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<inf>2</inf>O group; 2) PEEP 6 cmH<inf>2</inf>O group; and 3) PEEP 9 cmH<inf>2</inf>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<inf>2</inf>O groups, respectively (P<0.001). The PEEP 3 cmH<inf>2</inf>O group showed significantly higher lung ultrasound scores than the PEEP 6 (adjusted P=0.034) and 9 cmH<inf>2</inf>O groups (adjusted P<0.001). The PaO<inf>2</inf>/FiO<inf>2</inf> ratio measured at 10 minutes after the end of one-lung ventilation was significantly lower in the PEEP 3 cmH<inf>2</inf>O group (392 [331 to 469]) than the PEEP 6 cmH<inf>2</inf>O (458 [384 to 530], adjusted P=0.018) or PEEP 9 cmH<inf>2</inf>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.