Lack of protective effect of tiotropium vs induced dynamic hyperinflation in moderate COPD.

STUDY

OBJECTIVE

Novel evaluation of protective effect of tiotropium against induced dynamic hyperinflation (DH) during metronome paced hyperventilation (MPH) in moderate COPD.

METHODS

Prospective, randomized, double-blind, placebo control, crossover study. Lung function measured pre/post MPH at 30 breaths/min for 20 s in 29 (18 M) COPD patients (GOLD Stage 2) age 70±9 yr (mean ± SD) before and after 30 days of 18 μg tiotropium bromide vs placebo. Lung CT scored for emphysema (ES).

RESULTS

At baseline post 180 μg aerosolized albuterol sulfate, FEV(1): 1.8±0.6 L (69±6% pred) and ≥60% predicted in all, and 14 of 29 had FEV(1) (L) ≥70% predicted with FEV(1)/FVC 58±8%. After 29 days + 23 h post tiotropium (trough) there was significant decrease only in FRC/TLC% (p=0.04); after 30 days + 2 h post tiotropium (peak) significant increase only in FEV(1) (L) (p=0.03) compared to placebo. Results post MPH induced DH at baseline and after 30 days and 2 h post placebo or tiotropium were similar with decrease in IC 0.44±0.06 L (p<0.001). Correlation between ES and increased FEV(1) (L) at peak tiotropium: r=0.19, p=0.96 and decreased FRC/TLC% at trough tiotropium: r=-0.26, p=0.36.

CONCLUSION

In moderate COPD, tiotropium did not reduce MPH induced DH and reduction in IC. However, at peak tiotropium, there was significant bronchodilation in FEV(1) (L) and at trough a decrease in FRC/TLC% compared to placebo despite varying emphysema.