Can pre-emptive lumbar epidural blockade reduce postoperative pain following lower abdominal surgery?

In a double-blind study, 36 patients who received a standard general anaesthetic for abdominal hysterectomy or myomectomy, received either 15 ml of bupivacaine 0.5% with adrenaline by lumbar epidural injection 15 min before surgery (group A) or the same dose at the end of surgery but before waking (group B). Pain was assessed for 24 h by cumulative morphine dose (self-administered by patient-controlled analgesia), visual analogue scale and verbal rating score. Patients were included for analysis if they were pain free on waking and for at least 2 h after. There was no significant difference (p > 0.05) between the two groups in morphine dose, visual analogue scale or verbal rating score at 6 and 24 h after waking. As expected, there was a significant difference in the mean time of first use of patient-controlled analgesia (4.26 h in group A vs 5.06 h in group B, p < 0.05). Consequently, we compared the morphine dose, visual analogue scale and verbal rating score at 23 h in group A with those at 24 h in group B. Again there were no significant differences between the two groups. We were unable to demonstrate that epidural blockade had a significantly better effect on postoperative pain when administered before, rather than after, surgery.