Background: Unpleasant side effect of awareness within general anesthesia is potentially an important concern in patients. The patient may sleep during anesthesia and feels the pain due to loss of pain suppression of sensory perception of pain during surgery. The aim of this study is to determine the effect of BIS monitoring on level of awareness during anesthesia in women undergoing elective caesarean section.

Materials and Methods: In this double-blind, randomized clinical trial, 214 ASAI–II patients, over 15 years of age, candidate for elective cesarean section were included in the study. Patients randomly divided to two groups of anesthesia with and without BIS monitoring. Patients were assessed for awareness within anesthesia immediately, 24 hours, and 3-6 days after operation.

Results: From 107 patients without BIS monitoring, 8 patients (7.4%) suffered from awareness during anesthesia and their awareness score was two and greater than two. While none of the patients in the BIS group experienced awareness during anesthesia. Level of awareness during anesthesia in the control group was significantly more than the BIS group (p<0.0000).

Conclusion: The incidence of awareness during anesthesia is significantly lower in BIS monitored group than the control group.