Veterinary Medicine - March 2009 - (Page 137)

blocks, may be improved with the use of a nerve locator, which helps to accurately locate the peripheral nerves.14-16 The nerve locator consists of a constant current generator, a grounding patient electrode, an electrode attached to an insulated stimulating needle, and an extension set attached to a syringe for injection of local anesthetic (see boxed text “Nerve location through electrical nerve stimulation”). The use of nerve stimulators to locate peripheral nerves is routine in human surgical procedures, and the body of literature is extensive. Several meta-analyses of the human literature indicate that peripheral nerve blockade supplies equivalent postoperative analgesia and an improved side effect pro le compared with epidural analgesia.17,18 A recent study in dogs demonstrated the ef cacy of a nerve stimulation-guided blockade of the brachial plexus for analgesia distal to the shoulder.16 Another report described the successful use of a nerve stimulator to perform a brachial plexus block for carpal arthrodesis in a dog.19 Subsequently, the use of a nerve stimulator to identify the brachial plexus of 20 dogs undergoing distal thoracic limb procedures was described.20 Ten dogs received a mixture of lidocaine and bupivacaine, and 10 dogs received an equal volume of saline solution. Intraoperative and postoperative opioid requirements were signi cantly lower in dogs that received the local anesthetics. The use of a nerve stimulator to assist in the placement of an indwelling perineural catheter near the brachial plexus of a dog with severe trauma of the distal thoracic limb has also been reported.15 A recent abstract compared the use of a nerve locator to achieve lumbar plexus blockade with bupivacaine vs. systemic administration of methadone to dogs undergoing hindlimb orthopedic procedures.21 Intraoperative iso urane requirements were lower in the locoregional group, and cardiovascular parameters were improved.21 The use of a nerve locator to facilitate mandibular nerve blocks in crocodilians has been described.22 A recent study described dissection of the brachial plexus, sciatic and femoral nerves, identi cation of relevant anatomical landmarks, and the use of a nerve stimulator to locate these nerves in four anesthetized dogs.14 Disappointingly, the use of a nerve locator did not result in increased staining of the brachial plexus with new methylene blue when compared with a blind technique in one study.23 The volumes of local anesthetic for use in brachial plexus, lumbar plexus, and sciatic nerve blocks, based on distribution of an injected lidocaine and methylene blue solution, have been investigated.24 Local anesthetic volumes of 0.3 ml/kg were found to adequately stain the nerves of the brachial plexus, whereas 0.05 ml/kg was judged appropriate for sciatic nerve block. The lumbar plexus appeared to require a volume of 0.4 ml/kg, but statistical signi cance was not reached. VETERINARY MEDICINE March 2009 137 http://www.thecvc.com

Table of Contents Feed for the Digital Edition of Veterinary Medicine - March 2009

Veterinary Medicine - March 2009 Contents Letters Correction Author Guidelines Hot Literature Idea Exchange A Challenging Case Local and Regional Anesthesia Techniques The Latest Scoop on Litter Product Preview CE Form/Advertiser Index Marketplace/Classifieds Mind Over Miller

Veterinary Medicine - March 2009

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