title: Precision and bias of target controlled propofol infusion for sedation.
abstract: BACKGROUND
  The purpose of this study is to test precision and systematic bias of a target controlled infusion (TCI) of propofol in human volunteers at two sedative concentrations.
  
  
  METHODS
  We studied the 'Diprifusor' model (Marsh Pharmacokinetics and a Graseby 3400 infusion pump) in 18 human volunteers at two sedative target plasma concentrations (0.5 and 1.0 microg ml(-1)). Twenty minutes after infusion start or change and 20 min after discontinuation of the infusion plasma propofol concentrations were measured using liquid chromatography-mass spectroscopy (LC-MS). Plasma propofol concentrations were compared with concentrations predicted by the TCI system. Agreement of those two measures (precision and bias) was determined using regression analysis.
  
  
  RESULTS
  We found little systematic bias but poor precision. When setting the TCI system to deliver a plasma concentration of 1.0 microg ml(-1) one can predict the actual plasma concentration with 95% confidence only within a range of 0.44-1.38 microg ml(-1).
  
  
  CONCLUSIONS
  This finding helps to explain differences in responses to propofol sedation; pharmacokinetic variability appears to be an important factor.
authors.affiliation: Department of Anesthesiology, University of Florida Colleges of Medicine and Engineering, Gainesville, Florida, USA. froelich@uab.edu
authors.forename: M A
authors.initials: MA
authors.lastname: Frölich
authors.forename: D M
authors.initials: DM
authors.lastname: Dennis
authors.forename: J A
authors.initials: JA
authors.lastname: Shuster
authors.forename: R J
authors.initials: RJ
authors.lastname: Melker
mesh_terms: D000328:Adult; D016292:Procedural Sedation / Q000379:methods*; D004334:Drug Administration Schedule; D016503:Drug Delivery Systems; D004360:Drug Therapy, Computer-Assisted / Q000379:methods; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D006993:Hypnotics and Sedatives / Q000008:administration & dosage* / Q000097:blood; D007260:Infusion Pumps; D007262:Infusions, Intravenous; D016014:Linear Models; D008297:Male; D015742:Propofol / Q000008:administration & dosage* / Q000097:blood
chemical_list: D006993:Hypnotics and Sedatives; D015742:Propofol