The effects of dexmedetomidine on hemodynamics and myocardial reperfusion injury in patients undergoing cardiac valve replacement surgery

Objective To investigate the effects of dexmedetomdine infusion on blood pressure, heart rate and myocardial reperfusion injury in patients undergoing cardiac valve replacement surgery. Methods Thirty patients(ASA ⅡorⅢ),aged 18-65yrs,undergoing cardiac vavle replacement surgery were randomized into 2groups(n=15each):control group(group C)and dexmedetomidine group(group D).Anesthesia was induced with midazolam(0.05mg/kg),sufentanyl(1μg/kg),etomidate(0.3mg/kg)and rocuronium(0.6mg/kg)in both groups.In group D,a 0.5μg/kg bolus dose of dexmedetomidine was administered 10min after the induction of anesthesia,followed by a 0.5μg· kg-1·h-1 infusion until the end of operation,while in group C equal volume of normal saline was infused instead of dexmedetomidine.HR and MAP were recorded before dexmedetomidine was administered(T0),after bolus dexmedetomidine was administered(T1),after surgical incision(T2),poststernotomy(T3),before CPB(T4),after CPB(T5)and at the end of operation(T6).Venous blood samples were taken at T0,T5,T6,at 6h(T7)and 24h(T8)after operation for measurement of serum concentration of H-FABP,CK-MB and cTnI by ELISA.Results MAP was significantly higher at T1than T0in group D(P0.05),while in group C MAP was significantly higher at T2and T3than T0(P0.05),and was higher than group D at T3.H-FABP,CK-MB and cTnI were significantly higher at T5,T6,6hand 24hafter operation than T0in both groups.Compared with group C,H-FABP were significantly lower at T5-T8after operation,and CK-MB and cTnI were significantly lower at 6h and 24hafter operation in group D(P0.05).Conclusion Dexmedetomidine 0.5μg/kg bolus followed by 0.5μg·kg-1·h-1 infusion during operation can maintain hemodynamics more stable and protect myocardium from reperfusion injury in patients undergoing cardiac valve replacement surgery.