Effect of different doses of dexmedetomidine hydrochloride on the pressor effect in orthopedic general anesthesia patients

ObjectiveTo investigate the effects of different doses of dexmedetomidine hydrochloride on the pressor effect in orthopedic general anesthesia patients.

MethodsOne hundred and twenty surgical patients with ASA grade Ⅰ or Ⅱ were divided into the small dose group(Dex1 group, n=40), large dose group(Dex2 group, n=40) and control group(group C, n=40) according to random number table method.The Dex1 group, Dex2 group and control group were injected with 0.5 μg/kg of dexmedetomidine hydrochloride before anesthesia induction, 0.8 μg/kg of dexmedetomidine hydrochloride and equal amount of 0.9% sodium chloride solution, respectively.All patients were intravenously injected with 0.1mg/kg of ephedrine after 5 min of Laryngeal-mask-airway(LMA).The heart rate(HR), systolic blood pressure(SBP) and diastolic blood pressure (DBP) were compared among three groups after entering the operating room(T₁), before anesthesia induction (T₂), after 1min of anesthesia induction(T₃), LMA(T₄), and immediately after injection of ephedrine(T₅).The time of the maximum HR and blood pressure(MtHR and MtBP) after 10 min of injection of ephedrine, and the differences value of the maximum value of HR, SBP and DBP to the value at T₅(ΔHR, ΔDBP and ΔSBP) were compared among three groups.

ResultsThe HR, SBP and DBP in Dex1 group and Dex2 group were lower than those in group C at T₂, T₃, T₄ and T₅(P < 0.01), the SBP and DBP in Dex2 group were lower than those in Dex1 group at T₂, T₃, T₄ and T₅(P < 0.01), and the differences of HR between Dex1 group and Dex2 group at T₂, T₃, T₄ and T₅ were not statistically significant(P>0.05).The ΔHR, ΔDBP and ΔSBP in Dex1 group and Dex2 group were significantly higher than those in group C(P < 0.01), and the MtHR and MtBP in Dex1 group and Dex2 group were significantly lower than those in group C(P < 0.01).The ΔHR, ΔDBP and ΔSBP in Dex2 group were lower than those in Dex1 group(P < 0.01), and there was no statistical significance in the MtHR and MtBP between the Dex1 group and Dex2 group(P>0.05).

ConclusionsDexmedetomidine hydrochloride can enhance the the pressor effect and accelerate the response time, and the pressor effect of 0.8 μg/kg is significantly better than that of 0.5 μg/kg in orthopedic general anesthesia patients.