Positive end-expiratory pressure during one-lung ventilation for preventing atelectasis after video-assisted thoracoscopic surgery: a triple-arm, randomized controlled trial

BACKGROUND: There is little evidence regarding the benefits of lung-protective ventilation in patients undergoing one-lung ventilation for thoracic surgery. This study aimed to determine the optimal level of positive end-expiratory pressure (PEEP) during one-lung ventilation for minimizing postoperative atelectasis through lung ultrasonography. METHODS: A total of 142 adult patients scheduled for video-assisted thoracoscopic surgery at Seoul National University Hospital between May 2019 and February 2020 were enrolled in this study. Patients were randomly assigned to different groups: 1) PEEP 3 cmH(2)O group; 2) PEEP 6 cmH(2)O group; and 3) PEEP 9 cmH(2)O group during one-lung ventilation. The lung ultrasound score was used to evaluate lung aeration using ultrasonography 1 hour after surgery.RESULTS: The 1-hour post-surgery lung ultrasound scores were 8.1 +/- 2.5, 6.8 +/- 2.6, and 5.9 +/- 2.6 in the PEEP 3, 6, and 9 cmH(2)O groups, respectively (P<0.001). The PEEP 3 cmH(2)O group showed significantly higher lung ultrasound scores than the PEEP 6 (adjusted P=0.034) and 9 cmH(2)O groups (adjusted P<0.001). The PaO2/FiO(2) ratio measured at 10 minutes after the end of one-lung ventilation was significantly lower in the PEEP 3 cmH(2)O group (392 [331 to 469]) than the PEEP 6 cmH(2)O (458 [384 to 530], adjusted P=0.018) or PEEP 9 cmH(2)O groups (454 [374 to 522], adjusted P=0.016).CONCLUSIONS: Although the optimal level of PEEP during one-lung ventilation was not determined, the application of higher PEEP can prevent aeration loss in the ventilated lung after video-assisted thoracoscopic surgery under one-lung ventilation.