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Bispectral Index ( BIS )Monitoring in Patients Undergoing Abstract code: 1316 Authors: N. Hemmati; A. Zokaei, M. Niazi, R. Parsapoor Address: Kermanshah Medical University Background: Bispectral index (BIS) is a monitor of anesthetic depth wherein complex EEG patterns are reduced to simple numbers in the range of 100 to 0. BIS decreases with increase in depth of anesthesia and adequate anesthesia levels are supposedly achieved with BIS levels of 40–60. The clinical usefulness of BIS, particularly during cardiac surgery is controversial and inadequately addressed. Methods: This study aims to study, in patients(CABG) the influence of deep anesthesia (BIS 40 range 35–45) on haemodynamics, oxygenation, use of additional vasodilators, time to extubation, adequacy of anesthesia (awareness) and costs of the whole procedure. These are compared with similar observations during normal levels of anesthesia (BIS 50, range 4055).Fourthy patients undergoing first time elective CABG with cardiopulmonary bypass (CPB) were randomized into 2 groups. In group BIS 40 (20 patient) higher levels of midazolam, sufentanil and pancuronium were chosen for induction and sufentanil infusion was kept at1.5–2 μg/ Kg/h to achieve the target levels of 35-45. In comparison, lower doses of all drugs including sufentanil infusion of 0.5–1.5 μg/ Kg/h was used in the BIS-50 (20 patient), group to achieve a target BIS of 45-55. In both groups, additional sufentanil, midazolam and propofol were used as reserve medication. Haemodynamic parameters studied were, heart rate (HR), mean arterial pressure (MAP),central venous pressures(CVP), cardiac output (CO) with NICO and mixed venous oxygen saturation (SVO2). Derived parameters were calculated using standard formulae. Arterial and mixed venous blood analysis was used to calculate the indices of oxygen delivery and consumption.BIS was measured at the frontal lobe of the dominant hemisphere and electrodes were replaced whenever electrode impedence increased. Data were recorded at 6 different time points, during awake state, under steady state anesthesia, after sternotomy, during and after CPB and at the end of surgery. Severe haemodynamic variations were managed by fluids, dobutamine, norepinephrine, epinephrine,and nitroglycerin. All patients were ventilated postoperatively till stability was achieved and time to extubation was documented. A standardized questionnaire was used on the third postoperative day to measure explicit intraoperative recall. Total cost of the anaesthetic drugs and BIS electrodes used was calculated. Results: The results of the study showed no significant difference between the 2 groups with regard to haemodynamics, SVO2, indices of oxygen delivery and consumption, need for dobutamine or nitroglycerin, levels of patient satisfaction and time to extubation. No sign of intraoperative memory was seen in either group. The BIS 50 group received significantly lesser anesthetic drugs , which saved significant money. Conclusions: Replacement of BIS electrodes with ECG electrodes for the same quality of monitoring has been recommended to reduce the cost. The authors in this study conclude, that varying the depth of anesthesia with the help of BIS in CABG patients did not influence most of the parameters studied. BIS guided reduction of anaesthetic medication is possible without explicit intraoperative recall, but the overall cost of BIS monitoring overrides the reduced drug costs.Authors recommended the use of BIS monitoring for deep hypothermia and total cardiac arrest during and after cardiac surgery to manage cerebral complications .