Renal versus cerebral saturation trajectories: the perinatal transition in preterm neonates.

Background: The aim of this study was to develop reference renal saturation (rSrO ₂ ) curves in premature infants, depict how they differ from cerebral saturation (rScO ₂ ) curves, and evaluate the effect of blood pressure on these values using near-infrared spectroscopy (NIRS).
Methods: This is a prospective cohort study of 57 inborn infants <12 h and <30 weeks gestation. rScO ₂ , rSrO ₂ , fractional tissue oxygen extraction (FTOE), and mean arterial blood pressure (MAP) were continuously monitored every 30 s for 96 h. Quantile regression was used to establish nomograms, and mean saturation values were evaluated for different MAP ranges.
Results: Median rSrO ₂ at the start of monitoring was ~10% higher than rScO ₂ . rSrO ₂ showed a significant decline over time while rScO ₂ peaked at 26 h. FTOE demonstrated a similar but inverse trend to their saturation counterparts. rScO ₂ declined as MAP increased, while rSrO2 showed a peak and decline as MAP increased.
Conclusions: We provide rSrO ₂ reference curves for the first 4 days of life, which differ in their trajectory from rScO ₂ and from what has previously been reported for rSrO ₂ in the full-term population. In addition, we observed a peak and decline in renal saturation with increasing MAP, suggesting a renovascular response to blood pressure changes.
Impact: This article depicts reference renal saturation curves during the perinatal transition in preterm infants. We show how renal saturation compares to cerebral saturation trends over time. We describe a peak and decline in renal saturation with increasing MAP, suggesting a renovascular response to blood pressure changes.
(© 2022. The Author(s), under exclusive licence to the International Pediatric Research Foundation, Inc.)