Death from hypothermia is not just in winter, nor is it just outdoors.

Hypothermia is a potentially life-threatening medical emergency. If you experience hypothermia, seek medical attention immediately.

Written by | Idobon

On May 22, the Gansu Province Yellow River Stone Forest Mountain Marathon 100km cross-country race encountered extreme weather. Hail, freezing rain, strong winds and other disastrous weather occurred on some parts of the track. The temperature dropped sharply and 21 participants unfortunately died due to hypothermia.

Hypothermia, or low body temperature, refers to a person's core body temperature falling below 35°C. The so-called core temperature refers to the temperature required for the deep organs of the human body (such as the heart and liver) to maintain operation. This is a concept relative to the temperature of peripheral tissues. The range of core body temperature is very narrow. Within this range, the human body can undergo enzymatic reactions necessary for survival. When the human body is in a cold state for a long time and the core body temperature drops to a dangerous level, it faces hypothermia.

Modern society has long since left behind the days of people freezing to death on the streets. When people think of hypothermia and freezing to death, they often think of accidents. For example, being immersed in the icy sea, being stranded in the freezing wilderness, and the extreme weather encountered in the Gansu Wild Marathon. But in fact, in daily life, everyone may face the risk of hypothermia and being "frozen to death." According to official statistics from the U.S. CDC[1], from 1999 to 2011, an average of 1,301 people died each year from hypothermia-related symptoms. Of course, most hypothermia occurs outdoors in the cold winter, but if the conditions are met, people may also suffer from hypothermia in indoor environments where the temperature is not too low.

If you soak in the cold sea, you will freeze to death. 丨Image source: Stills from the movie TITANIC

When the body's heat supply is less than heat loss for a long time, the body temperature will continue to drop, resulting in hypothermia. It can be seen that under normal circumstances, the ambient temperature itself is not a key risk factor for hypothermia. For example, in the summer, when you come out of the swimming pool, you are soaking wet, and a gust of wind blows, you will feel very cold, and even get goose bumps. If the indoor temperature is not set enough, hypothermia may also occur. After the elderly fall and lie on the cold floor, the heat will also be lost quickly.

There are many risk factors for hypothermia, mainly in the following categories:

Age: Children and the elderly are more susceptible to hypothermia because their body temperature regulation ability is weaker. Among them, the elderly are the most vulnerable group to hypothermia. In the United States, deaths related to hypothermia are closely related to age.

http://www.nia.nih.gov/NewsAndEvents/PressReleases/PR20050118Staying.htm

Diseases: Dementia, underactive thyroid gland (hypothyroidism), low blood sugar, and high blood pressure may cause hypothermia.

Medication: Some medications increase the risk of hypothermia, such as barbiturates, antidepressants, and tranquilizers. Blood pressure medications can inhibit the body's response to cold, so older people taking blood pressure medications should pay more attention to keeping warm.

Dehydration: After dehydration, the body's blood volume decreases, the body dissipates heat faster, and may cause hypothermia.

Intense exercise: Some athletes lose heat easily due to excessive sweating, dampness of the body, and extreme fatigue.

Drinking: Drinking alcohol causes blood vessels to dilate, but it actually causes the temperature to drop faster.

Hypothermia can be divided into several stages, depending on its severity:

In the article “What Really Happened in the Yellow River Stone Forest 100km Cross-Country Race” [2], which details the entire course of the May 22 accident, the author, as an eyewitness survivor, describes the process of hypothermia.

"When the race started, many of the great players were wearing short-sleeved shirts and shorts. They were trembling as they waited for the start, but when the gun went off, they rushed out like arrows."

At this time, everyone's body temperature is already very low and everyone feels cold. They hope to warm up their bodies by running.

"My whole body was soaked, including my shoes and socks. The wind was so strong that I couldn't stand up. I was very worried about being blown down. The cold was getting unbearable, so I found a relatively sheltered place, took out a thermal blanket, and wrapped it around myself. But it was blown away by the wind in an instant. It was of no use."

The thermal conductivity of water is 32 times greater than that of still air. At the same temperature, the rate of heat loss in water is 32 times faster than in still air. The human body loses heat 25 times faster when wearing wet clothes than when wearing dry clothes. If there is wind, the "wind chill effect" will occur, which is the phenomenon that the perceived temperature is lower than the actual air temperature due to wind. [3]

Being soaked all over and with strong winds, one can imagine that the contestants were extremely cold.

"It's easy to go up the mountain but hard to go down, especially on this kind of steep terrain. The rocks are slippery, the vision is blurry, and the body starts to tremble uncontrollably, the kind that can't be stopped."

