Effect of fluticasone/salmeterol combination on dyspnea and respiratory mechanics in mild-to-moderate COPD

Abstract

The purpose of this exploratory physiological study was to evaluate the effects of inhaled fluticasone/salmeterol combination (FSC) on sensory and physiological responses to exercise in subjects with mild-to-moderate COPD. In a randomized, double-blind, placebo-controlled, crossover study, subjects underwent 6-week treatments with FSC or placebo (PLA). Detailed pulmonary function and constant-work rate cycle exercise tests were performed following each treatment period. Fifteen subjects completed the study (mean ± SD): age 64 ± 10 years; smoking history 47 ± 29 pack-years; post-bronchodilator forced expiratory volume in 1 s 86 ± 15 %predicted (10 mild and 5 moderate COPD); peak incremental oxygen uptake 71 ± 16 %predicted. Compared with PLA, FSC treatment was associated with improved: FEV1 by 0.23 ± 0.18 L; inspiratory capacity by 0.18 ± 0.23 L; functional residual capacity by -0.28 ± 0.30 L; and specific airways resistance by -4.6 ± 4.5 cmH2O s (all p < 0.01). There were no significant changes in dyspnea intensity throughout exercise and endurance time did not change significantly (1.2 ± 3.0 min, p = 0.149). Following FSC, inspiratory capacity at rest and throughout exercise increased by 0.2-0.3 L with concomitant increases in tidal volume and ventilation (p < 0.05). Compared with PLA, the work of breathing and the ratio of respiratory muscle effort to tidal volume improved with FSC during exercise (p < 0.05). In mild-to-moderate COPD, FSC was associated with significant improvements in airway function at rest and during exercise. Despite important mechanical improvements, there were no significant effects on dyspnea intensity and exercise endurance.