Apparatus for extracorporeal blood treatment

A process of setting transmembrane pressure between a first chamber and a second chamber of a treatment unit in an apparatus for extracorporeal blood treatment,

• the apparatus comprising:
• at least one blood removal line connected with an inlet port of the first chamber and predisposed to remove blood from a patient;
• at least one blood return line connected to an outlet port of the first chamber and predisposed to return treated blood to the patient;
• at least one infusion line for providing replacement fluid, the at least one infusion line connected to one of said at least one blood removal line and said at least one blood return line;
• and
• at least one fluid evacuation line connected to an outlet port of the second chamber configured to receive at least one fluid filtered across the semipermeable membrane;
• the treatment unit having the first chamber and the second chamber separated from one another by a semipermeable membrane, wherein a difference in pressures in the first chamber and the second chamber across the semipermeable membrane defines a transmembrane pressure;
• the process comprising a setting sequence that comprises:
• imposing a first increase in transmembrane pressure (δTMP1) on a first transmembrane pressure (TMP1) to reach a second transmembrane pressure (TMP2);
• determining a value of a control parameter (φ1) corresponding to the first increase in transmembrane pressure, wherein the control parameter is related to a variation between a replacement flow in the at least one infusion line at the first transmembrane pressure (TMP1) and a replacement flow in the at least one infusion line at the second transmembrane pressure (TMP2);
• comparing the value of the control parameter (φ1) corresponding to the first increase in transmembrane pressure (δTMP1) with a reference value (φref);
• determining if the value of the control parameter (φ1) corresponding to the first increase in transmembrane pressure (δTMP1) is greater than the reference value (φref);
• and
• if the value of the control parameter (φ1) corresponding to the first increase in transmembrane pressure (δTMP1) is greater than the reference value (φref), imposing a second increase (δTMP2) on the transmembrane pressure which is greater than the first increase in transmembrane pressure (δTMP1) to reach a third transmembrane pressure (TMP3).