Exploring the sensory coverage of subcostal ultrasound-guided TAP blocks

The transversus abdominis plane (TAP) block, crucial for managing postoperative pain, varies in effectiveness depending on the approach used. The 2024 study by Salmonsen et al. aimed to assess the cutaneous sensory block area (CSBA) following a subcostal ultrasound-guided TAP (US-TAP) approach.

Thirty patients undergoing elective laparoscopic cholecystectomy received bilateral subcostal US-TAP blocks with 20 mL of 2.5 mg/mL ropivacaine.

The median CSBA was 174 cm², showing significant variability, and was primarily distributed around the periumbilical area. In 70% of cases, the CSBA extended both epigastrically and infraumbilically, while 20% covered only the epigastrium and 7% only the infraumbilical region (Fig-1). None extended laterally beyond a vertical line through the anterior superior iliac spine.

Fig-1. A visual presentation of the cutaneous sensory block area (CSBA) after bilateral subcostal ultrasound-guided transversus abdominis plane block.

The subcostal US-TAP results in a heterogeneous non-dermatomal CSBA with varying size and distribution across the medial abdominal wall, which differs from the posterior US-TAP approach. The subcostal TAP primarily covers the medial abdominal wall, making it particularly suited for gastrointestinal and gynecological surgeries where incisions are centrally located. Compared to the posterior TAP, which covers a larger area with a median CSBA of 321 cm², the subcostal TAP is more targeted, covering only the medial abdominal region and thus providing effective medial abdominal coverage.

This study highlights the importance of understanding the sensory distribution of different TAP approaches, thereby underscoring the potential benefits of the subcostal US-TAP block in surgeries with medial abdominal incisions.

To read the full paper in RAPM, copy-paste this into your Google search: 

Salmonsen CB, Lange KHW, Rothe C, et al. Cutaneous sensory block area of the ultrasound-guided subcostal transversus abdominis plane block: an observational study. Reg Anesth Pain Med. 2024;49:289-292.

https://rapm.bmj.com/content/49/4/289

Learn more about the different approaches to the TAP block—lateral, anterior, and posterior—by enrolling in the Regional Anesthesia Manual e-Course (formerly Compendium). Access this valuable resource today on the NYSORA website!