Device for extracorporeal blood treatment having an evaluation and control unit

A blood treatment device comprising:

• an extracorporeal blood circuit, which includes an arterial line, a blood pump, a blood treatment unit, and a venous line, the arterial and venous lines being connectable to a blood vessel of a patient, and
• an evaluation and control unit,
• the evaluation and control unit being configured to carry out the following steps:
• (a1) determining a blood recirculation in a blood vessel of the patient connected to the extracorporeal blood circuit;
• (b) calculating a blood flow in the blood vessel using the blood recirculation determined in accordance with (a1) and using a provided value or a value likewise previously determined for a cardiac output of the patient;
• and
• accounting for an extracorporeal blood flow and an outflow of fluid in the blood treatment device, in addition to the blood recirculation and the cardiac output, when determining the blood flow in step (b) for controlling operation of the blood treatment device.