To assess whether prone positioning (PP) increases bleeding risk compared to supine positioning in ARDS patients undergoing veno venous Extracorporeal Membrane Oxygenation (VV ECMO).

A single-center retrospective observational study was conducted between January 2012 and March 2023. Data were systematically collected from an institutional ECMO registry, including baseline characteristics, daily variables, bleeding events, and outcomes. We compared the relative risk (RR) and incidence rate ratio (IRR) of bleeding between ‘Prone‘ and ‘Supine‘ patients. Bleeding-free days were analyzed using Kaplan-Meier curves and the Log-Rank test.

We included 136 consecutive severe ARDS patients undergoing VV ECMO (65% male, age 52 ± 11, 53% bacterial pneumonia), with 85 (62%) and 51 (38%) in the ‘Prone’ and ‘Supine’ group respectively. Bleeding occurred in 79 (58%) patients, with 43 of these being major bleeding events, including 14 intracranial hemorrhages. Fifty-two (61%) ‘Prone’ patients versus 27 (53%) ‘Supine’ patients had bleeding (RR 1.11 (95% CI: 0.81–1.52), p = .44; IRR 1.08 (95% CI: 0.68–1.75), p = .75), with a tendency towards lower major bleeding incidence in the ‘Prone’ versus ‘Supine’ patients (IRR 0.54 (95% CI: 0.29–1.03), p = .06). Kaplan-Meier survival analysis showed no significant difference in bleeding-free days between the ‘Prone’ and ‘Supine’ groups (p = .11).

PP during VV ECMO for ARDS was not associated with an increased incidence of bleeding. Further prospective studies are warranted to confirm these findings.