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Abstract

We would like to thank Schwaberger et al for their comments in relation to our delivery room (DR) study evaluating the effects of fractionated inspired oxygen on cerebral oxygenation in preterm infants. We recognize their expertise in this area and concur with their comments in relation to the potential effect of PaO2 on the cerebral vasculature during this period of adaptation. They have elegantly shown the alteration in cerebral blood volume that occurs over the first minutes of life, supporting the idea that postnatal increase in PaO2 results in cerebral vasoconstriction.1Schwaberger B. Pichler G. Binder-Heschl C. Baik N. Avian A. Urlesberger B. Transitional changes in cerebral blood volume at birth.Neonatology. 2015; 108: 253-258Crossref PubMed Scopus (24) Google Scholar However, the reactivity of the cerebral vessels and the physiological responses to other potential factors are difficult to tease out during this critical time period. In particular, carbon dioxide, a potent vasodilator, may have a significant role in altering cerebral blood flow at this time. We have recently shown that preterm infants with significant respiratory compromise requiring intubation generally have higher end-tidal CO2 values,2Hawkes G.A. Kenosi M. Finn D. O'Toole J.M. O'Halloran K.D. Boylan G.B. et al.Delivery room end tidal CO2 monitoring in preterm infants <32 weeks.Arch Dis Child Fetal Neonatal Ed. 2016; 101: 62-65PubMed Google Scholar and by default higher PaCO2 values. One would expect higher relative and absolute cerebral oxygen saturation (rSCO2) values in patients with higher carbon dioxide levels. In the absence of simultaneous measurements of PaCO2 and rSCO2, and alterations in both, it is difficult to draw any firm conclusions, other than to say that during adaptation, the influence of these competing variables warrants further evaluation. The assessment and monitoring of preterm infants in the DR remains quite subjective, and the only objective assessment method currently in common use is the pulse oximeter. Significant physiological changes occur in the premature infant during the immediate transition period following birth, generating large amounts of physiological data, which are currently not being recorded, let alone being interrogated. Easy-to-use, infant-specific, multimodal monitoring sensors are now available in addition to real-time data capture and analysis tools, making comprehensive, objective monitoring in the DR achievable even for the most premature infants. Because management in the first minutes of life has the potential to change the neonatal course of very preterm infants for better or for worse, it is our obligation, as a community of practitioners, to provide more objectivity to what exactly happens during these critical moments in the DR. Does cerebral vasoconstriction following delivery protect against hyperoxia?The Journal of PediatricsVol. 173PreviewWe read with interest the report by Kenosi et al.1 Our study group has shown that the requirement for respiratory support in preterm infants is associated with lower regional cerebral oxygenation compared with infants undergoing normal transition.2,3 Kenosi et al now add that preterm infants with respiratory support in need for higher fraction of inspired oxygen (FiO2) levels did not show an increase in cerebral hyperoxia, but had a higher degree of cerebral hypoxia. The authors suggest that these findings might be caused by changes in cerebral blood flow due to mechanisms of cerebral autoregulation. Full-Text PDF