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.
Nursing Test Bank
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 B
Explanation
Argatroban is a direct thrombin inhibitor (DTI) that is used as an alternative anticoagulant for patients with heparin-induced thrombocytopenia (HIT) who require urgent surgery. Argatroban has a half-life of about 40 to 50 minutes and is cleared by the liver.The infusion should be stopped at least 4 hours before the surgery to allow adequate time for the anticoagulant effect to wear off.The activated partial thromboplastin time (aPTT) should be monitored before and after the infusion to assess the degree of anticoagulation.
Choice A is wrong because 2 hours is not enough time to stop the argatroban infusion before surgery.
The patient may still have a high risk of bleeding if the aPTT is prolonged.
Choice C is wrong because 6 hours is longer than necessary to stop the argatroban infusion before surgery.
The patient may have a higher risk of thrombosis if the anticoagulation effect is too low.
Choice D is wrong because 8 hours is much longer than necessary to stop the argatroban infusion before surgery.
The patient may have a very low level of anticoagulation and a high risk of thrombosis if the infusion is stopped for too long.
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