Postoperative Analgesia in Lumbar Discectomy: Morphine vs. Dexamethasone-Soaked Epidural Gelfoam: A Randomized Controlled Trial

Abstract This study compared the analgesic efficacy of gelfoam-soaked epidural morphine with gelfoam-soaked epidural dexamethasone following lumbar discectomies as their clinical comparison is lacking. Sixty patients undergoing single-level lumbar discectomy surgeries were randomized either in group M (gelfoam-soaked epidural morphine, 3 mg) or in group D (gelfoam-soaked epidural dexamethasone, 8 mg) placed over the duramater before the closure. The primary objective was to compare the mean time to first rescue analgesia for 24 postoperative hours. The secondary objectives were pain intensity, total rescue analgesic requirement, and to look for any adverse event related to study drugs. The primary outcome was analyzed using a two-tailed unpaired t-test as well as a Cox proportional hazards model. The categorical outcome of complete response was compared using a chi-squared test. The other numerical outcomes were compared using a linear mixed effects model accounting for repeated measures and the categorical repeated measure outcome was evaluated using a binomial generalized estimating equations model. The mean time to first analgesic (hours) in both the groups (M vs. D, 26 [12] vs. 19 [6], mean difference = 7 [95% confidence interval [CI], −8.2, 22, p = 0.3, unpaired t-test) was not significant. The pain scores showed a tendency toward low pain scores at 24 hours in the morphine group. The sedation scores and number needing rescue analgesia did not differ between groups. Pain scores and the number needing rescue analgesia decreased significantly in both groups over time. There was a difference in terms of complete response between the groups (M vs. D, 83% vs. 57%, difference of 27% [95% CI of 1.1%, 52%], p = 0.02, chi-square test). Gelfoam-soaked epidural morphine versus dexamethasone demonstrated no difference in mean time to first rescue analgesic following lumbar discectomy surgeries but gelfoam-soaked epidural morphine reduced the requirement of rescue analgesia in the first 24 postoperative hours compared with gelfoam-soaked epidural dexamethasone.