Is wound infiltration with anesthetic effective as pre-emptive analgesia? A clinical trial in appendectomy patients

abstract

OBJECTIVE: To assess the efficacy of wound infiltration with local anesthetic in reducing postoperative pain after a muscle-splitting incision for appendectomy. DESIGN: A double-blind, placebo-controlled, randomized clinical trial. SETTING: The Royal Columbian Hospital, a university-affiliated community hospital. PARTICIPANTS: Forty-three patients scheduled to undergo emergency appendectomy were randomized into treatment (21) and control (22) groups. Five patients were excluded from the treatment group. INTERVENTIONS: Local anesthetic infiltration of the wound before incision (treatment group) and saline infiltration (control group). MAIN OUTCOME MEASURES: Postoperative analgesic requirements, pain assessment by visual analogue scale and length of hospital stay. RESULTS: No significant difference in analgesic use was seen between the 2 groups, as measured at 3 stages (Mc = control mean [standard deviation], Mt = treatment mean [standard deviation]): (a) in the recovery room, intravenous morphine use was Mt = 6.6 mg [8.6] v. Mc = 10.1 mg [7.2]; (b) in the first 2 postoperative days, intramuscular meperidine use was Mt = 309 mg [181] v. Mc = 278 mg [125] on day 1 and was Mt = 121 mg [132] v. Mc = 97 mg [128] on day 2; (c) in the final 5 days of follow-up, oral analgesic use was Mt = 11 [17] tablets v. Mc = 21 [16] tablets (acetaminophen with codeine). Pain assessments at rest, on a scale of 1 to 10, were found to be no different between groups, ratings being Mt = 4.7 [2.1] v. Mc = 4.5 [2.0] on day 1. Length of hospital stay averaged 3.0 days in both groups. CONCLUSIONS: Infiltration with local anesthetic before incision does not pre-empt postoperative pain from a muscle-splitting incision used for appendectomy.