Final answer:
The nurse should monitor for lightheadedness as an adverse effect of furosemide in a patient with heart failure. Furosemide's action in the loop of Henle leads to increased urination and can cause a reduction in blood volume and potential electrolyte imbalances.
Step-by-step explanation:
A nurse caring for a client with heart failure and on furosemide should monitor for a range of potential adverse effects, particularly those related to the drug's potent diuretic action. Furosemide is a loop diuretic that works by inhibiting the reabsorption of sodium (Na+) and chloride (Cl-) ions in the ascending limb of the loop of Henle, which leads to increased urine production. The most relevant adverse effect to monitor for in this patient would be b. Lightheadedness, which can occur due to a decrease in blood volume from the diuretic effect of furosemide that can cause hypotension and electrolyte imbalances.
It is important to correct the initial misconception that furosemide is used to treat hypotension; it is in fact used to treat hypertension and conditions like congestive heart failure where fluid overload is a concern. Furosemide increases the frequency of urination because it effectively reduces fluid retention and helps in managing the fluid overload associated with heart failure. In addition to monitoring for lightheadedness, it would also be important to monitor for signs of electrolyte imbalances, such as low potassium or magnesium levels, which can lead to heart arrhythmias.