ABSTRACT
Objective To analyze the dose‐effects of different doses of dexmedetomidine for sedation and sleep of the patients under epidural nerve block anesthesia .Methods A total of 82 patients undergoing elective lower limbs surgery(ASA grade Ⅰ - Ⅱ) were randomly divided into 4 different doses of dexmedetomidine groups(group 1 ,n=19 ;group 2 ,n=22 ;group 3 ,n=20;group 4 , n=21) ,under continuous epidural nerve block ,the loading dose of dexmedetomidine 0 .7 ,0 .8 ,0 .9 ,1 .0μg · kg -1 · h-1 was intrave‐nously pumped for 30 min ,then pumped at a rate of 0 .7 ,0 .8 ,0 .9 ,1 .0 μg · kg -1 · h-1 in the group 1 ,2 ,3 and 4 respectively .If any patient in 4 groups fell asleep at less than half an hour ,the loading dose was stopped and the continuous dose was changed to pump , the drug administration was discontinued at wound dressing after operation .Whether the patient falling asleep was recorded ,and the mean arterial blood pressure ,heart rate at 4 time points of 10 ,30 ,60 ,90 min after infusion of dexmedetomidine were also recorded . The 50% effective dose(ED50 ) ,ED95 and 95% confidence interval(CI) were calculated by using the Probit method .Results ED50 and ED95 of dexmedetomidine were 0 .65μg/kg(95% CI:0 .36-0 .73μg/kg)and 1 .00 μg /kg(95% CI:0 .90-1 .74μg/kg) ,which could decrease the heart rate and increase the arterial blood pressure .Conclusion Although dexmedetomidine can decrease the heart rate and increase the arterial blood pressure ,but the patients quietly fall asleep without discomfort and pain occurrence by the intra‐venous administration under continuous epidural nerve block .