Younger women with more pronounced benefit from combination liposomal bupivacaine pudendal block during posterior colporrhaphy

Abstract

To evaluate the effect of age on vaginal pain on patients undergoing posterior colporrhaphy and analyze pain and analgesic use after preoperative regional pudendal nerve block. We hypothesized that pain and analgesic use would be higher in the younger population and that a combination of 1.3% liposomal and 0.25% plain bupivacaine intervention group would have the most benefit in the young. This was a secondary analysis of two double-blinded, randomized controlled trials that included patients undergoing a posterior colporrhaphy, either independently or in conjunction with other vaginal or abdominal reconstructive procedures. Analyzed patients were previously block randomized to a preoperative pudendal block of combined 1.3% liposomal and 0.25% plain bupivacaine versus 0.25% plain bupivacaine alone, (120 patients; Dengler) or postoperative normal saline via transperineal injections (49 patients; Jones). Double-blinding was achieved by covering four 5ml syringes containing the randomized local anesthetic. Both studies were performed at the same institution with multiple fellowship-trained female reconstructive surgeons. Prospective data collected from 2014 to 2020 from 169 patients were analyzed, 60 in the combined liposomal arm, 60 in the non-liposomal arm, and 49 in the normal saline arm. There were no significant differences in demographics, including baseline vaginal pain. Vaginal pain on postoperative day 1 was significantly inversely related to age (p=.002), higher in younger patients. This relationship was significantly influenced by treatment with combined liposomal versus non-liposomal bupivacaine (p=.007) (Figure 1). There was no significant difference found between non-liposomal and the normal saline arm. Combined liposomal bupivacaine resulted in decreased pain in patients below 56.6 years, with the lower bound of a bootstrapped estimate at 45.5 years. By postoperative day 3, the benefit for the combined arm had an overall marginal trend of decreasing pain across age (p=.056) but was not statistically significant. An analysis for outpatient morphine milligram equivalents up to postoperative day 3 in Dengler’s study revealed a similar effect of age (p<.0001) and interaction with combined liposomal versus non-liposomal bupivacaine (p=.02), with a similar age estimate (57.2 years). For patients under age 57, those who received liposomal bupivacaine required less outpatient morphine milligram equivalents than non-liposomal patients (median 22.5 vs 37.5, p=.047) (Figure 2). Women under age 57 who had combined liposomal pudendal block before posterior colporrhaphy had reduced vaginal pain and required less morphine milligram equivalents compared to the non-liposomal bupivacaine block or normal saline perineal injection. Given these findings, the combined pudendal block is most beneficial in a younger patient population.