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 C
Explanation
Positive inotropy and negative chronotropy.Digoxin is a cardiac glycoside that increases the force of the heart contractions (positive inotropy) and slows down the heart rate (negative chronotropy).
Choice A is wrong because positive chronotropy means increasing the heart rate, which is the opposite of what digoxin does.
Choice B is wrong because negative inotropy means decreasing the force of the heart contractions, which is also the opposite of what digoxin does.
Choice D is wrong because positive chronotropy means increasing the heart rate, which is not what digoxin does.
Digoxin is used to treat heart failure and atrial fibrillation, a type of irregular heartbeat.It has a narrow therapeutic window, meaning that the dose must be carefully adjusted to avoid toxicity or ineffectiveness.
Correct Answer is D
Explanation
This is because digoxin can cause bradycardia (slow heart rate) as a side effect, which can be dangerous and require dose adjustment or discontinuation of the medication.Digoxin helps make the heart beat stronger and with a more regular rhythm by inhibiting sodium-potassium ATPase in cardiac cells.It is used to treat heart failure and atrial fibrillation.
Choice A is wrong because increasing sodium intake can worsen fluid retention and exacerbate heart failure symptoms.Patients with heart failure should follow a low-sodium diet to reduce the workload on the heart.
Choice B is wrong because checking pulse rate for 30 seconds and multiplying result by 2 is not accurate enough to monitor the effects of digoxin.
Patients taking digoxin should check their pulse rate for one full minute before taking each dose and record it daily.If the pulse rate is too fast or too slow, they should contact their provider.
Choice C is wrong because taking digoxin with food may reduce its absorption and effectiveness.Digoxin should be taken on an empty stomach, at least one hour before or two hours after a meal.If nausea occurs, it may be a sign of digoxin toxicity and should be reported to the provider.
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