Laminar Airflow Workbench (LAFW)
A Laminar Airflow Workbench (LAFW) is a sterile compounding device that uses HEPA-filtered unidirectional airflow to provide an ISO Class 5 environment for preparing sterile preparations such as IV admixtures and ophthalmic solutions.
Exam Tip
LAFW = ISO 5 sterile environment. Run 30 min before use. Work 6+ inches inside. Clean back to front with 70% IPA. Horizontal LAFW for non-hazardous, BSC for hazardous drugs. HEPA certified every 6 months.
What Is a Laminar Airflow Workbench?
A Laminar Airflow Workbench (LAFW), also called a laminar flow hood, is a primary engineering control (PEC) used in pharmacy cleanrooms to provide a sterile work environment for compounding sterile preparations. It draws room air through a HEPA filter and directs it in a uniform, unidirectional stream across the work surface.
Types of LAFWs
| Type | Airflow Direction | Use |
|---|---|---|
| Horizontal LAFW | Air flows from back toward the operator | Non-hazardous sterile compounding (most common in pharmacy) |
| Vertical LAFW | Air flows from top downward | Some institutional settings |
| Biological Safety Cabinet (BSC) | Downward flow with exhaust filtration | Hazardous drug compounding (required by USP 800) |
| Compounding Aseptic Isolator (CAI) | Enclosed with HEPA filtration | Alternative to open LAFW |
LAFW Operating Rules
| Rule | Requirement |
|---|---|
| Run time before use | Must run for at least 30 minutes before compounding |
| 6-inch rule | Work at least 6 inches inside the hood opening |
| No blocking airflow | Never block the HEPA filter with objects or hands |
| Clean first | Clean with sterile 70% isopropyl alcohol before each use |
| Nothing between filter and product | Never place anything between the HEPA filter and the critical site |
| Avoid coughing/sneezing | Turn away from the work area if needed |
Cleaning the LAFW
| Step | Detail |
|---|---|
| 1 | Clean with sterile 70% IPA (isopropyl alcohol) |
| 2 | Wipe from cleanest area to dirtiest (back to front, top to bottom) |
| 3 | Use side-to-side motions, overlapping strokes |
| 4 | Allow alcohol to air dry (do not blow or fan) |
HEPA Filter Certification
- HEPA filter must be certified every 6 months
- Certification includes airflow velocity testing and DOP/PAO leak testing
- Work surface provides ISO Class 5 air quality (max 3,520 particles >= 0.5 um per m3)
Exam Alert
The LAFW is a critical topic under the Patient Safety and Quality Assurance domain on the PTCE. Know the 6-inch rule, 30-minute pre-run requirement, cleaning direction (back to front), and that horizontal LAFWs are used for non-hazardous compounding while BSCs are required for hazardous drugs.
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HEPA Filter
A HEPA (High-Efficiency Particulate Air) filter is an air filtration device that removes at least 99.97% of particles 0.3 microns or larger, used in laminar airflow workbenches and cleanrooms to maintain the sterile environment required for compounding sterile preparations.
Aseptic Technique
Aseptic technique is a set of practices and procedures used in sterile compounding to prevent microbial contamination of compounded sterile preparations (CSPs), including proper gowning, hand hygiene, and manipulation within a laminar airflow hood.
USP 795 and USP 797 (Compounding Standards)
USP 795 and USP 797 are United States Pharmacopeia chapters that establish minimum standards for non-sterile compounding (795) and sterile compounding (797), including personnel training, facilities, equipment, and quality assurance requirements.
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