204. CONTINUOUS INTRAVENOUS MORPHINE INFUSION FOR POSTOPERATIVE ANALGESIA FOLLOWING POSTERIOR SPINAL FUSION FOR IDIOPATHIC SCOLIOSIS

Abstract

Purpose: Postoperative pain is common following posterior spinal fusion (PSF) and segmental spinal instrumentation (SSI) for idiopathic scoliosis (IS). It is often treated with intravenous morphine patient controlled analgesia (PCA), but no studies have examined continuous morphine infusion. The purpose of this study was to identify the safety and efficacy of continuous morphine infusion without PCA for post-operative pain management in these patients.

Method: We retrospectively reviewed 338 consecutive patients from 1992 to 2006 who received continuous morphine infusion. Following induction of general anesthesia and prior to surgical incision, patients received intrathecal morphine for preemptive analgesia. Anesthesia was maintained with 50% nitrous oxide and up to 0.6% isoflurane, with minimal or no intravenous opioids. Following surgery, pre-ordered morphine infusion (0.01 mg/kg/hr) began when patients first reported pain. The infusion rate was titrated using a strict protocol based on frequent assessment of vital signs, Wong-Baker visual analog pain scores (VAS), and clinical status. The infusion continued until patients were able to take oral analgesics at postoperative day 2–3. Factors analyzed included patient demographics, intrathecal morphine dosage, intraoperative intravenous opioid dosage, pain scores through the third postoperative day, interval to start of morphine infusion, total morphine requirement in the first 48 postoperative hours, and postoperative complications.

Results: Mean intrathecal morphine dose was 15.45 mcg/kg and mean interval to start of morphine infusion was 15:45 hours. Mean VAS pain scores were 3.05, 4.48, 4.48, and 4.60 at 12 hours, 1, 2, and 3 days postoperatively. The total mean dosage of morphine in the first 48 hours postoperatively was 0.03 mg/kg/hr. Nausea/vomiting, pruritis, respiratory depression, and PICU admissions related to the morphine drip occurred in 13.3%, 4.1%, 0%, and 0% of the patients during the same time period.

Conclusion: A low frequency of adverse events and a mean postoperative pain score of 5 or less demonstrates that continuous postoperative morphine infusion is a safe and effective method of pain management in children following PSF and SSI for IS. Continuous morphine infusion without PCA is a safe, alternative method of pain control for postoperative patients with IS.