Association Between End-Tidal Carbon Dioxide and Pulmonary Artery Pulse Pressure During Veno-Arterial Extracorporeal Membrane Oxygenation with Impella®: A Retrospective Exploratory Study

Background: Assessment of native cardiopulmonary circulation is essential during combined veno-arterial extracorporeal membrane oxygenation (V-A ECMO) and Impella® support (ECPELLA). Pulmonary artery catheter (PAC)-derived pulmonary artery pulse pressure (PAPP) is associated with RV stroke volume and pulmonary arterial compliance; however, PAC monitoring has procedure-related risks and technical limitations. End-tidal carbon dioxide (EtCO2) is a simple, continuous, noninvasive indicator of pulmonary blood flow; however, its relationship with PAPP during ECPELLA support remains unclear. Methods: We retrospectively analyzed adult patients who underwent simultaneous ECPELLA and PAC monitoring between April 2024 and December 2025. Hemodynamic variables and EtCO2 were evaluated on ECPELLA support day 1 and on the final day of V-A ECMO support. Correlations between EtCO2 and PAPP, as well as their temporal changes during ECPELLA support, were assessed using Spearman correlation analysis. Results: Sixteen patients were included. EtCO2 showed significant positive correlations with PAPP on ECPELLA support day 1 (r = 0.63, p = 0.009), on the final day of V-A ECMO support (r = 0.67, p = 0.007), and for changes over time (ΔPAPP vs. ΔEtCO2, r = 0.76, p = 0.001). Conclusions: EtCO2 was associated with PAPP and its temporal changes during ECPELLA support. Although these findings suggest a potential role for EtCO2 in noninvasive assessment of PAPP trends, further studies in larger cohorts are needed to better characterize this relationship.