title: Effects of medetomidine and ketamine on the regional cerebral blood flow in cats: a SPECT study.
abstract: Brain perfusion can be investigated using single photon emission computed tomography (SPECT) and the intravenous injection of (99m)technetium ethyl cysteinate dimer ((99m)Tc-ECD). However, sedation using medetomidine, an α(2)-agonist, or anaesthesia using medetomidine and ketamine, an N-methyl-d-aspartate-(NMDA)-antagonist, may be required for SPECT studies in cats but can affect the regional cerebral blood flow (rCBF). The effects of medetomidine, with or without ketamine, on regional brain perfusion were therefore investigated in six cats under three conditions. Injection of tracer occurred before sedation or anaesthesia (condition A), following intramuscular (IM) sedation with medetomidine (condition M) or after IM anaesthesia with medetomidine and ketamine (condition MK). Medetomidine and medetomidine with ketamine caused a significantly higher total tracer uptake in all brain regions. Semi-quantification of brain perfusion gave lower perfusion indices in several sub-cortical regions in conditions M and MK, compared to A. Left-right differences were observed in the temporal cortex (A), the temporal, parietal cortex and the thalamus (M) and the frontal cortex (MK). A significantly higher perfusion index in the sub-cortical regions, compared to the whole cortex, was only present in condition A. This study showed that caution is needed when quantifying brain perfusion indices when using sedative or anaesthetic agents that may affect rCBF.
authors.affiliation: Department of Medicine and Clinical Biology of Small Animals, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium. tim.waelbers@ugent.be
authors.forename: T
authors.initials: T
authors.lastname: Waelbers
authors.forename: K
authors.initials: K
authors.lastname: Peremans
authors.forename: S
authors.initials: S
authors.lastname: Vermeire
authors.forename: K
authors.initials: K
authors.lastname: Piron
authors.forename: M
authors.initials: M
authors.lastname: Doom
authors.forename: V O
authors.initials: VO
authors.lastname: Boer
authors.forename: H
authors.initials: H
authors.lastname: de Leeuw
authors.forename: M A D
authors.initials: MA
authors.lastname: Vente
authors.forename: A
authors.initials: A
authors.lastname: Dobbeleir
authors.forename: I
authors.initials: I
authors.lastname: Gielen
authors.forename: K
authors.initials: K
authors.lastname: Audenaert
authors.forename: I
authors.initials: I
authors.lastname: Polis
mesh_terms: D000778:Anesthetics, Dissociative / Q000008:administration & dosage*; D000818:Animals; D001776:Blood Circulation Time / Q000662:veterinary; D002415:Cats / Q000378:metabolism*; D002560:Cerebrovascular Circulation / Q000187:drug effects*; D018592:Cross-Over Studies; D003545:Cysteine / Q000031:analogs & derivatives; D004338:Drug Combinations; D005260:Female; D006993:Hypnotics and Sedatives / Q000008:administration & dosage*; D007273:Injections, Intramuscular / Q000662:veterinary; D007275:Injections, Intravenous / Q000662:veterinary; D007649:Ketamine / Q000008:administration & dosage*; D008279:Magnetic Resonance Imaging / Q000662:veterinary; D020926:Medetomidine / Q000008:administration & dosage*; D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; D015899:Tomography, Emission-Computed, Single-Photon / Q000662:veterinary
chemical_list: D000778:Anesthetics, Dissociative; D004338:Drug Combinations; D006993:Hypnotics and Sedatives; D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; D007649:Ketamine; C059659:technetium Tc 99m bicisate; D003545:Cysteine; D020926:Medetomidine