Postoperative Epidural Fentanyl Infusion—is the Addition of 0.1% Bupivacaine of Benefit?

Abstract

A randomised, double-blind controlled clinical trial was conducted in 90 women scheduled for major abdominal gynaecological oncology surgery to determine the effect of adding 0.1% plain bupivacaine to a thoracic epidural fentanyl infusion. Following combined epidural and general anaesthesia, patients were randomised to receive epidural fentanyl 10 μg/ml, with (group FB) or without (group F) bupivacaine. After an initial 50 μg bolus of fentanyl, infusion rate was adjusted according to need between 2 and 10 ml/hr for 48 hours. The two groups (n = 40) were similar with regard to age, weight and preoperative status. Analgesia both at rest and with movement were significantly better in group FB (P < 0.0001) during the first 24 hours postoperatively, the greatest difference occurring in the 4 to 16 hour period. There was no significant difference between groups from 24 to 48 hours postoperatively. Fentanyl utilisation was significantly lower in group FB (median 41 versus 53 μg/hr, P <0.001), although clinically the fentanyl dose-sparing effect of bupivacaine was small and did not reduce opioid-induced side-effects. There was no significant difference between groups with respect to side-effects or lower limb weakness, although fewer patients in group FB could be mobilised on the morning of the first postoperative day (P <0.01). Nevertherless, all study patients were ambulant by the same afternoon. We concluded that, in this patient population, the addition of 0.1% bupivacaine to a thoracic epidural fentanyl infusion was beneficial in the early postoperative period.