HIGH-DOSE CHLORAL HYDRATE SEDATION FOR CHILDREN UNDERGOING MR-IMAGING- SAFETY AND EFFICACY IN RELATION TO AGE

OBJECTIVE. Sedation is frequently essential for successful MR imaging, and chloral hydrate is the most commonly used drug for this purpose i n infants and children. Our experience with these patients suggested t hat this sedative is less effective in older children, even when admin istered in high doses. However, no prospective study comparing the eff icacy of chloral hydrate sedation for children of different ages under going MR imaging has been reported. Accordingly, we performed a study to evaluate the effectiveness and safety of chloral hydrate sedation i n children of various ages. SUBJECTS AND METHODS. The study included 3 00 infants and children, 1 month to 11 years old (mean, 3 years), who were given oral chloral hydrate, 100 mg/kg, for sedation before MR ima ging. The maximum total dose administered was 2.5 g, which limited the study to children who weighed 25 kg or less. Sedation was considered successful when MR studies were completed and at least 95% of the imag es had little or no motion artifact. RESULTS. Sedation was successful in 273 (91%) of 300 children. It was unsuccessful in nine of the 203 c hildren who were 48 months old or younger (96% success rate) and in 18 of the 97 children who were more than 48 months old (81% success rate ). A single-tailed t-test showed that the children in whom sedation wa s unsuccessful were significantly older than those in whom it was succ essful to the .0005 level of significance. The failure rate increased steadily for children more than 48 months old. Several failures may al so have resulted from lengthy examination times. Adverse reactions to chloral hydrate sedation included hyperactivity (6%), vomiting (4%), a nd mild respiratory depression (4%). No adverse reaction was severe en ough to require hospitalization. CONCLUSION. The higher failure rate f or chloral hydrate sedation in children more than 48 months old sugges ts that the patient's age is an important limitation to the usefulness of chloral hydrate sedation for children undergoing MR imaging. Howev er, the low rate of adverse reactions makes chloral hydrate a safe dru g for sedation of children undergoing MR imaging.