Mechanism of Edema
The generation of interstitial fluid is described by Starling equation , which states the relationship between osmotic pressure and hydrostatic pressure , agents with opposite directions along the walls of semi-permeable of the capillaries .
The hydrostatic pressure in the healthy organism, which tends to determine the leakage from the capillaries, it is almost balanced by the osmotic pressure colloid, which is exercised in the opposite direction.
The minimum leakage into the interstitial space is drained by lymphatic vessels, which put back in the venous circulation via the thoracic duct that empties into the junction between the subclavian and internal jugular vein.
When the hydrostatic pressure is no longer balanced by the pressure-colloid osmotic lymphatic obstruction occurs, increases vascular permeability and there is an accumulation of fluid in the interstices, which, if unresolved, causes edema.