Background: Venoarterial extracorporeal membrane oxygenation (VA-ECMO) can easily lead to supranormal oxygenation. The impact of hyperoxygenation beyond the early VA-ECMO support phase is unexplored. We sought to investigate its association with short- and long-term mortality. 

Methods: A total of 10,615 arterial blood gases of 179 patients undergoing VA-ECMO between 2013 and 2018 in our cardiosurgical tertiary center were analyzed for partial pressure of oxygen (PaO₂) and its association with in-hospital, 90-day, and 1-year mortality. Patients were stratified into terciles (T) based on PaO₂. 

Results: The median systemic PaO₂ during VA-ECMO was 122 mm Hg (Q1–Q3, 111–158 mm Hg) and was significantly higher in 90-day nonsurvivors versus survivors (134 mm Hg [Q1–Q3, 114–175 mm Hg] vs. 114 mm Hg [Q1–Q3, 109–136 mm Hg]; P < 0.001). The incidence of mortality increased at all time points tested after VA-ECMO implantation along with the increasing terciles of PaO₂. The lowest mortality rates were noted for patients with median PaO₂ values of <115 mm Hg (T1), whereas patients with median PaO₂ values of >144 mm Hg (T3) had the highest mortality rates. Bonferroni multiple testing analysis found the T3 of PaO₂ to be a predictor of decreased 90-day survival in comparison with T1 (P < 0.001) and T2 (P = 0.002). Multivariable Cox regression analyses for in-hospital, 90-day, and 1-year mortality showed a significant association of the T3 compared with the T2 and the T1 of PaO₂ to mortality across all endpoints. 

Conclusion: Hyperoxygenation during VA-ECMO might be associated with increased all-cause mortality. The results of our study further document the known toxicity of hyperoxygenation in general critical care patients and mark the need to focus specifically on VA-ECMO patients.