Postoperative pain relief by topical lidocaine in the surgical wound of hysterectomized patients

Background: To improve postoperative analgesia, local anesthetics have been administered perioperatively as infiltration or as aerosol in the surgical area. A previous study showed good analgesic effects by topical lidocaine in the wound in minor extraabdominal surgery (herniorraphy), while the same treatment in minor lower laparothomies did not improve postoperative analgesia. The present study investigated the effect of topical wound anesthesia using lidocaine aerosol on postoperative pain following major lower abdominal surgery. Methods: Postoperative pain and analgesic requirements were studied in a double-blind randomized trial including 30 hysterectomized patients. Patients were randomized to receive single wound treatment either with lidocaine aerosol 500 mg (100 mg/ml; Xylocain(R) aerosol, ASTRA, Sweden) (n=15) or placebo aerosol (n=15). Postoperative pain was evaluated by visual analogue scale (VAS). Requirements of opiate analgesics (buprenorphine) after surgery were monitored. Results: Lidocaine aerosol induced a significantly (P<0.001) better analgesia at rest (VAS) and a significant (P<0.001) reduction in postoperative requirements of buprenorphine during the first 24 hours after surgery compared to placebo aerosol. Differences between the groups in pain scores (VAS) and buprenorphine requirements during the second postoperative day were not significant. Mean pain scores upon mobilization 24 h after surgery were significantly lower in the group receiving Lidocaine aerosol (P<0.05). The plasma lidocaine concentration 4 h after the administration of lidocaine was well below toxic level and plasma lidocaine was detectable 48 h postoperatively. No drug-related side effects were reported. Conclusion: A single dose of Lidocaine aerosol topically administered in the surgical wound of hysterectomy patients improved analgesia during the first postoperative day with minimal risk of side effects.