Fig. 1. The duration of analgesia for each patient during the 6-h observation period in the recovery room (dark gray columns), and the 18-h observation period at the ward (light gray columns). Numeric values are presented as median (range). Caudal = caudal administration of S  (+)-ketamine; I.M. = intramuscular administration of S  (+)-ketamine. *Values for the caudal group were significantly different from the other group.