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A patient has been prescribed warfarin in addition to a heparin infusion. The patient asks the nurse why he has to be on two medications. The nurse's response is based on which rationale?
- A. The oral and injection forms work synergistically.
- B. The combination of heparin and an oral anticoagulant results in fewer adverse effects than heparin used alone.
- C. The warfarin is used to reach an adequate level of anticoagulation when heparin alone is unable to do so.
- D. Heparin is used to start anticoagulation so as to allow time for the blood levels of warfarin to reach adequate levels.
Correct Answer: D
Rationale: This overlap therapy is required in patients who have been receiving heparin for anticoagulation and are to be switched to warfarin so that prevention of clotting is continuous. This overlapping is done purposefully to allow time for the blood levels of warfarin to rise, so that when the heparin is eventually discontinued, therapeutic anticoagulation levels of warfarin will have been achieved. Recommendations are to continue overlap therapy of the heparin and warfarin for at least 5 days; the heparin is stopped after day 5 when the international normalized ratio (INR) is above 2.
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A patient has been instructed to take one enteric-coated low-dose aspirin a day as part of therapy to prevent strokes. The nurse will provide which instruction when providing patient teaching about this medication?
- A. Aspirin needs to be taken on an empty stomach to ensure maximal absorption.
- B. Low-dose aspirin therapy rarely causes problems with bleeding.
- C. Take the medication with 6 to 8 ounces of water and with food.
- D. Coated tablets may be crushed if necessary for easier swallowing.
Correct Answer: C
Rationale: Enteric-coated aspirin is best taken with 6 to 8 ounces of water and with food to help decrease gastrointestinal upset. Enteric-coated tablets should not be crushed. Risk for bleeding increases with aspirin therapy, even at low doses.
An elderly patient has had hip surgery and will be receiving heparin, 4000 units subcutaneously every 12 hours. The heparin is available in vials of 5000 units/mL. Calculate how much heparin the nurse will administer for this dose.
Correct Answer: 0.8 mL
Rationale: 5000 units : 1 mL :: 4000 units : x mL; (5000 * x) = (1 * 4000); 5000x = 4000; x = 4000/5000 = 0.8 mL.
A patient has had recent mechanical heart valve surgery and is receiving anticoagulant therapy. While monitoring the patient's laboratory work, the nurse interprets that the patient's international normalized ratio (INR) level of 1.8 indicates: which of these?
- A. The patient is not receiving enough warfarin to have a therapeutic effect.
- B. The patient's warfarin dose is at therapeutic levels.
- C. The patient's intravenous heparin dose is dangerously high.
- D. The patient's intravenous heparin dose is at therapeutic levels.
Correct Answer: A
Rationale: A normal INR (without warfarin) is 1.0. A therapeutic INR for patients who have had mechanical heart valve surgery ranges from 2 to 3.5. For this patient, an INR of 1.8 is not a therapeutic level. Heparin is monitored by aPTT levels, not INR.
The nurse notes in the patient's medication orders that the patient will be starting anticoagulant therapy. What is the primary goal of anticoagulant therapy?
- A. Stabilizing an existing thrombus
- B. Dissolving an existing thrombus
- C. Preventing thrombus formation
- D. Dilating the vessel around a clot
Correct Answer: C
Rationale: Anticoagulants prevent thrombus formation but do not dissolve or stabilize an existing thrombus, nor do they dilate vessels around a clot.
A patient will be taking dabigatran as part of treatment for chronic atrial fibrillation. Which statements about dabigatran are true?
- A. The dose of dabigatran is reduced in patients with decreased renal function.
- B. Bleeding is the most common adverse effect.
- C. Idarucizumab is given as an antidote in cases of uncontrolled bleeding.
- D. Dabigatran levels are monitored by measuring prothrombin time/international normalized ratio (PT/INR) results.
- E. This drug is a prodrug and becomes activated in the liver.
Correct Answer: A,B,C,E
Rationale: Dabigatran is excreted extensively in the kidneys, and the dose is dependent upon renal function. The normal dose is 150 mg twice daily, but it will be given at reduced dosage if renal impairment is present. The most common and serious side effect is bleeding. Dabigatran is a prodrug that becomes activated in the liver. Idarucizumab (Praxbind) is a specific dabigatran antidote that reverses the anticoagulant effects of dabigatran for emergency surgery or in life-threatening or uncontrolled bleeding. Dabigatran levels are not monitored by PT/INR.