Can Post-operative TAP Block Improve Quality of Recovery After C-sections in Patients on Methadone Maintenance?

Introduction: Cesarean sections are the most common surgical operations performed in the U.S (1). Patients requiring c-section who are on methadone maintenance often have uncontrolled pain due to opioid tolerance. The current treatment is to utilize large amounts of opioids via PCA thus resulting in a challenging situation with poor patient satisfaction. The Transversus abdominis plane (TAP) block has been studied with success in many abdominal surgeries including c-sections (2-5). The anterior abdominal wall is innervated by anterior divisions of spinal segmental nerves which lie between the transversus abdominis and internal oblique muscle layers. Blockade of these nerves with local anesthetics may last up to 24 hours. There have been no efficacy studies performed using the TAP block in patients receiving chronic methadone maintenance undergoing c-sections. Methods: This is a prospective randomized double-blind placebo controlled study (0.375% Ropivacaine vs. 0.9% saline) designed to evaluate the effectiveness of transverse abdominis plane (TAP) block in the first 48 hours after c-section in patients receiving methadone therapy. The TAP block will be performed by a regional anesthesiologist in the operating room after delivery of the baby. Objective: The primary objective of this study is to measure pain levels after c-sections in patients receiving methadone therapy utilizing visual analog scale (VAS) and assessing opioid consumption during the first 48 hours compared to placebo. Conclusion: It is hypothesized that patients receiving TAP block will have decreased pain intensity and less opioid consumption during the first two postoperative days compared to placebo. Therefore we believe postoperative TAP block to be an effective adjuvant to pain control for patients on methadone maintenance following c-section.