A couple died while climbing the Ice Crystal Peak at night. Why is hypothermia the biggest "invisible killer" outdoors?

Recently, the news that a young couple died of hypothermia while climbing the Qinling Ice Crystal Peak at night has attracted public attention and once again sounded the alarm for outdoor enthusiasts. How terrible is it to suffer from hypothermia outdoors? If you suffer from hypothermia, should you wrap yourself up tightly or drink hot water to keep the cold away? Today we will systematically introduce effective ways to deal with hypothermia.

Image source: Xi'an Huyi District Emergency Management Bureau

01 Why is hypothermia fatal?

Hypothermia, also known as hypothermia, refers to a condition in which the body's core temperature drops below 35°C.

The core temperature of the human body remains basically constant . The core temperature here refers to the temperature of the heart, lungs, brain and other major organs that maintain life and the central nervous system. The reason why it can remain basically unchanged is that there is a body temperature regulation system in the human body. The temperature receptors such as the skin and mucous membranes transmit the temperature changes of the outside world to the body temperature regulation center, namely the hypothalamus, thereby regulating the body's heat dissipation and heat production process to maintain a normal body temperature level. The normal body temperature of the human body is generally 36℃~37℃.

When the body's heat loss is greater than its heat supply, the temperature of the body's core area drops, and this "dynamic balance" will be broken , leading to a series of symptoms such as chills, impaired consciousness, cardiopulmonary failure, and even death.

Hypothermia does not occur all at once, and generally has three main stages of development:

Mild hypothermia (body temperature 32℃～35℃) : The patient's body temperature drops at this time, and he or she has severe chills, cold limbs, pale face, slurred speech, memory loss, slow pulse, etc., "goose bumps" appear on the skin, and urination increases.

Moderate hypothermia (body temperature 28℃ ~ 32℃) : As the patient continues to lose heat, his muscle incoordination becomes more obvious, his movements become slower and more difficult, and he often has unsteady steps, confusion, pale face, blue lips, ears, fingers and toes, and some people experience abnormal undressing.

Severe hypothermia (body temperature below 28°C) : At this stage, the body temperature drops severely and the situation is the most critical. The patient loses consciousness and enters a state similar to "hibernation", which is manifested by muscle stiffness, slow pulse and breathing rate, a sharp drop in blood circulation on the surface of the body, and loss of consciousness. If emergency measures are not taken immediately, there is a risk of death from cardiopulmonary failure at any time.

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02 Extremely cold weather with ice and snow is not the only "accomplice" of hypothermia

Although hypothermia does not happen all at once, as long as you pay a little attention, you can find the "signal" of its arrival. Generally speaking, hypothermia must meet three conditions: the human body is exposed to an extremely low temperature environment for a long time, the heat production mechanism in the human body is suppressed, and the body temperature drops faster. Only when all three conditions are met at the same time will the human body be in danger of life. Among the three conditions, the first is the main reason, and the second and third are more of a self-conditioned reflex remedial mechanism of the human body.

The main factors affecting outdoor hypothermia are the temperature, air humidity and wind speed in the exercise area . If you encounter a sudden change in weather during outdoor activities, such as a sudden drop in temperature, increased humidity, and strong winds that make it difficult for people to stand, you must be vigilant. Most cases of death due to hypothermia are accompanied by severe meteorological conditions. For example, the hypothermia event at the top of the Qinling Ice Crystal occurred in areas with severe climatic conditions such as strong winds, rain, and dense fog. In May 2021, the mountain marathon held in Baiyin, Gansu Province encountered extreme weather, resulting in the death of 21 contestants and injuries to 8 people. On November 13, 2021, 4 geological survey team members died of hypothermia while working in the field in Ailao Mountain.

It must be pointed out that hypothermia has nothing to do with the season. Even in summer, hypothermia can occur . For example, sweating a lot during long-distance running in the summer will take away the body's heat. If you do not change clothes in time, or encounter heavy rain and strong winds, water will dissipate the body's temperature faster through heat conduction, causing rapid heat loss, thereby increasing the risk of hypothermia. Death from hypothermia after being drunk in winter is also one of the common causes of death from hypothermia, because drunkenness can cause the human body to misjudge changes in the external environmental temperature. At the same time, drinking alcohol is more likely to cause peripheral vasodilation, making it more difficult to retain heat in the body.

