Lancet. 2014 Aug 9;384(9942):495-503. doi: 10.1016/S0140-6736(14)60416-5. Epub 2014 Jun 2.
The role of positive end-expiratory pressure in mechanical ventilation during general anaesthesia for surgery remains uncertain. Levels of pressure higher than 0 cm H2O might protect against postoperative pulmonary complications but could also cause intraoperative circulatory depression and lung injury from overdistension. We tested the hypothesis that a high level of positive end-expiratory pressure with recruitment manoeuvres protects against postoperative pulmonary complications in patients at risk of complications who are receiving mechanical ventilation with low tidal volumes during general anaesthesia for open abdominal surgery.
In this randomised controlled trial at 30 centres in Europe and North and South America, we recruited 900 patients at risk for postoperative pulmonary complications who were planned for open abdominal surgery under general anaesthesia and ventilation at tidal volumes of 8 mL/kg. We randomly allocated patients to either a high level of positive end-expiratory pressure (12 cm H2O) with recruitment manoeuvres (higher PEEP group) or a low level of pressure (≤2 cm H2O) without recruitment manoeuvres (lower PEEP group). We used a centralised computer-generated randomisation system. Patients and outcome assessors were masked to the intervention. Primary endpoint was a composite of postoperative pulmonary complications by postoperative day 5. Analysis was by intention-to-treat. The study is registered at Controlled-Trials.com, number ISRCTN70332574.
From February, 2011, to January, 2013, 447 patients were randomly allocated to the higher PEEP group and 453 to the lower PEEP group. Six patients were excluded from the analysis, four because they withdrew consent and two for violation of inclusion criteria. Median levels of positive end-expiratory pressure were 12 cm H2O (IQR 12-12) in the higher PEEP group and 2 cm H2O (0-2) in the lower PEEP group. Postoperative pulmonary complications were reported in 174 (40%) of 445 patients in the higher PEEP group versus 172 (39%) of 449 patients in the lower PEEP group (relative risk 1·01; 95% CI 0·86-1·20; p=0·86). Compared with patients in the lower PEEP group, those in the higher PEEP group developed intraoperative hypotension and needed more vasoactive drugs.
A strategy with a high level of positive end-expiratory pressure and recruitment manoeuvres during open abdominal surgery does not protect against postoperative pulmonary complications. An intraoperative protective ventilation strategy should include a low tidal volume and low positive end-expiratory pressure, without recruitment manoeuvres.
Academic Medical Center (Amsterdam, Netherlands), European Society of Anaesthesiology.
机械通气在全身麻醉下用于手术时，呼气末正压（positive end-expiratory pressure，PEEP）的作用仍不确定。高于 0 厘米水柱的压力水平可能有助于预防术后肺部并发症，但也可能导致术中循环抑制和过度膨胀引起的肺损伤。我们假设，在接受全身麻醉下机械通气且潮气量较低的开放性腹部手术患者中，使用高水平 PEEP 加复张手法可以预防术后肺部并发症。
在欧洲、北美和南美 30 个中心进行的这项随机对照试验中，我们招募了 900 名有术后肺部并发症风险的患者，这些患者计划接受全身麻醉下的开放性腹部手术，潮气量为 8ml/kg。我们将患者随机分配到高水平 PEEP（12cmH2O）加复张手法（高 PEEP 组）或低水平 PEEP（≤2cmH2O）无复张手法（低 PEEP 组）。我们使用中央计算机生成的随机化系统进行随机分组。患者和结局评估者对干预措施均不知情。主要终点是术后第 5 天的术后肺部并发症综合指标。分析采用意向治疗。该研究在 Controlled-Trials.com 注册，编号为 ISRCTN70332574。
从 2011 年 2 月至 2013 年 1 月，447 名患者被随机分配到高 PEEP 组，453 名患者被随机分配到低 PEEP 组。有 6 名患者被排除在分析之外，其中 4 名因撤回同意，2 名因违反纳入标准。高 PEEP 组的中位 PEEP 水平为 12cmH2O（12-12），低 PEEP 组为 2cmH2O（0-2）。高 PEEP 组有 174 名（40%）患者发生术后肺部并发症，低 PEEP 组有 172 名（39%）患者发生术后肺部并发症（相对风险 1.01；95%CI 0.86-1.20；p=0.86）。与低 PEEP 组相比，高 PEEP 组术中发生低血压，需要更多血管活性药物。
在开放性腹部手术中，使用高水平 PEEP 加复张手法并不能预防术后肺部并发症。术中保护性通气策略应包括低潮气量和低 PEEP，无需复张手法。
阿姆斯特丹学术医学中心（荷兰），欧洲麻醉学会。
