Lecture 8 Intro to Analgesia Techniques Part 1

Question 1

What are the 6 nsaids given in class

Answer 1

1. Carprofen
2. Deramaxx
3. Meloxicam
4. Robenacoxib
5. Phenylbutazone
6. Flunixin Meglumine

Question 2

1. What species do we use fentanyl intra-op
2. Is it dose dependent MAC sparing?
3. Cause bradycardia or tachycardia?
   
   • How do we treat this?

Answer 2

1. Dogs & cats
2. Dose dependent MAC sparing (up to ~65%)
3. Bradycardia
   
   • Glycopyrrolate, Atropine if also hypotensive

Question 3

What must you monitor with fentanyl

Answer 3

•Monitor EtCO2, IPPV

Question 4

What is MLK?

Answer 4

• Morphine, lidocaine, ketamine
• A Multimodal Analgesia

Question 5

1. What part of pain pathway does morphine work on?
2. Is it better for somatic or visceral pain?

Answer 5

1. transduction, modulation, perception
2. Visceral pain, ‘backbone’ of most/all analgesic protocols

Question 6

1. What part of pain pathway does lidocaine work on?
2. What properties does it have for the MLK combination (its job)

Answer 6

1. transduction*, transmission, modulation
2. Properties:
   
   • Anti-inflammatory, central analgesic properties with CRI
   • ‘Prokinetic’ agent in horses due to anti-inflammatory properties (↓ TNF)
   • Neuroprotection (?)

Question 7

how does lidocaine ↓ cardiac/cerebral ischemia-reperfusion injury ?

Answer 7

↓ cardiac/cerebral ischemia-reperfusion injury by preventing intracellular Na+ overload & through its anti-inflammatory properties

Question 8

1. What type of drug is ketamine
2. How does it block pain?
3. What does it to do MAC of ISO?

Answer 8

1. NMDA receptor antagonist
2. Somatic Pain => bones, joints, ligaments, skin
   
   • ↓ Central sensitization & ‘wind-up’
3. ↓ MAC ISO ~ 10%

Question 9

Explain how central sensitization happens

Answer 9

• Frequent/severe activation of Aδ & C nociceptors =>
  
  • ↑ excitatory neurotransmittors (glutamate, Substance P) =>
  • Activates NMDA, NK, AMPA receptors =>
  • ↑ signal molecules, gene expression, neuroplasticity
• Aβ mechanoreceptors activated => nonpainful stimuli contribute to pain response => 2⁰ hyperalgesia

Question 10

How does Ketamine stop Central Sensitization

Answer 10

Blocks NMDA receptors ↓ central sensitization, wind-up, 2⁰ hyperalgesia, chronic pain

Question 11

How does ketamine cause neuroprotection

Answer 11

• via NMDA blockade
• ↓Ca influx =>
  
  • ↑Cell integrity
  • ↑Cell survival
  • ↑Regeneration

Question 12

Can MLK be bolused?

Answer 12

DO NOT BOLUS!

Question 13

How much does MLK decrease MAC of ISO?

Answer 13

• many patients ~1% ISO
  
  • ↓ MAC of ISO by 45%

Question 14

How do you recover patients on MLK

Answer 14

1. Wean from IPPV, continue to monitor EtCO2
2. 10 minutes O2 support after vaporizer off
3. Monitor SpO2, keep >93-95% with O2 supplementation
4. +/- Partial reversal if prolonged O2 dependence
   
   • 0.1ml (1mg) Butorphanol + .9ml NaCl
     
     • Give in .2ml (.2mg) increments

Question 15

1. What is HLK?
2. What is the difference clinically to MLK?

Answer 15

1. Hydromorphone, lidocaine, ketamine
2. Clinical impression:
   • less sedation
   • more vocalization/dysphoria at recovery

Question 16

1. What is FLK?
2. Why use?

Answer 16

1. Fentanyl, lidocaine, ketamine
2. Use Fentanyl in syringe pump, add LK to IV fluids
   • More control/titration of opioid dosage

Question 17

1. What is FK?
2. What species do you use it in?

Answer 17

1. Fentanyl, Ketamine
2. Cats
   
   • Cats more sensitive to toxic effects of LA

Question 18

1. What species do you give fentanyl post-op?
2. When giving fentanyl post- op what must you monitor?

Answer 18

1. Dogs & cats
2. Monitor cats for hyperthermia

Question 19

1. What must you do to prep for placing a fentanyl patch
2. How long does it take to reach target plasma levels?
3. Does it work all the time?

Answer 19

1. Clip hair, apply to dorsal/lateral thorax
2. Takes 12-24 hrs to reach target plasma levels
   • Need alternate analgesia
3. Inter-individual variability in plasma conc.:
   
   • 30-50% do not achieve analgesic plasma levels (>1 ng/ml)

Question 20

What is important to know about fentanyl patches when it comes to human safety?

Answer 20

• abuse/diversion potential
• Safety with small children, pets
• need proper disposal

Question 21

1. How does Recuvyra™ transdermal Fentanyl work
2. When do you give it?
3. How long does it last?

Answer 21

1. Single application on the skin of the Dorsal interscapular area
   
   • Once in the skin, a slow rate of active ingredient is delivered into the bloodstream
2. 2 – 4 hrs pre-op
3. analgesia 3-4 days

Question 22

1. Recuvyra™ transdermal Fentanyl side effects
2. Is it reversal?

Answer 22

1. ↓ food/water intake, hypothermia, bradycardia
2. Reversible: naloxone

Question 23

1. How does dexmedetomidine cause analgesia?
2. What type of pain does it possibly help?

Answer 23

1. NOT stand alone analgesic
   
   • Synergism with opioids
2. Neuropathic pain

Question 24

What are the benefits of doing an intra-op CRI of Dexmedetomidine

Answer 24

Dose dependent ↓ MAC, up to ~60%

Question 25

Downfalls of using intra-op CRI of Dexmedetomidine

Answer 25

• Higher doses => lower HR, higher MAP
• High incidence 2⁰ AV block, especially at higher doses
• Patients may experience ‘sudden arousal’ after acoustic stimulation (usually at recovery)

Question 26

In what cases do you do a post-op CRI in dogs

Answer 26

1. Multi-trauma cases,
2. high anxiety,
3. dysphoria,
4. aggressive

Question 27

What cases will you use MLK or HLK + Dexmedetomidine CRI in Dogs

Answer 27

Multi-trauma cases - Only after CV stable

Question 28

What are some reasons why a painful patient may bite post op?

Answer 28

1. Stress/fear/anxiety as pain associated with all human contact => biting/aggression
2. Opioid tolerance?
   
   • over time the opioids may not work so will be painful
3. Very stressed/fearful patients