The Effect Of Dexmedetomidine On Propofol Requirement For Loss Of Consciousness

Objective To evaluate the effect of different doses of dexmedetomidine?DEX?on propofol requirement for loss of consciousness?LOC?and bispectral index?BIS?values predicting LOC during propofol administration.Methods 73 patients aged 18-60 years,BMI 18.5-24.0 kg·m-2 were scheduled for general anesthesia.All patients were randomly assigned to one of three groups: the control group?C group,n=24?,the DEX 0.5 ?g·kg–1 group?D₁ group,n=24?and the DEX 1.0 ?g·kg–1 group?D₂ group,n=25?.The patients were received saline infusion,DEX 0.5 ?g·kg–1 infusion or DEX 1.0 ?g·kg–1 infusion for 10 minutes,respectively.And then propofol was infused at 20 mg·kg-1·h-1.The propofol requirement for LOC,BIS value at LOC,and time to LOC were recorded.Results At the time of LOC,the propofol requirement was 1.77±0.43 mg·kg-1 in the C group,1.13±0.33 mg·kg-1 in the D₁ group,and 0.79±0.31 mg·kg-1 in the D₂ group;the BIS value at LOC was 61±3.5 in the C group,67±3.9 in the D₁ group,and 68±3.8 in the D₂ group;the time to LOC was 314±59 s in the C group,210±53 s in the D₁ group and 138±56 s in the D₂ group,respectively.There were significant differences among three groups in the propofol requirement and time of LOC?P<0.05?.The BIS value was higher in the DEX groups compared with the C group?P<0.05?,but there was no difference between the two DEX groups?P>0.05?.Conclusion The study shows that DEX reduce the propofol requirement for LOC.DEX pre-administration reduce the BIS value degree at LOC induced by propofol.