Protective Effect Of Dexmedetomidine On Perioperative Myocardial Protection In Patients Undergoing Coronary Artery Bypass Grafting Under Low - Temperature Cardiopulmonary Bypass

BACKGROUDDexmedetomidine is a new highly selective, intravenous alpha-2 agonist with many desirable effects, including anxiolysis, analgesia, sedation, anaesthetic-sparing and perioperative muti-organ protection effects. It has been widely used in the world now. On-pump CABG carries 2 relatively low but well-recognized risks:the use of CPB and perioperative myocardial oxygen supply and demand imbalance lead to myocardial injury. Dexmedetomidine can decrease the heart rate, blood pressure, reduce the myocardial oxygen consumption, which may be beneficial to haemodynamics stable and reducing the incidents of myocardial ischemia. Tracheal intubation, skin incision and sternotomy are the important steps in CABG surgery, which increase the sympathetic activity and catecholamine release. They both lead to heart rate and blood pressure rising, which may increase the events of perioperative myocardial ischemia and myocardial infarction. Dexmedetomidine inhibit myocardial cell sympathetic activity and reduce systemic epinephrine and norepinephrine release, which positively affect myocardial oxygen supply and demand and provide myocardial protection. The aim of this study is to observe the impact of dexmedetomidine on perioperative myocardial injury in patients undergoing on-pump coronary artery bypass grafting(CABG) in a randomized, double-blind, placebo-controlled, prospective study.OBJECTThe aim of this study is to observe the effect of dexmedetomidine on perioperative myocardial protection and postoperative recovery in patients after on-pump coronary artery bypass grafting(CABG) in a randomized, double-blind, placebo-controlled, prospective study.METHODEighty patients who were undergoing on-pump CABG surgery were randomly divided into dexmedetomidine and control groups (groups A and C, respectively). After central venous catheter (CVC) inserted, in group A, dexmedetomidine infusion was started by a loading dose of 4ug·kg-1·h-1 for 15 minutes, followed by a continuous infusion of 0.7 ug·kg-1·h-1 during the operation. Group C received the same volume saline. Anesthesia was induced with 0.2-0.3 mg/kg of etomidate,0.02-0.05 mg/kg of midazolam,0.5-0.6mg/kg of rocuronium,2.5-3.0 ug/kg of sufentanil, and was maintained with 0.5-1.0ug/ml target controlled infusion(TCI) propofol,0.12 mg/kg/h Cisatracurium, and 1-1.5 ug/kg sufentanil each at the skin incision, beginning of CPB, end of CPB and closing thoracic cavity. The HR, SBP, DBP and vasoactive drugs were recorded at the time points of room enter(To), induction of anesthesia(T1), skin incision(T2), the termination of CPB(T3) and the end of surgery(T4). Blood was sampled for CK-MB, CTnT, norepinephrine and epinephrine at T1, T2, T3, T4,6 h post-surgery(T5) and 24 h post-surgery(T6). The awake time, extubation time, ICU stay time, hospitalization time after surgery, LVEF on the fifth day after surgery and the hospitalization cost were recorded.RESULTAt T3-T6, the CK-MB, CTnT and epinephrine level were much higher than those at T1 and T2 in the two groups (P<0.05). In group A, norepinephrine level decreased at T3-T5(P<0.05), and rose promptly at T5(P<0.05). At T3-T6, the CK-MB and cTnT level in group A were significantly lower than those in group C (P<0.05). At T3-T5, the norepinephrine and epinephrine level were much lower than those in group C (P<0.05). The awake time and extubation time in group D was much shorter than those in group P (P<0.05). There were no statistically significant differences for ICU stay time and hospitalization time (p>0.05). Before surgery, there was no statistically difference for LVEF between two groups. In group P, LVEF on the fifth day after surgery was much lower than that before surgery (P<0.05). No statistically difference was observed in group D. there was no difference for hospitalization cost between two groups. There were no severe adverse events in both groups.CONCLUSIONDexmedetomidine reduced perioperative myocardial injury and reduced the awake time and extubation time in patients undergoing on-pump coronary artery bypass grafting.