The Study On The Effective Dose Of Dexmedetomidine For Providing Sedation In Female Patients

Spinal anesthesia is widely employed in lower limb surgery and lower abdominal surgery.However,patients may experience anxiety and nervous during the surgery,especially for parturients who not only worry about the surgery,but also pay attention to the fetus.After the fetus delivery,parturients are easy to emotional and sympathetic excitement,coupled with regular intravenous infusion of oxytocin after fetus delivery and surgery related visceral traction pain,can further aggravate the bad emotion and stress response.Dexmedetomidine as a highly selective α2 receptor agonist with sedative,analgesic and anxiolytic properties,not only can provide favorable sedation and analgesia,but also effectively reduce or eliminate bad emotion and stress response.Age is one of the most important factors that affect the pharmacokinetics and pharmacodynamics of drugs,and the increased sensitivity of drug was obvious in old patients.Now few study reported the effective sedative dose of dexmedetomidine in female patients.Therefore,the purpose of this study was to evaluate the effect of age on dexmedetomidine for providing effective sedation in female patients,and the difference of the effective sedative dose of dexmedetomidine in parturients after delivery and nonpregnant women.OBJECTIVE1.To investigate the effect of age on single-dose dexmedetomidine for providing effective sedation in female patients.2.To evaluate the difference of the effective sedative dose of dexmedetomidine in parturients after delivery and nonpregnant women.METHODSFemale patients,undergone elective lower limb surgery with combined spinal-epidural anesthesia,were enrolled.Female patients were allocated to three groups depending on age:group Y(20～35 years),group M(40～60 years)and group O(65～79 years).Parturients between 35 and 42 weeks scheduled for planned cesarean section and nonpregnant women scheduled for lower abdominal surgery,under combined spinal and epidural anesthesia,were enrolled.In the parturient group,after the delivery of fetus and placenta,all parturients intravenously received single-dose dexmedetomidine over 15 min.In other groups,a bolus dose of dexmedetomidine was administered over 15 min after determining the sensory block level.The dose of each patient was determined by a modified two-stage sequential method.By calculating the mean of the midpoint dose of the four crossovers in the second stage in each group to analysis the median effective dose(ED50)of dexmedetomidine.In addition,the ED50 and 95%effective dose(ED95)with 95%confidence interval(CI)for dexmedetomidine were also calculated by probit analysis.RESULTSThe ED50 of dexmedetomidine to provide effective sedation by calculating the mean of the midpoint dose for group Y,group M and group O was(0.96±0.35)μg/kg,(0.99±0.35)μg/kg and(0.68 ± 0.46)μg/kg,respectively.The ED50 of dexmedetomidine with its 95%CI for providing effective sedation by probit analysis in group Y,group M and group O was 0.98 μg/kg(95%CI,0.93～1.03 μg/kg),0.96μg/kg(95%CI,0.92～1.00 μg/kg)and 0.66 μg/kg(95%CI,0.63～0.69 μg/kg),respectively.The ED95 of dexmedetomidine with its 95%CI was 1.13 μg/kg(95%CI,1.06～1.30 μg/kg),1.11 μg/kg(95%CI,1.05～1.26 μg/kg)and 0.76 μg/kg(95%CI,0.72～0.87 μg/kg),respectively.The ED50 of dexmedetomidine to provide effective sedation by calculating the mean of the midpoint dose for parturients and nonpregnant women were(1.73±0.46)μg/kg and(1.03±0.46)μg/kg.By a probit regression analysis,the ED50 of dexmedetomidine with its 95%CI for providing effective sedation in parturients and nonpregnant women were 1.69 μg/kg(95%CI,1.61～1.79μg/kg)and 0.98 μg/kg(95%CI,0.92～1.02 μg/kg).The ED95 of dexmedetomidine with its 95%CI was 1.93 μg/kg(95%CI,1.82～2.39 μg/kg)and 1.11 μg/kg(95%CI,1.05～1.35 μg/kg).There was no difference between group Y and group M on the EDso(P>0.0167).However,the ED50 in group O was smaller than that in group Y and group M(P<0.0167).The ED50 in nonpregnant women was significantly lower than that in parturients(P<0.05).CONCLUSIONThere was no difference between youth and middle-aged female patients on the ED50 of dexmedetomidine for providing effective sedation,while the ED50 in elderly female patients was significantly lower than that in youth and middle-aged female patients.In addition,the dexmedetomidine dose for providing effective sedation for parturients was higher than that for nonpregnant women.