PONV (Exam III)

Question 1

What is the most common patient complaint regarding anesthesia? What is the incidence of this compaint?

Answer 1

PONV

• Overal incidence 20-30% (some reach 80%)

Question 2

When does nausea peak in patients post-operatively?
How long does nausea/vomiting typically last post operatively?

Answer 2

Peak: 6 hours
Persists for 24 - 48 hours

Question 3

What are the four major inherent (patient-specific) risk factors for PONV?

Answer 3

• Female
• Non-smoker
• PONV history
• History of motion sickness

Opioid use not an inherent risk factor.

Question 4

What factor is the greatest cause of PONV?

Answer 4

Intraoperative and postoperative opioids.

Question 5

What is the full list of anesthetic-technique risk factors for PONV? (7)

Answer 5

• VAA’s
• Nitrous > 50%
• Opioids
• Neostigmine
• Gastric distention
• Anesthesia duration
• Forced PO fluids prior to discharge

Question 6

What surgeries place a patient at higher risk for development of PONV? (5)

Answer 6

• ENT surgeries
• Neuro surgeries
• laparoscopy/laparotomy
• Breast, plastic, strabismus surgery (girly sx’s)
• Long surgeries

Question 7

Pediatric PONV incidence increases with age until _______.

Answer 7

Pediatric PONV incidence increases with age until puberty

Question 8

Which specific pediatric procedures are noted to have a higher incidence of PONV? (5)

Answer 8

• Adenotonsillectomy
• Strabismus repair
• Hernia repair
• Orchiopexy
• Penile surgeries

Question 9

In pediatrics, how does gender play a role in PONV risk?

Answer 9

In pediatrics, male risk = female risk

unlike with adults, where females have higher risk

Question 10

Will increased O₂ concentrations increase or decrease PONV occurrence?

Answer 10

decrease risk

Question 11

Will adequate hydration increase or decrease PONV occurrence?

Answer 11

decrease risk

Question 12

Will nitrous use increase or decrease PONV occurrence?

Answer 12

increase risk

Question 13

Will neuromuscular blockade reversal with acetylcholinesterase inhibitors increase or decrease PONV occurrence?

Answer 13

Increase risk

neostigmine = ↑ PONV

Question 14

Will minimized motion/ambulation increase or decrease PONV occurrence?

Answer 14

decrease risk

Let patient guide movement based on how they feel.

Question 15

How do volatiles affect risk for PONV?

Answer 15

Increase risk

may supplement with propofol which has antiemetic properties itself

Question 16

Where is the emetic center of the brain located?

Answer 16

Lateral reticular formation of the brainstem

Question 17

Which substances act directly on receptors of the lateral reticular formation of the brainstem?

Answer 17

Trick Question. No substances act directly on the emetic center.

Question 18

Where does afferent input arrive from to the emetic center? (4)

Answer 18

• Pharynx
• GI tract
• Mediastinum
• Afferent nerves of CTZ and 8th CN

Question 19

Where does CNS afferent input to the emetic zone come from?

Answer 19

• Chemoreceptor Trigger Zone (CTZ) of the area postrema
• Vestibular portion of Vestibulocochlear nerve (CN VIII)

Question 20

The CTZ of the area postrema does not have the ______.
What are the implications of this?

Answer 20

Blood brain barrier (BBB)

No BBB means chemicals and drugs in the blood or CSF can trigger N/V.

Question 21

What receptors are located in the Chemoreceptor Trigger Zone? (8)

Answer 21

• Dopamine
• Serotonin
• 5-HT3
• Opioid
• Histamine
• Muscarinic
• Neurokinin-1
• Cannabinoid

Question 22

What drug is the gold standard for PONV prophylaxis and treatment?

Answer 22

Trick question. No single drug is gold standard.

Question 23

Patients (should / should not) receive the same drug for prophylaxis and treatment of PONV.

Answer 23

Should not use the same drug for prophylaxis and treatment

Ex. If ondansetron is used for prophylaxis, use promethazine for treatment

Question 24

When it comes to anti-emetics more is _______ (better or worse)

Answer 24

Better

hit as many receptors as possible

Question 25

Opioid premedication will ______ risk of PONV.
Benzodiazepine premedication may ______ risk of PONV.

Answer 25

Increase

Decrease

Question 26

What induction drug(s) increase risk of PONV? (3)

Answer 26

• VAA’s
• Etomidate
• Ketamine

Question 27

What induction drug(s) decrease risk of PONV?

Answer 27

Propofol

Question 28

What volatile agent is associated with PONV (especially in concentrations greater than 50%)?

Answer 28

Nitrous Oxide

Question 29

One single dose of an opioid is not enough to cause PONV. T/F?

Answer 29

False. A single dose can cause PONV.

Question 30

Greater than ____mg of Neostigmine is associated with increased PONV risk.

Answer 30

> 2.5mg neostigmine

Dose related: ↑ neostigmine = ↑ PONV?.

Question 31

What drug could reduce the PONV associated with neostigmine?

Answer 31

Atropine

Question 32

What is the mechanism of action of PONV induced by neostigmine (anticholinesterases)?

Answer 32

Thought to be muscarinic actions on the GI tract

Question 33

At how many risk factors is PONV prophylaxis indicated?

Answer 33

2 Risk Factors (39%)

Question 34

What PONV treatment would you consider if a patient has low risk of PONV and low risk of medical sequela?

Answer 34

• no prophylaxis
• rescue using 5HT3 antagonist

Question 35

What PONV treatment would you consider if a patient has low risk of PONV and high risk of medical sequela?

Answer 35

• Prophylaxis with 5HT3 antagonist
• Rescue with different class [Phenothiazine, antihistamine, or metoclopramide]

Question 36

What PONV treatment would you consider if a patient has moderate risk of PONV and any risk of medical sequela?

Answer 36

• Prophylaxis with 5HT3 + steroid
• Rescue with different class [Phenothiazine, antihistamine, or metoclopramide]

Question 37

What PONV treatment would you consider if a patient has high risk of PONV and any risk of medical sequela?

Answer 37

• Prophylaxis with 5HT3 + steroid + propofol TIVA + scop
• Rescue with different class [Phenothiazine, antihistamine, or metoclopramide]