Performance of a Propofol Pharmacokinetic Model for Target-Controlled infusion in Morbidly Obese Japanese Patients
*Takeshi Umegaki Department Of Anesthesiology, Osaka, Japan
*Corresponding Author: Takeshi Umegaki
Department Of Anesthesiology, Osaka, Japan Email:email@example.com
Published on: 2018-11-02
Study Objectives: To evaluate the accuracy of target-controlled infusion (TCI) of propofol based on total body weight (TBW) in severely obese patients using the Marsh pharmacokinetic model. Design: Prospective study. Setting: A large tertiary care teaching hospital. Patients: Severely obese (body mass index ≥35) adult patients who underwent scheduled surgery between April 1, 2014 and March 31, 2015. Interventions: None. Measurements Propofol was administered to patients during surgery using the ‘Diprifusor’ TCI system to maintain a bispectral index of 40 to 60. TBW was used to calculate blood propofol concentration (μg/ml). The median performance error (MDPE) and median absolute performance error (MDAPE) were calculated to examine the difference between the calculated and measured blood propofol concentrations. We obtained 39 sampling points from 13 patients (Six orthopedic surgery patients, five general surgery patients, and two neurosurgery patients) for analysis.
Propofol; Target-Controlled Infusion; Severe Obesity
The Marsh model is a popular pharmacokinetic model for the target-controlled infusion (TCI) of propofol, and incorporates the use of a ‘Diprifusor’ system that includes pharmacokinetic parameters. This model was based on the pharmacokinetics of propofol determined by Gepts and colleagues. In another study, White and Kenny analyzed 33 adult surgical patients to demonstrate the usability of a three-compartment mathematical model, and also established the appropriate ranges of blood propofol concentration for anesthesia induction and maintenance. While these studies form the foundation of the Marsh model, the reported patient characteristics of the study sample in Gepts et al. indicate that few, if any, of the patients had a BMI that exceeded 35. Although the Marsh model stipulates the use of body weight as a standard, there is a need to assess the validity of this model in obese patients.