Local Anaesthetics

Question 1

What does an adjunctive multimodal analgesic approach mean?

Answer 1

It may be given combined with general anaesthesia

Question 2

True or false:

Local anaesthesia can be used soley or combined with general anaesthesia

Answer 2

True

Question 3

Why are local anaesthetics used?

Answer 3

• Targeted analgesia
• High risk patients where GA not apt
• Part of multi-modal analgesia approach intra-op
• Pre-emptive analgesia
• Widely used in equine and farm animal practice
• Reduce dose of other drugs

Question 4

How do Local Anaesthetics work?

Answer 4

• completely block transmission of pain impulses
• block sodium channels at nerve endings
• Sensory neurons more sensitive
• Tehcnically they produce local analgesia

Question 5

In what order do sensations disappear?

Answer 5

• pain
• cold
• warmth
• touch
• pressure

Question 6

Name the 5 methods of administration

Answer 6

• local infiltration (injection)
• Regional analgesia
• Spinal
• Trans-mucosal
• Trans-cutaneous

Question 7

Name 4 kinds of local anaesthetics

Answer 7

• Emla cream
• Lidocaine (Spray for intubation)
• Splash block
• Intra-testicular
• Eyedrops
• Equine medicine and farm animal medication

Question 8

what are the two kinds of subcutaneous infiltration

Answer 8

ring or line block

Question 9

What kind of local anaesthetic is EMLA

Answer 9

Topical

Question 10

Name 3 drug examples

Answer 10

Lignocaine (+/- adrenaline) 
Bupivacaine 
Lidocaine 
Benzocaine 
Tetracaine 
Amethocaine 
Mepivicaine

Question 11

If used correctly will local anaesthetic give sedative effects?

Answer 11

Only minimal effects

Question 12

Where are local anaesthetics inactivated

Answer 12

The liver - therefore look at a different dose or consider different drug if patient has liver disease

Question 13

How does regional anaesthesia work, who can administer this form of anaesthesia, and name a technique.

Answer 13

Injection into major nerve plexus / close to spinal cord and causes blockage of a relatively large area
Can only be administered by VS
Example: Epidural

Question 14

How is spinal anaesthesia administered

Answer 14

Intra-thecal

Drugs injected into subarachanoid space where they mix with CSF

Question 15

Name 3 forms of topical anaesthesia

Answer 15

Eyes - corneal Drugs: proxymetacaine, amethocaine

Skin: EMLA Drugs: lidocaine and prilocaine

Larynx: Lignocaine spray

Lignocaine gel for urinary catheterisation

Question 16

name 4 risks of local anaesthetics

Answer 16

• May cause nerve damage or permanent loss of function when injected into nerve fibers
• Some local anaesthesia can cause tissue irritation
• Animals may chew the area following recovery (paraesthesia)
• Occasional allergic reactions
• Hypotension may occur especially after epidural anaesthesia
• Systemic toxicity of local anaesthetics
• Depends on rate of uptake / metabolism of drugs
• CNS stimulation may lead to siezures,
• Higher dose may lead to depression which could cause respiratory failure
• Heart contraction force decreases = myocardial depression
• Cats and exotics are very sensitive
• Danger of not calculating total dose given

Question 17

What two local anaesthetics are present in EMLA cream

Answer 17

lidocaine and prilocaine

Question 18

what local anaesthetic is present in larynx spray

Answer 18

lignocaine

Question 19

Which local anaesthetic can be combined with adrenaline

Answer 19

Lignocaine

Question 20

Which local anaesthetic can have anti-arrhythmic effects

Answer 20

Lidocaine