A patient has been prescribed dabigatran (Pradaxa) for atrial fibrillation (AF). Which laboratory test should be monitored while on this medication?
Prothrombin time (PT)
International normalized ratio (INR)
Activated partial thromboplastin time (aPTT)
Platelet count.
Platelet count.
The Correct Answer is C
Activated partial thromboplastin time (aPTT).
Dabigatran (Pradaxa) is a direct oral anticoagulant (DOAC) that inhibits thrombin, a key enzyme in the coagulation cascade.
Dabigatran prolongs the aPTT, which is a measure of the intrinsic and common pathways of coagulation. The aPTT can be used to monitor the anticoagulant effect of dabigatran, although routine monitoring is not required.
Choice A) Prothrombin time (PT) is wrong because PT measures the extrinsic and common pathways of coagulation, which are not affected by dabigatran.
PT is used to monitor warfarin therapy, not dabigatran.
Choice B) International normalized ratio (INR) is wrong because INR is a standardized version of PT that is used to monitor warfarin therapy, not dabigatran.
INR is not affected by dabigatran.
Choice D) Platelet count is wrong because platelet count is a measure of the number of platelets in the blood, which are involved in primary hemostasis.
Platelet count is not affected by dabigatran, which acts on secondary hemostasis.
Normal ranges for these tests are:
• aPTT: 25 to 35 seconds
• PT: 11 to 13.5 seconds
• INR: 0.8 to 1.2
• Platelet count: 150,000 to 450,000 per microliter of blood
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
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.
Correct Answer is C
Explanation
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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