Ch. 5: Local Anesthesia

Question 1

Why is local anesthesia used in veterinary dentistry?

Answer 1

To reduce the depth of general anesthesia that is needed and to control pain after the procedure. This can minimize hypoventilation, hypotension, and bradycardia

Question 2

How do local anesthetics work?

Answer 2

Nerve cells work by sending small electrical currents through adjacent nerve cells. Local anesthetics work by blocking the channels the sodium ions use to get into the nerve cells. This cuts off any current and therefore any message of pain.

Question 3

What is the local drug of choice and at what concentration?

Answer 3

Bupivacaine at a 0.5% solution or 5mg/mL

Question 4

What is the duration of action for local blocks?

Answer 4

6-10 hours

Question 5

What are the possible, but rare reactions to local anesthetics?

Answer 5

Toxicity to skeletal muscle, anaphylactic reactions, and permanent nerve damage

Question 6

What is the simple rule of thumb when dosing local anesthetics to avoid toxicity in cats and dogs?

Answer 6

Never exceed 2 mg/kg

Question 7

Why is epinephrine added to bupivacaine?

Answer 7

To decrease the chance of toxicity

Question 8

The maximum number of injection sites for local anesthetics during a dental procedure would be how many?

Answer 8

4, one for each quadrant

Question 9

What are the appropriate amounts of local anesthetics given to cats and dogs per injection site?

Answer 9

Cats and small dogs: 0.1mL
Medium dogs: 0.2mL
Large dogs: 0.3mL

Question 10

What is a factor that may render local anesthetics less effective?

Answer 10

Inflammation that causes a reduction of the pH of inflamed tissue

Question 11

A 50-pound dog is needing to have one extraction. What would be the correct amount of local block to use in the site of the block?

Answer 11

0.3mL

Question 12

What are the 2 types of local anesthesia nerve blocks?

Answer 12

Infiltration blocks and regional blocks

Question 13

Infiltration blocks are more effective than regional blocks.

True or False?

Answer 13

False; they are the least effective and are usually only used to reduce postoperative discomfort and they only block a specific area

Question 14

What is the biggest advantage with regional blocks?

Answer 14

They have the ability to block entire quadrants of the mouth

Question 15

What are the disadvantages to regional blocks?

Answer 15

Transient loss of sensation and function, and possibility of postoperative self-inflicted injury to soft tissues

Question 16

What is the general technique for regional nerve blocks?

Answer 16

The needle is advanced slowly, the syringe is drawn back for aspiration, the needle is rotated 90 degrees and aspirated until a full 360 has been accomplished, a small amount is injected and aspiration is repeated. If there is no blood drawn back, the agent can be slowly injected. If blood is present, a new syringe and needle should be obtained and the procedure is repeated

Question 17

What does a rostral maxillary nerve block infiltrate and anesthetize?

Answer 17

It infiltrates the infraorbital nerve as it exits the infraorbital canal. This nerve block will block the incisors, canines, and first three pre-molars (including the maxillary bone and tissue)

Question 18

What does a caudal maxillary nerve block infiltrate and anesthetize?

Answer 18

This block anesthetizes both the maxillary nerve (rostrally becomes the infraorbital nerve) and the sphenopalatine nerve/ganglia. It blocks all of the maxillary teeth and the adjacent bone and soft tissue

Question 19

What is a particular concern with certain animals when doing a caudal maxillary nerve block?

Answer 19

The proper size needle must be used in cats and brachycephalic dogs because the infraorbital canal is very short and therefore it is important to keep the syringe and needle parallel to the dental arch line of the maxilla

Question 20

What does a rostral mandibular block infiltrate and anesthetize?

Answer 20

It anesthetizes the inferior alveolar nerve via the middle mental foramen. This blocks the incisors, canines, and first two premolars

Question 21

What is the landmark for a rostral mandibular nerve block?

Answer 21

The mandibular labial frenulum

Question 22

What should be done if bone is encountered when administering a nerve block?

Answer 22

The needle should be redirected until the needle passes freely into the foramen

Question 23

A patients jaw, rather than the alveolar mucosa, will move slightly if the needle is within the canal.

Which nerve block is this referring to?

Answer 23

The rostral mandibular block

Question 24

What does a caudal mandibular block infiltrate and anesthetize?

Answer 24

It infiltrates the inferior alveolar nerve on the lingual aspect of the mandible as it enters the mandibular canal. This blocks all of the teeth of the mandible on the side of infiltration as well as the adjacent bone and soft tissue

Question 25

There is limited effectiveness to caudal blocks and the rostral blocks are rather recommended.

True or False?

Answer 25

False

Question 26

What is the landmark for a caudal mandibular block?

Answer 26

The notch just dorsal to the angle of the mandible and ventral to the condylar process

An alternative method is to use the lateral canthus of the eyes

Question 27

What is an important component of administering a caudal mandibular nerve block?

Answer 27

It is important the needle tip is located caudal to the foramen and rostral to the angular process of the mandible

Question 28

A 65-pound dog is needing to have its 408 removed due to an abscessed tooth.What would be the correct regional block?

Answer 28

Caudal mandibular block

Question 29

Opioids inhibit pain signals at multiple steps in the pain pathway. Which opioid has been shown to effectively double the analgesic duration when combined with bupivacaine?

Answer 29

Buprenorphine

To mix, 0.05 mL of 300mcg/mL buprenorphine is added to 1 mL of bupivacaine