Effects of positive end-expiratory pressure/recruitment manoeuvres compared with zero end-expiratory pressure on atelectasis in children as tracked by ultrasound: A randomised clinical trial.

Background Atelectasis is a common postoperative complication. Peri-operative lung protection can reduce atelectasis; however, it is not clear whether this persists into the postoperative period. Objective To evaluate to what extent lung-protective ventilation reduces peri-operative atelectasis in children undergoing nonabdominal surgery. Design Randomised, controlled, double-blind study. Setting Single tertiary hospital, 25 July 2019 to 18 January 2020. Patients A total of 60 patients aged 1 to 6 years, American Society of Anesthesiologists physical status 1 or 2, planned for nonabdominal surgery under general anaesthesia (≤2 h) with mechanical ventilation. Interventions The patients were assigned randomly into either the lung-protective or zero end-expiratory pressure with no recruitment manoeuvres (control) group. Lung protection entailed 5 cmH2O positive end-expiratory pressure and recruitment manoeuvres every 30 min. Both groups received volume-controlled ventilation with a tidal volume of 6 ml kg-1 body weight. Lung ultrasound was conducted before anaesthesia induction, immediately after induction, surgery and tracheal extubation, and 15 min, 3 h, 12 h and 24 h after extubation. Main outcome measures The difference in lung ultrasound score between groups at each interval. A higher score indicates worse lung aeration. Results Patients in the lung-protective group exhibited lower median [IQR] ultrasound scores compared with the control group immediately after surgery, 4 [4 to 5] vs. 8 [4 to 6], (95% confidence interval for the difference between group values -4 to -4, Z = -6.324) and after extubation 3 [3 to 4] vs. 4 [4 to 4], 95% CI -1 to 0, Z = -3.161. This did not persist from 15 min after extubation onwards. Lung aeration returned to normal in both groups 3 h after extubation. Conclusions The reduced atelectasis provided by lung-protective ventilation does not persist from 15 min after extubation onwards. Further studies are needed to determine if it yields better results in other types of surgery. Trial registration Chictr.org.cn (ChiCTR2000033469).