Heat wave: recognizing heatstroke and protecting yourself against it

A vague of heat arrives in France, with temperatures approaching 40°C. The elderly and children can be particularly vulnerable… but it is often forgotten that these heat-related illnesses can occur even in a young, healthy person who is well hydrated. It is enough that the heat is stronger than the body can withstand.

Heat stroke (hyperthermia) occurs when our body’s ability to dissipate heat is exceeded and it can no longer cool itself. This may be due to a strenuous exercise such as the high temperature of the environment, the fact of being in a hot atmosphere (car closed, etc.)

To counteract overheating, we increase our sweat production and the small blood vessels in our skin dilate to bring the heat to its surface in order to evacuate it. However, a hot and humid atmosphere reduces its effectiveness.

What happens in our body during prolonged exposure to excessively high temperatures?

Here are the stages of this “thermal discomfort” and what amplifies the risk of being the victim. Cramps are the first stage of this process, followed by exhaustion and finally the actual heat stroke.

Multiple levels of risk: mild, moderate, severe

the heatstroke can be serious and lead to brain damage, coma and death if not taken care of. It is characterized by a considerable increase in body temperature, which can then rise to more than 40°C.

People with hyperthermia gradually become confused, irritable or even aggressive, have headaches, dizziness and sometimes hallucinations. Their skin is reddened, they feel an intense thirst. They may have difficulty walking, muscle tremors, pulse more than 130 beats per minute, suffer from nausea and breathe faster than normal.

This constellation of symptoms may feel like taking cocaine or a reaction to a drug likeaspirininfection or alcohol withdrawal.

Any victim of heat stroke should have their body temperature lowered immediately.

To do this, she must be placed in the shade, undressed, and water, preferably hot, can be sprayed on her body with a fan directed at her. Hot water is used to avoid inducing chills, which is a mechanism used by the body to generate heat.

Cooling should be discontinued when body temperature returns to around 39°C to prevent the transition to a hypothermic state, i.e. when core body temperature becomes too low.

Almost everyone with heat stroke is admitted to hospital to monitor blood electrolytes (sodium, potassium…) and their level ofhydrationas well as to assess other risks of problems such as organ dysfunction.

Other heat injuries are not as severe. They can, for example, be limited to heat cramps: painful contractions of large muscle groups (legs, stomach, etc.) resulting from the inappropriate practice of an activity physical intense in the heat and insufficient hydration. Heat cramps do not affect our mental abilities or cause our temperature to rise too high.

The consumption ofalcoholfatigue and being sick before exercising increase the risk of suffering from cramps and other heat-related side effects.

There is no specific treatment other than rest, get into a cool environment, and return to adequate hydration. If the dehydration was important, the use of a infusion intravenous may be considered.

Heat exhaustion is a mild condition involving dehydration and minor hyperthermia: the body temperature rises, but then usually remains below 40°C. Those affected may have nausea, vomiting, dizziness, signs of dehydration – and fatigue, therefore. Brain functions are not affected.

Treatment is the same as for cramps and prognosis is excellent, because the main organs are very little affected. It may be preferable to be examined by a doctor, without this necessarily leading to hospitalization.

Our cooling system

Our body works best with a internal temperature of 37°C. To maintain a constant temperature, it uses various homeostatic mechanisms. In case of cold, the shivers thus serve to generate heat.

In case of heat, our body must dissipate it to stay in its optimal operating zone. To cool itself, it uses respiration, conduction, convection, perspiration and evaporation and radiation. Depending on the temperature, the area of ​​the body, whether we exercise or not, the rate of heat evacuated varies a lot.

Conduction involves direct physical contact with cooler objects. An example would be taking a glass of ice water in your hands. But this mechanism is only valid, on average, for 2 to 3% of the heat we lose.

Convection, which accounts for about 10-20% of heat loss, involves the transfer of heat to theair or the water around us. Especially when we use a fan to blow in fresh air, take a cold shower, etc.

About 30% of our heat loss comes from evaporation. We do this through perspiration, but other animals have different mechanisms: dogs panting, the kangaroos lick their forearms, etc.

Radiation is our most important means of losing heat. It transfers the heat from our body in the form ofelectromagnetic waves and can account for about 40% of the heat loss. Unfortunately, as soon as the ambient temperature exceeds 35°C, the radiation loses its effectiveness.

All these mechanisms regulators can be influenced by other factors including humidity, our clothing, hydration, etc.

Prevent heatstroke

Research has been done on the factors genetic that predispose some people to be more vulnerable to heat. Certain medications appear to help prevent these effects in animal testing. But the key to combating the rise in temperature and its consequences is the prevention.

Minimize strenuous activities in hot weather, adapt your environment by staying in air-conditioned or well-ventilated buildings, reduce blinds and shutters, use fans, stay hydrated, and limit your alcohol and medications.

Infants, the elderly, and people with chronic illnesses may not be able to modulate their heat exposure as well as others, and should take special precautions.

Athletes must also be aware of the risks they run to practice under these conditions.

Therefore, on hot days, grab a bottle of ice water, head to a cool indoor environment, and go for a quiet activity if you want to avoid falling victim to the heat.