title: The effects of xenon anesthesia on the relationship between cerebral glucose metabolism and blood flow in healthy subjects: a positron emission tomography study.
abstract: BACKGROUND
  General anesthetics can alter the relationship between regional cerebral glucose metabolism (rCMR(glc)) and blood flow (rCBF). In this positron emission tomography study, our aim was to assess both rCMR(glc) and rCBF in the same individuals during xenon anesthesia.
  
  
  METHODS
  (18)F-labeled fluorodeoxyglucose and (15)O-labeled water were used to determine rCMR(glc) and rCBF, respectively, in five healthy male subjects at baseline (awake) and during 1 minimum alveolar anesthetic concentration of xenon. Anesthesia was based solely on xenon. Changes in rCMR(glc) and rCBF were quantified using region-of-interest and voxel-based analyses.
  
  
  RESULTS
  The mean (sd) xenon concentration during anesthesia was 67.2 (0.8)%. Xenon anesthesia induced a uniform reduction in rCMR(glc), whereas rCBF decreased in 7 of 13 brain regions. The mean decreases in the gray matter were 32.4 (4.0)% (P < 0.001) and 14.8 (5.9)% (P = 0.007) for rCMR(glc) and rCBF, respectively. rCMR(glc) decreased by 10.9 (6.4)% in the white matter (P = 0.030), whereas rCBF increased by 9.2 (7.3)% (P = 0.049). The rCBF/rCMR(glc) ratio was especially increased in the insula, anterior and posterior cingulate, and in the somatosensory cortex.
  
  
  CONCLUSIONS
  In general, the magnitude of the decreases in rCMR(glc) during 1 minimum alveolar anesthetic concentration xenon anesthesia exceeded the reductions in rCBF. As a result, the ratio between rCMR(glc) and rCBF was shifted to a higher level. Interestingly, xenon-induced changes in cerebral metabolism and blood flow resemble those induced by volatile anesthetics.
authors.affiliation: Turku PET Centre, University of Turku, Finland. ruut.laitio@tyks.fi
authors.forename: Ruut M
authors.initials: RM
authors.lastname: Laitio
authors.forename: Jaakko W
authors.initials: JW
authors.lastname: Långsjö
authors.forename: Sargo
authors.initials: S
authors.lastname: Aalto
authors.forename: Kaike K
authors.initials: KK
authors.lastname: Kaisti
authors.forename: Elina
authors.initials: E
authors.lastname: Salmi
authors.forename: Anu
authors.initials: A
authors.lastname: Maksimow
authors.forename: Riku
authors.initials: R
authors.lastname: Aantaa
authors.forename: Vesa
authors.initials: V
authors.lastname: Oikonen
authors.forename: Tapio
authors.initials: T
authors.lastname: Viljanen
authors.forename: Riitta
authors.initials: R
authors.lastname: Parkkola
authors.forename: Harry
authors.initials: H
authors.lastname: Scheinin
mesh_terms: D000328:Adult; D000764:Anesthesia, Closed-Circuit; D000769:Anesthesia, Inhalation; D018685:Anesthetics, Inhalation; D001786:Blood Glucose / Q000378:metabolism; D001921:Brain / Q000000981:diagnostic imaging*; D001923:Brain Chemistry / Q000187:drug effects*; D002560:Cerebrovascular Circulation / Q000187:drug effects*; D019788:Fluorodeoxyglucose F18; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D012121:Respiration, Artificial; D014978:Xenon; D055815:Young Adult
chemical_list: D018685:Anesthetics, Inhalation; D001786:Blood Glucose; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D014978:Xenon; D005947:Glucose