Department of Anesthesiology and Critical Care Medicine, Pulmonary Engineering Group, University Hospital Carl Gustav Carus, Technische Universität Dresden, Germany.
Department of Critical Care Medicine, Hospital Israelita Albert Einstein, Sao Paulo, Brazil.
JAMA. 2019 Jun 18;321(23):2292-2305. doi: 10.1001/jama.2019.7505.
An intraoperative higher level of positive end-expiratory positive pressure (PEEP) with alveolar recruitment maneuvers improves respiratory function in obese patients undergoing surgery, but the effect on clinical outcomes is uncertain.
To determine whether a higher level of PEEP with alveolar recruitment maneuvers decreases postoperative pulmonary complications in obese patients undergoing surgery compared with a lower level of PEEP.
DESIGN, SETTING, AND PARTICIPANTS: Randomized clinical trial of 2013 adults with body mass indices of 35 or greater and substantial risk for postoperative pulmonary complications who were undergoing noncardiac, nonneurological surgery under general anesthesia. The trial was conducted at 77 sites in 23 countries from July 2014-February 2018; final follow-up: May 2018.
Patients were randomized to the high level of PEEP group (n = 989), consisting of a PEEP level of 12 cm H2O with alveolar recruitment maneuvers (a stepwise increase of tidal volume and eventually PEEP) or to the low level of PEEP group (n = 987), consisting of a PEEP level of 4 cm H2O. All patients received volume-controlled ventilation with a tidal volume of 7 mL/kg of predicted body weight.
The primary outcome was a composite of pulmonary complications within the first 5 postoperative days, including respiratory failure, acute respiratory distress syndrome, bronchospasm, new pulmonary infiltrates, pulmonary infection, aspiration pneumonitis, pleural effusion, atelectasis, cardiopulmonary edema, and pneumothorax. Among the 9 prespecified secondary outcomes, 3 were intraoperative complications, including hypoxemia (oxygen desaturation with Spo2 ≤92% for >1 minute).
Among 2013 adults who were randomized, 1976 (98.2%) completed the trial (mean age, 48.8 years; 1381 [69.9%] women; 1778 [90.1%] underwent abdominal operations). In the intention-to-treat analysis, the primary outcome occurred in 211 of 989 patients (21.3%) in the high level of PEEP group compared with 233 of 987 patients (23.6%) in the low level of PEEP group (difference, -2.3% [95% CI, -5.9% to 1.4%]; risk ratio, 0.93 [95% CI, 0.83 to 1.04]; P = .23). Among the 9 prespecified secondary outcomes, 6 were not significantly different between the high and low level of PEEP groups, and 3 were significantly different, including fewer patients with hypoxemia (5.0% in the high level of PEEP group vs 13.6% in the low level of PEEP group; difference, -8.6% [95% CI, -11.1% to 6.1%]; P < .001).
Among obese patients undergoing surgery under general anesthesia, an intraoperative mechanical ventilation strategy with a higher level of PEEP and alveolar recruitment maneuvers, compared with a strategy with a lower level of PEEP, did not reduce postoperative pulmonary complications.
ClinicalTrials.gov Identifier: NCT02148692.
重要性：术中给予更高水平的呼气末正压（PEEP）并采用肺泡复张手法可改善行手术肥胖患者的呼吸功能，但对临床结局的影响尚不确定。
目的：确定与较低水平的 PEEP 相比，采用肺泡复张手法的较高 PEEP 是否可降低行手术肥胖患者的术后肺部并发症。
设计、设置和参与者：这是一项 2013 例 BMI 为 35 或更高且有发生术后肺部并发症高危风险的成年人参与的随机临床试验，这些患者在全身麻醉下接受非心脏、非神经外科手术。该试验于 2014 年 7 月至 2018 年 2 月在 23 个国家的 77 个地点进行；最终随访：2018 年 5 月。
干预措施：患者被随机分配至高水平 PEEP 组（n = 989），该组给予 12 cm H2O 的 PEEP 水平并采用肺泡复张手法（潮气量和最终 PEEP 逐渐增加）；或低水平 PEEP 组（n = 987），该组给予 4 cm H2O 的 PEEP 水平。所有患者均接受容量控制通气，潮气量为预计体重的 7 mL/kg。
主要结局和测量指标：主要结局为术后 5 天内的肺部并发症综合情况，包括呼吸衰竭、急性呼吸窘迫综合征、支气管痉挛、新的肺部浸润、肺部感染、吸入性肺炎、胸腔积液、肺不张、心肺水肿和气胸。在 9 个预先指定的次要结局中，有 3 个为术中并发症，包括低氧血症（SpO2 下降至≤92%并持续 1 分钟以上）。
结果：在随机分配的 2013 例成年人中，有 1976 例（98.2%）完成了试验（平均年龄 48.8 岁；1381 例[69.9%]为女性；1778 例[90.1%]接受了腹部手术）。意向治疗分析显示，高水平 PEEP 组有 211 例（21.3%）患者发生主要结局，低水平 PEEP 组有 233 例（23.6%）患者发生该结局（差异，-2.3%[95%CI，-5.9%至 1.4%]；风险比，0.93[95%CI，0.83 至 1.04]；P = .23）。在 9 个预先指定的次要结局中，有 6 个在高水平 PEEP 组和低水平 PEEP 组之间无显著差异，有 3 个有显著差异，包括低氧血症患者较少（高水平 PEEP 组 5.0%，低水平 PEEP 组 13.6%；差异，-8.6%[95%CI，-11.1%至 6.1%]；P < .001）。
结论和相关性：在全身麻醉下接受手术的肥胖患者中，与较低水平的 PEEP 相比，采用较高水平的 PEEP 并采用肺泡复张手法的术中机械通气策略并未降低术后肺部并发症。
试验注册：ClinicalTrials.gov 标识符：NCT02148692。
