Local Anesthetic Agents 2 Flashcards
What is part of “multi-modal pain therapy”?
Locoregional anesthesia
Dose reduction of anesthetics can lead to what?
Reduced side effects
Selective nociceptive blockade can provide what type of relief?
Short or long term pain relief
What are 3 formulations of local anesthetics?
- Injectable with preservatives
- Injectable without preservatives
- Topical
Where are topical anesthetics applied?
Skin or mucous membranes
Topical anesthetics are very effective on what 4 areas?
- Eyes
- Nose
- Mouth
- Arytenoids
Topical anesthesia has less effective penetration of what type of skin?
Intact skin
What is EMLA cream?
When is it applied?
How long does it last?
- Eutectic mixture of local anesthetics
- Apply for 1 hour prior to intended use
- Anesthesia for 2 hours
With a low dose of ELMA cream, a cat usually won’t develop what?
Methemoglobinemia
What is used to prevent laryngeal spams during intubation?
Approximately how much is used?
- Lidocaine spray
- 0.1 ml over arytenoids
A subcutaneous injection of small volumes of local anesthetic into tissues is what type of block?
Infiltrative local block
With an infiltrative local block, there is diffusion into where?
Surrounding tissue, anesthetizing nerve fibers and endings.
What are 3 examples of infiltration blocks?
- Incisional line block
- Inverted L block
- Soaker catheters
Which drug is usually used in an incisional line block?
Bupivacaine
Where is an incisional line block injected?
Laterally to incision.
What are the 2 landmarks of an inverted L block?
- Caudal border of Rib 13
- Ventral to lateral processes of lumbar vertebrae
What type of block gets deeper into tissues compared to topical?
Soaker catheter
A delivery tube and sterile multi-pore catheter is placed the the surgical site with what type of block?
Soaker catheter
How is local anesthetic delivered with a soaker catheter?
Intermittent injections or elastomeric reservoir pump
When is a soaker catheter placed?
After surgical procedure has been finished.
What are 2 measurements that need to be made for a soaker catheter?
- Length of catheter required for wound
- Length of catheter need to tunnel injection port under skin to a suitable site for administration
Do you need to suture in a soaker catheter?
No
What is a disadvantage of soaker catheters?
Now have FB in site of incision, may lead to infection.
Should you use a soaker catheter in an active dog?
No
What are 3 indications for use of a soaker catheter?
- Amputation
- Thoracotomy
- Total ear canal ablation
Which out of the following local anesthetic pKa’s would have the fastest onset of action when being delivered in human tissue?
a) pKa 7.5
b) pKa 7.8
c) pKa 8.1
d) pKa 8.4
e) all have similar onset of action
A) pKa 7.5
What is the first sign of toxicity you will witness in an awake animal administered Bupivacaine?
a) Seizures
b) Gastrointestinal ileus
c) Cardiovascular depression
d) Respiratory depression
e) Vomiting
C) Cardiovascular depression
Which nerve fibers are least susceptible to local anesthetics?
a) A delta fiber
b) C fibers
c) A alpha fibers
d) B fibers
e) A beta fibers
C) A alpha fibers (motor fibers)
Injection in the immediate vicinity of individual peripheral nerves or a nerve plexus describes what type of nerve block?
Peripheral nerve block
What are 5 examples of nerve groups that peripheral nerve blocks can be used on?
- Cranial
- Cervical
- Thoracic
- Lumbar
- Sacral
What are 4 examples of cranial nerve blocks commonly used in small animals?
- Infraorbital
- Maxillary
- Mandibular
- Mental
What are 4 locations desensitized by an infraorbital nerve block?
- Upper dental arcade adjacent to injection & rostral
- Upper lip & nose
- Dorsal aspect of nasal cavity
- Soft & hard palate
Where is the infraorbital foramen located?
Dorsal to the rostral edge of the upper fourth premolar.
Could an infraorbital nerve block work for molars?
No
What are 3 examples of indications for an infraorbital nerve block?
- Extraction of canine
- Extraction of incisor
- Extraction of premolar
What are 2 areas desensitized by a maxillary nerve block?
- Ipsilateral upper dental arcade
- Maxilla
Would both a maxillary and infraorbital nerve block be necessary?
No, maxillary will do everything infraorbital will do.
Where is the injection given for a maxillary nerve block?
Dorsal and caudal to the last molar and ventral to the junction of the zygomatic arch and maxilla.