A method and apparatus to monitor the neurologic state of a patient
undergoing general anesthesia is provided. Previous automated systems to
monitor the neurologic state of a patient undergoing general anesthesia
involve a significant time delay between the patient's true hypnotic
state and the computed indices. The present invention reduces this time
delay by using a different analysis technique applied to spontaneous EEG.
A wavelet decomposition and statistical analysis of the observed EEG is
conducted and compared to reference data to provide a numerical
indicator. In addition, this indicator is more consistent with the
patient's loss of consciousness indicated by the loss of count event than
previous systems.