Aortic arch blood flow measurements as a predictor of successful ECMO weaning in cardiogenic shock

Objective: Acute cardiogenic shock is a life-threatening condition with mortality rates of up to 50%. If conventional therapy fails, veno-arterial extracorporeal membrane oxygenation (VA-ECMO) therapy has emerged to a promising alternative for temporary cardiac and respiratory support in specialized centers. However, it is only a bridge to recovery, final decision, heart transplantation or the permanent implantation of a left ventricular assist device. Therefore, the identification of the optimum weaning time point is challenging, and standardized weaning protocols are rare. Methods: In this explorative pilot study, we evaluated the potential benefit of blood flow measurements in the aortic arch using an ultrasonic cardiac output monitor (USCOM) for the primary endpoint of successful VA-ECMO weaning. 12 patients under VA-ECMO therapy for acute cardiogenic shock and a hemodynamic condition which qualified for a stepwise weaning process were included in this study. Main exclusion criterion was the presence of additional venting therapy for left ventricular unloading, e.g. Impella. Statistical comparisons were performed using the Mann-Whitney test and corrected for multiple testing by the Holm-Sidak method. Results: Peak velocity of flow in the aortic arch showed a positive correlation with weaning success independent of ECMO flow (weaning success vs. failure: 0.75 vs. 0.35 m/s (low ECMO support), p = 0.049), whereas we identified only a trend for mean pressure gradient, minute distance and stroke volume index. Conclusion: We hypothesize, that USCOM might provide an additive benefit to conventional strategies in its ability to predict successful VA-ECMO weaning and prevent pulmonary congestion. Larger upcoming trials are required to address this relevant topic and provide standardized treatment protocols for optimized weaning in the future.