Relationship between the interval since high flow oxygen was received and prevalence of acidosis and hypoxia in the admission arterial blood gas
| % with pH<7.35 on admission | % with PaO2≤8.0 on admission | |
| % (N) | % (N) | |
| Proportion of cases with: | ||
| High flow oxygen not received before arterial gases taken | 14 (403/2942) | 38 (1143/2983) |
| Time interval between high flow oxygen stopped and blood gases taken: | ||
| >60 min before gases | 20 (107/537) | 39 (211/538) |
| >15 but ≤60 min before gases | 36 (127/350) | 34 (120/352) |
| ≤15 min before gases | 52 (44/85) | 33 (28/85) |
| χ2 p value (comparing above three groups) | p<0.001 | p=0.22 |
| Still receiving high flow oxygen when gases taken | 52 (244/471) | 11 (53/479) |