| Baseline | Air | Oxygen | NIV | |
| pH | 7.38 (0.02) | 7.38 (0.03) | 7.39 (0.02) | 7.39 (0.03) |
| Paco2 (mm Hg) | 52 (4) | 52 (7) | 51 (7) | 50 (5) |
| Pao2 (mm Hg) | 63 (5) | 64 (7) | 66 (12) | 62 (6) |
| HCO3 (mmol/l) | 30 (2) | 30 (3) | 30 (4) | 30 (2) |
| Sao2 (%) | 93 (3) | 93 (3) | 94 (4) | 92 (4) |
| FEV1 (% pred) | 35 (8) | 32 (10) | 32 (9) | 33 (9) |
| FVC (% pred) | 60 (11) | 54 (13) | 54 (15) | 58 (15) |
| RV/TLC (%) | 59 (8) | 64 (9) | 64 (11) | 63 (10) |
| Shuttle Walk Test (m) | 434 (198) | 381 (132) | 403 (114) | 459 (144)* |
Values are mean (SD).
*p<0.02, mean difference from baseline (NIV vs air).
FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity; NIV, non-invasive positive pressure ventilation; Paco2, arterial carbon dioxide pressure; Pao2, arterial oxygen pressure; RV, residual volume; Sao2, arterial oxygen saturation; TLC, total lung capacity.