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Cause for silent breathlessness deciphered – healing practice

Why does COVID-19 lack oxygen without shortness of breath

Some people suffer from COVID-19 from so-called silent breathlessness (silent hypoxemia), which is characterized by life-threatening and symptom-free oxygen deficiency. It is extremely puzzling that, despite the lack of oxygen, the human body’s alarm system should simply fail. A new study has now made it clear what causes silent breathlessness in COVID-19.

In their study, the researchers from Boston University and the University of Vermont jointly looked for the causes of silent respiratory distress in COVID-19. The results of the investigation were published in the English-language specialist journal “Nature Communications“Published.

What causes silent breathlessness?

So far, the causes of the silent hypoxemia in COVID-19 have been unclear. The latest results show that at least part of the problem is lung malfunction. With this malfunction, more blood is pumped into the broken instead of the intact lung areas. In addition, existing blood clots and insufficient blood flow disrupt the exchange of oxygen, the researchers report.

Oxygen deficiency without typical symptoms?

There are people suffering from COVID-19 who do not cough or noticeably Shortness of breath and who show no evidence of extensive lung damage, but still have a dangerous lack of oxygen. The existing oxygen saturation of the blood sometimes reaches such low values ​​that the affected people actually have to pass out.

Can COVID-19 disable a critical alarm system?

“We didn’t know that something like this was physiologically possible at all,” reports study author Professor Bela Suki from Boston University in one Press release. Normally, sensors in the carotid arteries alert the brain as soon as the actual balance of carbon dioxide and oxygen in the blood is no longer correct. Exactly this alarm system seems to be partially deactivated in the event of an illness with COVID-19. The reasons for this were unclear.

In addition to its other effects, the viral infection is believed to also affect the respiratory center in the brain. This area in the brain triggers the feeling of shortness of breath when there is a lack of oxygen, the experts explain.

SARS-CoV-2 can penetrate the brain

Other studies have already shown that SARS-CoV-2 can penetrate into the brain via the nose and the olfactory systemwhere that Coronavirus is also detectable in parts of the brain stem. The breathing center is also located in this area.

Why does silent breathlessness occur at an early stage?

The researchers were also interested in why silent breathlessness occurs particularly in the early stages of COVID-19. In this phase of the disease, the lungs usually appear to be only slightly attacked. “These patients have hypoxemia, although CT images of their lungs show only minimal areas with impaired ventilation,” explains Professor Suki. The research group used patient data and computer simulations to investigate what happens in the lungs in such a case.

Control of the lungs incorrect?

The experts assumed that the control of blood flow to the lungs may be faulty. Normally, a feedback mechanism ensures that the venous blood flows primarily to where the air exchange works well. When areas of Lunge are poorly ventilated due to inflammation or injury, the blood vessels in this area constrict. Through this so-called hypoxic vasoconstriction, the blood is primarily diverted into the still intact area and the blood is adequately supplied with oxygen, the researchers explain.

No hypoxic vasoconstriction in COVID-19?

Such a diversion does not seem to work properly for some people suffering from COVID-19. In affected persons, the blood vessels in damaged lung areas no longer contract. This prevents the blood flow from being diverted. “Failure to do this could lead to a significant disproportion between breathing and oxygen exchange in the lungs,” reports Professor Suki.

Lung damage was simulated in a lung model

The research group used a biophysical lung model to find out whether such a malfunction could explain the lack of oxygen in the affected person. In the model, the experts reduced the air supply in 17 percent of the lung tissue. These effects are comparable to the lung damage caused by COVID-19 in the early stages, the researchers explain. The team then simulated various blood flow and oxygen exchange scenarios during the investigation.

What causes reduced oxygen uptake?

It was found that if the veins in damaged lung areas remain open or even widen instead of contracting, this can lead to a significantly reduced oxygen uptake of the blood. However, the observed effect is insufficient to explain the abnormally low oxygen saturation in some people with COVID-19, the experts explain.

However, there is another factor that can trigger hypoxemia. It turned out that with COVID-19 disease, gas exchange is also impaired in the healthy areas of the lungs.

Causes of impaired gas exchange

Possible causes include, for example, blood clots and embolisms in the small pulmonary veins. “If such thrombotic embolisms occur in the early stages of COVID-19, they can increase the malnutrition in the lungs and hypoxemia,” explains the research group.

Mismatch between ventilation and perfusion

There is also an imbalance between the actually sufficient supply of oxygen in the still intact alveoli and the ability of the blood to absorb this breathing gas. In such a case, experts speak of a mismatch between ventilation and perfusion. Possible causes for this include, for example, inflammation of the vessel walls, but also insufficient blood flow and Blood pressure be in the pulmonary capillaries.

Coronavirus not only attacks lung cells directly

According to the research group, this suggests that an infection with the coronavirus not only directly attacks the lung cells, but also disrupts the regulation of lung function in several ways. This is the explanation for why oxygen deficiency occurs even in people whose lungs actually appear to be largely intact, the researchers sum up.

“People react very differently to this virus,” explains Professor Suki. For this reason, it is particularly important to find out all possible causes for the dangerous lack of oxygen that occurs. According to the experts, this could help identify the right treatment for COVID-19 patients. (as)

Author and source information

This text corresponds to the requirements of the medical literature, medical guidelines and current studies and has been checked by medical professionals.

Sources:

  • Jacob Herrmann, Vitor Mori, Jason H. T. Bates, Béla Suki: Modeling lung perfusion abnormalities to explain early COVID-19 hypoxemia, in Nature Communications (veröffentlicht 28.09.2020), Nature Communications
  • Boston University: Three Reasons Why COVID-19 Can Cause Silent Hypoxia (veröffentlicht 08.10.2020), Boston University



Important NOTE:
This article is for general guidance only and is not intended to be used for self-diagnosis or self-treatment. He can not substitute a visit at the doctor.

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