Intranasal dexmedetomidine sedation for paediatric MRI by radiology personnel
A retrospective observational study
European Journal of Anaesthesiology
June 2023 by Dr Jon Stacey
This Scandinavian study adds to the evidence base around needle-free sedation techniques for paediatric imaging, itself the subject of a recent systematic review (https://www.bjanaesthesia.org/article/S0007-
0912(22)00517-7/fulltext), summarised elegantly by Dr Burton in the January-February edition of this forum (Needle-free pharmacological sedation techniques in paediatric patients for imaging procedures: a systematic review and meta-analysis - SPANZA).
The authors identify access to paediatric anaesthetic services as a common rate-limiting step for the timely provision of paediatric MRI, and moreover suggest an alternative model that is both largely needle- and anaesthetist-free.
Over a period of 4 years, 1091 appropriately-triaged children of mean age 34 months and ASA 1 or 2 received nasal dexmedetomidine alone as sedation for MRI scans of predicted duration less than one hour, administered by radiology staff in the absence of an anaesthetist. The initial dose was of 4mcg/kg, with a subsequent 2mcg/kg if the child was deemed ‘not sedated enough’.
Within the limits of the study design, the results seem appealing; 93% of scans commenced were completed as planned with adequate image acquisition.
The mean time from first administration of dexmedetomidine to scan readiness is not clear, nor the time at which a second dose (required in 36% of children) was adjudged to be required or effective. Further, there is a poorly-defined cohort of children in whom adequate sedation was never achieved despite repeat dosing, and who do not appear in the subsequent analysis.
The safety data is confusingly presented but appears re-assuring (especially given the dexmedetomidine protocol did not mandate any pre-procedural fasting); 4 children had minor de-saturations requiring only brief supplemental oxygen, and 5 had bradycardias below the 1st centile for age, with none requiring intervention. Closer inspection however suggests that agreed indications for seeking anaesthetic input were not always followed by radiology staff, and moreover blood pressure was not measured at any point during the period of sedation.
In the discussion the authors argue their results support the safety and efficacy of nasal dexmedetomidine for paediatric MRI, thereby enabling radiology departments to take greater ownership of the process, including those previously lacking the opportunity. They go on to extrapolate that paediatric anaesthetists need not be part of the process beyond a consultative role.
Whilst no doubt an interesting study, I’m not sure their findings yet support their confidence.