Search results
Results from the WOW.Com Content Network
The PFA test result is dependent on platelet function, plasma von Willebrand Factor level, platelet number, and (to some extent) the hematocrit (that is, the percent composition of red blood cells in the sample). The PFA test is initially performed with the Collagen/Epinepherine membrane.
The ristocetin-induced platelet aggregation (RIPA) is an ex vivo assay for live platelet function. It measures platelet aggregation with the help of von Willebrand factor (vWF) and exogenous antibiotic ristocetin added in a graded fashion. [ 1 ]
Multiplate multiple electrode aggregometry (MEA) is a test of platelet function in whole blood. [1] [2] The test can be used to diagnose platelet disorders, [3] [4] [5] monitor antiplatelet therapy, [6] and is also investigated as a potential predictor of transfusion requirements and bleeding risk in cardiac surgery. [7]
The PFA-100 (Platelet Function Assay — 100) is a system for analysing platelet function in which citrated whole blood is aspirated through a disposable cartridge containing an aperture within a membrane coated with either collagen and epinephrine or collagen and ADP. These agonists induce platelet adhesion, activation and aggregation, leading ...
Aspirin inhibits platelet function via the AA pathway while clopidogrel inhibits platelet function via the ADP pathway; thus, this test can be used to determine the degree to which a patient is anticoagulated due to either medication. In this assay, a standard TEG is run using patient's whole blood.
The typical assays are not responsive for the effect of von Willebrand factor or platelet antagonists such as aspirin or thienopyridines (e.g. clopidogrel), and only supratherapeutic doses of GPIIb/IIIa antagonists may influence results. The sensitivity for coagulation factor deficiencies, including those induced by oral anticoagulation, is ...
Light transmission aggregometry is widely accepted as the gold standard diagnostic tool for assessing platelet function, and a result of absent aggregation with any agonist except ristocetin is highly specific for Glanzmann's thrombasthenia. [9] Following is a table comparing its result with other platelet aggregation disorders:
In all forms of the ristocetin assay, the platelets are fixed in formalin prior to the assay to prevent von Willebrand's factor stored in platelet granules from being released and participating in platelet aggregation. Thus, the ristocetin cofactor activity depends only upon high-molecular multimers of the factor present in circulating plasma.