Importance In patients who undergo mechanical ventilation during surgery, the ideal tidal volume is unclear. Objective To determine whether low-tidal-volume ventilation compared with conventional ventilation during major surgery decreases postoperative pulmonary complications. Design, Setting, and Participants Single-center, assessor-blinded, randomized clinical trial of 1236 patients older than 40 years undergoing major noncardiothoracic, nonintracranial surgery under general anesthesia lasting more than 2 hours in a tertiary hospital in Melbourne, Australia, from February 2015 to February 2019. The last date of follow-up was February 17, 2019. Interventions Patients were randomized to receive a tidal volume of 6 mL/kg predicted body weight (n = 614; low tidal volume group) or a tidal volume of 10 mL/kg predicted body weight (n = 592; conventional tidal volume group). All patients received positive end-expiratory pressure (PEEP) at 5 cm H2O. Main Outcomes and Measures The primary outcome was a composite of postoperative pulmonary complications within the first 7 postoperative days, including pneumonia, bronchospasm, atelectasis, pulmonary congestion, respiratory failure, pleural effusion, pneumothorax, or unplanned requirement for postoperative invasive or noninvasive ventilation. Secondary outcomes were postoperative pulmonary complications including development of pulmonary embolism, acute respiratory distress syndrome, systemic inflammatory response syndrome, sepsis, acute kidney injury, wound infection (superficial and deep), rate of intraoperative need for vasopressor, incidence of unplanned intensive care unit admission, rate of need for rapid response team call, intensive care unit length of stay, hospital length of stay, and in-hospital mortality. Results Among 1236 patients who were randomized, 1206 (98.9%) completed the trial (mean age, 63.5 years; 494 [40.9%] women; 681 [56.4%] undergoing abdominal surgery). The primary outcome occurred in 231 of 608 patients (38%) in the low tidal volume group compared with 232 of 590 patients (39%) in the conventional tidal volume group (difference, -1.3% [95% CI, -6.8% to 4.2%]; risk ratio, 0.97 [95% CI, 0.84-1.11]; P = .64). There were no significant differences in any of the secondary outcomes. Conclusions and Relevance Among adult patients undergoing major surgery, intraoperative ventilation with low tidal volume compared with conventional tidal volume, with PEEP applied equally between groups, did not significantly reduce pulmonary complications within the first 7 postoperative days. Trial Registration ANZCTR Identifier: ACTRN12614000790640.

中文翻译：

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术中低潮气量与常规潮气量对大手术患者术后肺部并发症的影响

重要性 在手术期间接受机械通气的患者中，理想的潮气量尚不清楚。目的 确定大手术期间低潮气量通气与常规通气相比是否能减少术后肺部并发症。设计、设置和参与者 2015 年 2 月在澳大利亚墨尔本的一家三级医院进行的 1236 名 40 岁以上的 40 岁以上患者的单中心、评估者盲法、随机临床试验，在全身麻醉下接受了持续超过 2 小时的非心胸非颅内大手术至 2019 年 2 月。随访的最后日期为 2019 年 2 月 17 日。 干预措施 患者随机接受潮气量 6 mL/kg 预测体重（n = 614；低潮气量组）或潮气量 10 mL/kg 预测体重（n = 592；常规潮气量组）。所有患者均接受 5 cm H2O 的呼气末正压 (PEEP)。主要结果和措施 主要结果是术后前 7 天内的术后肺部并发症的综合，包括肺炎、支气管痉挛、肺不张、肺充血、呼吸衰竭、胸腔积液、气胸或术后有创或无创通气的非计划需要。次要结局是术后肺部并发症，包括肺栓塞的发生、急性呼吸窘迫综合征、全身炎症反应综合征、败血症、急性肾损伤、伤口感染（浅表和深部）、术中对血管加压药的需求率、意外入住重症监护病房的发生率，快速响应团队呼叫的需求率，重症监护病房住院时间、住院时间和住院死亡率。结果 在随机分组的 1236 名患者中，1206 名 (98.9%) 完成了试验（平均年龄 63.5 岁；494 名 [40.9%] 女性；681 名 [56.4%] 接受腹部手术）。主要结果发生在低潮气量组 608 名患者中的 231 名 (38%) 与常规潮气量组 590 名患者中的 232 名 (39%)（差异，-1.3% [95% CI，-6.8% 至4.2%]；风险比，0.97 [95% CI，0.84-1.11]；P = .64）。任何次要结果均无显着差异。结论和相关性 在接受大手术的成年患者中，与常规潮气量相比，术中通气低潮气量，PEEP 在组间平均应用，在术后前 7 天内没有显着减少肺部并发症。试用注册 ANZCTR 标识符：ACTRN12614000790640。