Efficacy of pre-incisional bupivacaine infiltration on postoperative pain relief after appendectomy: prospective double-blind randomized trial.

Pain is the most undesirable and threatening experience for surgical patients. This study aims to determine the efficacy of pre-incisional analgesic bupivacaine infiltration (preemptive analgesia) on postoperative pain relief after appendectomy. A prospective randomized double-blinded study was conducted on 123 patients aged 13-45 years with a preoperative and-postoperative diagnosis of acute appendicitis admitted to Siriraj Hospital, Bangkok, from January to May 2002. They were randomly set into two groups: the control (61 patients) and the preemptive (62 patients). In the preemptive group, bupivacaine (Marcaine) was infiltrated into the skin and subcutaneous tissue along the proposed wound line before gridiron incision, and also into the muscle layer after incision. The control group received no injection. Routine appendectomy was done. Pain score was assessed by the patients in the first 48 hr while they were lying supine and as they moved to a sitting position at 24 and 48 hr after operation. Morphine injection was given on patients' request with pain score = 5 every 4 hr in the first 48 hr or until analgesic paracetamol could be taken orally. The pain score during the first 6, 12, 24, and 48 hr, including the score while sitting up, were all significantly lower ( p < 0.001) in the preemptive group. So were the total number of morphine injections and the amount of morphine used postoperatively. The pain reduction could be due to interruption of inflammatory or pain mediator cascades that normally occur during an operation. This study showed that pre-incisional bupivacaine infiltration is an effective and simple method of reducing postoperative pain for patients undergoing appendectomy.