Hot, hot, hot, damn hot

Recently, the media reported that extreme weather has occurred frequently in many countries around the world, and abnormally high temperatures have continued, leading to a sharp increase in the number of deaths due to heat. China has entered the dog days of summer, and the heat is at its peak. It is also the hottest time of the year, and there are news reports of deaths due to heat from time to time. This phenomenon is further exacerbated by climate warming and increased carbon emissions.

With the changes in people's lifestyles and the ecological environment, global carbon emissions remain high. The factors that affect the earth's "heating" are numerous and very complex. The phenomenon of climate warming is difficult to reverse in the short term, and more and more people are dying from diseases caused by abnormal meteorological conditions.

Hot, hot, hot, it's so hot. This sentence is not a stuttering. It's so hot that there is a period after it, which means it's really hot. It's not an exclamation mark after it, which expresses the feeling of being really hot.

What people usually call illness caused by heat is called heatstroke.

How can heatstroke kill people?

In fact, heat stroke is a general term for heat stroke, heat exhaustion, heat cramps, and sunstroke, which are caused by dysfunction of the body temperature regulation center, sweat gland failure, and excessive loss of water and electrolytes caused by high temperature. They often exist at the same time and cannot be clearly distinguished.

Heat stroke often occurs under meteorological conditions of high temperature, strong heat radiation and high humidity. At this time, it is difficult for the human body to dissipate heat, causing heat accumulation in the body and rising body temperature. Heat accumulation in the body leads to dysfunction of the temperature regulation center, reduced cardiac output, and sweat gland failure, which further causes more heat accumulation in the body.

The characteristic manifestation is a triad of symptoms: high fever, no sweating, and impaired consciousness or coma.

Overheating and central nervous system symptoms, with an acute onset, often preceded by limb pain, headache, dizziness, nausea, vomiting, and subsequent high fever, with the body temperature reaching over 40 degrees Celsius. After profuse sweating, "stop sweating", dry and hot skin, rapid and weak pulse, and shallow breathing may occur. In severe cases, coma, epileptic convulsions, and pupil constriction may occur. If effective rescue measures are not taken in time, death may occur due to circulatory and respiratory failure, pulmonary edema, cerebral edema, liver and kidney failure, and disseminated intravascular coagulation. The mortality rate can reach 30%, and in high-risk special populations, it is as high as about 80%.

Heat exhaustion often occurs under meteorological conditions of high temperature and strong thermal radiation, and the pathogenesis is still unclear.

Before the onset of the disease, there are often headaches, dizziness, nausea, followed by thirst, chest tightness, pale complexion, cold sweats, weak or slow pulses, excessive sweating and cardiovascular dysfunction, causing hypovolemia and hyponatremia.

The characteristic manifestation is a diad: collapse, often without high fever.

The onset is rapid, with symptoms such as dizziness, headache, palpitations, nausea, vomiting, pale complexion, sweating, cold and clammy skin, low or slightly high body temperature, weak pulse, low blood pressure, syncope, convulsions of the hands and feet, and in severe cases, circulatory failure.

Heat cramps often occur in dry and hot environments with high temperatures and strong heat radiation. Due to excessive sweating, excessive loss of sodium chloride and potassium, imbalance of water and salt, and electrolyte imbalance, spontaneous impulses of nerves and muscles are generated, resulting in cramps.

The characteristic manifestation is a diad: severe muscle cramps and pain.

The spasm starts from the gastrocnemius muscle of the calf and spreads to the upper limbs and abdominal muscles. The spasm is often paroxysmal and rigid and symmetrical. The body temperature is normal and the patient is conscious. Before the onset of the disease, the patient sweats a lot, becomes thirsty, and has little urine. Proteinuria, muscle soreness, and weakness in the limbs may occur, followed by muscle spasms.

Sunstroke often occurs in open air and heat radiation environments in summer and autumn. Solar radiation or strong heat radiation directly acts on the unprotected head, causing heating of intracranial tissues and congestion and edema of brain tissues.

The characteristic symptoms are hexagram: severe headache and dizziness, blurred vision and tinnitus, nausea and vomiting, excitement or loss of consciousness, slightly increased body temperature, and facial flushing.

