Evaluation of cutaneous sensory block area following a novel approach to transversus abdominis plane block: an observational study.

BACKGROUND

Ultrasound-guided transversus abdominis plane (US-TAP) block is currently used as part of a multimodal analgesic regimen in anterior abdominal wall surgery, but the distribution of cutaneous sensory block area (CSBA) shows significant interindividual variation. We predeveloped a novel US-TAP block approach, and this study aims to assess the CSBA following the novel US-TAP block approach.

METHODS

Sixteen patients undergoing elective laparoscopic cholecystectomy (LC) received bilateral novel US-TAP blocks with a total of 40 mL of 2.5 mg/mL ropivacaine. Measurements were taken 45 min after block administration. CSBA was mapped using cold sensation and a sterile marker, photodocumented, and transferred to a transparency. The area of the CSBA was calculated from the transparencies.

RESULTS

The median CSBA of the novel US-TAP approach was 332 cm2 (IQR 297-413 cm2; range 258-466 cm2). In all patients, the CSBA showed wide periumbilical distribution. In all 32 unilateral blocks (100%), both epigastric and infraumbilical components were present; and in 16 of the 32 blocks (50%), the CSBA extended to the abdominal wall lateral to the vertical reference line through the anterior superior iliac spine. Fourteen patients (88%) had resting NRS scores of 3 or lower within 24 h postoperatively.

CONCLUSION

The novel US-TAP approach produces a broad dermatomal CSBA, covering much of the abdominal wall around the umbilicus.

CLINICAL TRIAL REGISTRATION: https://www.chictr.org.cn/showproj.html?proj=211485, ChiCTR2300077899.