Physiology of Body Fluid Compartments and Body Fluid Movements

Management of Fluid Overload in the Pediatric ICU

“…The transcellular space refers to digestive, cerebrospinal, intraocular, pleural, peritoneal, and synovial fluids [3]. The movement of water between the three compartments of the extracellular space occurs through a semipermeable membrane [4].…”

“…The homeostatic state of fluid movement within the body is determined by a balance between the physical properties between the fluids that exist within each individual compartment and the properties of the semipermeable membranes that separate them, as detailed in Table 11.1 [4]. Fluid movement is further tightly regulated by feedback loops involving the central nervous, endocrine, and renal systems [2].…”

“…11 As fluid moves throughout the length of the capillary bed toward the venule end, filtration will eventually lead to a comparatively increased concentration of proteins within the intravascular space and thus an increased intravascular oncotic pressure in comparison to the interstitial fluid. This differential in oncotic pressure at the venule end of the capillary is greater than the hydrostatic differential, and so there is reversal of flow based on an overall pressure gradient that leads to absorption of fluid back into the intravascular space [4]. This process is summarized in Fig.…”