Comparison of Two Different Intranasal Doses of Dexmedetomidine in Children for Magnetic Resonance Imaging Sedation

Anaesthetic agents used for magnetic resonance imaging (MRI) in paediatric patients should cause few adverse effects and allow fast anaesthetic induction and recovery. The administration route is also important and should be minimally invasive. In this study, we aimed to compare two different doses of intranasal dexmedetomidine applied to children for MRI sedation.

Sixty patients between 1 and 10 years of age with American Society of Anesthesiologists Physical Status classification I or II who were scheduled for MRI were recruited into this prospective, randomized, double-blind study. Intranasal dexmedetomidine was administered at doses of 3 µg kg⁻¹ (Group 1) and 4 µg kg⁻¹ (Group 2) before imaging. Heart rate (HR), peripheral oxygen saturation, respiratory rate and Ramsay Sedation Scale (RSS) scores were recorded before the anaesthetic induction of sedation and every 10 min until discharge. If intranasal sedation failed, an intravenous cannula was placed and propofol was applied as a rescue anaesthetic. Bispectral Index (BIS) scores were also recorded before and after MRI. We recorded onset time of sedation, mood at separation from parents (defined as parental separation score), imaging quality, MRI duration, rescue anaesthetic requirement, total duration of sedation, recovery duration, parents’ satisfaction and adverse effects.

The results related to age, weight and adverse effects were not statistically different between the groups. The parental separation score was significantly higher in Group 2 (P = 0.003). Rescue anaesthetic requirement was significantly higher in Group 1 (P = 0.002). The results related to recovery duration, MRI duration, parents’ satisfaction, onset time of sedation and total duration of sedation were not statistically different. HR was significantly lower in all time intervals compared with basal values in both groups. In Group 2, RSS scores were significantly higher in the 30th, 40th and 50th min. The BIS scores in Group 2 were lower at the 50th min. Neither bradycardia nor oxygen desaturation were observed. Imaging studies were completed successfully in all patients.

Based on lower rescue anaesthetic requirements, sufficient sedation and parental separation scores in Group 2, intranasal dexmedetomidine 4 µg kg⁻¹ was more efficient than intranasal dexmedetomidine 3 µg kg⁻¹. The intranasal route may be an alternative noninvasive route to apply drugs for MRI sedation in paediatric patients.