Abstract
OBJECTIVES: To examine the feasibility and potential efficacy of 5% lidocaine medicated plaster for acute postoperative pain in a parallel, blinded, randomized controlled pilot trial. METHODS: Twenty-eight women undergoing elective gynecological surgery with midline incisions were randomly allocated 5% lidocaine medicated patch (Lignopad) or placebo plasters. Postoperative pain at rest and on movement at 24 hours were the primary study endpoints, with secondary endpoints of postoperative pain within the first 48 hours, cumulative morphine consumption (mg), predicted peak flow rate (PFR) (%) and adverse effects. We assessed pain scores at rest and on movement using the visual analogue scale (0-100). RESULTS: The lidocaine patch group had lower postoperative pain scores at rest at 24 hours (mean difference [MD] -15.1, 95% confidence interval [95% CI] -28.3 to -2.0; P = .024) but not on movement at 24 hours (MD -6.4, 95% CI -22.7 to 9.9; P = .445). Compared to placebo, lidocaine may slightly lower cumulative morphine consumption (mg) over time (MD -3.4, 95% CI -6.9 to 0.2; group*time interaction P = .065). The difference in improvement in the PFR over time after surgery between groups appeared small (group*time P = .0980). No adverse effects occurred. CONCLUSIONS: Lidocaine patch may provide a clinically important reduction in postoperative pain intensity. A larger trial to confirm the efficacy and safety of lidocaine patch is feasible after modifying the inclusion criteria and collecting patient-centered outcomes, such as quality of recovery and patient satisfaction.