Correct Answer: B

Rationale: The correct answer is B: Serum potassium. Spironolactone is a potassium-sparing diuretic, which can lead to hyperkalemia. Monitoring serum potassium levels is crucial to prevent potential complications related to high potassium levels, such as cardiac arrhythmias. Therefore, close monitoring of serum potassium is essential for clients taking spironolactone. Choices A, C, and D are incorrect because spironolactone does not directly impact serum calcium, sodium, or glucose levels significantly. While these values may be monitored for other reasons in a client with heart failure, they are not the primary focus of monitoring when spironolactone is prescribed.

Correct Answer: D

Rationale: The presence of a U wave is often associated with hypokalemia, a possible side effect of diuretic therapy like furosemide. Hypokalemia can lead to U wave formation on an electrocardiogram, making the presence of U waves a concerning finding in clients taking diuretics. Tall, spiked T waves are typically seen in hyperkalemia, not hypokalemia. A prolonged QT interval is more commonly associated with conditions like Long QT syndrome or certain medications, not specifically with diuretics. A widening QRS complex is usually seen in conditions affecting the conduction system of the heart, such as bundle branch blocks, rather than being directly related to diuretic use.

Correct Answer: B

Rationale: In the scenario described, the client's chest pain persists despite three doses of nitroglycerin, indicating a potentially severe cardiac issue like a myocardial infarction. The priority for the nurse in this situation is to involve the healthcare provider promptly. Calling the healthcare provider immediately is essential to ensure timely evaluation and appropriate intervention for the client. Administering more nitroglycerin without further assessment or instructions may not be safe and could delay necessary treatments. Providing oxygen or changing the client's position may offer some comfort but does not address the underlying potentially life-threatening condition, making these options less appropriate as the immediate next best action.

Correct Answer: B

Rationale: Bradycardia is a common sign of digoxin toxicity. Digoxin can cause bradycardia due to its effects on the heart's electrical conduction system. The nurse should closely monitor the client's heart rate for any signs of slowing down, as it can indicate toxicity and potentially lead to serious complications. Hypertension, hyperglycemia, and insomnia are not typically associated with digoxin toxicity. Hypertension is more commonly associated with other conditions or medications, hyperglycemia can be seen in conditions like diabetes or certain medications, and insomnia is not a typical sign of digoxin toxicity.

Correct Answer: B

Rationale: The correct instruction for the nurse to provide to the client prescribed atorvastatin (Lipitor) for hyperlipidemia is to avoid drinking grapefruit juice while taking this medication. Grapefruit juice can interfere with the metabolism of atorvastatin, leading to an increased risk of side effects. It is crucial for the client to adhere to this instruction to ensure the effectiveness and safety of the treatment. Choices A, C, and D are incorrect because taking the medication with breakfast, increasing dietary fiber intake, and avoiding foods high in potassium are not specific instructions related to atorvastatin therapy for hyperlipidemia.