Timing of Intrathecal Morphine Administration and its Impact on Pain Control in Pediatric Spine Surgery.

Study design: Retrospective cohort study.

Objective: The purpose of this study is to compare outcomes of intrathecal morphine (ITM) administered preemptively versus intraoperatively, either before or after correction, in adolescent idiopathic scoliosis (AIS) patients.

Summary of background data: As a component of a multimodal pain regimen, ITM can reduce postoperative pain in pediatric patients undergoing spinal fusion, but the optimal timing of administration is unclear.

Methods: Consecutive AIS patients who underwent posterior spinal fusion at a single institution were retrospectively reviewed. Patients were either given ITM prior to incision, during exposure, or after deformity correction. Opiate consumption was measured and converted to milligram of morphine equivalents (MME).

Results: A total of 146 patients were included (85 pre-operative, 17 intraoperative before correction, and 45 intraoperative after correction). There were no statistically significant differences among groups in patient demographics or curve characteristics (P>0.05). ITM dosages were similar among groups, as were other intraoperative anesthetic infusions, including vasopressors and total intraoperative MME. There were no significant differences in operative time, blood loss, transfusion rate, or postoperative opioid consumption, including daily and total hospitalization MME (69.7 v 60.7 v 75.3, P=0.365). Hospital length of stay (2.9 v 2.8 v 2.9 d, P=0.749), potential side effects (hypotension, pruritis, nausea/vomiting), 30-day emergency department visits, and readmissions were all similar among groups (all P>0.05).

Conclusion: For AIS patients undergoing posterior spinal fusion, the timing of intrathecal morphine administration has no significant impact on perioperative pain control, functional recovery, or early outcomes. No difference in MME administration, length of stay, potential side effects (hypotension, pruritis, nausea/vomiting), or early outcomes was observed between groups. Thus, ITM can be given either pre- or intra-operatively at the discretion of the surgical and anesthetic teams.