Determining the effective pre‐oxygenation interval in obstetric patients using high‐flow nasal oxygen and standard flow rate facemask: a biased‐coin up–down sequential allocation trial

Using biased-coin sequential allocation, we sought to determine the effective time interval in 90% of healthy parturients to achieve a target endpoint end-tidal oxygen of ≥ 90% using standard flow rate facemask and high-flow nasal oxygen. Eighty healthy parturients were randomly assigned to standard facemask (n = 40) or high-flow nasal oxygen (n = 40) groups; half of the parturients in the high-flow nasal oxygen group also used a simple no-flow...