DM1 P7-7 Adjunctive Analgesic Drugs

Question 1

Why might adjunctive analgesics be required in cats?

Answer 1

Adjunctive analgesics may be needed for cats undergoing invasive surgery or with altered pain states, like chronic pain.

Question 2

How does ketamine provide analgesia?

Answer 2

Ketamine is an NMDA receptor antagonist, effective in reducing pain once central sensitization has developed.

Question 3

When is ketamine used for pain management in cats?

Answer 3

Ketamine is used in low doses (sub-anesthetic) by continuous rate infusion (CRI) as an adjunct to opioid-mediated analgesia.

Question 4

How do Alpha-2 agonists contribute to pain management in cats?

Answer 4

Alpha-2 agonists (e.g. medetomidine, dexmedetomidine) provide analgesia, sedation, and anxiolysis when given by continuous rate infusion (CRI).

Question 5

What is a key side effect of Alpha-2 agonists?

Answer 5

Alpha-2 agonists can cause cardiovascular side effects and significantly increase urine production.

Question 6

What are local anesthetics used for in pain management?

Answer 6

Local anesthetics (e.g. bupivicaine, lidocaine) provide analgesia via topical, infiltration, nerve blocks, epidural, or cavity administration.

Question 7

What is the purpose of an epidural with local anesthetic?

Answer 7

Epidural injection of local anesthetic provides caudal abdominal, perineal, and hind limb analgesia.

Question 8

What are wound catheters used for in pain management?

Answer 8

Wound catheters allow local anesthetic to be infused directly into a wound for long-term analgesia through repeated dosing.

Question 9

How are regional nerve blocks used in cats?

Answer 9

Regional nerve blocks, like brachial plexus blocks, desensitize a large area of tissue, such as the forelimb distal to the elbow.

Question 10

How is topical local anesthetic applied for pain relief?

Answer 10

Topical anesthetics like EMLA cream are applied to desensitize the skin for procedures like intravenous catheterization or blood sampling.

Question 11

How do local anaesthetic drugs block pain sensation?

Answer 11

Local anaesthetic drugs block sodium (Na+) channels in nerves, preventing action potential propagation in sensory nerve fibres.

Question 12

What is a common motor side effect of local anaesthetic use?

Answer 12

Local anaesthetics often block motor nerves, which can reduce mobility during the drug’s duration of action.

Question 13

Which local anaesthetic drugs are most commonly used in cats?

Answer 13

Lidocaine and bupivicaine are the most commonly used local anaesthetics in cats.

Question 14

What is the onset and duration of lidocaine?

Answer 14

Lidocaine has a quick onset (2-5 minutes) but a short duration of action.

Question 15

What is the onset and duration of bupivicaine?

Answer 15

Bupivicaine has a longer onset (15-20 minutes) but a longer duration of action (6-8 hours).

Question 16

What is EMLA cream used for in cats?

Answer 16

EMLA cream is used to desensitize the skin before procedures like intravenous catheterization or blood sampling.

Question 17

What are the side effects of local anaesthetic overdose?

Answer 17

Overdose can cause CNS toxicity (dullness, seizures) and cardiovascular toxicity (bradycardia, hypotension, cardiac arrest).

Question 18

What cardiovascular side effects are associated with bupivicaine?

Answer 18

Bupivicaine can cause hypotension, bradycardia, and even cardiac arrest at higher doses.

Question 19

How can local anaesthetic injections cause pain?

Answer 19

Local anaesthetics are weak acids, which can cause pain on injection, especially in the post-operative period.

Question 20

Why should local anaesthetics containing adrenaline not be used on end arterial sites?

Answer 20

Adrenaline causes vasoconstriction, which can lead to tissue ischemia in areas with limited collateral blood supply.

Question 21

How is the larynx desensitized for intubation in cats?

Answer 21

A veterinary-licensed spray (e.g. Intubeaze) or 0.1-0.2 mL of 1% lidocaine can be used to desensitize the larynx.

Question 22

What is EMLA cream used for?

Answer 22

EMLA cream is used to desensitize the skin before procedures like intravenous catheterization or blood sampling.

Question 23

How is infiltration of local anaesthetic used in surgery?

Answer 23

Local anaesthetic is infiltrated around the incision line or a mass before skin closure or excision.

Question 24

What are some examples of specific nerve blocks in cats?

Answer 24

Maxillary, mandibular, intercostal, and digital nerve blocks are used for localized analgesia, such as for dental procedures or chest wall desensitization.

Question 25

What is a retrobulbar nerve block used for?

Answer 25

A retrobulbar block desensitizes the optic nerve for eye enucleation surgery.

Question 26

What is the purpose of a brachial plexus block?

Answer 26

It provides analgesia to the forelimb distal to the elbow, useful for procedures like radial and ulnar fracture repair.

Question 27

What procedures can benefit from epidural analgesia in cats?

Answer 27

Epidurals are used for hind limb, caudal abdominal, perineal, and cranial abdominal procedures.

Question 28

What drugs are typically used in epidural analgesia?

Answer 28

A combination of morphine and a local anaesthetic (e.g. lidocaine or bupivicaine) is injected into the L7-S1 interface.

Question 29

What are the risks of epidural anaesthesia in hypovolemic patients?

Answer 29

Epidurals can cause vasodilation of mesenteric blood vessels, which can lead to hypotension; fluid administration resolves the issue.

Question 30

What is a potential side effect of morphine given epidurally?

Answer 30

Urinary retention can occur, requiring monitoring and possibly urinary catheter placement.