A comparison of epidural ropivacaine infusion alone and in combination with 1, 2, and 4 μg/mL fentanyl for seventy-two hours of postoperative analgesia after major abdominal surgery

Our aim in this prospective, randomized, double-blinded study was to compare the analgesic effectiveness and side effects of epidural infusions with ropivacaine 2 mg/mL alone (Group R; n = 60) and in combination with fentanyl 1 mu g/mL (R1F; n = 59), 2 mu g/mL (R2F; n = 62), and 4 mu g/mL (R4F; n = 63) for up to 72 h after major abdominal surgery. Effective epidural neural blockade was established before surgery; postoperatively, the infusion rate was titrated to a maximum of 14 mL/h for analgesia. No additional analgesics other than acetaminophen were permitted during the infusion. The median of individual visual analog scale score with coughing were <20 mm for all groups (0 = no pain, 100 = worst pain) and was significantly lower (P < 0.01) for Group R4F at rest and with coughing (compared with Group R). Infusions were discontinued due to inability to control pain in significantly fewer patients in Group R4F (16%) than the other groups (34% to 39%; P < 0.01). For all groups, >90% of patients had no detectable motor block after 24 h. Hypotension, nausea, and pruritus were more common with the larger dose of fentanyl. We conclude that, after major abdominal surgery, an epidural infusion of ropivacaine 2 mg/mL with fentanyl 4 mu g/mL provided significantly more effective pain relief over a 3-day period than ropivacaine alone or ropivacaine with lower concentrations of fentanyl. Implications: Postoperative epidural analgesic infusions are widely used, but there is little information regarding optimal strengths of opioid with local anesthetic. In this blinded, prospective study, we compared four different epidural infusion solutions for efficacy and side effects over a clinically useful postoperative period and conclude that an epidural infusion of ropivacaine 2 mg/mL with fentanyl 4 mu g/mL was most effective.