Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Ontario, Canada.
JAMA. 2010 Mar 3;303(9):865-73. doi: 10.1001/jama.2010.218.
Trials comparing higher vs lower levels of positive end-expiratory pressure (PEEP) in adults with acute lung injury or acute respiratory distress syndrome (ARDS) have been underpowered to detect small but potentially important effects on mortality or to explore subgroup differences.
To evaluate the association of higher vs lower PEEP with patient-important outcomes in adults with acute lung injury or ARDS who are receiving ventilation with low tidal volumes and to investigate whether these associations differ across prespecified subgroups.
Search of MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials (1996-January 2010) plus a hand search of conference proceedings (2004-January 2010).
Two reviewers independently screened articles to identify studies randomly assigning adults with acute lung injury or ARDS to treatment with higher vs lower PEEP (with low tidal volume ventilation) and also reporting mortality.
Data from 2299 individual patients in 3 trials were analyzed using uniform outcome definitions. Prespecified effect modifiers were tested using multivariable hierarchical regression, adjusting for important prognostic factors and clustering effects.
There were 374 hospital deaths in 1136 patients (32.9%) assigned to treatment with higher PEEP and 409 hospital deaths in 1163 patients (35.2%) assigned to lower PEEP (adjusted relative risk [RR], 0.94; 95% confidence interval [CI], 0.86-1.04; P = .25). Treatment effects varied with the presence or absence of ARDS, defined by a value of 200 mm Hg or less for the ratio of partial pressure of oxygen to fraction of inspired oxygen concentration (P = .02 for interaction). In patients with ARDS (n = 1892), there were 324 hospital deaths (34.1%) in the higher PEEP group and 368 (39.1%) in the lower PEEP group (adjusted RR, 0.90; 95% CI, 0.81-1.00; P = .049); in patients without ARDS (n = 404), there were 50 hospital deaths (27.2%) in the higher PEEP group and 44 (19.4%) in the lower PEEP group (adjusted RR, 1.37; 95% CI, 0.98-1.92; P = .07). Rates of pneumothorax and vasopressor use were similar.
Treatment with higher vs lower levels of PEEP was not associated with improved hospital survival. However, higher levels were associated with improved survival among the subgroup of patients with ARDS.
比较成人急性肺损伤或急性呼吸窘迫综合征（ARDS）患者接受更高或更低水平呼气末正压（PEEP）治疗的试验，其在检测死亡率方面的微小但潜在重要影响的能力或探索亚组差异的能力都不足。
评估与接受低潮气量通气的成人急性肺损伤或 ARDS 患者相比，更高或更低 PEEP 与患者重要结局的相关性，并研究这些相关性是否在特定的亚组中存在差异。
检索 MEDLINE、EMBASE 和 Cochrane 对照试验中心注册库（1996 年 1 月至 2010 年 1 月），并辅以会议记录的手工检索（2004 年 1 月至 2010 年 1 月）。
两名审查员独立筛选文章，以确定将成人急性肺损伤或 ARDS 患者随机分配至更高或更低 PEEP（低潮气量通气）治疗，并报告死亡率的研究。
使用统一的结局定义，分析来自 3 项试验的 2299 名患者的数据。使用多变量层次回归来测试预先设定的效应修饰因子，同时调整重要的预后因素和聚类效应。
在接受高 PEEP 治疗的 1136 名患者中有 374 例（32.9%）发生院内死亡，而在接受低 PEEP 治疗的 1163 名患者中有 409 例（35.2%）发生院内死亡（校正相对风险 [RR]，0.94；95%置信区间 [CI]，0.86-1.04；P=0.25）。治疗效果因存在或不存在 ARDS 而有所不同，ARDS 的定义为氧分压与吸入氧浓度比值（PaO2/FiO2）等于或低于 200mmHg（P=0.02 用于交互作用检验）。在 ARDS 患者（n=1892）中，高 PEEP 组有 324 例（34.1%）发生院内死亡，低 PEEP 组有 368 例（39.1%）发生院内死亡（校正 RR，0.90；95% CI，0.81-1.00；P=0.049）；在无 ARDS 患者（n=404）中，高 PEEP 组有 50 例（27.2%）发生院内死亡，低 PEEP 组有 44 例（19.4%）发生院内死亡（校正 RR，1.37；95% CI，0.98-1.92；P=0.07）。气胸和血管加压药的使用率相似。
与接受更高或更低水平的 PEEP 相比，治疗并未改善患者的院内生存率。然而，在 ARDS 亚组患者中，更高水平的 PEEP 与生存率的提高相关。
