A narrative review of the clinical applications of renal NIRS and integration with cerebral NIRS in the NICU.

Organ perfusion and regional tissue oxygen saturation (rSO₂) can be measured non-invasively using near-infrared spectroscopy (NIRS). While cerebral NIRS monitoring in neonates has been widely used, the adoption of renal NIRS is still evolving. This narrative review explores the application of renal NIRS in neonates and proposes an algorithm for integrating renal and cerebral NIRS in the neonatal intensive care unit. Decreased renal regional oxygenation (RrSO₂) suggests decreased renal O₂ delivery/perfusion or increased O₂ consumption, warranting evaluation for acute kidney injury, anemia, hemodynamically significant patent ductus arteriosus, or hypotension. Increased RrSO₂ indicates increased renal O₂ delivery/perfusion or decreased O₂ consumption, necessitating assessment for hyperoxia or established kidney injury. Combining cerebral and renal NIRS provides a comprehensive evaluation, allowing for the detection of early clinical changes. This integrated monitoring approach holds promise for improving neonatal outcomes. However, further large-scale studies are needed to establish normal ranges and guide therapeutic interventions.