A nurse is caring for a client who has atrial fibrillation and is receiving warfarin therapy to prevent thromboembolism formation. The nurse should monitor which of the following laboratory values to determine the effectiveness of the medication?
Activated partial thromboplastin time (aPTT)
Prothrombin time (PT)
International normalized ratio (INR)
Platelet count.
The Correct Answer is C
Warfarin is an anticoagulant that inhibits the synthesis of vitamin K-dependent clotting factors. The INR is a standardized measure of the prothrombin time (PT), which reflects the degree of anticoagulation. The therapeutic range for INR is 2 to 3 for most conditions, and higher for some mechanical heart valves.
Choice A) Activated partial thromboplastin time (aPTT) is wrong because it is used to monitor heparin therapy, not warfarin therapy.
Heparin is another anticoagulant that works by activating antithrombin III, which inhibits thrombin and factor Xa. The therapeutic range for aPTT is 1.5 to 2.5 times the normal value, which is 30 to 40 seconds.
Choice B) Prothrombin time (PT) is wrong because it is not a standardized measure of the warfarin effect.
The PT can vary depending on the reagents and methods used by different laboratories. The INR was developed to eliminate this variability and provide a consistent measure of the warfarin effect.
Choice D) Platelet count is wrong because it is not affected by warfarin therapy.
Warfarin does not affect the number or function of platelets, only the clotting factors. Platelet count can be used to monitor other conditions that affect hemostasis, such as thrombocytopenia or thrombocytosis.
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Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is ["A","C"]
Explanation
Heparin is an anticoagulant that inhibits blood clotting and prevents harmful clots from forming in blood vessels.However, heparin can also cause some serious side effects, such as bleeding, bruising, low platelet count, allergic reactions, and osteoporosis.
Therefore, patients who are at a high risk for developing these adverse effects should be monitored closely and have their heparin dose adjusted accordingly.
Choice A is correct because a patient who is post-op day 1 from brain surgery has a high risk of bleeding from the surgical site or intracranially.Heparin can increase this risk and cause life-threatening hemorrhage.
Therefore, this patient should not receive heparin unless absolutely necessary and under strict supervision.
Choice B is wrong because a patient with a pulmonary embolism (PE) is a candidate for heparin therapy.
A PE is a blood clot that blocks the blood flow to the lungs and can cause respiratory failure and death.Heparin can prevent the clot from becoming larger and causing more damage, and also prevent new clots from forming.
Therefore, this patient would benefit from heparin therapy and is not at a high risk of adverse effects.
Choice C is correct because a patient with active peptic ulcer disease (PUD) has a high risk of bleeding from the stomach or duodenum.
PUD is a condition where the lining of the digestive tract is eroded by stomach acid and bacteria.Heparin can worsen this condition and cause ulcer bleeding or perforation.
Therefore, this patient should avoid heparin therapy unless absolutely necessary and under strict supervision.
Choice D is wrong because a patient with uncontrolled atrial fibrillation (AF) is a candidate for heparin therapy.
AF is an irregular heartbeat that can cause blood clots to form in the heart chambers and travel to other organs, such as the brain or lungs.Heparin can prevent these clots from forming and reduce the risk of stroke or PE.
Therefore, this patient would benefit from heparin therapy and is not at a high risk of adverse effects.
Normal ranges of heparin depend on the type of heparin used (unfractionated heparin or low molecular weight heparin), the method of administration (intravenous or subcutaneous), and the indication for use (prophylaxis or treatment).Generally, the therapeutic range for heparin level is 0.3 - 0.7 U/mL, measured by anti-Xa assay.However, this range may vary depending on the pregnancy stage and the type of heparin used.The dose of heparin should be individualized according to the results of suitable laboratory tests and clinical response.
Correct Answer is C
Explanation
This is because argatroban is a direct thrombin inhibitor that can be used as an alternative anticoagulant for patients with heparin-induced thrombocytopenia (HIT).HIT is an immune-mediated disorder that occurs when antibodies form against heparin and platelet factor 4, leading to platelet activation and thrombosis.The diagnosis of HIT is based on clinical criteria and laboratory tests.
Choice A is wrong because warfarin is a vitamin K antagonist that interferes with the synthesis of clotting factors II, VII, IX, and X.Warfarin is contraindicated in patients with HIT because it can worsen the thrombotic complications and cause skin necrosis.Warfarin should only be started after the platelet count has recovered and the patient is adequately anticoagulated with a non-heparin agent.
Choice B is wrong because clopidogrel is an antiplatelet agent that inhibits the ADP receptor on platelets, preventing their aggregation.Clopidogrel is not effective for the treatment of HIT, as it does not target the underlying mechanism of thrombin generation.Clopidogrel may also increase the risk of bleeding in patients with HIT.
Choice D is wrong because alteplase is a fibrinolytic agent that converts plasminogen to plasmin, which breaks down fibrin clots.Alteplase is not indicated for the treatment of HIT, as it does not prevent further thrombosis and may cause severe bleeding complications.Alteplase may be used as a last resort for life-threatening thrombosis in patients with HIT who do not respond to other therapies.
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