Effects of training with heliox and noninvasive positive pressure ventilation on exercise ability in patients with severe COPD.

Study Objectives: We sought to determine whether breathing heliox or using nasal noninvasive positive pressure ventilation (NIPPV) would produce immediate improvements in exercise capability in patients with COPD, and whether training for 6 weeks with one of these modalities would result in greater exercise improvement than with training unassisted.

Setting: US military medical center.

Methods: Thirty-nine patients with severe COPD (mean FEV1 of 33.