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.

Inclusion Criteria:

- Laboring patients will only be enrolled in the study if they have a c-section
performed. Inclusion criteria include patients who are 18-40 yr of age, ASA physical
status I-III, 50-100 kg, 150 cm tall or greater, and English-speaking

Exclusion Criteria:

- Patient refusal, methadone use for chronic pain, contraindications to administration
of regional anesthesia (e.g., allergy to a local anesthetic, local infection and
coagulopathy), significant neurologic disorders of the lower extremity, and
psychiatric or cognitive disorders.