ABSTRACT
Off pump CABG is the most commonly performed cardiac surgical procedure involving multi vessel grafting through median sternotomy. Approach of lateral and posterior walls of heart for grafting, necessitates need for lifting or tilting heart producing elevated atrial pressures, fall in cardiac output and thus profound hypotension. Maintaining delicate balance between myocardial oxygen demand and supply is crucial to prevent myocardial insults and associated sequelae for which the mean arterial pressure is maintained >70 mmHg to facilitate adequate coronary perfusion pressure achieved by infusion of vasopressors like dobutamine and increased preload. Another strategy adopted by anaesthesiologist to limit this hypotension is by reducing isoflurane and thus cardiac surgical patients are prone for awareness. Awareness is the explicit recall of sensory perceptions during anaesthesia.METHODSWe studied 40 patients with ASA physical status II & III, between age group of 18 to 65 years scheduled for elective off pump CABG after institutional ethical committee clearance and written informed consent. Patients were randomly allocated into two groups of 20 each. Group 1 (isoflurane in oxygen given with BIS maintained at 55+/-5) and Group 2 (isoflurane in oxygen given without BIS).Comparison of the two groups was done in terms of gender, age, height, weight, heart rate, hemodynamics, dial concentration, minimum alveolar concentration, drugs consumed, time to extubation and intraoperative awareness. Results were statistically analyzed using independent t test, chi square test and Fischer exact test. Data was presented in terms of mean, median and standard deviation. The 'p' value of <0.05 was considered significant.RESULTSHeart rate, systolic blood pressure, diastolic blood pressure and mean arterial pressure were higher in Group 1 compared to Group 2. The dial concentration and minimum alveolar concentration were found to be statistically significant 5 minutes after intubation upto 4.5 hours of the cardiac surgical procedure with 'p' value <0.05. Amount of midazolam and propofol used in Group 1 was higher when compared to Group 2 while there was no statistical significance with use of opioid (fentanyl) or muscle relaxant (pancuronium). Time to extubation and intraoperative awareness were comparable between both the groups.CONCLUSIONSBIS monitoring reduces amount of isoflurane used along with the prevention of awareness in cardiac surgical patients. It helps not only the anaesthesiologist but also the other operation theatre personnel by preventing environmental pollution.