The association of Serratus Anterior Plane blocks with postoperative opioid use and analgesia following simple lumpectomy: a retrospective cohort analysis

Background The potential benefit of regional interventions for simple lumpectomy breast cancer surgeries has not been well investigated. Understanding which patients to not offer a regional intervention to can be just as important as knowing which would benefit. It is unclear whether fascial plane blocks, such as serratus anterior plane (SAP) block, should be routinely performed for less extensive breast surgeries. Therefore, our goal in this retrospective cohort study was to evaluate the association of integrating SAP blocks into a standard perioperative multimodal analgesia plan in patients undergoing simple lumpectomies (without node biopsies) with perioperative opioid consumption. As secondary outcomes, we also analyzed postoperative pain scores and post-anesthesia care unit (PACU) length of stay. Methods This was a single institution retrospective cohort study (surgical site infiltration only versus SAP block cohorts) assessing the association of SAP blocks to our outcomes of interest. In the adjusted analysis, we created matched cohorts using 1:1 (surgical site infiltration only: SAP block) propensity-score matching using nearest neighbor-matching without replacement. To compare the primary and secondary outcomes in the matched cohorts, we used the Wilcoxon signed rank test. A P-value of < 0.05 was considered statistically significant. Results There were 419 patients included in the analysis, in which 116 (27.7%) received a SAP block preoperatively in addition to our standard perioperative analgesia plan. In an unadjusted analysis, no differences were seen in perioperative opioid consumption, PACU pain scores, and PACU length of stay. Among the matched cohorts, the median [quartile] perioperative opioid consumption in the surgical site infiltration only versus SAP block cohorts were 10 mg [10, 13.25 mg] and 10 mg [7, 15 mg], respectively (P = 0.16). No differences were seen in the other outcomes. Conclusions In this study, we evaluated the impact of SAP blocks on patients undergoing simple lumpectomies, which are relatively less involved breast surgeries. We concluded that routine use of preoperative regional anesthesia is not beneficial for these specific patients. Future studies should focus on identifying patients that would directly benefit from regional interventions.