Does the combination of intrathecal fentanyl and morphine improve clinical outcomes in patients undergoing lumbar fusions?

Abstract

Intrathecal morphine (ITM) has been widely effective in improving postoperative outcomes in patients undergoing a multitude of surgeries, including lumbar spine fusion. A major limitation of ITM administration is the increase in the incidence of respiratory depression in a dose-dependent manner. One way to bypass this is to use a more potent opioid with a shorter half-life, such as fentanyl. This is a retrospective analysis of patients who underwent one- or two-level transforaminal lumbar interbody fusions. The patients received one of two interventions: 0.2mg intrathecal duramorph/morphine (ITM group; n=70), 0.2mg duramorph + 50 mcg fentanyl (ITM + fentanyl group; n=68) and the control group (n=102). Primary outcomes included postoperative pain (Visual Analog Scale) and opioid intake (MED - morphine equivalent dosage, mg) for postoperative days (POD) 1- 4. Secondary outcomes included opioid-related side effects. One-way analyses of variance and follow-up post-hoc Tukey's honest significant difference statistical tests were used to measure treatment effects. Significantly lower POD1 pain scores for both the ITM and ITM + fentanyl groups vs. control were detected, with no difference between the ITM vs. ITM + fentanyl groups. Similar results were found for POD1 MED intake. A multivariate regression analysis controlling for confounding variables did not attenuate the differences seen in POD1 pain scores while revealing that only the ITM + fentanyl predicted a decrease in POD1 MED intake. No differences were seen for postoperative opioid-related side effects. Our study provides support for supplementing a low dose of both intrathecal morphine and fentanyl to improve postoperative outcomes.