Adoption of Lung Protective ventilation IN patients undergoing Emergency laparotomy: the ALPINE study. A prospective multicentre observational study.

Abstract

Emergency abdominal surgery is associated with a high risk of postoperative pulmonary complications (PPCs). The primary aim of this study was to determine whether patients undergoing emergency laparotomy are ventilated using a lung-protective ventilation strategy employing tidal volume ≤8 ml kg^-1 ideal body weight^-1, PEEP >5 cm H₂O, and recruitment manoeuvres. The secondary aim was to investigate the association between ventilation factors (lung-protective ventilation strategy, intraoperative FiO₂, and peak inspiratory pressure) and the occurrence of PPCs. Data were collected prospectively in 28 hospitals across London as part of routine National Emergency Laparotomy Audit (NELA). Patients were followed for 7 days. Complications were defined according to the European Perioperative Clinical Outcome definition. Data were collected from 568 patients. The median [inter-quartile range (IQR)] tidal volume observed was 500 ml (450-540 ml), corresponding to a median tidal volume of 8 ml kg^-1 ideal body weight^-1 (IQR: 7.2-9.1 ml). A lung-protective ventilation strategy was employed in 4.9% (28/568) of patients, and was not protective against the occurrence of PPCs in the multivariable analysis (hazard ratio=1.06; P=0.69). Peak inspiratory pressure of <30 cm H₂O was protective against development of PPCs (hazard ratio=0.46; confidence interval: 0.30-0.72; P=0.001). Median FiO₂ was 0.5 (IQR: 0.44-0.53), and an increase in FiO₂ by 5% increased the risk of developing a PPC by 8% (2.6-14.1%; P=0.008). Both intraoperative peak inspiratory pressure and FiO₂ are independent factors significantly associated with development of a postoperative pulmonary complication in emergency laparotomy patients. Further studies are required to identify causality and to demonstrate if their manipulation could lead to better clinical outcomes.