CAPA Pharmacology & Pain Management 3 — Questions and Answers
Question 1: A PACU patient develops nausea and vomiting 30 minutes after receiving IV morphine. Which antiemetic mechanism is MOST directly targeting opioid-induced nausea?
- 5-HT3 receptor antagonism
- D2 receptor antagonism at the chemoreceptor trigger zone (Correct answer)
- Histamine H1 receptor antagonism
- Muscarinic receptor antagonism
Correct answer: D2 receptor antagonism at the chemoreceptor trigger zone
Opioids stimulate dopamine D2 receptors in the chemoreceptor trigger zone; dopamine antagonists like prochlorperazine or droperidol most directly counter this mechanism.
Question 2: A patient in Phase I recovery has respiratory rate of 8/min and SpO2 of 88% after receiving fentanyl and midazolam. After administering naloxone, the nurse should anticipate which complication?
- Prolonged sedation from residual opioid
- Acute pulmonary edema and hypertensive crisis (Correct answer)
- Paradoxical bradycardia
- Rebound hypoglycemia
Correct answer: Acute pulmonary edema and hypertensive crisis
Naloxone reversal of opioids can cause sudden catecholamine surge leading to acute pulmonary edema, severe hypertension, and cardiac arrhythmias.
Question 3: Dexmedetomidine is used as an adjunct sedative-analgesic in some ambulatory procedures. Its PRIMARY analgesic and sedative mechanism involves which receptor?
- GABA-A receptor potentiation
- Alpha-2 adrenergic receptor agonism (Correct answer)
- NMDA receptor antagonism
- Mu-opioid receptor agonism
Correct answer: Alpha-2 adrenergic receptor agonism
Dexmedetomidine is a highly selective alpha-2 adrenergic agonist that produces sedation via the locus coeruleus and analgesia via spinal cord alpha-2 receptors.
Question 4: A patient with a history of chronic opioid use requires higher-than-expected opioid doses postoperatively to achieve adequate pain control. This phenomenon is BEST described as:
- Opioid toxicity
- Opioid-induced hyperalgesia
- Opioid tolerance (Correct answer)
- Pseudoaddiction
Correct answer: Opioid tolerance
Opioid tolerance is a pharmacological phenomenon where repeated exposure reduces the drug's effect, requiring higher doses to achieve the same analgesic response.
Question 5: Liposomal bupivacaine (Exparel) is used for postoperative analgesia. What distinguishes it from standard bupivacaine regarding its pharmacokinetics?
- Faster onset due to lipid encapsulation
- Extended release providing analgesia up to 72 hours (Correct answer)
- Greater CNS penetration causing more sedation
- Lower maximum concentration reducing efficacy
Correct answer: Extended release providing analgesia up to 72 hours
Liposomal bupivacaine uses DepoFoam technology for sustained release, extending analgesia to 72 hours compared to standard bupivacaine's 8-12 hours.
Question 6: A nurse is preparing to administer IV acetaminophen (Ofirmev) 1000 mg. For which patient population should the dose be reduced to 650 mg every 8 hours?
- Patients over age 65
- Patients weighing less than 50 kg (Correct answer)
- Patients with mild renal impairment (CrCl 30-60 mL/min)
- Patients with a history of asthma
Correct answer: Patients weighing less than 50 kg
IV acetaminophen dosing should be reduced in patients weighing less than 50 kg to 15 mg/kg (max 750 mg) to avoid hepatotoxicity from standard adult doses.
Question 7: Which assessment finding would be a contraindication to administering ketorolac to a postoperative ambulatory patient?
- Age 45 years
- Body weight 95 kg
- Current aspirin use for coronary artery disease (Correct answer)
- Allergy to sulfonamide antibiotics
Correct answer: Current aspirin use for coronary artery disease
Concurrent aspirin use combined with ketorolac significantly increases GI bleeding risk, and patients on aspirin for CAD should generally avoid NSAIDs.
CAPA Pharmacology & Pain Management 3
A PACU patient develops nausea and vomiting 30 minutes after receiving IV morphine.
Which antiemetic mechanism is MOST directly targeting opioid-induced nausea?