Vascular access and fluid management
We tend to forget that we humans (and many of our animal relatives) are mostly water. When we think about it, we must marvel how the body stores the bulk of this water in cells and the interstitial, extracellular fluid, where much of the water is tied up in gel. Suspended in this interstitial lake is the vascular compartment, comparatively puny in volume but most important because of its rapid transport of fluids, nutrients, and waste throughout the system, and its continuous and efficient exchange of water with the interstitial compartment (Fig. 3.1). Clinically, we can see dehydration in sunken eyeballs, wrinkling skin and dry lips, or the excess of fluids in edema and swollen eyes; we can even hear it should water collect in the alveoli.