A prospective randomized pragmatic double-blinded comparison of 0.125% and 0.0625% bupivacaine for the management of pain after operation in patients undergoing major abdominal surgery

Background: The aim of this prospective, pragmatic, double-blind, randomized controlled trial was to investigate the analgesic and adverse effects of two concentrations of thoracic epidural bupivacaine in patients undergoing major abdominal surgery. Our primary aim was to reduce the incidence of hypotension resulting from effective epidural analgesia.Methods: We studied 100 patients who were randomized to receive either 0.0625% bupivacaine or 0.125% bupivacaine, both with diamorphine, via a thoracic epidural. Dynamic pain was measured using a verbal ranking score and visual analogue scores.Results: No statistically significant difference was found between infusion rates or dynamic pain scores. A significantly greater number of patients receiving 0.125% bupivacaine, 63% versus 39%, were hypotensive on the day of surgery (p = 0.027). Thereafter, the trend continues but was not statistically significant.Conclusion: We were able to demonstrate that the incidence of hypotension was reduced with 0.0625% bupivacaine without affecting the quality of pain relief. However the overall incidence of hypotension remained high which restricted early mobilisation in some patients. Hypotension may be unavoidable when epidurals effectively control postoperative pain