The platelet function analyzer
PFA-100® System (Siemens Healthcare Diagnostics) has become a useful tool to
detect abnormalities of primary hemostasis in small
samples of blood. This test system is a microprocessor
controlled instrument which emulates in vitro the platelet
dependent phase of primary hemostasis, while delimiting
the role of the rheological factors.
Basically, the system monitors platelet interaction
on collagen-ADP (COL-ADP) or collagen-epinephrine (COL-EPI)
coated membranes. Samples of citrated blood are aspirated
under controlled flow conditions (shear rate: 4,000-5,000/s)
through a 150 micrometer aperture cut into the membrane.
The platelet hemostatic capacity (PHC) in the blood
sample is indicated by the time required for the platelet
plug to occlude the aperture (closure time), which is
expressed in seconds.
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