System for monitoring the pressure in a blood line and a device to be used with such a system

[0001] The invention relates to the area of ​​devices for monitoring pressure in blood lines, see e.g. EP 1547630.

[0002] In extracorporeal blood processing, blood is taken from the patient's body, circulates in the extracorporeal blood circuit containing the blood processing unit, and is introduced back into the patient's body. Examples of such blood processing are procedures used for kidney damage, such as hemodialysis, hemofiltration, and hemodiafiltration. Examples of blood processing for failure or disease of other organs are oxygenation of blood, separation of blood components by centrifuges and filtration techniques, and removal of blood components by absorption.

[0003] During blood processing, blood circulates continuously or almost continuously in the blood lines of the extracorporeal blood system. To monitor conditions in the extracorporeal blood circuit, pressure is continuously measured in an arterial blood line from the patient's body to the blood processing unit and in a venous blood line from the blood processing unit to the patient's body. In modern devices, this is achieved due to pressure transducer lines branching off from the arterial blood and venous blood lines, respectively, and leading to the pressure transducers, which are part of the blood processing device.

[0004] In order to avoid soiling of the pressure transducers, and hence the blood processing device, a first pressure transducer protective filter is used, dividing the pressure transducer line into a bloodline section between the blood line and the filter and a pressure transducer section between the filter and the pressure transducer. Such contamination is not desirable from the point of view of possible transmission of the infection to the patient's blood, which is processed later in the same device. In addition, spilled blood can destroy the pressure sensor and associated electronics.

[0005] The pressure transducer protective filter may be permeable to gas, such as air, but not to liquid, such as blood. For this reason, it is preferred to use hydrophobic filter materials. In addition, the membrane element in the filter has pores, small enough to block the passage of matter, such as bacteria and germs, that could threaten sterile hygiene conditions on both sides of the filter when air passes through the filter.

[0006] The pressure transducer section is usually releasable by connecting means comprising a connector and a connector paired with it. After processing the blood, it is thus possible to replace and remove the extracorporeal blood line and parts of the pressure transducer line comprising the blood line section, the first pressure transducer protective filter and the pressure transducer section extending from the filter to the connection means. These parts can be made as a single set of blood lines. The rest of the pressure transducer line and the pressure transducer itself are part of the blood processing device and can be reused for the next patient. Since the first protective pressure transducer filter protects these parts from any contact with blood, there is no need to replace them after proper use. [0007] At the beginning of processing, a new blood line is mounted to the blood processing device and the blood transducer set pressure transducer lines are connected to the blood processing device by connecting means. When, before connecting the patient, the function of the extracorporeal blood circuit is checked by means of actuators, some air is trapped in the pressure transducer lines. Despite this, the air transfers pressure from the appropriate blood line to the pressure transducer. As the pressure rises, the air volume is compressed, but the line geometry is properly designed so that, under normal conditions, the blood level will not reach the first pressure transducer protective filter; otherwise the risk of the filter becoming blocked by the blood increases and that the pressure cannot be properly transmitted through the filter.

[0008] As long as the integrity of the first filter is not compromised, the blood cannot enter the pressure transducer section of the pressure transducer line and any infection is avoided. Because all parts of the blood line kit that come into contact with the blood are replaced with new and sterile parts, no new transmission of infection can occur prior to treating a new patient. However, the situation is different when the first pressure transducer protective filter breaks. In this case, blood may leak to the pressure transducer section through the torn filter. Current hemodialysis devices in the pressure transducer section therefore have a second protective pressure transducer filter. The second filter is located inside the hemodialysis device housing and divides the pressure transducer section into a first part between two filters and a second part between the second filter and the pressure transducer. The second filter is not part of the disposable blood line set and serves only as excess. When blood leakage occurs in the first pressure transducer protective filter, the second pressure transducer protective filter avoids any contamination and / or damage to parts after the second filter, in particular the pressure transducer.

[0009] This prior art system has the disadvantage that the rupture of the first filter can be unnoticed by the user of the blood processing device. Any blood that gets past the first filter can contaminate any part of the first part of the pressure transducer section. In addition, the membrane element of the second protective filter of the pressure transducer may be at least partially blocked by penetrating blood. Although the pressure transducer is still protected by a second filter, this filter can no longer properly transmit atmospheric pressure. Last but not least, if it goes unnoticed by the user, the blood remaining in the first part of the pressure transducer section will not be removed by replacing the disposable blood line set, which will cause a possible hygiene problem.

