title: The effect of remifentanil on propofol requirements to achieve loss of response to command vs. loss of response to pain.
abstract: When providing total intravenous anaesthesia, careful selection of end-points is required in titrating dose to effect during induction. Although propofol and remifentanil have predominantly different pharmacodynamic effects, they are seen to interact in achieving loss of consciousness and analgesia. To highlight these differences, we performed a double-blind, randomised controlled trial, comparing one group of patients receiving propofol alone (n = 42) with another group receiving remifentanil plus propofol (n = 46) as a target-controlled infusion of remifentanil (Minto; 3 ng.ml-1). Propofol was also titrated using a target-controlled infusion (Marsh effect model) to produce loss of response to tactile and vocal stimuli, and subsequently to loss of response to pain. The effect-site concentration of propofol at which 50% of patients lost tactile/verbal response was 2.9 μg.ml-1in the propofol only group and 2.4 μg.ml-1in the remifentanil with propofol group. In contrast, loss of pain response occurred at 4.4 μg.ml-1in the propofol group, and 2.7 μg.ml-1in the remifentanil with propofol group, with correspondingly lower bispectral index values. Judicious use of analgesia in total intravenous anaesthesia can have a propofol-sparing effect and potentially minimise the suppression of brain electrical activity. .
authors.affiliation: Department of Anaesthesiology, University of Hong Kong, Hong Kong.
authors.forename: H B
authors.initials: HB
authors.lastname: Scott
authors.affiliation: Department of Anaesthesiology, University of Hong Kong, Hong Kong.
authors.forename: S W
authors.initials: SW
authors.lastname: Choi
authors.affiliation: Department of Anaesthesiology, University of Hong Kong, Hong Kong.
authors.forename: G T C
authors.initials: GT
authors.lastname: Wong
authors.affiliation: Department of Anaesthesiology, University of Hong Kong, Hong Kong.
authors.forename: M G
authors.initials: MG
authors.lastname: Irwin
mesh_terms: D000328:Adult; D000368:Aged; D000701:Analgesics, Opioid / Q000008:administration & dosage*; D000771:Anesthesia, Intravenous / Q000379:methods*; D018686:Anesthetics, Intravenous / Q000008:administration & dosage*; D003243:Consciousness / Q000187:drug effects; D056805:Consciousness Monitors; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004569:Electroencephalography / Q000187:drug effects; D005260:Female; D006801:Humans; D007260:Infusion Pumps; D008297:Male; D008875:Middle Aged; D010146:Pain / Q000188:drug therapy; D015742:Propofol / Q000008:administration & dosage*; D000077208:Remifentanil / Q000008:administration & dosage*
chemical_list: D000701:Analgesics, Opioid; D018686:Anesthetics, Intravenous; D000077208:Remifentanil; D015742:Propofol
keywords: bispectral index (BIS); pain; propofol; remifentanil; total intravenous anaesthesia (TIVA)