Imberger Georgina, McIlroy David, Pace Nathan Leon, Wetterslev Jørn, Brok Jesper, Møller Ann Merete
The Cochrane Anaesthesia Review Group, Rigshospitalet, Blegdamsvej 9,, Afsnit 3342, København, Denmark, 2100.
Cochrane Database Syst Rev. 2010 Sep 8(9):CD007922. doi: 10.1002/14651858.CD007922.pub2.
General anaesthesia causes atelectasis which can lead to impaired respiratory function. Positive end-expiratory pressure (PEEP) is a mechanical manoeuvre which increases functional residual capacity (FRC) and prevents collapse of the airways thereby reducing atelectasis. It is not known whether intra-operative PEEP alters the risk of postoperative mortality and pulmonary complications.
To assess the benefits and harms of intraoperative PEEP, for all adult surgical patients, on postoperative mortality and pulmonary outcomes.
We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2009, Issue 4), MEDLINE (via Ovid) (1966 to January 2010), EMBASE (via Ovid) (1980 to January 2010), CINAHL (via EBSCOhost) (1982 to January 2010), ISI Web of Science (1945 to January 2010) and LILACS (via BIREME interface) (1982 to January 2010).
We included randomized clinical trials that evaluated the effect of PEEP versus no PEEP, during general anaesthesia, on postoperative mortality and postoperative respiratory complications. We included studies irrespective of language and publication status.
Two investigators independently selected papers, extracted data that fulfilled our outcome criteria and assessed the quality of all included trials. We undertook pooled analyses, where appropriate. For our primary outcome (mortality) and two secondary outcomes (respiratory failure and pneumonia), we calculated the number of further patients needed (information size) in order to make reliable conclusions.
We included eight randomized trials with a total of 330 patients. Two trials had a low risk of bias. There was no difference demonstrated for mortality (relative risk (RR) 0.95, 95% CI 0.14 to 6.39). Two statistically significant results were found: the PEEP group had a higher PaO(2)/FiO(2) on day 1 postoperatively (mean difference (MD) 22.98, 95% CI 4.40 to 41.55) and postoperative atelectasis (defined as an area of collapsed lung, quantified by computerized tomography (CT) scan) was less in the PEEP group (SMD -1.2, 95% CI -1.78 to -0.79). There were no adverse events reported in the three trials that adequately measured these outcomes (barotrauma and cardiac complications). Using information size calculations, we estimated that a further 21,200 patients would need to be randomized in order to make a reliable conclusion about PEEP and mortality.
AUTHORS' CONCLUSIONS: There is currently insufficient evidence to make conclusions about whether intraoperative PEEP alters the risk of postoperative mortality and respiratory complications among undifferentiated surgical patients.
全身麻醉会导致肺不张，进而可能损害呼吸功能。呼气末正压通气（PEEP）是一种机械操作，可增加功能残气量（FRC）并防止气道塌陷，从而减少肺不张。目前尚不清楚术中使用PEEP是否会改变术后死亡率和肺部并发症的风险。
评估术中PEEP对所有成年外科手术患者术后死亡率和肺部结局的利弊。
我们检索了Cochrane对照试验中心注册库（CENTRAL）（《Cochrane图书馆》2009年第4期）、MEDLINE（通过Ovid）（1966年至2010年1月）、EMBASE（通过Ovid）（1980年至2010年1月）、CINAHL（通过EBSCOhost）（1982年至2010年1月）、科学引文索引（ISI）数据库（1945年至2010年1月）以及拉丁美洲和加勒比卫生科学数据库（LILACS）（通过BIREME界面）（1982年至2010年1月）。
我们纳入了评估全身麻醉期间PEEP与不使用PEEP对术后死亡率和术后呼吸并发症影响的随机临床试验。我们纳入的研究不受语言和发表状态的限制。
两名研究人员独立筛选论文，提取符合我们结局标准的数据，并评估所有纳入试验的质量。在适当情况下，我们进行了汇总分析。对于我们的主要结局（死亡率）和两个次要结局（呼吸衰竭和肺炎），我们计算了为得出可靠结论所需的更多患者数量（信息规模）。
我们纳入了八项随机试验，共计330例患者。两项试验的偏倚风险较低。未发现死亡率有差异（相对危险度（RR）0.95，95%可信区间0.14至6.39）。发现了两个具有统计学意义的结果：PEEP组术后第1天的PaO₂/FiO₂较高（平均差（MD）22.98，95%可信区间4.40至41.55），且PEEP组术后肺不张（定义为肺萎陷区域，通过计算机断层扫描（CT）扫描量化）较少（标准化均数差-1.2，95%可信区间-1.78至-0.79）。在充分测量这些结局（气压伤和心脏并发症）的三项试验中，未报告不良事件。通过信息规模计算，我们估计还需要21200例患者进行随机分组，以便就PEEP与死亡率得出可靠结论。
目前尚无足够证据就术中PEEP是否会改变未分化外科手术患者术后死亡率和呼吸并发症的风险得出结论。
