Determination of effective dose of dexmedetomidine administered intranasally combined with oral midazolam sedation for pediatric MRI:a modified sequential study
Objective To determine the effective dose of dexmedetomidine administered intranasally combined with oral midazolam sedation before pediatric magnetic resonance image(MRI).Methods This is a prospective modified sequential study.Children scheduled for MRI at the Children's Hospital of Zhejiang University School of Medicine from February to March 2023,aged 1 month to 6 years old,with a weight of 6.0-23.5 kg,were enrolled in this study.All children received 0.5 mg/kg oral midazolam,followed by intranasal dexmedetomidine.The initial dose of dexmedetomidine was 0.5 μg/kg,and the intranasal dose of dexmedetomidine was determined using the modified Dixon's up-and-down method with increments or decrements of 0.1 μg/kg.Probit analysis was used for calculating the half effective dose(ED50),95%effective dose(ED95)and the corresponding 95%confidence interval(CI)of intranasal dexmedetomidine combined with oral midazolam for pediatric sedation during MRI.The sedation onset time,wake-up time,vital signs and adverse reactions were recorded.Results Among all the children,the sedation onset time of successful sedation children was(31.21±7.47)min,and the wake-up time was(81.21±26.04)min.The ED50 for effective sedation with intranasal dexmedetomidine combined with oral medication at a dose of 0.5 mg/kg was calculated to be 0.392 μg/kg,with a 95%CI of 0.302-0.461 μg/kg;the ED95 was 0.549 μg/kg,with a 95%CI of 0.473-0.996 μg/kg.There was a statistically significant difference(P<0.05)in heart rate and diastolic blood pressure after sedation compared to the baseline before medication.Two cases of restlessness during the awakening period were observed,but no other adverse reactions occurred.Conclusions The sedation regimen of intranasal dexmedetomidine combined with oral midazolam is non-invasive,easy to implement,safe,and effective.It can be widely used in pediatric MRI.