| Baseline | Air | Oxygen | p Value* | NIV | p Value† | |
| Mean Spo2 for TST (%) | 90 (4) | 89 (5) | 93 (2) | 0.03 | 92 (3) | 0.13 |
| Minimum Spo2 for TST (%) | 76 (9) | 75 (15) | 82 (6) | 0.24 | 79 (9) | 0.42 |
| Min av Spo2 for TST (%) | 89 (4) | 88 (6) | 92 (1) | 0.03 | 91 (2) | 0.12 |
| TST with Spo2 <90% (%) | 38 (43) | 48 (50) | 10 (9) | 0.03 | 23 (34) | 0.13 |
| Mean Ptcco2 TST (mm Hg) | 58 (3) | 62 (13) | 62 (10) | 0.92 | 53 (6) | 0.02 |
| Max Ptcco2 TST (mm Hg) | 68 (12) | 74 (19) | 72 (11) | 0.62 | 58 (7) | 0.005‡ |
| ΔPtcco2 (mm Hg) | 4.5 (1.6) | 4.9 (2.6) | 5.5 (3.6) | 0.45 | 2.7 (1.5) | 0.02‡ |
| ΔPaco2 (mm Hg) | 1.3 (3.9) | 2.0 (2.3) | 6.0 (4.2) | 0.07 | −1.3 (4.1) | 0.07‡ |
| Mean RR (breaths/min) | 23 (6) | 23 (5) | 22 (3) | 0.83 | 23 (5) | 0.74 |
| Mean HR (beats/min) | 78 (15) | 73 (11) | 70 (18) | 0.37 | 64 (15) | 0.05 |
Values are mean (SD).
*Mean difference from baseline (oxygen vs air).
†Mean difference from baseline (NIV vs air).
‡p<0.02, mean difference from baseline (NIV vs oxygen).
HR, heart rate; mean RR, mean respiratory rate during slow wave sleep; min av, minimum average; NIV, non-invasive positive pressure ventilation; Paco2, arterial carbon dioxide pressure; ΔPaco2, change in arterial carbon dioxide pressure from evening to morning; Ptcco2, pressure of transcutaneous CO2; ΔPtcco2, average rise in Ptcco2 from non-rapid eye movement to rapid eye movement sleep; Spo2, oxygen saturation by pulse oximetry; TST, total sleep time.