Intrathecal Morphine Versus Extended-Release Epidural Morphine for Postoperative Pain Control in Pediatric Patients Undergoing Posterior Spinal Fusion.

BACKGROUND: Posterior spinal fusion for scoliosis is one of the most painful elective pediatric surgeries. Good postoperative pain control allows early ambulation and return of ability to tolerate oral intake. Options for analgesia in this patient population are suboptimal. We hypothesized that extended-release epidural morphine (EREM) would provide better pain control and less adverse effects compared to intrathecal (IT) morphine.

METHODS: The primary outcome was total IV morphine consumption during 0-48 hours postoperatively. Secondary outcomes included time until first patient-controlled analgesia (PCA) demand, pain scores, and adverse opioid effects. After institutional review board approval, 71 subjects undergoing posterior spinal fusion for idiopathic scoliosis completed the study. The subjects were randomly allocated to 7.5 μg/kg IT morphine or 150 μg/kg EREM. The final IT morphine and EREM groups contained 37 and 34 subjects, respectively. Postoperative pain was treated with morphine PCA, ketorolac, oral oxycodone, and acetaminophen. Morphine consumption, pain scores, nausea and vomiting, pruritus, and respiratory depression were measured every 4 hours. Parents completed a caregiver questionnaire about their child's pain control regimen after the first postoperative day.

RESULTS: There was no difference in total morphine consumption over the first 48 hours between subjects in the EREM and IT morphine groups: median (range) 42.2 (5.5-123.0) and 34.0 (4.5-128.8) mg, respectively (P = .27). EREM and IT morphine groups had no difference in time until first PCA demand. Pain scores were no different between the groups from 8 to 24 hours after surgery. Compared to IT morphine, EREM subjects had lower pain scores from 28 to 36 hours after surgery. The reported incidence of pruritus was lower in the EREM subjects.

CONCLUSIONS: There was no difference in total morphine consumption or time until first PCA demand between the EREM and IT morphine groups. EREM provides a longer duration of analgesia after posterior spinal fusion for scoliosis and may be associated with less opioid-induced pruritus.