Acute Kidney Injury is a Frequent Complication in Critically Ill Neonates on Extracorporeal Membrane Oxygenation: A 14-year Cohort Study

INTRODUCTION:

Newborns in need of extracorporeal membrane oxygenation (ECMO) support are at high risk of developing acute kidney injury (AKI). AKI may occur as part of multiple organ failure and can be aggravated by exposure to components of the extracorporeal circuit. AKI necessitates adjustment of dosage of renally eliminated drugs and avoidance of nephrotoxic drugs. We aimed to systematically define the incidence and clinical course of AKI in critically ill neonates receiving ECMO support.

METHODS:

This study reviewed prospectively collected clinical data (including age, diagnosis, ECMO course, and serum creatinine [SCr]) of all ECMO-treated neonates within our institution spanning a fourteen-year period. AKI was defined using the Risk, Injury, Failure, Loss of renal function, and End-stage renal disease (RIFLE) classification. SCr data were reviewed per ECMO day and compared to age-specific SCr reference values. Accordingly, patients were assigned to RIFLE categories (Risk, Injury, or Failure as 150%, 200% or 300% of median SCr reference values). Data are presented as median and interquartile range (IQR) or number and percentage (%).

RESULTS:

242 patients were included of whom 179 survived (74%). Median age at start ECMO was 39 hours [IQR 26 – 63]; median ECMO duration was 5.8 days [IQR 3.9 – 9.4]. 153 patients (64%) had evidence of AKI, with 72 (30%) qualifying as Risk, 55 (23%) as Injury and 26 (11%) as Failure. At the end of the study period only 71 patients (46%) out of all 153 AKI patients improved at least one RIFLE category. Using regression analysis it was found that nitric oxide ventilation (p=0.04) and younger age at start ECMO (p=0.004) were significant predictors of AKI. Survival until intensive care unit discharge was significantly lower for patients in the Failure category (35%) as compared to the Non-AKI (78%), Risk (82%) and Injury category (76%), with all p<0.001, while there were no significant differences between the three latter RIFLE categories.

CONCLUSIONS:

Two thirds of neonates on ECMO suffered from AKI, with a significantly increased mortality risk for patients in the Failure category. As AKI during childhood may predispose for chronic kidney disease in adulthood, long-term monitoring of kidney function after ECMO is warranted.