Presented at the 2012 AAPM Annual Meeting « Back

The Spread of Contrast Following an Ultrasound-Guided TAP Injection: A Cadaver Study

Dustin M. Cole, MD, cole.dustin@mayo.edu¹, Halena Gazelka, MD¹, Susan M. Moeschler, MD¹, (1) Mayo Clinic, Rochester, Minnesota

Introduction: The transversus abdominis plane (TAP) block is frequently used in perioperative settings [1-3]. It also has diagnostic and therapeutic potential for patients with chronic abdominal wall pain. TAP blocks have traditionally been performed with a blind “double-pop” technique, relying on tactile sensation with variable accuracy [4]. With ultrasound guidance, the transversus abdominis (fascial) plane (TAP) between the internal oblique and transversus abdominis muscles is easily identified. The TAP contains the thoracolumbar nerves, which provide sensory innervation to the abdominal wall [5,6]. Purpose: The purpose of this study was to 1) help quantify the optimal volume of medication required with TAP blockade to adequately cover the thoracolumbar nerves, and 2) describe injectate spread with 3-D image reconstruction following ultrasound-guided TAP injection. Methods: Following institutional approval, two fresh frozen cadaver torsos were obtained. One TAP block was performed per side on each cadaver torso with predetermined contrast volumes of 5, 10, 15, or 20 cc. Ultrasound was used to identify the TAP layer in the midaxillary line, and to perform the injection (Figure 1). 3-D radiographic reconstruction of the anatomy and contrast spread pattern was then performed. Images were interpreted by a radiologist to define volumetrics and area of spread. Discussion: Ultrasound-guided TAP blockade may be an effective treatment alternative to trigger-point injections for chronic abdominal wall pain. More research is needed to determine its role in this pain population. This study helps further the understanding of injectate spread following ultrasound-guided TAP injections. References: 1)Bonnet, F., J. Berger, and C. Aveline, Transversus abdominis plane block: what is its role in postoperative analgesia? Br J Anaesth, 2009. 103(4): p. 468-70. 2)Carney, J., et al., The transversus abdominis plane block provides effective postoperative analgesia in patients undergoing total abdominal hysterectomy. Anesth Analg, 2008. 107(6): p. 2056-60. 3)El-Dawlatly, A.A., et al., Ultrasound-guided transversus abdominis plane block: description of a new technique and comparison with conventional systemic analgesia during laparoscopic cholecystectomy. Br J Anaesth, 2009. 102(6): p. 763-7. 4)Reid, S.A., The transversus abdominis plane block. Anesth Analg, 2007. 105(1): p. 282; author reply 282-3. 5)Hebbard, P., et al., Ultrasound-guided transversus abdominis plane (TAP) block. Anaesth Intensive Care, 2007. 35(4): p. 616-7. 6)Hebbard, P.D., M.J. Barrington, and C. Vasey, Ultrasound-guided continuous oblique subcostal transversus abdominis plane blockade: description of anatomy and clinical technique. Reg Anesth Pain Med, 2010. 35(5): p. 436-41.

Funding: None.