The endothelial NO synthase content in the blood serum of patients with coronavirus disease (COVID-19) with pneumonia in association with hemostatic parameters depending on the clinical course and its prognostic significance

Aim: to investigate the content of eNOS in the blood serum of patients with coronavirus disease (COVID-19) with pneumonia in association with hemostatic parameters and to determine its prognostic value in assessing the risk of oxygen dependence and death. Material and methods. There were 123 patients with COVID-19 with pneumonia under observation. All patients were examined and treated in accordance with the Order of the Ministry of Health of Ukraine No. 722 dated 28.03.2020. The eNOS content in the patients' serum was determined by enzyme-linked immunosorbent assay. Results. It was found that the content of eNOS in the blood serum of patients with COVID-19 with pneumonia at the time of hospitalization was 9.0 [7.0; 12.0] days lower (p < 0.001) than in healthy subjects. The development of oxygen dependence in patients with COVID-19 with pneumonia was accompanied by worsening of endothelial dysfunction and procoagulant changes, which was confirmed by a decrease in the content of eNOS in the blood serum (p < 0.001), an increase in the level of fibrinogen (p < 0.05) and D-dimer (p < 0.05). The threshold level of eNOS in the blood serum <= 327.09 pg/ml (AUC = 0.861, p < 0.001) was predictive of the onset of oxygen dependence. In patients with COVID-19 with pneumonia who subsequently died, at the time of hospitalization, eNOS levels were lower (p < 0.001) than in patients who recovered, which was combined with a higher level of D-dimer (p < 0.05) and its more frequent increase (p = 0.04) compared with patients who recovered. The eNOS content in the blood serum of patients with COVID-19 with pneumonia was correlated (p < 0.05) not only with the lethal outcome of the disease, but also with the formation of thrombotic complications, which occurred more often in patients with COVID-19 with pneumonia in the event of an adverse outcome (p = 0.0001). The threshold level of eNOS in the blood serum <= 201.75 pg/ml (AUC = 0.892, p < 0.001) was indicative of a high probability of death. Conclusion. The eNOS content in the blood serum of patients with COVID-19 pneumonia at the time of hospitalization is lower (p < 0.001) than in healthy individuals, and the degree of its decrease depends on the severity of the disease, the development of oxygen dependence and the subsequent outcome of this disease. Limiting levels of eNOS in the blood serum of patients with COVID-19 pneumonia, which are important for predicting the risk of developing oxygen dependence and fatal outcome of the disease, have been established.