Objective: To observe the influence of low dose dexmedetomidine(Dex) on
internal carotid artery blood flow in(Chinese).Methods:
30 young healthy patients(ASA I~II) were randomly divided into 2 groups,Dexmedetomidine group(Group D,n=15) or control group(Group C,n=15).In Group D,intravenous 0.4μg·kg~(-1)·h~(-1) Dex was maintained for 30 minutes after a loading dose of 0.4μg/kg Dex given in 5 minutes,whereas in Group C,0.9% normal saline was given as control.The MAP,HR,SpO_2,P_(ET)CO_2 were monitored,and the basic diameter,
blood flow velocity,blood flow of common carotid(artery) and
internal carotid artery were measured with AU_4 color Doppler.The above parameters were recorded at the time before Dex infusion(T_0),after loading dose(T_1),and at 5,10,15,20,25,30 minutes(T_(2~7)) after continuous infusion.Results: Demographic data of the patients in both groups were comparable.The blood flow velocity,blood flow of common carotid artery increased(P<0.05)firstly and then fell back to normal after the loading dose of Dex.The blood flow velocity and blood flow of the internal carotid artery decreased by 17%~21%(P<(0.05))at T_5 and T_6 compare with T_0.Dex infusion also produced HR and MAP decrease of 15.2% and 19.8% respectively(P<(0.05)),however the change in HR and MAP was not clinically significant.The blood flow velocity and blood flow of the internal carotid artery have no correlated with MAP(r =0.165 and 0.119).No respiratory depression was observed.Conclusion: Low dose Dex((0.4μg)/kg loading dose followed by 0.4μg·kg~(-1)·h~(-1) continuous infusion)decrease the blood flow of internal carotid artery simultaneously and it has no correlated MAP.