TY - JOUR T1 - Lung diffusing capacities for nitric oxide and carbon monoxide at rest and post-walking in long COVID JF - ERJ Open Research JO - erjor DO - 10.1183/23120541.00363-2022 SP - 00363-2022 AU - Giovanni Barisione AU - Vito Brusasco Y1 - 2022/01/01 UR - http://openres.ersjournals.com/content/early/2022/10/27/23120541.00363-2022.abstract N2 - Background About one third of long COVID patients reports breathlessness and fatigue even during activities of daily living. We hypothesized that abnormalities of combined lung diffusing capacity for nitric oxide (DLNO) and carbon monoxide (DLCO) at rest or after mild exercise are associated with breathlessness in patients with long COVID.Methods Single-breath combined DLNO and DLCO were measured at rest and immediately after a short bout of treadmill exercise simulating ordinary walking in 32 Caucasian patients with long COVID and dyspnea at rest. Twenty subjects served as a control group.Results At rest, combined DLNO, DLCO, and alveolar volume (VA) were significantly lower in long COVID than in controls, with DLNO and DLCO being below the limits of normal in 69% and 41% of cases, respectively. Mean values of DLNO/VA and DLCO/VA in long COVID patients were less than controls yet, in only 22% and 12% of long COVID patients the values of DLNO/VA and DLCO/VA were below the limits of normal. After treadmill, DLNO, DLNO/DLCO, VA and heart rate increased significantly without differences between groups. DLNO remained below the limit of normal in 47% of long COVID.Conclusion These data suggest localized discrete loss of lung units in about half of long COVID patients, not completely explained by loss of VA or of alveolar-capillary recruitment during exercise.FootnotesThis manuscript has recently been accepted for publication in the ERJ Open Research. It is published here in its accepted form prior to copyediting and typesetting by our production team. After these production processes are complete and the authors have approved the resulting proofs, the article will move to the latest issue of the ERJOR online. Please open or download the PDF to view this article.Conflict of interest: The authors have nothing to disclose. ER -