[0010] It is therefore an object of the present invention to provide a system that avoids the possibility of unnoticed damage to the first pressure transducer protective filter in the pressure transducer line. This problem is solved by the system according to claim 1. Preferred embodiments are subject to the dependent claims.

[0011] The invention provides a blood line pressure monitoring system, the system comprising a blood line, a pressure transducer line branching from the blood line and leading to a pressure transducer, measuring the pressure in the pressure transducer line, the first protective filter of the pressure transducer in the line pressure transducer divides the pressure transducer line into a bloodline section between the bloodline and the filter and a pressure transducer section between the filter and the pressure transducer, the first protective pressure transducer filter being permeable to gas, but not to the liquid, in which the system further includes a liquid detection sensor in the pressure transducer section of the pressure transducer line.

[0012] When the first pressure transducer protective filter bursts, the leaking liquid enters the pressure transducer section, where the leaking liquid will be detected by a sensor that is in this region of the pressure transducer line. In a preferred embodiment of the invention, the leaking liquid to be detected is blood or physiological fluid. Physiological fluid can be used as a fluid during startup for the blood line and as a kind of buffer between blood in the blood line and air trapped in the pressure transducer line to avoid any direct contact of blood with air. In this case, mostly physiological fluid will leak through the torn filter, not blood. Any other liquid intended for this purpose may well be used. The sensor must therefore be selected depending on the leaking liquid to be detected by the sensor. [0013] In a specific embodiment of the invention, the sensor is an optical sensor checking the optical transducer section, preferably the transparency of the pressure transducer section, selectively within two wavelengths.

[0014] In another embodiment of the invention, the sensor is an electric sensor checking the electrical properties in the pressure transducer section, in particular at least one of the following: conductivity, capacity, inductance.

[0015] In a further embodiment of the invention, the sensor is an ultrasonic sensor, comprising an ultrasonic transmitter and an ultrasonic transducer. With the help of an ultrasonic sensor, the detection time of the ultrasonic signals through the pressure transducer section can be used to detect the presence of any liquid in this line.

[0016] In another embodiment of the invention, the sensor is a first sensor for detecting a first liquid, wherein the system further comprises a second sensor for detecting the presence of a second liquid in the pressure transducer section of the pressure transducer line. The first sensor may be used to detect the leakage of the first liquid, such as blood, and the second sensor may be used to detect the leakage of the second liquid, such as the fluid used when starting the device, depending on the sensitivity of the sensors to the liquids to be detected. For example, an optical sensor can be used to detect a first fluid, such as blood, and an ultrasonic sensor to detect a second fluid, such as the fluid used to start the device. The next example can be two optical sensors that use two different optical wavelengths.

[0017] Depending on the coupling of the sensor or sensors to the pressure transducer section, either conventional dialysis systems or particularly shaped probe chambers such as cuvettes can be used.

[0018] In further embodiments of the invention, the system also includes a second pressure transducer filter dividing the pressure transducer section into the first part between the filters and the second part between the second filter and the pressure transducer, where the second protective pressure transducer filter is also gas permeable, but not for liquids and where the sensor detects the presence of liquid in the first part of the pressure transducer section.

[0019] The pressure transducer and the second protective pressure transducer filter can be attached to the housing. The first part of the pressure transducer section can be detachable using connecting means comprising a connector and a paired connector, dividing the pressure transducer section into a housing section leading to the second protective transducer filter and into a disposable section leading to the first protective pressure transducer filter where the sensor detects presence of liquid in the housing section of the first part of the pressure transducer section.

[0020] It is also an object of the invention to provide a device used in the system described above, which avoids unnoticed damage to the first pressure transducer protective filter in the pressure transducer line and where the device itself can easily be reused. This problem is solved by the device according to claim 15. Advantageous embodiments are subject to the dependent claims.

