Department of Critical Care, The University of Melbourne, Parkville, Victoria 3052, Australia; The Royal Women's Hospital, 20 Flemington Road, Parkville 3052, Australia.
Department of Critical Care, The University of Melbourne, Parkville, Victoria 3052, Australia; Austin Health, 145 Studley Rd, Heidelberg, Victoria 3084, Australia.
Int J Obstet Anesth. 2024 Nov;60:104236. doi: 10.1016/j.ijoa.2024.104236. Epub 2024 Jul 23.
Airway guidelines recommend pre-oxygenation of obstetric patients to an end tidal oxygen concentration (etO) ≥90%. High flow nasal oxygen (HFNO) achieves this in 60% of pregnant people. However face mask (FM) pre-oxygenation also may not achieve this target in all patients. In this study we determined whether HFNO pre-oxygenation is non-inferior to FM pre-oxygenation.
This randomised controlled crossover non-inferiority trial was conducted on healthy participants of gestational age ≥37 weeks in a simulated environment. Participants underwent pre-oxygenation for three minutes with HFNO and FM oxygen in randomised order. HFNO was delivered at a maximal flow of 70 l.min and FM oxygen at 10 l.min. The primary outcome was etO on first expired breath after pre-oxygenation. Non-inferiority was defined as a mean difference in first etO between groups of ≤5%.
Seventy participants were randomised with 62 analysed. Age (mean (SD)), gestation (median (IQR)), and body mass index (median (IQR)), were 34.7 (4.6) years, 39 (38.4, 39.4) weeks, 29 (26.6, 32.4) kg.m respectively. First etO after HFNO pre-oxygenation was greater than after FM pre-oxygenation (HFNO pre-oxygenation mean (SD) 90.2 (3.9)% versus FM pre-oxygenation 88.7 (3.0)%; mean difference = 1.45%, 95% CI 0.19 to 2.72%; p = 0.025. Forty-four (71%) participants achieved ≥90% first etO concentration after HFNO pre-oxygenation versus 27 (44%) after FM pre-oxygenation (p = 0.002).
In this cohort of pregnant people at term in a simulated environment, pre-oxygenation with HFNO was not inferior to FM pre-oxygenation. FM pre-oxygenation did not achieve pre-oxygenation targets in over 50% of participants.
气道指南建议对产科患者进行预充氧，使潮气末氧浓度（etO）≥90%。高流量鼻氧（HFNO）可使 60%的孕妇达到这一目标。然而，面罩（FM）预充氧在所有患者中也可能无法达到这一目标。在这项研究中，我们确定了 HFNO 预充氧是否不如 FM 预充氧。
这是一项在模拟环境中进行的健康足月妊娠参与者的随机对照交叉非劣效性试验。参与者随机接受 HFNO 和 FM 氧预充氧 3 分钟。HFNO 以最大流量 70 l.min 输送，FM 氧以 10 l.min 输送。主要结局为预充氧后第一次呼气末 etO。非劣效性定义为两组之间的第一 etO 平均差异≤5%。
70 名参与者被随机分组，其中 62 名进行了分析。年龄（平均值（标准差））、孕龄（中位数（IQR））和体重指数（中位数（IQR））分别为 34.7（4.6）岁、39（38.4，39.4）周、29（26.6，32.4）kg.m。HFNO 预充氧后的第一 etO 大于 FM 预充氧后的第一 etO（HFNO 预充氧平均（SD）90.2（3.9）%与 FM 预充氧 88.7（3.0）%；平均差值=1.45%，95%置信区间 0.19 至 2.72%；p=0.025）。44（71%）名参与者在 HFNO 预充氧后达到≥90%的第一 etO 浓度，而在 FM 预充氧后达到这一浓度的参与者为 27（44%）（p=0.002）。
在这项模拟环境中足月妊娠的孕妇队列中，HFNO 预充氧并不劣于 FM 预充氧。FM 预充氧在超过 50%的参与者中无法达到预充氧目标。
