Radoš, Milan

Objective Reference values of regional cerebral oxygen saturation (rScO 2 ) in preterm neonates across gestational age (GA) groups remain undefined. This study aimed to establish rScO 2 references for neonates born before 32 weeks of gestation. Design A prospective observational cohort study. Setting Large tertiary neonatal referral centre in Croatia. Patients Preterm neonates without major comorbidities born between 2018 and 2022 with normal cranial ultrasound findings. Interventions rScO 2 was assessed with near-infrared spectroscopy (NIRS) using neonatal sensors. Main outcome measures The primary analysis provided rScO 2 reference ranges for the entire preterm neonatal cohort, followed by stratified analyses based on GA: extremely preterm , <28.0 weeks; very preterm , 28.0–30.0 weeks; and very preterm , 30.1–32.0 weeks. Quantile regression was used to estimate the selected rScO 2 percentiles (5th, 10th, 50th, 90th and 95th) from 6 to 72 hours after birth. Results 114 neonates with median (IQR) GA of 29.9 (29.1–31.5) weeks were included: 22% were EP <28w , 29% were VP 28–30w and 49% were VP >30–32w . The median rScO 2 was 75.6% at 6 hours, 79.5% over the first 24 hours and exceeding 80% in the subsequent 48 hours. When analysed separately, notable differences emerged across prematurity categories, with the highest median rScO 2 observed in the VP >30–32w group. Supplementary analyses, comparing rScO 2 values across the three GA groups, revealed significant differences at 48 and 72 hours. The majority of the estimated rScO 2 fifth percentiles between 6 and 72 hours were in the range ≥60%, with a single lowest estimate of 56.3% at 6 hours in the EP <28w group. Thus, for all subgroups, the estimated fifth percentile of rScO 2 was above the brain hypoxic threshold. Conclusions The use of age-appropriate neonatal NIRS sensors provided the rScO 2 reference values for very and extremely preterm neonates without major comorbidities 6–72 hours after birth.