In acute CHF with pulmonary edema, which therapy primarily reduces preload?

• A. Nitro
• B. Furosemide
• C. Morphine
• D. Dopamine

Answer: (A)

Reducing preload quickly to lower left-sided filling pressures is the goal in acute pulmonary edema. Nitroglycerin does this mainly by venodilation, which increases venous capacitance and decreases venous return to the heart. That drop in venous return lowers the left ventricular end-diastolic pressure and the pulmonary capillary wedge pressure, easing pulmonary congestion and improving oxygenation and symptoms rapidly.

Furosemide reduces preload by diuresis, but its effect is slower and depends on renal function and fluid shifts. Morphine can cause venodilation as well but isn’t used primarily for preload reduction due to limited benefit and potential respiratory risks. Dopamine doesn’t primarily decrease preload and can have other hemodynamic effects.