shelter.

If you’re in the cold for an extended period of time, and your body is still losing heat faster than it can produce it, your core temperature will begin to drop below a comfortable 98.6 degrees Fahrenheit. Your body will begin to start pulling blood away from your skin, which normally acts similarly to your car’s radiator, providing a large surface area exposed to cool air that will allow heat to radiate away. This redirection of blood flow begins to affect your nerves, depriving them of oxygen and causing a numbing sensation in your fingers and toes.

If your ears, fingers and toes go too long without a blood supply, the cells will begin to die. Not only will they die, but the water within the cells will freeze and crystallize, which causes permanent damage. In extreme cases, the affected parts of the body will become gangrenous, which means the flesh has died and will often turn red or black. At this point, there’s no saving that body part, and it’s often amputated to prevent a greater infection from entering the body through what is essentially a gaping wound.

The final stages of hypothermia occur when your internal temperature drops so low that your body starts taking the blood away from your organs, in hopes of preserving the heart and brain long enough for help to arrive, though usually it’s too late for help once this occurs.

Recovering from extreme hypothermia isn’t as easy as getting indoors or sitting next to a fire. Once frostbite has set in, the body must be carefully re-heated, usually on its own. Applying heat to frostbitten areas can lead to permanent damage and intense pain: the frozen water in your cells is literally melting back into a water state, and the blood is reoxygenating nerves that are potentially damaged.

Patients suffering from extreme hypothermia are dried off and bundled in as much insulation as possible, keeping cold air away from the body while allowing the heat to stay trapped within the body. Water present in the clothes or skin pulls heat out of the body far more quickly than air, and is the leading cause of hypothermia-related hospitalizations around the world. 

Ironically, as damaging as cold is, it can be used as a means to postpone death. Anesthesiologists may use a technique called deep hypothermic circulatory arrest, or DHCA, to effectively freeze a patient, stop their flow of blood and allow surgeons to operate on the patient for up to 40 minutes before having to worry about inflicting permanent brain damage. Generally, this type of procedure is used on patients that have some sort of problem with their heart such as certain cancers, where they must be placed on bypass for an extended period of time.

This technique is similarly used in cryonics, mistakenly referred to as cryogenics, which is a practice whereby people are frozen after death as a means of preservation for a possible future cure for whatever is killing them. In these instances, the person being frozen is exsanguinated, and their blood is replaced with a freezing slurry, which prevents the cells from crystallizing and negates the dangers of frostbite, should science ever find a means to resurrect them.

Weirdly, you can get a discount through most companies if you let them decapitate you and only freeze your head, letting you pay studio apartment rent for your loft, as it were.

If this article sent a shiver through you, let me be the first to remind you that the library has a functional fireplace on the second floor.