Canis ISSN: 2398-2942

Anesthesia: peripheral nerve block - thoracic limb

Synonym(s): Peripheral nerve block of the thoracic limb; PNB

Contributor(s): Luis Campoy, Enzo Vettorato

Introduction

  • Local anesthesia Local anesthesia: overview or loco-regional anesthesia Local anesthesia: intravenous regional anesthesia (IVRA) is a technique to induce a reversible absence of sensation (anesthesia) in a defined part of the body (local).
  • Peripheral nerve block (PNB) is the administration of a local anesthetic drug in proximity of a peripheral nerve to inhibit the conduction of the impulse through it.
  • If an adequate amount of a local anesthetic drug is injected in the proximity of a sensory nerve desensitization of the area served by the relevant nerve will occur. If an adequate amount of a local anesthetic drug is injected in the proximity of a motor nerve paralysis will occur.
  • If the nerve contains both motor and sensory fibers both functions will be impaired.

Uses

  • PNB techniques are used to provide intraoperative anesthesia and, depending on the local anesthetic drug used and the length of the surgery, postoperative analgesia.
  • PNB can be used to provide anesthesia and analgesia and muscle relaxation for both orthopedic and soft tissue surgery of the thoracic limb.

Advantages

  • Cheap and relatively easy to perform (depending on the type of block).
  • Produce intraoperative antinociception and, depending on drugs used and duration of the surgery, postoperative analgesia.
  • Allow performing surgical procedures under sedation Sedation / sedative protocols or lighter plane of anesthesia, therefore decreasing the potential cardio-respiratory effects associated with general anesthesia.
  • Might decrease postoperative opioid consumption producing postoperative analgesia.
  • Minimal systemic side effects have been reported, if not overdosed or accidently injected intravenously.

Disadvantages

  • Failure of the block: if the animal is not fully anesthetized it is advisable assessing the quality and the extension of the block using pin-prick technique or hemostatic forceps before starting the surgery.
  • Depending on type of surgery and animal's demeanour the administration of sedative or general anesthetic in conjunction with local anesthetic technique might be necessary.
  • Toxic plasma levels of a local anesthetic solution can produce neurological and cardiovascular signs especially if injected intravenously. Therefore, aspiration before injection is advisable to decrease the risk of accidental intravascular injection.
  • If the animal is sedated, intraoperative movement can occur even if the local anesthetic technique is 100% successful.
  • Epidural spread could occur performing paravertebral brachial plexus block Anesthesia: brachial plexus block. This might increase the risk of hypotension, therefore monitoring of arterial blood pressure Arterial blood pressure: oscillometric is advisable; or result in phrenic nerve paresis/paralysis, therefore monitoring of ventilation and oxygenation is advisable.

Requirements

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Preparation

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Procedure

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Aftercare

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Rioja E, Sinclair M, Chalmers H et al (2012) Comparison of three techniques for paravertebral brachial plexus blockade in dogs. Vet Anaesth Analg 39 (2), 190-200 PubMed.
  • Campoy L, Bezuidenhout A J, Gleed R D et al (2010) Ultrasound-guided approach for axillary brachial plexus, femoral nerve, and sciatic nerve blocks in dogs. Vet Anaesth Analg 37 (2), 144-153 PubMed.
  • Trumpatori B J, Carter J E, Hash J et al (2010) Evaluation of a mid humeal block of the radial, ulnar, musculocutaneous and medial (RUMM Block) nerves for analgesia of the distal aspect of the thoracic limb in dogs. Vet Surg 39 (7), 785-796 PubMed.
  • Campoy L, Martin-Flores M, Looney A L et al (2008) Distribution of lidocaine-methylene blue solution staining in brachial plexus, lumbar plexus and sciatic nerve blocks in the dog. Vet Anaesth Analg 35 (4), 348-354 PubMed.
  • Lemke K A & Creighton C M (2008) Paravertebral blockade of the brachial plexus in dogs. Vet Clin North Am Small Anim Pract 38 (6), 1231-1241 PubMed.
  • Mahler S P & Adogwa A O (2008) Anatomical and experimental studies of brachial plexus, sciatic, and femoral nerve-location using peripheral nerve stimulation in the dog. Vet Anaesth Analg 35 (1), 80-89 PubMed.
  • Hofmeister E H, Kent M, Read M R et al (2007) Paravertebral block for forelimb anaesthesia in the dog - an anatomical study. Vet Anaesth Analg 34 (2), 139-142 PubMed.
  • Denny N M & Harrop-Griffiths W (2005) Location, location location! Ultrasound imaging in regional anaesthesia. Br J Anaesth 94 (1), 1-3 PubMed.

Other sources of information

  • Campoy L & Read M R (2013)The thoracic limb.In:Small Animal Locoregional Anesthesia and Analgesia.Wiley-Blackwell.
  • Seco O (2013)Ultrasound-guided peripheral nerve blocks.In:Small Animal Locoregional Anesthesia and Analgesia.Wiley-Blackwell.


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