Cutaneous sensory block area of the ultrasound-guided subcostal transversus abdominis plane block: an observational study.

BACKGROUND AND OBJECTIVES: The transversus abdominis plane block (TAP) can be applied using different approaches, resulting in varying cutaneous analgesic distributions. This study aimed to assess the cutaneous sensory block area (CSBA) after ultrasound-guided TAP (US-TAP) using the subcostal approach. METHODS: Thirty patients undergoing elective laparoscopic cholecystectomy received a subcostal US-TAP with 20 mL 2.5 mg/mL ropivacaine bilaterally. Measurements were performed 150 min after block application. The 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 subcostal US-TAP was 174 cm2 (IQR 119-219 cm2; range 52-398 cm2). In all patients, the CSBA had a periumbilical distribution. In 42 of the 60 (70%) unilateral blocks, the CSBA had both an epigastric and infraumbilical component; in 12 of the 60 (20%) unilateral blocks, it covered only the epigastrium; and in 4 of the 60 (7%) unilateral blocks, it had only an infraumbilical distribution. No CSBA was found in 2 of the 60 (3%) unilateral blocks. In none of the patients did the CSBA cover the abdominal wall lateral to a vertical line through the anterior superior iliac spine. CONCLUSION: The subcostal US-TAP results in a heterogeneous non-dermatomal CSBA with varying size and distribution across the medial abdominal wall.

Optimal peripheral nerve block after minimally invasive colon surgery - a study protocol for a randomised trial.

Introduction Transversus abdominis plane (TAP) blocks are used for post-operative pain management, but their efficacy remains unclear. We aim to investigate the effect of two TAP block methods in minimally invasive colon surgery. Methods This will be a double-blind, randomised and controlled multicentre trial including 360 adults who are planned for elective minimally invasive colon surgery with curative intent for colon neoplasia. The participants are randomised to one of three arms: active ultrasound-guided TAP (US-TAP) and placebo laparoscopic assisted TAP (L-TAP), placebo US-TAP and active L-TAP, or placebo US-TAP and placebo L-TAP. The primary outcome is morphine dose equivalents administered during the first 24 hours after surgery. Secondary outcomes are pain on the first post-operative day, length of stay, post-operative nausea and vomiting, and quality of recovery measured using the Quality of Recovery 15 questionnaire. Statistical analysis will determine any superiority of US-TAP and L-TAP versus placebo, and any non-inferiority of L-TAP compared with US-TAP. The latter will only be tested if superiority to placebo is shown. Primary and secondary outcomes will be analysed as intention-to-treat regarding superiority and as intention-to-treat and per protocol regarding non-inferiority. Conclusion This will be the first ever blinded multicentre trial comparing L-TAP, US-TAP and placebo in daily clinical practice. The study has the potential to determine the role of the TAP in minimally invasive colon surgery. Funding A and JC Tvergaards Fond, Helen Rudes Fond, Fru Olga Bryde Nielsens Fond, Aage og Johanne Louis-Hansen Fond, Medicine and Treatment Research Fund of the Danish Regions and a Research Grant from Copenhagen University Hospital - North Zealand Hospital. Trial registration ClinicalTrials.gov: NCT04311099.