Preemptive opioid analgesia does not influence pain after abdominal hysterectomy

Opioid administration before surgical stimulus may reduce or prevent subsequent pain. We studied the effect of timing of opioid administration on the pain-related behaviour after abdominal hysterectomy. Eighty-five patients scheduled for abdominal hysterectomy were blindly randomized to receive fentanyl 10 micrograms.kg-1 before induction of anaesthesia (FA), after peritoneal incision (FB) or after removal of the uterus (FC), or sufentanil 1 micrograms.kg-1 before induction of anaesthesia (SA) or after peritoneal incision (SB) respectively. All patients received a standard postoperative analgesic regimen. The time from skin closure to the first analgesic request was recorded. Pain was assessed using the VAS and a verbal rating score (VSR 1 = no pain to 6 = intolerable pain) every 30 min until patients asked for the first analgesic, and 24 hr postoperatively. The times from skin closure to the first analgesic request did not differ among the five groups. The VAS scores using the two-way ANOVA with repeated measurements differed among the five groups (F = 4.046, df = 4, 213, P < 0.005). The VAS scores with one-way ANOVA differed among the five groups 30 min postoperatively (F = 4.542, df = 4, 58, P < 0.003), being higher in the FA (6.5 +/- 1.8) and SA (5.9 +/- 2.1) groups than in the FC (3.2 +/- 2.5) group, and at 120 min postoperatively (F = 3.217, df = 4, 18, P < 0.05), being higher in the FA than in the FB group (6.1 +/- 1.5 and 2.6 +/- 1.9 respectively).(ABSTRACT TRUNCATED AT 250 WORDS)