The effect of dexmedetomidine on hemodynamics and stress reaction in patients undergoing cardiac valve replacement surgery

Objective To evaluate the effect of dexmedetomidine on hemodynamies and stress reaction in patients undergoing cardiac valve replacement surgery.Methods Twenty four patients undergoing cardiac valve replacement surgery were allocated randomly into study group ( group A,n =12 ) and control group ( group B,n =12).Dexmedetomidine [ 0.5 μg/kg bolus and infusion at a rate of 0.5 μg/(kg·h)] was administered to patients in study group. Heart rate(HR),mean arterial pressure (MAP),central venous pressure (CVP),cardiac output (CO),cardiac index (CI),stroke volume (SV),stroke volume index (SVI) and bispectral index (BIS) were recorded before administration of dexmedetomidine (T0 ),5 minutes after administration of dexmedetomidine ( T1 ),10 minutes after administration of dexmedetomidine (T2 ),1 minute after tracheal intubation (T3 ),iminute after sternal saw ( T4 ),15 minutes after the termination of cardiopulmonary bypass (CPB) ( T5 ) and at the end of operation ( T6 ).Serum cortisol,blood glucose and blood lactate concentration were measured at T0,T3,T4,T5 and T6.Results MAP,HR and BIS were significantly lower in group A compared those of group B at T1,T2 (P ＜ 0.05).MAP,HR were significantly higher in group B compared those of group A at T3,T4 ( P ＜0.05 ).HR,CO,CI were significantly lower in group A compared those of group B at T5,T6 ( P ＜ 0.05 ).Serum cortisol,blood glucose and blood lactate concentration were significantly increased at T5 and T6 compared those at T0 in both groups ( P ＜ 0.01 ).Serum cortisol concentration was ( 19.4 ± 4.9 ) μg/dl,( 19.8 ±4.6) μg/dl at T5,T6 in group A,Serum cortisol concentration was (25.4 ±5.1 ) μg/dl,(24.2 ±5.3) μg/dl at T5,T6 in group B,Serum cortisol concentration was significantly lower in group A compared that of group B at T5,T6 ( P ＜ 0.05 ).Blood glucose concentration was significantly lower in group A compared that of group B at T6 ( P ＜ 0.05).Conclusion Dexmedetomidine can reduce sympathetic nervous over excitement and stress reaction and maintain hemodynamic stability in cardiac surgery. Key words: Dexmedetomidine;  Cardiac surgery;  Hemodynamics;  Stress reaction