Post-COVID-19 Dyspnea: The Role of Surfactant in Lung Diffusion

<bold>The aim:</bold> was to assess the role of surfactant dysfunction in lung diffusion capacity in patients (pts) with dyspnea in the post-acute phase of COVID-19. <bold>Materials and methods:</bold> Were observed 62 pts with dyspnea (49,3% men, age–55,6±9,8 yr) on 48(45;56) days after the onset of the first symptoms of COVID-19, who suffered severe course COVID-19 with in April-November 2021. Pts with any history of lung diseases, as well as pulmonary embolism were excluded. <bold>Methods:</bold> determination of lung diffusion capacity (assessment of alveolar volume(V_A), alveolo-capillary membrane diffusion (K_CO(CO transfer coefficient)), serum surfactant protein A (SP-A). Cluster analysis. <bold>Results:</bold> Cluster analysis showed that all pts can be divided into three clusters: сl.1 – pts with lower DLCO level, mainly due to decrease in V_A level, and higher level of SP-A; cl.2 – pts with lower DLCO level, mainly due to decrease of K_CO, and lower level of SP-A; cl.3 – pts with normal DLCO level including V_A and K_CO levels, lower SP-A levels (Fig. 1). <fig><object-id>erj;64/suppl_68/PA528/F1</object-id><object-id>F1</object-id><object-id>F1</object-id><graphic></graphic></fig> <bold>Conclusions:</bold> 1) in the post-acute period СOVID-19 pts with dyspnea may exhibit impaired diffusion capacity of the lungs because of decrease of alveolar volume; 2) impairment of alveolar volume can be the result of dysfunction of the surfactant system. This factor should be considered in the development of rehabilitation programs for these pts; 3) reduction of level of V_A in DLCO can be considered as a predictor of dysfunction of the surfactant system.