Which diuretic is commonly used to treat pulmonary edema?

• A. Mannitol
• B. Acetazolamide
• C. Hydrochlorothiazide
• D. Furosemide

Answer: (D)

In pulmonary edema, the priority is rapid removal of excess fluid and a quick drop in venous pressures to relieve pulmonary congestion. A loop diuretic fits this goal best because it provides potent, fast diuresis and also causes venodilation, which lowers preload and helps decompress the pulmonary circulation. Furosemide acts by inhibiting the Na-K-2Cl transporter in the thick ascending limb of the loop of Henle, leading to large amounts of sodium and water being excreted. When given intravenously, its onset is rapid, making it ideal for acute pulmonary edema.

Mannitol is an osmotic diuretic that can be used for other indications (like reducing intracranial pressure) but is not the standard first-line choice for pulmonary edema because it can shift fluid into the intravascular space initially and is less predictable for rapid relief of edema. Acetazolamide, a carbonic anhydrase inhibitor, causes mild diuresis with slower onset and less impact on preload. Hydrochlorothiazide is a thiazide diuretic useful for chronic or mild edema but does not provide the rapid, potent effect needed in acute pulmonary edema.