OBJECTIVE

To describe renal regional saturation of oxygen (RrSO) values during the first week of life for preterm neonates born at <32 weeks gestational age (GA).

METHODS

RrSO 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 monitoring were included. Separately fitted trends in RrSO did not differ (p = 0.52) between sites and demonstrated a consistent decrease in RrSO by 20 points (95% CI: 9.6-30.1) during the first 60 h of life, followed by a stabilization of RrSO thereafter. RrSO 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 values between sites, profiles over time are consistent, allowing for the determination of RrSO trajectories in preterm infants. This expected pattern of RrSO 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) 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 trends from two different centers were not different. Lower gestational age neonates have lower RrSO levels during the first week.