Open Approach to the Transversus Abdominis Plane in Horses: A Cadaver Feasibility Study
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Department of Clinical Studies—New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, PA 19348, USA
2
Department of Clinical Science and Advanced Medicine—Matthew J. Ryan Hospital, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
*
Author to whom correspondence should be addressed.
Vet. Sci. 2024, 11(1), 51; https://doi.org/10.3390/vetsci11010051
Submission received: 2 December 2023
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Revised: 19 January 2024
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Accepted: 20 January 2024
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Published: 22 January 2024
(This article belongs to the Special Issue Anesthesia and Pain Management in Veterinary Surgery)
Simple Summary
Peri-incisional infiltration of local anesthetic as well as ultrasound-guided nerve blocks prior to the beginning of abdominal surgery have shown to decrease both intra-and postoperative nociception in our patients, but they can be time- and cost-intensive. A more simplified technique to desensitize the body wall during surgery was investigated in this cadaver study. In this study, the number of attempts to perform the local block as well as the success rate and spread of a dye simulating the local anesthetic were evaluated. We were able to show that it had a satisfactory success rate and was easy and quick to perform. This is the first description of this new and simplified transversus abdominis plane block in horse cadavers. Additional clinical cases will have to be investigated to determine if there is an effect on recovery from anesthesia and postoperative pain.
Abstract
The study’s objective was to evaluate the feasibility and dispersion of an open approach to the transversus abdominis plane (TAP) block in eight adult equine cadavers. A ventral midline incision was made, starting 2 cm cranial to the umbilicus and extending 25 cm cranially. In total, 0.5 mL/kg of new methylene blue (NMB) was injected per horse, divided into six injections. Using an 18 g, 8 cm Tuohy needle, three injections were made per side. The needle was guided blindly into the TAP using palpation. A 60 mL syringe was attached directly to the needle, depositing ~0.08 mL/kg at each site. The time to complete the injections was recorded for each cadaver. Following injection, the ventral body wall was dissected to determine if the dye was present within the TAP space as well as to measure the extent of the dispersion of the dye, the cranial to caudal extent, and the width of the dye’s spread. Complete deposition of NMB into the TAP (six of six sites) was achieved in 5/8 horses. The median time needed to perform all the injections was 263 s. Increased adiposity (retroperitoneal fat) was associated with unsuccessful injections. This approach to the TAP was easily and quickly performed, though less successful in horses with increased retroperitoneal fat and increased BCS.
