Renal oximetry for early acute kidney injury detection in neonates with hypoxic ischemic encephalopathy receiving therapeutic hypothermia

Background Neonates with hypoxic ischemic encephalopathy (HIE) receiving therapeutic hypothermia are at high risk of acute kidney injury (AKI). Methods We performed a two-site prospective observational study from 2018 to 2019 to evaluate the utility of renal near-infrared spectroscopy (NIRS) in detecting AKI in 38 neonates with HIE receiving therapeutic hypothermia. AKI was defined by a delayed rate of serum creatinine decline (< 33% on day 3 of life, < 40% on day 5, and < 46% on day 7). Renal saturation ( R sat ) and systemic oxygen saturation (SpO2) were continuously measured for the first 96 h of life (HOL). Renal fractional tissue oxygen extraction (RFTOE) was calculated as (SpO2 − R sat )/(SpO2). Using renal NIRS, urine biomarkers, and perinatal factors, logistic regression was performed to develop a model that predicted AKI. Results AKI occurred in 20 of 38 neonates (53%). During the first 96 HOL, R sat was higher, and RFTOE was lower in the AKI group vs. the no AKI group ( P < 0.001). R sat > 70% had a fair predictive performance for AKI at 48–84 HOL (AUC 0.71–0.79). RFTOE ≤ 25 had a good predictive performance for AKI at 42–66 HOL (AUC 0.8–0.83). The final statistical model with the best fit to predict AKI (AUC = 0.88) included RFTOE at 48 HOL ( P = 0.012) and pH of the infants’ first postnatal blood gas ( P = 0.025). Conclusions Lower RFTOE on renal NIRS and pH on infant first blood gas may be early predictors for AKI in neonates with HIE receiving therapeutic hypothermia. Graphical abstract A higher resolution version of the Graphical abstract is available as Supplementary information