Post-tuberculosis lung disease: functional impairment assessed by respiratory oscillometry, muscle strength and exercise capacity

Post-tuberculosis lung disease (PTLD) is a recently identified disease that presents complex and heterogeneous sequelae, introducing respiratory changes that are not fully understood. Respiratory oscillometry allows detailed analysis of respiratory mechanics with only tidal-volume breathing. The hypothesis is that oscillometry may improve our knowledge about pathophysiological changes in PTLD. This observational study included 40 participants: 20 controls and 20 with PTLD. The volunteers underwent traditional pulmonary function tests, oscillometry, manovacuometry, and the six-minute step test (6MST), assessing functional exercise capacity. Characterizing the burden of these sequelae included using questionnaires to evaluate abnormalities in quality of life and the severity of dyspnea. Our sample presented spirometric abnormalities in 75% of patients, with a predominance of obstructive ventilatory disorder. Oscillometric analysis demonstrated a significant increase in total airway resistance ( p < 0.001), a significant reduction in ventilation homogeneity ( p < 0.0001), a reduction in the homogeneity of elastic properties ( p < 0.001), dynamic compliance ( p < 0.001), and a significant increase in the total mechanical load of the respiratory system ( p < 0.0001). Functional tests showed expiratory muscle weakness ( p < 0.0001) and worse performance in the 6MST ( p < 0.01). Correlation analysis showed that abnormalities identified by oscillometry were correlated with spirometric ( p < 0.0001) and plethysmographic ( p < 0.0001) changes, as well as reduced 6MST performance ( p < 0.0001), respiratory pressures ( p < 0.0001), quality of life ( p < 0.016), and increased dyspnea severity ( p < 0.008). PTLD alters several aspects of respiratory mechanics. These changes were clarified using respiratory oscillometry, thereby improving our understanding of the pathophysiology of this recently described and poorly understood disease. Furthermore, the study suggests the clinical utility of oscillometry in evaluating PTLD as an alternative or complementary method to spirometry for assessing respiratory mechanics.