Intrathecal Morphine: Dosage and Efficacy in Younger Patients for Control of Postoperative Pain Following Spinal Fusion

Abstract

Intrathecal morphine in an average dose of 0.01 mg/kg was given to 33 patients between ages 11 and 16 years who had spinal arthrodesis for idiopathic scoliosis. The morphine was administered intrathecally as a 10-cc bolus at the conclusion of the arthrodesis, but before closure. The goal was to study safety in terms of respiratory depression and pain relief Respirations occurred spontaneously in 30 of the 33 patients within 15 minutes of cessation of anesthesia. Respiratory depression occurred in five patients, four of whom had arterial blood pC02 levels >60 mm Hg. Thirty-one patients had relief of pain for 8 to >40 hours, averaging 18 hours. Two patients had no noticeable pain relief There appeared to be no relation between dose and pain relief in this limited dose range. We were unable to duplicate the long duration of pain relief reported elsewhere. We also were unable to decrease the side effects of respiratory depression and nausea to a level reported by others. It may be that the 10 cc bolus injected intrathecally circulates to the brain and ventricles faster than desired, or that factors relating to type of anesthesia or dose need to be considered. Low-dose intrathecal morphine does provide noticeable pain relief in younger patients undergoing spinal fusion. The side effects of nausea and respiratory depression can be managed safely with medication.

Nausea and Vomiting After Posterior Spinal Fusion in Adolescent Idiopathic Scoliosis

“…any PONV-lowering strategy by reducing opioid consumption through modifying administration techniques, altering routes of administration, and adjusting dosing regimens reported 22,23,28,29,35,73,74 . However, we noted a trend toward lower PONV rates when epidural analgesic methods were used without combination 28,75 , lower opioid dose administration 25,27,28,76 , and with subcutaneous/epidural analgesic route [75][76][77] . Nonpharmacological measures such as the use of chewing gum has shown to reduce PONV in laparoscopic or breast surgery 78 .…”

Safety and efficacy of intrathecal morphine in early onset scoliosis surgery

“…Milbrandt et al [11] performed a retrospective study comparing PCA, EPI and IM for pain management in patients with adolescent idiopathic scoliosis undergoing PSF and found all three to be well-tolerated, although transient neurologic changes were seen in 20% of patients in the EPI group. While numerous studies have shown IM to be effective and well-tolerated in patients with adolescent idiopathic scoliosis undergoing PSF and SSI, none of these have examined the use of IM in children with EOS undergoing initial growing rod instrumentation or final fusion [5][6][7][8][9][10][11][12][13][14][15]. The purpose of this study was to determine if a single preincision dose of IM can be used in a well-tolerated and effective manner for postoperative pain control in patients with EOS undergoing initial instrumentation and final PSF and SSI.…”

“…There is variation in the dosing of intrathecal morphine for spine surgery in children, ranging from 2 to 20 mcg/kg in published reports [5][6][7][8][9][10][11][12][13]15]. We have used a dose of 9-19 mcg/kg up to 1 mg through the full duration of the study period.…”

“…Intrathecal morphine (IM) is a popular adjunct for pain management in pediatric spinal deformity surgery. Multiple studies in patients with idiopathic scoliosis have demonstrated that IM can provide well-tolerated and effective analgesia in the immediate postoperative period regardless of patient race or sex when used in a range of 9-19 µg/kg with a mean of 15 µg/kg [5][6][7][8][9][10][11][12][13][14][15]. This paradigm of IM dosing at 9-19 µg/kg with a mean of 15 µg/ kg has been our recommended dosing regimen based on this prior literature.…”