PEBC Sterile Preparations and Aseptic Technique — Questions and Answers
Question 1: When preparing a sterile IV admixture in a Laminar Airflow Workbench (LAFW), in which direction should the pharmacist work relative to the HEPA filter to maintain sterility?
- With the HEPA filter behind the pharmacist, directing airflow away from the product
- Directly in front of the HEPA filter, working within the first-air zone closest to the filter (Correct answer)
- As far from the HEPA filter as possible to avoid turbulence from the blower
- Direction is irrelevant as long as the workbench is ISO Class 5 certified
Correct answer: Directly in front of the HEPA filter, working within the first-air zone closest to the filter
In a LAFW, HEPA-filtered 'first air' flows horizontally from the filter toward the operator. Critical sites (needle hubs, vial stoppers) must be placed in the direct airflow path from the filter — within the 'first-air zone' — to ensure sterile air bathes the product before it reaches human hands or room air.
Question 2: According to standards for sterile compounding, what is the maximum Beyond-Use Date (BUD) for a low-risk sterile preparation stored at controlled room temperature?
- 48 hours (Correct answer)
- 14 days
- 30 days
- 90 days
Correct answer: 48 hours
Under USP <797>-aligned Canadian pharmacy standards, low-risk sterile preparations (simple transfers from commercial sterile containers in ISO Class 5) have a maximum BUD of 48 hours at controlled room temperature, 14 days refrigerated, or 45 days frozen.
Question 3: A pharmacist notices that the ISO Class 5 laminar airflow workbench has not been cleaned before beginning IV preparation. What is the correct cleaning sequence?
- 70% isopropyl alcohol (IPA) wipe from front to back, then repeat; no specific sequence needed
- Sterile water wipe first, followed by 70% IPA wipe from back to front, starting from the HEPA filter and working toward the operator (Correct answer)
- 70% IPA wipe from front to back only; the HEPA filter maintains ISO Class 5 air quality regardless
- Bleach solution wipe, then 70% IPA from front to back, then UV light decontamination
Correct answer: Sterile water wipe first, followed by 70% IPA wipe from back to front, starting from the HEPA filter and working toward the operator
The LAFW should be cleaned with a sterile water wipe first (to remove residue), followed by 70% IPA from back to front (HEPA filter side toward the operator) using overlapping strokes. Cleaning back-to-front pushes contaminants outward and away from the sterile field.
Question 4: Which of the following is classified as a High-Alert Medication (HAM) by ISMP Canada that requires extra precautions when compounding sterile preparations?
- Sodium chloride 0.9% (normal saline)
- Concentrated potassium chloride (KCl) injection (Correct answer)
- Dextrose 5% in water (D5W)
- Sterile water for injection
Correct answer: Concentrated potassium chloride (KCl) injection
ISMP Canada classifies concentrated electrolytes, including concentrated potassium chloride (KCl) injection, as High-Alert Medications because they can cause fatal cardiac arrhythmias if administered undiluted or at incorrect concentrations. They require special storage, labelling, and double-checking protocols.
Question 5: When reconstituting a powdered antibiotic for IV infusion, a pharmacist adds diluent to a vial using positive-pressure technique. What problem can result from excessive positive pressure in the vial?
- Incomplete reconstitution of the powder
- Aerosolization or spray of drug content when the needle is withdrawn, creating a contamination and exposure risk (Correct answer)
- Precipitation of the drug due to rapid dilution
- Reduced drug potency due to oxidation from excess air
Correct answer: Aerosolization or spray of drug content when the needle is withdrawn, creating a contamination and exposure risk
Excessive positive pressure in a vial during reconstitution can cause the contents to spray or aerosolize when the needle is withdrawn, creating both a contamination hazard to the sterile field and a potential exposure risk to the compounder. Pressure should be equalized or slight negative pressure maintained.
Question 6: A hospital pharmacist is preparing a batch of total parenteral nutrition (TPN) admixtures. Which component sequence must be followed when mixing TPN to prevent precipitation?
- Add dextrose and amino acids last to prevent osmolarity-related precipitation
- Add calcium and phosphate sequentially with adequate dilution between them; never add them together concentrated (Correct answer)
- Add lipids first to coat the container, then add electrolytes to the lipid emulsion
- Mix all components simultaneously in the bag to ensure uniform distribution
Correct answer: Add calcium and phosphate sequentially with adequate dilution between them; never add them together concentrated
Calcium-phosphate precipitation is a major safety risk in TPN. Calcium and phosphate must be added separately with adequate dilution (using amino acid or dextrose as buffer between additions) and never in concentrated sequence. A precipitate can cause fatal pulmonary emboli if infused.
PEBC Sterile Preparations and Aseptic Technique
When preparing a sterile IV admixture in a Laminar Airflow Workbench (LAFW), in which direction should the pharmacist work relative to the HEPA filter to maintain sterility?