NM-329
The effectiveness of intrathecal morphine compared to intravenous methadone for postoperative pain control after posterior spinal fusion for adolescent idiopathic scoliosis
Lee H, Cronin J, Gordish-Dressman H, Martin B, Otgen M, Thomson K, Pestieau S
Children's National Medical Center, Washington, DC, United states
Purpose: There are no universally accepted protocols for perioperative pain management of patients with adolescent idiopathic scoliosis (AIS) undergoing posterior spinal fusion (PSF). At our institution, as part of the initiation of a perioperative surgical home (PSH) for AIS, a multidisciplinary group implemented evidence-based protocols for the perioperative care of these patients. Our pain pathway includes an intrathecal (IT) injection of morphine by the anesthesiologist prior to surgical positioning, and a standardized intraoperative and postoperative regimen of analgesics When the IT injection of morphine is technically challenging, contraindicated or unavailable, methadone is given IV intraoperatively and in the immediate postoperative period. Here, we compare these 2 analgesic modalities and their impact on pain related outcomes.
Methods: The PSH was implemented in March 2015. Charts of patients enrolled in the PSH were retrospectively reviewed through July 2017. Operative and postoperative data for patients who received a single IT morphine injection were compared to patients who received IV methadone. Operative variables included surgical time, non-surgical time, intraoperative crystalloid and transfusion requirements. Postoperative variables included highest and average daily pain score, opioid and diazepam use, and opioid-induced side effects as measured by the need for anti-emetic and antipruritic medications.
Results: A total of 190 patients were included with 142 receiving IT morphine and 48 receiving methadone. The mean dose of morphine was 8.5 mcg/kg. Methadone was given as 0.2mg/kg with induction, followed by 2 doses of 0.1mg/kg every 6 hours. There were no complications from the IT injection. There was no difference in surgical time, non-surgical operating room time, crystalloid or albumin use, cell saver or intraoperative blood transfusion. Patients who received IT morphine had significantly lower average pain scores on postoperative day 0 (POD 0), compared to those treated with methadone (3 vs. 4.3, p<0.001). The highest pain score on POD 0 and POD 2 were also significantly lower with IT morphine (5.6 vs. 7, p=0.006 and 6.7 vs. 5.9, p=0.035), but these patients used more cumulative doses of nalbuphine and promethazine postoperatively (0.32 vs. 0.13, p=0.028 and 0.14 vs. 0.02, p=0.06).. There was no difference in length of stay, postoperative daily morphine equivalents, or the use of diazepam, diphenhydramine and ondansetron between the 2 groups. There was no relationship between the dose of IT morphine, postoperative pain scores and use of ondansetron, promethazine, or nalbuphine, but higher morphine doses were associated with increased diphenhydramine requirement on POD 0 and 2 (p=0.016 and p=0.033).
Conclusion: As part of a standardized clinical pathway for patients with AIS undergoing PSF, IT morphine provides better analgesia on postoperative day 0 and 2 compared to methadone. However these patients required more antiemetic and antipruritic medications. Lower doses of IT morphine achieved the same pain outcomes as higher doses, and also decreased diphenhydramine requirements. Lastly the IT injection did not increase OR time.
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