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NEUROSURGICAL ANESTHESIOLOGY AND NEUROSCIENCE

The Effects of Xenon Anesthesia on the Relationship Between Cerebral Glucose Metabolism and Blood Flow in Healthy Subjects: A Positron Emission Tomography Study

Ruut M. Laitio, MD^*, Jaakko W. Långsjö, MD^*, Sargo Aalto, MSc^*, Kaike K. Kaisti, MD^*, Elina Salmi, MD^*, Anu Maksimow, MD^*, Riku Aantaa, MD, Vesa Oikonen, MSc^*, Tapio Viljanen, MSc^*, Riitta Parkkola, MD^||, and Harry Scheinin, MD^*

From the *Turku PET Centre, University of Turku; Departments of Anesthesiology and Intensive Care, Otorhinolaryngology, and ||Radiology, Turku University Hospital; and Department of Psychology, Åbo Akademi University, Turku, Finland.

Address correspondence to Ruut Laitio, MD, PhD, Department of Anesthesiology and Intensive Care, Turku University Hospital, POB 52, FIN-20521 Turku, Finland. Address e-mail to ruut.laitio{at}tyks.fi.

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: ¹⁸F-labeled fluorodeoxyglucose and ¹⁵O-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.