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

Background: 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 FiO(2), and peak inspiratory pressure) and the occurrence of PPCs. Methods: 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. Results: 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 FiO(2) was 0.5 (IQR: 0.44-0.53), and an increase in FiO(2) by 5% increased the risk of developing a PPC by 8% (2.6-14.1%; P=0.008). Conclusions: Both intraoperative peak inspiratory pressure and FiO(2) 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.