Effect of bispectral index on intraoperative awareness under total intravenous anesthesia

Objective To investigate the incidence of intraoperative awareness using bispectral index(BIS) monitoring and evaluate the preventive effect of BIS on intraoperative awareness under total intravenous anesthesia.Methods 300 patients undergoing total intravenous anesthesia with BIS monitoring were randomly divided into two groups:group A and group B(n=150).In group A,the depth of anesthesia was regulated lower than 60 according to BIS.While in group B,the BIS monitor was covered and the depth of anesthesia was modulated according to the experience of the anesthesiologist.The BIS values were recorded at the time of anesthesia induction,beginning of operation,anesthesia withdrawal,end of operation,recovery of anesthesia and extubation.Results The basic BIS and BIS values at the time of anesthesia induction,awake and extubation had no significant differences between two groups(P0.05).The BIS values at the time of beginning of operation,anesthesia maintenance and anesthesia withdrawl in group B were significantly higher that those in group A(P0.05).The patients with awareness and suspected of awareness were not found in group A.The patients with awareness were not found in group B but there were two patients suspected of awareness.The incidence of patients suspected of awareness had significant difference between two groups(P0.05).Conclusion BIS monitoring during total intravenous anesthesia could maintain the appropriate depth of anesthesia and prevent intraoperative awareness.