Estimation of propofol plasma-effect site equilibration rate constant (keO) with the cerebral state index.

Pablo Sepulveda MD†, Luis I. Cortínez MD*, Gastón Núñez MD†, Alejandro Recart MD†

†Clinica Alemana-Universidad del Desarrollo, *Pontificia Universidad Católica de Chile

 

Running Head:

Propofol ke0 has not been calculated using the CSI (CSM, Danmeter) as a measure of its hypnotic effect.

 

Abstract

Background:

A biophase model combining Marsh kinetics and a time to peak effect of 1.6 min (ke0= 1.21 min-1) have shown to accurately predict the time course of propofol effect measured with BIS. (1) Since all EEG derived indices have their own time delays these values do not necessarily characterize the dynamic profile of a different monitor. (2) The Cerebral State Monitor (CSM) is a new device based on a fuzzy logic analysis of the EEG. The aim of this study is to calculate the ke0 of propofol using the CSI as the measure of its hypnotic effect.

 

Methods:

After routine non-invasive monitoring of arterial pressure, electrocardiogram, pulse oximetry, and consciousness (CSM) ten healthy adult volunteers, aged 21-44 yr, received a bolus dose of propofol 1.8 mg kg-1 at a rate of 1200 ml hr-1. The CSI response was automatically recorded every 1 second using the CSM software and a laptop until CSI spontaneously returned to basal values. The complete response curve of CSI was then used to calculate propofol, ke0 using a non-parametric “loop-collapsing” method. The pharmacokinetic model published by Marsh was used to predict the plasma concentrations of propofol after the bolus dose in each patient. Values are median (range).

 

Results:

All patients completed the study. The propofol ke0 estimated was 1.27 (0.6 - 1.95) min-1.

 

Conclusions:

The Propofol ke0 estimated with the CSM was similar to the value previously validated with the BIS monitor.

 

1.             Struys M. Anesthesiology 2000; 92:399-420.

2.             Pilge S. Anesthesiology 2006;104:488-94.