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Introduction

High-flow nasal oxygenation has been shown to improve oxygenation during induction of anaesthesia in parturients who are not obese. However, data on the efficacy of high-flow nasal oxygen inparturients living with obesity are lacking. This study investigated the effects of high-flow nasal oxygenation on pre-oxygenation and apnoea oxygenation during tracheal intubation in parturients living with obesity.

引言

高流量鼻导管氧疗已被证明可以在非肥胖产妇麻醉诱导期间改善氧合。然而，关于肥胖产妇使用高流量鼻导管氧疗效果的数据尚不充分。本研究调查了高流量鼻导管氧疗在肥胖产妇气管插管期间对预氧合和呼吸暂停氧合的影响。

Methods

This prospective, randomised clinical trial was conducted at two tertiary hospitals and included parturients with BMI > 30 kg.m-2 undergoing scheduled caesarean delivery under general anaesthesia.Parturients were allocated randomly to standard facemask or high-flow nasal oxygen groups (oxygen flow rates 10 l.min-1 and 50 l.min-1, respectively). The primary outcome measure was arterial partial pressure of oxygen after 3 min of pre-oxygenation.

方法

这项前瞻性、随机化的临床试验在两家三级医院进行，纳入了计划在全身麻醉下进行剖宫产的肥胖产妇（BMI > 30 kg.m-2）。产妇被随机分配到标准面罩或高流量鼻氧组（氧气流量分别为10 l.min-1和50 l.min-1）。主要结果测量指标是在预充氧3分钟后动脉氧分压。

Results

54 patients completed the study. The arterial partial pressure of oxygen after 3 min of pre-oxygenation was significantly lower in parturients allocated to the standard facemask group compared with those allocated to the high-flow nasal oxygen group (mean (SD) 40.1 (8.9) kPa vs. 53.8 (9.7) kPa, p < 0.001). End-tidal oxygen concentration on commencing ventilation was also lower in parturients allocated to the standard facemask group compared with those allocated to the high flow-nasal oxygen group (mean (SD) 78.3 (5.38)% vs. 86.2 (5.10)%, p < 0.001). The arterial partial pressure of carbon dioxide post tracheal intubation and fetal outcomes were similar in both groups.

结果

共有54名患者完成了研究。在进行3分钟预充氧后，分配到标准面罩组的产妇的动脉氧分压显著低于分配到高流量鼻氧组的产妇（平均值（标准差）40.1（8.9）kPa vs. 53.8（9.7）kPa，p < 0.001）。开始通气时，分配到标准面罩组的产妇的呼气末氧浓度也低于分配到高流量鼻氧组的产妇（平均值（标准差）78.3（5.38）% vs. 86.2（5.10）%，p < 0.001）。两组在气管插管后的动脉二氧化碳分压和胎儿结果相似。

Discussion 

Pre-oxygenation using high-flow nasal oxygenation provided a higher arterial partial pressure of oxygen and end-tidal oxygen concentration during general anaesthesia induction than standard facemask oxygenation in parturients living with obesity; however, the differences were not clinically meaningful. High-flow nasal oxygenation may be considered as an alternative option for pre-oxygenation during rapid sequence induction in parturients living with obesity.

讨论 

使用高流量鼻导管氧疗在全身麻醉诱导期间为肥胖产妇提供比标准面罩氧疗更高的动脉氧分压和呼气末氧浓度；然而，这些差异在临床上没有意义。高流量鼻导管氧疗可以被视为肥胖产妇快速序列诱导期间预充氧的另一种选择。

After 3 min of pre-oxygenation, the PaO2 of paturients allocated to the standard facemask group was significantly lower than those allocated to the HFNO group (mean (SD) 53.8 (9.7) kPa vs. 40.1 (8.9) kPa, p < 0.001).

The ETO2 on commencing ventilation was significantly lower in parturients allocated to the standard facemask group compared with those allocated to the HFNO group (mean (SD) 78.3 (5.38) kPa vs. 86.5 (5.10) kPa, p < 0.001) (Table 2, Fig. 2). There was no differencein PaCO2 or pH at the same time-point between the two groups (Table 2). The median (IQR [range]) SpO2 was

significantly lower in parturients allocated to the standard facemask group compared with those allocated to the HFNO group (98 (97–100 [85–100])% vs. 100 (100–100 [96–100])%, p = 0.001) (Table 2). The lowest recorded SpO2 after trachal intubation was also lower in parturients

allocated to the standard facemask group (Fig. 3). There was no difference in the apnoea time, skin incisionto-delivery interval or uterine incision-to-delivery interval between the two groups (Table 3). No respiratory complications (including complications related to hyperoxia) were observed in any parturient. There was no significant difference in the neonatal outcomes between the two groups (Table 4).

经过3分钟的预充氧后，分配到标准面罩组的患者的PaO2显著低于分配到高流量鼻导管氧疗（HFNO）组的患者（平均值（标准差）53.8（9.7）kPa vs. 40.1（8.9）kPa，p < 0.001）。

开始通气时，分配到标准面罩组的产妇的ETO2显著低于分配到HFNO组的产妇（平均值（标准差）78.3（5.38）kPa vs. 86.5（5.10）kPa，p < 0.001）（表2，图2）。在相同时间点，两组之间的PaCO2或pH值没有差异（表2）。分配到标准面罩组的产妇的中位数（四分位数间距[范围]）SpO2显著低于分配到HFNO组的产妇（98（97-100 [85-100]）% vs. 100（100-100 [96-100]）%，p = 0.001）（表2）。气管插管后记录的最低SpO2在分配到标准面罩组的产妇中也较低（图3）。两组之间在呼吸暂停时间、皮肤切开至分娩间隔或子宫切开至分娩间隔方面没有差异（表3）。在任何产妇中均未观察到包括与高氧血症相关的呼吸并发症。两组新生儿的结局没有显著差异（表4）。