[Postoperative epidural analgesia after upper abdominal surgery: the effects of low concentrations of bupivacaine combined with a low dose of opioid]

Abstract

The efficacy and safety of postoperative analgesia with continuous epidural infusion of either morphine or fentanyl in combination with a low dose of bupivacaine were evaluated in 205 patients after upper abdominal surgery. Each patient was given bupivacaine alone (0.125% or 0.25%) or one of six combinations; 0.25%, 0.125%, or 0.0625% bupivacaine with morphine (M: 10 micrograms.ml-1) or fentanyl (F: 1 microgram.ml-1). After injection of 6 ml of each solution at the end of surgery, continuous epidural infusion was started at a rate of 4.2 ml.hr-1 for 48 hr. The degree of pain relief was assessed by the necessity of supplementary analgesics, the visual analogue pain scale and the Prince Henry pain scale. The most effective analgesic situation was obtained with the 0.25% M and the 0.25% F groups. The 0.125% M and 0.125% F groups showed adequate analgesia for elderly patients with few side effects. Regarding the plasma catecholamines measured 24 hr after the surgery, there was no significant change in fentanyl groups as well as in the group given 0.125% bupivacaine alone. Although the incidence of hypotension and pruritus was slightly higher in morphine groups, no patient developed respiratory depression. It is suggested, therefore, that a small dose of opioid should be added when continuous epidural infusion is required.