Is pulse pressure a mediator in the relationship between hyperoxemia and acute brain injury in veno-arterial extracorporeal membrane oxygenation (VA-ECMO) patients? An ELSO registry study.

IntroductionHyperoxemia is associated with increased mortality and acute brain injury (ABI) in patients receiving veno-arterial extracorporeal membrane oxygenation (VA-ECMO), though the role of native cardiac function in this relationship is unclear. Pulse pressure (PP) can reflect the proximal shift of dual circulation between ECMO and native heart function. We aimed to investigate the relationship between PP, hyperoxemia, and ABI.MethodsWe included adults (≥18 years) receiving peripheral VA-ECMO for cardiogenic shock from the ELSO Registry (2013-2024).ResultsABI occurred in 1012/8486 (11.9%) patients. In multivariable logistic regression adjusting for demographic and clinical covariates, severe hyperoxemia (PaO2 ≥ 300 mmHg) remained independently associated with ABI (aOR: 1.40, 95% CI: 1.04-1.86). Low pulse pressure (PP) was more frequent among ABI patients, but PP was not independently associated with ABI after adjustment (aOR: 1.01, 95% CI: 0.81-1.25). PaO2 and PP were inversely related. In mediation analysis PP accounted for 8.2% of the total effect of hyperoxemia on ABI overall (14% in the non-LV-vented cohort).ConclusionSevere hyperoxemia during ECMO was associated with increased ABI risk. Low PP was not. PP mediated the relationship between hyperoxemia and ABI. Reduced cardiac function may drive proximal dual circulation shift, predisposing patients to hyperoxemia and ABI. Hyperoxemia appears modifiable, and improved PP may reduce ABI.