title: A novel technique to determine an 'apparent ke0 ' value for use with the Marsh pharmacokinetic model for propofol.
abstract: Debate continues over the most appropriate blood-brain equilibration rate constant (ke0) for use with the Marsh pharmacokinetic model for propofol. We aimed to define the optimal ke0 value. Sixty-four patients were sedated with incremental increases in effect-site target concentration of propofol while using six different ke0 values within the range 0.2-1.2 min(-1). Depth of sedation was assessed by measuring visual reaction time. A median 'apparent ke0' value of 0.61 min(-1) (95% CI 0.37-0.78 min(-1)) led to the greatest probability of achieving a stable clinical effect when the effect-site target was fixed at the effect-site concentration displayed by the target-controlled infusion system, at the time when a desired depth of sedation had been reached. By utilising a clinically relevant endpoint to derive this value, inter-individual pharmacokinetic and pharmacodynamic variability may be accounted for.
authors.affiliation: Royal Infirmary of Edinburgh, Edinburgh, UK.
authors.forename: A J
authors.initials: AJ
authors.lastname: Thomson
authors.forename: A F
authors.initials: AF
authors.lastname: Nimmo
authors.forename: F H M
authors.initials: FH
authors.lastname: Engbers
authors.forename: J B
authors.initials: JB
authors.lastname: Glen
mesh_terms: D000328:Adult; D000368:Aged; D018686:Anesthetics, Intravenous / Q000493:pharmacokinetics*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D015742:Propofol / Q000493:pharmacokinetics*; D055815:Young Adult
chemical_list: D018686:Anesthetics, Intravenous; D015742:Propofol