Table 2 Outcomes
Overall (n = 450) | Facemask alone (n = 233) | Facemask combined with HFNO (n = 217) | Absolute differences (95% CI) | Relative risks (95% CI) | p value | |
|---|---|---|---|---|---|---|
Primary: lowest EtO2 within 2 min after intubation (%)a | 90 (87–92) | 89 (85–92) | 91 (88–93) | − 2.20 (− 3.21 to − 1.18) | – | < 0.001 |
Secondary: | ||||||
SpO2 at the end of preoxygenation (%) | 100 (100–100) | 100 (100–100) | 100 (100–100) | 0.02 (− 0.08 to 0.12) | 0.56 | |
First EtO2 after intubation (%)b | 91 (88–96) | 90 (87–96) | 92 (89–97) | − 1.64 (− 2.83 to − 0.45) | – | 0.004 |
Highest EtCO2 after intubation (%)c | 37 (34–40) | 37 (34–40) | 37 (33–41) | 0.83 (− 0.21 to 1.87) | – | 0.26 |
Lowest EtCO2 within 2 min after intubation (%)c | 35 (32–38) | 35 (32–38) | 35 (32–38) | 0.76 (− 0.22 to 1.73) | – | 0.38 |
First SpO2 after intubation (%)d | 100 (100–100) | 100 (100–100) | 100 (100–100) | − 0.56 (− 1.17 to 0.05) | – | 0.39 |
Lowest SpO2 during intubation and within 2 min after intubation (%)d | 100 (99–100) | 100 (99–100) | 100 (99–100) | − 0.64 (− 1.36 to 0.09) | – | 0.41 |
SpO2 ≤ 95% during intubation and within 2 min after intubation | 16/447 (3.6) | 14/232 (6.0) | 2/215 (0.93) | 0.05 (0.02 to 0.09) | 6.84 (1.54 to 30.5) | 0.004 |
Ease of use of preoxygenation (from 0 to 10)e | 9 (8–10) | 10 (9–10) | 8 (7–9) | 1.74 (1.36 to 2.11) | – | < 0.001 |
First-attempt success | 416/441 (94.3) | 210/225 (93.3) | 206/216 (93.4) | − 0.02 (− 0.06 to 0.02) | 0.68 (0.30 to 1.55) | 0.36 |
Excellent conditions of intubation | 253/406 (62.3) | 127/209 (60.8) | 126/197 (64.0) | − 0.03 (− 0.13 to 0.06) | 0.87 (0.58 to 1.31) | 0.51 |