L12: Acute Pain Management (Granone)

Question 1

5 processes that make up nociception and pain***

Answer 1

1) transduction
2) transmission
3) modulation
4) projection
5) perception

Question 2

Nociception

Answer 2

Detection of potential or actual damaging stimuli and transmission of info to the brain

5 processes: transduction, transmission, modulation, projection, perception***

Question 3

Nociception vs. pain

Answer 3

Nociceptors (n. Cell endings) initiate the sensation of pain, transduce electrical signals at site of tissue disruption.

Question 4

Fx of spinal cord dorsal horn

Answer 4

• receives electrical signals from primary sensory n. Fibers (alpha-beta, alpha-delta, C fibers)
• signals modulated then sent to brain

Question 5

Fx of brain in processing pain

Answer 5

• receives signals, then initiates physiologic and behavioral responses
• thalamus and somatosensory cortex discriminates pain signals and recognizes, learns, and remembers pain

Question 6

Mechanism of inflammatory mediators and pain amplification

Answer 6

• depolarization of nerve endings
• dec. depolarization threshold of 1ary afferent nerves
• vasodilation, inc. vessel permeability –> inc. inflammatory mediators at injury site

Question 7

Types of pain

Answer 7

1) somatic pain (MS pain)
2) visceral pain
- poorly localized
- mechanical stimuli ie. Stretched viscera
- ischemia
- chemical/thermal stimuli
- change in somatic m. Tone, autonomic responses
- usually referred

Question 8

Adaptive pain = acute pain

Maladaptive pain = chronic pain

Answer 8

:)

Adaptive pain includes inflammatory pain

Question 9

Objective pain assessment includes:

Answer 9

Physiologic variables (HR, RR, BP, rectal temp)

Plasma cortisol, catetcholamine, and beta-endorphin concs.

all are non-specific

Question 10

Therapeutic Pain management ideals

Answer 10

1) Preemptive analgesia (analgesia BEFORE noxious stimuli)

2) Multimodal analgesia (uses >1 modality to obtain additive or synergistic effects)

Question 11

NSAIDs properties

Answer 11

• weak analgesics
• effective anti-inflammatory
• anti-pyretic/endotoxemic/neoplastic
• inhibit COX-1 and COX-2 enzymes impairing prostaglandin synthesis –> analgesia

Question 12

Subjective measures of pain

Answer 12

Numerical rating scales
Simple descriptive scales
Visual analog scale (100cm line)
University of Melbourne pain scale (assess behavioral and physiological indices after surgery in dogs)
CSU pain scale

Question 13

Opioids provide analgesia without loss of:

Answer 13

Touch, proprioception, consciousness

Question 14

Where do opioids act? Where metabolized/excreted?

Answer 14

Act on CNS, periphery, and locally
-activate afferent receptors in periphery

Hepatic metabolism (except rimifentanyl)

Biliary and renal excretion

Question 15

Inflammation increases/decreases expression and synthesis of opioid receptors?

Answer 15

Increases

Question 16

Buprenorphine = partial mu agonist

Torbugesic = kappa agonist and mu opioid antagonist

Answer 16

:)

Question 17

Partial and full opioid reversals

Answer 17

Partial: torb
Full: meloxone

Question 18

binding of mu opioid receptors –>

Answer 18

• Spinal and supraspinal analgesia

- sedation, resp. Depression, bradycardia, depression, drug dependence

Question 19

Kappa opioid receptors vs. mu

Answer 19

Kappa provide spinal analgesia but with less sedation, resp. Depression, and bradycardia

not as useful in severe pain states

Question 20

G-protein coupled receptors inhibit which NT release?

Answer 20

Ach, dopamine, NE, substance P, GABA

Question 21

Epidural opioid effect on motor and SNS fx

Answer 21

Unaltered

-CAN cause urinary retention, resp. Depression, pruritis

Question 22

Opioid side effects

Answer 22

Sedation/CNS depression (dogs)

Excite/dysphoria (cats)
Bradycardia (due to vagal stim.)
Resp. Depress
Panting (resets thermoreg. Center)
HA release (IV morphine, meperidine)
Urinary retention
Cough or laryngeal reflex
Vomiting and defecation
Constipation

Question 23

Local anesthetics can sensitize PNS; they decrease transmission and transduction from occurring by blocking Na channels

Answer 23

:)

Question 24

Factors affecting anesthetic activity

Answer 24

-dose
-site of injection
+/- vasoconstrictors
-mixing of LAs
-physiologic state of patient
-volume, conc.

Question 25

Alpha 2 agonists

Answer 25

• dexmed, xylazine, medetomidine, etc.
• used as analgesic adjuvants
• provide analgesia, sedation, m. Relaxation
• act on G-protein receptors like epi and norepi
• also act on central and peripheral alpha2 receptors to inhibit NT release at dorsal horn, brainstem, and periphery
• cause adverse CV effects
• use in p without systemic dz

Question 26

Adverse effects assoc. with alpha2 agonists

Answer 26

CV effects:

• inc. SVR, then hypotension
• dec. HR, CO, sympathetic activity
• bradyarrhythmias

Resp. Effects:

• dec. RR, tidal volume, End tidal V
• hypoxemia at high dose

GI:

• dec. motility
• nausea/vomiting
• dec. gastric secretions

Renal/endocrine:

• diuresis
• dec. insulin release

Question 27

Ketamine

Answer 27

NMDA antagonist

• prevents central neuronal sensitization and wind-up
• use in severe acute and chronic pain states

Question 28

Tramadol

Answer 28

• atypical mu-opioid agonist
• synthetic centrally acting analgesic
• inhibits uptake of serotonin and Norepi
• mild to mod. Pain only

Question 29

Primary afferent n. Fibers fx

Answer 29

Send info to BRAIN

sensory afferent nerve fibers are dedicated to response of noxious stimuli, and act in pain withdrawal reflex, which doesn’t go to brain