Detection of a disruption of a fluid connection between two fluid containing systems

A monitoring system for detecting a disruption of a fluid connection between a first fluid containing system and a second fluid containing system, the monitoring system comprising:

• a first signal generating arrangement including a first signal filter for generating a monitoring signal which is representative of a fluid pressure in respect of the first fluid containing system and which is responsive to the disruption of the fluid connection;
• a detector for detecting a condition indicative of the disruption by comparing a current pressure value of the monitoring signal to a detection range;
• a second signal generating arrangement including a second signal filter for generating a tracking signal which corresponds to and is more smoothed over time than the monitoring signal;
• and
• a signal range generator for setting the detection range in a given relation to the tracking signal so that the detection range follows changes in the tracking signal,
• wherein at least one of the first and second signal filters comprises a moving average filter which is configured to generate a time-sequence of filtered values based on signal values in an input signal, wherein each filtered value is computed as an average of the signal values within a time window in the input signal, the moving average filter being configured to, based on a reference signal indicative of a current operating frequency of a repetitive pulse generator in the first or second fluid containing system, set the length of the time window to effectively match a given whole number of pulsations generated by the repetitive pulse generator.

A method of detecting a disruption of a fluid connection between a first fluid containing system and a second fluid containing system, the method comprising:

• generating, via a first signal filter, a monitoring signal which is representative of a fluid pressure in respect of the first fluid containing system and is responsive to the disruption of the fluid connection;
• detecting a condition indicative of the disruption by comparing a current pressure value of the monitoring signal to a detection range;
• generating, via a second signal filter, a tracking signal which corresponds to and is more smoothed over time than the monitoring signal;
• and
• setting the detection range in a given relation to the tracking signal so that the detection range follows changes in the tracking signal,
• wherein the first and second signal filters define a respective lowest frequency passband extending between lower and upper limit frequencies, wherein the upper limit frequency of the second signal filter is lower in frequency than the upper limit frequency of the first signal filter.

A monitoring system comprising:

• a signal generating arrangement configured to generate, via a first signal filter, a monitoring signal which is representative of a fluid pressure in respect of an extracorporeal blood circuit, the extracorporeal blood circuit having first and second ends for connection in fluid communication with the vascular system of a patient and comprising a blood pump for circulating blood from the first end through a blood processing device to the second end, the monitoring signal being generated to be responsive to a disconnection of the extracorporeal blood circuit from the vascular system of the patient downstream of the blood pump;
• and
• a disconnection detector configured to detect a condition indicative of the disconnection by comparing a current pressure value of the monitoring signal to a detection range,
• wherein the signal generating arrangement is configured to generate, via a second signal filter, a tracking signal which corresponds to and is more smoothed over time than the monitoring signal,
• wherein the first and second signal filters define a respective lowest frequency passband extending between lower and upper limit frequencies, wherein the upper limit frequency of the second signal filter is lower in frequency than the upper limit frequency of the first signal filter, and
• wherein the disconnection detector is configured to set the detection range in a given relation to the tracking signal so that the detection range follows changes in the tracking signal.

An apparatus for extracorporeal blood processing comprising:

• an extracorporeal blood circuit for connection in fluid communication with the vascular system of a patient at first and second ends and comprising a blood pump for circulating blood from the first end through a blood processing device to the second end;
• a signal generating arrangement configured to generate, via a first signal filter, a monitoring signal which is representative of a fluid pressure in respect of the extracorporeal blood circuit and which is responsive to a disconnection of the extracorporeal blood circuit from the vascular system of the patient downstream of the blood pump;
• and
• a disconnection detector configured to detect a condition indicative of the disconnection by comparing a current pressure value of the monitoring signal to a detection range,
• wherein the signal generating arrangement is configured to generate, via a second signal filter, a tracking signal which corresponds to and is more smoothed over time than the monitoring signal,
• wherein at least one of the first and second signal filters comprises a moving average filter which is configured to generate a time-sequence of filtered values based on signal values in an input signal, wherein each filtered value is computed as an average of the signal values within a time window in the input signal, the moving average filter being configured to, based on a reference signal indicative of a current operating frequency of a repetitive pulse generator in the first or second fluid containing system, set the length of the time window to effectively match a given whole number of pulsations generated by the repetitive pulse generator, and
• wherein the disconnection detector is configured to set the detection range in a given relation to the tracking signal so that the detection range follows changes in the tracking signal.

A method of detecting a disruption of a fluid connection between a first fluid containing system and a second fluid containing system, the method comprising:

• generating, via a first signal filter, a monitoring signal which is representative of a fluid pressure in respect of the first fluid containing system and is responsive to the disruption of the fluid connection;
• detecting a condition indicative of the disruption by comparing a current pressure value of the monitoring signal to a detection range;
• generating, via a second signal filter, a tracking signal which corresponds to and is more smoothed over time than the monitoring signal;
• and
• setting the detection range in a given relation to the tracking signal so that the detection range follows changes in the tracking signal,
• wherein at least one of the first and second signal filters comprises a moving average filter which is configured to generate a time-sequence of filtered values based on signal values in an input signal, wherein each filtered value is computed as an average of the signal values within a time window in the input signal, the moving average filter being configured to, based on a reference signal indicative of a current operating frequency of a repetitive pulse generator in the first or second fluid containing system, set the length of the time window to effectively match a given whole number of pulsations generated by the repetitive pulse generator.