Lung compliance and outcomes in patients with acute respiratory distress syndrome receiving ECMO

Abstract Background Limited data are available regarding mechanical ventilation strategies in patients with acute respiratory distress syndrome (ARDS) receiving extracorporeal membrane oxygenation (ECMO). Methods A retrospective analysis of ARDS patients on ECMO was conducted in nine hospitals in Korea. Data on ventilator settings (pre-ECMO, and 0, 4, 24, 48 hours after ECMO) were collected. Based on the effect of the duration and intensity of mechanical ventilator on outcomes, time-weighted average (TWA) values were calculated for ventilator parameters. Results The 56 patients included in the study had a mean age of 55.5 years. The hospital and 6-month mortality rates were 48.1% and 54.0%, respectively, with a median ECMO duration of 9.4 days. After initiation of ECMO, peak inspiratory pressure, above positive end-expiratory pressure, tidal volume, and respiration rate were reduced, while lung compliance did not change significantly. Before and during ECMO support, tidal volume and lung compliance were higher in 6-month survivors than in non-survivors. In Cox proportional models, both lung compliance (odds ratio, 0.961; 95% confidence interval, 0.928–0.995) and TWA-lung compliance (0.943; 0.903–0.986) were significantly associated with 6-month mortality. Kaplan-Meier curves revealed that patients with higher lung compliance before ECMO had a longer survival time at the 6-month follow-up than those with lower lung compliance. Conclusions Lung compliance, whether before or during ECMO, may be an important predictor of outcome in ARDS patients receiving ECMO. However, this result requires confirmation in larger clinical studies.