Early ECMO Flow Index and Arterial Oxygenation Targets and Outcomes in Adults With Cardiogenic Shock Supported With Venoarterial Extracorporeal Membrane Oxygenation

Abstract

Cardiogenic shock (CS) is a life-threatening syndrome characterized by reduced cardiac output and end-organ hypoperfusion, with in-hospital mortality nearing 50% despite contemporary therapies. Venoarterial extracorporeal membrane oxygenation (VA-ECMO) has emerged as a key rescue strategy in refractory CS, providing temporary circulatory support to restore adequate perfusion. However, its use is associated with a high risk of significant complications, including bleeding, thromboembolism, neurologic injury, and limb ischemia. ECMO flow index and arterial oxygenation are readily modifiable parameters during VA-ECMO support that may influence outcomes. Although full flows (>2.0–2.2 L/min/m²) are commonly targeted, they may increase left ventricular (LV) afterload, impair myocardial recovery, and reduce pulsatile flow. Conversely, partial flows may preserve native ejection, reduce vascular complications, and minimize the need for LV unloading. Additionally, arterial hyperoxia, driven by high oxygen delivery through the membrane oxygenator, has been associated with adverse outcomes, including increased mortality, possibly due to oxidative stress and arterial vasoconstriction. ECMO flows can contribute to the absolute oxygen exposure through shifts in the aortic mixing zone that may expose vital circulations (e.g. coronary, cerebral) to supraphysiologic oxygen levels. In this thesis, we leveraged data from the Extracorporeal Life Support Organization (ELSO) Registry to examine two interrelated questions. In the first study, we assessed whether initial ECMO flow index was associated with in-hospital mortality, metrics of perfusion, and major complications. In the second study, we evaluated the interaction between flow index and arterial oxygenation and their impact on outcomes. Together, these analyses aim to inform future strategies for optimizing VA-ECMO support in adults with CS.