BACKGROUND: This study is aimed to evaluate the effect of inspiratory muscle training (IMT) added to rehabilitation in patients with chronic obstructive pulmonary disease (COPD) who remain hypercapnic and use non-invasive ventilation after successful weaning. METHODS: Patients received rehabilitation and were randomized to inspiratory muscle or sham training for 4 weeks. The primary outcome was distance walked within 6 min. Secondary outcomes were inspiratory muscle strength, endurance, lung function, and blood gas levels. RESULTS: Twenty-nine patients participated in this study. Walking distance of the sham group increased from 93 +/- 52 m at baseline to 196 +/- 85 m at week 4 (p = 0.019, 95% CI 11 to 196 m). Patients in the IMT group significantly improved their walking distance from 94 +/- 32 to 290 +/- 75 m (p < 0.0001 (107 to 286 m); p = 0.04 (3 to 186 m) for between-group comparison). Patients in the IMT group increased their maximal inspiratory pressure from -35 +/- 8 to -55 +/- 11 cmH2O (p = 0.001; -6 to -33 cmH2O), while the increase in the sham group failed to reach significance (-29 +/- 10 to -37 +/- 13 cmH2O (-22 to 6 cmH2O)). Inspiratory power increased from 9.6 +/- 5.4 to 20.7 +/- 9.7 joules/min (2.6 to 19.5 joules/min, p = 0.003) in the IMT group, while no significant change occurred in the sham group (7.6 +/- 4.2 joules/min at study entry and 11.1 +/- 6.9 joules/min (-5.2 to 12.3 joules/min) at study end). CONCLUSIONS: Rehabilitation of successfully weaned patients with COPD and persistent hypercapnia significantly improves functional exercise capacity. Additional IMT significantly enhances functional exercise capacity and increases respiratory muscle strength and power.

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