Background
The adverse event profile of sedation with benzodiazepines, propofol and opioids leaves a window of opportunity to consider alternative agents. Dexmedetomidine (DEX) is particularly attractive in children for whom the preservation of spontaneous ventilation and airway tone is preferable.

Case Report
 An 18-month-old infant male (13 Kg) with macrocephaly, developmental delay, kyphoscoliosis and laryngomalacia was scheduled for brain and neuroaxial MRI. A peripheral intravenous line was secured and midazolam 0.05mg/kg administered.   A loading dose of DEX 2μg/kg was given over 10 minutes and an infusion started at 1μg/kg/h, with the purpose of achieving a minimum Ramsay score of 4. Supplemental cetamine 1mg/kg was administered as rescue. Hemodynamic and respiratory profiles were maintained within baseline limits. Discharge criteria were met 60 minutes after the procedure.

Discussion
Currently DEX is not approved for use in the pediatric population, however its use in children has been described in the literature for almost a decade. It is an α2-adrenergic agonist that provides sedation paralleling natural sleep with minimal respiratory depression. Evidence suggests that, to provide adequate sedation, either supplemental sedatives must be administered or the bolus or infusion rate of DEX must be more rapid than that reported initially. Mason KP et al. described an effective sedation protocol for MRI with DEX 2-3μg/kg IV loading dose followed by an infusion of 2µg/kg/h. Bradycardia, hypotension and sinus arrhythmia have been reported with these doses, although they have not required treatment. Administration of DEX in conjunction with cetamine has been described and leads to improved quality of sedation with reduced incidence of adverse effects. This association has opposite cardiovascular effects and seems to be the key to maintain spontaneous ventilation while preserving hemodynamic stability.

Learning points
Sedation in remote locations is a challenge. The safety profile of DEX suggests that it can be used effectively and safely in children, with potential to be the drug of choice in cases with increased risk of airway collapse.

References:
(1) Tamman T. Comparison of the efficacy of dexmedetomidine, ketamine and a misture of both for pediatric MRI sedation. Egyptian Journal of Anaesthesia. 2013; 29:241-246
(2) Mahmoud M, Mason KP. Dexmedetomidine: review, update and future considerations of paediatric perioperative and periprocedural applications and limitations. British Journal of Anaesthesia. 2015; 171-82

Dexmedetomidine: the answer for difficult cases?