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

ABSTRACT

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.