Most people who have contracted Sars-CoV-2 have a mild infection. Some have no symptoms, others only a slight fever, body aches and possibly cough. You do not have to go to the clinic and usually do not need outpatient medical help. Their share is currently estimated to be at least 80 to 85 percent. However, since the number of unreported cases is very large despite the fact that tests have been expanded, the percentage of harmless or even asymptomatic courses is probably even higher.
In CT, atypical pneumonia is often recognized by network-like changes
However, some patients with Covid-19 are so bad that they need hospital treatment. You are seriously ill, feel weak and exhausted, have a fever and complain of new shortness of breath. Initially, pain and fever-lowering drugs are given and any fluid deficits are compensated for. But then suddenly the air stays away more and more often.
“Who actually needs ventilation is decided individually – based on well-established algorithms that we can now use for the optimal treatment of patients with Covid-19,” says Stefan Kohlbrenner, senior physician for anesthesia at the Diakoniekrankenhaus in Freiburg and also for the intensive care unit there responsible. “The clinical picture and the extent of the symptoms are very important, as is the oxygen saturation in the blood.” If an elderly patient in poor general condition is admitted to the clinic with fever and shortness of breath, it is now likely during the corona pandemic that he will not be able to do without breathing assistance.
In addition, criteria such as the CRB-65 index, which measures the degree of confusion, an increased respiratory rate and low blood pressure at age 65 and older are taken into account as a basis for the prognosis and further clinical decisions in pneumonia. The situation is similar with the qSOFA score, which can be used to estimate the risk of involvement of other organ systems and the risk of blood poisoning (sepsis).
A number of experts are currently recommending that patients with fever, cough and general weakness be examined in the clinic using computer tomography (CT) because the images show specific changes. Atypical pneumonia, as can be caused by Sars-CoV-2, but also other viruses and fungi, often gives a typical picture in CT. While “classic” bacterial pneumonia, such as pneumococcal infection, tends to result in widespread lung involvement, mesh-like changes are often seen in atypical pneumonia.
If oxygen saturation drops, the proportion of hemoglobin in the blood loaded with oxygen decreases, which means that gas exchange in the lungs and thus breathing no longer work as well. For healthy people, the value is usually between 97 and 100 percent. With a saturation of 88 to 90 percent, the indication for ventilation is often given, depending on the general condition of the patient and possible other diseases.
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“The mildest form to support breathing is oxygen insufflation through a mask or nasal cannula,” says intensive care doctor Kohlbrenner. “The air supplied is enriched with more oxygen.” These patients receive additional oxygen through a thin tube in the nose or a mask. In hospitals, such a connection is usually located in the wall next to the bed, for patients with respiratory problems, therapy is also possible at home with the help of oxygen cylinders.
The next level of escalation is called “non-invasive ventilation” and also takes place using a mask that is firmly strapped onto the face. A respirator can be used to administer pressure in addition to oxygen. These interventions almost always take place in an intensive care unit. “For many seriously ill Covid-19 patients, however, it is not enough. Last week, mask ventilation was sufficient for one patient, after which the patient was able to continue treatment in the normal ward,” said Kohlbrenner. However, the possible contamination of the environment with aerosols should be taken into account here, the masks have to be removed again and again, for example for nursing interventions.
After three or four days of artificial respiration, there is a risk of weakening the respiratory muscles
Gas exchange in the lungs can be supported even more effectively if patients are ventilated via a tube. To do this, a plastic tube is pushed over the throat into the trachea. The patient must be placed in an artificial coma for intubation. He can then no longer swallow and cough on his own, which promotes the development of additional pneumonia from bacteria. This “bacterial superinfection” is often the reason for a severe, possibly fatal course.
“Invasive ventilation is the most effective,” says intensive care specialist Kohlbrenner. “But it is non-physiological and also has side effects, sometimes causing additional lung damage.” A previously healthy 50-year-old can survive two or three days of treatment without long-term consequences. However, the risks increase with increasing duration.
Well-coordinated teams in the intensive care unit know how to provide ventilation that is as gentle on the lungs as possible by avoiding high pressure differences and large ventilation surges. Sometimes collapsed or glued air sacs are stretched too violently. “All of this acts as an inflammatory stimulus that can exacerbate the problems of the lungs,” says Kohlbrenner. The body then produces inflammatory substances that quickly affect other organs. Ultimately, however, artificial ventilation remains unnatural.
In addition, after three or four days of artificial respiration, there is a risk of weakening the auxiliary breathing muscles and the diaphragm. Older patients often take longer to be weaned from support. “It is necessary to weigh up every day whether patients need to be ventilated further or not,” says Kohlbrenner. “Pneumonia is general, and even more so in the form of Covid-19, a complex disease that can also affect other organs. How long it takes for ventilation to take place and how the disease will proceed cannot be predicted in general. Major factors are important factors Age, general condition and the patient’s previous illnesses. “
For future work in intensive care units, this also means that car manufacturers may be able to switch to the production of ventilators. However, teaching medical students and other assistants requires considerable additional effort. For optimal treatment, fine-tuning in the team is important and the complex evaluation of positioning, pressure, tidal volume, accompanying circumstances and, if necessary, the therapy of other organ failures. It is not enough to be able to press buttons on the ventilator.