Which laboratory test measures the effectiveness of warfarin?
PTT.
PT/INR.
aPTT.
ACT.
The Correct Answer is B
PT stands for prothrombin time, which is a measure of how long it takes the blood to clot.
INR stands for international normalized ratio, which is a way of standardizing the PT results across different laboratories.
Warfarin is a blood thinner that works by inhibiting the production of vitamin K-dependent clotting factors in the liver.
Therefore, warfarin prolongs the PT and increases the INR. The PT/INR test is used to monitor the effectiveness of warfarin therapy and adjust the dose accordingly.
Choice A is wrong because PTT stands for partial thromboplastin time, which is another measure of blood clotting time, but it reflects the activity of different clotting factors than PT. PTT is used to monitor heparin therapy, not warfarin therapy.
Choice C is wrong because aPTT stands for activated partial thromboplastin time, which is a variation of PTT that uses an activator to speed up the clotting time. Like PTT, aPTT is used to monitor heparin therapy, not warfarin therapy.
Choice D is wrong because ACT stands for activated clotting time, which is a measure of the whole blood clotting time. ACT is used to monitor high-dose heparin therapy during certain procedures, such as cardiac bypass surgery or angioplasty.
The normal ranges for these tests may vary depending on the laboratory and the method used, but generally, they are:
• PT: 10 to 13 seconds
• INR: 0.8 to 1.2 (without warfarin) or 2.0 to 3.0 (with warfarin)
• PTT: 25 to 35 seconds
• aPTT: 30 to 40 seconds
• ACT: 70 to 120 seconds
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is ["A","B"]
Explanation
Pentoxifylline is a medication that improves blood flow and oxygen delivery to the tissues in patients with peripheral vascular disease (PVD), a condition that causes narrowing of the arteries in the legs.Pentoxifylline can help reduce the symptoms of intermittent claudication, which is cramping pain in the legs that occurs with walking and improves with rest.
Choice A is correct because smoking is a major risk factor for PVD and quitting smoking can improve blood flow and prevent further damage to the arteries.
Choice B is correct because prolonged sitting or standing can reduce blood flow to the legs and worsen symptoms of PVD.
Patients should avoid crossing their legs, wearing tight clothing, or exposing their legs to cold temperatures.They should also elevate their legs when resting and move them frequently.
Choice C is wrong because pentoxifylline should be taken on an empty stomach, at least one hour before or two hours after meals, to increase its absorption and effectiveness.
Choice D is wrong because physical activity is beneficial for patients with PVD and intermittent claudication.
Exercise can improve blood circulation, increase muscle strength, reduce pain, and lower cardiovascular risk factors.Patients should be encouraged to walk regularly, as tolerated, and follow a supervised exercise program if available.
Correct Answer is B
Explanation
Nitroglycerin is a medication that dilates the blood vessels and improves blood flow to the heart. It is used to treat angina, a condition that causes chest pain due to reduced oxygen supply to the heart. However, nitroglycerin can lose its effectiveness over time if it is used continuously. This is called tolerance, and it means that the patient will need higher doses of the medication to achieve the same relief. To avoid tolerance, patients who use transdermal nitroglycerin patches are instructed to remove the patch at bedtime and apply a new one in the morning. This creates a nitrate-free interval of about 8 to 12 hours, which allows the body to restore its sensitivity to nitroglycerin.
Choice A is wrong because an allergic response is not a common side effect of nitroglycerin. Some patients may experience skin irritation or rash at the site of application, but this is usually mild and does not require discontinuation of the medication.
Choice C is wrong because overdosage is unlikely with transdermal nitroglycerin patches. The patches deliver a controlled amount of nitroglycerin through the skin over a period of time. The risk of overdosage is higher with other forms of nitroglycerin, such as tablets or sprays, which are taken as needed for acute angina attacks.
Choice D is wrong because forgetting to remove the patch in the morning is not a serious problem. The patch will continue to deliver nitroglycerin until it is removed, but it will not cause harm to the patient. However, it may reduce the effectiveness of the next patch if there is no nitrate-free interval between them.
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