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It's common sense to find a warm place to warm yourself up after being cold, right? However, for people who are freezing to death, we can't do it so simply and rudely, because it will kill them. Today we will introduce this anti-common sense knowledge of first aid.

The people we are talking about freezing to death are not people who are normally exposed to cold. Medically, they belong to people with hypothermia, that is, people whose body temperature is less than 28 degrees Celsius.

For people with hypothermia, taking a hot bath may make them on the spot. This is because of a phenomenon that has not yet been fully understood-post-hypothermia (afterdrop).

Post-hypothermia means that after the loss of body temperature, even in a warm environment, the temperature of the body's internal organs, that is, the core, will continue to cool for 10-30 minutes before heating up.

The core temperature of a person's body is always higher than that of his limbs. (photo: wikimedia) people who have swam will have this experience. For a period of time after climbing out of the pool, instead of feeling warm, you will continue to shiver, which is caused by the drop in body temperature.

In fact, the visceral temperature continues to drop 20-30 minutes after coming out of the pool. Mike Tipton, a physiologist at the University of Portsmouth in the UK, and colleagues said that after getting out of the swimming pool, even if the body had been dried, the core temperature would drop by up to 4.5 degrees Celsius.

(photo Source: Internet) for healthy people, they can still bear the cold in their chest. For people with hypothermia, however, it can be fatal. Because low temperature changes the electrical conductivity of the heart, arrhythmia and atrial fibrillation can easily occur when the core temperature is below 32 degrees Celsius, which can lead to death.

Because of the risk of death after hypothermia, the official guidelines of the Wilderness Medical Association (Wilderness Medical Society), the largest field rescue society in the world, have special guidance on hypothermia. For example, when helping people with frostbite, they usually don't keep them too warm. Also because of the drop in body temperature, winter sports are more dangerous than summer sports.

(photo Source: pexels) but why does hypothermia occur?

Before the 1980s, the mainstream view in the medical profession was that the drop in body temperature was the pot of the human circulatory system.

The emergency medicine textbook at that time explained that when a person felt cold, the natural response of the human body was to constrict the blood vessels of the limbs, thus allowing blood to flow back from the limbs to the vicinity of the viscera to prevent the visceral temperature from further decreasing. And because the temperature of a person's limbs is very low, warming his limbs will cause vasodilation of the limbs, which is equivalent to bringing cold blood home, which can cause a sudden drop in heart temperature and sudden cardiac arrest.

This view also directly affects the rescue of patients with hypothermia. For example, when treating patients with loss of temperature with warm water in the bathtub, emergency medicine textbooks recommend not to soak the patient's hands and feet in hot water, but to expose them to the surface of the water. Whether hypothermia occurs in patients with hypothermia or not is even used to measure the effect of rewarming.

But then there was a lot of evidence to refute the circular theory.

For example, some experiments have found that small mammals such as mice and rabbits do not experience hypothermia, but the remains of dead pigs do. In addition, slow hypothermia is less likely to cause a drop in body temperature, but a rapid drop in temperature is often accompanied by a drop in body temperature.

(photo source: Internet) A study published in 1986 in the Journal of Applied Physiology (Journal of Applied Physiology) dealt a blow to the circular theory.

In this paper, researcher Paul Webb conducted a series of experiments using cow legs and bags of gelatin to simulate the human body.

(photo source: wikimedia) he found that cow legs and gelatin also showed a drop in body temperature.

In addition, he also found that when the body cools quickly and then heats up, the rectum, ear canal and esophagus all have a drop in body temperature. However, if the temperature returns after a period of time, or the cooling rate is relatively slow, there is generally no drop in body temperature.

Mike Tipton mentioned above experimented with melons. He found that after the melon was taken out of the ice water, its central temperature continued to drop.

(photo Source: wikimedia) these experiments show that the drop in body temperature may be a physical phenomenon related to heat conduction, not necessarily related to the circulatory system of the human body.

However, there is something wrong with the theory of physics. In 2015, Douglas Brown, a researcher in emergency medicine at the University of British Columbia and colleagues, pointed out that in fact, researchers do not know why some patients with hypothermia are fine after warming up, but others continue to lose temperature after keeping warm until cardiac arrest. If post-hypothermia is a complete physical phenomenon, why does it not occur in some patients?

In any case, in order to avoid the risk of hypothermia, some new treatments have emerged, such as directly drawing blood out of the body for heating (that is, cardiopulmonary bypass (Extracorporeal venovenous rewarming). After using these more powerful but more painful invasive rewarming (invasive rewarming) methods, a person's organs can be heated at the same time, making it less likely that the body temperature will drop later.

If you think about it, it's really scary to have a drop in body temperature. A person may not freeze to death in the ice and snow, but die of the warmth after the severe cold.

Cold knowledge: the little match girl died not from the cold in winter, but from the warmth of matches.

Reference:

Https://docs.qq.com/doc/DVFBraXN3YU56V1B4

This article is from the official Wechat account: bring Science Home (ID:steamforkids), author: everything.

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