Supplementary Material for: Reference values of cerebral fractional tissue oxygen extraction (cFTOE) in preterm neonates during immediate fetal-to-neonatal transition: A secondary outcome analysis of the COSGOD III trial

Background Monitoring cerebral oxygenation during immediate fetal-to-neonatal transition may provide additional information in preterm neonates. Cerebral fractional tissue oxygen extraction (cFTOE), derived from cerebral oxygen saturation (crSO2) and arterial oxygen saturation (SpO2), reflects the relative extraction of oxygen from the arterial to the tissue compartment, providing information about the balance between oxygen delivery and oxygen consumption. We aimed to describe centiles of cFTOE during the first 15 minutes after birth in extremely and very preterm neonates. Methods This is a secondary outcome parameter analysis of the multicentre randomised-controlled COSGOD III trial. Neonates <32 weeks of gestational age included in the NIRS-open-group of the COSGOD III trial with favourable outcome, defined as survival without cerebral injury at term-equivalent age, were assigned for this analysis. CFTOE was calculated for every minute in each included neonate: cFTOE = (SpO2-crSO2)/SpO2. CrSO2 was measured with the INVOS 5100 monitor with the neonatal sensor. Centiles of cFTOE (10th to 90th) from minute two to 15 after birth were described. Results A total of 199 preterm neonates with a median (IQR) gestational age of 29.7 (27.7-30.9)weeks and a weight of 1200 (925-1460)grams were analysed. The 50th centile of cFTOE at minute two, five, ten and 15 was 0.492, 0.296, 0.177 and 0.151, respectively. Conclusion This study provides centile for cFTOE for extremely and very preterm neonates with favourable outcome independent of interventions during postnatal stabilisation period. These centile charts may assist in interpreting cerebral oxygenation patterns.