Determination of optimal combined doses of oral midazolam and intranasal dexmedetomidine for use in pediatric magnetic resonance imaging.

Abstract

Background: Sedation is often required for infant and preschool children to obtain clear magnetic resonance imaging (MRI). This study was designed to determine the 95% effective dose (ED₉₅) of oral midazolam (MID) and intranasal dexmedetomidine (DEX) in combination for sedation in pediatric MRI.

Methods: We have used a biased coin design up-and-down sequential methodology. Initially, 144 patients were split into two groups. A total of 72 patients were randomly assigned to determine the ED₉₅ of DEX in combination with a fixed dose of 0.5 mg/kg MID, and 72 were given various doses of MID combined with a fixed dose of DEX at 1 µg/kg to determine the ED₉₅ of MID. ED₉₅ was calculated using isotonic regression. At last, the plan was to include 225 cases to test the sedation success rate of DEX combined with MID ED₉₅ dose. Adverse events were recorded.

Results: The ED₉₅ of DEX was 0.89 µg/kg (95% confidence interval (CI) 0.68 to 0.95) combined with a fixed dose of MID at 0.5 mg/kg. The ED₉₅ of MID was 0.47 mg/kg (95% CI 0.30 to 0.50) combined with a fixed intranasal dose of 1 µg/kg DEX. Using 1 µg/kg DEX combined with 0.5 mg/kg MID, the sedation success rate was 95.1% in a verification group of 225 children.

Conclusions: This study reports relatively low ED₉₅ doses of intranasal DEX and oral MID when DEX is determined with a fixed dose of MID and MID determined with a fixed dose of DEX. The combination provides efficient and safe sedation for young children for MRI scanning. Further validation is required.

Trial registration number: ChiCTR2300068611.