PREDICTION OF REACTIVE HYPEREMIA IN VASCULAR PATHOLOGIES USING ELASTIC POROUS TUBE MODEL

A mathematical model of reactive hyperaemia has been developed, in whi ch the limb vascular system is represented by an elastic porous tube, with flow in the tube equivalent to blood flow in the arteries and lar ge arterioles. Flow through the porous walls represents flow into the small arterioles, which respond actively by contracting as pressure th roughout the system rises following occlusion release. A variety of va scular pathologies have been simulated; the effect of venous packing o f the limb is to reduce the transient peak flow from normal, owing to a reduction in the pressure gradient. Occlusive disease of the femoral artery and lower arterial vessels reduces the magnitude and extends t he duration of hyperaemic flow, due to a reduced pressure gradient and increased resistance. Small vessel disease reduces the hyperaemic flo w, principally due to a reduction in the initial dilation of the vesse ls. Venous disease does not affect the initial arterial flow following occlusion release but reduces the equilibrium flow. The venous outflo w increases in response to an increase in the arterio-venous pressure gradient.