The main cause of death with COVID-19: what is acute respiratory distress syndrome and who does it threaten
'11.05.2020'
Source: Medusa
In many cases, a new coronavirus infection does not cause symptoms or causes only minor ones. When the disease is more serious, a person develops pneumonia, that is, pneumonia. This can lead to a condition called acute respiratory distress syndrome (ARDS), writes "Jellyfish".
In short, with ARDS, the lungs are damaged due to inflammation, they contain less air, the alveoli collapse and oxygen cannot enter the blood in the right amount. As a result, a person has severe shortness of breath and less oxygen reaches the organs than necessary. ARDS is the leading cause of death in new coronavirus infections.
According to reports, if a person with COVID-19 develops ARDS, then this usually happens like this: on the sixth-seventh day after the onset of symptoms, shortness of breath occurs, and on the second or third day after that, acute respiratory distress syndrome. This occurs, according to various sources, in 3-17% of cases.
The risk that pneumonia will end in ARDS is higher if the sick person is an older person, if he is an alcohol abuser, smoked earlier or smokes now, is undergoing chemotherapy or is obese.
True, ARDS occurs not only due to pneumonia (although this is the main reason), but also due to other lung injuries up to a blunt chest injury. Doctors began to notice such a state as far back as the time of the First World War, the name came to him in 1967, and the definition only in 1994.
The main thing that a person feels with ARDS is shortness of breath. He cannot finish the proposal without a breath, he does not have enough air. But shortness of breath often also occurs in less serious conditions, which, however, can gradually reach a severity that will be defined as ARDS. An accurate diagnosis is made by computed tomography (which in this regard is much better than conventional radiography, and especially fluorography) and the evaluation of other indicators related to lung function.
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Why is this syndrome especially common with COVID-19
The new coronavirus can enter the cells of the respiratory tract, alveoli, blood vessels, heart, kidneys and the gastrointestinal tract. Although the lungs still suffer the most. Affected cells produce many copies of the coronavirus and eventually die. All this triggers and supports the inflammatory response of the immune system.
Normally, the immune system itself over time suppresses this inflammation, and the person recovers. But with coronavirus infection more often than in many other cases, it happens that the inhibitory mechanisms of the immune system do not work as they should. In the worst case scenario, this leads to a condition called the “cytokine storm”. Then the whole body is captured, and even the kidneys and heart can be affected. And, of course, among other things, ARDS is developing. In other words, it is not the virus that launched the aggressive response that can take part in large-scale injuries, but the human immune system itself, which has gone out of control.
It’s very difficult to cope with ARDS
With ARDS, two problems must be solved in a good way: to ensure that the level of blood oxygen saturation is sufficient and that the immune system stops destroying the lungs. The first problem is better studied than the second, and there can be said to be a solution there.
Blood saturation with oxygen
Acute respiratory distress syndrome does not always mean that a person is breathing mechanical ventilation (mechanical ventilation). In fact, under certain conditions, other methods can be dispensed with, although still the standard tactic is mechanical ventilation. True, the apparatus does not always breathe for a person: it happens, it works in an auxiliary mode. Leaving a person without such help in the hope that the body will cope on its own is quite dangerous. In addition, if a person dies, then his death is likely to be painful.
From the post of New York resuscitator Eugene Pinelis:
“Mechanical ventilation - supporting therapy. An alternative to her is death by suffocation.
This is not a very honest polemical move, but I can. Have you seen how people die from suffocation? <…> I - saw. And I will always remember everyone. A patient with end-stage pulmonary fibrosis, for whom mechanical ventilation was indeed contraindicated, as he could not receive a lung transplant. Seniors with severe pneumonia who have chosen not to ventilate themselves. Morphine helps, but not completely. And you have to wait for him from the pharmacy. And see the breath forty-five times a minute (just try), blue lips, delirium or horror.
During the COVID-19 epidemic, we all saw this dozens of times. Patients escaping from the hands of doctors and nurses and stripping off oxygen masks. Or just concentrated only on breathing. On all these 45 breaths. In sixty seconds. When the whole body works together with the diaphragm, sometimes it seems that even the calf muscles. ”
If the standard version of mechanical ventilation does not help, a person can be placed on his stomach, continuing ventilation of the lungs (this is also proposed by the World Health Organization). So, apparently, the blood flow in the lungs is redistributed, and the blood flows through those areas in which oxygen can enter it.
On the subject: COVID-19 in asymptomatic form: why there is no temperature and whether the lungs suffer
In severe ARDS, drugs for neuromuscular blockade are still used and, rarely, nitric oxide. Although the benefits of these drugs are controversial. In these cases, the Russian Ministry of Health suggests using a mixture of helium and oxygen, but there is nothing like that in foreign recommendations, and, apparently, there are no grounds for using such tactics either.
In extreme cases, extracorporeal membrane oxygenation (ECMO) can be used, that is, passing the patient’s blood through an apparatus that enriches it with oxygen, takes carbon dioxide and returns it to humans. But such devices are rare and require a large number of specially trained personnel. In addition, the effectiveness of ECMO for new coronavirus infection is in doubt, although the World Health Organization suggests considering this option.
Building the immune system
As for the functioning of the immune system, now there are remedies that are supposed to work precisely and affect the necessary mechanisms. But, as is usually the case with COVID-19, there are still not enough good studies. In similar conditions - when the immune system behaves aggressively - some monoclonal antibodies (e.g., tocilizumab) are sometimes prescribed. They can reduce the level of substances involved in the inflammation process. There are small works that show the effectiveness of tocilizumab, but so far there are no truly reliable studies that would show the effectiveness of this approach for a new coronavirus infection. Apparently, if it works, then in severe cases, but at the same time before the development of ARDS.
More severe intervention can lead to the spread of the virus. Therefore, for example, glucocorticoids, which suppress the immune system, are recommended to be used only in extreme cases, and even then not all organizations.
There is another problem with this syndrome that makes the new coronavirus especially dangerous.
Even if a person has experienced ARDS, this does not mean that he will become the same in both the mental and physical sense. Approximately 40% of former patients have some degree of impaired thinking. Perhaps this is due to the fact that for some time the brain received insufficient oxygen. These people are more likely to experience depression, anxiety, and post-traumatic stress disorder. Parts of them are more difficult to withstand previous physical exertion, and the lungs usually work worse than before.
