Heat strokes show the most fearsome face of episodes of high temperatures such as the one that has hit Spain in the last nine days. The speed and virulence with which these processes are triggered, which can cause the death of a healthy person in a few minutes, remind us of the dangers that heat poses to humans, even if they only account for a small part of the mortality related to the rise of the thermometers.
The skin is the battlefield where the body defends itself against heat. It is here that some 600 glands per square centimeter pump sweat out of the body to compensate for the rise in temperature. It is also towards the skin, in order to cool down, where the greatest blood flow is directed as a result of the dilation of the arteries ordered by the hypothalamus. “These are the two main compensatory mechanisms that are activated when we are hot, just as it happens when we do intense physical activity,” says Juan Torres Macho, head of the internal medicine service at the Infanta Leonor Hospital (Madrid).
This is the reason why combining both things, high temperatures and exercise, is not recommended. The risk is that the body’s efforts are insufficient to lower body temperature, which will begin to rise from 36.7 degrees and when it reaches 40.5 it already puts the person’s life at risk. It is the dreaded heat stroke, which has caused the death of 757 people in Spain between 2003 and 2018, according to data from the National Institute of Statistics.
“As of 40 degrees, some physiological processes in the body are altered and an inflammation mechanism begins that produces a cascade of enzymes that interferes with the normal functioning of vital organs. It is a process that, once it has started, is difficult to reverse”, explains Torres Macho.
1, Thermoreceptors in the skin give information to the hypothalamus about indoor and outdoor temperatures. When it detects an increase, it activates mechanisms to regulate body temperature and normalize its value.
2, The first defense mechanism is perspiration. It is produced by sweat glands in the skin. Sweat is made up of water, mineral salts and toxins. When it evaporates, excess heat is released.
3, Capillaries are small blood vessels that are close to the surface of the skin. As the capillaries dilate, a large amount of blood is closer to the air, which makes it easier for it to cool more quickly.
Headache, confusion, and lightheadedness are warning signs that a chain of events has begun that can lead to loss of consciousness, seizures, and heart failure. Although difficult to stop and with a high mortality, the recommendations to stop the process are to lay the affected person in a lateral position in a cool area, soak the skin with water and damp cloths to help lower the temperature and alert the emergency services.
The latest studies show that more than 1,300 people die each year in Spain from causes attributable to high temperatures. Of these, only a small part are due to heat stroke. In the worst summer since there are records, that of 2003, 182 people died for this reason, about 3% of the more than 6,600 deaths attributed to that episode of extreme temperatures.
“Heat strokes are the most extreme cases of the important impact that heat has on people’s health,” explains Juan Armengol, president in Madrid of the Spanish Society of Emergency Medicine (SEMES). “What we are seeing these days is a lot of dehydrated older people, more than in other years. They arrive dazed and disoriented. Older people, like younger children, regulate heat less well and don’t feel as thirsty, so it’s important to remind them to drink. You also have to check their medication, because they often take diuretics and anti-tension drugs that must be adjusted at this time, because they already lose much more fluid through sweat, “adds Armengol.
“Heat stroke and dehydration are two different processes, but the way to prevent them is the same. Drink, take shelter from the sun and high temperatures and do not do physical activity at the worst times of the day”, recalls Torres Macho. In addition to drinking, it is also important to maintain a balanced diet. “The high sweating also unbalances the levels of mineral salts. The increase in potassium levels is especially dangerous, because they alter the electrical mechanisms of cardiac cells, which can lead to the patient suffering arrhythmias and, in extreme cases, cardiac arrest”, adds this specialist.