The effect of preemptive analgesia in postoperative pain relief--a prospective double-blind randomized study.

OBJECTIVE: To analyze the effect of infiltration of local anesthetics on postoperative pain relief.

DESIGN: Prospective randomized double-blind trial. Setting. University Teaching Hospital in Barbados, West Indies.

PATIENTS: Patients undergoing total abdominal hysterectomy. Interventions. Patients were randomly allocated into one of four groups according to the wound infiltration: 1) preoperative and postoperative 0.9% saline; 2) preoperative saline and postoperative local anesthetic mixture (10 mL 2% lidocaine added to 10 mL 0.5% bupivacaine); 3) preoperative local anesthetic mixture and postoperative saline; and 4) preoperative and postoperative local anesthetic mixture. Both patients and investigators were blinded to the group allocation. All patients received pre-incision tenoxicam and morphine, standardized anesthesia, and postoperative morphine by patient-controlled analgesia. Outcome measures. The amount of morphine used and the intensity of pain as measured by visual analog pain scale were recorded at 1, 2, 3, 4, 8, 12, 24, and 48 hours postoperatively.

RESULTS: Eighty patients were studied with 20 in each group. Total dose of morphine used by patients who received preoperative and postoperative local anesthetic infiltration was lesser compared to other groups, although there was no statistically significant difference. Similarly, there was no difference in the intensity of pain between any groups.

CONCLUSIONS: Local anesthetic infiltration before and/or after abdominal hysterectomy does not reduce the intensity of postoperative pain and analgesic requirements.