Method and device for monitoring a fluid system of an extracorporeal blood treatment device

An apparatus for monitoring a fluid system of an extracorporeal blood treatment apparatus, the extracorporeal blood treatment apparatus comprising:

• a dialyser or filter subdivided into a first chamber and a second chamber by a semipermeable membrane, an extracorporeal blood circuit having an arterial blood line leading to the first chamber and a venous blood line leading away from the first chamber, a venous drip chamber arranged in the venous blood line downstream of the first chamber, a venous locking organ arranged in the venous blood line downstream of the venous drip chamber, a blood pump arranged in the extracorporeal blood circuit, a ventilation line branching off from the venous drip chamber, and at least one hydrophobic filter arranged in said ventilation line that can be closed off by a ventilation valve arranged in a section of the ventilation line remote from the venous drip chamber, wherein the apparatus for monitoring the fluid system comprises:
• a measuring unit configured to measure the pressure in the ventilation line in the section of the ventilation line remote from the venous drip chamber;
• and
• a control and computational unit configured to evaluate the measured pressure signal and to determine there is a fault if pressure variations of the pressure signal are absent, wherein the control and computational unit is also configured to alternately at least partly open and close the venous locking organ whereby the fluid level in the venous drip chamber alternately rises and falls, as a result of which the measured pressure signal is subject to periodic pressure variations if there is no fault.

An extracorporeal blood treatment apparatus comprising:

• a dialyser or filter subdivided into a first chamber and a second chamber by a semipermeable membrane;
• an extracorporeal blood circuit having an arterial blood line leading to a first chamber and a venous blood line leading away from the first chamber;
• a venous drip chamber arranged in the venous blood line downstream of the first chamber;
• a venous locking organ arranged in the venous blood line downstream of the venous drip chamber;
• a blood pump arranged in the extracorporeal blood circuit;
• a ventilation line branching off from the venous drip chamber;
• at least one hydrophobic filter arranged in said ventilation line that can be closed off by a ventilation valve arranged in a section of the ventilation line remote from the venous drip chamber;
• and
• an apparatus for monitoring the fluid system of the extracorporeal blood treatment apparatus comprising:
• a measuring unit configured to measure the pressure in the ventilation line in the section of the ventilation line remote from the venous drip chamber;
• and
• a control and computational unit configured to evaluate the measured pressure signal and to determine there is a fault if pressure variations of the pressure signal are absent, wherein the control and computational unit is also configured to alternately at least partly open and close the venous locking organ whereby the fluid level in the venous drip chamber alternately rises and falls, as a result of which the measured pressure signal is subject to periodic pressure variations if there is no fault.