Monitoring depth of anesthesia based on complexity of electroencephalogram

Monitoring the depth of anesthesia is significant for the clinical surgery. In order to detect the depth of anesthesia (DOA), the Lempel-Ziv complexity (C(n)) analysis of electroencephalogram (EEG) of the SD rats was studied in this paper. The EEG C(n)s from different channels under different DOA were measured, and the relationship between C(n) and DOA was analyzed. The studies show that the C(n) of different channels changing with DOA have similar tendency, so it is enough to monitor DOA by one channel EEG analysis. The C(n) of EEG decreases while the depth of anesthesia increases and vice versa, it works very well in tracking rats´ depth and trend of anesthesia. Two thresholds of C(n) were defined; one distinguishes awake and light anesthesia state, the other distinguishes light and deep anesthesia state. In addition, the C(n) computation is simple and fast, therefore, it may provide a practical index to monitor DOA in real-time for clinic.