Administration of oral chloral hydrate to paediatric patients undergoing magnetic resonance imaging.

Sedation is frequently required in children undergoing magnetic resonance imaging (MRI). 172 Paediatric patients (82 female and 90 male, age 42 +/- 26 months, weight 14.7 +/- 5.6 kg) entered an open, non-comparative, prospective study to assess the utilization of oral chloral hydrate. Chloral hydrate syrup (70 mg/ml) was administered 20-30 min prior to the procedure. Effective sedation was reached in 80.3% with an average initial dose of 55 mg/kg and in 93.6% with an average total dose of 65 mg/kg. Significant differences in effectivity were correlated with the dose (54 +/- 11 mg/kg in failure cases versus 66 +/- 16 mg/kg in effective cases; p < 0.05) and diagnosis (effectivity falls to 62.5% and 76.0% in children with medullar tumours and encephalic white matter alterations, respectively; p < 0.01). Average sleep induction time was 30 +/- 19 min, and average duration of sleep was 62 +/- 24 min. Adverse reactions occurred in 4.7%, with nausea, vomiting and stomach pain being the most common side-effects (3.5%). Multivariate statistical analysis selects total dose and age into the discriminant function, with a 100% relative percentage of correct classification. A simple method for optimizing the chloral hydrate dose in children is proposed: the dose in mg/kg is calculated as half the age in months + 50.