Winter "hot" topic: prevention and first aid knowledge of heat stroke

Author: Liu Shuang, attending physician at Peking Union Medical College Hospital

Reviewer: Zhu Huadong, Chief Physician, Peking Union Medical College Hospital

In hot weather or environment, our body is like a running machine that needs to constantly dissipate heat to keep running normally. However, when the outside temperature is too high and exceeds our body's heat dissipation capacity, heat stroke may come quietly. Although heat stroke is not as common in winter as in summer, people may still suffer from heat stroke under certain circumstances, such as long-term physical labor or strenuous exercise in a high temperature, high humidity, and unventilated environment. Therefore, it is crucial to understand the relevant knowledge of heat stroke and master scientific prevention and treatment methods to protect our health.

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1. Why do people get heatstroke?

Before talking about this, we must first understand the mechanism of temperature regulation. Human body temperature is regulated by nerve cells in specific locations in the brain. They can keep our core temperature, that is, the temperature of important organs deep inside the body, at a stable state. The core body temperature of a normal person is about 37°C. It is usually measured through the rectum, which is different from the axillary temperature and forehead temperature we usually use. Compared with cold tolerance, people's tolerance to heat is actually worse. We can only tolerate a body temperature about 4.5°C higher than the normal range. The human body has a variety of heat dissipation mechanisms, such as heat conduction, convection and radiation. However, when the ambient temperature is too high, higher than the core temperature of the body, heat conduction, convection and radiation are ineffective. At this time, evaporation is the main heat dissipation mechanism of the human body in a high temperature environment. Our body uses blood to transfer the heat from the core of the body to the skin, evaporates sweat from the skin, and releases heat to the environment. But there are two prerequisites for this process to occur. The first is that we have enough blood volume to transfer heat, and the second is that there is a water vapor pressure difference between our body and the outside world. If our body does not have enough water, and therefore does not have enough blood volume to carry heat from the organs to the skin; or in a high humidity environment (relative humidity > 75%), there is not enough water vapor pressure difference, and heat cannot be dissipated through evaporation, thus causing heat stroke.

2. Can people die from heat?

People can die from heatstroke. As our body temperature rises, the body's oxygen consumption and metabolic rate will increase simultaneously, followed by a systemic inflammatory response, and the body's organs (such as the gastrointestinal tract, liver, and nervous system) will suffer from ischemia. In severe cases, such as when the body temperature exceeds 42°C, multiple organ failure will occur, and if not promptly intervened, it will lead to death.

3. What is the difference between heat stroke and heat stroke? If you have heat stroke, does that mean you won't get heat stroke?

We can understand heatstroke as a general term, and according to different pathophysiological mechanisms and symptoms, we currently divide heatstroke into heat cramps, heat syncope, heat exhaustion and heat stroke. Among them, heat stroke is the most serious type. It is defined as an increase in the body's core temperature (usually over 40.5°C) accompanied by central nervous system dysfunction when the environment is too hot and we cannot dissipate heat. Since heat stroke can be fatal, it needs to be identified and treated quickly. But no matter what the concept is, these are all manifestations of damage to our body caused by heat, and then damage to specific organs. They are not mutually exclusive and can occur alone, in combination, or gradually progress.

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4. What kind of people are at high risk of heat stroke and are relatively prone to heat stroke?

Children, the elderly, pregnant women, and obese people are at high risk of heat stroke. Exposure to high temperature and high humidity without adequate water intake to replenish fluid loss caused by sweating leads to dehydration, which is an important factor in heat stroke.

5. What are the symptoms of heat stroke?

In a hot environment, if someone is dizzy, thirsty, weak in the limbs, nauseous, and inattentive, and if he has a flushed or pale face, and a rapid breathing rate and heartbeat, it means that he is likely to have heat stroke. At this time, measures should be taken. If you delay, the patient is likely to have slurred speech, slow reaction, or even coma. However, there are two points to note. First, heat stroke is different from fever. The patient's skin does not necessarily feel hot to the touch. Some people do not feel hot to the touch, and may even feel clammy and cold. Do not ignore the possibility of heat stroke just because they do not feel hot to the touch. Second, children and the elderly may have atypical early symptoms, which need to be paid proper attention.

6. How to prevent heat stroke?

When the weather is hot or humid, you can take the following measures to prevent heat stroke: First, try not to overexert yourself and take breaks when exercising; second, drink enough fluids, such as water or sports drinks, so that you don't feel thirsty. Don't force yourself to drink a lot of fluids in a short period of time, and don't drink too much water every day; third, if you have the habit of exercising, you should exercise in the morning or evening when the temperature is lower. If you have to go out, wear loose and light clothing and don't wear too many layers. Finally, in addition to being outdoors, try not to stay indoors or in a car in a hot environment.

7. What is the most effective way to deal with heatstroke?

There are several ways, such as spraying cool water on your body and then sitting in front of a fan; going to a cool place, or going to an air-conditioned room or car to rest. You can drink water or sports drinks, but don't drink alcohol or caffeinated beverages. For example, take a cold shower, place ice packs or cool towels on the neck, armpits and groin. But be aware that some folk remedies are not feasible, such as using a large amount of alcohol to wipe the bath, or pinching the Ren Zhong point to cool down. These methods are unscientific and will worsen the condition if not handled properly.

8. How to provide first aid for heat stroke?

The patient should be immediately removed from the high temperature and high humidity environment, and rehydrated and cooled down. While cooling down, call 120 emergency number or send to the hospital for emergency treatment. If the patient is unconscious, be careful not to feed water or medicine to avoid aspiration. It should be noted that heatstroke does not require the use of antipyretic drugs to reduce the temperature. Our commonly used antipyretics such as acetaminophen or aspirin have no effect in the treatment of heat stroke, but may aggravate liver damage.