Assessing Lung Diffusion Capacity: Key to Understanding Dyspnea in Post-Acute COVID-19

<bold>The aim:</bold> to estimate the lung diffusing capacity in patients (pts) with dyspnea in the post-acute phase of COVID-19. <bold>Materials and methods:</bold> Were observed 77 pts with dyspnea (49,3% men, age–54,2±9,8) on 48 (45;56) days after the onset of the first symptoms of COVID-19, who suffered COVID-19-associated pneumonia with in 2021. Divided into subgr. based on disease severity: moderate (n=31), severe (n=44), critical (n=15). Pts with any history of lung diseases or pulmonary embolism were excluded. Methods:modified Borg scale for dyspnea, lung diffusion capacity. <bold>Results:</bold> Post-acute COVID-19 dyspnea severity correlated with acute phase severity (r=0.65,p<0.001). Lung diffusion impairment was evident in 52 pts (68.4%). In subgr.3, all pts had impaired lung diffusion, while in subgr.1 and 2 was 52.0% and 67.5% (p<0.05). DLCO levels were lowest in subgr.3, highest-in subgr.1 (p<0.05)(tabl.1). In subgr 2 and 3, V_A levels lower compared to K_CO, indicating diffusion capacity impairment due to decreased alveolar volume, not alveolar-capillary membrane changes. <fig><object-id>erj;64/suppl_68/PA1450/F1</object-id><object-id>F1</object-id><object-id>F1</object-id><graphic></graphic></fig> <bold>Conclusions:</bold> 1) impaired lung diffusion capacity is one of the key pathophysiological determinants of dyspnea in pts in post-acute COVID-19; 2) impaired lung diffusion capacity in pts after severe or critical illness, is often associated with significant reductions in alveolar volume. These pts should monitoring by a pulmonologist and have an individualized rehabilitation program developed.