Evaluation of injection volumes for the transversus abdominis plane block in dog cadavers: a preliminary trial

Flavio A V Freitag; Eloisa Muehlbauer; Thalise daS Gaio; Amanda A M Dos Santos; Marcello Machado; Andrea Sanchez; Juan C M Duque

doi:10.1016/j.vaa.2020.10.001

Evaluation of injection volumes for the transversus abdominis plane block in dog cadavers: a preliminary trial

Vet Anaesth Analg. 2021 Jan;48(1):142-146. doi: 10.1016/j.vaa.2020.10.001. Epub 2020 Oct 14.

Authors

Flavio A V Freitag¹, Eloisa Muehlbauer², Thalise daS Gaio², Amanda A M Dos Santos², Marcello Machado³, Andrea Sanchez⁴, Juan C M Duque⁵

Affiliations

¹ Veterinary Sciences Graduate Program, Department of Veterinary Medicine, Federal University of Paraná, Curitiba, PR, Brazil; Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada.
² Veterinary Sciences Graduate Program, Department of Veterinary Medicine, Federal University of Paraná, Curitiba, PR, Brazil.
³ Anatomy Department, Biological Science Sector, Federal University of Paraná, Curitiba, PR, Brazil.
⁴ Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada.
⁵ Veterinary Sciences Graduate Program, Department of Veterinary Medicine, Federal University of Paraná, Curitiba, PR, Brazil. Electronic address: anestesiologiavet@yahoo.com.br.

PMID: 33257280
DOI: 10.1016/j.vaa.2020.10.001

Abstract

Objective: To evaluate staining of nerve branches after the injection of different volumes during ultrasound-guided transversus abdominis plane (TAP) block in dog cadavers.

Study design: Prospective randomized study.

Animals: A total of 15 frozen/thawed adult dog cadavers.

Methods: Hemiabdomens were randomly allocated to one of four groups. In groups G0.3, G0.6 and G1.0, ropivacaine-methylene blue solution (0.3, 0.6 and 1.0 mL kg^-1 in seven, eight and eight hemiabdomens, respectively) was injected at the midpoint between the iliac crest and the last rib at the height of the shoulder. In group G0.3×2 (seven hemiabdomens), two injections (0.3 mL kg^-1) were performed, caudal to the last rib and cranial to the iliac crest at the same height. Total time for injection was recorded; after 30 minutes, cadavers were dissected and spread of dye was evaluated.

Results: Accuracy of injection site was 80% and injection time was 71 (48-120) seconds for all groups together. Craniocaudal spread was 6.4 ± 1.6, 9.1 ± 2.6, 11.4 ± 2.3 and 11.2 ± 3.8 cm for G0.3, G0.6, G1.0 and G0.3×2, respectively [G0.3 to G0.3×2 (p = 0.044) and G1.0 (p = 0.034)]. There was no difference in dorsoventral spread among groups. Number of ventral nerve branches stained was 3 (2-4), 3 (2-4), 3 (3-4) and 3 (2-4) for G0.3, G0.6, G1.0 and G0.3×2, respectively, including nerve branches from twelfth thoracic to third lumbar (L3) in different proportions among groups.

Conclusions and clinical relevance: Results suggest that a single-injection TAP block, using 0.3 mL kg^-1, stains comparable number of nerve branches as higher volumes or two-point injection. Despite the volume or technique, consistent staining of the innervation of the caudal abdomen (L1-L3) was observed. Additional cadaveric studies are necessary to identify the optimal technique for complete abdominal wall staining.

Keywords: TAP block; abdomen; analgesia; local anesthesia; ultrasound.

MeSH terms

Abdominal Muscles
Animals
Cadaver
Dog Diseases*
Dogs
Nerve Block* / veterinary
Prospective Studies
Ropivacaine
Ultrasonography, Interventional / veterinary

Substances

Ropivacaine