Renal Oxygenation Measured by Near-Infrared Spectroscopy in Neonates

Background: Acute kidney injury (AKI) affects approximately 30% of infants admitted to the neonatal intensive care unit (NICU), and increases mortality risk by 50%. Current diagnostic criteria (serum creatinine rise with oliguria) cannot detect early-onset AKI, as up to 50% of nephron damage may occur by the time these abnormalities present. Once AKI is established, clinical management is often ineffective; therefore, prevention is key. Near-infrared spectroscopy (NIRS) offers a feasible, noninvasive approach to continuously monitor renal oxygenation trends over time, serving as a surrogate marker for renal perfusion. Purpose: To provide an overview of NIRS principles for measuring renal oxygenation, and to describe current evidence of how this technology is being used among infants admitted to the NICU relative to the prediction and identification of AKI. Methods: A comprehensive search of PubMed and CINHAL focused on renal NIRS studies in NICU preterm and term infants was conducted. Results: Findings from 34 studies were included. In term infants, reduced renal oxygenation correlated to invasive SvO²monitoring, predicted survivability and AKI. In preterm infants, reduced renal oxygenation was associated with AKI in one study, yet contrasting findings were reported in those with patent ductus arteriosus, including those who received prostaglandin inhibitors. Normative data in all infants were sparse. Implications for Practice: Renal NIRS may offer a noninvasive measurement of kidney hypoperfusion that may precede conventional diagnostic measures. Implications for Research: Normative data are lacking, the threshold for renal ischemia is not defined, and consensus guiding clinical treatment based on NIRS data is nonexistent.