Validation of a Pharmacokinetic Pharmacodynamic Model to Administer Propofol in Obese Patients
The purpose of this study is to validate an integrated pharmacokinetic-pharmacodynamic model to administer propofol in obese patients.
Our hypothesis is that pharmacokinetic and pharmacodynamic changes occur with increasing weight and that mathematical models to administer drugs in obese patients can be developed to accurately predict dose schemes in this population.
|Study Design:||Endpoint Classification: Pharmacokinetics/Dynamics Study
Intervention Model: Single Group Assignment
Masking: Open Label
Primary Purpose: Supportive Care
|Official Title:||Validation of a Pharmacokinetic Pharmacodynamic Model to Administer Propofol in Obese Patients|
- Validated pharmacokinetic-pharmacodynamic model of Propofol in Obese patients [ Time Frame: During the intraoperative period and until 120 min after stopping propofol infusion ] [ Designated as safety issue: No ]
|Study Start Date:||March 2012|
|Study Completion Date:||May 2012|
|Primary Completion Date:||April 2012 (Final data collection date for primary outcome measure)|
20 obese patients(IMC>35 kg m-2) scheduled for laparoscopic bariatric surgery.
General anesthesia will be induced administering propofol by effect site TCI system using our previously derived model, the target plasma concentration initially will be set at 4 mcg/ml. After loss of consciousness, rocuronium 0.6mg/kg, and remifentanil 0.2mcg/kg/min will be given to facilitate tracheal intubation. After intubation propofol target will be decreased to 3 for 10 minutes and then adapted to the needs of each patient to maintain stable BIS values between 40 and 50. At the end of surgery propofol infusion will be stopped, and patients will be transferred to the recovery unit extubated. Samples of 2.5 ml of arterial blood will be taken at 2, 5 and 10 min after every new target is set. Thereafter samples will be taken at 2, 5, 10, 15, 30, 60, 120 min after stopping drug infusion. Blood samples will be immediately centrifuged and then stored until analysis.
Propofol is the most frequently used IV anesthetic today. Propofol TCI is commonly used for induction and maintenance of general anaesthesia in obese and non obese patients. However, current propofol PK models, used in TCI devices, were derived from studies that did not include obese patients. A controversial issue for propofol dose adjustment in this population has been the selection of an adequate size descriptor to scale PK parameters, as drug administration based on total body weight can result in overdose, and conversely, administration based on ideal body weight can result in a sub-therapeutic dose. In a previous study from our group, we developed a PK model capable of characterizing the influence of obesity on propofol disposition. The purpose of this study is to validate this model to administer propofol in obese patients.
|Hospital Clinico Pontificia Universidad Catolica|
|Santiago, Region Metropolitana, Chile|
|Principal Investigator:||Luis I Cortínez, MD||Departamento de Anestesiología, Hospital Clínico Pontificia Universidad Católica de Chile|