Consequences of SARS-COV-2 Pneumonia on Lung function

Abstract

<b>Background:</b> COVID-19 pneumonia impairs functional respiratory parameters. <b>Objective:</b> To characterize the impact of COVID-19 pneumonia on lung function. <b>Methods:</b> We took measurements of Lung volumes (TLC), lung diffusion capacity for carbon monoxide (DLCO) alveolar volume (VA), transfer coefficient (KCO), and 6-min walking test (6MWT) in patients hospitalized between March and April 2020, at 3 months after discharge. Patients with impaired diffusion and/or restrictive syndrome were re-evaluated at 6 months with global spirometry and chest HRCT scan. <b>Results:</b> 40 patients have been recruited and divided in two groups: patients with normal functional tests (Group A-48%) and patients with restrictive syndrome or decreased diffusion (Group B-52%). In GroupB: 9 patients showed desaturation during 6MWT. Higher differences for cough (p&lt;0.05), oxygen therapy, and mechanical ventilation (p&lt;0.001-p&lt;0.05) have been found. Always in Group B, 3 patients had pure restrictive syndrome (Group 1); 12 had Volumes and DLCO decreased (Group 2); 6 had isolated drop in DLCO (Group 3). At 6 months in Group 1, only one patient had normalized TLC, VA, and DLCO. In Group 2, functional parameters increased significantly (p&lt;0.01) but only one patient reached normal values. In Group 3, DLCO improved reaching normal values in 50% of patients. Correlations between chest CT severity score and TLC (p&lt;0.02), DLCO (p&lt;0.01), VA (p&lt;0.02) were significant with highest r2 index for DLCO (r2=0.40). <b>Conclusion:</b> Nearly 50% of patients did not present functional deficit in the post-critical phase. Most with abnormal lung function improved, but only 20% reached normal values at 6 months. Identification of these subjects might be useful to maximize pulmonary function recovery.