title: The influence of hyperoxia on regional cerebral blood flow (rCBF), regional cerebral blood volume (rCBV) and cerebral blood flow velocity in the middle cerebral artery (CBFVMCA) in human volunteers.
abstract: Conflicting results reported on the effects of hyperoxia on cerebral hemodynamics have been attributed mainly to methodical and species differences. In the present study contrast-enhanced magnetic resonance imaging (MRI) perfusion measurement was used to analyze the influence of hyperoxia (fraction of inspired oxygen (FiO2) = 1.0) on regional cerebral blood flow (rCBF) and regional cerebral blood volume (rCBV) in awake, normoventilating volunteers (n = 19). Furthermore, the experiment was repeated in 20 volunteers for transcranial Doppler sonography (TCD) measurement of cerebral blood flow velocity in the middle cerebral artery (CBFV(MCA)). When compared to normoxia (FiO2 = 0.21), hyperoxia heterogeneously influenced rCBV (4.95 +/- 0.02 to 12.87 +/- 0.08 mL/100g (FiO2 = 0.21) vs. 4.50 +/- 0.02 to 13.09 +/- 0.09 mL/100g (FiO2 = 1.0). In contrast, hyperoxia diminished rCBF in all regions (68.08 +/- 0.38 to 199.58 +/- 1.58 mL/100g/min (FiO2 = 0.21) vs. 58.63 +/- 0.32 to 175.16 +/- 1.51 mL/100g/min (FiO2 = 1.0)) except in parietal and left frontal gray matter. CBFV(MCA) remained unchanged regardless of the inspired oxygen fraction (62 +/- 9 cm/s (FiO2 = 0.21) vs. 64 +/- 8 cm/s (FiO2 = 1.0)). Finding CBFV(MCA) unchanged during hyperoxia is consistent with the present study's unchanged rCBF in parietal and left frontal gray matter. In these fronto-parietal regions predominantly fed by the middle cerebral artery, the vasoconstrictor effect of oxygen was probably counteracted by increased perfusion of foci of neuronal activity controlling general behavior and arousal.
authors.affiliation: Department of Anaesthesia and Intensive Care Medicine, University of Innsbruck, Innsbruck, Austria. christian.kolbitsch@uibk.ac.at
authors.forename: Christian
authors.initials: C
authors.lastname: Kolbitsch
authors.forename: Ingo H
authors.initials: IH
authors.lastname: Lorenz
authors.forename: Christoph
authors.initials: C
authors.lastname: Hörmann
authors.forename: Martin
authors.initials: M
authors.lastname: Hinteregger
authors.forename: Alexander
authors.initials: A
authors.lastname: Löckinger
authors.forename: Patrizia L
authors.initials: PL
authors.lastname: Moser
authors.forename: Christian
authors.initials: C
authors.lastname: Kremser
authors.forename: Michael
authors.initials: M
authors.lastname: Schocke
authors.forename: Stephan
authors.initials: S
authors.lastname: Felber
authors.forename: Karl P
authors.initials: KP
authors.lastname: Pfeiffer
authors.forename: Arnulf
authors.initials: A
authors.lastname: Benzer
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity; D001810:Blood Volume; D003287:Contrast Media; D017352:Echo-Planar Imaging; D006801:Humans; D018496:Hyperoxia; D008297:Male; D020768:Middle Cerebral Artery / Q000502:physiology*; D018709:Statistics, Nonparametric; D017585:Ultrasonography, Doppler, Transcranial
chemical_list: D003287:Contrast Media