Comparison of BIS values at loss of consciousness induced by etomidate and propofol given by target-controlled infusion

Abstract

Objective To compare the bispectral index (BIS) values at loss of consciousness induced by etomidate and propofol given by target-controlled infusion (TCI). Methods A total of 120 American Society of Anesthesiologists physical status Ⅰ-Ⅲ patients, aged 18-64 yr, scheduled for elective carotid endartrectomy under total intravenous anesthesia, were divided into R0e, R1e, R2e, R0p, R1p and R2p groups (n=20 each) using a random number table method.R1e and R1p groups received remifentanil at an target effect-site concentration (Ce) of 1 ng/ml, and R2e and R2p groups received remifentanil at an target Ce of 2 ng/ml.At the beginning of anesthesia induction, remifentanil was given by TCI until the preset effect-site concentration was achieved, and etomidate was given by TCI at an initial target plasma concentration of 0.6 μg/ml followed by an increase by 0.1 μg/ml every minute until loss of consciousness in R0e, R1e and R2e groups, and propofol was given by TCI at an initial target plasma concentration of 2 μg/ml followed by an increase by 0.1 μg/ml every minute until loss of consciousness in R0p, R1p and R2p groups.BIS values were recorded immediately after pasting the BIS electrode, when the preset Ce of remifentanil was achieved and at loss of consciousness. Results Compared with group R0p, BIS values were significantly decreased at loss of consciousness in group R0e (P<0.05). Compared with group R1p, BIS values were significantly decreased at loss of consciousness in group R1e (P<0.05). BIS values were significantly lower at loss of consciousness in group R2e than in group R2p (P<0.05). Conclusion BIS values are significantly lower at loss of consciousness induced by TCI of etomidate than propofol. Key words: Etomidate; Propofol; Unconsciousness