03 Improper rewarming methods may lead to additional dangers

As outdoor sports become more and more popular, people want to get close to nature, relax, and pursue "poetry and distance", but underestimating their own physical fitness and lacking clear judgment on the dangers and potential risks of the wild in the crossing area may lead to accidents. Taking this hypothermia incident as an example, Bingjingding is located in the Binghecui Scenic Area at the highest point of the Qinling Zhuque National Forest Park in Xi'an, with an altitude of about 3,015 meters. The climate is changeable and the terrain is complex. From mid-to-late November to early April of the following year, the snow on the top of the mountain does not melt, and the snow on the shady slope can be preserved until mid-to-late April. Before outdoor crossing or mountaineering, you must make an accurate assessment, bring good equipment, and arrange the itinerary reasonably, and don't take risks.

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In a cold environment, if a person has abnormal behavior and speech, he or she should be suspected of hypothermia. Hypothermic patients who can move are still in a mild state of hypothermia. They should immediately build a shelter, find a place to rest in the wind and rain, change wet clothes, add warm clothes and eat carbohydrates. At the same time, avoid strenuous exercise to prevent the return of cold blood in the limbs to further lower the core body temperature.

If the patient has lost the ability to move, it means that the patient has entered a state of moderate to severe hypothermia. First, move to a place that is sheltered from the wind and rain and isolated from the ground, change wet clothes and wrap the patient in an insulating layer. If conditions permit, use a cloth to wrap a hot water bottle to warm the patient's armpits, groin, neck and other parts, and immediately send the patient to the hospital for treatment.

In addition, ordinary people can also judge the degree of hypothermia by observing whether shivering (shivering) cannot be controlled voluntarily. If shivering (shivering) cannot be stopped by one's own willpower, it usually indicates that the individual is already in a state of moderate hypothermia.

Wearing more clothes does not prevent hypothermia . If the clothes are soaked or have poor breathability, it will affect the retention and dissipation of heat. Therefore, in addition to paying attention to the performance of clothing, you should also prepare spare clothes such as underwear, warm clothing, neck covers, breathable and rainproof jackets, raincoats, hats, etc., so that you can "take off when it's hot, add more when it's cold, and change when it's wet."

Avoid rewarming too quickly or too vigorously . For patients with moderate or severe hypothermia, blindly rubbing the palms and soles of the feet, pouring hot water, or wrapping them in the same sleeping bag with healthy people are all incorrect ways to rewarm. If the patient is moved or the limbs are rubbed drastically, it may cause cold blood to flow back to the heart and even cause ventricular fibrillation, rewarming shock and other serious consequences. Drinking hot water will drastically dilate blood vessels, leading to hypotension, which will further cause a drop in core body temperature.

Outdoor "life-saving" life-saving blankets are useful, but they cannot completely prevent hypothermia . Emergency thermal blankets are very necessary. In case of bad weather, they can protect yourself or others and extend the waiting time for rescue, but their effect is limited and can only last for a short time (usually no more than 15 minutes). Therefore, when using a life-saving blanket, you should find a safer shelter as soon as possible or take other warming measures. At the same time, it is necessary to pay attention to the life-saving blanket to fit yourself (skin), and be sure to wrap the head, keep all the fabrics close to the skin, and then put on clothes to avoid it from being damaged or ineffective.

Screenshot source: Henan Provincial Emergency Management Department official TikTok account

Prevention is always better than cure. When exploring outdoors, everyone should be fully protected from wind and cold. Choose the right clothes and equipment to ensure that you can cope with sudden weather changes. Every time we set out, the farthest point we reach or the highest peak we climb is not the end, but returning home safely is our ultimate goal.

author:

Researcher Zhang Ying, Director of the China Science Writers Association, Executive Vice Chairman and Secretary General of the Emergency Science Popularization Committee

Liu Hanbin, Senior Engineer, Shanxi Coal Geology Bureau, PhD in Geology

Produced by: Science Popularization China

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