Fig. 2

New fluid filtration model. This model proposes that the glycocalyx, which is composed of a glycoprotein skeleton and proteoglycans, interacts with circulating cells and plasma constituents (including albumin) to form an endothelial surface up to 1 μm thick. The interstitial space is considered to have a high protein concentration (Ptn) and, thus, a high oncotic interstitial pressure (Oip), which decreases fluid return to the plasma compartment. Additionally, due to the retention of human albumin molecules in the glycocalyx layer, this structure may generate its own oncotic pressure (Osg), which further jeopardizes fluid return to the plasma compartment. The residual fluid volume in the IS in this model is much greater than in the classic Starling model, and excess fluid may return through the lymph vessels