Cutaneous sensory block area of the laparoscopic-assisted transversus abdominis plane block

INTRODUCTION: Different approaches and techniques are used to apply a transversus abdominis plane block (TAP), but their characteristics are poorly described. Precise injection of local anaesthetic is considered crucial to achieving the desired block effect. Laparoscopic-assisted TAP (L-TAP) is a blind technique and potentially less reliable than ultrasound (US)-guided techniques. This study assessed the cutaneous sensory block area (CSBA) after an L-TAP adopting a subcostal dual block approach.

METHODS: Thirty elective laparoscopic cholecystectomy patients received bilateral L-TAPs. The CSBA was mapped 150 min. after block application using cold sensation and a sterile marker, photo-documented and transferred to a transparency sheet from which the area was calculated.

RESULTS: The median CSBA of the subcostal bilateral dual L-TAP was 161 cm2 (interquartile range: 131-217 cm2; range: 67-408 cm2). In all patients, the CSBA mainly covered the skin over the epigastrium, whereas 23% also had an infraumbilical component. In none of the patients did the CSBA cover the abdominal wall laterally to a vertical line through the anterior superior iliac spine.

CONCLUSION: The subcostal bilateral dual L-TAP produces a heterogeneous non-dermatomal CSBA of varying size and distribution across the medial epigastric abdominal wall, similar to the CSBA described in the existing literature on US-guided subcostal TAP.

FUNDING: The authors have no sources of funding to declare for this manuscript.

TRIAL REGISTRATION: Not relevant.