Medical warnings about the effects of high temperatures on the heart and blood vessels

Increased scientific interest in the complications leading to the death of the elderly

Advice: Dr. Hassan Mohamed Sandakji

Researchers from the Department of Cardiovascular Medicine at the University of Pennsylvania in Philadelphia presented their scientific review of the association of extreme temperatures with mortality of all causes in the United States.

According to what was published in the current May 19 issue of the journal JAMA Network Open, the researchers reported that by reviewing the monthly mortality rates of all causes, over a period of 10 years and at the provincial level (3,108 provinces). states in the United States, every extra hot day in the month is associated with additional deaths in adults, especially older men.

“heat” stress

The researchers summarized: “This cross-sectional study included a longitudinal analysis of the relationship between the number of days of extreme heat in the summer months over a period of ten years and mortality rates of all causes at the provincial level in those over twenty. years old. “

The World Health Organization (WHO) states: “Heat waves, particularly in large cities, will lead to more deaths, particularly among the elderly, exacerbating the leading causes of death worldwide, including cardiovascular disease, heart disease and respiratory system, diabetes and kidney disease. Long periods of high temperatures during the day and night place a cumulative physiological stress on the human body, exacerbating the leading causes of death worldwide.

And she adds in her report entitled “Heat and Health”: “The negative health effects of heat are predictable, and to a large extent preventable, through specific actions around dealing with extreme temperatures. “There is still insufficient awareness of the health risks posed by heat waves and prolonged exposure to high temperatures.”

In fact, the “health stress” of high air temperatures is not limited to the direct and immediate effects of heat on the body, such as sunburn, but rather the repercussions of its effects, which reduce the possibilities of relapse of stability in cases of chronic diseases. , which suffers from Including the elderly and middle-aged in particular. These include heart disease, high blood pressure, kidney weakness, liver failure and others. It is these effects that increase the incidence of health disorders associated with heat waves or periods of high temperatures expected in summer.

thermal effects

And on to the question: How does heat affect health? The World Health Organization answers this by summarizing the effects of heat on health in three aspects. One side is related to the direct effects, another is related to the exacerbation of chronic diseases, and the third is related to the important and indirect health effects.

In the first aspect, she says: “The heat absorption in the human body is due to a combination of external heat from the surrounding environment, and internal body heat due to metabolic processes. A rapid rise in heat gain, due to exposure to hotter-than-average conditions, impairs the body’s ability to regulate its internal temperature. It can lead to a range of diseases, including heat cramps, heat exhaustion, heat stroke and hyperthermia. ”

On the other hand, she says: “There can be deaths due to the heat and being admitted to hospital. It can occur very quickly (same day), or have an effect later (a few days) after the onset of heat waves. Even slight differences in average seasonal temperatures are associated with increased disease and mortality. Extreme temperatures can aggravate chronic conditions, including cardiovascular, respiratory, cerebrovascular, and diabetes-related conditions.

On the other hand, she says: “Heat also has important indirect health effects. Temperature conditions, and other factors such as humidity, wind and local levels of human acclimatization, can alter human behavior (depending on psychological condition), transmission of (infectious) diseases, health service delivery, air quality and critical social infrastructure such as e.g. energy, transport and water.

Heat and heart health

In its report entitled “Exposure to heat and cardiovascular health: a summary of the health departments”, the US Centers for Disease Control and Prevention (CDC) states: “The negative impact of extreme heat on cardiovascular health (CVD) has been observed across different geographical locations, and caused a significant increase in emergency department visits and hospitalization in elderly cardiovascular patients (over 65 years) on the fifth and sixth day after a very hot day.In one study of CVD hospitalization rates in New York City during June, July and August over a period of 13 years, a 3.6 (three-point-six) percentage increase in hospital admissions for 3-day delayed CVD, with each 1 ° C above the temperature-health effect curve, which for New York City ranges from 29 ° to 36 °. “A systematic review of 26 clinical studies found strong evidence that exposure to extreme heat directly increases cardiovascular mortality,” she added.

