Intrathecal morphine analgesia in idiopathic scoliosis surgery: does sex or racial group affect optimal dosing?

Abstract

We previously determined the intrathecal morphine optimal dose to maximize analgesia in patients undergoing idiopathic scoliosis surgery while minimizing adverse effects. Our purpose was to determine if this protocol was equally effective across sex and racial groups. We studied 287 patients given a moderate dose of intrathecal morphine of 9 to 19 μg/kg (mean 14 μg/kg): 240 female and 47 male patients and 224 White (W) and 63 African-American (AA) patients. Factors analyzed included postoperative visual analog pain scores (VAS), time to first opioid dose, total morphine over the first 48 hours, and postoperative complications of respiratory depression requiring pediatric intensive care unit (PICU) admission, nausea/vomiting and pruritis. For female and male patients, mean VAS pain scores in postanesthesia care unit (PACU) were 0.48 ± 1.14 and 0.56 ± 1.16, mean times to first opioid dose were 16.65 ± 4.38 and 16.72 ± 4.97 hours, and total morphine over the first 48 hours were 1.49 ± 0.53 and 1.49 ± 0.58 mg/kg, respectively. Respiratory depression and PICU admission occurred in 10 of 240 female (4.1%) and 3 of 47 male (6.4%) patients. Minor complications of nausea/vomiting and pruritis occurred in 78 of 240 female (31.7%) and 12 of 47 male (25.5%) patients. For W and AA patients, mean VAS pain scores in PACU were 0.48 ± 1.10 and 0.46 ± 1.13, mean times to first opioid dose were 16.53 ± 3.77 and 17.12 ± 6.05 hours, and total morphine over the first 48 hours were 1.54 ± 0.53 and 1.30 ± 0.53 mg/kg, respectively. Respiratory depression and PICU admission occurred in 9 of 224 W (4.0%) and 4 of 63 AA (6.3%) patients. Nausea/vomiting and pruritis occurred in 77 of 224 W (34.4%) and 11 of 63 AA (17.5%) patients, respectively. Intrathecal morphine results in safe and effective for postoperative pain relief in patients undergoing surgery for idiopathic scoliosis irregardless of sex or race. III, retrospective comparative study.