Effect of individualized PEEP titrated by EIT on postoperative atelectasis in children undergoing laparoscopy: A randomized controlled trial.

Atelectasis is common during perioperative period in children. Although positive end positive end-expiratory pressure (PEEP) has been identified as a lung protective ventilation strategy to alleviate atelectasis, there's still no consensus on the optimal value of PEEP. We hypothesized that individualized PEEP titrated by electrical impedance tomography (EIT) may reduce the incidence of postoperative atelectasis. A total of 50 children aged between 2 to 7, undergoing laparoscopic hernia repair, were randomly divided into two groups according to the principle of randomization: a control group (PEEP5) and an experimental group (EIT). In the control group, PEEP was set to a fixed value of 5mmHg during pneumoperitoneum mechanical ventilation. The EIT group received an individualized PEEP determined by a decremental PEEP titration using EIT. Ultrasonic assessment and score of atelectasis were carried out post-intubation, post-surgery, and one hour post-extubation. For this study, a total of 12 lung regions were evaluated by Lung ultrasonography, and significant atelectasis was defined by a consolidation score of at least 2 in any region. The primary outcome was the incidence of atelectasis at post-surgery. The incidence of atelectasis after surgery was 92% in the control groups (n=25) and 64% in the EIT groups (n=25), respectively (odds ratio [OR], 0.72; 95% confidence interval [CI], 0.094 to 4.827; P = 0.037). The incidence of atelectasis after 1h post-extubation was 80% in the control groups (n=20) and 48% in the EIT groups (n=12), respectively (odds ratio [OR], 0.59; 95% confidence interval [CI], 0.149 to 2.215; P = 0.038). Both lung consolidations and B-lines score were significantly higher in control group than in the EIT group after surgery (consolidations: 9 vs. 7, P = 0.027; B-lines: 11 vs. 8, P = 0.002) and 1h post-extubation (consolidations: 7 vs. 4, P = 0.018; B-lines: 7 vs. 5, P = 0.037). Lung compliance using optimal PEEP during mechanical ventilation was 20.0±3.3 ml/cm HO. The desaturation (pulse oximeter value is below 95%) after extubation was observed in 7 in the control group and 1 in the EIT group (P = 0.048). Hemodynamics were stable during titration. EIT-directed individualized PEEP titration can reduce the incidence and severity of postoperative atelectasis in children undergoing laparoscopic surgery.