A nurse is monitoring a client who is receiving warfarin and has an INR of 4 (0.8 to 1.1). Which of the following medications should the nurse plan to administer?
Vitamin K.
Protamine.
Calcium gluconate.
Epinephrine.
The Correct Answer is A
Choice A rationale
An INR (International Normalized Ratio) of 4.0 indicates that the client's blood is much thinner than the therapeutic range for most conditions (usually 2.0-3.0 for warfarin). This significantly increases the risk of bleeding. Vitamin K is the antidote for warfarin because it is essential for the synthesis of clotting factors (II, VII, IX, X) in the liver. Administering vitamin K reverses the anticoagulant effect of warfarin, reducing the risk of hemorrhage by promoting the production of functional clotting proteins.
Choice B rationale
Protamine sulfate is the antidote for heparin. It works by forming a stable ion pair with heparin, neutralizing its anticoagulant effects. It has no effect on the anticoagulant properties of warfarin, which acts by inhibiting vitamin K epoxide reductase, an enzyme crucial for the regeneration of active vitamin K necessary for clotting factor synthesis. Therefore, protamine is not indicated for warfarin overdose.
Choice C rationale
Calcium gluconate is used to treat hypocalcemia and magnesium toxicity. Calcium plays a vital role in numerous physiological processes, including bone health and muscle function, and is essential for blood coagulation. However, it does not directly counteract the effects of warfarin, which targets vitamin K-dependent clotting factors, and is not the appropriate antidote for an elevated INR.
Choice D rationale
Epinephrine is a potent vasoconstrictor and bronchodilator used in anaphylaxis, cardiac arrest, and severe asthma. It acts on alpha and beta-adrenergic receptors, leading to increased heart rate, blood pressure, and bronchodilation. It has no role in reversing the anticoagulant effects of warfarin and is not indicated for managing an elevated INR.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is D
Explanation
Choice A rationale
Magnesium levels within the normal range (1.3 to 2.1 mEq/L) are important for overall electrolyte balance, but sodium polystyrene sulfonate specifically targets potassium. While hyperkalemia can sometimes be associated with other electrolyte imbalances, a normal magnesium level does not directly indicate a therapeutic response to sodium polystyrene sulfonate, as its primary action is not on magnesium.
Choice B rationale
Calcium levels within the normal range (9 to 10.5 mg/dL) are essential for various physiological functions. Sodium polystyrene sulfonate primarily exchanges sodium ions for potassium ions, not calcium. Therefore, a normal calcium level does not reflect a therapeutic response to the medication, which is specifically aimed at reducing elevated potassium levels.
Choice C rationale
Sodium levels within the normal range (136 to 145 mEq/L) are crucial for fluid balance and neurological function. Sodium polystyrene sulfonate exchanges sodium for potassium, meaning it increases the body's sodium load. While a normal sodium level is desirable, it does not directly indicate the therapeutic efficacy of the medication in reducing potassium.
Choice D rationale
Potassium 4.8 mEq/L (3.5 to 5 mEq/L) indicates a therapeutic response. Sodium polystyrene sulfonate is an ion-exchange resin used to treat hyperkalemia by exchanging potassium ions for sodium ions in the gastrointestinal tract. A potassium level returning to within the normal range, from a previously elevated state, signifies that the medication has effectively lowered the excess potassium.
Correct Answer is C
Explanation
Choice A rationale
A urine output of 240 mL in a 12-hour period translates to 20 mL/hr, which is significantly below the normal physiological range of 30 mL/hr or greater. While low urine output can indicate dehydration, severe oliguria often points to acute kidney injury or severe hypovolemia, not solely dehydration. Normal urine output is generally considered to be 0.5-1 mL/kg/hr.
Choice B rationale
A BUN of 18 mg/dL falls within the normal range of 10 to 20 mg/dL. In dehydration, the kidneys reabsorb more water, leading to a disproportionate increase in BUN relative to creatinine due to increased urea concentration in the tubules, reflecting hypovolemia. A normal BUN value does not indicate dehydration.
Choice C rationale
A weight loss of 0.61 Kg (1.34 lb) in 24 hours is a significant and rapid reduction in body mass. This acute fluid deficit directly reflects a negative fluid balance, indicating a loss of body water. Each kilogram of weight loss approximates 1 liter of fluid loss, making this a clear indicator of dehydration due to fluid volume deficit.
Choice D rationale
A blood pressure of 100/70 mm Hg is within the normal range for many individuals, although it is on the lower side of normotension. While hypotension can be a late sign of severe dehydration, especially orthostatic hypotension, a reading of 100/70 mm Hg alone does not definitively confirm dehydration as the primary cause.
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