Ch. 5: Local Anesthesia Flashcards
Why is local anesthesia used in veterinary dentistry?
To reduce the depth of general anesthesia that is needed and to control pain after the procedure. This can minimize hypoventilation, hypotension, and bradycardia
How do local anesthetics work?
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.
What is the local drug of choice and at what concentration?
Bupivacaine at a 0.5% solution or 5mg/mL
What is the duration of action for local blocks?
6-10 hours
What are the possible, but rare reactions to local anesthetics?
Toxicity to skeletal muscle, anaphylactic reactions, and permanent nerve damage
What is the simple rule of thumb when dosing local anesthetics to avoid toxicity in cats and dogs?
Never exceed 2 mg/kg
Why is epinephrine added to bupivacaine?
To decrease the chance of toxicity
The maximum number of injection sites for local anesthetics during a dental procedure would be how many?
4, one for each quadrant
What are the appropriate amounts of local anesthetics given to cats and dogs per injection site?
Cats and small dogs: 0.1mL
Medium dogs: 0.2mL
Large dogs: 0.3mL
What is a factor that may render local anesthetics less effective?
Inflammation that causes a reduction of the pH of inflamed tissue
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?
0.3mL
What are the 2 types of local anesthesia nerve blocks?
Infiltration blocks and regional blocks
Infiltration blocks are more effective than regional blocks.
True or False?
False; they are the least effective and are usually only used to reduce postoperative discomfort and they only block a specific area
What is the biggest advantage with regional blocks?
They have the ability to block entire quadrants of the mouth
What are the disadvantages to regional blocks?
Transient loss of sensation and function, and possibility of postoperative self-inflicted injury to soft tissues
What is the general technique for regional nerve blocks?
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
What does a rostral maxillary nerve block infiltrate and anesthetize?
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)
What does a caudal maxillary nerve block infiltrate and anesthetize?
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
What is a particular concern with certain animals when doing a caudal maxillary nerve block?
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
What does a rostral mandibular block infiltrate and anesthetize?
It anesthetizes the inferior alveolar nerve via the middle mental foramen. This blocks the incisors, canines, and first two premolars
What is the landmark for a rostral mandibular nerve block?
The mandibular labial frenulum
What should be done if bone is encountered when administering a nerve block?
The needle should be redirected until the needle passes freely into the foramen
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?
The rostral mandibular block
What does a caudal mandibular block infiltrate and anesthetize?
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
There is limited effectiveness to caudal blocks and the rostral blocks are rather recommended.
True or False?
False
What is the landmark for a caudal mandibular block?
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
What is an important component of administering a caudal mandibular nerve block?
It is important the needle tip is located caudal to the foramen and rostral to the angular process of the mandible
A 65-pound dog is needing to have its 408 removed due to an abscessed tooth.What would be the correct regional block?
Caudal mandibular block
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?
Buprenorphine
To mix, 0.05 mL of 300mcg/mL buprenorphine is added to 1 mL of bupivacaine
