A comparison of hemodynamic effects of etomidate-midazolam and ketamine-midazolam for anesthesia induction in coronary artery bypass grafting

Hemodynamic stability is the primary goal of anesthetic management during coronary artery bypass grafting (CABG). The stable hemodynamic profile of etomidate makes this drug the agent of choice for anesthesia induction during CABG. However, the undesirable effect of etomidate on steroid synthesis in adrenal glands has given rise to the search for an appropriate alternative for anesthesia induction during CABG. The aims of this study were to compare the effects of anesthesia induction with ketamine midazolam or etomidate-midazolam combinations on hemodynamic parameters and adrenal suppression in CABG. After Ethics Committee approval and patients' written consent were obtained, 40 adult patients undergoing CABG were randomly allocated into two groups for this prospective randomized double-blinded study. Anesthesia was induced with ketamine 1 mg/kg in ketamine group (n = 20) and with etomidate 0.3 mg/kg in etomidate group. All patients also received midazolam 0.025 mg/kg during anesthesia induction. Standard opioid-based anesthesia maintenance, cardiopulmonary bypass (CPB), and surgical technique were used in all patients. Intra- and postoperative hemodynamic parameters including systolic, diastolic, and mean arterial pressures and heart rate were recorded. In order to investigate the etomidate induced adrenal suppression blood cortisol levels were measured before anesthesia, 5 minutes after anesthesia induction, and during rewarming (at 35°C). In addition, at postoperative days 1 and 4 adrenocorticotropic hormone (ACTH) stimulation tests were performed. The groups were not significantly different in terms of demographic features except for a higher number of females in ketamine group than etomidate group (9/11 vs 1/19, p= 0.04). This difference was due to the randomization. Intra- and postoperative hemodynamic parameters were not significantly different between the groups (p>0.05). However, compared with their matching baseline values, the systolic, diastolic, and mean arterial pressures significantly decreased in both groups (p<0.05). Despite similar baseline measurements, V cortisol levels were significantly higher 5 minutes after induction, during rewarming, and after ACTH stimulation test at postoperative day 1 in group ketamine than group etmidate (p<0.05). Cortisol levels were similar in both groups after postoperative day 4 ACTH stimulation test (p>0.05). The groups were not significantly different in terms of duration of surgery, intraoperative inotropic/vasopressor use, intraoperative use of fluids and blood products, duration of postoperative ventilation, frequency of postoperative delirium, and intensive care unit and hospital lengths of stay (p>0.05). In conclusion, ketamine-midazolam combination is an acceptable alternative to etomidate midazolam combination in terms of hemodynamic stability. Compared with ketamine midazolam combination, etomidate-midazolam combination significantly decreased cortisol levels during the intraoperative and early postoperative periods.