Diuretics

A diuretic changes sodium handling in the nephron, and water follows sodium. That simple mechanism can relieve pulmonary congestion, reduce peripheral edema, or lower blood pressure. The same mechanism can also produce intravascular depletion, electrolyte-driven dysrhythmia, acute kidney injury, or medication toxicity. Before giving or escalating a diuretic, identify the problem being treated. A patient with crackles, orthopnea, raised jugular venous pressure, and rapid weight gain needs decongestion; a patient with dry mucous membranes, orthostatic symptoms, falling urine output, and rising creatinine may be harmed by more diuresis. Urine volume alone does not settle the question. It must be interpreted beside perfusion, weight, respiratory findings, blood pressure, renal function, and electrolytes. The experienced nurse looks first for the trend that changes priority: increasing oxygen requirement, a new blood-pressure drop, reduced urine output, altered mentation, or a rapid change in potassium or sodium. The medication name then explains what risk to anticipate and what response to expect.