A nurse is reviewing laboratory results for a client who is taking warfarin. Which of the following laboratory tests determines if the dose of medication is within the recommended target range?
Bleeding time
Factor VIII
aPTT
INR
The Correct Answer is D
Choice A reason: Bleeding time assesses platelet function, not warfarin’s anticoagulant effect. Warfarin inhibits vitamin K-dependent clotting factors, unrelated to platelets. Monitoring bleeding time does not reflect therapeutic anticoagulation levels, making it irrelevant for adjusting warfarin doses to prevent thrombosis or bleeding.
Choice B reason: Factor VIII, deficient in hemophilia A, is not affected by warfarin, which targets vitamin K-dependent factors (II, VII, IX, X). Measuring Factor VIII does not indicate warfarin’s efficacy, as it is unrelated to the drug’s mechanism, making it unsuitable for dose monitoring.
Choice C reason: aPTT monitors heparin’s effect on the intrinsic clotting pathway, not warfarin’s action on vitamin K-dependent factors. Warfarin requires INR for therapeutic monitoring, as aPTT is insensitive to its effects, making it inappropriate for assessing warfarin’s anticoagulation range in patients.
Choice D reason: INR standardizes prothrombin time, measuring warfarin’s effect on vitamin K-dependent clotting factors. It ensures therapeutic anticoagulation (e.g., INR 2-3), preventing thrombosis or bleeding. INR is the gold standard for warfarin monitoring, guiding dose adjustments for safe and effective therapy.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
Choice A reason: Applying nitroglycerin ointment in a thin, even layer ensures consistent absorption for angina relief, as specified by dosing guidelines (e.g., using a dosing paper). This maximizes efficacy and minimizes side effects like hypotension, aligning with manufacturer instructions, making it the correct teaching point.
Choice B reason: Applying to the forearm is not standard, as nitroglycerin ointment is typically applied to the chest, upper arm, or back for optimal absorption. Forearm application may reduce effectiveness due to skin thickness, making this an incorrect site choice.
Choice C reason: Applying every 4 hours is incorrect, as nitroglycerin ointment is typically applied 2-3 times daily, with a 12-hour nitrate-free interval to prevent tolerance. This frequency is too frequent and risks side effects, making it an inaccurate instruction.
Choice D reason: Massaging nitroglycerin ointment into the skin is contraindicated, as it alters absorption rates and may cause inconsistent dosing or irritation. The ointment is spread lightly and covered, making this instruction incorrect and potentially harmful for proper administration.
Correct Answer is C
Explanation
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A. Maternal fever Maternal fever typically causes fetal tachycardia (elevated baseline >160/min), not bradycardia. Fever increases maternal metabolic rate and fetal heart rate.
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B. Chorioamnionitis This intrauterine infection also leads to fetal tachycardia, due to inflammatory stress and maternal fever. It is not a cause of bradycardia.
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C. Maternal hypoglycemia ✅ Low maternal glucose levels can reduce fetal energy supply and oxygenation, leading to fetal bradycardia (baseline <110/min). This is a recognized cause of sustained bradycardia.
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D. Fetal anemia Fetal anemia usually results in tachycardia as the fetus compensates for reduced oxygen‑carrying capacity by increasing heart rate. It does not cause bradycardia.
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