0Orientation & objectives
This course gives participants a working understanding of how a hollow-fiber hemodialyzer is manufactured — from membrane and fiber bundle through potting, cutting, port assembly, sterilization, and packaging — and where each step intersects the production controls required under the QMSR (21 CFR Part 820 / ISO 13485:2016 § 7.5). Two real, currently-marketed product families, Family A and Family B, are used throughout to ground the material in specified, currently-marketed devices rather than an abstract device class.
Intended audience. Quality-management and quality-assurance consultants who are expert in ISO 13485, TÜV/notified-body audits, and MDSAP, advising dialyzer manufacturers or component suppliers. The course assumes the regulatory-framework knowledge built in the companion QMSR course and concentrates here on the manufacturing side: what actually happens on the production line, and why specific steps draw specific regulatory attention.
Running examples.
- Family A — high-flux only: three sizes, surface areas 1.8–2.3 m², a proprietary polysulfone membrane, oxygen-free gamma sterilization, KUF 99–124 mL/h/mmHg.
- Family B — spans both flux classes on one platform: a high-flux line and a low-flux line, a different proprietary polysulfone membrane, oxygen-free gamma sterilization. Its low-flux and high-flux 1.6 m² variants share an identical surface area but differ roughly 6× in KUF (14 vs. 85 mL/h/mmHg) — proof that flux class is a membrane-engineering choice, not a size choice.
How the course is structured
| Element | Detail |
|---|---|
| Format | Self-paced; approximately 60 minutes |
| Formative questions | 12 multiple-choice, distributed across sections (feedback, not scored) |
| Final assessment | 20 multiple-choice questions; pass mark 80% (16 correct) |
| Currency | Reflects the wiki sources current as of June 2026 |
1The dialyzer: membrane, flux class, and two real products
What a dialyzer is, mechanically
A dialyzer is a bundle of thousands of semipermeable hollow fibers, potted into a housing with two compartments (blood and dialysate) kept separate except across the fiber wall. FDA classifies it under 21 CFR Part 876, Subpart F — as a conventional hemodialysis system (§ 876.5820) or a high permeability system (§ 876.5860, Kuf > 8 mL/hr/mmHg), both Class II, 510(k).
Membrane material
Polysulfone (PSf) and polyethersulfone (PES) dominate current commercial dialyzers — high thermal/mechanical stability and good chemical/pH resistance, offset by hydrophobicity that is typically addressed by blending with polyvinylpyrrolidone (PVP). Both Family A (a proprietary polysulfone) and Family B (a different proprietary polysulfone) are PSf-family membranes — proprietary formulations of the same base polymer chemistry, not different chemistries.
Flux classification — the textbook bands
| Class | KUF (mL/h/mmHg) | β₂-M sieving coefficient | Albumin sieving coefficient |
|---|---|---|---|
| Low flux | <10 | — | 0 |
| High flux | 20–40 | 0.7–0.8 | <0.01 |
| Medium cut-off (MCO) | 40–60 | 0.99 | <0.01 |
| Protein leaking | >40 | 0.9–1.0 | 0.01–0.03 |
| Super high flux | 40–60 | 1.0 | <0.2 |
The two real products against this table
Family B fits the textbook bands closely: its high-flux line reports a β₂-M sieving coefficient of exactly 0.7 (squarely inside the 0.7–0.8 high-flux band); its low-flux line's KUF (11–17 mL/h/mmHg) sits just above the <10 cutoff but is clearly distinct from the 20–40 high-flux band.
Family A does not: its β₂-M sieving coefficient (>0.8) and KUF (99–124 mL/h/mmHg) both exceed the high-flux textbook numbers by a wide margin, yet it is marketed simply as "high flux." The lesson: textbook flux bands are academic/clinical conventions for comparing membranes, not enforced regulatory thresholds. The only regulatory binary cut is FDA's Kuf > 8 mL/hr/mmHg line between § 876.5820 and § 876.5860 — and both Family A and Family B's high-flux line clear that bar easily, while Family B's low-flux line (KUF 11–17) is, perhaps counter-intuitively, also above the FDA's 8 mL/hr/mmHg high-permeability threshold despite being "low flux" by the five-category clinical scheme. This is worth sitting with: FDA's binary regulatory cut and the five-class clinical taxonomy are answering different questions and do not align at the same numeric boundary.
The same platform, two flux classes
Family B's low-flux and high-flux 1.6 m² variants share an identical surface area and blood compartment volume (100 mL), the same membrane material and the same sterilization (oxygen-free gamma) — yet their KUF differs roughly 6-fold (14 vs. 85 mL/h/mmHg). The difference is engineered entirely into the membrane's pore-size distribution, not the device's external dimensions. A participant evaluating a dialyzer design change must therefore look inside the membrane specification, not just the device's outer geometry, to know whether a proposed change affects flux class.