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

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.