Precision and bias of target controlled propofol infusion for sedation

Br J Anaesth. 2005 Apr;94(4):434-7. doi: 10.1093/bja/aei081. Epub 2005 Jan 28.


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.

Publication types

  • Evaluation Study

MeSH terms

  • Adult
  • Conscious Sedation / methods*
  • Drug Administration Schedule
  • Drug Delivery Systems
  • Drug Therapy, Computer-Assisted / methods
  • Female
  • Gas Chromatography-Mass Spectrometry
  • Humans
  • Hypnotics and Sedatives / administration & dosage*
  • Hypnotics and Sedatives / blood
  • Infusion Pumps
  • Infusions, Intravenous
  • Linear Models
  • Male
  • Propofol / administration & dosage*
  • Propofol / blood


  • Hypnotics and Sedatives
  • Propofol