Monitoring of Hypnosis State During General Anesthesia With Propofol by Patient State Index From SEDLine®

Introduction:

There is a large intra-and interindividual variability in the effect of propofol. To deal with this problem, a real-time monitoring and therefore a more accurate titration of anesthetic agents is proposed. Brain function monitors based on a processed analysis of EEG (Electroencephalogram) can help to control pharmacodynamic effects of hypnotic agents. PSI values provide a measurement of the hypnotic effect of propofol. It will be observed an inverse correlation between the propofol infusion rate and the PSI value.

Objectives:

To design a computer program to record simultaneously the propofol infusion rate, PSI and Electromyogram (EMG).

To study the correlation between PSI values obtained from the SEDLine® monitor and the infusion rate of propofol during general anesthesia.

To obtain a mathematical model of the system from data recorded with different identification techniques.

Methods:

A group of patients scheduled for surgery under a standard total intravenous anesthesia (TIVA) with propofol and remifentanil will be recruited. The hypnotic effect of propofol will be monitored with the PSI from a SEDline monitor continuously. All anesthetic doses and their changes fall within conventional dosing.

The procedure for recording data and obtaining the pharmacokinetics/pharmacodynamics (PK / PD) model will be connecting a SEDLine® monitor to a laptop with an original program developed by members of our team. The program automatically stores the infusion rate of propofol (mg/kg/h) and the simultaneous values of PSI and frontal EMG. Graphics and data collected will be explored with various systems of techniques for pattern recognition in order to get the best fit to define a mathematical model of the dose of propofol and PSI values. A subsequent computer analysis with MATLAB® will estimate the correlation between the infusion of propofol infusion rate and PSI values.

Inclusion criteria

• American Society of Anesthesiologists classification of I, II, or III
• Patient signed an informed consent

Exclusion criteria

• Patients with prior neurological disease, epilepsy or stroke.
• Patients who are receiving drug therapy that may alter processed EEG monitoring and decrease the PSI accuracy.
• American Society of Anesthesiologists classification IV or higher