Evaluation of functional capacity in patients with chronic obstructive pulmonary disease using the AVD-Glittre test incorporating pulmonary ventilation measures

Abstract

Introduction: Chronic obstructive pulmonary disease (COPD) is recognized as a condition with several pulmonary and extrapulmonary pathophysiological mechanisms that contribute to the burden of the disease. The inflammatory process often leads to airflow limitation and lung hyperinflation (LH). In addition to being a “treatable trait”, LH is an important determinant of exercise limitation, as it interferes with the morbidity and mortality of COPD. Objective: To evaluate the functional exercise capacity of individuals with COPD incorporating measures of dynamic ventilation and to identify the contributors to TGlittre-induced HD, especially the role of small airways disease. Methods: This is a cross-sectional observational study carried out at the Pulmonary Function Laboratory of the Pulmonology Service of the Piquet Carneiro University Polyclinic of the State University of Rio de Janeiro. Fifty-four patients diagnosed with COPD, of both sexes, were evaluated. Eligible participants completed the Saint George's Respiratory Questionnaire (SGRQ) quality of life questionnaire and the COPD Assessment Test (CAT). Additionally, patients underwent pulmonary function tests, including spirometry and impulse oscillometry (IOS). Finally, participants underwent functional assessment during exercise using the Glittre-AVD Test (TGlittre), which incorporated pulmonary ventilation measurements using Spiropalm®. Results: In the TGlittre, 30 (55,6%) participants showed DH at the end of the test (DH group), while 24 (44,4%) did not (NDH group). Although participants in the HD group took longer to complete the TGlittre tasks, there was no statistical difference between the two groups (145 ± 35 vs. 139 ± 23 % predicted, p=0.50). Regarding IOS, this exam was altered in 27 (90%) participants in the DH group and in only 9 (37.5%) in the NDH group (p<0.0001), with the DH group presenting higher values in the area under the reactance curve (Ax) and resonance frequency (Fres). The median values of Fres [(8 (4.3–17.9) vs. 2.8 (2.3–4.7)] and Ax [(24.7 (17–46) vs. 6.1 (4–9)] were higher in the DH group, with significant differences between them (p<0.0001 for both variables). DH correlated significantly with Fres (rs=-0.604, p<0.0001), Ax (rs=-0.652, p<0.0001) and several domains of the SGRQ and CAT scores. In the multivariable regression analysis, Fres and Ax explained 49% of the variability of DH. Thus, COPD patients who undergo DH during TGlittre have more altered IOS. In these patients, the more severe the DH, the worse the IOS parameters, the greater the impact of symptoms and the more deteriorated the realth-related quality of life. Furthermore, small airway disease strongly explains the DH in this patient population. Conclusion: Patients with COPD who undergo DH during TGlittre present more alterations in RO. In these patients, the more pronounced the DH, the worse the RO parameters, the greater the symptom impact, and the more deteriorated the QoL.Furthermore, SAD strongly explains DH in this patient population.