Method for regulating the supply of substituate during extracorporeal blood treatment and extracorporeal blood treatment device comprising a unit for regulating the supply of substituate

A method for controlling a rate of dosing substituate into an extracorporeal blood circuit during a hemodiafiltration treatment with an apparatus, the apparatus comprising the extracorporeal blood circuit, a blood pump, a dialyzing fluid system, a dialyzer divided by a semipermeable membrane into a blood chamber and a dialyzing fluid chamber, a sensor system, a substituate dose rate controller, and a control unit, wherein

• the semipermeable membrane comprises dialyzer fibers,
• the blood chamber is part of the extracorporeal blood circuit,
• the dialyzing fluid chamber being is of the dialyzing fluid system,
• the sensor system is configured for measuring transmembrane pressure (TMP) to determine a measured TMP value, and configured for measuring longitudinal flow resistance along the dialyzer fibers to determine a measured flow resistance value,
• the substituate dose rate controller is configured to increase or decrease a rate of dosing substituate to the extracorporeal blood circuit,
• the control unit is in communication with the sensor system and the substituate dose rate controller,
• and the method comprises:
• measuring transmembrane pressure (TMP);
• determining a measured TMP value;
• measuring longitudinal flow resistance along the dialyzer fibers;
• determining a measured flow resistance value;
• determining, with the control unit, an adjustment to a rate of dosing substituate into the extracorporeal blood circuit, based on both the determined measured TMP value and the determined measured flow resistance value;
• and
• adjusting the rate of dosing substituate into the extracorporeal blood circuit based on the determined adjustment.