Postoperative analgesia in children: a prospective study in intermittent intramuscular injection versus continuous intravenous infusion of morphine.

Few advancements in postoperative pain control in children have been made despite longstanding inadequacies in conventional intramuscular analgesic regimens. While overestimating narcotic complication rates, physicians often underestimate efficacious doses, nurses are reluctant to give injections, and many children in pain shy away from shots. This study prospectively focuses on the safety, efficacy, and complication rate of intermittent intramuscular (IM) versus continuous intravenous infusion (IV) of morphine sulfate (MS) in 46 nonventilated children following major chest, abdominal, or orthopedic surgical procedures. Twenty patients assigned to the IM group had a mean age of 6.17 years and a mean weight of 23.0 kg. Twenty-six patients assigned to the IV group had a mean age of 8.74 years and a mean weight of 27.4 kg. The mean IM MS dose was 12.3 micrograms/kg/h while the mean IV dose was 19.8 micrograms/kg/h (P less than .001). Postoperative pain was assessed with a linear analogue scale from 1 to 10 (1, "doesn't hurt"; 10, "worst hurt possible") for 3 days following operation. Using the analysis of covariance (ANACOVA), nurse, parent, and patient mean pain scores in the IV group were significantly lower than those of the IM group when controlled for age, MS dose, and complications (P less than .007). Nurse assessment of pain correlated well with the patient and parent assessments (Pearson correlation coefficients greater than 0.6). Not only did IV infusion give better pain relief than IM injections, but there were no major complications such as respiratory depression. Minor complications in this study (nausea, urinary retention, drowsiness, vomiting, hallucinations, lightheadedness, and prolonged ileus) were not significantly different between IM and IV groups.(ABSTRACT TRUNCATED AT 250 WORDS)