Dexmedetomidine as a sole sedative for procedural sedation in preterm and neonate infants: A retrospective analysis.

Study summary

This is a retrospective single-center cohort study from University Hospital of Cologne, Germany looking at use of IV dexmedetomidine as sedation for MRI in premature and term infants less than 60 weeks post-conceptual age weighing <5kg. Exclusion criteria were ASA-5 patients, and those already intubated.
The main reason for doing this study is the purported fewer neurotoxic effects and possible neuroprotective effects with dexmedetomidine compared with other anaesthetic agents. Primary endpoint was adequate sedation for successful imaging, without additional intervention or patient displacement due to apnoea (i.e., interruption of ETCO2 >10 seconds) or desaturation (i.e., SpO2 < 90%). Secondary endpoints were age-appropriate bradycardia incidence, other cardiopulmonary complications, and need for rescue sedative.
Between December 2016 to December 2018, all medical records for children requiring sedation for MRI (n=1441) were reviewed and 39 met inclusion criteria. Of these 39 cases, 34 received a dexmedetomidine loading dose ranging between 0.34-3.64 mcg/kg (median dose = 1.39 mcg/kg), and the remaining 5 patients received dexmedetomidine infusion without loading dose as they were still/sleeping after positioning on MRI table. Dexmedetomidine infusions ranging from 0.50-3.50 mcg/kg/hour (median dose = 1 mcg/kg/hr) were given to 36 infants, and the remaining 3 received dexmedetomidine bolus only due to expected shorter duration of imaging.
Imaging was reported as successful in all 39 cases; 3 required a repeat MRI sequence due to movement and they were given rescue sedative medication with bolus of propofol (2 cases) and ketamine (1 case).
There was no apnoea, and 10 patients were given nasal oxygen supplementation with 9 of them already on oxygen therapy pre-MRI; the lowest recorded SpO2 was 90%, with median drop of 2.1% in the 12 children of normal weight (>10th centile) and 2.0% in the remaining 27 children who were small for gestational age.
Heart rate decreased in all 39 infants with 8 infants meeting bradycardia criteria per Hartmann et al, or 15 infants per Fleming et al criteria; the severity of bradycardia appeared to correlate with higher rate of dexmedetomidine infusion (p=0.039). The bradycardia stopped with cessation of dexmedetomidine infusion, and none were associated with change in blood pressure.

Limitations stated by the authors were the small number of patients, possible concern with accuracy of handwritten records, and limited ability to quantify depth of sedation due to nature of the MRI suite.

Take home message

Whilst some premature babies and infants less than 60 weeks post-conceptual age can have a successful MRI scan following a “feed and wrap”, it is difficult to decide on the ‘best’ sedation technique for those babies who need it. I agree with the authors that less medication used is better; given the minimal significant side effects with dexmedetomidine in this study and the purported neurological advantage of dexmedetomidine compared to other sedatives, a dose-finding prospective study would better help guide its use. Potentially, as more data becomes available, dexmedetomidine as sedation can also be used for other minimally invasive procedures such as nuclear imaging, vascular and neuraxial access.

Reviewed by Dr K.C. Law