RESPIRATORY CONSEQUENCES AFTER COVID-19 AND THE PHENOTYPES OF LUNG DIFFUSING CAPACITY DISORDERS IN THE POST-COVID-19 PERIOD
Authors: Glushkova T.V. ,   Ural Research Institute for Phthisiopulmonology (a branch of National Medical Research Centre of Phthisiopulmonology  and Infectious Diseases), Ekaterinburg, Russia, Leshchenko I.V. , Savelyev A.V. , Skornyakov S.N. , Filatova E.A. ,   Ural Research Institute for Phthisiopulmonology (a branch of National Medical Research Centre of Phthisiopulmonology  and Infectious Diseases), Ekaterinburg, Russia, Ural State Medical University, Ekaterinburg, Russia, LLC Medical Union “New Hospital”, Ekaterinburg, Russia,   Ural Research Institute for Phthisiopulmonology (a branch of National Medical Research Centre of Phthisiopulmonology  and Infectious Diseases), Ekaterinburg, Russia,   Ural Research Institute for Phthisiopulmonology (a branch of National Medical Research Centre of Phthisiopulmonology  and Infectious Diseases), Ekaterinburg, Russia, Ural State Medical University, Ekaterinburg, Russia,   Ural Research Institute for Phthisiopulmonology (a branch of National Medical Research Centre of Phthisiopulmonology  and Infectious Diseases), Ekaterinburg, Russia
Published: July 2024

Objective: to evaluate the respiratory system condition in patients after the novel coronavirus infection (СOVID-19) and describe the phenotypes of lung diffusing capacity disorders. Materials and methods. The study enrolled 89 patients after moderate-to-severe or severe coronavirus disease. The study consisted of five successive stages corresponding to day 50 (36–68), the 3rd, 6th, 12th and 18th month after the disease onset. On every stage we considered complaints, performed physical examination, assessed patients’ condition using the modified Medical Research Council (mMRC) dyspnea scale. Functional studies of the respiratory system (spirometry, body plethysmography, diffusing capacity of the lung for carbon monoxide (DLCO)) were performed on the 2nd, 3rd and 4th stage. Patients with DLCO < 80% were studied on the 5th stage. High-resolution computed tomography (HRCT) of the chest was performed on the 2nd, 3rd and 4th stages. Results. Dyspnea regression was observed from the 3rd to 5th stages of observation and corresponded to one score of mMRС dyspnea scale irrespective of the disease severity. The median values of spirometry parameters were within the norm on every stage. We detected decrease in the lung residual volume (RV) on the 2nd stage, on the 3rd stage and later no decrease in RV was detected. After 18 months (the 5th stage) patients after severe COVID-19 had DLCO < 80%. The risk factors for DLCO decrease to < 60% after 12 months (the 4th stage) were severe course of the disease, hospitalization to the resuscitation and intensive therapy department, high flow oxygen therapy, p < 0.05. According to HRCT data, in the lung tissue prevailed ground-glass opacities and parenchymatous stripes irrespective of the disease severity. Reticular changes and widened bronchial lumens after 12 months were associated with DLCO < 60%, p = 0.02 and p = 0.01 respectively. Conclusion. Considering the dynamics, DLCO, alveolar volume (VA) and the ratio of DLCO to VA (DLCO/VA), we established three phenotypes of lung diffusing capacity disorders: predominantly perfusion, predominantly ventilation, and ventilation perfusion. For each phenotype we determined functional values and CT patterns associated with COVID-19 severity and length of the post COVID-19 period.