CAPA Nausea & Vomiting Prevention 4 — Questions and Answers
Question 1: Droperidol carries an FDA black box warning related to which adverse effect?
- Hepatotoxicity at standard antiemetic doses
- QTc prolongation and risk of torsades de pointes (Correct answer)
- Severe respiratory depression when combined with opioids
- Anaphylaxis in patients with sulfa allergy
Correct answer: QTc prolongation and risk of torsades de pointes
The FDA issued a black box warning for droperidol in 2001 due to its potential to prolong the QTc interval and cause potentially fatal torsades de pointes.
Question 2: A patient with prolonged QTc interval requires rescue antiemetic therapy. Which drug should be avoided?
- Metoclopramide
- Ondansetron (Correct answer)
- Promethazine
- Dexamethasone
Correct answer: Ondansetron
Ondansetron, like other 5-HT3 antagonists, can prolong the QTc interval and should be used with caution or avoided in patients with existing QTc prolongation.
Question 3: Which mechanism explains why propofol has antiemetic properties?
- It directly blocks 5-HT3 receptors in the gut wall
- It reduces activity in the chemoreceptor trigger zone by modulating GABA and dopamine pathways (Correct answer)
- It inhibits substance P release at the nucleus tractus solitarius
- It directly antagonizes histamine H1 receptors in the vomiting center
Correct answer: It reduces activity in the chemoreceptor trigger zone by modulating GABA and dopamine pathways
Propofol's antiemetic effect is thought to result from modulation of GABA-A receptors and reduction of dopaminergic activity in the chemoreceptor trigger zone.
Question 4: Postoperative opioids contribute to PONV through which primary mechanism?
- Direct irritation of the gastric mucosa causing delayed gastric emptying
- Stimulation of mu-opioid receptors in the chemoreceptor trigger zone and delayed gastric emptying (Correct answer)
- Anticholinergic effects that stimulate the vestibular system
- Histamine release causing direct activation of the vomiting center
Correct answer: Stimulation of mu-opioid receptors in the chemoreceptor trigger zone and delayed gastric emptying
Opioids activate mu-receptors in the chemoreceptor trigger zone and reduce gastrointestinal motility, both of which promote nausea and vomiting.
Question 5: A 28-year-old female non-smoker with a history of PONV is scheduled for thyroidectomy. She has an Apfel score of 3. Per ERAS guidelines, how many prophylactic antiemetic agents should she receive?
- One agent is sufficient for moderate risk
- Two agents targeting different receptors
- Three or more agents in a multimodal regimen (Correct answer)
- No prophylaxis since antiemetics have significant side effects
Correct answer: Three or more agents in a multimodal regimen
Current ERAS and SAMBA guidelines recommend triple or quadruple prophylaxis for patients with Apfel scores of 3-4, targeting multiple receptor pathways.
Question 6: Which statement about metoclopramide as a PONV prophylactic is accurate?
- It is the first-line agent for high-risk patients due to superior efficacy over 5-HT3 antagonists
- Standard doses of 10 mg IV have weak prophylactic efficacy; higher doses increase extrapyramidal risk (Correct answer)
- It is contraindicated in all ambulatory surgical patients due to sedation risk
- It works by blocking serotonin receptors exclusively in the peripheral gut
Correct answer: Standard doses of 10 mg IV have weak prophylactic efficacy; higher doses increase extrapyramidal risk
Metoclopramide 10 mg IV has modest PONV prophylactic efficacy; higher doses increase extrapyramidal side effects, limiting its utility as a primary agent.
Question 7: A PACU nurse administers promethazine 25 mg IV push to a patient with PONV. What serious complication is associated with this route of administration?
- Prolonged QTc and cardiac dysrhythmia
- Severe tissue necrosis if inadvertent intra-arterial or perivascular injection occurs (Correct answer)
- Anaphylaxis due to preservative sensitivity
- Acute hepatic failure with standard doses
Correct answer: Severe tissue necrosis if inadvertent intra-arterial or perivascular injection occurs
IV promethazine carries a black box warning for severe tissue necrosis, gangrene, and amputation risk if administered intra-arterially or if extravasation occurs.
CAPA Nausea & Vomiting Prevention 4
Droperidol carries an FDA black box warning related to which adverse effect?