Abstract: The invention relates to a method and device for determining the flow in a blood vessel, comprising the determining the relation between the shear rate and the impedance of flowing blood, measuring the impedance in the blood in a cross-section of the blood vessel, determining the shear rate from this relation and the measured impedance, determining the size of the cross-section of the blood vessel, selecting a theoretical relative flow distribution over the blood vessel cross-section, determining the average flow speed on the basis of the average shear rate and the relative flow distribution, and determining the flow volume from the determined average flow speed and the cross-section.

Abstract: The invention relates to a method for determining properties of blood, such as the blood viscosity of a person, comprising of generating in vivo for a determined time, by means of an electrical alternating current of a determined frequency, a measurement signal of the impedance of the blood between at least two points centrally in a blood volume, wherein the measurement signal is processed such that variations therein with a frequency in the order of magnitude of the heart frequency are substantially absent therefrom, and comparing the processed measurement signal with predetermined relations between impedance and the properties of the blood, such as the viscosity.