High dose dexmedetomidine as the sole sedative for pediatric MRI

Paediatr Anaesth. 2008 May;18(5):403-11. doi: 10.1111/j.1460-9592.2008.02468.x. Epub 2008 Mar 18.


Objective: This large-scale retrospective review evaluates the sedation profile of dexmedetomidine.

Aim: To determine the hemodynamic responses, efficacy and adverse events associated with the use of high dose dexmedetomidine as the sole sedative for magnetic resonance imaging (MRI) studies.

Background: Dexmedetomidine has been used at our institution since 2005 to provide sedation for pediatric radiological imaging studies. Over time, an effective protocol utilizing high dose dexmedetomidine as the sole sedative agent has evolved.

Methods/materials: As part of the ongoing Quality Assurance process, data on all sedations are reviewed monthly and protocols modified as needed. Data were analyzed from all 747 consecutive patients who received dexmedetomidine for MRI sedation from April 2005 to April 2007.

Results: Since 2005, the 10-min loading dose of our dexmedetomidine protocol increased from 2 to 3 microg.kg(-1), and the infusion rate increased from 1 to 1.5 to 2 microg.kg(-1).h(-1). The current sedation protocol progressively increased the rate of successful sedation (able to complete the imaging study) when using dexmedetomidine alone from 91.8% to 97.6% (P = 0.009), reducing the requirement for adjuvant pentobarbital in the event of sedation failure with dexmedetomidine alone and decreased the mean recovery time by 10 min (P < 0.001). Although dexmedetomidine sedation was associated with a 16% incidence of bradycardia, all concomitant mean arterial blood pressures were within 20% of age-adjusted normal range and oxygen saturations were 95% or higher.

Conclusion: Dexmedetomidine in high doses provides adequate sedation for pediatric MRI studies. While use of high dose dexmedetomidine is associated with decreases in heart rate and blood pressure outside the established 'awake' norms, this deviation is generally within 20% of norms, and is not associated with adverse sequelae. Dexmedetomidine is useful as the sole sedative for pediatric MRI.

MeSH terms

  • Adjuvants, Anesthesia
  • Adolescent
  • Anesthesia Recovery Period
  • Bradycardia / chemically induced
  • Child
  • Child, Preschool
  • Conscious Sedation*
  • Contraindications
  • Dexmedetomidine / administration & dosage*
  • Dexmedetomidine / adverse effects
  • Dose-Response Relationship, Drug
  • Female
  • Humans
  • Hypnotics and Sedatives / administration & dosage*
  • Hypnotics and Sedatives / adverse effects
  • Infant
  • Infusions, Intravenous
  • Magnetic Resonance Imaging*
  • Male
  • Pentobarbital
  • Quality Assurance, Health Care
  • Retrospective Studies


  • Adjuvants, Anesthesia
  • Hypnotics and Sedatives
  • Dexmedetomidine
  • Pentobarbital