title: Quantification of concentration changes in neonatal human cerebral oxidized cytochrome oxidase.
abstract: The oxygenation of cerebral cytochrome oxidase in vivo was investigated in eight newborn preterm infants. Near-infrared spectroscopy was used to quantify changes in the concentration of oxidized cytochrome oxidase ([CytO2]) observed during alterations in arterial oxygen saturation (SaO2) in the range of 85-99% and of carbon dioxide tension (PaCO2) in the range of 4.3-9.6 kPa. No relation was found between changes in SaO2 and [CytO2]. Alterations in PaCO2 were positively related both to changes in [CytO2] and total cerebral hemoglobin concentration [( Hb]t). The changes in [CytO2] ranged from 0.09 to 0.33 (median 0.21) mumol.l-1.kPa-1. The ratio [CytO2]/[Hb]t ranged from 0.06 to 0.12 (median 0.08). The relation of delta [CytO2] to the change in cerebral blood volume (delta CBV) was calculated: delta [CytO2]/delta CBV ranged from 0.09 to 0.18 (median 0.11) mumol/ml. These results define a fraction of cerebral cytochrome oxidase in the newborn infant that is oxidized after an increase in PaCO2 but demonstrate that a change in SaO2 in the range studied was not sufficient by itself to change [CytO2]. They differ from results of studies in adults; this may reflect significant differences between adult and neonatal brain.
authors.affiliation: Department of Paediatrics, University College and Middlesex School of Medicine, London, United Kingdom.
authors.forename: A D
authors.initials: AD
authors.lastname: Edwards
authors.forename: G C
authors.initials: GC
authors.lastname: Brown
authors.forename: M
authors.initials: M
authors.lastname: Cope
authors.forename: J S
authors.initials: JS
authors.lastname: Wyatt
authors.forename: D C
authors.initials: DC
authors.lastname: McCormick
authors.forename: S C
authors.initials: SC
authors.lastname: Roth
authors.forename: D T
authors.initials: DT
authors.lastname: Delpy
authors.forename: E O
authors.initials: EO
authors.lastname: Reynolds
mesh_terms: D001921:Brain / Q000201:enzymology*; D002245:Carbon Dioxide / Q000097:blood; D002560:Cerebrovascular Circulation; D003576:Electron Transport Complex IV / Q000378:metabolism*; D005260:Female; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D008297:Male; D010084:Oxidation-Reduction; D010100:Oxygen / Q000097:blood; D013055:Spectrophotometry, Infrared
chemical_list: D006454:Hemoglobins; D002245:Carbon Dioxide; D003576:Electron Transport Complex IV; D010100:Oxygen