A compartmental model of human microvascular exchange

To study the distribution and transfer of fluid and albumin between the human circulation, interstitium and lymphatics, a dynamic mathematical model is formulated. In this model, the human microvascular exchange system is subdivided into two distinct compartments: the circulation and the interstitium. Fluid is transported from the capillary to the interstitium by filtration according to the Starling’s hypothesis, while albumin is transported passively by coupled diffusion and convection through the same channels that carry the fluid. Data for parameter estimation are taken from a number of studies involving human microvascular exchange and include information from normals, nephrotics, heart failure patients, and also information from experiments on both normals and patients following saline or albumin solution infusions. Transport parameters are determined by fitting model predicted results to available measurements from the literature. The best-fit parameters obtained are LS = 43.08 ± 4.62 mL• mmHg⁻¹•h⁻¹, õ = 0.9888 ± 0.002, Pc,0 = 11.00 ± 0.03 mmHg, PS = 73.01 mL•h⁻¹, KF = 121.05 mL•mmHg⁻¹•h⁻¹, and JL,O = 75.74 mL•h⁻¹. Simulation of the available experimental data using these parameters gave a reasonable fit in terms of both trends and absolute values. All of the best-fit parameter values are in reasonable agreement with estimated values based on experimental measurements where comparisons with literature data are possible. The fully described model is used to simulate the transient behaviour of the system when subjected to an intravenous infusion of albumin and the predicted values compare reasonably well with the experimental infusion data of Koomans et al. (1985). The coupled Starling model is able to successfully simulate the transport mechanisms of human microvascular exchange system.Applied Science, Faculty ofChemical and Biological Engineering, Department ofGraduat