Tuesday, December 2, 2014

In Winter, Frozen Isn't Just A Disney Movie

Winter came early to a huge portion of the United States in 2014. Cold temperatures, slick roads and wind were the found in many places in mid-November. Heck, parts of Buffalo disappeared for more than a weekend.

Frozen is based on a Hans Christian Andersen tale called
The Snow Queen, written in 1844. In Andersen’s story,
there is an evil mirror that only reflects the bad in
something, none of the good. That’s like this post – we
talk about how winter cold can harm, not how it can
bring two sisters together and heal a broken kingdom.
It’s the cold temperatures that are the source of so much misery. A storm in the North Pacific changed the flow of the jet stream, and freezing temperatures dipped low into the US. People had to take measures to avoid freezing to death – literally.

Low temperatures can kill a person in a couple of ways. Frostbite is the freezing of parts of the body. Your cells are mostly water; when water freezes it forms crystals. The crystals are sharp and are larger than the same amount of water (ie. water expands when it freezes). This leads to punctures in the cell membranes; the affected parts of the body sort of digest themselves due to the release of enzymes from the broken cells.

Frostbite usually affects the extremities - toes, fingers, nose, ear lobes, private parts for men - because they have less blood flow and are harder to keep warm. Your body also sacrifices these body parts in an effort to keep warm by constricting blood vessels to keep the majority of blood from cooling and carrying the cold back to the center of the body.

Reduced blood flow is usually the reason for frostbite; less blood in the area means less heat, which means a greater risk for freezing. The reduction could come from physiologic vasoconstriction, or from underlying medical conditions that result in poor circulation. For instance, people with diabetes have poorer circulation and are much more susceptible to frostbite.

We add salt to the streets to lower the freezing temperature
of water. But on your skin, salt and ice lead to rapid frostbite.
The first person to try the salt and ice challenge could be
forgiven, but for anyone who has seen the videos of the
aftermath and still tried it – I have no sympathy for you.
Areas that undergo frostbite can sometimes be saved by the  infiltration of new blood vessels (angiogenesis) and the replacing of the dead cells. But if freezing of deeper tissues (muscles, tendons, bones) has occurred, this will probably not be possible. If larger/deeper areas are involved or if there is infection, amputation could be necessary. If no treatment is rendered – a person could actually die from the toxins released by an infection or from the dead tissue.

Interestingly, many sources of frostbite information state that if you are going out into the cold, you shouldn’t drink alcohol or smoke (tobacco or marijuana), as they can predispose you to frostbite. A 1997 study of blood flow in acute smoking showed that peripheral blood circulation was decreased from the moment smoking began. A 2008 study extended this to second hand smoke as well, showing that nicotine impairs microvascular function.

Marijuana gets a double hit, since it lowers blood pressure AND vasoconstricts the peripheral vessels. This is bad news for Colorado; legal pot and lots of cold weather. Likewise, drinking alcohol immediately before going out in the cold is dangerous because it is vasoconstrictive immediately after ingestion.

There’s a potential new problem in frostbite. With the
increase in solid organ transplants, it is becoming more
evident that some organs are being transported at too
low a temperature and they are being damaged. A recent
study examined frostbite in a liver to be transplanted
into an 18 month old.
On the other hand, the same cold temperatures that lead to frostbite can also kill you directly. Hypothermia is the bone-chilling cold you feel when your entire body’s temperature is dropping. Your normal body temperature is 98.6 ˚F (37 ˚C) or thereabouts. At 95 ˚F (35 ˚C) hypothermia begins. At 91 ˚F (32.7 ˚C) you get amnesia, and below 85 ˚F (29.5 ˚C) you lose consciousness. Now you’re in trouble.

Hypothermia can kill you in several ways, two of which have to do with electricity. Your heart beats because it supplies itself with a chemico-electrical jolt every second or so. This is what occurs in the sinus and AV nodes of the heart and is based on an electrical charge difference across the cells' membranes in the node.

Low body temperature messes with the membrane potential, so the heartbeat is slow and erratic. Too slow (bradycardia) or too erratic (arrhythmia) leads to a heartbeat so dysfunctional that it won’t push the blood through your body and you die from cardiac failure.

Electrical messaging is also how your central and peripheral nervous systems work. Not only does cold temperature slow the nerve impulse by altering the membrane potential, but it also slows the transfer of the signal from one neuron to the next. The neural synapse is the gap between two or more neurons and relies on chemical messages (neurotransmitters) released from the upstream neuron to trigger and electrical signal in the downstream neurons.

Cold temperature slows the release and/or reuptake of the chemicals in the synapse, so brain function is altered. This explains the confusion many people experience in hypothermia and the “paradoxical undressing” that victims often carry out.

That’s right, people who are so cold as to affect their brain activity often strip right there in the cold. It seems that as the small muscles that control vasoconstriction in an effort to prevent hypothermia will finally fail after working for a long time.

In some cases, lowering the body’s temperature radically is
beneficial. Originally called therapeutic hypothermia, the
technique is now more controlled and is called target
temperature management, as reviewed in this late 2014
publication. Lowering the body’s temperature for a short time
is effective in preventing some of the damage done by
cardiac arrest or stroke.
This creates a short vasodilation that brings a burst of relative warm blood to the skin. The victim may feel a hot flash, and in his/her altered neurologic state might take their clothes off to cool down. I saw no fewer than 16 cases based on just a cursory literature search.

Finally,  our proteins have evolved to function best when they are held at 98.6 ˚F. One could ask, did the protein conformation (its folded shape) evolve because of our temperature, or did our temperature evolve because our proteins fold a certain way? In either case, every protein’s function is based on its conformation, and the folding and shape are dependent somewhat on temperature.

Lower your body’s temperature and the proteins’ shapes will change. When this happens they don’t work so well, and this throws off your entire physiology and metabolism. Throw it off too far, and there’s no coming back.

Next time we talk together - what can a person do to avoid frostbite and hypothermic death? Stay out of the cold by moving to Florida or buy every warm piece of clothing North Face offers. These are ways humans overcome the environment, but there are also physiologic ways our bodies can combat the cold.

contributed by
Mark E. Lasbury, MS, MSEd, PhD
As Many Exceptions As Rules

Palmers PJ, Hiltrop N, Ameloot K, Timmermans P, Ferdinande B, Sinnaeve P, Nieuwendijk R, & Malbrain ML (2014). From therapeutic hypothermia towards targeted temperature management: a decade of evolution. Anaesthesiology intensive therapy PMID: 25421924
Argacha, J., Adamopoulos, D., Gujic, M., Fontaine, D., Amyai, N., Berkenboom, G., & van de Borne, P. (2008). Acute Effects of Passive Smoking on Peripheral Vascular Function Hypertension, 51 (6), 1506-1511 DOI: 10.1161/HYPERTENSIONAHA.107.104059
Adams MD, Earnhardt JT, Dewey WL, & Harris LS (1976). Vasoconstrictor actions of delta8- and delta9-tetrahydrocannabinol in the rat. The Journal of pharmacology and experimental therapeutics, 196 (3), 649-56 PMID: 4606
Morioka C, Kondo H, Akashi K, Matsumura K, Ochi N, Makinaga G, & Furukawa T (1997). The continuous and simultaneous blood flow velocity measurement of four cerebral vessels and a peripheral vessel during cigarette smoking. Psychopharmacology, 131 (3), 220-9 PMID: 9203232



  1. Any connection between hypothermia and waterboarding?

  2. Disney movies always follow the formula of Happily Ever After, and it always works. If people didn't want to see the hope of a happy ending, they wouldn't play frozen games online and see movies to escape the every day.