Pharmacokinetic/Hemodynamic Model for Propofol Concentration during Anesthesia

Abstract

Propofol is widely used for the induction and maintenance of anesthesia in surgical procedures. It is administered intravenously using TCI (Target Controlled Infusion) systems. Present systems use open loop control based on multicompartment models that are adapted based on subject’s physical parameters. This study presents a physiologically based pharmacokinetic-hemodynamic model designed to predict more accurately the changes in the concentration of the anesthetic in the body during different surgical scenarios. In addition to pharmacokinetics, the model considers hemodynamic aspects such as filtration and reabsorption of fluid between the blood and the extravascular compartment as well as changes in hematocrit levels, changes in hydrostatic and colloid osmotic pressures and changes in cardiac output due to fluid infusion and voiding. Model validation was performed using raw data from previously published researches that are available online. Simulations of the model show that specific scenarios of bleeding and fluid infusion can cause unexpected changes in Propofol concentration in the brain. These results demonstrate the importance of blood volume monitoring to obtain more accurate TCI systems