Application of EEG non-linear analysis in monitoring depth of anesthesia / 解放军医学杂志

ABSTRACT

Objective To investigate the changes in non-linear dynamics properties of EEG and the application of real-time monitoring of non-linear indexes during the course of general anesthesia. Methods EEG was recorded in 65 patients undergoing operations. They were randomly divided into five groups isoflurane, sevoflurane, desflurane (n=15, respectively), propofol 8mg/(kg?h) and propofol 10mg/(kg?h) (n=10, respectively). The EEG derived parameters correlation dimension (D 2 ) and approximate entropy (ApEn) non-linear indexes were calculated simultaneously during the whole operation, including the time of entering the operation room, anesthetic induction, intraoperation, recovery, and regaining consciousness. Results At the time of entering the operation room, their D 2 and ApEn nonlinear indexes appeared to be highest. Both the indexes decreased swiftly during anesthetic induction, and they dropped to lower values and leveled off during the intra-operation period. During recovery period, both of them rose gradually and returned to a high level in the post-operation awaking period. Conclusions Changes in the depth of anesthesia could be real-timely monitored and precisely measured with non-linear indexes of EEG. Non-linear dynamic analysis might provide us with more information on consciousness during general anesthesia