Back Flow Arteriovenous Shunt Test for Weaning of Venoarterial Extracorporeal Membrane Oxygenator.

Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) has been widely applied in various cardiogenic shock (CS). However, there is a lack of consensus on the timing of weaning. Proposed algorithm is, if the patient is tolerable to minimum flow of 1-1.5/min, some echocardiographic and hemodynamic parameters are reasonable, de-cannulation could be considered. The aim of this study was to investigate the outcome of back flow shunt test our team has been done for years, which gives the transient loading condition to right ventricle before final decision of de-cannulation of VA ECMO. We retrospectively reviewed all adult VA-ECMO patients treated at a single tertiary hospital in South Korea between January 2018 to July 2019. Demographic data, diagnosis, echocardiography findings, ECMO configuration, mortality and morbidity data were collected. Backflow shunt test was done by simply reverse the Rota flow with dial to achieve negative flow from artery to vein. The test was stopped by simply dialing back to previous ECMO flow in case of unstable vital signs (Figure) Total of 47 patients underwent back-flow shunt test; 38 were de-cannulated on the 1st trial, 5 were on 2nd, 4 were on 3rd. The mean age was 58±16, 29 (63%) were male and 18 (37%) were female. The etiology of CS was ischemia 32 (70%), myocarditis 6 (13%), non-ischemic heart failure 5 (11%), refractory arrhythmia 2 (4%). All patients were successfully de-cannulated without hemodynamic deterioration. There was no thromboembolic event or oxygenator membrane thrombosis during shunt test. None of the patients needed re-insertion of VA ECMO within 3 days after weaning. In-hospital death after weaning were 4 (8.5%). Our study suggests that back-flow shunt test is a simple, and reversible weaning method applied in CS from various etiology without stopping the VA ECMO and concern of thromboembolism. This test could be effectively applied to the patients with marginal heart function. [ABSTRACT FROM AUTHOR]