EMPROVING Outcomes: Evaluating the Effect of an Ultra-Lung Protective Strategy for Patients with ARDS Treated with ECMO

Abstract

Purpose While there is much discussion about selection of patients for ECLS for acute respiratory distress syndrome (ARDS), little is said about the impact that ventilator management after cannulation might have on outcomes. We hypothesized that failure to properly protect the lungs after cannulation would lead to higher mortality. Methods A retrospective chart review was performed on all patients undergoing venovenous (VV) ECLS at a single center from Jan 2014 to July 2018. We evaluated the impact of ventilator management during ECLS on mortality by evaluating three variables obtained during ECLS support: the mean peak inspiratory pressure (PIP), FiO2, and respiratory rate. Results 54 patients underwent VV ECLS for ARDS . Bivariate analysis (Table) revealed a significant association with higher total bilirubin , lower mean arterial pressure & higher total days on ECLS in those who died vs. those who lived. During ECLS higher mean PIP & higher FiO2 were found in those who died. In multivariate analysis increasing age was predictive of mortality (OR 1.2; CI 1.04-1.39, p=0.02) while higher pre-cannulation serum hemoglobin was protective (OR = 0.42, CI 0.18-0.98, p=0.04). The mean PIP & the mean FiO2 during ECLS were both predictive of increased risk of mortality (PIP; OR 1.40, CI 1.03-1.89, p=0.03;FiO2; OR 1.16, CI 1.02-1.32, p =0.02). Conclusion The use of the EMPROVE protocol is significantly associated with survival in this study. As our patients’ PIP & FiO2 during ECLS more closely approximated the EMPROVE protocol criteria, survival increased. For every 1 mmHg increase in the mean peak pressure the risk of dying increased 1.4x, and for every 1% increase in the mean FiO2 during ECLS the risk of dying increased 1.16x. For lung rest to truly be effective, the lungs must be relieved of the burden of gas exchange. If gas exchange is not adequate with simple VV configuration, alternatives for gas exchange should be sought such as switching to venoarterial, rather than increasing the burden on the lungs.