Fig. 1
Theoretical prediction of capillary hydrostatic pressure as a function of ratio of hydraulic resistance in arterioles to venules. Capillary hydrostatic pressure (P C) was obtained from the equation in the box on P C (i.e., the Pappenheimer-Soto Rivera equation). The equation is determined by hydrostatic pressures in the arteriole (P A) and venule (P V) and the ratio of hydraulic resistance of the arteriole (R A) to that of the venule (R V) (i.e., R A/R V) assuming that blood flow is constant through the capillary (arrow in the figure in the box). Increased P A (without change of P V) or increased P V (without change of P A) increases P C compared to the normal state. Vasodilation increases P C (i.e., leftward in the P C curve), while vasoconstriction decreases P C (i.e., rightward in the P C curve). P C varies in a rather complicated fashion in the clinical setting due to different changing patterns of P A, P V, and R A/R V. The pressure values of P A and P V are expressed in mmHg. Shaded area denotes the normal value of R A/R V