Fluid Volume Deficit

Fluid volume deficit is a reduction in extracellular fluid, usually from inadequate intake, excessive loss, or movement of fluid into a space where it cannot support circulation. The immediate nursing question is not simply, “Does this patient look dry?” It is, “Is circulating volume low enough to impair tissue perfusion, and is the deficit still progressing?” A patient with several days of diarrhoea may have thirst, dry mucous membranes, tachycardia, concentrated urine, and orthostatic symptoms before blood pressure falls. Another patient may have a normal blood pressure but worsening confusion and almost no urine output. Those changes carry more urgency than the appearance of the skin alone. The priority is to identify deteriorating perfusion, determine whether oral replacement is safe, replace volume appropriately, and find the cause of the loss.