摘要译文（供参考）
《减肥手术后的呼气末正压与苏醒前预充氧：一项关于术后氧合的随机对照试验》
背景：呼气末正压（PEEP）对于增加肺容量和抵消麻醉期间的气道闭合非常重要，尤其是在肥胖患者中。然而，在苏醒前预充氧期间维持 PEEP 可能会增加术后肺不张，因为当小气道由于拔管时 PEEP 的突然消失而塌陷时，易受影响的肺区域会被高吸收性氧气填充，这些氧气会被困住。
目的：本研究旨在检验在苏醒前预充氧之前撤除 PEEP 将更好地维持术后氧合这一假设。
设计：前瞻性随机对照试验。
设置：2019 年 12 月至 2023 年 1 月期间在瑞典的一家二级单中心医院。
患者：共 60 名患者，体重指数在 35 至 50 kg/m²之间，接受腹腔镜减肥手术。
干预措施：所有患者的术中通气相同，根据体重指数设置固定的 PEEP 为 12 或 14 cmH₂O。未使用肺复张操作。手术后，患者在苏醒前预充氧期间被分配到维持 PEEP 组或零 PEEP 组。
主要结局指标：主要结局是从苏醒前到术后 45 分钟氧合的变化，通过从动脉血气计算得出的估计静脉掺杂来测量。
结果：两组患者术后氧合均受损；在苏醒期间维持 PEEP 的组中，估计静脉掺杂平均增加 9.1%，而在苏醒期间为零 PEEP 的组中，估计静脉掺杂平均增加 10.6%，差异为-1.5%（95%置信区间-4.6 至 1.7%），P = 0.354。在整个麻醉过程中，与清醒状态相比，两组患者均表现出低驱动压和良好的氧合。
结论：在接受腹腔镜减肥手术的肥胖患者中，在苏醒前预充氧之前撤除 PEEP 并未改变术后早期氧合。尽管使用固定的 PEEP 且未进行肺复张操作，但术中氧合良好，而在拔管后恶化，这表明需要进行未来的研究以改善苏醒过程。
临床试验编号和注册处：www.clinicaltrials.gov，NCT04150276。注册日期：2019 年 11 月 4 日。主要研究者：Erland Östberg。
原文摘要
Positive end-expiratory pressure and emergence preoxygenation after bariatric surgery: A randomised controlled trial on postoperative oxygenation
Background: Positive end-expiratory pressure (PEEP) is important to increase lung volume and counteract airway closure during anaesthesia, especially in obese patients. However, maintaining PEEP during emergence preoxygenation might increase postoperative atelectasis by allowing susceptible lung areas to be filled with highly absorbable oxygen that gets entrapped when small airways collapse due to the sudden loss of PEEP at extubation.
Objective: This study aimed to test the hypothesis that withdrawing PEEP just before emergence preoxygenation would better maintain postoperative oxygenation.
Design: Prospective, randomised controlled trial.
Setting: Single centre secondary hospital in Sweden between December 2019 and January 2023.
Patients: A total of 60 patients, with body mass index between 35 and 50 kg m -2 , undergoing laparoscopic bariatric surgery.
Intervention: Intraoperative ventilation was the same for all patients with a fixed PEEP of 12 or 14 cmH 2 O depending on body mass index. No recruitment manoeuvres were used. After surgery, patients were allocated to maintained PEEP or zero PEEP during emergence preoxygenation.
Main outcome measures: The primary outcome was change in oxygenation from before awakening to 45 min postoperatively as measured by estimated venous admixture calculated from arterial blood gases.
Results: Both groups had impaired oxygenation postoperatively; in the group with PEEP maintained during awakening, estimated venous admixture increased by mean 9.1%, and for the group with zero PEEP during awakening, estimated venous admixture increased by mean 10.6%, difference -1.5% (95% confidence interval -4.6 to 1.7%), P = 0.354. Throughout anaesthesia, both groups exhibited low driving pressures and superior oxygenation compared with the awake state.
Conclusions: Withdrawing PEEP before emergence preoxygenation, did not alter early postoperative oxygenation in obese patients undergoing laparoscopic bariatric surgery. Intraoperative oxygenation was excellent despite using fixed PEEP and no recruitment manoeuvres, but deteriorated after extubation, indicating a need for future studies aimed at improving the emergence procedure.
Clinical trial number and registry: www.clinicaltrials.gov , NCT04150276. Registration date: 4 November 2019. Principal investigator: Erland Östberg.
