Renal tissue oxygenation and development of AKI in preterm neonates born < 32 weeks' gestational age in the first week of age.

OBJECTIVE: To evaluate the relationship between regional renal saturation of oxygen (RrSO2) changes and serum creatinine (SCr) during the first eight days of age for preterm neonates born < 32 weeks' gestational age. DESIGN: Post-hoc analysis of multicenter prospectively measured neonatal RrSO2 values collected during the first 8 days of age in neonates born at < 32 weeks' gestation. Acute kidney injury (AKI) was defined by the neonatal modified Kidney Disease: Improving Global Outcomes (KDIGO) criteria. Variables were compared between groups of neonates with and with AKI. RESULTS: One hundred nine neonates were included and 561 SCr values were obtained. Eight participants developed AKI by SCr criteria. A 10-percentage point increase in mean %RrSO2 was associated with a 40% decrease in risk of AKI (95%CI: 9.6-61%; p = 0.016). CONCLUSIONS: Increases in mean %RrSO2 in neonates born at < 32 weeks' GA were associated with a decreased risk of AKI. These findings support the design of further prospective trials utilizing RrSO2 monitoring to evaluate new therapies or clinical protocols to prevent and treat neonatal AKI.

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

OBJECTIVE: To describe renal regional saturation of oxygen (RrSO2) values during the first week of life for preterm neonates born at <32 weeks gestational age (GA). METHODS: RrSO2 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 RrSO2 monitoring were included. Separately fitted trends in RrSO2 did not differ (p = 0.52) between sites and demonstrated a consistent decrease in RrSO2 by 20 points (95% CI: 9.6-30.1) during the first 60 h of life, followed by a stabilization of RrSO2 thereafter. RrSO2 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 RrSO2 values between sites, profiles over time are consistent, allowing for the determination of RrSO2 trajectories in preterm infants. This expected pattern of RrSO2 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 (RrSO2) slowly decreases during the first 60 h of age in <32-week preterm neonates. While site differences were identified with respect to absolute values, RrSO2 trends from two different centers were not different. Lower gestational age neonates have lower RrSO2 levels during the first week.