Wound perfusion with bupivacaine: objective evidence for efficacy in postoperative pain relief

Conflicting reports exist for the efficacy of intermittent wound perfusion with bupivacaine in the relief of postoperative pain. A study was devised to assess postoperative pain relief objectively using a Patient Controlled Analgesic Device (PCAD) during continuous wound perfusion with bupivacaine or saline. Thirty consecutive patients undergoing cholecystectomy were randomised to receive continuous postoperative wound perfusion with 0.5% bupivacaine for 24 h followed by normal saline for a further 24 h or vice versa. During the study period, conventional analgesia was provided using a PCAD set to deliver (and record the number of) on-demand bolus doses of intravenous pethidine 0.2 mg/kg at half-hourly intervals as required. Pethidine requirements were higher on the first postoperative day, regardless of which solution was given, but bupivacaine perfusion almost halved mean linear analogue pain scores compared to those recorded with saline. Likewise, the number of bolus doses of pethidine demanded was reduced by an average of 68% compared to those recorded during saline perfusion on day 1 (P = 0.01) and by 82% on day 2 (P = 0.01). When assessed by objective criteria, perfusion of surgical wounds with bupivacaine after cholecystectomy produces better pain relief than wound perfusion with saline.