Effects of pulmonary rehabilitation on ventilation dynamics measured during exertion in patients with post-acute COVID-19 syndrome: A cross-sectional observational study.

Background: Pulmonary rehabilitation (PR) is recommended in people with post-acute COVID-19 syndrome (PACS), although there is a lack of studies evaluating its benefits via the most commonly used primary endpoint: the six-minute walk test (6MWT). This study evaluated the effects of PR on the dynamics of ventilation measured during the 6MWT in patients with PACS and, secondarily, evaluated the association of these findings with measures of lung function and structure.

Methods: This was an observational cross-sectional study of patients with PACS, in which 33 had undergone PR (PR-PACS group) and 32 had not undergone PR (NPR-PACS group). These patients underwent Spiropalm®-equipped 6MWT with measurement of inspiratory capacity (IC) to evaluate dynamic hyperinflation (DH). In addition, they performed spirometry, impulse oscillometry (IOS) and lung ultrasound (LUS).

Results: Spirometry was abnormal in 21.2% and 31.3% of participants in the PR-PACS and NPR-PACS groups, respectively (p = 0.36). IOS was abnormal in 28.6% and 66.7% of participants in the PR-PACS and NPR-PACS groups, respectively (p = 0.003). LUS was altered in 39.4% and 43.8% of the participants in the PR-PACS and NPR-PACS groups, respectively (p = 0.72). The 6-min walk distance (6MWD) was greater in the PR-PACS group than in the NPR-PACS group (p = 0.001]. HD was observed in 6.1% and 37.5% of participants in the PR-PACS and NPR-PACS groups, respectively, with a significant difference in ΔIC (p<0.001). The 6MWD correlated significantly with several IOS parameters and with ΔIC.

Conclusions: Patients with PACS undergoing PR perform better in the 6MWT, with a higher 6MWD and less HD. In these patients, IOS is able to distinguish the effects of PR that are not differentiated by spirometry or LUS. Furthermore, the better the respiratory mechanics assessed by IOS and the less DH there was, the higher the performance in the 6MWT.