Table 3.
Time (min) to reach SaO2 90% and 40% during apnoeic oxygenation for different end-tidal oxygen fractions in the subjects in labour. BMI 24/35/40/45/50, body mass index 24/35/40/45/50 kg m−2, respectively; FiO2, inspired fraction of O2; HFNO, high flow nasal oxygen therapy; SaO2, arterial oxygen saturation.
| End-tidal oxygen fraction (%) | BMI24 and labour |
BMI35 and labour |
BMI40 and labour |
BMI45 and labour |
BMI50 and labour |
||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Closed glottis | FiO2 21% | HFNO | Closed glottis | FiO2 21% | HFNO | Closed glottis | FiO2 21% | HFNO | Closed glottis | FiO2 21% | HFNO | Closed glottis | FiO2 21% | HFNO | |
| Time from onset of apnoea to SaO290% (min) | |||||||||||||||
| 60 | 3.1 | 3.3 | 22.7 | 2.4 | 2.6 | 11.4 | 2.5 | 2.6 | 8.6 | 2.4 | 2.4 | 4.9 | 2.0 | 2.2 | 3.7 |
| 70 | 3.6 | 3.8 | 23.7 | 2.8 | 3.0 | 12.6 | 2.7 | 2.8 | 9.4 | 2.6 | 2.6 | 5.5 | 2.2 | 2.4 | 4.0 |
| 80 | 4.1 | 4.4 | 25.4 | 3.2 | 3.4 | 14.3 | 2.9 | 3.0 | 9.9 | 2.7 | 2.7 | 6.3 | 2.4 | 2.6 | 4.3 |
| 90 | 5.8 | 6.9 | 33.9 | 4.5 | 5.4 | 23.6 | 3.8 | 4.5 | 18.7 | 3.4 | 3.7 | 13.4 | 3.0 | 3.5 | 12.0 |
| Time from onset of apnoea to SaO240% (min) | |||||||||||||||
| 60 | 6.0 | 6.6 | 45.7 | 4.6 | 5.0 | 23.8 | 4.6 | 4.9 | 19.7 | 4.4 | 4.7 | 17.9 | 4.5 | 4.7 | 16.2 |
| 70 | 6.5 | 7.1 | 46.1 | 5.0 | 5.4 | 24.8 | 4.8 | 5.2 | 20.4 | 4.6 | 4.9 | 18.5 | 4.7 | 5.0 | 16.7 |
| 80 | 7.0 | 7.8 | 47.4 | 5.4 | 5.9 | 25.8 | 4.9 | 5.3 | 21.0 | 4.8 | 5.1 | 19.4 | 4.8 | 5.1 | 16.9 |
| 90 | 8.9 | 10.5 | 52.7 | 6.8 | 8.1 | 34.3 | 6.1 | 7.1 | 28.4 | 5.6 | 6.5 | 25.5 | 5.6 | 6.6 | 24.0 |