An apparatus for extracorporeal treatment of blood comprising a treatment unit, a blood withdrawal line, a blood return line, a preparation line and a spent dialysate line; a non-invasive blood volume sensor for determining an additional property of blood is active on a tube segment of the blood withdrawal line or of the blood return line; the sensor includes one source for directing a signal towards the blood, a plurality of detectors for receiving the signal, and a controller receiving the output signals from the detectors and determining a blood volume variation and a value of sodium concentration in the blood (Na.sub.Pl) both based on the output signals. A process of determining at least one parameter and on property of blood circulating an extracorporeal blood circuit is also disclosed.

This invention relates generally to magnetic sensors and related systems and methods. In some aspects of the invention, a magnetic sensor assembly includes a housing configured to releasably hold a medical fluid tube and a sensor secured to the housing, the sensor configured to detect a change in a strength of a magnetic field when a medical fluid passes through the medical fluid tube.

A medical device system including a physiological sensor and ultrafiltration unit senses a physiological signal in a patient and computes a fluid status measurement of the patient using the physiological signal. Ultrafiltration therapy is delivered to the patient according to a therapy delivery control parameter established in response to the fluid status measurement.

The present invention relates to a flow sensor for measuring a flow difference having at least two measurement chambers through which fluid is conductible; at least one means for producing a magnetic field for charge separation in a fluid flowing through the at least two measurement chambers; and at least one means for measuring an electric potential in the fluid flowing through the at least two measurement chambers, with the at least two measurement chambers being arranged such that they are run through by the same magnetic field line of the magnetic field for charge separation.