Monitor-decoupled pharmacodymamics of propofol in children using State Entropy as the clinical end point.

This paper presents two alternative approaches to characterize the pharmacodynamics of propofol anesthesia in children, using State Entropy as a clinical end point. The first approach is the traditional approach where the pharmacodynamic model is described in terms of an effect-site equilibration rate constant and the Hill equation. In the second approach (the monitor-decoupled approach) the dynamics of the Entropy monitor is identified and added to the traditional pharmacodynamic model. The traditional approach resulted in mean k(e0) values of 2.08min(-1) and 1.27min(-1) for the Paedfusor and Kataria pharmacokinetic models, respectively. The monitor-decoupled approach resulted in significantly larger values (mean k(e0) values of 2.57min(-1) and 1.71min(-1)) than the traditional approach. The differences between k(e0) values suggest that the dynamic effect of the Entropy monitor must be accounted for when identifying the "true" pharmacodynamics of the patient, without the bias caused by the monitor's processing characteristics. The values of k(e0) obtained in this study were larger than those values previously published for the Bispectral Index. This is likely due to the different processing characteristics of the Entropy and Bispectral Index monitors, as well as the use of different pharmacokinetic models.