title: Argon does not affect cerebral circulation or metabolism in male humans.
abstract: OBJECTIVE
  Accumulating data have recently underlined argon´s neuroprotective potential. However, to the best of our knowledge, no data are available on the cerebrovascular effects of argon (Ar) in humans. We hypothesized that argon inhalation does not affect mean blood flow velocity of the middle cerebral artery (Vmca), cerebral flow index (FI), zero flow pressure (ZFP), effective cerebral perfusion pressure (CPPe), resistance area product (RAP) and the arterio-jugular venous content differences of oxygen (AJVDO2), glucose (AJVDG), and lactate (AJVDL) in anesthetized patients.
  
  
  METHODS
  In a secondary analysis of an earlier controlled cross-over trial we compared parameters of the cerebral circulation under 15 minutes exposure to 70%Ar/30%O2 versus 70%N2/30%O2 in 29 male patients under fentanyl-midazolam anaesthesia before coronary surgery. Vmca was measured by transcranial Doppler sonography. ZFP and RAP were estimated by linear regression analysis of pressure-flow velocity relationships of the middle cerebral artery. CPPe was calculated as the difference between mean arterial pressure and ZFP. AJVDO2, AJVDG and AJVDL were calculated as the differences in contents between arterial and jugular-venous blood of oxygen, glucose, and lactate. Statistical analysis was done by t-tests and ANOVA.
  
  
  RESULTS
  Mechanical ventilation with 70% Ar did not cause any significant changes in mean arterial pressure, Vmca, FI, ZFP, CPPe, RAP, AJVDO2, AJVDG, and AJVDL.
  
  
  CONCLUSIONS
  Short-term inhalation of 70% Ar does not affect global cerebral circulation or metabolism in male humans under general anaesthesia.
authors.affiliation: Department of Anaesthesiology, Erasmus University Medical Centre, Rotterdam, The Netherlands.
authors.forename: Frank
authors.identifier: http://orcid.org/0000-0001-5693-3721
authors.initials: F
authors.lastname: Grüne
authors.affiliation: Centre of Anaesthesiology, Critical Care, Emergency Medicine and Pain Therapy (ZARI), University-Hospital of Göttingen, Göttingen, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Kazmaier
authors.affiliation: Department of Anaesthesiology, Erasmus University Medical Centre, Rotterdam, The Netherlands.
authors.forename: Sanne Elisabeth
authors.initials: SE
authors.lastname: Hoeks
authors.affiliation: Department of Anaesthesiology, Erasmus University Medical Centre, Rotterdam, The Netherlands.
authors.forename: Robert Jan
authors.initials: RJ
authors.lastname: Stolker
authors.affiliation: Department of Anaesthesiology, University Hospital RWTH Aachen, Aachen, Germany.
authors.forename: Marc
authors.initials: M
authors.lastname: Coburn
authors.affiliation: Department of Anaesthesiology, Critical Care, Emergency Medicine and Pain Therapy, Klinikum Oldenburg, Medical Campus University of Oldenburg, Oldenburg, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Weyland
mesh_terms: D000328:Adult; D000368:Aged; D000768:Anesthesia, General; D001128:Argon / Q000494:pharmacology*; D001783:Blood Flow Velocity / Q000187:drug effects*; D002560:Cerebrovascular Circulation / Q000187:drug effects / Q000502:physiology*; D018592:Cross-Over Studies; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D019344:Lactic Acid / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D020768:Middle Cerebral Artery / Q000187:drug effects*; D010100:Oxygen / Q000378:metabolism; D011446:Prospective Studies
chemical_list: D019344:Lactic Acid; D001128:Argon; D005947:Glucose; D010100:Oxygen