Study On The Effective Sedative Dose Of Dexmedetomidine In Children

Objective:To Explore the effective sedative dose of dexmedetomidine intravenous infusion in pediatric patients at different ages,and to analyze the effect of age on the effectiveness of dexmedetomidine.Method:Pediatric patients scheduled for lower limb and perineum and inguinal surgery with caudal block were enrolled.They were allocated to four groups depending on age:the newborn group（1～28 d）,infant group（1～12 m）,young children group（1～3y）and children group（3～10y）.When they arrived in the operating room,the basic monitoring was established.Then the patients in each group received a bolus dose of dexmedetomidine.The time of bolus is 10 minute.The blood pressure（MAP）,heart rate（HR）and saturation of peripheral oxygen（SpO₂）were recorded before taking DEX（T₀）,5 minutes（T₁）,10 minutes（T₂）,15 minutes（T₃）,20 minutes（T₄）,25 minutes（T₅）and 30 minutes（T₆）after administration,and adverse reactions such as nausea,vomiting and shivering were also recorded.Sedation levels were assessed by The Alertness/Sedation score and the dosage of each child was determined by Dixon and Massey sequential method.By calculating the mean of the midpoint numerical value of all eight crossovers in each group to analysis the median effective dose(ED₅₀)of dexmedetomidine.In addition,the ED₅₀and 95%effective dose(ED₅₀)with 95%confidence interval（CI）for dexmedetomidine were also calculated by Probit analysis.Result:The ED₅₀ of dexmedetomidine to provide effective sedation by calculating the mean of the midpoint dose for the neonate group,infant group,young children group and children group was（0.49±0.07）ug/kg,（0.74±0.10）ug/kg,（0.81±0.10）ug/kg,（0.84±0.10）ug/kg,respectively.The ED₅₀ of dexmedetomidine with its 95%CI to provide effective sedation by Probit analysis for the neonate group,infant group,young children group and children group was 0.44ug/kg（95%CI,0.40～0.49ug/kg）,0.68ug/kg（95%CI,0.62～0.74ug/kg）,0.79ug/kg（95%CI,0.72～0.87ug/kg）and 0.80 ug/kg（95%CI,0.73～0.88ug/kg）,respectively.The ED₉₅ of dexmedetomidine with its 95%CI was 0.58 ug/kg（95%CI,0.52～0.71ug/kg）,0.90ug/kg（95%CI,0.81～1.09ug/kg）,1.04 ug/kg（95%CI,0.94～1.27ug/kg）and 1.06 ug/kg（95%CI,0.96～1.29ug/kg）.Conclusion:Children of different age groups have different sensitivities to dexmedetomidine,among which neonates have the highest sensitivity,followed by that infants,while there is no statistical difference between infants and children.Dexmedetomidine infusion has the effect of negative heart rate and depressing blood pressure in pediatric patients.