Local anaesthetics and dental blocks Flashcards
Describe the mechanism of action of local anaesthetics
Mechanism of action – ionised charged form interacts with receptors
The receptor for LA s is located within the pore of the Na+ channel close to the cytoplasm and only the ionised, charged form of the LA can interact with Rc
What are the different types of LAs?
amides or esters
Amides broken down by liver e.g., lidocaine
esters broken down by plasma cholinesterases e.g., procaine
Give examples of different local anaesthetics?
Procaine
Lidocaine
Bupivacaine
Mepivacaine
Proparacaine
Fill in the table
Give examples of how local anaesthetics can be given in practice
What can be used to prolong to action of LAs?
vasoconstrictors (adrenaline)
- can be risky in areas such as digits, teat etc. (loss of blood supply)
What LA is given before a canine castration?
Pre-incisional block
Intra-testicular block
What are the different ways LA can be given in an ovariohysterectomy?
Direct infiltration of the mesovarium ligament
Lavage of the peritoneal cavity with local anaesthetic
Skin and subcut tissues at incision site also blocked
What type of LA is this?
retro bulba anaesthesia
What types of LA is shown here?
Lumbosacral (L) & sacrococcygeal (R) epidurals
What are the indications of Lumbosacral & sacrococcygeal epidurals?
Tail amputations
Surgeries of the penis or perineal region
Perineal relaxation for puppy/kitten delivery
What dental block is being performed here and what area does it provide analgesia for?
Rostral maxillary (infraorbital)
Provides analgesia for rostral maxillary soft tissues (NOT TEETH/BONE)
Label these nerves
Which nerve innervates the teeth and bone adjacent to the teeth within the maxilla?
Superior alveolar nerve (SAN)
What methods are there to block the maxilla?
Caudal maxillary dental block (intra or extra orally)
What dental block is being shown here?
Mandibular block
What is IVRA?
intra-venous regional analgesia
Describe IVRA
Catheter inserted into vein going to foot
De-sanguinate limb with vetwrap
Place tourniquet proximally and tighten
Remove vetwrap
Inject lidocaine into catheter
Remove catheter and prep for surgery
What block is this?
Bier block
What is the function of a soaker catheter?
Long catheter with small fenestrations to bathe large area in LA
How can nerve blocks be done most accurately?
Using a nerve locator
In what situation can a LA be given into a vessel?
IV lidocaine (NO ADRENALINE)
- decreases opioid use
- decreases MAC
- avoid in cats
What is the benefit of peripheral nerve blocks over epidurals?
reduced risk of urine retention
reduced post-op opioid consumption
How is a patient with local anaesthetic toxicity supported?
intra-lipids
support airways
support seizures
identify and support arrhythmias
