Contributors: Enzo Vettorato, Claire Waters, Sheilah Ann Robertson

 Species: Feline   |   Classification: Techniques

Introduction Requirements Preparation Procedure Aftercare Outcomes Further Reading

Introduction

  • Intravenous regional anesthesia (IVRA) or Bier block anesthesia is an anesthetic technique that can be used for surgery of the distal part of the thoracic and pelvic limbs. The technique usually involves exsanguination, which forces blood out of the extremity, followed by the application of a tourniquet to stop blood flow. Local anesthetic is then injected intravenously.
  • Because of cats' temperament IVRA is normally performed under general anesthesia General anesthesia: overview or sedation Sedation or sedative protocol.

Uses

  • Useful for producing intraoperative antinociception and decrease the amount of volatile anesthetic necessary to maintain anesthesia.
  • 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

  • Reliable intraoperative antinociception.
  • Simple to perform.
  • Cheap equipment required.

Disadvantages

  • If inadequately sedated or restrained animal may move during procedure (IVRA associated with light general anesthesia should therefore be preferred).
  • Must identify limit of anesthetized area before operating.
  • Prolonged tourniquet placement can produce pain and ischemia.
  • No postoperative analgesia.

Alternative Techniques

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 animal.

Risk assessment

  • The clinician should assess if performing IVRA in a non-sedated (or unsedated) animal or in a sedated or anesthetized animal depending on type and duration of the surgery, animal's demeanour and clinical conditions.

Requirements

Materials Required

Minimum consumables

  • Needle and syringe.
  • Local anesthetic lidocaine Lidocaine (do not exceed 4 mg/kg).
    Do not use agents combined with epinephrine.

Ideal consumables

  • Intravenous cannula/catheter.

Preparation

Pre-medication

  • Sedation or general anesthesia may be required.

Restraint

  • Additional sedation or in some cases general anesthesia required.
  • Neuroleptanalgesia would be a good choice for this technique.
  • Assistant required to restrain animal.

Procedure

Approach

Step 1 - Place tourniquet

  • Position tourniquet around limb, proximal to the surgical site. Tourniquet must be tight enough to occlude arteries and veins.
  • Check that no pulse distal to the tourniquet is present, ie that tourniquet sufficiently tight.
  • Esmarch's bandage might be useful to exsanguinate the limb. If used, the placement of an intravenous catheter before applying Esmarch's bandage can facilitate the intravenous injection of local anesthetic.

Core Procedure

Step 1 - Place intravenous catheter

  • Insert venous catheter with tip distal to tourniquet.

Step 2 - Inject local anesthetic

  • Lidocaine: <2-4 mg/kg.
  • Do not exceed the toxic dose.
  • Onset of anesthesia may take 5-10 min
  • Check for desensitization of the surgical site using a needle or a clamp before starting.

Exit

Step 1 - Remove tourniquet

  • Remove tourniquet slowly after surgery has been completed.
  • Monitoring of ECG ECG: overview and arterial blood pressure Arterial blood pressure: oscillometric is good practice during tourniquet removal especially after prolonged surgery.
    To avoid hematoma formation do not remove cannula until tourniquet is released.

Aftercare

Immediate

Analgesia

  • Analgesia persists until tourniquet removed.
  • If a painful procedure was performed additional analgesia should be administered before tourniquet removal.

Special precautions

Do not leave tourniquet in place for more than 60-90 min.

Potential complications

  • Ischemic damage due to prolonged tourniquet use (rare).
  • Lidocaine should be preferred for IVRA.
  • Do not exceed 4 mg/kg total dose.
    Do not use bupivacaine Bupivacaine as it is cardiotoxic if enters systemic circulation.

Outcomes

Reasons for Treatment Failure

  • Tourniquet insufficiently tight.
  • Insufficient dose of local anesthetic used.

Further Reading

Publications

Refereed papers

Other sources of information

  • Lumb & Jones (1996) Veterinary Anesthesia. 3rd edn: Williams & Wilkins, Baltimore. pp 432.