Siemens PFA-100 System - Principle of Operation

PFA-100 System – Instruction Manual (US) – Version 1.0.1
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6 Description of the analyzer
6
6.6 Principle of operation
Principle of platelet function
analysis
The PFA-100 System is an analyzer and test cartridge system in which the
process of platelet adhesion and aggregation following a vascular injury is
simulated in vitro. Platelet dysfunction detected by the PFA-100 System
may be acquired, inherited, or induced by platelet inhibiting agents.
System functional operation The PFA-100 System allows for rapid evaluation of platelet function on
small samples of anti-coagulated whole blood based on work described by
Kratzer and Born
1
. The single use PFA test cartridge consists of a number
of integrated parts including a capillary, a sample reservoir and a
biochemically active membrane with a central aperture. Anti-coagulated
whole blood is aspirated from the sample reservoir through the capillary and
the aperture, so that platelets are exposed to high shear flow conditions.
At the beginning of a PFA-100 test, trigger solution is dispensed to wet the
membrane and to dissolve the active reagents. During the test, platelets
adhere to the coated membrane. Then, similar to aggregometry
2
, platelets
become activated and release their granule contents. The release of
granule contents is followed by adherence of platelets to each other to form
aggregates. As a measure of platelet function in the PFA-100 System, the
process of platelet aggregation builds a platelet thrombus at the aperture
thereby gradually diminishing and finally arresting the blood flow
2
. The
PFA-100 System determines the time from the start of the test until the
platelet plug occludes the aperture, and reports that time interval as the
Closure Time (CT). The CT is an indicator of platelet function in the
analyzed whole blood sample.
1
Kratzer, MAA: Born, GVR: Simulation of Primary Hemostasis in Vitro. Haemostasis
(1985) 5, 357-362.
2
Born, GVR: Aggregation of blood platelets by adenosine diphosphate and its
reversal. Nature 194:927, 1962.