Background: Familiarity with different methods and medications in anesthesia and producing sufficient depth of anesthesia are very important in anesthesia practice. Due to the central analgesic and sedative effect of lidocaine in the presence of the sufficient blood level, it can be used for general anesthesia. This study was carried out to compare the effect of halothane with lidocaine infusion on BIS during maintenance of anesthesia.

Materials and Methods: In this randomized double-blind controlled clinical trial, 66 patients scheduled for elective inguinal herniorrahaphy were randomized into two equal groups. For maintenance, one group received halothane (1%) with O2-N2O and another group received lidocaine infusion (100 &mug/kg/min). BIS was checked every 5 minutes for half an hour. Statistical analysis of data was done by Chi-square and T-test through SPSS software. P-values less than 0.05 were considered meaningful.

Results: Mean of BIS was 65.72 in the lidocaine group and 56.7 in the halothane group during the first 30 minutes. There was a significant statistical difference between the two groups (p<0.05).

Conclusion: Mean of BIS in lidocaine group was higher than that in the halothane group. If this indicates the presence of a light level of anesthesia, increasing the dose of hypnotics and opioids leads to an increase in the depth of anesthesia. However, since there is not any device for monitoring the effect of opioids on the central nervous system and the level of anesthesia, simultaneous monitoring of BIS and hemodynamic parameters seems to be a more reasonable idea.