A rapid and reproducible test that measures primary platelet-related hemostasis using small amount of anticoagulated whole blood under conditions of high shear, with platelet plug formation. The assay is dependent on von Willebrand factor (vWF) and not fibrinogen.
Employs 3 cartridges, containing:
- Collagen (2 μg equine type I) and epinephrine (10 μg)-coated membrane
- Collagen (2 μg equine type I) and adenosine-diphosphate (50 μg)-coated membrane
- Prostaglandin E1 (5 ng) and ADP (20 μg)-coated membrane
For each cartridge:
- Whole blood (usually 800 μl) is placed into the sample reservoir, and the sample aspirated under a constant vacuum, passing with high shear force through a capillary and a microscopic aperture in the membrane.
- This results in platelet activation, attachment, and aggregation, forming a stable platelet plug at the aperture.
- The instruments report a ‘closure time’, which is the time required for full aperture occlusion and cessation of blood flow.
The instruments are very sensitive to von Willebrand factor defects/deficiencies, and therefore to VWD and to severe platelet function defects, including Bernard Soulier Syndrome or Glanzmann’s Thrombasthenia, but only moderately sensitive to mild platelet defect.
Both PFA-100 and PFA-200 systems employ similar mechanical processes, but the PFA-200 has more advanced software and a modern user interface including a touch screen.
Learn more here.