Tiotropium and Simplified Detection of Dynamic Hyperinflation

Abstract Study objective: To detect dynamic hyperinflation (DH) by evaluating reduction in inspiratory capacity (IC) during metronome-paced hyperventilation (MPH) in patients with moderate-to-severe COPD, studied before and after treatment with tiotropium. Methods: IC and FEV 1 were measured before and immediately after MPH at two times resting the respiratory rate for 20 s in 60 COPD patients (28 men; mean age, 66 ± 10 years [± SD]) before and after 30 days of treatment with tiotropium bromide, 18 μg. Patients were encouraged to maintain a constant tidal volume during MPH. Results: At baseline, mean FEV 1 was 1.5 ± 0.1 L (± SE) [57 ± 1.6% of predicted], mean FVC was 2.6 ± 0.1L (77 ± 1.8% of predicted), and mean FEV 1 /FVC was 56 ± 1%. After 180 μg of aerosolized albuterol sulfate, mean FEV 1 was 1.7 ± 0.1 L (63 ± 1.5% of predicted) [p 1 /FVC was 58 ± 1%. Compared to baseline, after 30 days and 1.5 h after tiotropium there was an increase in IC of 0.18 ± 0.04L (p 1 of 0.13 ± 0.03 L (5.6 ± 0.8% of predicted; p = 0.0002); FVC of 0.22 ± 0.05 L (6.5 ± 1.3% of predicted; p 1 (− 0.05 ± 0.04 L; p = 0.2); and FVC (− 0.22 ± 0.03 L; p Conclusion: In patients with moderate-to-severe COPD, tiotropium did not reduce MPH-induced DH and reduction in IC, compared to baseline. However, because tiotropium induced bronchodilation and increased baseline IC, lower operational lung volumes may blunt the effect of MPH-induced DH. The noninvasive simplicity of MPH-induced DH provides a clinically useful screening surrogate to monitor changes in IC following treatment with tiotropium.