Ultrasound guided nerve block anesthesia in animals
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Date
2021-10-14
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Palampur
Abstract
The aim of the study was to recognize the normal ultrasonographic appearance of the brachial
plexus, sciatic and femoral nerves and perform the ultrasound-guided blockade of these nerves
under monitoring by the electrical nerve stimulator. Sixteen calves/cattle and twenty canine
patients presented for the various minor and major surgical procedure were selected for the
study. Lignocaine 2% was used as an anesthetic agent and was infiltrated around the nerve of
interest with the help of the echogenic needle. The spread of the local anesthetic was visualized
in real time with the help of USG guidance. An electrical nerve stimulator was employed for the
confirmation of the accurate needle position in relation to the nerve. Ultrasonographically, the
brachial plexus of dogs and cattle appeared as a hyperechoic entity containing multiple
hypoechoic structures of nerve trunks exiting from the plexus. The brachial plexus was easily
identified and the axillary artery and vein served as useful landmarks for its identification. The
blockade of the plexus provided analgesia distal to the elbow joint in all the patients. The sciatic
nerve block was performed in conjunction with the femoral nerve block. Ultrasonographically,
the sciatic and femoral nerve had a central hypoechoic to anechoic lumen surrounded by the
hyperechoic connective tissue. Ultrasonographic identification of the femoral nerve was difficult
in both cattle and dogs as the nerve does not lend readily to ultrasound visualization, primarily
because of depth or connective tissue interference with ultrasound transmission. Ultrasoundguided nerve block anesthesia of the sciatic and femoral nerve helped in performing surgeries
distal to the stifle joint, thus circumvent the need for any additional anesthesia.The effective
application of ultrasonography reveals two-dimensional anatomy, optimal imaging of the nerves
and anatomical structures, accurate real-time needle guidance, and precise local anesthetic
delivery ensuring successful nerve block with improved patient safety. Use of a nerve stimulator
during ultrasound-guided nerve block yields clinically relevant safety information pertaining to
proximity of the nerve, optimal delivery and minimization of volume of local anesthetic to
produce the nerve blocks. The inplane technique of needle insertion, hydrolocation and
hydrodissection facilitated the identification of d