摘要目的:腹腔镜结直肠癌手术全身麻醉机械通气后，约90%的患者会出现不同程度的肺不张。本研究拟验证，在腹腔镜手术中小潮气量机械通气期间，应用间歇肺复张手法（RM）联合中等水平呼气末正压（PEEP）构成的肺开放策略（OLS）可减少肺不张，从而减少术中氧合障碍的发生这一推测，为腹腔镜结直肠癌手术提供更优的术中机械通气方案。方法:本研究采用前瞻性随机对照研究方法，研究方案经中山大学附属第六医院伦理委员会的批准（审批号：2017ZSLYEC-002），并在ClinicalTrials.gov上进行注册（注册号：NCT03160144）。研究纳入2017年1—7月间，接受结直肠癌腹腔镜手术、年龄>40岁、预计气腹时间≥1.5 h、脉搏氧饱和度（SpO 2）≥92%以及术后肺部并发症风险分级≥2级的患者，排除美国麻醉医师协会分级≥Ⅳ级、近1个月内有肺炎、急性呼吸衰竭或脓毒血症史、体质指数≥30 kg/m 2、有严重慢性阻塞性肺疾病、肺大泡和进行性神经肌肉疾病以及参与了其他干预性临床研究的患者。随机（1∶1）分入OLS组（机械通气期间PEEP设为8 cmH 2O并间歇给予RM）或NOLS组（机械通气期间不给予OLS）。气腹后0.5 h（T 1）、1.5 h（T 2）及入复苏室后20 min分别行动脉、中心静脉血气分析，计算动脉血氧分压/吸入氧浓度（PaO 2/FiO 2）和分流率（Q S/Q T），并根据监护数据计算气腹前即刻（T 0）和T 2时的呼吸驱动压。主要结局事件是术中机械通气期间发生的氧合障碍（PaO 2/FiO 2≤300 mmHg）。 结果:96例在全身麻醉小潮气量机械通气下行手术的患者被纳入分析（每组48例）。机械通气时，氧合障碍累计发生率OLS组14.6%（7/48），NOLS组35.4%（17/48），两组比较差异有统计学意义（χ 2=5.556，RR=0.31，95% CI：0.12~0.84， P=0.033）。机械通气期间，OLS组PaO 2/FiO 2高于NOLS组[T 1时，（427±103） mmHg比（366±109） mmHg， t=-2.826， P=0.006；T 2时，（453±103） mmHg比（388±122）mmHg， t=-2.739， P=0.007]；OLS组呼吸驱动压[T 0时，（6±3）cmH 2O比（10±2） cmH 2O， t=7.421， P<0.001；T 2时，（13±3） cmH 2O比（17±4） cmH 2O， t=5.417， P<0.001]和Q S/Q T低于NOLS组[T 1时，（9.2±6.5）%比（12.6±7.7）%， t=2.322， P=0.022；T 2时，（7.0±5.8）%比（10.9±9.2）%， t=2.408， P=0.019]；差异均有统计学意义。在复苏室，虽然OLS组比NOLS组PaO 2较高，Q S/Q T较低，但差异无统计学意义（均 P>0.05）。 结论:腹腔镜结直肠癌手术麻醉小潮气量机械通气期间，应用这种OLS可减少术中氧合障碍的发生率，并可能持续至术后麻醉苏醒期。

abstractsObjective:After general anesthesia and mechanical ventilation for laparoscopic colorectal cancer resection, about 90% of patients would have different degrees of atelectasis. Authors speculated that an open-lung strategy (OLS) comprising moderate positive end-expiratory pressure (PEEP) and intermittent recruitment maneuvers (RM) can reduce atelectrauma and thus reduce the incidence of oxygenation-impairment during low-tidal-volume ventilation for laparoscopic colorectal cancer resection. The purpose of this study was to verify this hypothesis and provide a better intraoperative ventilation scheme for laparoscopic colorectal cancer resection.Methods:This was a prospectively randomized controlled clinical trial which was approved by the Ethics Committee of the Sixth Affiliated Hospital, Sun Yat-sen University (2017ZSLYEC-002), and registered at the ClinicalTrials.gov (NCT03160144). From January to July 2017, patients who underwent laparoscopic colorectal cancer resection, with age > 40 years, estimated pneumoperitoneum time ≥ 1.5 h, pulse oxygen saturation ≥ 92%, and risk grade for postoperative pulmonary complications ≥ 2 were prospectively enrolled. The patients with American Society of Anesthesiologists physical status ≥ IV, body mass index ≥ 30 kg/m 2, pneumonia, acute respiratory failure or sepsis within 1 month, severe chronic obstructive pulmonary disease, pulmonary bullae and progressive neuromuscular diseases, and those participating in other interventional clinical trials were excluded. The enrolled patients were randomly assigned (1:1) to the OLS group (with a PEEP of 6-8 cm H 2O and intermittent RM), and the NOLS group (without using PEEP and RM). Partial pressure of arterial oxygen (PaO 2) /fraction of inspired oxygen (FiO 2) and shunt fraction (Q S/Q T) were calculated via arterial and central venous blood gas analysis performed at 0.5 h (T 1), 1.5 h (T 2) after pneumoperitoneum induction and at 20 min after admission to the recovery room. Driving pressure immediately before pneumoperitoneum induction (T 0) and at T 2 were calculated via monitoring data. The primary outcome was oxygenation-impairment (PaO 2/FiO 2 ≤ 300 mmHg) during mechanical ventilation. Results:In each group, 48 patients under general anesthesia and low-tidal-volume ventilation were included in the final analysis. During ventilation, the oxygenation-impairment occurred in 7 patients (14.6%) of OLS group and in 17 patients (35.4%) of NOLS group, whose difference was statistically significant between two groups (χ 2=5.556, RR=0.31, 95%CI: 0.12 to 0.84, P=0.033). During ventilation, the patients in the OLS group had higher PaO 2/FiO 2 [T 1: (427±103) mmHg vs. (366±109) mmHg, t=-2.826, P=0.006; T 2: (453±103) mmHg vs. (388±122) mmHg, t=-2.739, P=0.007], lower Q S/Q T [ T 1: (9.2±6.5) % vs. (12.6±7.7) %, t=2.322, P=0.022; T 2: (7.0±5.8)% vs.(10.9±9.2)%, t=2.408, P=0.019], and lower driving pressure [T 0: (6±3) cm H 2O vs. (10±2) cm H 2O, t=7.421, P<0.001; T 2: (13±3) cm H 2O vs. (17±4) cm H 2O, t=5.417, P<0.001] than those in the NOLS group, with stratistical differences in all comparisons. In recovery room, though PaO 2/FiO 2 [(70.3±9.4) mmHg vs. (66.8±9.4) mmHg, P=0.082] was still higher and Q S/Q T [(18.6±8.3)% vs. (21.8±8.4)%, P=0.070] was still lower in the OLS group as compared to the NOLS group, the differences were not statistically significant (both P>0.05). Conclusion:The application of such an OLS during low-tidal-volume ventilation can greatly reduce the incidence of oxygenation-impairment in laparoscopic colorectal cancer resection, and such effect may last to the period of emergence from anesthesia.