Renal oxygenation measured by near-infrared spectroscopy in preterm neonates in the first week

Objective To describe renal regional saturation of oxygen (RrSO 2 ) values during the first week of life for preterm neonates born at <32 weeks gestational age (GA). Methods RrSO 2 values recorded over the first week of life using near-infrared spectroscopy were retrospectively analyzed in this two-center cohort study of preterm infants without known congenital anomalies of the kidney. Results A cohort of 109 neonates with a median GA of 26.9 weeks and a median of 120 (IQR: 87–141) hours of continuous RrSO 2 monitoring were included. Separately fitted trends in RrSO 2 did not differ ( p = 0.52) between sites and demonstrated a consistent decrease in RrSO 2 by 20 points (95% CI: 9.6–30.1) during the first 60 h of life, followed by a stabilization of RrSO 2 thereafter. RrSO 2 baseline trends increased by 2.1 (95% CI: 0.8–3.3) percentage points for each additional week GA between 24 and 32 weeks GA. Conclusions Despite differences in adjusted RrSO 2 values between sites, profiles over time are consistent, allowing for the determination of RrSO 2 trajectories in preterm infants. This expected pattern of RrSO 2 changes in the first week may help guide future investigations and interventions to identify and reduce kidney injury in the preterm neonate. Impact Renal regional saturation of oxygen (RrSO 2 ) slowly decreases during the first 60 h of age in <32-week preterm neonates. While site differences were identified with respect to absolute values, RrSO 2 trends from two different centers were not different. Lower gestational age neonates have lower RrSO 2 levels during the first week.