Anesthesia Exam One Learning Objectives

Pain is an unpleasant --- and --- experience associated with or resembling --- ---.

Sensory

Emotional

Tissue damage

True or False: Pain is the same as nociception.

False! Pain is more complex than nociception because it involves emotion/social/psychology shit.

_____: neuronal process encoding noxious stimuli

Nociception

What are the five phases of the pain pathway in order?

Transduction -> transmission -> modulation -> projection -> perception

___: detection of noxious stimuli by nociceptors and conversion to action potential

Transduction

___: Conduction of action potential to spinal cord

Transmission

___: Alteration (amplification or suppression) of action potential

Modulation

___: Conveyance of nociceptive information to brain through spinal cord

Projection

___: Integration, processing, and recognition of nociceptive information

Perception

Where does transduction occur?

Site of injury

Where does transmission occur?

Peripheral nerve to dorsal horn of spinal cord

Where does modulation occur?

Dorsal horn of spinal cord

Where does projection occur?

Spinal cord (spinothalamic tract)

Where does perception occur?

Cerebral cortex

What fiber is MEDIUM-sized, LIGHTLY myelinated with a SMALL receptive field, and has RAPID transmission?

A delta fiber

What fiber is SMALL, UNMYELINATED, has a LARGE receptive field, and SLOW transmission?

C fiber

What TWO fibers are associated with acute high intensity pain?

What kind of pain is this?

A delta and C fibers

Incisional pain

What fiber is associated with tissue inflammation and injury?

What kind of pain is this?

C fiber

Inflammatory pain

What TWO fibers are associated with injury to specific to all peripheral sensory nerves?

What kind of pain is this?

C and A beta fibers

Neuropathic pain

___: Loss of sensation to the entire body or a specific portion of it

Anesthesia

___: Absence of a pain response to stimulation which would normally be painful

Analgesia (haha, anal)

___: an increased response to a normally painful stimulus

Hyperalgesia

___: pain due to a stimulus which does not normally evoke a response

Allodynia

What is the main difference between anesthesia and analgesia?

Anesthesia: loss of consciousness, nociception still occurs

Analgesia: conscious; nociception reduced

__________: pain caused by a primary lesion or dysfunction in the somatosensory nervous system

Neuropathic pain

What are the TWO subtypes of neuropathic pain?

Central and peripheral

Name the FOUR major signs of neuropathic pain.

Hyperalgesia, allodynia, chronicity, failure of analgesics

Name THREE causes of peripheral neuropathic pain.

Peripheral nociception, direct nerve injury, alterations in Na+ channels

_________: an increase in excitability of CNS caused by constant stimulation

Central sensitization

What state are the AMPA and NMDA receptors in during a PHYSIOLOGIC state?

AMPA: active

NMDA: inactive

What state are the AMPA and NMDA receptors in during a NEUROPATHIC state?

AMPA: sensitized

NMDA: active

What is the gold standard for pain assessment?

HA GOT YA! There isn't one.

What are the FOUR categories of the AAHA pain assessment scoring system?

1. Behavioral observation

2. PE/posture and gait

3. Physiological pattern

4. History

What are the FOUR tenants of preventative analgesia?

1. Reduce peripheral nociceptive input

2. Multimodal analgesia

3. Analgesia beyond surgical duration

4. Minimizing sensation

What are THREE classes of drugs utilized to treat perioperative incisional nociception?

Opioids

a2 agonist

Local/regional anesthetics

What drug class is used to treat inflammatory pain?

What fiber is this again?

NSAIDs

C fiber

What drug is used to treat peripheral neuropathic pain?

Lidocaine (Na+ channel blocker)

Name TWO drugs used to treat central neuropathic pain and their MOAs.

Ketamine: NMDA receptor agonist

Gabapentin: Selective Ca+ channel blocker

What drug/NSAID provides lower pain scores at 6 hours post-op?

Carprofen

Name TWO effects of eicosanoids in peripheral tissue as it relates to pain.

Vasodilation (increase pressure + inflammatory cells)

Sensitize pain receptors (increase messengers)

Name TWO effects of eicosanoids in CNS as it relates to pain.

Increase activity of Ca+ channels

Activate microglia

NSAIDs mainly inhibit ---, which decreases the production of --- and ---.

COX

Prostaglandins

Thromboxane

NSAIDs also secondarily inhibit ---, which decreases the production of ---.

LOX

Leukotrienes

What are the THREE housekeeping duties of COX?

Protect gastric mucosa

Protect kidney

Coag platelets

What NSAIDs have inhibitory activity on COX-1? (3)

Aspirin, Ibuprofen, Ketoprofen

What are the THREE beneficial actions of NSAIDs and are they central, peripheral, or both?

Antipyretic (central)

Analgesic (both)

Anti-inflammatory (peripheral)

What are the THREE primary side effects of NSAIDs?

Ulcers, Renal damage, Prolonged clotting

Name THREE conditions in which NSAIDs are contraindicated.

Gastric ulcers (melena, GDV, hematemesis)

Renal disease (insufficient renal blood flow)

Clotting/blood (coag/shock/anemia)

What is phenylbutazone primarily used for?

Musculoskeletal pain in horses

What is flunixin meglumine primarily used for? (2)

Musculoskeletal or visceral pain in horses

Pyrexia, inflammation, or foot rot in cows

What is carprofen primarily used for?

