| Air | Oxygen | Mixed linear model estimates of differences | p Value | |||
| Baseline (n = 24) | 20 min (n = 24) | Baseline (n = 23) | 20 min (n = 23) | Estimate (95% CI) | ||
| Ptco2 (mm Hg) | 48.6 (4.0) | 47.7 (5.4) | 48.7 (3.8) | 52.7 (6.5) | 5.0 (3.1 to 6.8) | <0.001 |
| Ptco2 (kPa) | 6.46 (0.53) | 6.34 (0.72) | 6.48 (0.51) | 7.01 (0.86) | 0.67 (0.41 to 0.9) | |
| RR (bpm) | 15.8 (3.6) | 15.7 (4.4) | 15.6 (3.8) | 14.7 (3.8) | −0.9 (−2.4 to 0.67) | 0.25 |
| MV (l/min) | 9.6 (3.3) | 9.0 (3.4) | 10.1 (2.9) | 8.0 (3.3) | −1.4 (−2.6 to −0.11) | 0.03 |
| Vd/Vt | 0.58 (0.06) | 0.59 (0.08) | 0.57 (0.06) | 0.65 (0.06) | 0.067 (0.035 to 0.10) | <0.001 |
MV, minute ventilation; Ptco2, transcutaneous carbon dioxide tension; RR, respiratory rate, Vd/Vt, dead space to tidal volume ratio.
All values are mean (SD).