Bupivacaine for Post-operative Pain in Mohs

Mohs micrographic surgery (MMS) is the first-line treatment for high-risk nonmelanoma skin cancer (NMSC) and is increasingly used for melanoma and other cutaneous neoplasms. The surgical technique involves multiple stages of surgery followed by reconstruction and is typically performed under local anesthesia in the office setting in one day.

MMS is generally well tolerated, but post-operative pain is common. Pain peaks on the day of surgery and slowly declines in subsequent days. Risk factors for increased pain may include flap or graft repair type, location on scalp, lip, nose, or ear, younger age, and increased number of lesions treated. Post-operative pain medication is not standardized in dermatological surgery, but often includes non-narcotic analgesics including acetaminophen and ibuprofen, and less commonly narcotic analgesics such as tramadol and oxycodone. Given the current national trend to reduce opioid use, a multimodal approach to pain management has been adopted by many surgical specialties to optimize analgesia perioperatively.

The most commonly used anesthetic in MMS is local subcutaneous infiltration of lidocaine 0.5 - 2% with 1:100,000 - 1:200,000 epinephrine. Lidocaine is quick-acting, can be buffered to reduce injection pain, and is well tolerated, but the duration of action is only two hours, making it less effective for post-operative pain. Bupivacaine with epinephrine has a longer duration of action compared to lidocaine (up to four hours), but it is rarely used alone due to slower onset of action and more painful injection compared with lidocaine. Bupivacaine is used in many other surgical specialties, including general, plastic, and orthopedic surgery, as a peri-operative adjuvant and has been shown to reduce post-operative opioid use. It is generally well tolerated, carrying a class-effect risk of cardiac toxicity in high doses as does lidocaine, but has been shown to be safe in dermatologic surgery when used for wound infiltration. A newer formulation of liposomal bupivacaine has been shown to be even longer lasting and safer, with pain control up to 72 hours and no reported cardiac toxicity. In addition, a recent study has showed subcutaneous infiltration of bupivacaine with epinephrine to be an effective intra-operative pain adjuvant during MMS compared to lidocaine alone.

Pain control post-operatively in MMS may be optimized by including bupivacaine injections at the end of the surgical procedure given its long-lasting anesthetic effects. There are currently no studies addressing the use of bupivacaine as an adjuvant to control post-operative pain during MMS. The investogators propose a prospective randomized controlled trial to evaluate the effectiveness of bupivacaine injection at the conclusion of surgery for reducing post-operative pain and analgesic use.