(EN) Device for determining the blood volume and/or blood volumetric flow of a circulation section, with- a fluid storage unit (2) for storing a measuring fluid (3),- an injection means, especially a catheter (11) or a cannula, for injecting the measuring fluid (3) into the circulatory system,- at least one pump device (5). arranged between the fluid storage unit (2) and the injectionmeans,- means for determining at least one property of the measuring fluid (3) prior to the injection intothe circulatory system,- means for determining the respective property in the circulatory system downstream from theinjection site, and- an analysis device for calculating the blood volume or volumetric flow as a function of theproperties determined,characterized in thatthe measuring fluid (3) can be taken from the fluid storage unit (2) by means of a first pumpdevice (5) to a second pump device (9) and from the second pump device (9) to the bloodcirculation.
