Functional and Radiological Assessment of the Respiratory System in Patients with Impaired Lung Diffusion Capacity in the Post-COVID Period

The objective: to evaluate functional and radiological data of the respiratory system assessment in patients with impaired lung diffusion capacity in the post-COVID period. Subjects and Methods. Clinical, functional and radiological data were analyzed and compared in the patients divided into two groups according to the degree of lung diffusion capacity (LDC) impairment measured by carbon monoxide (Dlco) after 180 (135–196) days from the onset of acute symptoms of COVID-19: Group 1 included patients with Dlco of 80–60%, and Group 2 included patients with Dlco less than 60%. The lung functions were assessed by spirometry, body plethysmography and the Dlco level measurement. The data of CT scans of patients performed in the acute period of COVID-19, after 93 (89–103) days and 180 (135–196) days from the onset of acute symptoms were analyzed. Results. The patients of Group 2 developed a severe form of COVID-19 statistically significantly more often, they required high-flow oxygen therapy (HFO) and stayed in the intensive care unit (ICU): 13/20 (65%), 11/20 (55%), 10/20 (50%) versus 8/24 (33,3%), 2/24 (8,3%) and 3/24 (13,5%) in the patients of Group 2, respectively. The level of Dlco (%) after 93 (89–103) days and 180 (135–196) days in Groups 1 and 2 made 66 (64–71) and 71 (67–73) versus 45 (41–53) and 51(47–58), respectively ( p <0,05). Honeycombing changes in the lungs were detected by chest CT only in the patients of Group 2 – 16.7% on 93 (89–103) and 180 (135–196) days of observation, respectively. Conclusion. A severe form of COVID-19, stay in the ICU and additional oxygen support are the factors indicating an unfavorable functional state of the respiratory system and presence of irreversible changes in the lung tissue in the post-COVID period.