Network Analysis Of The Microcirculation

Abstract

Network hemodynamic models of the microcirculation were formulated on the basis of a phenomenological relationship between pressure and flow for each individual vessel and specific geometries for capillary vessel connectivity. These relationships were implemented with a computer program developed for this purpose using Guassian Elimination with scaled partial pivoting. The resulting system was then analyzed to determine the flow through each vessel and the pressure at each vessel branch point under control conditions. These resistances were then altered from the control values to an increase or decrease of fifty percent from the control values. These analyses demonstrate (1) the significant variability between capillary vessel flows and pressures depending on the vessel's position in the network and (2) the sensitivity of flow and pressure inindividual vessels to resistance alteration in the other vessels of the system. Furthermore, limitations in the concpet of additivity of the resistances at each level in branching systems is demonstrated. These observarions have important implications with respect to overall understanding of microcirculatory performance and control and with respect to experimental approaches in which flow and pressure parameters of numerous individual vessels are studied without identification of the vessel's relationship to the network in which it lies.