ORAL CHLORAL HYDRATE PROVIDES EFFECTIVE AND SAFE SEDATION IN PEDIATRIC MAGNETIC-RESONANCE-IMAGING

Sedation is routinely required for successful Magnetic Resonance imaging in infants and children. Five hundred and ninety-six paediatric patients (270 female and 326 male, age (mean +/- SD) 41 +/- 30 months and weight 14.8 +/- 6.5 kg) entered an open, non-comparative, prospective study to assess oral chloral hydrate sedation in a large and homogeneous paediatric population undergoing Magnetic Resonance imaging. Chloral hydrate syrup 70 mg/ml was administered 20-40 min prior to the procedure. Effective sedation was reached in 94-1% with a total dose (mean +/- SEM) of 68 +/- 1 mg/kg (range 20-170 mg/kg). Statistical analysis of sedation failures vs. successful examinations after the total dose showed significant differences for dose (62 +/- 4 vs. 69 +/- 1 mg/kg; P<0.05), age (64 +/- 7 vs. 40 +/- 1 months; P<0.001) and weight (19.8 +/- 1.5 vs. 14.5 +/- 0.0 kg; P<0.001). Effectiveness fell to around 80% in children with encephalic white matter alterations, medullary tumours or syringohydromyela (P=0.07). The mean time of onset of sedation was 26 +/- 1 min, and the mean time to spontaneous awakening after the completion of the Magnetic Resonance examination was 38 +/- 2 min. Fifty-nine children (9.9%) experienced adverse reactions, with nausea and vomiting being the most common (n=41), followed by nervousness and unusual excitement (n=6). Discriminant function analysis identified age and total dose as the quantitative variables helping to differentiate between sedation failures and satisfactory examinations (sensitivity=0.73, and specificity=0.61; r=0.20, P<0.001). Sedation failure rates were very low (<5%) for children under 36 months old, but still low (<7.5%) for children up to 7 years old. Older children (>7 years) showed unacceptable failure rates (>15%). Low sedation failure rates (<5%) and few adverse reactions (<10%) were obtained in the 61.70 mg/kg and 71-80 mg/kg dose ranges. Lower doses produced higher sedation failure rates, while higher doses increased the incidence of adverse reactions. Assuming a recommended sedative paediatric dose of 70 mg/kg, and the possibility to re-administer half the dose if adequate sedation was not achieved, a maximum total dose per procedure around 100 mg/kg is proposed. We conclude that oral chloral hydrate is a safe and consistently effective short-term sedative, and it probably should be considered the drug of choice in infants and children undergoing Magnetic Resonance examinations.