Uso da anestesia locorregional periférica em caninos e bovinos: um estudo clínico e experimental

Abstract

The aim of this thesis was to conduct a thorough study of local regional anesthesia techniques by using a peripheral nerve locator in bovine and canine. In addition, the efficacy of this procedure with the volume of anesthetics applied was evaluated by using nociceptive electrical and mechanical techniques, as well as physiological parameters. Four experiments were carried out at the Veterinary School of the Universidade Federal de Minas Gerais. Local regional anesthesia can serve as a substitute for general anesthesia in bovine or as a complement of general anesthesia in dogs. The use of a peripheral nerve locator allows real time monitoring of the nerve to be blocked. In the present study, blocking of brachial plexus, radial, median, musculocutaneous, ulnar, sciatic, femoral, tibial and lumbar nerves were performed at five moments (basal evaluation up to 60 minutes after blockage). Experiment 1 consisted in the study of the anatomy of the peripheral nerves of canine and bovine through dissection of embalmed specimes at the Laboratório de Anatomia Animal do ICB da UFMG. The nerves included: brachial plexus, sciatic, tibial, femoral and some bovine costoabdominal nerves. In experiment 2, local regional anesthesia was evaluated in canine with a peripheral nerve locator. Lidocaine and bupivacaine were used. No significant differences (P>0,05) were seen between the drugs and any of the moments, as well as for any of the factors in the mechanical and electrical pain model. Experiment 3 was the same as that described for experiment 2, using bovine instead of canine. Cardiac and respiratory frequencies, as well as the responses under a proposed pain model (mechanical and electrical) were measured. The results of the animals that were blocked with bupivacaine were similar (P>0,05) regardless of the use of the blocking or the moment. The animal groups given lidocaine for blocking sciatic and tibial nerves at moments 3 and 4 (M3 and M4) showed similar results (P>0,05); however, these values were inferior (P<0,05) when compared to all the other groups. The evaluations of the proposed pain model demonstrated the efficacy of the nerve blocking in the thoracic limb, regardless of the drug, as well as the efficacy of the dose reduction of bupivacaine. In experiment 4, different volumes of lidocaine (5 mL e 10 mL) were compared in local regional nerve blocking of the bovine pelvic limb (sciatic and tibial nerves). There was a significant effect between the lidocaine doses and the variables of respiratory frequency and the response in the electrical and mechanical pain model.