The efficacy of high flow nasal oxygenation for maintaining maternal oxygenation during rapid sequence induction in pregnancy: A prospective randomised clinical trial.

BACKGROUND: High-flow nasal oxygenation (HFNO) for pre-oxygenation in rapid sequence induction (RSI) has only been assessed in volunteer parturients without intubation. OBJECTIVES: To evaluate the efficacy of HFNO in comparison with the conventional facemask for oxygenation during RSI for caesarean section under general anaesthesia. SETTING: Operating room in a tertiary hospital. DESIGN: Prospective randomised, controlled study. PARTICIPANTS: Thirty-four healthy parturients undergoing general anaesthesia for caesarean section. INTERVENTIONS: Parturients were randomly assigned to HFNO or standard facemask (SFM) group. MAIN OUTCOME MEASURES: The primary outcome measure was the PaO2 immediately after intubation. Secondary outcomes included lowest saturation throughout the intubation procedure, end-tidal oxygen concentration (EtO2) on commencing ventilation, blood gas analysis (pH, PaCO2), fetal outcomes and intubation-related adverse events. RESULTS: PaO2 in the HFNO group was significantly higher than that in SFM group (441.41 ±â€Š46.73 mmHg versus 328.71 ±â€Š72.80 mmHg, P < 0.0001). The EtO2 concentration in the HFNO group was higher than that in the SFM group (86.71 ±â€Š4.12% versus 76.94 ±â€Š7.74%, P < 0.0001). Compared to baseline, PaCO2 immediately after intubation also increased significantly in both groups (HFNO group: 30.87 ±â€Š2.50 mmHg versus 38.28 ±â€Š3.18 mmHg; SFM group: 29.82 ±â€Š2.57 mmHg versus 38.05 ±â€Š5.76 mmHg, P < 0.0001), but there was no difference in PaCO2 between the two groups. There was no difference in lowest saturation, intubation times, duration of apnoea, pH value or fetal outcomes. CONCLUSIONS: Compared with SFM, HFNO provided a higher PaO2 and EtO2 immediately after intubation in parturients. HFNO is safe as a method of oxygenation during RSI in parturients undergoing general anaesthesia for caesarean section. TRIAL REGISTRATION: Clinical trial ChiCTR1900023121.