Shenyang recently entered the “summer” season, there will be a continuous hot and muggy “sauna” weather. Today’s weather forecast suggests that the maximum temperature may be as high as 38°C, while the humidity exceeds 60%. In this hot and humid weather, many middle-aged and elderly people, who are relatively weak, are prone to “heat stroke”, which is hazardous to health and even to life. Why do people get heatstroke? The normal human body has a well-established thermoregulatory mechanism. Depending on the external temperature, the hypothalamus thermoregulatory center maintains the relative stability of body temperature by producing and dissipating heat. When the external temperature rises, people can dissipate heat in four ways: radiation, convection, evaporation and conduction. When the room temperature is 15-25℃, radiation is the most important way to dissipate heat, and as the temperature increases, people will produce heat and sweat, and the evaporation of sweat becomes an important way to dissipate heat. Convection and conduction are two ways to dissipate heat to a lesser extent. When the peripheral temperature is higher than the body temperature, this mode of heat dissipation by radiation cannot function. At the same time, the humidity in the air is very high, and the evaporation rate of sweat is slow after elimination, and these are the factors that affect the decrease of body temperature. So in a hot and humid environment, people are more likely to suffer from heat stroke. Once heat stroke occurs, a person’s body temperature will rise to a maximum of 42°C or more, which will have a direct damaging effect on cells and cause multi-organ system failure. For example, it causes cerebral edema leading to coma, myocardial ischemia, cardiac arrhythmia occurs, serious electrolyte disorders, acute renal failure, etc., so it must be taken seriously. Heat stroke has three forms of manifestation, one is heat cramps, that is, after a lot of sweating and drinking water, headache, dizziness and spasms of the limbs and abdominal muscles, generally without a clear increase in body temperature, which is the early manifestation of heat stroke. Another form is heat exhaustion, which is mostly seen in the elderly and patients with chronic diseases. It manifests as excessive sweating, fatigue, dizziness, headache, hypotension and even syncope, when the body temperature usually does not exceed 40°C. The most severe form is pyrexia, which presents with hyperthermia (body temperature over 40°C) accompanied by delirium. Early organ damage is to the brain, liver, kidneys, and heart, respectively. In young and middle-aged people, strenuous physical work in hot and humid environments can lead to exertional pyrexia, acute rhabdomyolysis, acute renal failure, etc., with a high mortality rate. In contrast, non-exertional pyrexia occurs in elderly and frail people living in crowded and poorly ventilated cities. Patients have no or little sweating, a large increase in body temperature, the initial onset is abnormal behavior, severe cases coma, and hypotension, shock, pulmonary edema, cerebral edema, and death about 24 hours after onset. Heat stroke treatment measures are basically the same, generally as soon as possible out of the hot and humid environment, stop work or exercise, and then quickly lower the body temperature, can be by taking off clothes, no deflated can be placed in cold water, or use a towel wrapped in ice to cool down. Those who are deflated can wipe their skin and use electric fans and air conditioners to cool down. Those who are ineffective can use ice saline gavage or enema. If complications occur, treat them for the complications. Heat stroke has a mortality rate of more than 50%, and the prognosis is particularly poor if left untreated. Heat stroke has much more serious consequences than we think! We advise middle-aged and elderly frail people to try to wear light-colored loose and breathable clothes when it is hot, and to wear a sun hat in the sun. Reduce outdoor activities in hot weather, improve the living environment, pay attention to ventilation, and apply electric fans and air conditioners to assist in cooling down. Drink water appropriately, in small amounts and many times, you can drink light salt water, avoid drinking large amounts of plain water at once, which can cause hypotonic cerebral edema.