Inhalants (pt.3), Pain management/analgesia, Opioids

Question 1

Name 3 potential theories of how inhalant anesthetics works (the receptors they may act on)

Answer 1

1) GABA
2) two-pore K
3) glycine

Question 2

What is MAC?

Answer 2

the concentration of vapor in the lungs that is needed to prevent movement in 50% of subjects in response to surgical pain stimulus

Question 3

Mac is an index of?

Answer 3

potency

Question 4

Why is MAC hard to translate from research to clinical setting? (3)

Answer 4

1) use only inhalants (don’t account for pre-meds or injectables)
2) use only healthy animals
3) MAC varies by each patient

Question 5

Give the MAC for:

1) ISO
2) SEVO

Answer 5

1) 1.3–1.6

2) 2.3–2.6

Question 6

Two things that increase MAC?

Answer 6

hyperthermia

CNS stimulants

Question 7

4 things that decrease MAC?

Answer 7

pregnancy

hypothermia

extremes of age (young and old)

Other anesthetic agents (pre-med or injectable)

Question 8

Name 7 things that DO NOT change MAC

Answer 8

duration of anesthesia
gender
anticholinergics (atropine)
pH
PaCO2
PaO2
BP

Question 9

Name the beneficial side effects of inhalants as dose increases (4)

Answer 9

1) unconsciousness
2) muscle relaxation
3) loss of nociceptive response
4) loss of sympathetic response

Question 10

Two effects of anesthetics on:

1) CV system
2) respiratory system

Answer 10

CV system:

1) decreases CO (myocardial depression)
2) decreases systemic vascular resistance (vasodilation)

Respiratory:

1) decreases minute ventilation (shallow breaths)
2) decreased response to increased CO2

Question 11

Are inhalants metabolized by the body?

Answer 11

NO

Question 12

Neural process of encoding noxious stimuli

Answer 12

Nociception

Question 13

Name the 5 stages of pain pathway

Answer 13

1) transduction (detection and conversion to AP)
2) transmission (AP to spinal cord)
3) modulation (amplified or suppressed)
4) projection (sent to brain)
5) perception

Question 14

Which area of the brain is involved with perception of pain?

Answer 14

Cortex (thalamus encodes meaning to the pain)

Question 15

Concerning A-delta fibers, describe:

1) myelination status
2) size of receptive field
3) type of pain transmitted

Answer 15

1) lightly myelinated
2) small receptive field
3) rapidly transmits sharp, localized, transient pain

Question 16

Concerning C- fibers, describe:

1) myelination status
2) size of receptive field
3) type of pain transmitted

Answer 16

1) unmyelinated
2) large receptive field
3) slowly transmit generalized, burning, throbbing, and persistent pain

Question 17

Which neurons are involved with:

1) acute, high-intensity stimuli (incisional)
2) tissue injury and inflammation
3) injury to peripheral sensory nerves (neuropathic)

Answer 17

1) A-delta (also C fibers)
2) C fibers
3) A-beta; also C fibers

Question 18

Pain due to a stimulus which does not normally provoke pain

Answer 18

allodynia

Question 19

Two substypes of neuropathic pain; define neuropathic pain

Answer 19

central
peripheral

pain caused by injury to or dysfunction of somatosensory nerves

Question 20

What are 4 signs of neuropathic pain?

Answer 20

hyperalgesia
allodynia
chronicity
Failure of traditional analgesics

Question 21

Glutamate receptors (AMPA & NMDA) in:

1) physiologic state
2) neuropathic state

Answer 21

1) AMPA–active
NMDA–inactive

2) AMPA–sensitized
NMDA–active

Question 22

What 4 categories are used in the AAHA to assess pain?

Answer 22

1) loss of normal behavior
2) expression of abnormal behavior
3) reaction to touch
4) physiologic parameters

Question 23

3 classes of drugs that can be used to treat peri-operative incisional pain?

Answer 23

Opioids
Alpha-2 agonists
Local/regional anesthetics

Question 24

What type of pain can lidocaine be used for?

Answer 24

peripheral neuropathic pain (blocks the bad Na channels)

Question 25

Name 2 drugs used for central neuropathic pain and their MOAs

Answer 25

1) Ketamine–>NMDA receptor antagonist

2) Gabapentin (Ca channel blocker)

Question 26

Drugs that are naturally derived from opium

Answer 26

Opiate

Question 27

Which is a broader term:

Opioid or opiate?

Answer 27

opioid (includes naturals AND synthetics)

Question 28

Name the two clinically relevant opioid receptors and where they exist in highest concentration

Answer 28

1) Mu (MOP)–highest in dorsal horn (lower in brain)

2) Kappa (KOP)–highest in brain (sedation); lower in dorsal horn

Question 29

Which step in the pain transmission pathway do opioids effect and where?

Answer 29

modulation @ dorsal horn & midbrain (descending inhibitory tracts)

Question 30

Differentiate:

1) potency
2) efficacy

Answer 30

1) AMOUNT of substance needed to achieve desired affect

2) ABILITY of substance to achieve a desired affect

Question 31

Three clinical effects of mu agonist?

Answer 31

analgesia
mild sedation
excitement (depending on spp. and dose)

Question 32

Which mu agonist is associated with histamine release?

Answer 32

Morphine

Question 33

Rank the mu agonists (5) by increasing potency

Answer 33

Morphine=methadone
Hydromorphone
Fentanyl
Remifentanil

Fentanyl & Remi are equal in potency

this is also the order of longest to shortest duration of action AND longest to shortest time to onset

Question 34

Why does remifentanil have such a short duration of action?

Answer 34

it’s brokendown by tissue esterases

Question 35

Describe butorphanol’s interactions at the mu and kappa receptors & it’s clinical effects

Answer 35

Mu–antagonist (inhibits full mu agonists)

Kappa–agonist

causes sedation & mild analgesia

Question 36

Naloxone is a ?

Answer 36

opioid ANTAGONIST

Question 37

3 causes of peripheral neuropathic pain

Answer 37

1) sensitization of peripheral nociceptors
2) direct nerve injury
3) alteration in Na channels (lower threshold or spontaneous activation)

Question 38

Opioids stimulate receptors in which 2 areas to cause sedative effects

Answer 38

Midbrain

forebrain

Question 39

13 side effects of opioids

Answer 39

1) decreased ventilation
2) apnea after bolus
3) vomiting
4) reset body temp
5) panting (dogs)
6) cough suppression
7) immunosuppression
8) decreased HR
9) histamine release
10) delayed gastric emptying
11) alterations in peristalsis
12) defecation
13) miosis/mydriasis

Question 40

Buprenorphine is a _____

Answer 40

partial agonist (ceiling effect & reduces effects of full Mu agonists)