Comparison of the efficacy of dexmedetomidine, ketamine, and a mixture of both for pediatric MRI sedation

Aim
To compare the efficacy of intramuscular ketamine, dexmedetomidine, and a mixture of both for pediatric MRI sedation.
Subjects and methods
One-hundred and sixty-two children with ASA physical I–II were enrolled in a double-blind comparative study and assigned into three equal groups for sedation. Group D, patients received IM dexmedetomidine 3 μg/kg. Group K, patients received IM ketamine 4 mg/kg. Group DK, patients received a combination of IM dexmedetomidine 1.5 μg/kg and ketamine 2 mg/kg. Primary outcomes included incidence of failed sedation and the requirement of midazolam supplementation. Secondary outcomes were time to sedation, duration of sedation, and discharge time.
Results
The onset of satisfactory sedation was significantly shorter in the DK group in comparison with the D group (4.8 ± 1.6 vs. 16.8 ± 4.5 min), while no significant difference between the DK group and K group. The duration of sedation was significantly less in the DK group in comparison with the K group, and the discharge time was significantly less in the DK group in comparison with the D and K groups. The sedation failure rate was significantly lower in the DK group (5.6%) in comparison with the K group (22.2%) and the D group (27.8%). The use of rescue midazolam was significantly less in the DK group (0.03 ± 0.12 mg) in comparison with the K and D groups (0.21 ± 0.41 mg, 0.24 ± 0.41 mg, respectively). None of the patients experienced episodes of hypotension or bradycardia in the DK and K groups while four patients (7.4%) experienced episodes of hypotension and five patients (9.3%) experienced episodes of bradycardia in the D group.
Conclusion
In pediatric MRI sedation, the combination of IM dexmedetomidine and ketamine was superior to either IM dexmedetomidine or ketamine given individually with regard to the onset of sedation, the sedation failure rate, and hemodynamic stability.