ECFVE, or extracellular fluid volume excess, occurs when there is increased retention of sodium and water in the intravascular and interstitial spaces. This most commonly results from renal or heart disorders that impair sodium regulation. Symptoms include dyspnea, edema, neck vein engorgement, and crackles in the lungs. Treatment involves diuretics and a low-sodium diet to promote sodium and water excretion and reduce fluid overload. Patients must be carefully monitored for changes in vital signs, edema, and lab values to ensure fluid balance is restored.