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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.
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A patient is being discharged on anticoagulant therapy. The nurse will include in the patient-education conversation that it is important to avoid herbal products that contain which substance?
- A. Soy
- B. Valerian
- C. Saw palmetto
- D. St. John's wort
Correct Answer: D
Rationale: Capsicum pepper, dong quai, feverfew, garlic, ginger, ginkgo, and St. John's wort are some herbal products that have potential interactions with anticoagulants, especially with warfarin.
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 is receiving heparin therapy as part of the treatment for a pulmonary embolism. The nurse monitors the results of which laboratory test to check the drug's effectiveness?
- A. Bleeding times
- B. Activated partial thromboplastin time (aPTT)
- C. Prothrombin time/international normalized ratio (PT/INR)
- D. Vitamin K levels
Correct Answer: B
Rationale: Ongoing aPTT values are used to monitor heparin therapy. PT/INR is used to monitor warfarin therapy. The other two options are not used to monitor anticoagulant therapy.
The nurse is reviewing new medication orders for a patient who has an epidural catheter for administration of pain medications. One of the orders is for enoxaparin, a low-molecular-weight heparin (LMWH). What is the nurse's priority action?
- A. Give the LMWH as ordered.
- B. Double-check the LMWH order with another nurse, and then administer as ordered.
- C. Stop the epidural pain medication, and then administer the LMWH.
- D. Contact the prescriber because the LMWH cannot be given if the patient has an epidural catheter.
Correct Answer: D
Rationale: LMWHs are contraindicated in patients with an indwelling epidural catheter; they can be given 2 hours after the epidural is removed. This is very important to remember, because giving an LMWH with an epidural has been associated with epidural hematoma.
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.