Reference Ranges for Cerebral Tissue Oxygen Saturation Index in Term Neonates during Immediate Neonatal Transition after Birth

Abstract

Background: Non-invasive monitoring of the brain with near-infrared spectroscopy (NIRS) during immediate transition after birth is of growing interest. Objective: The aim of this work was to define reference ranges and centile charts for a regional cerebral tissue oxygenation index (cTOI), measured with the NIRO 200NX (NIRO, Hamamatsu, Japan), and cerebral fractional tissue oxygen extraction (cFTOE) during the first 15 min after birth in preterm and term neonates without any medical support. Methods: cTOI was measured with the NIRO 200NX during the first 15 min after delivery via Caesarean section in preterm and term infants. The NIRS-sensor was placed on the right forehead. Peripheral arterial oxygen saturation (SpO₂) and heart rate were continuously measured by pulse oximetry. cFTOE was calculated out of cTOI and SpO₂. Neonates with a requirement for any medical support were excluded. Results: A total of 230 neonates were enrolled, from which 90 had to be excluded. Therefore, 140 term neonates were included and data were used to define reference ranges and centile charts. The 50th centile (10th to 90th centiles) of cTOI was 56% (39-75) at 2 min, 66% (50-78) at 5 min, 75% (62-85) at 10 min and 73% (61-84) at 15 min after birth. The 50th centile of cFTOE was 0.24 (0.11-0.44) at 2 min, 0.20 (0.10-0.35) at 5 min, 0.21 (0.09-0.35) at 10 min and 0.24 (0.13-0.37) at 15 min after birth. Conclusion: The present observational study adds the reference ranges and centile charts of cTOI measured with the NIRO 200NX and cFTOE calculated out of cTOI and SpO₂ in neonates during the immediate neonatal transition. Centiles for each instrument will be necessary for future clinical application, since the differences between cTOI and cerebral regional tissue oxygen saturation measured with INVOS 5100C change with increasing regional oxygenation.