Overview
Introduction
Fluid volume imbalance is defined by the relationship between total body water and effective circulating volume.
Fluid volume imbalance is defined by the relationship between total body water and effective circulating volume. Losses that exceed intake reduce plasma volume and impair preload; sodium and water retention expand extracellular fluid and can congest the lungs. A third-space shift creates the deceptive middle picture: total body fluid may be high, yet vascular filling is poor. The bedside questions are therefore: Is perfusion adequate, and where is the fluid? Weight trends, orthostatic vital signs, lung sounds, mentation, urine output, serum electrolytes, and the clinical context answer those questions more reliably than edema alone.