Twenty-one Reasons Affirming Starling’s Law on the Capillary-interstitial Fluid Transfer Wrong and the Correct Replacement is the Hydrodynamic of the Porous Orifice (G) Tube

Abstract

Many reasons why Starling’s law wrong and the correct replacement is the hydrodynamic of porous orifice (G) tube exist. Starling’s hypothesis is based on Poiseuille’s work in which the hydrostatic pressure causes filtration. The oncotic pressure force of plasma proteins causes re-absorption. Starling’s law is wrong on both forces. The capillary has a pre-capillary sphincter and pores that allow the passage of plasma proteins. This makes the capillary a porous orifice (G) tube with different hydrodynamic; side pressure causes suction not filtration. The pores nullify the oncotic force in vivo. There is evidence to show that the osmotic chemical composition of various body fluids is identical to plasma proteins. The interstitial fluid (ISF) space has a negative pressure of -7 cm water. Evidence on Albumin versus Saline for fluid resuscitation shows no significant difference. This affirms that the oncotic force does not exist in vivo that partly prove Starling’s law wrong. Inadequacy in explaining the capillary–ISF transfer, has previously called for reconsideration of Starling’s hypothesis. Physics and physiological research demonstrate that pressure does not cause filtration across the wall of G tube, it causes suction. In G tube negative side pressure gradient causing suction maximum near the inlet and turns positive maximum near the exit causing filtration. Physiological study completed the evidence that Starling’s law is wrong as the capillary works as G tube not Poiseuille’s tube. Both absorption and filtration are autonomous functions of G tube thus fit to replace Starling’s law. The clinical significance is discussed.