Volume-controlled ventilation versus pressure-controlled ventilation with volume guarantee in emergency surgery: A randomized controlled trial.

Abstract

Emergency laparotomy is associated with a high risk of postoperative pulmonary complications. Pressure-controlled ventilation with volume guarantee combines the advantages of pressure-controlled ventilation with guaranteed tidal volume and may improve respiratory system mechanics compared with conventional volume-controlled ventilation. However, its effect on patient-centered outcomes, such as postoperative pulmonary complications, remains unclear. In this single-center randomized controlled trial, 106 adult patients undergoing emergency laparotomy under general anesthesia with an expected duration of more than 2 hours were randomized to receive intraoperative ventilation using either pressure-controlled ventilation with volume guarantee or volume-controlled ventilation. The primary outcome was postoperative pulmonary complication assessed by the Melbourne Group Score version 2 within postoperative day 7. Secondary outcomes included intraoperative respiratory mechanics, lung ultrasound aeration score, oxygenation status, postoperative pulmonary complications according to the European Perioperative Clinical Outcome definition, oxygen-free days at day 28, duration of hospital stay, and hospital mortality. Negative binomial regression was used to estimate the effect of ventilation mode on the Melbourne Group Score version 2. Median (interquartile range) Melbourne Group Score version 2 score at postoperative day 7 was 0 (0-2) in the pressure-controlled ventilation with volume guarantee group and 1 (0-3) in the volume-controlled ventilation group, with no significant difference between groups (adjusted incidence rate ratio, 1.17; 95% confidence interval, 0.72-1.88; P = .53). Postoperative pulmonary complication defined as the Melbourne Group Score version 2 ≥ 3 occurred in 3.8% of patients in the pressure-controlled ventilation with volume guarantee group and 17% in the volume-controlled ventilation group. At 1 hour of surgery, respiratory system compliance was higher, and mechanical power and driving pressure were lower with pressure-controlled ventilation with volume guarantee, whereas oxygenation, lung aeration score, and European Perioperative Clinical Outcome-defined postoperative pulmonary complication were similar between groups. In patients undergoing emergency laparotomy, pressure-controlled ventilation with volume guarantee improved intraoperative respiratory mechanics but did not reduce postoperative pulmonary complications compared with conventional volume-controlled ventilation. As we recruited a limited number of patients, our findings need validation in a larger trial. Future studies are also required to determine whether these physiologic advantages translate into clinically meaningful benefits.