Effect of high-flow nasal preoxygenation on anesthetic preparation time for general anesthesia in emergency caesarean...

General anesthesia may be required for emergency caesarean deliveries when neuraxial anesthesia is not feasible. Anesthetic preparation, including adequate facemask preoxygenation, may take longer in the absence of a trained assistant, potentially prolonging the decision-to-delivery interval. High-flow nasal oxygenation (HFNO) offers hands-free preoxygenation, but its impact on anesthetic preparation time has not been assessed.

We conducted a prospective, randomised, single-centre, cross-over simulation study with eight obstetric anesthetists, each performing four predefined preoxygenation scenarios on the same healthy female volunteer in whom abdominal compression was applied to produce 20% reduction in functional residual capacity: standard facemask preoxygenation by a single anesthetist (Control), facemask preoxygenation with the mask held by the volunteer (Patient-Assisted) or assisted by a nurse anesthetist (nurse-assisted), HFNO preoxygenation by a single anesthetist (HFNO). The primary endpoint was time from entry-to-operating room to readiness-for-induction.

All 32 simulations were completed. The median (IQR) times from the volunteer's entry in the operating room to readiness for anesthesia induction were 4.14 (3.96-4.80) minutes (Control), 3.16 (3.03-3.38) minutes (HFNO), 2.61 (2.45-2.81) minutes (Patient-Assisted), and 2.29 (2.25-3.09) minutes (Nurse-Assisted). A generalized linear mixed model found significant difference between the Control and the HFNO scenario (mean difference: -1.12 minutes, 95% CI: -2.04 to -0.18); the Patient-Assisted scenario (mean difference: -1.73 minutes, 95% CI: -2.61 to -0.86); and the Nurse-Assisted scenario (mean difference: -1.81 minutes, 95% CI: -2.71 to -0.91).

HFNO preoxygenation was associated with reduced anesthetic preparation time compared with facemask preoxygenation in simulated emergency obstetric anesthesia managed by a single anesthetist without assistance.