She also raised another aspect, namely the use of cardiovascular drugs and exposure to heat. “In the context of cardiovascular disease, it is important to note how medications prescribed for cardiovascular disease can exacerbate the harmful effects of extreme heat on the human body,” she said. Further studies are needed to better understand this relationship, and to inform how healthcare practitioners should proceed when advising their patients on this medication. ”

Mechanisms of onset of health damage from hyperthermia in heart patients

Mechanisms of health damage due to hyperthermia in heart patients, explained by the US Centers for Disease Control and Prevention, in summary: “Days that are warmer than the average seasonal temperature, or those with a somewhat high ambient temperature, with “High humidity, can cause increased levels of illness and death. This is done by compromising the human body’s ability to regulate its internal temperature, which is controlled by the autonomic nervous system and the cardiovascular system.”

“When it’s in a hot environment, the autonomic nervous system causes blood vessels in the skin to dilate so that more heat can be transferred from the body to the outside,” she explains. A portion of the blood from the abdominal organs and, in severe cases, all the body’s organs is also diverted to the skin to expel the internal heat. It requires maintaining a constant blood pressure during this large dilation of the blood vessels in the skin, and the redistribution and distribution of blood in parts of the body. It also requires an increase in the heart’s pump of blood, which is obtained by a high heart rate and an efficient contraction of the heart muscle. But in the elderly and those suffering from pre-existing cardiovascular diseases (especially coronary heart disease and weak heart muscle), the heart is not capable of meeting these new and increasing requirements to get rid of the body of excess heat, and then the repercussions and complications occur. ”

And he warns that “although high-temperature deaths and illnesses can be prevented, people still die from them every year.”

In fact, the rise in temperature is not the only factor associated with the damage of heat waves, but there are four other additional factors; These are: high humidity, physical exertion outside the home, the presence of chronic diseases in the person, and advanced or young age. When these five factors occur, the person’s chances of developing the negative health effects of high climate temperature increase.

This is important to explain. This is because the human body is negatively affected by high temperature when the body can not perform the process of self-cooling and expels the heat it has entered from the surrounding environment. In order for the cooling process to take place efficiently, three components are needed:

The autonomic nervous system works efficiently.

A cardiovascular device that effectively adapts to the cooling requirements of the body.

Availability of sweat glands that work effectively on the skin to secrete sweat, which is a problem in the elderly, and in those who take a type of heart and high pressure medication that affects the sweat glands’ secretory abilities of sweat fluid.

The U.S. Centers for Disease Control and Prevention sums up the issue by saying: “The key elements that negatively affect the body’s ability to cool itself in hot weather are:

High humidity in the air. It inhibits the evaporation of the sweat fluid and thus retains heat in the body.

Individual factors: such as advanced age or young age, obesity, fever in the body, heart disease, psychological diseases, poor functioning of the circulatory system, exposure to sunburn, taking certain types of medication and drinking alcohol are all factors that reduce work abilities The body’s own cooling system.

She said that in humid areas, and among people who have factors that increase their chances of being affected by high temperatures, drinking adequate amounts of water is an essential step, and making sure the air conditioner is available and in any cold places is another important step, and reducing the outdoors is a third step. An important fourth step is to reduce physical activity as much as possible in those hot climates. “Everyone should take these steps to prevent heat-related illnesses,” she added.

Healthy steps to deal with high temperatures

Under the heading “What measures should the general public take in the face of rising temperatures?”, The World Health Organization summarizes the following steps:

Keep your home cool, especially the bedrooms. Ideally, the room temperature should stay below 32 ° C during the day and 24 ° C during the night.

Use the night and early morning air to ventilate and cool your home, when the outside temperature is low.

To reduce heat charge inside an apartment or house, close windows that face the sun during the day, and turn off artificial lighting and as many electrical appliances as possible.

– If your accommodation has air conditioning, close doors and windows and keep electricity you do not need to keep you cool, to ensure that power remains available and to reduce the chance of community outages.

Electric fans may offer comfort, but when the temperature exceeds 35 ° C, they may not prevent heat-related illnesses.

It is important to drink fluids.

Avoid going out at the hottest time of the day.

Avoid strenuous physical activity if you can. If you have to do it, do it during the coldest part of the day.

– Stay in the shade.

Do not leave children or animals in parked cars.

Keep the body cool and hydrated.

– Take a cold shower.

Wear light, loose-fitting clothing made from natural materials.

When you go out, wear a wide-brimmed hat and sunglasses.

Use bedding and light sheets to prevent heat buildup.

Avoid eating large meals and eat small meals more than once a day. Avoid foods that are high in protein.

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