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 B
Explanation
A history of stroke is an absolute contraindication to the administration of a thrombolytic to a patient having an acute myocardial infarction (AMI).This is because thrombolytics can increase the risk of intracranial hemorrhage and worsen the neurological outcome.
Choice A is wrong because history of hypertension is not an absolute contraindication, but a relative one.This means that the benefits of thrombolytic therapy may outweigh the risks in some cases, depending on the severity and duration of hypertension.
Choice C is wrong because history of peptic ulcer disease is also a relative contraindication, not an absolute one.Thrombolytics can increase the risk of gastrointestinal bleeding, but this can be managed with proton pump inhibitors or histamine-2 blockers.
Choice D is wrong because history of diabetes mellitus is not a contraindication at all to thrombolytic therapy.In fact, some studies have shown that diabetic patients with AMI may benefit more from thrombolytic therapy than non-diabetic patients.
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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