202. INTRATHECAL MORPHINE ANALGESIA IN IDIOPATHIC SCOLIOSIS SURGERY: DOES GENDER OR RACIAL GROUP AFFECT OPTIMAL DOSING?

Abstract

Purpose: Do children from different gender or racial groups receive different analgesic doses for the same acute pain condition? We previously reported on intra-thecal morphine for preemptive analgesia in children undergoing posterior spinal fusion (PSF) and segmental spinal instrumentation (SSI) for idiopathic scoliosis (IS). We determined the optimal dose range to maximize analgesia while minimizing adverse effects. The purpose is to ensure this adopted protocol is equally effective across gender and racial groups.

Method: We studied 407 intrathecal morphine patients. Those given a moderate dose of 9–19 mcg/kg (n=293) had the most effective and safe postoperative pain relief. This group consisted of 246 female and 47 male patients. There were 224 Caucasian (CA) and 63 African-American (AA) patients. Other ethnicities were excluded. Factors analyzed included postoperative Wong-Baker visual analog pain scores (VAS), time to first opioid rescue dose, total morphine dose over the first 48 hours, and postoperative complications.

Results: For female and male gender, mean VAS pain scores in post-anesthesia care unit (PACU) were 0.48 and 0.56, mean times to first opioid rescue dose were 999.1 and 1003.3 minutes, and total morphine over the first 48 hours were 1.5mg/kg in both groups, respectively. Respiratory depression and PICU admission occurred in 2 (4.2.%) and 4 (1.6%) patients, respectively. For CA and AA patients, mean VAS pain scores in PACU were 0.48 and 0.46, mean times to first opioid rescue dose were 991.7 and 1031.9 minutes, and total morphine over the first 48 hours were 1.5mg/kg and 1.3mg/kg, respectively. Respiratory depression occurred in 5 (2.2.%) and 2 (3.2%) patients and PICU admission occurred in 4 (1.8.%) and 4 (6.3%) patients, respectively. StudentÂ’s t-test and Fisher exact test demonstrated no significant differences between genders for all variables, and no significant differences between races except less total morphine for AA patients over the first 48 hours (p=0.0024).

Conclusion: An optimal intrathecal morphine dose range of 9–19 mcg/kg provides effective and safe postoperative pain relief in children undergoing PSF and SSI for IS, regardless of gender or race. Intrathecal morphine can be given with the assurance that it does not discriminate against gender or provide less optimal analgesia to AA patients.