Bloqueio do plano transverso do abdome guiado por ultrassom em Medicina Veterinária: revisão de literatura e avaliação anatômica em felinos domésticos.

Abstract

The evolution of Veterinary Medicine, there was a considerable increase in the number of surgical procedures, and for its accomplishment, it is important that safe and effective anesthetic methods are used. Locoregional blocks are anesthetic techniques that provide effective analgesia for a wide variety of surgical procedures, reducing the consumption of hypnotic drugs and analgesics. The abdominal wall is one of the main structures that suffer from acute postoperative pain in abdominal cavity surgeries and can be prevented with the use of locoregional blocks. Transversus abdominis plane block (TAP) or "TAP Block" is a regional anesthesia technique where the deposition of local anesthetics in the fascial plane between the transverse abdominal and internal oblique muscles, aiming to anesthetize afferent branches of the caudal and lumbar cranial nerves that innervate the abdominal wall. The objective of this study was to review anatomical and clinical works performed with the transversus abdominis plane block technique in veterinary medicine, even as, evaluate the TAP Block technique in domestic felines, using bupivacaine hydrochloride 0.25% and methylene blue, defining a distribution real of the solution by a single point of infiltration, bilaterally, and efficacy of this block for the abdominal surgeries of feline in vivo. Seventeen feline cadavers were used, the TAP Block technique was used with 1: 1 solution bupivacaine hydrochloride 0.25% and methylene blue at volume of 0.75 mL/kg. Ultrasound guided block with 5-10MHz linear probe was performed in a single point, bilaterally. The cadavers were dissected for analysis of the nerve structures and muscle involved with the block. Adequate staining was determined by a minimum of 1 cm of dye along the long axis of the nerve. 34 hemiabdominal walls of feline cadavers were visualized by ultrasound, each hemiabdome was infiltrated and classified individually. In 58.82% of the infiltrated sides, the dye was correctly distributed in the transverse abdominal fascial plane, the more cranial diffusion of the solution reached the T13 nerve in 15% of the cases, and the more caudal blistered the L3 nerve, representing 35% of cases. The L1 and L2 nerves were most commonly involved in the dispersion of the solution, with 85% and 95% frequency, respectively. In the other infiltrations the dye solution did not reach the desired plane, with 11.77% being infiltrated in the peritoneum and 29.41% in the plane between the external and internal oblique muscles. Under the conditions used in this experiment, the success rate of the bilateral TAP Block in the same cadaver was 41.18%. The technique employed proved to be difficult to perform in domestic felines, especially with the medium resolution transducer employed. In addition, the dispersion obtained characterized possible ineffective anesthetic blockades for abdominal surgeries. Future studies should evaluate different volumes and concentrations, and toxicity risks for the feline species, seeking to standardize the TAP Block technique.