[0021] The device according to the invention comprises a housing part according to an embodiment of the system according to the invention, wherein the system consists of disposable parts and a housing part. The housing part includes a paired connector, a second protective pressure transducer filter, a sensor that detects the presence of liquid in the pressure transducer section, the housing section of the first part of the pressure transducer section between the paired connector and the protective pressure transducer filter, the second part of the pressure transducer section and the pressure transducer. By connecting the connector of the respective disposable part of the system according to the invention and the paired connector of such a device it is possible to detect any liquid leaking due to the rupture of the first protective filter of the pressure transducer. Furthermore, the device can easily be reused by disconnecting the disposable part from the device by means of connecting means. The disposable part can be safely removed after use and replaced with a new disposable part before the next procedure, e.g. a blood line set.

In a particularly preferred embodiment of the invention, the device is a blood processing device with a control unit for controlling and monitoring blood processing, the blood circulating in the extracorporeal blood circuit. In this case, the extracorporeal blood circuit further comprises one or more blood lines that branch off into the pressure transducer lines, whereby the pressure in the blood lines is determined by the control unit of the blood processing device by means of pressure transducers. For processing alone, extracorporeal blood circulates in the blood processing unit. Examples of such devices are hemodialysis, hemofiltration and hemodiafiltration devices, where the blood processing unit is a blood hemodializer and / or hemofilter.

[0023] In another embodiment of the invention, the sensor detecting the presence of liquid is connected to the control unit of the blood processing device, where the sensor emits a first signal to the control unit if no fluid has been detected, and a second signal to the control unit if fluid has been detected. If a second signal is received from the sensor, the control unit may emit an alarm signal.

[0024] Advantages of the inventive concept will become more apparent from an embodiment of the invention, which is described, for example, by means of figures. The figures show schematically at

Fig. 1 an embodiment of the system according to the invention, consisting of a reusable device according to the invention and disposable parts, and Fig. 2 a blood dialysis device with an extracorporeal blood circuit comprising two systems, shown in Fig. 1.

[0025] Fig. 1 shows an embodiment of a system 40 in accordance with the invention. It comprises a single-use part 10, which is part of a single-use blood line kit that can be replaced after each use, and a reusable device whose parts are not replaced after each use. The disposable portion 10 includes a blood line 11 from which the blood line section 12A of the pressure transducer line 12 branches off. These lines can be designed as a conventional set of dialysis lines. Alternatively, these lines can be made as any type of fluid conducting channel, in particular as cassette parts having rigid or flexible components. The pressure transducer line may branch off from the blood line directly or be implemented as part of a component like a trap of air carried by the blood. In fact, the only necessary condition is contact of pressure transducer line 12 with blood line 10 to allow pressure to be transmitted through pressure transducer line 12.

[0026] The pressure transducer line 12 is divided by the first pressure transducer protective filter 13 into the blood line section 12A between the blood line 11 and the first filter 13 and the pressure transducer section 12B between the first filter 13 and the pressure transducer 21. The pressure is measured by means of a pressure transducer 21, measuring the pressure in the pressure transducer line 12, and thus in the blood line 11. For example, the transducer may include a piezoelectric element that converts the force, and thus applied pressure to the electrical signal, as is known in the art.

[0027] The pressure transducer section 12B is then divided by the second pressure transducer protective filter 22 into the first part 12C between the two filters and the second part 12D between the second filter 22 and the pressure transducer 21 as shown in Fig. 1. The first part 12C is divided by connecting means 14 into a disposable section 12E and a housing section 12F. Connection means 14 includes a disposable connector 14A paired with the housing connector 14B. These connectors can be standard Luer latch connectors. The first and second protective filters 13 and 22 of the pressure transducer contain hydrophobic membrane elements 13A and 22A, permeable to gases like air, but not to fluids like blood or physiological fluid.

[0028] The disposable section 12E extends from the first pressure transducer protective filter 13 to the disposable switch 14A. The housing section 12F extends from the housing connector 14B to the second pressure transducer protective filter 22. In this embodiment of the system according to the invention, this solution allows easy replacement of the disposable part 10 by disconnecting the disposable connector 14A from the housing connector 14B and replacing the used disposable part 10 with a new and sterile one.

[0029] The reusable device 20 of the system 40 includes a housing 23 to which the housing section 12F, the second part 12D of the pressure transducer section 12B, a second pressure transducer protective filter 22 and the pressure transducer 21 together with connection lines 21a are attached. If the kit is sufficiently well attached to the housing, then it is not necessary to attach all components separately to the housing 23.

