Impact of Venoarterial Extracorporeal Membrane Oxygenation Flow on Outcomes in Cardiogenic Shock

Venoarterial extracorporeal membrane oxygenation (VA ECMO) is used to provide cardiopulmonary support in cardiogenic shock; however, high extracorporeal flow may increase left ventricular (LV) afterload leading to LV distention and intracardiac stasis. It is unclear how ECMO flow affects patient outcomes and complications related to ECMO. Retrospective review of patients at a single institution placed on VA ECMO from 2007 to 2018 was performed. Patients were divided into full flow (flow index > 2.2 L/min/m2) and partial flow (flow index < 2.2 L/min/m2) groups. In-hospital mortality and markers of end-organ perfusion were compared between groups balanced for risk factors using propensity score inverse probability of treatment weighting. ECMO-related complications such as LV distention, limb ischemia, and bleeding were recorded. There were 488 patients included, 405 (83%) in the partial flow group, and 83 (17%) in the full flow group. No major differences in age, gender, or comorbidities were found. There was no difference in in-hospital mortality between groups (51% vs. 55%, p = 0.59). At 72 hours post-ECMO initiation, there was no difference in the change in renal, hepatic function, or lactate from baseline nor in the rates of continuous venoveno hemofiltration initiation (p = 0.41). There was a trend towards the decreased incidence of LV distention requiring LV vent placement in the partial flow group (12% vs. 7%, p = 0.16). Compared with full flow VA ECMO, partial flow VA ECMO in carefully selected patients results in similar in-hospital mortality and provides similar end-organ perfusion for the treatment of refractory cardiogenic shock.