Abstract: A method for determining a pressure of a medical fluid in a fluid line by using at least one centrifugal pump includes detecting the pressure upstream of the centrifugal pump while considering an information about a pressure downstream of the centrifugal pump, or detecting the pressure downstream of the centrifugal pump while considering an information about a pressure upstream of the centrifugal pump. Thereby, at least one information about the volume flow in the fluid line and/or at least one information about a rotation speed of the centrifugal pump are considered, respectively. The invention also relates to a method for determining a volume flow, an arithmetic unit, a treatment apparatus, a digital storage means, a computer program product and a computer program.

Abstract: The present invention relates to a method for determining at least a first volume flow in a blood treatment apparatus which comprises: a primary circuit for conducting the blood to be treated; a secondary circuit for conducting a fluid that is used for the blood treatment; a blood treatment module provided for exchanging fluids and/or substances between the primary circuit and the secondary circuit; and an optionally provided fluid connection between the primary circuit and the secondary circuit, provided for introducing the first volume flow from the secondary circuit into the primary circuit; wherein the method encompasses determining the first volume flow of the secondary circuit taking into account a first pressure value or pressure measurement and a second pressure value or pressure measurement in the secondary circuit. The present invention further relates to a calculating device and a blood treatment apparatus.