Transdermal Buprenorphine versus Intramuscular Diclofenac for Postoperative Analgesia following Upper Abdominal Surgery under General Anesthesia: A Randomized Controlled Trial

Aim: To compare the post-operative analgesic effect of of buprenorphine 20 µg/h patch with diclofenac 75 mg intramuscular injection following upper abdominal surgery under general anesthesia (GA). Materials and Methods: An open‑label, randomized, controlled trial (CTRI/2018/03/012694) was conducted with adult subjects of either sex, undergoing planned major upper abdominal surgery under GA. Preoperative medication regimen and anesthesia protocol were uniform for all patients. Buprenorphine patch was applied to a hairless area of the chest or upper arm 12 h before surgery. Diclofenac 75 mg was injected into the deltoid muscle just after extubation. Postoperatively, vital signs were monitored along with Ramsay sedation scale (RSS) score. Postoperative analgesia was assessed using visual analog scale (VAS) scoring, at 4‑h interval for the first 12 h and then 12‑hourly for the next 2 days. Tramadol 2 mg/kg intravenous was permitted as a rescue analgesic. Results: Each arm had 35 patients without dropouts. The groups remained comparable in VAS pain score at all time points. However, with buprenorphine, although VAS score declined over time, the reduction attained statistical significance in comparison to the baseline (4 h) VAS score only at 72 h. In contrast, with diclofenac, VAS score achieved statistically significant reduction from 8 h onward and this was maintained throughout. In the buprenorphine arm, 21 patients (60.00%) required rescue analgesia in contrast to 10 (28.57%) on diclofenac (P = 0.016). Vital parameters and RSS remained essentially unchanged in both groups. Conclusion: Although the primary outcome measure was comparable between the groups, the pattern of rescue analgesia use suggests that postoperative analgesia experience with buprenorphine patch was less satisfactory than diclofenac injection in this study.