Patent ID: 6016444
Filing Date: 2000-01-18
Classification: A61B,A61M,Y10S

Abstract:
An electroencephalograph (EEG) method using a computer system for controlling anesthesia to a patient undergoing a medical procedure, comprising:(a) removably connecting a set of at least two EEG electrodes to the scalp of the patient, at least one EEG electrode at the front of the scalp and at least one other electrode at the back of the scalp, and administering sufficient anesthesia to the patient for the patient to attain the plane of anesthesia selected by an operator;(b) amplifying and digitizing the ongoing brain waves of the patient after the patient is anesthetized and before being operated upon and computing power spectrum to provide an initial set of covariance matrices which are self-norm digital data representing a comparison of EEG power in at least one selected frequency band at a frontal EEG electrode with EEG power in the same band at a posterior EEG electrode and recording this initial set of covariance matrices or the average across the set in computer system memory;(c) computing the covariance matrix of features extracted from selected EEG electrodes;(d) during the operation, digitizing the ongoing brain waves at the same EEG electrodes and extracting the same measures to provide a current set of covariance matrices for the selected measures at the selected EEG electrodes;(e) in the computer system, statistically comparing the initial and subsequent sets of univariate digital data and coherence matrices to specify univariate and multivariate distances between the initial set and the current set;(f) providing a control signal if the comparison of (e) indicates that the patient is emerging from his fully anesthetized state;(g) automatically, in response to the control signal, adjusting the anesthesia administered to the patient during the operation in response to the control signal to restore the patient to the selected plane of anesthesia.