Bloqueio de plexo braquial guiado por neuroestimulador para amputação em bezerro / Nerve stimulator-guided brachial plexus block performed in the amputation of a calf’s forelimb

ABSTRACT

Background: Locoregional anesthesia techniques enable the performance of procedures in the distal portion of the limbs,through the parenteral administration of local anesthetic nerve block. There are devices that can increase the effectivenessof these blocks by accurately locating the nerves. These devices include peripheral nerve stimulators, which enable anesthetic to be injected near the plexus, thus reducing the volume of anesthetic required and allowing for the specific blockadeof a nerve branch by desensitizing exclusively the area of interest. This paper describes the use of nerve stimulator in thebrachial plexus block (BPB) of a calf subjected to amputation of the left foreleg.Case A newborn calf weighing 30 kg, with a history of injury to the left foreleg, was treated at the Veterinary Hospital ofthe Federal Rural University of the Semi-Arid Region. Clinical and X-ray examinations revealed a fracture in the medialportion of the metacarpus and radiographic alterations indicative of osteomyelitis, so amputation of the affected limb wasrecommended. Prior the beginning, during and after the surgical procedure, the animal was submitted to the evaluation ofits physiological parameters (heart and respiratory rate, capillary refill time, diastolic, systolic and mean blood pressure andrectal temperature). Because it is a newborn animal, it was decided not to pre-operatively fast. After applying preanestheticmedication (xylazine 0.01 mg/kg IV), anesthesia was induced with ketamine (2 mg/kg IV) and midazolam (0.3 mg/kg IV)and maintained with isoflurane. For the brachial plexus block, 0.4 mL/kg (1.5 mg/kg) of 0.375% bupivacaine was usedand aided by a peripheral nerve stimulator to generate 10 mA current, 1 HZ frequency and 100 μs pulse duration, coupledto a nerve stimulation needle, it was possible to observe flexion movements...