Combined sedation in pediatric magnetic resonance imaging: determination of median effective dose of intranasal dexmedetomidine combined with oral midazolam.

Background: The exact median effective dose (ED50) of intranasal dexmedetomidine combined with oral midazolam sedation for magnetic resonance imaging (MRI) examination in children remains unknow and the aim of this study was to determine the ED50 of their combination.

Methods: This is a prospective dose-finding study. A total of 53 children aged from 2 months to 6 years scheduled for MRI examination from February 2023 to April 2023 were randomly divided into group D (to determine the ED50 of intranasal dexmedetomidine) and group M (to determine the ED50 of oral midazolam). The dosage of dexmedetomidine and midazolam was adjusted according to the modified Dixon's up-and-down method, and the ED50 was calculated with a probit regression approach.

Results: The ED50 of intranasal dexmedetomidine when combined with 0.5 mg∙kg oral midazolam was 0.39 µg∙kg [95% confidence interval (CI) 0.30 to 0.46 µg∙kg] while the ED50 of oral midazolam was 0.17 mg∙kg (95% CI 0.01 to 0.29 mg∙kg) when combined with 1 µg∙kg intranasal dexmedetomidine. The sedation onset time of children with successful sedation in group D was longer than in group M (30.0[25.0, 38.0]vs 19.5[15.0, 35.0] min, P < 0.05). No other adverse effects were observed in the day and 24 h after medication except one dysphoria.

Conclusion: This drug combination sedation regimen appears suitable for children scheduled for MRI examinations, offering a more precise approach to guide the clinical use of sedative drugs in children.

Trial Registration: Chinese Clinical Trial Registry, identifier: ChiCTR2300068611(24/02/2023).