The effects of xenon anesthesia on the relationship between cerebral glucose metabolism and blood flow in healthy subjects: a positron emission tomography study.
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.
Laitio
Ruut M
RM
Turku PET Centre, University of Turku, Finland. ruut.laitio@tyks.fi
Långsjö
Jaakko W
JW
Aalto
Sargo
S
Kaisti
Kaike K
KK
Salmi
Elina
E
Maksimow
Anu
A
Aantaa
Riku
R
Oikonen
Vesa
V
Viljanen
Tapio
T
Parkkola
Riitta
R
Scheinin
Harry
H
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
D018685:Anesthetics, Inhalation; D001786:Blood Glucose; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D014978:Xenon; D005947:Glucose