Post-op pain or OA in dogs

What is meloxicam used for?

Post-op pain or OA in dogs/cats

What is the difference between an opiate and opioid?

Opiate: drug naturally derived from opium

Opioid: natural and synthetic opioids

What are the FOUR primary types of opioid receptors?

mu, kappa, delta, NOP

The analgesic effects of opioids occur what pain pathway step?

What TWO locations does this occur?

Modulation

Midbrain

Dorsal horn of spinal cord

What TWO locations does opioid sedative effects occur due to receptor stimulation?

Midbrain and forebrain

Name at least FIVE side effects of opioids. (10)

1. Decreased heart rate

2. Decreased respiration rate

3. Vomiting

4. Defecation

5. Reset body temp (panting in dog; hyperthermia cats)

6. Cough center suppression

7. Immune system suppression

8. Histamine release (morphine IV)

9. Ileus/delayed gastric emptying

10. Miosis/mydriasis (mydriasis in cats)

Where in the body has the highest concentration of MU receptors?

Dorsal horn (spinal cord)

Where in the body has the highest concentration of KAPPA receptors?

Brain

What is different between an agonist, partial agonist, and antagonist?

Agonist: binds receptor and activates it

Partial agonist: binds receptor, less pronounced effect

Antagonist: binds receptor (no effect)

___: amount of substance needed to achieve desired effect

Potency

___: ability of a substance to achieve a desired effect

Efficacy

Name THREE common clinical effects of a mu agonist.

analgesia, mild sedation, excitement (feline/equine)

What is the unique side effect of morphine compared to other mu agonists?

Histamine release when given IV

Rank the five mu agonists in increasing order of potency.

Morphine/Methadone -> Hydromorphone -> Fentanyl -> Remifentanyl

Rank the five mu agonist in decreasing order of duration of action.

Morphine/methadone -> Hydromorphone -> Fentanyl -> Remifentanyl

Rank the five mu agonists in decreasing order of onset.

Morphine/methadone -> Hydromorphone -> Fentanyl -> Remifentanyl

What is the unique property of remifentanil that leads to its ultra-short duration of action?

Broken down by tissue esterase

What is the MOA of buprenorphine?

Partial mu agonist

What is the clinical effect that comes from buprenorphine's properties as a partial agonist?

Ceiling effect but has long duration of action

What is butorphanol's MOA?

kappa agonist, mu antagonist

What are the TWO clinical effects from butorphanol's effects at the kappa receptor?

sedation, mild analgesia

What does butorphanol do at the mu receptor?

Antagonizes (do not give with mu agonist)

What is the major opioid antagonist?

Naloxone

What is the ONLY depolarizing NMBA in vet med?

Succinylcholine

What is the most common non-depolarizing NMBA in vet med?

Atracurium

NMBAs act at the --- --- receptor at the neuromuscular junction.

Nicotinic ACh

How many ACh molecules are needed to active the channel for an NMBA?

2

(Depolarizing/non-depolarizing) NMBAs mimic ACh and cause a discontinuous depolarization, effectively paralyzing the muscle.

Depolarizing

(Depolarizing/non-depolarizing) NMBAs block ACh receptors and prevent its binding, leading to an absence of depolarization and causes paralysis.

Non-depolarizing

True or False: NMBAs cause mild analgesia, unconsciousness, and muscle paralysis,

False! They ONLY cause muscle paralysis.

What method is best to monitor paralysis with NMBAs?

Train of four

A T4/T1 value of --- indicates normal (not blocked), while a value of --- is indicative of paralysis.

1

0.7

What TWO drugs are used to reverse paralysis of NMBAs?

What is their MOA?

Neostigmine, Pyridostigmine

Inhibit acetylcholinesterase

Neostigmine and Pyridostigmine are often administered with --- to prevent ---.

Atropine

Bradycardia

How do you reverse depolarizing NMBAs (succinylcholine)?

You don't (reversal drug prolong effects- only non-depolarizing)

What are the FOUR major reasons for pre-anesthetics?

1. Patient comfort

2. Safety

3. Decrease anesthetic use

4. Physiologic control

What are the FOUR major classes of preanesthetics?

Anticholinergics, tranq, sedatives, analgesics

What drug class competitively inhibits ACh at the muscarinic receptors?

Anticholinergics

--- is the faster/shorter anticholinergic and --- is the slower/longer one.

Atropine

Glycopyrrolate

What is the major contraindications for anticholinergics?

Pre-existing tachycardia or cardiac issue (drug further increases HR)

What drug class is a dopamine antagonist that also blocks a1 receptors?

What is the major drug?

Phenothiazine

Acepromazine

What is the major CV effect of ace?

Vasodilation

You shouldnt use ace in what THREE patients?

Hypovolemic, shock, CV disease

Dexmedetomidine, xylazine, detomidine, and romifidine are all examples of ----------.

Alpha 2 agonists

True or False: Alpha 2 agonists provide sedation AND analgesia

True!

What is the biphasic effect of alpha 2 agonists?

Initial hypertension -> reflex bradycardia (hypotension)

What is used to reverse dexmedetomidine?

Atipamezole

At the cellular level, alpha 2 agonists cause inhibition of --- release from presynaptic nerve endings.

Norepinephrine

Alpha 2 MOA involves the hyperpolarization with what ion?

K+