title: The effect of thiopental on cerebral blood flow, and its relation to plasma concentration, during simulated induction of anaesthesia in a porcine model.
abstract: The reversible effect of an induction dose of thiopental on the cerebral blood flow (CBF) was characterized by repeated 133Xe washout measurements during stable physiological conditions in anaesthetized pigs. A thiopental effect corresponding to induction of light and transient anaesthesia was confirmed by electroencephalography (EEG). The concentration (arterial plasma) -effect (-% CBF) relationship of thiopental was estimated using a sigmoidal Emax model. The injection caused a rapid 36 +/- 4.5% (mean +/- s.d.) drop in CBF, with return to baseline by 80 min. According to the pharmacodynamic model, the maximal effect of thiopental (Emax) in this experimental set-up was a 58% lowering of the CBF and the concentration at half-maximal effect (EC50) was 25 micrograms.ml-1. This study provides a complete characterization of the effect of thiopental on the CBF, including the time-course and concentration-effect relationship. A comparison to limited data in the literature suggests that the findings in the pigs constitute a fair approximation of the action of thiopental during the clinical induction of anaesthesia.
authors.affiliation: Department of Anaesthesia, University of Lund, Malmö General Hospital, Sweden.
authors.forename: S
authors.initials: S
authors.lastname: Björkman
authors.forename: F
authors.initials: F
authors.lastname: Nilsson
authors.forename: J
authors.initials: J
authors.lastname: Akeson
authors.forename: K
authors.initials: K
authors.lastname: Messeter
authors.forename: I
authors.initials: I
authors.lastname: Rosén
mesh_terms: D000771:Anesthesia, Intravenous; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002536:Cerebral Arteries / Q000187:drug effects; D002560:Cerebrovascular Circulation / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004569:Electroencephalography / Q000187:drug effects; D013552:Swine; D013874:Thiopental / Q000008:administration & dosage / Q000097:blood* / Q000494:pharmacology*; D013997:Time Factors; D014655:Vascular Resistance / Q000187:drug effects; D014980:Xenon Radioisotopes
chemical_list: D014980:Xenon Radioisotopes; D013874:Thiopental