Noninvasive mechanical ventilation improves endurance performance in patients with chronic respiratory failure due to thoracic restriction

Objective: Treatment with noninvasive mechanical ventilation (NMV) alleviat es hypoventilation and improves gas exchange in patients with chronic respi ratory failure (CRF) due to thoracic restriction. However, little is known about the effects of NMV on respiratory and peripheral muscle endurance. Design: Prospective case-control study. Subjects: Ten patients in clinically stable condition (age, 53.5 +/- 8.2 ye ars [mean +/- SD]) with mild-to-moderate CRF due to thoracic restriction (P co(2) between 45 mm Hg and 55 mm Hg) were treated with NMV during the night for 3 months. Ten matched patients (age, 52.2 +/- 9.5 years) receiving 3 m onths of normal care without NMV served as a control group. Intervention and measurements: After a 3-day period of familiarization with the endurance tests, all patients pet-formed a baseline preintervention in spiratory threshold loading test, cycle ergometer test, and shuttle walking test on the same day. The endurance tests were then repeated following the 3-month intervention period. Results: NMV was used on average for 7.1 +/- 0.9 h/d during the 3-month per iod. There was a significant improvement in endurance time (p < 0.0001) in all three endurance tests in the NMV group compared with the control group. In the NMV group, endurance time increased by 278 +/- 269% during the insp iratory threshold loading test, by 176 +/- 159% during the cycle ergometer test, and by 32 +/- 22% during the shuttle walking test. Significant improv ements (p < 0.01) in both Po-2 and Pco(2) were also observed in the NMV gro up but not in the control group. Conclusions: Three months of treatment with NMV increases both respiratory and peripheral muscle endurance in patients with CRF due to thoracic restri ction.