OFA

Question 1

Where are opioid receptors located? (4)

Answer 1

1. CNS
2. Supraspinal
3. Spinal
4. Peripheries

Question 2

there’s a prevalence of _____% of unwanted effects of opioids

Answer 2

30%

Question 3

How does opioids affect OSA?

Answer 3

It can exacerbate OSA & increase its severity

Question 4

T/F: tolerance to analgesic can occur after a single dose with opioids

Answer 4

T

Question 5

Which opioid receptor causes bradycardia?

Answer 5

Mu

Question 6

which opioid receptor causes dysphoria?

Answer 6

Kappa

Question 7

Which opioid receptor causes euphoria?

Answer 7

Mu

Question 8

Which opioid receptors cause urinary retention? (2)

Answer 8

Mu
Delta

Question 9

Which opioid receptor inhibition of peristalsis, N/V?

Answer 9

Mu

Question 10

Which opioid receptors cause pruritis? (2)

Answer 10

Mu
Delta

Question 11

Which opioid receptor is least likely to cause dependence?

Answer 11

Kappa

Question 12

Which opioid receptor can you use for anti-shivering?

Answer 12

Kappa

Question 13

T/F: all opioids produce respiratory depression

Answer 13

T

Question 14

Opioids produce a shift to the _____ in the CO2 response curve. What does this mean?

Answer 14

Right

Higher partial pressure of CO2 levels needed to maintain normal respirations

Question 15

How does opioids affect the airway?

Answer 15

They activate the laryngeal adductors & depressed the abductors & pharyngeal constrictors –> upper airway obstruction

Question 16

Describe the difference between desensitization, tolerance, dependence with opioids

Answer 16

Desensitization: acute tolerance
-transient (minutes - hrs)
-disappears at the same time agonist clearance
-involves phosphorylation of receptor

Tolerance: dt sustained (days - weeks) admin of opioids
-reduction in max achievable effect
-right shift of dose–effect curve

Dependence: state of adaption
-withdrawal syndrome produced by cessation of drug exposure or admin of antagonist

Question 17

What is opioid-induced hyperalgesia (OIH)? What causes this

Answer 17

Nociceptive sensitization caused by exposure to opioids

Paradoxical response from a patient receiving opioids –> pain becomes more sensitive to certain painful stimuli

This is caused by chronic opioid consumption –> activation of mu-receptors –> increase effectiveness of glutaminergic synapses at NMDA receptors –> OIH

Question 18

_______ is an opioid known to be associated with enhanced hyperalgesia

Answer 18

Remifentanil

Question 19

What are indications for opioid free anesthesia? (11)

Answer 19

1. Narcotic abuse history
2. Opioid intolerance
3. Morbidly obese pts w/ OSA
4. Hyperalgesia
5. Hx chronic pain
6. Less analgesic requirement postop
7. ERAS
8. Decrease postop N/V
9. Decrease postop pulmonary morbidity
10. Decreased histamine release
11. Patient satisfaction

Question 20

What is an absolute contraindication to opioid free anesthesia?

Answer 20

Allergy to any of the medication’s

Question 21

What are relative contraindications to opioid free anesthesia? (8)

Answer 21

1. Disorder of autonomic failure
2. Cerebrovascular disease
3. critical coronary stenosis/acute coronary ischemia
4. Heart block/extreme bradycardia
5. Non-stabilize hypovolemic shock
6. Polytrauma pts
7. Controlled hypotension for minimum blood loss
8. Elderly pts on BB

Question 22

OFA toolbox (class/dose/importance): ketamine

Answer 22

Class: NMDA antagonist

Dose = less than 0.5mg/kg reduces postop analgesic needs

Importance: has anti-hyperalgesia, anti-allydonic, anti-tolerance effects
-decreases PONV

Question 23

OFA toolbox (class/MOA/dose/importance): Pregabalin/Gabapentin

Answer 23

Class: Gabapentinoids

MOA: Acts on alpha-2 & delta-1 subunits of the presynaptic calcium channels & inhibit neuronal calcium channel influx. –> reduces release of excitatory neurotransmitters (glutamate, substance P, calcitonin gene related peptide) –> suppresses neuronal excitability

Dose:
Pregabalin = 225 - 300mg lowest effective dose
Gabapentin = 600mg (analgesic ceiling affect)

Importance: decreases PONV, pain intensity, opioid consumption, urinary retention, pruritis

Question 24

OFA toolbox (class/dose/importance):

Answer 24

Class:

Dose =

Importance:

Question 25

OFA toolbox (class/MOA/dose/importance): lidocaine

Answer 25

Class: anti arrhythmic MOA: sodium channel blocker --> suppression of spontaneous impulses generated from injured nerve by inhibiting sodium channels, NMDA, & G–protein receptors Dose: Intraop = 100mg or 1.2-2mg/kg bolus --> 1.33 - 3mg/kg/hr infusion up to 24 hrs Importance: has anti-inflammatory, anti-hyperalgesic properties -useful in abdominal sx --> decrease incident of postop ileus

Question 26

OFA toolbox (class/MOA/dose/importance): magnesium sulfate

Answer 26

Class: non-competitive NMDA antagonist MOA: decreases entry of calcium and sodium into cells and prevent efflux of potassium --> prevents depolarization & pain transmission Dose = 30 - 50mg/kg loading dose --> 6 - 20mg/kg/hr infusion until sx end Importance: reduces opioid consumption in the 1st 24 hrs postop

Question 27

OFA toolbox (class/MOA/dose): Dexmedetomidine

Answer 27

Class: Alpha-2 agonsist MOA: Present both presynapse (inhibit NE) and post synapse (inhibit sympathetic activity). Works both centrally and peripherally. In the CNS works at the locus coeruleus in the brainstem via the Medullospinal pathway --> inhibits nociceptive miran and the release of substance P --> activate G protein K channels --> hyperpolarization Dose = 0.5 mcg/kg loading dose over 10 mins --> 0.1 - - 0.3 mcg/kg/hr infusion

Question 28

OFA toolbox (class/MOA): Esmolol

Answer 28

Class: Beta-1 anatagonist (BB) MOA: rt decrease in hepatic metabolism for opioids by BB --> prolong the action of opioids --> reduce opioid requirements

Question 29

What is the optimal plasma concentration of lidocaine for analgesia?

Answer 29

2 - 5 mcg/ml

Question 30

Describe an OFA induction (4). Give med, dose, and time of admin.

Answer 30

10 mins prior: Precedex 0.3 mcg/kg IBW 1 min prior: Lidocaine 1.5 mg/kg (100mg max) Induction: Propofol 2.5mg/kg Hemodynamic stabilization: Mag 40mg/kg IBW

Question 31

What are OFA options for anti-inflammatory agents prior to sx? (2) Whats the dose?

Answer 31

1. Precedex = 10mg 2. Diclofenac = 75 - 150mg

Question 32

With OFA, in the maintenance phase with propofol infusions you will need _______ doses than TIVA requires

Answer 32

Higher

Question 33

What are barriers to OFA? (6)

Answer 33

1. Resistance to change 2. Cost 3. Need for more research 4. Lack of training 5. Insufficient guidelines 6. Limited data