Effect of BIS monitoring on sevoflurane consumption in patients undergoing breast cancer surgeries under general anesthesia—a prospective observational study

Abstract Background The bispectoral index (BIS), a parameter derived from electroencephalogram, has been used to assess the depth of anesthesia. The objectives of this study were to evaluate the effect of BIS monitoring on sevoflurane consumption and recovery profile at the end of anesthesia. After obtaining Institutional Review Board approval and written informed consent, 25 American Society of Anesthesiologists (ASA) physical status classification 1 and 2 patients undergoing breast cancer surgeries who had BIS monitoring in addition to standard ASA monitoring (BIS GROUP) were compared against 25 controls (control group). In the control group, adequate depth of anesthesia was maintained using routine clinical parameters like heart rate (HR), mean arterial pressure (MAP), and minimum alveolar concentration (MAC) of sevoflurane, while in the BIS group, it was maintained by keeping the BIS score between 40 and 60 (mean 50). Data including demographics, sevoflurane consumption, hemodynamic variables, and recovery profile at the end of anesthesia was assessed in terms of time for eye opening (TEO), time for motor response (TMR), time for extubation (TE), and modified Aldrete scoring (MAS). Results The mean sevoflurane consumption was lower ( P = 0.019) in the BIS group. TEO ( P = 0.001), TMR ( P = 0.0001), and TE (0.003) were shorter in the BIS group. Difference in MAS between the 2 groups was not statistically significant ( P = 0.085). Conclusions BIS monitoring during anesthesia resulted in significant reduction in the sevoflurane consumption. Patients who had BIS monitoring awoke earlier and had better recovery profile at the end of anesthesia.