Local Anesthesia

Question 1

What is the basic chemical structure of local anesthetics?

Answer 1

Lipophilic and hydrophilic portion joined by a hydrocarbon chain

Question 2

Order of nerve blockade

Answer 2

1. Beta fibers: preganglionic sympathetic
2. A-delta and C fibers: Pain
3. A-gamma: Proprioception
4. A-Beta: Touch, pressure
5. A-Alpha: Motor

Question 3

What is the pH of local anesthetics?

Answer 3

Weak bases

Question 4

What kind of tissue will increase ionized portion of local anesthetics?

Answer 4

Acidic tissue

Question 5

What are potency, onset, and duration affected by?

Answer 5

pK
Protein binding
Lipid solubility

Question 6

Higher protein binding

Answer 6

longer duration of action

Question 7

Higher lipid solubility

Answer 7

higher potency

Question 8

What are the commonly used amides?

Answer 8

Lidocaine
Bupivacaine
Mepivacaine
Ropivacaine
Prilocaine

Question 9

What is the only local anesthetic that may be given IV?

Answer 9

Lidocaine

Question 10

What are the systemic Lidocaine effects?

Answer 10

Anti-arrhythmic
Decreases MAC
Analgesic
Free radical scavenger 
Improves GI motility

Question 11

What is the local anesthetic with the highest cardiovascular toxicity?

Answer 11

Bupivacaine

Question 12

What are the uses for Mepivacaine?

Answer 12

Nerve blocks

Intra-articular

Question 13

What local anesthetic is safer to use than Bupivacaine?

Answer 13

Ropivacaine

Question 14

What are commonly used esters?

Answer 14

Procaine
Tetracaine
Proparacaine
Benzocaine

Question 15

What are tetracaine and proparacaine used for?

Answer 15

Ophthalmic procedures

Question 16

What is used for a laryngeal spray for intubation?

Answer 16

Benzocaine

Question 17

PABA

Answer 17

Paraaminobenzoic acid

Question 18

What causes allergic reactions?

Answer 18

PABA

Question 19

What local anesthetic is associated with PABA?

Answer 19

Penicillin G

Question 20

Which is more likely to accumulate esters or amides?

Answer 20

Amides

Question 21

Why is epinephrine used in local anesthetics?

Answer 21

prolongs the duration of block

Question 22

What does epinephrine cause?

Answer 22

Vasoconstriction

Question 23

Why is bicarbonate added to local anesthetics?

Answer 23

Faster onset

prolonged duration

Question 24

What causes methemoglobinemia?

Answer 24

Benzocaine
prilocaine
Benzocaine
tetracaine

Question 25

What causes methemoglobinemia in cats?

Answer 25

Benzocaine

Tetracaine

Question 26

What local anesthetic causes chondrotoxicity?

Answer 26

Bupivacaine

Question 27

What local anesthetic is used for equine lameness diagnosis?

Answer 27

Mepivacaine

Question 28

What are the clinical signs of Lidocaine systemic toxicity?

Answer 28

Depression/sedation
twitching
seizures
cardiovascular signs

Question 29

Bier Block

Answer 29

Limb wrapped tightly from distal to proximal and tourniquet is places
Local anesthesia is injected into peripheral vein and diffuses into target tissues

Question 30

When is epidural anesthesia used?

Answer 30

Tail/perineum
Hindlimb
abdominal/thoracic

Question 31

Epidural contraindications

Answer 31

Coagulopathy
Hypovolemia
Infection at injection site
Neoplasia at injection site 
Inability to palpate landmarks 
Sepsis

Question 32

What are the adverse effects of local anesthesia?

Answer 32

Hypotension 
Motor Block/paralysis 
Hematoma 
Infection 
neurotoxicity