Comparison of Bispectra Index (BIS) and AEPEX Monitoring Systems in Coronary Bypass Surgery

Background Spontaneous recall of events during general anesthesia is called awareness. Awareness during the operation is common in coronary artery bypass grafting (CABG), especially in urgent cases and in patients with unstable hemodynamic condition before the operation. A standard method for the measurement of the depth of anesthesia (DoA) has not yet been introduced. A variety of techniques have been used for monitoring DoA like electroencephalography (EEG), monitoring muscle movement in the distal esophagus, and new methods of auditory evoked potentials (AEPs) and bispectra index (BIS). Recently, a more sensitive method, called aepEX which is a modified form of AEPs, has been used for the monitoring and controlling of DoA. This study was designed to compare the sensitivity of the aepEX system with the BIS system for DoA monitoring using current clinical and paraclinical methods. Methods In this prospective, controlled trial, 36 patients who were candidates for CABG were enrolled in the study. All the patients underwent a standard induction method for anesthesia with remifentanil, atracurium, and midazolam. Before anesthesia, both aepEX and BIS monitoring systems were controlled simultaneously in each patient. These systems had no effect on each other. Finally, all data about DoA, clinical data of awareness including BP, tear secretion, hemodynamic information, and demographic characteristics were collected and analyzed. Results This study compared the monitoring techniques for DoA, BIS, and aepEX. Results of this study were diagrams for the comparison of BIS and aepEX in different stages during CABG. According to these diagrams, essential analysis could be done about the quality of these two systems in DoA. Conclusions Our data demonstrated that the aepEX monitoring system had greater sensitivity in all the stages of anesthesia compared to the BIS system.