CRNI Infusion-Related Pharmacology 5 — Questions and Answers
Question 1: A patient receiving IV acyclovir complains of burning pain at the infusion site. The nurse observes swelling and pallor around the IV site. What is the priority action?
- Apply a warm compress and slow the infusion rate
- Stop the infusion and assess for extravasation (Correct answer)
- Flush the line with normal saline and continue
- Elevate the extremity and document the finding
Correct answer: Stop the infusion and assess for extravasation
Acyclovir is highly alkaline and vesicant; signs of swelling and pallor indicate possible extravasation, requiring immediate cessation of the infusion and site assessment.
Question 2: Which statement about IV nitroglycerin administration is correct?
- It should be mixed in PVC bags to ensure stability
- Glass bottles and non-PVC tubing must be used to prevent adsorption (Correct answer)
- It can be safely combined with other vasopressors in the same line
- Aluminum-lined tubing is required to prevent photodegradation
Correct answer: Glass bottles and non-PVC tubing must be used to prevent adsorption
Nitroglycerin adsorbs to PVC plastic, significantly reducing drug delivery; glass containers and non-PVC tubing must be used to ensure accurate dosing.
Question 3: A nurse is preparing to administer IV potassium chloride. Which concentration is safe for peripheral IV administration without requiring central line access?
- 40 mEq/100 mL
- 20 mEq/100 mL (Correct answer)
- 60 mEq/100 mL
- 80 mEq/250 mL
Correct answer: 20 mEq/100 mL
Concentrations of 10 mEq/100 mL or less (equivalent to 20 mEq/200 mL) are generally safe peripherally; 20 mEq/100 mL is the maximum recommended concentration for peripheral infusion per most guidelines.
Question 4: When administering IV amiodarone for acute atrial fibrillation, which adverse effect requires IMMEDIATE intervention?
- Mild hypotension with MAP above 65 mmHg
- QTc interval prolongation greater than 500 ms (Correct answer)
- Sinus bradycardia with heart rate of 58 bpm
- Phlebitis at the peripheral IV site
Correct answer: QTc interval prolongation greater than 500 ms
A QTc greater than 500 ms significantly increases the risk of torsades de pointes, a life-threatening arrhythmia requiring immediate prescriber notification and possible drug discontinuation.
Question 5: A patient on total parenteral nutrition (TPN) develops sudden onset of chest pain and dyspnea 30 minutes after the infusion begins. The nurse notes a new cardiac murmur. What complication should be suspected?
- Catheter-related bloodstream infection
- Air embolism from TPN administration (Correct answer)
- Refeeding syndrome with hypophosphatemia
- Hyperglycemic hyperosmolar state
Correct answer: Air embolism from TPN administration
Air embolism can occur with TPN through central lines; presenting with chest pain, dyspnea, and a new 'mill wheel' murmur requires immediate left lateral Trendelenburg positioning and emergency intervention.
Question 6: Which pharmacokinetic principle explains why loading doses are used when initiating continuous IV infusions of drugs like lidocaine?
- To saturate plasma protein binding sites immediately
- To rapidly achieve therapeutic plasma concentrations before steady state (Correct answer)
- To prevent first-pass metabolism in the liver
- To overcome the blood-brain barrier more effectively
Correct answer: To rapidly achieve therapeutic plasma concentrations before steady state
Steady state takes approximately 4-5 half-lives to achieve; a loading dose rapidly fills the volume of distribution to produce therapeutic levels while the maintenance infusion sustains them.
Question 7: A nurse is administering IV metronidazole and notices the patient is also receiving IV phenytoin. Which drug interaction should the nurse anticipate?
- Metronidazole decreases phenytoin absorption
- Metronidazole increases phenytoin serum levels (Correct answer)
- Metronidazole accelerates phenytoin metabolism
- No significant interaction exists between these drugs
Correct answer: Metronidazole increases phenytoin serum levels
Metronidazole inhibits CYP2C9, the primary enzyme responsible for phenytoin metabolism, causing accumulation of phenytoin and increasing the risk of toxicity.
CRNI Infusion-Related Pharmacology 5
A patient receiving IV acyclovir complains of burning pain at the infusion site.
The nurse observes swelling and pallor around the IV site.
What is the priority action?