Monitoring of Depth of Anesthesia Using Entropy Monitor in Off-pump Coronary Artery Bypass Graft Surgery: An Observational Study

To monitor the depth of anesthesia using entropy monitor during off-pump coronary bypass graft surgery and to assess memories or recall of intraoperative awareness using Modified Version of Brice Questionnaire after 48 hours of surgery. Materials and methods: It is a cross-sectional observational study. After approval by the institutional ethics committee, the study was conducted in 100 patients posted for cardiac surgery involving off-pump coronary bypass surgery fulfilling the inclusion criteria. After written valid consent, general anesthesia was given as per the protocol. Entropy indices are calculated and displayed in real-time. The indices were manually recorded at various cardiac events. Controlled mechanical ventilation was continued in the ICU. Tracheal extubation was performed when hemodynamic and respiratory parameters remained stable. All patients were interviewed 48 hours after surgery about any memories or recall of intraoperative awareness using the modified Brice questionnaire. Results: In our study, the hemodynamic parameters like pulse rate, systolic, and diastolic blood pressure were well maintained. Three patients reported awareness during the procedure. One of them had vivid dreams which the patient was not able to recall the nature of the dream and the other two patients who had woken up during the procedure heard some noises during the surgery. None of the patients reported being in pain when awake. Conclusion: An entropy monitor might aid off-pump coronary artery bypass graft surgery (OPCABG) in preventing intraoperative awareness and monitoring the depth of anesthesia. It also aids in reducing anesthetic dosage and hence avoids untoward side effects of anesthesia. Clinical significance: Our study suggested that the incidence of awareness is high during the OPCABG, hence modification in anesthesia technique is needed at present.