Effects of high temperature on human body systems

Effects on body temperature regulation. Blood circulation and sweat gland function play a major role in body temperature regulation. The body temperature regulation center and nervous system participate in and regulate all aspects that affect body temperature, so that heat production and heat dissipation are balanced. When regulation is out of control, heat stroke occurs.

Effects on water and salt metabolism. Increased sweating, the amount of sweating depends on the temperature, humidity, heat radiation and activity intensity.

Sweat is 99% water and less than 1% solid. Most of the solids are sodium chloride and a small amount of potassium chloride and urea, as well as vitamins B1 and C. Sweat is not a simple plasma filtrate, but a liquid secreted by sweat gland cells. When sweat flows through the lumen of the sweat glands, sodium and chloride are reabsorbed, so the sweat discharged at last is hypotonic. The water lost by sweating greatly exceeds the salt lost, thus leading to hypertonic dehydration, increasing plasma osmotic pressure and reducing urine volume. If water is not replenished in time, it will cause severe dehydration and water-salt imbalance in the human body.

Impact on the circulatory system. Excessive sweating leads to loss of water, which causes the blood to become concentrated. At the same time, in order to meet the needs of the activity, the blood supply to the muscles increases, which increases the heart activity, heart rate, stroke volume and minute output, causing an increased cardiovascular burden and even a pathological state in severe cases.

Impact on the digestive system: It significantly inhibits saliva secretion, reduces gastric acidity, weakens gastric motility, slows down small intestinal movement, reduces digestive tract absorption rate, and causes indigestion and an increase in gastrointestinal diseases.

Impact on the urinary system. Most of the water in the human body is excreted through the sweat glands. At the same time, the pituitary gland is affected by high temperature and strengthens the secretion of antidiuretic hormone, which greatly concentrates the urine. Protein, red blood cells, and casts appear in the urine, and renal insufficiency may occur.

Impact on the nervous system: The excitability of the temperature regulation center in the cerebral cortex increases, and the motor area of ​​the central nervous system is inhibited due to negative induction, so the muscle working ability, movement accuracy, coordination, reaction speed and attention are reduced, and the excitability of the central nervous system decreases.

Knowing how high temperature affects the human body, you will also know how to deal with it

Meteorological conditions in the working and living environment mainly include air temperature, humidity, airflow, thermal radiation and air pressure. These factors act on the human body in a comprehensive manner, affecting body temperature regulation and can cause disease under abnormal meteorological conditions.

The air temperature is affected by the heat source, the humidity comes from the evaporation of water and the release of vapor, and the airflow is affected by the external wind pressure and heat pressure.

Thermal radiation is the energy emitted by an object in the form of electromagnetic radiation due to its own temperature. When the surface temperature of the surrounding objects exceeds the surface temperature of the human body, a certain amount of thermal radiation is emitted to the human body, causing the human body to be heated; conversely, when the temperature of the surrounding objects is lower than the surface temperature of the human body, the human skin radiates heat to the surrounding objects.

The primary radiation from various heat sources, the secondary radiation from surrounding objects, and the conduction and convection heat raise the temperature of the working and living environment, creating a high temperature and strong heat radiation environment. The evaporation of water and the release of steam are accelerated due to the increase in temperature and airflow, forming a high humidity environment.

High temperature environment is divided into dry heat type and humid heat type. Dry heat type refers to high temperature and strong heat radiation. It is very difficult to dissipate heat through radiation and conduction convection, and it mainly relies on evaporation to dissipate heat. Humid heat type refers to high temperature and high humidity. Not only is it very difficult to dissipate heat through radiation and conduction convection, but it is also difficult to dissipate heat through evaporation. At this time, a large number of drops of sweat can be seen dripping down, but it cannot play the role of evaporation to dissipate heat. The water in the deep tissues or body fluids of the human body directly seeps out through the interstitial space of the skin and evaporates, which has nothing to do with the sweat secreted by the sweat glands.

The body's heat production and heat dissipation must always be in a dynamic balance, that is, thermal balance, in order to maintain normal physiological activities.

