Effective circulating volume

Effective Circulating Volume (ECV) is the volume of arterial blood (vascular extracellular fluid) effectively perfusing tissue. ECV is dynamic and not a measurable, distinct compartment. ECV is about 0.7 L in a 70 kg individual. This concept is useful for discussion of cardiovascular and renal physiology.

Additional recommended knowledge

Essential Laboratory Skills Guide

Weighing the right way

Correct Test Weight Handling Guide: 12 Practical Tips

Though E.C.V normally varies with extracellular fluid, it is uncoupled in diseases, such as congestive heart failure (CHF) or hepatic cirrhosis. Here decreased ECV may lead to volume-depletion responses and edema.

Decreased ECV can stimulate renin secretion or stimulate a sympatheic nervous system response or prostaglandin release (all of which help mediate renal blood flow and glomerular filtration rate among other things).

Reference: John Bullock, Michael B. Wang, Joseph Boyle. NMS Physiology. 4th ed., Lippincott Williams & Wilkins, 2001. pp 337-339.