title: Correlation of EEG spectral entropy with regional cerebral blood flow during sevoflurane and propofol anaesthesia.
abstract: ENTROPY index monitoring, based on spectral entropy of the electroencephalogram, is a promising new method to measure the depth of anaesthesia. We examined the association between spectral entropy and regional cerebral blood flow in healthy subjects anaesthetised with 2%, 3% and 4% end-expiratory concentrations of sevoflurane and 7.6, 12.5 and 19.0 microg.ml(-1) plasma drug concentrations of propofol. Spectral entropy from the frequency band 0.8-32 Hz was calculated and cerebral blood flow assessed using positron emission tomography and [(15)O]-labelled water at baseline and at each anaesthesia level. Both drugs induced significant reductions in spectral entropy and cortical and global cerebral blood flow. Midfrontal-central spectral entropy was associated with individual frontal and whole brain blood flow values across all conditions, suggesting that this novel measure of anaesthetic depth can depict global changes in neuronal activity induced by the drugs. The cortical areas of the most significant associations were remarkably similar for both drugs.
authors.affiliation: Turku PET Centre and Department of Pharmacology and Clinical Pharmacology, University of Turku, Turku, Finland.
authors.forename: A
authors.initials: A
authors.lastname: Maksimow
authors.forename: K
authors.initials: K
authors.lastname: Kaisti
authors.forename: S
authors.initials: S
authors.lastname: Aalto
authors.forename: M
authors.initials: M
authors.lastname: Mäenpää
authors.forename: S
authors.initials: S
authors.lastname: Jääskeläinen
authors.forename: S
authors.initials: S
authors.lastname: Hinkka
authors.forename: S
authors.initials: S
authors.lastname: Martens
authors.forename: M
authors.initials: M
authors.lastname: Särkelä
authors.forename: H
authors.initials: H
authors.lastname: Viertiö-Oja
authors.forename: H
authors.initials: H
authors.lastname: Scheinin
mesh_terms: D000328:Adult; D018685:Anesthetics, Inhalation / Q000494:pharmacology; D018686:Anesthetics, Intravenous / Q000494:pharmacology; D001921:Brain / Q000000981:diagnostic imaging; D002560:Cerebrovascular Circulation / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004569:Electroencephalography / Q000187:drug effects*; D019277:Entropy; D006801:Humans; D008297:Male; D008738:Methyl Ethers / Q000494:pharmacology*; D016343:Monitoring, Intraoperative / Q000379:methods*; D049268:Positron-Emission Tomography; D015742:Propofol / Q000494:pharmacology*; D000077149:Sevoflurane
chemical_list: D018685:Anesthetics, Inhalation; D018686:Anesthetics, Intravenous; D008738:Methyl Ethers; D000077149:Sevoflurane; D015742:Propofol