///2017 Abstract Details
2017 Abstract Details2019-08-02T15:54:53-06:00

The Effectiveness of Transversus Abdominis Plane Blocks for Post-Cesarean Delivery Analgesia in Women on Methadone or Buprenorphine Maintenance During Pregnancy: A Multi-center, Retrospective Cohort Study

Abstract Number: SAT-31
Abstract Type: Original Research

Chaim I Nelson MD 1 ; Marnie B. Welch MD2; Lisa Rae Leffert MD3; Michaela Kristina Farber MD MS4

Introduction

Opioid abuse or dependence in pregnancy increased by 127% from 1998-2011 (1). Women on maintenance opioid therapy have a higher risk of cesarean delivery (CD) and increased postoperative pain requirements (2). Although post-CD analgesia with transversus abdominis plane (TAP) blockade offers little benefit compared to intrathecal morphine for patients in the general obstetric population (3), it is unclear whether TAP blockade may have greater benefit in select high-risk populations. Our hypothesis was that the addition of a TAP block to our multimodal pain regimen would confer superior post-CD analgesia in patients on methadone or buprenorphine maintenance opioid therapy during pregnancy.

Materials and Methods

After IRB approval, we reviewed the anesthesia records of women on buprenorphine or methadone maintenance during pregnancy who underwent CD with Pfannenstiel incision under spinal anesthesia at two academic institutions from January 2011 through January 2017. Exclusion criteria included women with uterine incision other than Pfannenstiel, general or epidural anesthesia without intrathecal opioid dosing, and significant perioperative morbidity. Our primary outcome was analgesia, defined as highest reported visual analog scale (VAS) for pain in the first and second 24 hours after surgery. Secondary outcomes were post-CD intravenous or oral opioid requirement and exposure to non-opioid analgesics. Wilcoxon rank sum and Fisher’s exact tests were performed.

Results

We identified 114 patients, of which 55 met our inclusion criteria, and 5 received TAP block. Maximum VAS scores at 24 hours were 7.0 + 2.2 vs. 5.6 + 0.9 for non-TAP vs. TAP groups (p = 0.158) and maximum VAS scores at 48 hours were 6.3 + 1.9 vs. 8.2 + 1.6 for non-TAP vs. TAP groups (p = 0.0765). There was no difference in opioid requirement between the two groups. Use of multimodal pain regimens involving > 2 non-opioid analgesic adjuncts was standard in both TAP and non-TAP groups, with no difference in exposure.

Conclusion

Our study suggests no difference in 24- and 48-hour maximum VAS scores when a TAP block is added to a multimodal regimen for women on methadone or buprenorphine maintenance in pregnancy, after CD with intrathecal opioid. We demonstrate that despite extensive multimodal analgesic exposure, VAS scores are quite high in this patient population. Given the challenge in managing patients postoperatively who have substantial baseline opioid requirement, the importance of multimodal analgesia cannot be overstated. Analysis of additional patients in this study over time may further elucidate the role for TAP blockade, whether it benefits patients who do not receive intrathecal opioid or exposure to other analgesics, and temporal trends that may reinforce the need for catheter-based analgesics (TAP catheters or epidural infusion). Further studies are warranted.

1. Maeda A et al. 2014

2. Meyer M et al. 2010

2. Loane H et al. 2012

SOAP 2017