【Objective】This prospective

randomized

double-blind study was designed to assess whether intraoperative infusion of dexmedetomidine can reduce the dosage of propofol

the time of extubation and opening eyes and make hemodynamic more smooth in extubation. Parameters are received in adult patients undergoing major abdominal surgery with total intravenous anesthesia. 【Methods】 Nighty patients were randomly assigned to three groups. Group T1 (n = 30) received a loading dose of dexmedetomidine 0.5 mg·kg-1 iv during 15 minutes

followed by a continuous infusion at a rate of 0.5 μg·kg-1·h-1 throughout the operation. Group T2 (n = 30) received a loading dose of dexmedetomidine 0.5 mg ?滋kg-1 iv during 15 minutes

followed by a continuous infusion at a rate of 0.25 μg·kg-1·h-1 throughout the operation. Group C(n = 30) received a volume-matched bolus and infusion of placebo (0.9% saline). The Ce values of propofol in induction

the intraoperative total amount of propofol

the recovery time from stopping propofol or remifentanil to extubation

the time from stopping remifentanil to open eyes

and the hemodynamic in extubation were recorded.【Results】 The induction doses of propofol in group T1 [effect site concentrations:(1.5 ± 0.8)μg/mL] and group T2 [effect site concentrations: (1.6 ± 0.5)μg/mL] were significantly lower than that in group C [effect site concentrations: (2.2 ± 0.9) μg/mL

P<0.05]. In addition

the effect site concentrations of propofol at every intraoperative observation points in group T1 and T2 were significantly lower than those in group C (P < 0.05). The total dose of propofol was significantly different (P < 0.05)

(1399.7 ± 410.5) mg in group C

(1312.1 ± 627.3) mg in group T1 and (1048.0 ± 461.0)mg in group T2. The time from stopping infused propofol (TSP) [group C:(26.5 ± 8.8)min; group T1:(36.0 ± 12.8)min; group T2:(33.0 ± 7.6)min)] and from stopping remifentanil (TSR) to extubation [group C:(12.4 ± 7.4) min; group T1: [(17.1 ± 9.9) min; group T2: (16.0 ± 7.9) min] were not significantly different (P > 0.05). The time to opening eye in group T1 [(22.1 ± 9.5) min] and T2 [(37.2 ± 7.3)min] were significantly longer than that in control group [(13.1 ± 4.8)min

P < 0.05]. The blood pressure and heart rate were more stable in group T1 and T2 than in control group during anesthesia recovery period. 【Conclusion】 Continuous iv dexmedetomidine during abdominal surgery decreased the requirements of propofol in induction and every intraoperative observation points and the dose of propofol reduced about 25%. Dexmedetomidine did not affect the time of tracheal extubation but prolong the time of opening eyes. The hemodynamic parameters were more stable during anesthesia recovery period when dexmedetomidine was co-administrated.