A nurse is assessing a client prior to administering furosemide. For which of the following findings should the nurse withhold the medication and contact the provider?

Furosemide is a potent loop diuretic that facilitates the excretion of water, sodium, and potassium by inhibiting the Na-K-2Cl symporter. Its use is frequently associated with profound electrolyte imbalances, particularly hypokalemia, which can lead to life-threatening cardiac arrhythmias and altered myocardial repolarization. Rationale: A. A widened QRS complex is usually associated with hyperkalemia or bundle branch blocks rather than the hypokalemia caused by furosemide. Since furosemide promotes potassium excretion, it would typically be used to help lower potassium levels in some clinical scenarios. While a widened QRS is a significant finding, it does not represent the specific electrolyte risk associated with the immediate administration of a loop diuretic. B. A blood pressure of 168/74 mmHg indicates hypertension, which is often an indication for, rather than a contraindication to, the administration of furosemide. The diuretic will help reduce the circulating fluid volume, thereby lowering the systemic blood pressure. The nurse should administer the medication as prescribed to treat the elevated pressure, provided the patient is not displaying signs of acute dehydration or shock. C. Inverted T waves on an electrocardiogram are a classic sign of hypokalemia, indicating that the patient's potassium levels are dangerously low. Because furosemide aggressively flushes potassium out of the body, giving it to a patient who is already hypokalemic could lead to fatal ventricular arrhythmias. The nurse must withhold the dose and contact the provider to address the electrolyte deficit before proceeding with diuresis. D. A urinary output of 30 mL over 3 hr is low (10 mL/hr) and may suggest oliguria or renal insufficiency, but it is often the reason furosemide is being given. The drug is intended to stimulate the kidneys to increase urine production in patients with fluid overload. While the nurse should monitor renal function, low output alone is not as immediate a contraindication as the cardiac signs of severe electrolyte depletion.