SP34. Abdominal Peripheral Nerve Blocks Do Not Impact Post-operative Pain in Free Flap Breast Reconstruction: A Call to Revisit Eras Protocols

PURPOSE: Transverse abdominis plane (TAP) and rectus sheath (RS) blocks are utilized in enhanced recovery after surgery (ERAS) protocols, but with highly variable methodologies and outcomes in reported literature. The purpose of this study was to evaluate the efficacy of nerve blocks in free flap breast reconstruction as they pertain to post-operative pain. METHODS: Retrospective review was conducted on patients undergoing breast reconstruction with deep inferior epigastric artery perforator (DIEP) free flaps at a large academic institution. Patients who underwent non-DIEP flap breast reconstruction (e.g., thigh-based flaps), who required additional procedures in the immediate perioperative period (e.g., urgent re-operation for flap compromise, chest tube for post-operative pneumothorax), and who were placed on a PCA were excluded from analysis. Target variables included history of chronic pain diagnosis, laterality of reconstruction, timing of reconstruction (immediate vs delayed) and nerve block type (TAP or RS). Outcomes included daily and total opioid oral morphine milligram equivalents on post-operative days one to three. Patient cohorts were analyzed by TAP block, RS block, or no block. Blocks were performed by surgeons intra-operatively. Standard statistical analysis was performed with Chi-Square tests and t-tests, with significance set to p < 0.05. RESULTS: Between January 2021 and December 2023, 225 patients were available for analysis; 87 received TAP blocks, 72 received RS blocks, and 66 received no block. Demographics by peripheral nerve block group are available in. Patient and surgical characteristics and association with postoperative pain medication requirements are available. Patients with chronic pain diagnoses and who underwent bilateral reconstruction had higher total post-operative opioid requirements. Overall post-operative outcomes by peripheral nerve block group are available. There were no significant differences in hospital length of stay or post-operative pain medication requirements between the three groups before or after controlling for multiple co-variables. CONCLUSION: In this large cohort of abdominal-based free flap breast reconstruction patients, there was no impact of peripheral nerve block or nerve block type on post-operative pain medication requirements or hospital length of stay. Our data suggests that ERAS protocols have decreased post-operative pain medication requirements, but this is unlikely attributed to peripheral nerve blocks. Our data suggests continuing routine implementation of ERAS protocols in free flap breast reconstruction including peri-operative multimodal analgesia, with potential for omitting or revising peripheral nerve block practices.