Efficacy and safety of 5% lidocaine patches for postoperative pain management in patients undergoing unilateral inguinal hernia repair: study protocol for a prospective, double-blind, randomized, controlled clinical trial

BACKGROUND: Acute postoperative pain is a common complication of inguinal hernia repair. Pain management using local application of anesthetic agents over the skin surrounding the surgical incision may reduce the requirement for other pain medications. Targeted topical analgesics such as 5% lidocaine patches have been known to improve acute and chronic pain. However, the clinical effect of lidocaine patches on postoperative pain after inguinal hernia repair has not been studied, especially in patients undergoing surgery at day surgery units. METHODS/DESIGN: This is a single-center, prospective, double-blind, randomized, controlled clinical trial. Participants with unilateral inguinal hernia will be randomized to the lidocaine patch group or the placebo patch group. Based on the randomized allocation sequence, either lidocaine patches or placebo patches will be attached near each participant’s surgical wound after open hernia repair under general anesthesia. Participants will be asked to follow up at our outpatient clinic on the first postoperative day and at 1 week after surgery. The primary outcome is pain intensity, which will be measured using the visual analog scale (VAS) at the time of discharge from the day surgery unit. The secondary outcomes are VAS score at 24 h and 1 week after surgery. We will collect and analyze the participants’ clinical data (amount of intraoperative opioid use, time to recovery, and pain intensity at 30 min after surgery) and demographic characteristics (age, sex, body weight, and height). DISCUSSION: This trial may not only provide evidence on the efficacy of a 5% lidocaine patch for acute postoperative pain management after unilateral inguinal hernia repair, but also demonstrate the efficacy and safety of the patch for post-discharge pain management. TRIAL REGISTRATION: ClinicalTrials.gov NCT04754451. Registered on February 10, 2021. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13063-022-06700-3.