Pentobarbital vs chloral hydrate for sedation of children undergoing MRI: efficacy and recovery characteristics.

Abstract

Chloral hydrate (CH) sedation for magnetic resonance imaging (MRI) is associated with significant failure rates, adverse events and delayed recovery. Pentobarbital (PB), reportedly produces successful sedation in 98% of children undergoing diagnostic imaging. This study compared the efficacy, adverse events and recovery characteristics of CH vs PB in children undergoing MRI. With Institutional Review Board approval and written consent, children were randomly assigned to receive intravenous (i.v.) PB (maximum 5 mg x kg(-1) in incremental doses) or oral CH (75 mg x kg(-1)) prior to MRI. Sedation was augmented with 0.05 mg x kg(-1) doses of i.v. midazolam (maximum 0.1 mg x kg(-1)) as necessary. Adverse effects, including hypoxaemia, failed sedation, paradoxical reactions and behavioural changes, the return of baseline activity, and parental satisfaction were documented. The quality of MRI scans was evaluated by a radiologist blinded to the sedation technique. PB facilitated an earlier onset of sedation (P = 0.001), higher sedation scores (P = 0.01), and less need for supplemental midazolam compared with CH. Severe hypoxaemia occurred in two children (6%) in the PB group. Fourteen per cent of the PB group experienced a paradoxical reaction, 9% sedation failure and 11% major motion artefact, compared with 0% (P = 0.05), 3 and 2% (P = NS), respectively, in the CH group. CH and PB were both associated with a high incidence of motor imbalance, and agitation. However, children who received PB had a slower return to baseline activity (P = 0.04). Although PB facilitated a quicker sedation onset and reduced the requirement for supplemental sedation, it produced a higher incidence of paradoxical reaction and prolonged recovery with a similar failure rate compared with CH.