Background AKI is a frequent concomitant organ failure during veno-venous extracorporeal membrane oxygenation (VV-ECMO). This study investigated the prevalence and the impact of AKI on survival to hospital discharge and up to
1 year after discharge and risk factors for developing AKI during VV-ECMO.
Methods This is an observational retrospective study of 500 consecutive patients receiving VV-ECMO between November 2014 and December 2021. Patients were divided into three groups: (1) AKI onset before extracorporeal membrane oxygenation (ECMO), (2) AKI onset during ECMO, and (3) AKI onset before and new onset during ECMO. The Kidney Disease Improving Global Outcomes definition was used to define AKI. Follow-up was 1 year after hospital discharge. Propensity score matching was performed for patients without AKI and patients with AKI onset during ECMO to analyze risk factors for AKI onset during VV-ECMO.
Results A total of 320 patients (64.0%) had AKI: 182 (36.4%) with onset before ECMO and 158 (31.6%) with onset during ECMO. At ECMO initiation, patients with AKI onset before VV-ECMO presented significantly higher inflammatory markers and higher NE dosage, whereas patients developing AKI during VV-ECMO did not differ from those without AKI. Survival to hospital discharge was 67.0% (AKI, 60.9%; no AKI, 77.8%; P , 0.001). Cox regression analysis revealed AKI Kidney Disease Improving Global Outcomes stage 3, independent from onset, as an independent risk factor for reduced survival to hospital discharge (hazard ratio, 2.15; 95% confidence interval, 1.37 to 3.37; P 5 0.001). During follow-
up, the survival was 92.5%; age was shown as the sole risk factor for reduced survival in hospital survivors in the multivariate logistic regression model. In the propensity score–matched cohort (41 patients in each group), the AKI group had lower mean arterial pressure and significantly higher C-reactive protein levels the days before AKI. Factors associated with VV-ECMO support (blood flow, cell-free hemoglobin) did not differ.
Conclusions Severe AKI is associated with reduced hospital survival, regardless of whether it occurs before or during ECMO. AKI onset during VV-ECMO is less because of ECMO-related factors than to recurrent septic episodes.