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14 Cards in this Set
- Front
- Back
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What should be the first test ordered in the evaluation of primary hemostasis and why?
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Platelet Count because it is quick accurate and reproducible.
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What is the threshold for thrombocytopenia?
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150,000 platelets per cubic millimeter of blood
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What level of thrombocytopenia (what platelet value) would you expect spontaneous bleeding in a patient?
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Platelet count less than 10,000 - 20,000
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What platelet count is the threshold to expect severe bleeding in surgery?
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40,000 to 70,000 depending on the source
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What is the normal range for the Ivy bleeding time test?
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2 - 9 minutes
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What is the PFA-100 and how does it work?
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The Platelet Function Analyzer measures the resistance to the passage of platelets through a standardized aperture. It can be used to measure the variation in resistance in the setting of various platelet activators.
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What is platelet aggregometry?
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Using spectrophotometers to measure the degree of platelet aggregation after exposure to ADP, Epi, collagen or ristocetin.
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What is clot retraction?
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It is a measure of platelet function that is qualitative. At 37 degrees Celsius a clot should begin to retract within 2 to 4 hours.
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What does the Prothrombin time evaluate?
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It evaluates coagulation initiated by TF without the participation of factors VIII or IX.
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Activity of which coagulation factors are needed for measurement of Prothrombin Time?
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Factors VII, X, V, II and I
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What is a normal PT?
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10 - 12 seconds
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If the prothrombin time is elevated at least how much enzymatic activity has been lost by a relevant coagulation factor?
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30%
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Prothrombin time is most sensitive to a decrease in factor ____ and least sensitive to factor _____.
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Most sensitive to factor VII and least sensitive to factor II
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If the activity of prothrombin is only 10% of normal, by how much will prothrombin time be increased?
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only 2 seconds
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