Regional cerebral oxygen saturation references in extremely and very preterm neonates using neonatal sensors: a prospective observational cohort study

Abstract

Objective: Reference values of regional cerebral oxygen saturation (rScO₂) in preterm neonates across gestational age (GA) groups remain undefined. This study aimed to establish rScO₂ 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: rScO₂ was assessed with near-infrared spectroscopy (NIRS) using neonatal sensors.

Main outcome measures: The primary analysis provided rScO₂ 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 rScO₂ 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 rScO₂ 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 rScO₂ observed in the VP_>30-32w group. Supplementary analyses, comparing rScO₂ values across the three GA groups, revealed significant differences at 48 and 72 hours. The majority of the estimated rScO₂ 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 rScO₂ was above the brain hypoxic threshold.

Conclusions: The use of age-appropriate neonatal NIRS sensors provided the rScO₂ reference values for very and extremely preterm neonates without major comorbidities 6-72 hours after birth.

Keywords: Neonatology.

Figure 1. Flow diagram of the study participants. Abbreviations: CDH, congenital diaphragmatic hernia; CHD, congenital heart disease; d-TGA, dextro-transposition of the great arteries; cUS, cranial ultrasound; IUGR, intrauterine growth restriction; TTTS, twin-to-twin transfusion syndrome; FIRS, fetal inflammatory response syndrome.

Figure 2. Quantile regression estimates for the selected percentiles of rScO₂ during the first 72 hours for the entire preterm neonate cohort. Abbreviations: NIRS, near-infrared spectroscopy; rScO₂, regional cerebral oxygen saturation.

Figure 3. Quantile regression estimates for selected percentiles of rScO₂ during the first 72 hours of life according to gestational age (GA): (A) <28.0 weeks, (B) 28.0–30.0 weeks and (C) 30.1–32.0 weeks. Abbreviations: NIRS, near-infrared spectroscopy; rScO₂, regional cerebral oxygen saturation.

Figure 4. Quantile regression estimates for the median rScO₂ during the first 72 hours of life according to gestational age. Abbreviations: NIRS, near-infrared spectroscopy; rScO₂, regional cerebral oxygen saturation.

Figure 5. Quantile regression estimates for the selected percentiles of rScO₂ during the first 72 hours of life according to the type of respiratory support: (A) nCPAP and (B) mechanical ventilation. Abbreviations: nCPAP, nasal continuous positive airway pressure; NIRS, near-infrared spectroscopy; rScO₂, regional cerebral oxygen saturation.

Figure 6. Quantile regression estimates for the median rScO₂ during the first 72 hours of life according to the requirement for respiratory support. Abbreviations: nCPAP, nasal continuous positive airway pressure; NIRS, near-infrared spectroscopy; rScO₂, regional cerebral oxygen saturation.