A Comparison of Dexmedetomidine-Midazolam with Propofol for Maintenance of Anesthesia in Children Undergoing Magnetic Resonance Imaging

BACKGROUND: Dexmedetomidine is an a, agonist that is currently being investigated for its suitability to provide anesthesia for children. We compared the pharmacodynamic responses to dexmedetomidine-midazolam and propofol in children anesthetized with sevoflurane undergoing magnetic resonance imaging (MRI). METHODS: Forty ASA 1 or 2 children, 1-10 yr of age, were randomized to receive either dexmedetomidine-midazolam or propofol for maintenance of anesthesia for MRI after a sevoflurane induction. Dexmedetomidine was administered as an initial loading dose (1 mu g/kg) followed by a continuous infusion (0.5 mu g . kg(-1) . h(-1)). Midazolam (0.1 mg/kg) was administered IV when the infusion commenced. Propofol was administered as a continuous infusion (250-300 mu g . kg(-1) . min(-1)). Recovery times and hemodynamic responses were recorded by one nurse who was blinded to the treatments. RESULTS: We found that the times to fully recover and to discharge from the ambulatory unit after dexmedetomidine administration were significantly greater (by 15 min) than those after propofol. Analysis of variance demonstrated that heart rate was slower and systolic blood pressure was greater with dexmedetomidine than propofol. Respiratory indices for the two treatments were similar. During recovery, hemodynamic responses were similar. Cardiorespiratory indices during anesthesia and recovery remained within normal limits for the children's ages. No adverse events were recorded. CONCLUSION: Dexmedetomidine-midazolam provides adequate anesthesia for MRI although recovery is prolonged when compared with propofol. Heart rate was slower and systolic blood pressure was greater with dexmedetomidine when compared with propofol. Respiratory indices were similar for the two treatments.