Effects of different doses of dexmedetomidine on the hemodynamic response of ephedrine

Objective To compare the effects of different doses of dexmedetomidine on the hemodynamic response of ephedrine on general anesthesia patients.Methods Sixty-six cases of patients undergoing elective orthopedics operations under general anesthesia(20-60 years old,50-75 kg,ASA grade:Ⅰ-Ⅱ)were randomly divided into three groups(n=22in each group):normal saline group(group C),low dose of dexmedetomidine group(group D1)and high dose dexmedetomidine group(group D2).Before induction of anesthesia,patients received continuous intravenous pumping of dexmedetomidine 0.4μg/kg in group D1 or 0.8μg/kg in group D2 for ten minutes and then 0.4μg·kg-1·h-1 prior to anesthesia induction.Group C was injected with equivalent normal saline.5min after laryngeal mask insertion,ephedrine 0.1 mg/kg were intravenous administered in all three groups.The heart rate,blood pressure of the patients after entering the operation room(T0),anesthesia before induction(T1),after induction(T2),after laryngeal mask insertion(T3),administration of ephedrine(T4)and the maximum(Tmax)value and time of heart rate and blood pressure in 10 minutes.The difference between Tmax and T4 values were expressed asΔSBP,ΔDBP and ΔHR.Results The TBPof groups D1 and D2 was significantly shorter than that in group C(P0.05).there was no statistical significance between the The THRof three groups of patients.The SBP,DBP,HR in groups D1 and D2was significantly lower than that in group C(P0.05),And the changes of the group D2 was significantly lower than that in the group D1(P 0.05).Conclusion Dexmedetomidine can enhance the pressor response of ephedrine and accelerate the onset time in general anesthiesa patients,and the pressor response of ephedrine with 0.8μg/kg loading dose of dexmedetomidine was stronger than that of 0.4μg/kg loading dose.