Interpectoral Nerve Blocks May Lower Postoperative Narcotic Use after Mastectomy.

Background: Pain management following mastectomy is a significant challenge often requiring opioids. Nonopioid pain management utilizing nerve blocks has been shown in other fields to reduce postoperative opioid use and may be effective for postoperative pain in mastectomy patients. The primary purpose of this study was to compare postoperative opioid use, measured in morphine milligram equivalents (MME), between mastectomy patients who underwent interpectoral nerve block (IPNB) and a historical control group. Secondary outcomes included length of stay (LOS) and postoperative pain scores. Methods: This is a single-center, retrospective cohort study. The charts of women who underwent mastectomy for cancer without immediate reconstruction from 10/2017-12/2019 were reviewed. Wilcoxon rank sum test was used for unadjusted analysis and multiple linear regression for adjusted analysis. Results: There were 105 patients included in this study, of which 37 (35%) underwent IPNB. In unadjusted analysis, median MME use was significantly lower in patients that received IPNB compared to the control group (IPNB = 5, controls = 17, p = 0.03). Patients that received IPNB had an observed reduction in LOS and postoperative pain, though these results failed to reach statistical significance. There were no IPNB-related complications. Conclusions: IPNB may be an effective strategy to decrease postoperative opioid use in mastectomy patients. Larger, prospective studies are needed to further investigate the effectiveness of IPNB.