The cumulative effect of long-acting bronchodilators, exercise, and inspiratory muscle training on the perception of dyspnea in patients with advanced COPD.
BACKGROUND
Dyspnea is a common complaint during daily activities in patients with advanced COPD. The mechanisms underlying dyspnea and the appropriate treatment strategies to relieve it are still not totally understood. We hypothesized that the perception of dyspnea (POD) may be modified by the accumulative effect of bronchodilator therapy, exercise, and inspiratory muscle training (IMT).


METHODS
Spirometry, submaximal exercise performance, inspiratory muscle strength and endurance, and the POD were assessed before and following three consecutive 6-week periods of therapy with a long-acting bronchodilator (LABD), the LABD plus exercise, and the LABD plus exercise plus IMT in 30 patients with moderate-to-severe COPD.


RESULTS
There was a small, statistically insignificant, increase in FEV(1) in the study group (mean [+/- SEM] increase, 1.42+/-0.3 to 1.49+/-0.4 L) following the LABD therapy period, and no additional increase following the two other periods of therapy. There was a significant increase (p<0.05) in the 6-min walk distance following the therapy period with the LABD plus exercise (mean increase, 252+/-41 to 294+/-47 m) and an additional small increase following the therapy period with the LABD plus exercise plus IMT period (mean increase, 252+/-41 to 302+/-49 m). The decrease in the POD was small and statistically not significant following the therapy periods with the LABD and the LABD plus exercise. The major and statistically significant decrease in the POD was noted following the therapy period with the LABD plus exercise plus IMT.


CONCLUSIONS
In patients with moderate-to-severe COPD, following sequential periods of therapy with the LABD, the LABD plus exercise, and the LABD plus exercise plus IMT, there is a cumulative benefit in the POD. The most significant improvement was associated with IMT and not with the LABD and exercise training. The FEV(1) was moderately increased following the therapy period with the LABD, and the addition of exercise has most affected the 6-min walk distance.