Abstract No. : ABS1297: Evaluation of High flow humidified nasal oxygenation as a technique for preoxygenation in full term pregnant women

Abstract

Background & Aims:Obstetric airway guidelines recommend preoxygenation before the induction of general anaesthesia to achieve an end tidal oxygen concentration of > 90% .We evaluated the use of high flow humidified nasal oxygenation (HFNO) as a technique for preoxygenation in full term pregnant women.Methods:A cross sectional observational study was conducted in 100 term pregnant women. They underwent preoxygenation using HFNO for 4 minutes (30l/min for 30 seconds 50l/min for 210 secs) and end tidal oxygen concentration was measured at the end of preoxygenation. The primary outcome was the percentage of women who achieved an expired oxygen concentration of >90% for the first expired breath. The secondary outcome was the acceptability and comfort for the HFNO as compared to facemask preoxygenation using 4-point Likert scale. A cross sectional observational study was conducted in 100 term pregnant women. They underwent preoxygenation using HFNO.Results:The percentage of women who achieved expired oxygen concentration of >90% after 4 minutes of HFNO preoxygenation was 32% [ 95% confidence interval (CI):22.7-41.3%] with the mean end tidal oxygen(SD) being 86.67(3.4). 71% [mean (SD): 2.94(0.92)] found nasal cannula and 56% [mean (SD): 2.67(1.21)] found facemask comfortable and acceptable for preoxygenation (P value, 0.05).Conclusion:HFNO is a comfortable technique, but when used for 4minutes preoxygenation, it does not achieve an acceptable level (ETO2 >90% in 95% of individuals). Therefore, it is an inadequate technique for preoxygenation in term pregnant women.TableExpired oxygen concentration(ET02) after 4 minutes of HFNO.VariableMean±SDMedian (25th-75th percentile)95% CI for meanRangeExpired oxygen concentration86.67±3.487 (84-90)85.996-87.34478-91