Efficacy of dexmedetomidine combined with nicardipine for controlled hypotension in patients undergoing orthopedic surgery

Objective To evaluate the efficacy of dexmedetomidine combined with nicardipine for controlled hypotension in patients undergoing orthopedic surgery.Methods Sixty ASA Ⅰ or Ⅱ patients,aged 32-64 yr,weighing 45-76 kg,scheduled for orthopedic surgery under general anesthesia,were randomly allocated into 2 groups (n =30 each):nicardipine group (group N) and dexmedetomidine + nicardipine group (group DN).A loading dose of dexmedetomidine 1 μg/kg was injected intravenously 10 min before induction of anesthesia,followed by infusion at 0.5.μg ·kg-1 ·h-1 until 30 min before the end of operation in group DN.While the equal volume of normal saline was given in group N.BIS value was maintained at 40-49 during operation.Controlled hypotension was performed with iv infusion of nicardipine at a rate of 2.5 μg· kg-1 · min-1,MAP was reduced to 60-65 mm Hg,then the infusion rate was adjusted to maintain MAP at this level,and nicardipine infusion was stopped while closing the skin.The amount of anesthetics and nicardipine consumed,blood loss,volume of fluid infused,and allogeneic blood transfusion during operation and the operation time,emergence time and extubation time were recorded.Results No patient received allogeneic blood transfusion in both groups.Compared with group N,the amount of anesthetics and nicardipine consumed was significantly decreased,the emergence time and extubation time were significantly shortened (P ＜ 0.05),and no significant change in the volume of fluid infused and blood loss was found in group DN (P ＞ 0.05).Conclusion Dexmedetomidine combined with nicardipine can reduce the requirements for nicardipine and anesthetics during operation,shorten the time for recovery from anesthesia and improve the efficacy of nicardipine for controlled hypotension when used for controlled hypotension in patients undergoing orthopedic surgery. Key words: Dexmedetomidine ;  Nicardipine ;  Hypotension, controlled