Functional capacity assessment using the six-minute walk test incorporating dynamic ventilation in post-COVID-19 patients

Abstract

Introduction: The pandemic caused by the SARS-CoV-2 virus has presented itself as one of the biggest health challenges on a global scale at the beginning of this millennium. The scarcity of prognostic studies in patients with post-COVID-19 syndrome (PCS) shows the need to identify the main effects on the functional capacity in the short and medium term of these patients. In this sense, the assessment of lung function and structure and functional capacity in post-COVID-19 patients is essential to estimate the impact of the losses caused by the disease. Objectives: The objective of this study was to evaluate the effects of pulmonary rehabilitation (PR) on the dynamics of ventilation measured during the 6' walk test (6MWT) in patients with PCS and, secondarily, to evaluate the association of these findings with measurements of lung function and structure obtained at rest. Methods: This is a cross-sectional study, with quantitative evaluation of sample data. Initially, a clinical-functional assessment was carried out, including anthropometric measurements (weight, height and body mass index). These patients then underwent assessment of lung function through spirometry and impulse oscillometry system (IOS), analysis of lung ultrasound (LUS) parameters and assessment of functional capacity through the (6MWT) incorporated into the measurement of lung ventilation using the Spiropalm® (Spiropalm 6MWT, Cosmed, Rome, Italy). Results: Spirometry was abnormal in 21.2% and 31.3% of participants in the groups that performed RP (group RP) and that did not perform RP (group (NRP), respectively (p=0.36). IOS was abnormal in 28.6% and 66.7% of participants in the RP and NRP groups, respectively (p=0.003). USP was altered in 39.4% and 43.8% of participants in the RP and NRP groups, respectively (p=0.72). The distance covered in the 6MWT (6MWD) was greater in the RP group compared to the NRP group [437 ± 92 vs. 361 ± 79 m, p=0.001]. Dynamic hyperinflation was observed in 6.1% and 37.5% participants in the RP and NRP groups, respectively, with a significant difference in the inspiratory capacity ΔCI (p<0.001). The 6MWD correlated significantly with several IOS parameters and with ΔCI. There was no association between abnormal spirometry and 6MWD or between abnormal USP and 6MWD. Conclusion: In conclusion, patients with PCS undergoing RP perform better in the 6MWT, with higher 6MWD and less HD. In these patients, the 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 the IOS and the less HD there is, the better the performance in the 6MWT'.