Sedative, haemodynamic and respiratory effects of dexmedetomidine in children undergoing magnetic resonance imaging examination: preliminary results

Br J Anaesth. 2005 Jun;94(6):821-4. doi: 10.1093/bja/aei119. Epub 2005 Mar 11.


Background: We evaluated the sedative, haemodynamic and respiratory effects of dexmedetomidine and compared them with those of midazolam in children undergoing magnetic resonance imaging (MRI) procedures.

Methods: Eighty children aged between 1 and 7 yr were randomly allocated to receive sedation with either dexmedetomidine (group D, n=40) or midazolam (group M, n=40). The loading dose of the study drugs was administered for 10 min (dexmedetomidine 1 microg kg(-1) or midazolam 0.2 mg kg(-1)) followed by continuous infusion (dexmedetomidine 0.5 microg kg(-1) h(-1) or midazolam 6 microg kg(-1) min(-1)). Inadequate sedation was defined as difficulty in completing the procedure because of the child's movement during MRI. The children who were inadequately sedated were given a single dose of rescue midazolam and/or propofol intravenously. Mean arterial pressure (MAP), heart rate (HR), peripheral oxygen saturation (SpO2) and ventilatory frequency (VF) were monitored and recorded during the study.

Results: The quality of MRI was significantly better and the rate of adequate sedation was higher in group D than in group M (P<0.001). In group D, the requirement for rescue drugs was lower and the onset of sedation time was shorter than in group M (P<0.001). MAP, HR and VF decreased from baseline during sedation in both groups (P<0.001).

Conclusions: Dexmedetomidine provided adequate sedation in most of the children aged 1-7 yr without haemodynamic or respiratory effects during MRI procedures.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial

MeSH terms

  • Blood Pressure / drug effects
  • Child
  • Child, Preschool
  • Conscious Sedation / methods*
  • Dexmedetomidine / pharmacology*
  • Drug Administration Schedule
  • Female
  • Heart Rate / drug effects
  • Hemodynamics / drug effects*
  • Humans
  • Hypnotics and Sedatives / pharmacology*
  • Infant
  • Magnetic Resonance Imaging
  • Male
  • Midazolam / pharmacology
  • Prospective Studies
  • Respiration / drug effects*


  • Hypnotics and Sedatives
  • Dexmedetomidine
  • Midazolam