Regional and Local Anesthesia

Chapter 12 Regional and Local Anesthesia



GENERAL COMMENTS



• Local dental nerve blocks can be performed in conjunction with general anesthesia for greater pain relief and reduced general anesthetic levels during oral surgery procedures.

• Local anesthetics will also provide a level of early postoperative analgesia.


Advantages of Local Anesthesia



• Provides pain relief during the procedure and postoperatively.1

• Reduces general anesthetic requirements, thus reducing anesthesia gas consumption.

• Decreases the chance of vagally mediated reflex bradycardia.

• If pain is prevented before it is perceived, the amount of other types of pain medication needed can be reduced.


Disadvantages



• Can add additional time to procedure.

• Potential nerve injury.

• Some patients may paw at mouth after waking.

• Patient may bite its tongue after waking.


LOCAL ANESTHETIC AGENTS



• Longer-acting anesthetics, such as 0.5% bupivacaine, can provide analgesia for 6 to 10 hours.

• Lidocaine 2% without epinephrine gives a shorter duration (less than 2 hours).

• Mepivacaine 2% provides a moderate duration (4 hours).1

• Onset time for analgesia is longer with the longer acting agents such as bupivacaine. The onset time for bupivacaine is often as long as 30 minutes, whereas the onset time for lidocaine is only a few minutes. For this reason, it is common to use a 50-50 mixture of long-acting and short-acting local anesthetic agents.

• Local anesthetic agents may be purchased in carpules, which contain 1.8 cc, or in larger multi-dose bottles.

• Local anesthetic agents enter and occupy ion channels in the nerve cell membrane, preventing depolarization and the conduction of pain impulses.


Location for Blocks



• Regional blocks are introduced at the nerve foramen and create anesthesia of the regional teeth and associated soft tissues.

• Local blocks are accomplished by injecting anesthetic into the periodontal space or gingiva surrounding the tooth. Local blocks provide anesthesia only for the limited area directly perfused by local infiltration.

• Blocks can be performed on the infraorbital, mandibular, and mental nerves.


Dosage



• Total maximum dosage of bupivacaine for cats and dogs is 2 mg/kg.3 The total dosage for lidocaine for the dog is 5 mg/kg and 1 mg/kg for the cat.

• Toxic doses are additive. If a mixture of two local anesthetic agents is being used, it is recommended the maximum dosages be reduced by 50% to prevent inadvertent overdosage.

• Bupivacaine is potentially cardiotoxic; therefore, the lowest possible dosage should be used, which should not exceed 2mg/kg as a total cumulative dosage.

• A 5-kg cat could tolerate 10 mg of bupivacaine, or a total of 2 cc (just over one carpule). Generally 0.25 cc per site is adequate.

• A 30-kg dog could tolerate 60 mg of bupivacaine. Generally 1 cc per site is adequate.


Instrumentation



• A 1.5-inch 27-gauge needle, on a dental anesthetic syringe, is designed to be used with the anesthetic carpule and works most effectively.

• Alternatively, a 1-ml syringe with a 27-gauge hypodermic needle can be used to withdraw the anesthetic from the carpule and infiltrate it into the site.

• Regional anesthetic can reduce the level of general anesthetic required.

• With practice, nerve blocks can be performed accurately and can be very efficacious.

• First the carpule is placed in the syringe (Fig. 12-1, A).

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Related posts:

  1. Anesthesia and Pain Management in Dental and Oral Procedures
  2. General Health Safety and Ergonomics in the Veterinary Dental Workplace
  3. Dental Prophylaxis and Periodontal Disease Stages
  4. Periodontal Therapy and Surgery

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Sep 22, 2016 | Posted by in SMALL ANIMAL | Comments Off on Regional and Local Anesthesia

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