The proportion of patients with a predetermined rise in the transcutaneous partial pressure of carbon dioxide (Ptco2) from baseline at 60 min
| High concentration O2 n (%) | Titrated O2 n (%) | RR (95% CI) | p Value | |
| Change in Ptco2 ≥4 mm Hg | 22 (44%) | 10 (19%) | 2.3 (1.2 to 4.4) | 0.006 |
| Change in Ptco2 ≥4 mm Hg and Ptco2 ≥38 mm Hg | 17 (34%) | 4 (8%) | 4.5 (1.6 to 12.5) | 0.001 |
| Change in Ptco2 ≥8 mm Hg | 11 (22%) | 3 (6%) | 3.9 (1.2 to 13.1) | 0.016 |