Does adrenaline improve epidural bupivacaine and fentanyl analgesia after abdominal surgery?

The alpha-adrenergic agonists have been demonstrated to have synergistic effects with opioids and local anesthetics in animal research. The present study was performed to determine whether the addition of adrenaline improves the analgesic effects of an epidural infusion of a combination of fentanyl and bupivacaine after abdominal surgery. We studied 90 ASA 1 or 2 patients scheduled for abdominal surgery under epidural anaesthesia, with or without general anaesthesia. Patients were randomly divided into two groups to receive a postoperative epidural infusion of fentanyl 5 micrograms/ml in bupivacaine 0.2%, with or without adrenaline 5 micrograms/ml, at a rate of 2 ml/h for more than 48 hours. Postoperative pain relief was assessed using visual analog scales (VAS), both at rest and during coughing, at 2, 24, and 48 hours after surgery. The number of rescue analgesics and side-effects such as nausea, vomiting, pruritus, respiratory depression, headache, muscle weakness, and hypotension were recorded. Patients who received adrenaline (n = 40) reported significantly lower mean VAS scores than those who received no adrenaline (n = 37), both at rest at 24 hours postoperatively and during coughing at 24 and 48 hours. The number of additional analgesics and incidence of side-effects did not differ between groups. In conclusion, the results of the present study demonstrate that the addition of adrenaline to a combination of fentanyl and bupivacaine improves the quality of epidural analgesia after abdominal surgery. Under the conditions of the study, we did not detect any disadvantage from the addition of adrenaline.