Objective To analyze the correlation of the autoregressive model with exogenous input extracted
auditory evoked potentials
index (AAI),
bispectral index (BIS) with propofol-induced sedation. Methods Twenty ASAⅠ-Ⅱ adult patients undergoing elective gynecological surgery under lumbar epidural anesthesia and CESA were randomly studied. When operation started, propofol 6-8 mg/(kg·h) was perfused until the score level 1 observer's assessment of the alertness/sedation scale (OAA/S) reached. AAI and BIS were monitored on different OAA/S score levels and their correlation with propofol induced sedation was analyzed. Results AAI and BIS were distinctly reduced as patients OAA/S scores were decreased, and had a signficnat correlation with sedation (during the onset phase, the coefficients of Spearman's rank correlation r=0 933, 0 533, P =0 01; during the recovery phase r=0 943, 0 592, P =0 000). There was signficnat difference in coefficient between AAI and BIS during the onset and recovery phase ( P <0 01). Conclusion AAI and BIS correlated well with propofol-induced sedation quantitatively and accurately.