Propofol Effect-Site Target Controlled Infusion in the Obese: Characterization of the Time Profile of Bispectral Index Response
The aim of this study is to characterize the Pharmacokinetic/Pharmacodynamic relationship of a single bolus dose of propofol in obese patients and to extract a time to peak effect (t-peak) from the estimated model parameters.
|Study Design:||Endpoint Classification: Pharmacokinetics/Dynamics Study
Intervention Model: Single Group Assignment
Masking: Open Label
Primary Purpose: Supportive Care
|Official Title:||Propofol Effect-Site Target Controlled Infusion in the Obese: Characterization of the Time Profile of Bispectral Index Response.|
- Profile of Pharmacokinetic and Pharmacodynamic of an induction bolus dose of propofol in obese patients. [ Time Frame: 1, 2, 3, 5, 7 and 10 minutes after the initial bolus dose or until BIS > 75 ] [ Designated as safety issue: No ]
Pharmacokinetic parameters (V1, V2, V3, CL, Q)
Pharmacodynamic parameters (E0, Emax, C50, Gamma, t1/2Ke0, T peak )
|Study Start Date:||April 2011|
|Study Completion Date:||November 2011|
|Primary Completion Date:||November 2011 (Final data collection date for primary outcome measure)|
14 obese patients(IMC>35 kg m-2) scheduled for laparoscopic bariatric surgery
Propofol was administered by plasma TCI and a bolus dose was given by setting the initial plasma target between 12-16 μg/ml according to the anesthesiologist criteria. The protocol target range was selected based on previous experience using this model in the obese. After the patients reached this target, propofol infusion was stopped until the patients woke up (BIS>75). No other drugs were given during this period. Facemask ventilation was assisted only if necessary to maintain SpO2 > 90%. BIS data and propofol infusion data were automatically recorded every five seconds using the AnestFusor© program. Arterial blood samples of 4 ml for propofol assays were collected at 1, 2, 3, 5, 7 and 10 minutes after the initial bolus dose or until BIS > 75. After the patient woke up the study was considered finished and propofol infusion was restarted according to the anesthesiologist plan.
Target controlled infusion (TCI) is a technique to administer intravenous drugs that allows rapid achievement and maintenance of predetermined drug concentrations, either in plasma (Cp) or at the site of effect (Ce).
To characterize the time profile of propofol effect an additional parameter, the equilibration half time between plasma and effect site (T1/2keo) needs to be incorporated in the pharmacokinetic (PK) model.