Local anesthesia: regional (intravenous regional analgesia, IVRA, Bier block)
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Requirements
Preparation
Procedure
Aftercare
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Sources
Introduction Many surgical procedures routinely carried out under general anesthesia can be performed under local anesthesia. Uses Useful for foot surgery since torniquet reduces hemorrhage at surgical site. Useful for biopsies, removal of foreign body from paw. Useful for animals with systemic disease which would complicate general anesthesia. Does not distort surgical site. Advantages Simple equipment required. Disadvantages Inadequately restrained animal may move during procedure. Must identify limit of anesthetized area before operating. Alternative techniques IVRA plus neuroleptanalgesia. General anesthesia. Time required Preparation A few minutes to gather equipment. Procedure A few minutes to administer local anesthesia. Decision taking Criteria for choosing test Assess nature of surgery and temperament of patient. Risk assessment Medical condition of patient and risk of anesthesia should be weighed against performing procedure in non-sedated (or unsedated) animals. Materials required Minimum equipment Torniquet. Can use purpose bought tourniquets, stout elastic (rubber) bands, Penrose drains. These can be tied around the limb, or clamped tight with a hemostat. Minimum consumables Needle and syringe. Local anesthetic lidocaine Do not exceed 3 mg/kg total dose of local anesthetic. Ideal consumables Intravenous cannula/catheter. Pre-medication May be required. Neuroleptanalgesia techniques would be ideal. Restraint Additional sedation or in some cases general anesthesia required. Neuroleptanalgesia would be a good choice for this technique. Assistant required to restrain animal. Approach Step 1 -
Place torniquet Position torniquet around proximal limb, proximal to the surgical site. Tourniquet must be tight enough to occlude arteries and veins. Check that no pulse distal to the tourniquet, ie that tourniquet sufficiently tight. Can also use stout elastic bands, or Penrose drains Core Procedure Step 1 -
Place intravenous catheter Insert venous catheter with tip distal to tourniquet Step 2 -
Inject local anesthetic Lidocaine: <5 mg/kg. Bupivicaine: 3 mg/kg. Do not exceed the toxic dose. Onset of anesthesia may take 5-20 min depending on agent used (lidocaine faster onset than bupivicaine) Exit Step 1 -
Remove tourniquet Remove torniquet after surgery has been completed. Analgesia Analgesia persists until torniquet removed. If a painful procedure was performed additional analgesia may be required after surgery. Special precautions
Potential complications Ischemic damage due to prolonged torniquet use (rare). Bupivacaine can be toxic if it enters the systemic circulation (rapidly). Do not exceed 3 mg/kg total dose. Reasons for treatment failure Torniquet insufficiently tight. Insufficient dose of local anesthetic used. Publications Other sources of information Lumb & Jones (1996) Veterinary Anesthesia. 3rd edn: Williams & Wilkins, Baltimore. pp 432. Vetstream contributor(s) Dr Sheilah Robertson PhD DipACVA DipECVA , Department of Large Animal Clinical Sciences, Box 100136, Gainesville, FL 32610-0136, USA.
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CANIS TEQ00002
Do not use agents combined with epinephrine
Desensitizes the whole area distal to the tourniquet.