The body produces heat mainly through the metabolism of substances in the body, which provides energy for basic metabolism, food digestion, absorption and various activities. The intensity of activities is the main factor that increases heat production. The body dissipates heat mainly through radiation, conduction convection on the skin surface and evaporation from the skin and respiratory tract.

The thermal balance of the human body is a complex process of unifying the internal and external environment under the regulation of the central nervous system. The skin temperature receptors sense the changes in the temperature of the internal and external environment, and through the activities of the temperature regulation center (the heat production center in the posterior hypothalamus and the heat dissipation center in the anterior hypothalamus), the skin vasoconstriction, skeletal muscle activities, and the activities of effector organs such as sweat glands are changed accordingly. At the same time, the activity level of certain endocrine glands in the body is also changed, thereby regulating the heat dissipation and heat production capacity of the human body, keeping the body temperature at a relatively constant level, and achieving the thermal balance of the human body.

However, body temperature regulation is limited. If the body's thermal balance is disturbed, it is easy to cause heat stroke. Increased body temperature is the main sign of impaired body temperature regulation. The range of change of skin temperature with meteorological conditions is much greater than that of body temperature.

How to prevent and treat diseases caused by heat stroke

In case of signs of heatstroke or mild heatstroke, patients should immediately leave the high temperature environment, rest in a ventilated and cool place, and drink cool salty drinks orally.

In case of severe heat stroke, emergency rescue is necessary, mainly to correct the water and electrolyte balance and prevent shock and cerebral edema. Vitamin B1, C and calcium should be appropriately supplemented. For patients with high fever and coma, the body temperature should be quickly lowered to below 38 degrees Celsius.

Physical cooling and drug cooling are carried out simultaneously. During the cooling process, care must be strengthened and close attention must be paid to body temperature, blood pressure and heart condition. When the rectal temperature drops to around 38.5 degrees Celsius, cooling should be stopped immediately to avoid the risk of hypothermia and collapse.

Correct electrolyte balance. Do not replenish fluid too much or too quickly to avoid heart failure and pulmonary edema.

Sedatives should be used with caution in severe febrile cramps to prevent paralysis of the respiratory center.

Prevent shock.

Heatstroke prevention and cooling measures. Insulation is an important measure to prevent heat radiation. Ventilation is an important measure to eliminate convective heat and is also a way to create good meteorological conditions, including natural ventilation and machine ventilation. Reasonably adjust the work and rest time according to specific conditions, appropriately adjust the summer activity and rest system, shorten the duration of activities as much as possible, increase the number of breaks between work, appropriately extend the lunch break, and ensure adequate sleep.

Health care measures. Tea and salty drinks. Diet should supplement the protein, vitamins, water, inorganic salts lost due to excessive sweating and part of the heat energy affected by high temperature on basal metabolic heat. In summer, you should change clean and dry clothes frequently, wear light, thin, sparse, loose, soft, light-colored short-sleeved shirts, short skirts, and shorts with good breathability, heat absorption, moisture absorption, and moisture dissipation. The materials used should be rayon, silk, linen, and cotton knitwear.

The better the "four properties" of summer clothing, namely, air permeability, heat absorption, moisture absorption, and moisture dissipation, the more effective it is in absorbing sweat in a timely manner and evaporating it, while helping the human body to ventilate and dissipate heat, making people comfortable and cool to wear, and reducing the possibility of sudden increases in blood pressure. Silk clothes are cool and comfortable, beautiful and comfortable; cotton clothes are sweat-absorbent, breathable, and easy to wash.

The elderly, the weak and sick, fatigue, obesity, drinking, hunger, dehydration, salt loss, wearing unventilated or tight clothes, as well as those with fever, ulcer disease, organic diseases of the cardiovascular system, emphysema, active tuberculosis, severe anemia, liver, kidney, endocrine diseases such as diabetes, hyperthyroidism, congenital hypohidrosis, taking drugs that affect sweat gland secretion, organic diseases of the central nervous system, etc. may be at high risk of heatstroke in the hot summer and need special attention.