[Simulation analysis of estimated effect-site concentrations of propofol and fentanyl administered by a TCI system for other drugs]

Abstract

Background: We experienced a case of inadequate sedation because of inappropriate use of TCI system for fentanyl.

Methods: We evaluated the blood and effect-site concentrations of propofol and fentanyl calculated by a pharmacokinetic simulation model in which the administration of one drug was managed with target-controlled infusion pump set for another drug.

Results: In case propofol was administered with an effect-site-steering TCI system for fentanyl, the blood concentration of propofol increased within the first few minutes, especially immediately after starting the infusion, decreased for the next 10 minutes, and then was stabilized at a level of 0.7 times the target concentration. When fentanyl was administered with a blood-steering TCI for propofol, the calculated blood concentration of fentanyl was almost equal to the target concentration in the first few minutes, and then gradually increased until reaching 2.21 times the target concentration, at 240 minutes. Furthermore, the propofol concentration and the fentanyl concentration showed small differences between the target and calculated concentrations when the infusion time was not so long.

Conclusions: When the administration time is short, the anesthesiologist must be aware of the difficulty in distinguishing the human error of choosing one drug for the TCI system for another drug.