Injectable lidocaine provides similar analgesia compared to transdermal lidocaine/tetracaine patch for the incision and drainage of skin abscesses: a randomized, controlled trial.

Background: Local anesthesia used for incision and drainage of abscesses is known to be painful.

Study Objective: We studied the analgesia provided by a lidocaine/tetracaine patch compared to injectable lidocaine during incision and drainage (I&D) of skin abscesses.

Methods: This was a prospective, double-blind, randomized, controlled trial carried out in the Emergency Department (ED) of an adult tertiary referral center. Adult patients with a skin abscess in need of I&D were randomized to one of two groups. One group received a lidocaine/tetracaine patch and injectable normal saline for anesthesia. The second group received a placebo patch and injectable 1% lidocaine. A visual analog pain scale was used to record the patient's pain level prior to treatment, during the procedure, and after I&D.

Results: There were 20 patients enrolled in the study, including 12 randomized to the lidocaine/tetracaine patch and 8 to the injectable lidocaine. Pain scores preprocedure were similar in the two groups. Pain scores during I&D and postprocedure were compared between groups using a paired t-test. Patients receiving injectable lidocaine experienced pain that was similar (50.1 ± 5.9 mm; 95% confidence interval [CI] 45.2-55.1) to those receiving the transdermal lidocaine/tetracaine patch (60.1 mm ± 11.0; 95% CI = 55.2-68.1), p = 0.04, with a power of 80% to detect a difference of 20 mm at p ≤ 0.05; although this was statistically significant, it was not clinically significant. There was also no statistical difference between the two groups in the postprocedure pain scores (p = 0.65).

Conclusion: Local injection of lidocaine provided clinically similar analgesia compared to the lidocaine/tetracaine patch during I&D of skin abscesses in the ED. Pain at presentation and after the procedure was similar in both groups. Emergency physicians should continue to use a local injected anesthetic for I&D of skin abscesses until a less painful alternative is identified.