Correlations Between Oxygen Consumption, Ventilatory Mechanics, and Lung Ultrasound in Individuals with Post-COVID Syndrome

Introduction: Since COVID-19 primarily targets the respiratory system, it is essential to longitudinally monitor functional capacity and pulmonary function in individuals with post-COVID syndrome (PCS). This study aimed to evaluate the functional capacity of individuals with PCS during exercise using cardiopulmonary exercise testing (CPX) and examine its association with spirometry, impulse oscillometry (IOS), and lung ultrasound (LUS) parameters. Methods: Sixty individuals participated in this study. We assessed CPX, which measured peak oxygen consumption (VO₂peak), in addition to IOS, spirometry, and LUS. Results: The mean VO₂peak was 18.4 ± 5.9 mL/kg/min. Significant negative correlations were found between VO₂peak and the following parameters: age (r_s = −0.465, p = 0.0002), body mass index (BMI, r_s = −0.354, p = 0.0056), resonance frequency using IOS (r_s = −0.312, p = 0.0193), and LUS aeration score (rs = −0.261, p = 0.0439). Conclusions: Patients with PCS undergoing CPX demonstrated impaired functional capacity. In these individuals, higher age and BMI were associated with lower VO₂peak. Furthermore, alterations in LUS and IOS may also be linked to reduced VO₂peak. These findings are promising, as they were obtained using a low-cost device. Further studies are needed to investigate the factors that influence oxygen consumption in PCS.