Prevalence of awareness under general anaesthesia guided by cerebral state index

Awareness under general anaesthesia can have some complications for the patients which might be very dangerous. One of the major operations in which awareness are very prevalent is Caesarean section. Because there is no objective methods to assess this complication, using cerebral state index (CSI) for decreasing the complications in caesarean sections has been studied in this paper. In this clinical trial study, 290 pregnant women, 20-40 years old with normal body mass index, and ASA classification 1 or 2 after taking written consent were enrolled to this study. During the anaesthesia, cerebral state index was maintained between 40 and 60 when possible ant it was recorded at different stages of anesthesia. Induction of anaesthesia was provided by sodium thiopental 5 mg/kg and succinylcholine 1.5 mg/kg and maintenance of anaesthesia provided with N2O: O2 in 50% concentration, midazolam 0.02 mg/kg, morphine 0.1 mg/kg, fentanyl 2μg/kg and propofol to maintain CSI between 40-60. For evaluation of awareness modified Brice questionnaire and for statistical analysis T-test or Chi-square test was used. 7 out of 270 patients had dreams after being awakened, but none of them were related to the events in the operating theatre. Prevalence of awareness in this study correlated with other studies in which awareness was least 3%, but less than some studies in which it was about 6-10%. Cerebral state index could decrease awareness during anaesthesia, but in this study, its use was not able to completely eliminate it.