Abstract:
The present invention relates to a method and a device for monitoring a flowing medium, in particular the blood flowing in an extracorporeal blood circulation, for the presence of air, in particular micro-bubbles. A sequence of signal pulses or a continuous signal is injected into the flowing medium, and the signal pulses or continuous signal leaving the flowing medium are received. To detect micro-bubbles, a signal pattern that is characteristic of the variation over time of the received signal pulses or the continuous signal in a predetermined period of time is extracted from the signal received. The characteristic signal pattern is compared with one or more characteristic reference patterns, and the presence of air bubbles is determined if the characteristic signal pattern deviates from the characteristic reference pattern by a predetermined amount. Statistical characteristic variables, in particular the variance, are preferably determined from the signal patterns and compared with one another.
Abstract:
In order to detect a leakage in a fluid system of a blood treatment apparatus having an extracorporeal blood circuit, the pressure in the fluid system is measured continuously during a predetermined period of the duration of treatment, and the leak rates are calculated from the change in the pressure at predetermined time intervals of the predetermined period of the duration of treatment. The leakage volume in the predetermined period of the duration of treatment is calculated from the leak rates, and the leakage volume is compared with a predetermined limit value. If the leakage volume is greater than the limit value, this indicates a possible loss of leaktightness in the system. This can be verified with a conventional pressure-holding test. The method and device are characterized by the fact that it is not necessary in principle to interrupt the blood treatment in order to detect a loss of leaktightness.
Abstract:
To monitor the functionality of a partial device of a blood treatment machine, an excess pressure is built up on the blood side and on the dialysis fluid side and is monitored to detect a pressure drop. To do so, the flow path through the dialysis fluid inlet line (12), the dialysis fluid outlet line (13) and the blood outlet line (6) can be interrupted, and the blood pump (7) is started. The test pressure on the dialysis fluid side is built up due to the ultrafiltrate passing through the membrane (2) of the dialyzer (1). Any leakage in the closed volume, which includes a part of the blood path as well as part of the dialysis fluid path, is then detected by a (greater) pressure drop.