Abstract 4123371: Hyperoxia is not a significant predictor of ICU mortality and is likely a surrogate parameter for reduced native cardiac function in patients supported with VA-ECMO

Intro: Hyperoxia has been associated with adverse outcomes in VA-ECMO patients. Whether hyperoxia represents a mechanism of mortality or is a surrogate for worse cardiac function is unknown. Aim: To determine patient characteristics, lab values, and hemodynamic parameters associated with increased mortality in VA-ECMO patients. Methods: Single-center retrospective cohort study at UCSF in VA-ECMO patients (2020-2023). Patients were categorized into 3 groups: Dead, Advanced Therapy-Free Survivors, and Advanced Therapy Survivors (survived to ICU discharge with LVAD or heart transplant). Wilcox rank sum and two sample proportion tests were performed. In-hospital mortality was evaluated using multiple logistic regression. Results: Of 179 patients, 87 died and 92 survived to ICU discharge. Of the survivors, 22 received advanced therapies. Compared to Advanced Therapy-Free Survivors, Dead patients had higher PaO2 levels (297[95% CI,164-400], p = 0.01). Dead and Advanced Therapy Survivors groups had similarly high PaO2 levels, but the latter group showed less acidosis and were more likely to have HFrEF (59%; 13/22; p = 0.02). ECMO support and VIS scores were similar. The multivariate model showed PaO2 is not associated with mortality (adjusted OR, 1.002 [95% CI, 0.99-1.004]; p = 0.131). Conclusion: Hyperoxia was associated with both death and advanced therapies, but did not predict mortality in a multivariate model. Advanced therapy survivors and patients that died were more likely to have HFrEF, suggesting that high PaO2 at cannulation reflects a proximal mixing cloud due to weak native cardiac function. Future work will analyze ECHO parameters to examine the association between hyperoxia and reduced cardiac output in VA-ECMO patients.