The Effect Of Different Doses Of Dexmedetomidine On The ECe50 Of Propofol During Hysteroscopy

Objective:To observe the effect of different doses of dexmedetomidine on the median effective chamber concentration(ECe50)of propofol during hysteroscopy.Methods:150 patients scheduled for hysteroscopic surgery,in the Affiliated Hospital of North Sichuang Medical College,were divided randomly into five groups and received a bolus of dexmedetomidine(0.4μg/kg,group D0.4;0.6 μg/kg,group D0.6;0.8μg/kg,group D0.8;1.0 μg/kg,group D1.0)or saline(group S)and fentanyl 1.0 μg/kg before anesthesia induce.The initial plasma concentration of propofol was set 3.0 μg/ml,and administrated with the model of Marsh.The ECe50 of propofol for hysteroscopy was measured by using an up-and-down sequential method with an adjacent concentration gradient at 1.2 to inhibit purposeful movements.The hemodynamic parameters,and anaesthesia associated adverse events were assessed.The time of procedue and recovery,and the requirement of propofol was recorded,the postoperative recovery characters were also recorded.Results:The ECe50 of propofol was significantly lower in the groups D0.8 and D1.0 compared to the group S(P<0.05);the dosage of propofol was significantly lower in the groups D0.6,D0.8,and D1.0 than in the group S,and that in the groups D0.8 and D1.0 than in the D0.4 group(P<0.05).There was no significant difference in the incidence of hypotension(P>0.05).The heart rate was significantly lower in all groups of dexmedetomidine,and the subjects in the groups D0.8 and D1.0 had lower occurrence of respiratory depression and higher incidence of bradycardia than those in groups S and D0.4(P<0.05).The subjects in the groups D0.8 and D1.0 had a higher comfort score compared with those in the group S postoperatively.In t0 and t1,the Ramsay scores were higher in the groups D0.8 and D1.0 than in the group S(P<0.05).There was no statistical difference in other indexes.Conclusion:In hysteroscopic surgery,co-administered with dexmedetomidine dose-dependently reduced the ECe50 and dosage of propofol,decreased the incidence of respiratory depression,and improved recovery quality.Administrated a dosage of 0.8 μg/kg dexmedetomidine was no difference for ED50 and requirement of propofol compare to higher dosage,and that high doses of(>0.8μg/kg)increased the risk of bradycardia and delay recovery.