Reference Values of Cerebral Fractional Tissue Oxygen Extraction in Preterm Neonates during Immediate Foetal-to-Neonatal Transition: A Secondary Outcome Analysis of the COSGOD III Trial

INTRODUCTION: Monitoring cerebral oxygenation during immediate foetal-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 min 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 near-infrared spectroscopy-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 2 to 15 after birth were described.

RESULTS: A total of 199 preterm neonates with a median (interquartile range) gestational age of 29.7 (27.7-30.9) weeks and a weight of 1,200 (925-1,460) g were analysed. The 50th centile of cFTOE at minute 2, 5, 10, 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.