title: Reduction of cytochrome C oxidase during vasovagal hypoxia-ischemia in human adult brain: a case study.
abstract: Near-infrared spectroscopy (NIRS)-derived measurement of oxidized cytochrome c oxidase concentration ([oxCCO]) has been used as an assessment of the adequacy of cerebral oxygen delivery. We report a case in which a reduction in conscious level was associated with a reduction in [oxCCO]. Hypoxaemia was induced in a 31-year-old, healthy male subject as part of an ongoing clinical study. Midway through the hypoxaemic challenge, the subject experienced an unexpected vasovagal event with bradycardia, hypotension and reduced cerebral blood flow (middle cerebral artery blood flow velocity decrease from 70 to 30 cm s(-1)) that induced a brief reduction in conscious level. An associated decrease in [oxCCO] was observed at 35 mm (-1.6 μM) but only minimal change (-0.1 μM) at 20-mm source-detector separation. A change in optical scattering was observed, but path length remained unchanged. This unexpected physiological event provides an unusual example of a severe reduction in cerebral oxygen delivery and is the first report correlating change in clinical status with changes in [oxCCO].
authors.affiliation: Neurocritical Care Unit, University College Hospitals, WC1N 3BG, London, UK. arnab.ghosh@ucl.ac.uk.
authors.forename: Arnab
authors.initials: A
authors.lastname: Ghosh
authors.affiliation: Medical Physics & Bioengineering, University College London, WC1E 6BT, London, UK.
authors.forename: Christina
authors.initials: C
authors.lastname: Kolyva
authors.affiliation: Medical Physics & Bioengineering, University College London, WC1E 6BT, London, UK.
authors.forename: Ilias
authors.initials: I
authors.lastname: Tachtsidis
authors.affiliation: Neurocritical Care Unit, University College Hospitals, WC1N 3BG, London, UK.
authors.forename: David
authors.initials: D
authors.lastname: Highton
authors.affiliation: Medical Physics & Bioengineering, University College London, WC1E 6BT, London, UK.
authors.forename: Clare E
authors.initials: CE
authors.lastname: Elwell
authors.affiliation: Neurocritical Care Unit, University College Hospitals, WC1N 3BG, London, UK.|Medical Physics & Bioengineering, University College London, WC1E 6BT, London, UK.
authors.forename: Martin
authors.initials: M
authors.lastname: Smith
mesh_terms: D000328:Adult; D001919:Bradycardia / Q000378:metabolism; D001921:Brain / Q000098:blood supply* / Q000201:enzymology / Q000378:metabolism; D002560:Cerebrovascular Circulation / Q000502:physiology; D003576:Electron Transport Complex IV / Q000378:metabolism*; D006801:Humans; D000860:Hypoxia / Q000201:enzymology*; D007511:Ischemia / Q000378:metabolism / Q000503:physiopathology*; D008297:Male; D010100:Oxygen / Q000378:metabolism; D010455:Peptides / Q000378:metabolism; D019265:Spectroscopy, Near-Infrared / Q000379:methods
chemical_list: D010455:Peptides; C017422:hypotensin (snake); D003576:Electron Transport Complex IV; D010100:Oxygen