Effect of different loading doses of dexmedetomidine as an anesthetic adjuvant on hemodynamics in patients less than 65 years old

Objective To explore the effect of different loading doses of dexmedetomidine on hemodynamics under general anesthesia in the patients aged less than 65 years.Methods Sixty patients(age 65 years old,operation time≤2h)under general anesthesia were randomly divided into group A(1.0μg/kg dexmedetomidine),group B(0.8μg/kg dexmedetomidine)and group C(0.6μg/kg dexmedetomidine).There were 20 patients in each group.The continuous infusion of dexmedetomidine for each group was at a rate of 0.5μg·kg-1·h-1.Cardiac output(CO),cardiac index(CI),stroke volume(SV),systolic blood pressure(SBP),diastolic blood pressure(DBP)and heart rate(HR)were recorded before infusion of dexmedetomidine(T0),at 3 min(T1),6 min(T2),9min(T3),10 min(T4),0.5h(T5),1h(T6)and 2h(T7)after pump infusion. The consumption of narcotic analgesic and vasoactive drugs were also recorded.Results Compared with the values at T0,SBP and DBP at T2 were significantly increased,whereas SBP and DBP at T5 and CO,CI and SV at T6 and T7 were significantly decreased in all patients(all P0.05).SBP,CO and CI at T6 and T7 in group A and group B were significantly lower than those in group C(all P0.05).HR of group A and group B at T3 and T4 were significantly slower than that of group C(all P0.05).The consumption of fentanyl in group A and group B was significantly less than that in group C(all P0.05).But there was no significant difference in the consumption of fentanyl between group A and group B(P0.05).The use of atropine and phenylephrine in group A was markedly frequent than that in the other two groups(all P0.05).Conclusion As an anesthetic adjuvant, dexmedetomidine has a negative effect on SBP,HR,CO and CI.It can reduce the dosage of other anesthetic,but require more frequent administration of anesthetic.The loading dose of 0.6μg/kg dexmedetomidine is safe and effective and can minimize negative consequences of sedation.