Department of Anaesthesia and Intensive Care Medicine, University of Leipzig, Liebigstraße 20, 04103 Leipzig, Germany.
Integrated Research and Treatment Centre (IFB) AdiposityDiseases.
Br J Anaesth. 2017 Dec 1;119(6):1194-1205. doi: 10.1093/bja/aex192.
General anaesthesia leads to atelectasis, reduced end-expiratory lung volume (EELV), and diminished arterial oxygenation in obese patients. We hypothesized that a combination of a recruitment manoeuvre (RM) and individualized positive end-expiratory pressure (PEEP) can avoid these effects.
Patients with a BMI ≥35 kg m -2 undergoing elective laparoscopic surgery were randomly allocated to mechanical ventilation with a tidal volume of 8 ml kg -1 predicted body weight and (i) an RM followed by individualized PEEP titrated using electrical impedance tomography (PEEP IND ) or (ii) no RM and PEEP of 5 cm H 2 O (PEEP 5 ). Gas exchange, regional ventilation distribution, and EELV (multiple breath nitrogen washout method) were determined before, during, and after anaesthesia. The primary end point was the ratio of arterial partial pressure of oxygen to inspiratory oxygen fraction ( P aO 2 / F iO 2 ).
For PEEP IND ( n =25) and PEEP 5 ( n =25) arms together, P aO 2 / F iO 2 and EELV decreased by 15 kPa [95% confidence interval (CI) 11-20 kPa, P <0.001] and 1.2 litres (95% CI 0.9-1.6 litres, P <0.001), respectively, after intubation. Mean ( sd ) PEEP IND was 18.5 (5.6) cm H 2 O. In the PEEP IND arm, P aO 2 / F iO 2 before extubation was 23 kPa higher (95% CI 16-29 kPa; P <0.001), EELV was 1.8 litres larger (95% CI 1.5-2.2 litres; P <0.001), driving pressure was 6.7 cm H 2 O lower (95% CI 5.4-7.9 cm H 2 O; P <0.001), and regional ventilation was more equally distributed than for PEEP 5 . After extubation, however, these differences between the arms vanished.
In obese patients, an RM and higher PEEP IND restored EELV, regional ventilation distribution, and oxygenation during anaesthesia, but these differences did not persist after extubation. Therefore, lung protection strategies should include the postoperative period.
German clinical trials register DRKS00004199, www.who.int/ictrp/network/drks2/en/ .
全身麻醉会导致肥胖患者肺不张、呼气末肺容积（EELV）降低和动脉氧合减少。我们假设，采用肺复张（RM）联合个体化呼气末正压通气（PEEP）可以避免这些影响。
BMI≥35kg/m2 的择期腹腔镜手术患者被随机分配至采用 8ml/kg 预测体重的潮气量机械通气，并进行（i）RM 后采用电阻抗断层成像（EIT）滴定个体化 PEEP（PEEP IND）或（ii）无 RM 且 PEEP 为 5cmH2O（PEEP 5）。麻醉前、麻醉期间和麻醉后测定气体交换、区域通气分布和 EELV（多次呼吸氮气冲洗法）。主要终点为动脉血氧分压与吸入氧分数比值（PaO2/FiO2）。
对于 PEEP IND（n=25）和 PEEP 5（n=25）组，插管后 PaO2/FiO2 和 EELV 分别下降 15kPa（95%CI 11-20kPa，P<0.001）和 1.2L（95%CI 0.9-1.6L，P<0.001）。PEEP IND 的平均（标准差）为 18.5（5.6）cmH2O。在 PEEP IND 组，拔管前 PaO2/FiO2 高 23kPa（95%CI 16-29kPa；P<0.001），EELV 大 1.8L（95%CI 1.5-2.2L），驱动压低 6.7cmH2O（95%CI 5.4-7.9cmH2O；P<0.001），且区域通气分布更均匀。然而，拔管后两组间这些差异消失。
在肥胖患者中，RM 和较高的 PEEP IND 可在麻醉期间恢复 EELV、区域通气分布和氧合，但这些差异在拔管后并未持续。因此，肺保护策略应包括术后阶段。
德国临床试验注册中心 DRKS00004199，www.who.int/ictrp/network/drks2/en/。
