Which medication decreases preload in acute pulmonary edema?

In acute pulmonary edema, the goal is to rapidly reduce the volume of fluid returning to the heart — that is, to decrease preload. Furosemide, a loop diuretic, accomplishes this through two complementary mechanisms: within minutes of IV administration it produces venodilation, which shifts blood volume peripherally and reduces venous return; over the subsequent 30–60 minutes it produces a robust diuresis that further decreases circulating volume and left ventricular filling pressures, relieving pulmonary congestion. Antibiotics have no hemodynamic effect and are used only when there is a concurrent infectious cause. Warfarin is an anticoagulant that prevents thrombus formation and has no effect on preload or volume status. Insulin is used to manage blood glucose and has no direct role in preload reduction. Students sometimes confuse medications that reduce afterload (such as nitroprusside or ACE inhibitors) with those that reduce preload; furosemide is the classic preload-reducing agent in pulmonary edema management. Its prompt use can dramatically improve symptoms and oxygenation in an acute episode.