Canis ISSN: 2398-2942

Local anesthesia: overview

Contributor(s): John Dodam, Enzo Vettorato

Definition

  • Local anesthesia or loco-regional anesthesia is a techique to induce a reversible absence of sensation (anesthesia) in a part of the body (local).
  • Depending on the loco-regional anesthetic technique used, local anesthetic drugs decrease transduction or transmission of a noxious stimulus to the spinal cord and to the brain.

Advantages of local anesthetic techniques

  • Cheap and relatively easy to perform.
  • Produce intraoperative antinociception and, depending on drugs used and duration of the surgery, postoperative analgesia.
  • Might decrease postoperative opioid consumption.
  • Allow performing surgical procedures under sedation or lighter plane of anesthesia, therefore decreasing the potential cardio-respiratory effects associated to general anesthesia.
  • Minimal systemic side effects have been reported, if not overdosed or accidently injected intravenously. However hypotension is common after spinal or epidural anesthesia Epidural analgesia technique.

Disadvantages of local anesthetic techniques

  • Failure of the block: if the animal is not anesthetized it is advisable assessing the quality and the extension of the block using pin-prick technique or hemostatic forceps before starting the surgery.
  • Toxic doses can produce neurological and cardiovascular signs especially if injected intravenously.
  • 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.
  • If the animal is sedated, intraoperative movement can occur even if the local anesthetic technique is 100% successful.
  • Systemic hypotension might occur especially after spinal or epidural anesthesia; blood pressure monitoring Blood pressure: direct measurement is therefore highly advisable.
  • Particular care must be exercised if clotting disorders or hypovolemia or sepsis are present, and if a neoplasia is very close to the injection area.

Selection criteria

  • Size and temperament of the animal.
  • Clinical conditions of the animal.
  • Type of surgical procedure.
  • Technical skill of the clinician with the loco-regional technique.
  • Type of surgery.
  • Equipment available.
Print off the owner factsheet All about anaesthesia All about anaesthesia to give to your client.

Classes of local blocks

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Factors affecting duration and latency

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Huuskonen V et al ( 2013) Intratesticular lidocaine reduces the response to surgical castration in dogs. Vet Anaesth Analg 40, 74-82 PubMed.
  • Portela et al (2013) Femoral nerve block: a novel psoas compartment lateral pre-iliac approach in dogs. Vet Anaesth Analg 40, 194-204 PubMed.
  • Vetterato E et al (2013) Retrospective comparison of two peripheral lumbrosacral plexus blocks in dogs undergoing pelvic limb orthopaedic surgery. JSAP 54, 630-637 PubMed.
  • Campoy L et al (2012) Procedural sedation combined with locoregional anesthesia for orthopedic surgery of the pellvic limb in 10 dogs: case series. Vet Anaesth Analg 39, 436-440 PubMed.
  • Campoy L et al (2012b) Comparison of bupivacaine femoral and sciatic nerve block versus bupivacaine and morphine epidural for stifle surgery in dogs. Vet Anaesth Analg 39, 91-98 PubMed.
  • McMillan M W et al (2012) Effect of intratesticular lidocaine on isoflurane requirements in dogs undergoing routine castration. JSAP 53,393-397 PubMed.
  • Trumpatori B J (2010) Evaluation of a midhumeral 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, 785-796 PubMed.
  • Portela et al (2010) Combined paravertebral plexus block and parasacral sciatic block in healthy dogs. Vet Anaesth Analg 37, 531-541 PubMed.
  • Park S A et al (2009) Combination auriculopalpebral nerve block and local anesthesia for placement of a nictitating membrane-to-supertemporal bulbar conjunctiva flap in dogs. JAAHA 45, 164-167 PubMed.
  • Campoy L et al (2008) Distribution of lidocaine-methylene blue solution staining in brachial plexus, lumbar plexus and sciatic nerve blocks in dogs. Vet Anaesth Analg 35, 348-354 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, 80-89 PubMed.

Other sources of information

  • Campoy L, Reed M (2013) Small Animal Locoregional Anesthesia and Analgesia.Wiley-Blackwell.
  • Vickers M D, Morgan M & Spencer P S J (1991) Drugs in Anesthetic Practice. Butterworth Heinemann (Good on the pharmacology of local anesthetic agents).
  • Muir W W, Hubbell J A E & Skarda R (1989) Handbook of Veterinary Anesthesia. Mosby Press (Useful source of diagrams).


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