ID:37 OA2-3 Impact of Prone Positioning Before Veno-Venous ECMO on Clinical Outcomes in Severe ARDS: A Multicenter Propensity-Matched Study

Background: Prone positioning (PP) improves oxygenation and survival in severe acute respiratory distress syndrome (ARDS), while veno-venous extracorporeal membrane oxygenation (V-V ECMO) is an established rescue therapy. However, the clinical impact of PP before V-V ECMO initiation remains unclear. Methods: This post hoc analysis used data from the Japan Chest Computed Tomography for ARDS Requiring V-V ECMO (J-CARVE) registry, a multicenter retrospective cohort study conducted at 24 institutions between 2012 and 2022. Adult patients with severe ARDS who received V-V ECMO were included. Patients were categorized according to whether PP was performed before V-V ECMO initiation. The primary outcome was successful liberation from V-V ECMO within 30 days. Multivariable Cox proportional hazards models and propensity score matching (PSM) were used to adjust for potential confounders. Results: Among 690 patients, 128 received PP before V-V ECMO initiation and 562 did not. Successful liberation from V-V ECMO within 30 days occurred in 67.1% of the PP group and 69.2% of the non-PP group. Kaplan–Meier analysis showed no significant difference between groups. In the adjusted Cox model, PP before V-V ECMO was not associated with successful liberation (adjusted hazard ratio [HR] 1.03; 95% confidence interval [CI] 0.78–1.37). After PSM (108 matched pairs), liberation rates remained similar (68.5% vs. 63.8%), with no significant association observed (adjusted HR 1.20; 95% CI 0.85–1.69). No significant differences were found in mortality or other secondary outcomes. Conclusion: In patients with severe ARDS requiring V-V ECMO, prone positioning before ECMO initiation was not associated with improved short-term clinical outcomes. Prospective studies are needed to clarify the optimal timing and role of prone positioning in patients considered for V-V ECMO.