Sixty patients took part in a randomised, double-blind study to compar
e the analgesic and side effects of three opioid-containing solutions
for patient-controlled epidural analgesia following abdominal surgery.
Patients in group 1 received a solution containing bupivacaine 0.125%
with fentanyl 10 mu g.ml(-1), group 2 bupivacaine 0.125% with diamorp
hine 125 mu g.ml(-1), group 3 pethidine 2.5 mg.ml(-1). All groups rece
ived 4 ml.h(-1) background infusion and 3 ml boluses every 20 min if n
ecessary. There were no significant differences between the groups in
visual analogue scale pain scores (p=0.537) or volumes of solution use
d at 24h (p=0.351) or 48h (p=0.105). Motor block was significantly hig
her in group 2 (p<0.004) and pruritis occurred significantly less in g
roup 3 (P<0.05). We conclude that these three solutions produce equiva
lent analgesia but that pethidine 2.5 mg.ml(-1) may be associated with
fewer side effects.