Dynamics of Functional Parameters of the Respiratory System in Patients with Various Forms of COVID-19

Abstract. The relevance of the problem is due to the high incidence of post-COVID syndrome, characterized by the persistence of respiratory symptoms even after a mild course of infection. According to meta-analyses, 30–50 % of patients who have had COVID-19 experience various disorders of external respiration function (ERF) within 6–12 months after the acute phase of the disease. Objective: to assess the dynamics of external respiration function and exercise tolerance in patients with various forms of COVID-19 during a 12-month observation period. Material and methods. A total of 177 patients were examined: 67 with mild COVID-19 pneumonia (group I), 60 with COVID-19 ARVI (group II), and 50 healthy individuals (control). Depending on the development of post-COVID syndrome, patients were divided into subgroups: IA (n = 32), IIA (n = 28) - with the syndrome and IB (n = 35), IIB (n = 32) – without it. The assessment was carried out in the first 72 hours, after 2 weeks, 3 and 12 months. Spirometry indicators and the results of the six-minute step test (6-MST) were studied. Statistical processing was performed using the IBM SPSS Statistics for Windows version 23 package (International Business Machines Corporation, U.S.A.). Results. In patients of group I, a significant decrease in the parameters of external respiration function was revealed relative to group II: vital capacity – by 1.36 times, FEV1 – by 1.89 times, Tiffeneau index – by 1.38 times (p <0.001). In the subgroups with post-COVID syndrome, 2 weeks after the onset of the disease, a more pronounced deterioration in the parameters was noted relative to patients without post-COVID syndrome: a decrease in FEV1 – by 1.11 times (p <0.001). When assessing the 6-MSHT, in patients of subgroup IA, the distance decreased to 287.12 ± 115.34 m (FC III), in patients of subgroup IIA, the distance was 549.28 ± 27.06 m (FC I). After 12 months, 56.25% of patients in subgroup IA and 53.57% of subgroup IIA retained FC I, while all patients in subgroups IB and IIB reached FC 0. Conclusion. The development of post-COVID syndrome is associated with more profound and persistent impairments of external respiratory function, requiring long-term rehabilitation.