Intrathecal morphine for postoperative pain relief in children.

Intrathecal morphine was given to 56 children undergoing open-heart surgery. The first 27 patients received 0.03 mg kg-1 and the other 29 received 0.02 mg kg-1. Satisfactory postoperative analgesia, lasting for 22 h or longer, was obtained in over 60% of the patients in each group. Respiratory depression occurred in six of the first group (0.03 mg kg-1), and three in the second (0.02 mg kg-1), most frequently between 3.5 and 4.5 h after the administration of the intrathecal morphine.