Critical Hyperthermia: A REALLY STAT EMERGENCY!


Our collaborator, Dr.s Alain Vadeboncourt, MD, an emergency physician and professor at the University of Montreal, is a medical advisor to Team STAT. Here he draws on plot lines from the TV series to provide a more in-depth view of some of the diseases diagnosed on screen.

This Thursday on the show STAT, concluded that several patients in critical hyperthermia had access to the episode in a rather intense manner, since it was indeed an emergency. Melody, who has a brain tumor, has convulsions and another older patient is unconscious, while the rest of the group is also in poor shape.

Critical hyperthermia occurs when the body fails to regulate its internal temperature, which then reaches dangerously high levels, usually above 41°C. Fever is unrelated: of environmental origin, it constitutes a serious medical emergency, which can lead to a fatal spiral.

The elderly, who regulate their temperature less, are more likely to suffer from this type of hyperthermia, for example during heat waves. The same applies to children as well as to people who must stay active during periods of high heat, such as construction workers. On STAT, this situation arises in lieu of a questionable session of “therapeutic sweating” that went really badly.

Our cooling mechanisms

However, the body is usually well equipped to defend itself, so our body temperature remains stable between 36.5°C and 37°C, regardless of conditions, making us “warm-blooded” animals. The reason is simple: any deviation harms the functioning of the cellular processes and organs that ensure our survival.

Our body temperature is therefore regulated by a very delicate system, which uses various mechanisms to maintain the temperature at that optimum level for the functioning of the organism.

When the ambient temperature is higher, the body attempts to “lose heat” by transferring energy from calories to the environment. For example by heating, convection and evaporation, which I will explain later.

The deep brain plays an important role in regulating body temperature by using both ambient information and body temperature to fine-tune thermoregulatory mechanisms. But in order to do so effectively, the conditions must be right.

In the told story, the apparent environmental factors triggered hyperthermia, negating each of the mechanisms normally activated to cool the body.

complex adaptive response

One of the main factors in regulating the internal temperature isevaporation Water, whether in exhaled air or on the surface of the skin, in the form of perspiration. Since it takes energy to convert water from liquid to vapor, a lot of heat energy is released. Except that if evaporation is compromised, the mechanism can no longer be activated.

During this “therapeutic sweat”, the heads of the characters were placed in a box saturated with moisture, which prevented the lungs from promoting evaporation. Water cannot evaporate properly from the leather either because of the (waterproof) plastic covers.

This is also why high humidity makes it difficult to tolerate heat. Finally, if you are dehydrated, as in the show, it is difficult to produce enough sweat.

Another important mechanism, pregnancy, involves a uniform passage of “fresh” air over the skin, which ensures a continuous transmission of energy. This is why a fan or wind helps us a little during periods of heat. But since the characters were wrapped in a blanket during the sweat session, they couldn’t be transported with the load.

The body also loses heat radiation, Any hot object emits thermal radiation, especially in the infrared. It is on this principle that infrared cameras work to see living objects in the dark.

However, since the body also receives radiation from light and surrounding objects, it must emit more than it receives to use this mechanism effectively.

In the episode, the use of radiation and the maintien d’une température élevee dans la pièce empêchaient le corps des personnages de perdre de la chaleur, ce rayonnement étant compromis by the port of vêtements et l’ajout de couvertures, les isolant from the environment.

Diagram of a cross-section of human skin, the organ that regulates body temperature. When you need to lower the temperature, the arteries dilate, bringing more blood into the capillaries on the surface of the skin (the epidermis), which results in increased heat loss by radiation. Sweat glands secrete sweat that evaporates on the surface of the skin. Convection corresponds to the uniform passage of air over the epidermis. Conduction, which consists in the transfer of heat from the body, is not demonstrated: it can take the form of an ice cube placed on such skin. Author scheme.

The part of the deep brain that specializes in thermoregulation is called the hypothalamus. Since this manages several aspects of the functioning of the body, it applies its usual methods of increasing the rate of respiration, dilating the blood vessels of the skin, stimulating perspiration, and accelerating cardiac output and respiration. Other than that in the episode, he was overwhelmed by the situation.

The brain is also there to modify behavior in hyperthermia: exposing yourself to the cold, undressing, drinking water and going into the shade are thus effective adaptive mechanisms. Here, however, the teacher’s conditioning convinced the participants not to listen to their brains, which is another problem.

Diagram of a cross-section of the human brain. The hypothalamus (in blue) is the center of temperature regulation. By receiving its temperature information, it can direct its adaptive messages by the neural pathway, passing through the brain stem and spinal cord, as by the hormonal pathway, via the pituitary gland, the master gland of the human body. It can also send a message to the cortex (the upper part of the brain) to induce adaptive behavior. Author scheme.

Medical emergency

When the temperature gradually rises to critical levels, this type of hyperthermia is called “heatstroke”. It is a medical emergency that can cause brain damage, serious metabolic disorders, bleeding and blood clots as well as damage to many internal organs, such as the liver and kidneys, and even death in extreme cases or in the absence of treatment.

Symptoms of life-threatening hyperthermia include nausea, vomiting, dizziness, confusion, and even loss of consciousness.

The goal of treatment is to restore the natural mechanisms of temperature regulation by helping the body achieve this, often working to lower the temperature in critical situations. Using acetaminophen does not change anything and is even not recommended.

The first step is rather to remove people from this heated environment – which was done in the program after an outside intervention – and then undress so that their bodies can again radiate their heat and effective perspiration is restored.

To promote sweating, solutions must be installed in the emergency room to properly hydrate patients, and the body must have an adequate fluid reserve for perspiration. These solutes can also be cooled, up to 4°C, to help lower body temperature, which then transfers part of their heat to this fluid.

Take the heat out of the body

A simple and widely used method is to facilitate evaporation by installing fans that provide continuous circulation of air over bare skin. The natural mechanism is improved by regularly spraying water over the entire surface, which takes part of the body heat with it as it evaporates.

Another improved mechanism is conduction, whereby any body transfers energy to another through direct contact. Applying ice packs where large blood vessels pass (in the neck, armpits, and groin) allows for such a direct transfer of energy from the body to the ice that melts.

In extreme cases, outside or in equipped clinical settings, a hypothermic patient may be immersed in a bath of very cold water while being monitored. These baths help lower body temperature by promoting conductive heat loss.

Finally, if the patient begins to shiver, which results in heat, muscle relaxants can be injected.


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