Maximum Voluntary Ventilation and Its Relationship With Clinical Outcomes in Subjects With COPD

BACKGROUND: Previous studies have reported that maximum voluntary ventilation (MVV) may be better associated with commonly used outcomes in COPD than FEV₁ and may provide information on respiratory mechanics. In this study, we aimed to investigate the relationship between MVV and clinical outcomes in COPD and to verify whether MVV predicts these outcomes better than FEV₁.

METHODS: We conducted a cross-sectional study involving individuals with COPD. Lung function was assessed with spirometry; maximum inspiratory and expiratory pressures (P_Imax and P_Emax, respectively) were assessed with manuvacuometry; and functional exercise capacity was assessed with the 6-min-walk test (6MWT). Dyspnea was assessed with the modified Medical Research Council (mMRC) scale; functional status was assessed with the modified Pulmonary Functional Status and Dyspnea Questionnaire (PFSDQ-m); and health status was assessed with the COPD Assessment Test (CAT). Correlations were verified with the Spearman coefficient, and stepwise multiple linear regression models investigated the predictors of clinical outcomes.

RESULTS: Our study included 157 subjects: 82 males; median (interquartile range) age 66 (61–73) y; FEV₁ 46 (33–57) % predicted; 6MWT 86 (76–96) % predicted; PFSDQ-m total score 34 (14–57); and CAT total score 13 (7–19). Moderate correlations were found between MVV and P_Imax (r = 0.40), 6MWT (r = 0.50), mMRC (r = –0.56), and total scores on the PFSDQ-m (r = –0.40) and the CAT (r = –0.54). In the regression models, MVV was a predictor of almost all clinical outcomes, unlike FEV₁.

CONCLUSIONS: MVV correlates moderately with clinical outcomes commonly used in the evaluation of individuals with COPD, and MVV is a better predictor of respiratory muscle strength, functional exercise capacity, and patient-reported outcomes than FEV₁.