Extracorporeal blood treatment device and method for monitoring the integrity of a dialyzer of an extracorporeal blood treatment device

An extracorporeal blood treatment device for carrying out an extracorporeal blood treatment, in which blood flows in an extracorporeal blood circuit through a blood chamber of a dialyser that is separated by a semi-permeable membrane into the blood chamber and a dialysate chamber, the dialysate chamber comprising an inlet and an outlet, the extracorporeal blood treatment device comprising:

• the dialyser,
• a fluid system comprising at least the dialysate chamber of the dialyser, a dialysate supply line connected to the inlet, and a dialysate discharge line connected to the outlet,
• a pump system for filling the fluid system, including the dialysate chamber, with a liquid, and for establishing a pressure difference between the blood chamber and the dialysate chamber, the pump system comprising a blood pump and at least one pump for filling the fluid system,
• a pressure measuring apparatus, comprising one or more pressure sensors, for measuring pressure in the fluid system, including in the dialysate chamber, for carrying out an integrity test for monitoring integrity of the dialyser, and
• a control and arithmetic unit that cooperates with the pump system and the pressure measuring apparatus and that provides a preparation mode in preparation for the extracorporeal blood treatment, wherein
• for carrying out the preparation mode, the control and arithmetic unit is configured such that:
• the fluid system, including the dialysate chamber, is filled with the liquid,
• the integrity test for monitoring the integrity of the dialyser is carried out after the fluid system, including the dialysate chamber, has been filled with the liquid,
• the blood chamber is filled with a liquid after the integrity test has been carried out, the integrity test is carried out by the control and arithmetic unit in the preparation mode such that a pressure difference is established between the blood chamber and the dialysate chamber in such a manner that the pressure in the blood chamber is greater than the pressure in the dialysate chamber,
• an increase in pressure p, measured by the pressure measuring apparatus, in a given time interval, is determined, by the control and arithmetic unit,
• a leakage rate LR is determined, by the control and arithmetic unit, from the measured increase in the pressure p in the given time interval, and from a compliance C of the fluid system including the dialysate chamber, C being determined by the control and arithmetic unit, and
• a lack of integrity of the dialyser is concluded, by the control and arithmetic unit, on the basis of the leakage rate LR, and wherein
• the control and arithmetic unit generates an intervention control signal upon concluding the lack of integrity of the dialyzer, and cooperates with the pump system, based on the intervention control signal, to carry out an intervention whereby operation of the extracorporeal blood treatment device in the treatment mode is prevented.