Improving Information Extraction From EEG on Cerebral Anesthetic Drug Effects

Patient State Index (PSI-1) is a processed EEG parameter that quantifies the level of EEG inhibition. A new algorithm (PSI-2) has been created to improve performance in low power EEG. PSI is unitless. It ranges between 100 and 0 (100 representing 'awake state', 0 denoting 'no detectable electrical brain activity'). PSI-1 and PSI-2 were compared in their correlation with measured propofol and sevoflurane concentrations with or without remifentanil (0, 2 ,or 4 ng/mL) via several estimated PD model parameters. In the data table, BL (Baseline) denotes PSI-2 measurements when no drug is present; Emax denotes PSI in the presence of the maximum drug effect; C50 is the drug concentration which produces 50% of the maximal drug effect (ug/mL for Propofol C50, vol% for Sevoflurane C50).

Patient State Index (PSI-1) is a processed EEG parameter that quantifies the level of EEG inhibition. A new algorithm (PSI-2) has been created to improve performance in low power EEG. PSI is unitless. It ranges between 100 and 0 (100 representing 'awake state', 0 denoting 'no detectable electrical brain activity'). PSI-1 and PSI-2 were compared in their correlation with measured propofol and sevoflurane concentrations with or without remifentanil (0, 2 ,or 4 ng/mL) via several estimated PD model parameters. In the data table, BL (Baseline) denotes PSI-2 measurements when no drug is present; Emax denotes PSI in the presence of the maximum drug effect; C50 is the drug concentration which produces 50% of the maximal drug effect (ug/mL for Propofol C50, vol% for Sevoflurane C50).

Patient State Index (PSI-1) is a processed EEG parameter that quantifies the level of EEG inhibition. A new algorithm (PSI-2) has been created to improve performance in low power EEG. PSI is unitless. It ranges between 100 and 0 (100 representing 'awake state', 0 denoting 'no detectable electrical brain activity'). PSI-1 and PSI-2 were compared in their correlation with measured propofol and sevoflurane concentrations with or without remifentanil (0, 2 ,or 4 ng/mL) via several estimated PD model parameters. In the data table, BL (Baseline) denotes PSI-2 measurements when no drug is present; Emax denotes PSI in the presence of the maximum drug effect; C50 is the drug concentration which produces 50% of the maximal drug effect (ug/mL for Propofol C50, vol% for Sevoflurane C50).

For all study groups (i.e. P, S, PR, and SR), the estimated PD model parameters that represent remifentanil interactions are Theta1 and Theta2, which are unit-less values. Theta1 and Theta2 are zero for all volunteers not receiving remifentanil. In case an interaction between remifentanil and propofol or sevoflurane exists, the estimate for Theta1 will be significantly different from zero. If the interaction in the 4 ng/mL group exceeds the estimated interaction for the 2 ng/mL group, Theta2 will be significantly higher than zero.