Volemia

Volemia refers to the volume status of the body’s fluids, particularly the intravascular compartment that contains circulating blood plasma. Clinically, volemia is categorized as euvolemia (normal volume), hypovolemia (reduced circulating volume), or hypervolemia (excess circulating volume). The balance depends on intake and losses of water and electrolytes, as well as shifts between compartments.

Hypovolemia commonly results from dehydration, gastrointestinal losses, hemorrhage, or excess diuresis, and it can lead to reduced tissue perfusion and organ dysfunction. Hypervolemia arises with heart, liver, or kidney dysfunction, aggressive fluid administration, or conditions promoting fluid retention and edema. Redistribution or third-spacing of fluids can also alter effective circulating volume without a net gain or loss of total body water.

Assessment of volemia relies on history, examination, and monitoring. Signs of hypovolemia include tachycardia, hypotension, reduced skin turgor, and orthostatic changes; hypervolemia may present with edema, jugular venous distension, or pulmonary congestion. Laboratory testing and urine output help evaluate perfusion and renal function. Imaging and dynamic hemodynamic measures, such as ultrasound assessment of the inferior vena cava or other venous indices, can aid in estimating intravascular volume, alongside invasive monitoring when indicated.

Management is volume-status dependent. Hypovolemia is treated with fluid resuscitation using isotonic crystalloids or blood products as appropriate, while hypervolemia is managed with fluid restriction, diuretics, and, in some cases, renal replacement therapy. Achieving and maintaining euvolemia is a central goal in many critical care and perioperative settings.