Acute Kidney Injury Timing May Influence VA-ECMO Outcomes

ACUTE kidney injury (AKI) timing may help inform prognostic assessment in adults receiving veno-arterial extracorporeal membrane oxygenation (VA-ECMO), with a two-centre study finding higher unadjusted intensive care unit (ICU) mortality among patients who developed AKI before ECMO initiation. However, this association weakened after adjustment for patient characteristics and illness severity, highlighting the importance of considering the broader clinical context when assessing outcomes. 

Acute Kidney Injury Timing and Study Design 

Researchers evaluated the relationship between AKI timing and clinical outcomes in a retrospective cohort of 172 adults receiving VA-ECMO across two centres in Thailand. Patients were classified according to Kidney Disease: Improving Global Outcomes (KDIGO) creatinine criteria as having AKI before ECMO, AKI after ECMO initiation, or no AKI. 

Of the 172 patients, 81 (47.1%) developed AKI before ECMO, while 82 (47.7%) developed AKI after initiation. Only nine patients (5.2%) had no AKI. The findings addressed an important clinical question: whether the timing of renal injury provides independent prognostic information in patients requiring this form of circulatory support. 

Pre-ECMO Kidney Injury and Mortality 

Patients with AKI before ECMO presented with more severe renal dysfunction and required renal replacement therapy more frequently than those who developed AKI after ECMO initiation. Acute liver injury was also more common in the pre-ECMO group. 

Unadjusted ICU mortality was higher among patients with AKI before ECMO than among those developing AKI afterwards, at 82.7% versus 69.5%, respectively (p=0.048). 

However, the association between pre-ECMO AKI and mortality became less pronounced following statistical adjustment. After accounting for age, sex, chronic kidney disease, and centre, the adjusted hazard ratio was 1.39 (95% confidence interval: 0.98–1.98). Further adjustment for illness severity reduced the hazard ratio to 1.28 (95% confidence interval: 0.86–1.90). Neither adjusted estimate established a statistically significant association. AKI developing after ECMO initiation was also not significantly associated with ICU mortality. 

Implications for ECMO Candidacy Assessment 

The findings suggest that AKI preceding ECMO may reflect not only renal injury but also pre-cannulation shock and multiple organ dysfunction. This distinction is clinically relevant because the observed mortality difference could partly reflect the severity of the patient’s underlying condition rather than the timing of kidney injury alone. 

For clinicians assessing patients for VA-ECMO, the results support considering renal function alongside overall illness severity and evidence of other organ injury. Pre-ECMO AKI may provide useful prognostic context, but the findings do not establish it as an independent predictor of ICU mortality after adjustment. 

The researchers concluded that the timing of AKI should inform ECMO candidacy assessment rather than serve as a reason to restrict access to treatment. Further evidence would help clarify the independent prognostic value of AKI timing in this patient population. 

Reference 

Jungteerapanich T et al. Timing of acute kidney injury and outcomes in patients receiving veno-arterial extracorporeal membrane oxygenation. Sci Rep. 2026;DOI:10.1038/s41598-026-77261-7.