Uncontrollable shivering means hypothermia has set in. This stage is typically characterized by prolonged shivering while awake, but is also accompanied by increased blood pressure, heart rate, breathing rate, and the need to urinate. These reactions mean that the body is working hard to produce heat and resist heat loss.

"A close friend of mine, a girl, suffered from hypothermia when she was almost at the top of the mountain. She told me that she had hypothermia and sat down. Later, she was woken up by another female athlete. She then found that her leg was broken and bleeding, but she had no memory of how her leg was broken. This means that she lost consciousness during that time. I told her: You should thank the girl who woke you up, because you might have almost died today..."

The truly terrifying stage of hypothermia is when a person stops shivering. At this point, a person's mental state changes, and they may experience numbness and dullness of thought, slurred speech, visual impairment, irregular heartbeat, dilated pupils, drowsiness, and loss of fine motor skills. If you find someone around you in this situation, never leave him alone. In the article "Mountain Medicine: Hypothermia, a Disease That Can Easily Be "Saved" to Death", the author, who has extensive experience in outdoor adventures, mentioned that in outdoor sports, many people with moderate hypothermia (stage 2) hope that they can walk slowly behind them. They will say, "You go first, and I'll slowly catch up with you from behind." This sentence must not be taken seriously, and conditions must be created quickly to warm them up.

"The runners who retreated to the cabin later reported seeing several runners collapse along the way, lying motionless on the side of the road, foaming at the mouth (all the running groups have videos). One runner said that an elderly runner in his sixties "was dying," and asked the Blue Sky Rescue Team to rescue him as soon as possible."

At this point, the contestants I saw lying on the side of the road, unable to move and foaming at the mouth, had entered the very dangerous third and fourth stages and were no longer able to regulate their body temperature. In the third stage, the hypothermic person is unconscious and loses the sense of pain, and their heart rate, blood pressure, and respiratory rate further decrease. Some people may also experience symptoms such as atrial fibrillation and tachycardia.

20% to 50% of hypothermic people may experience hallucinations and take off their clothes. This is because the peripheral blood vessels begin to dilate after contracting to a critical point, and a large amount of warm blood flows from the core organs to the body surface, which accelerates the decrease in core temperature.

In the final stage, the person's muscles become rigid, and he or she may have an almost undetectable heartbeat or breathing; the heart may flutter and then stop beating.

The above are the typical symptoms of hypothermia. But we know that "cold" has other symptoms, such as chilblains, frostbite, trench foot, etc., which may appear together with hypothermia. Frostbite is also divided into four levels:

First-degree frostbite: superficial and reversible, but may be very painful when the extremities warm up;

Second degree frostbite: Blisters appear within hours or a day after frostbite, indicating deeper tissue damage;

Third degree frostbite: The entire layer of skin is damaged, turning black and hard.

Fourth degree frostbite: Frostbite of bones and tendons.

Frostbite is often caused by exposed skin or injured tissue and lack of movement, and symptoms may not appear for a long time, while hypothermia is caused by an imbalance in the body's heat gain and loss, and the process can be quite rapid.

So, how can you know whether you or your companions are suffering from hypothermia, too cold, or frostbite?

If you feel that your face is painful from the cold or your ears are about to fall off, it means it is too cold and you are at risk of frostbite.

If you are "shivering from the cold", you may be on the verge of hypothermia. When you stop shivering, the real danger comes. This is also where hypothermia is more difficult to detect and more dangerous. If your partner does not shiver at all when it is very cold and no longer responds to you, then it is very dangerous.

Remember, hypothermia is a potentially life-threatening medical emergency. If you experience hypothermia, seek medical assistance immediately.

References

[1] https://en.wikipedia.org/wiki/Hypothermia#cite_note-NEJM2012-2

[2] DO I HAVE HYPOTHERMIA, OR AM I JUST REALLY COLD?, https://healthcare.utah.edu/the-scope/shows.php?shows=0_3w7atmmx

[3] Hypothermia Can Happen Both Indoors and Outdoors, https://health.clevelandclinic.org/hypothermia-can-happen-indoors-surprising-facts/

[4] How to take protective measures in cold weather? http://www.chinacdc.cn/jkzt/hjws/ncgc_10782/201901/t20190103_198629.html

[5] Frostbite vs. Hypothermia Differences in Symptoms and Stages, https://www.emedicinehealth.com/frostbite_and_hypothermia_symptoms_and_stages/article_em.htm

[6] How Does a Person Freeze to Death?, https://www.livescience.com/6008-person-freeze-death.html

[7] Wild medicine: Hypothermia, a disease that can easily be “saved” from death