In heart failure, which medication is commonly used to reduce preload and pulmonary congestion?

Choice A rationale

Serum sodium levels are important to monitor, as furosemide can cause hyponatremia (normal range 135-145 mEq/L). However, muscle weakness and dizziness are more classic signs of hypokalemia, as potassium plays a crucial role in nerve and muscle function. Therefore, potassium is the more critical value to check initially.

Choice B rationale

Furosemide is a loop diuretic that inhibits the reabsorption of sodium and chloride in the loop of Henle, leading to increased excretion of water, sodium, potassium, and chloride. The patient's symptoms of muscle weakness and dizziness are classic manifestations of hypokalemia (normal range 3.5-5.0 mEq/L), making serum potassium the most important lab value to check.

Choice C rationale

While loop diuretics can sometimes affect blood glucose levels, leading to hyperglycemia, this is not a primary concern for the immediate symptoms of muscle weakness and dizziness. These symptoms are much more indicative of an electrolyte imbalance, specifically potassium, which is directly affected by furosemide's mechanism of action.

Choice D rationale

Serum calcium levels can also be affected by furosemide, which can cause hypocalcemia. While hypocalcemia can present with muscle cramps and weakness, hypokalemia is a more common and prominent side effect of loop diuretics. Thus, checking potassium levels is the priority given the reported symptoms.

Choice A rationale

Ethambutol is an antituberculosis medication. The combination of a sore throat and fever can be indicative of a serious and potentially life-threatening adverse effect of the medication, such as hepatotoxicity or bone marrow suppression, which could manifest as agranulocytosis. Continuing the medication would be highly dangerous and could worsen the patient's condition.

Choice B rationale

Sore throat and fever can signal a severe systemic reaction to ethambutol, potentially indicating drug-induced agranulocytosis or hepatotoxicity. Agranulocytosis, characterized by a critically low white blood cell count (normal range for WBC is 4,500 to 11,000 cells/mm), leaves the body vulnerable to overwhelming infection. Immediate discontinuation of the drug and notifying the healthcare provider is the essential nursing action.

Choice C rationale

Increasing the dose of a medication when a patient is exhibiting signs of a potential adverse drug reaction is contraindicated. The symptoms of sore throat and fever suggest a systemic inflammatory or immune response to the drug. Increasing the dose would likely exacerbate the toxicity and further harm the patient, potentially leading to a more severe outcome.

Choice D rationale

A sore throat and fever in a patient on ethambutol could be a sign of a severe adverse drug reaction, not just a simple bacterial infection. While an infection may be present, the primary concern is the potential for bone marrow suppression. Prescribing an antibiotic without a proper diagnosis would be an inappropriate nursing action, as it is outside the scope of practice and would fail to address the underlying issue.