Which describes the pharmacologic action of furosemide (Lasix) when used in pulmonary edema?

Which describes the pharmacologic action of furosemide (Lasix) when used in pulmonary edema?

• A. It causes vasodilation to increase venous capacitance and decrease preload.
• B. It causes vasoconstriction to decrease venous capacitance and improve preload.
• C. It decreases water retention by the adrenal glands to improve circulation.
• D. It increases water retention by the kidney to improve circulation.

Answer: (A)

In pulmonary edema, the fastest way to relieve edema is by lowering the amount of blood returning to the heart and the pressure in the pulmonary circulation. Furosemide acts as a loop diuretic, but it also has a rapid venodilatory effect that increases venous capacitance. This quick vasodilation lowers the preload—reducing left atrial and left ventricular filling pressures—and consequently decreases the hydrostatic pressure pushing fluid into the lungs. Over time, its diuretic action promotes loss of sodium and water by the kidneys, further reducing intravascular volume and edema. This combination of rapid venodilation with subsequent diuresis makes the described action the best fit for managing pulmonary edema. The other options describe actions that don’t match furosemide’s effects (it doesn’t cause adrenal-mediated water retention or vasoconstriction to improve preload).

In pulmonary edema, the fastest way to relieve edema is by lowering the amount of blood returning to the heart and the pressure in the pulmonary circulation. Furosemide acts as a loop diuretic, but it also has a rapid venodilatory effect that increases venous capacitance. This quick vasodilation lowers the preload—reducing left atrial and left ventricular filling pressures—and consequently decreases the hydrostatic pressure pushing fluid into the lungs. Over time, its diuretic action promotes loss of sodium and water by the kidneys, further reducing intravascular volume and edema. This combination of rapid venodilation with subsequent diuresis makes the described action the best fit for managing pulmonary edema. The other options describe actions that don’t match furosemide’s effects (it doesn’t cause adrenal-mediated water retention or vasoconstriction to improve preload).