[0030] The sensor 24 with connecting leads 24a is located in the pressure transducer section 12B. This sensor is an optical sensor that measures the transparency of the pressure transducer section 12B at two respective wavelengths, or at least in two different light colors. The first wavelength is selected as reference and the second wavelength is specific for the presence of the detected fluid, e.g. blood. Such two-color sensors are already used to detect the presence of blood in other parts of blood processing devices and are known to those skilled in the art. Commonly in such a sensor, for example, red and green LEDs are used as the light source with selective colors. These light sources are most often powered with current at a selected frequency, so their signal components in the detector signals can be easily filtered from diffuse interference signals using conventional techniques. Any light-sensitive devices such as photodiodes or phototransistors can be used as detectors.

[0031] To detect the presence of fluid, alternative embodiments of the sensor may check other properties, in particular the electrical properties of the pressure transducer section 12B. Electrodes from the outside can be connected to section 12B of the pressure transducer, and alternating current can be used to check the conductivity or capacity of the system. Depending on the fluid being detected, you can also use inductance measurement.

[0032] In the event that the sensor 24 does not detect the presence of blood, this sensor, via the connecting cable 24a emits a first signal to the control unit, not shown in Fig. 1. When the blood enters the pressure transducer section 12B as a result of a leak in the first protective filter 13 of the pressure transducer, the optical properties of the pressure transducer section 12B will change in a certain way and the sensor 24 will emit a second signal to the control unit that differs from the first signal. The sensor 24 will thus allow the system 40 to notify any user of the failure of the first pressure transducer protective filter 13.

In the embodiment shown in Fig. 1, the sensor 24 is placed between the housing 23 and the second protective filter 22 of the pressure transducer, i.e. not on the side that is directly accessible to the user, who usually has direct access to the connecting means 14 to be able to replace part 10 disposable. In Fig. 1 an alternative arrangement is also shown where a sensor 24 "is located between the housing 23 and the housing connector 14B. Depending on the specific device, one of two variants may be preferred.

[0034] Fig. 2 shows a blood dialysis device with an extracorporeal circuit, comprising a first system 40 and a second identical system 40 'as shown in Fig. 1. In patient blood dialysis (not shown) blood circulates in the extracorporeal circuit 7 from the arterial line 11 to hemodialyser 1. Hemodializer 1 is divided by a semi-permeable membrane 2, which is usually made of a package of hollow fibers, into a first chamber 3 (blood chamber), which is part of the extracorporeal blood circuit 7, and a second chamber 4 (dialysate chamber), which is part of the dialysis circuit 8. Substances that are to be removed during blood processing penetrate through the membrane 2 from the blood chamber 3 into the dialysate chamber 4 and are removed through the dialysate which flows through the dialysate chamber 4. At the same time, excess fluid in the blood can be removed from the blood by applying an appropriate pressure gradient to the membrane 2. A diffusion gradient can be used to transfer substances present in fresh dialysate, such as electrolytes, into the blood, or to remove them from the blood to achieve a certain level of blood concentration of these substances.

[0035] Blood circulates thanks to the blood pump 5, which can be a conventional roller pump. Blood enters chamber 3 of dialyzer 1 through arterial blood line 11 and exits it through venous blood line 11 'through which it is reintroduced into the patient's body (not shown). The venous clamp 6 is located on the venous blood line 11 '. The venous clamp 6 can be clamped at any time when reintroduction should be interrupted for safety reasons. An example of a security reason is that the air sensor (not shown) detects a certain amount of air in venous blood 11 '.

[0036] The second chamber 4 of the hemodialysis device 1 is connected to the dialysate inlet line 30 through which the dialysate fluid is directed from the dialysate preparation assembly 34 to the second chamber 4. It is also connected to the dialysate outlet line 31 through which the dialysate is directed from the second chamber 4 to drain 35. The dialysate circulates thanks to the pumping and balancing means 32 and 33 by which the fluid maintains the parameters in the inlet and outlet lines 30 and 31 in the same way the ultrafiltration parameters through which the fluid is excreted from the blood can also be precisely controlled. Embodiments of pumping and balancing means 32 and 33 are well known in the art. The same applies to the 34 dialysate preparation team. An embodiment of the pumping and balancing means 32 and 33 and the dialysate preparation assembly 34 is described in US 4,267,040.

[0037] Conventional hemodialysis devices contain many other components that are well known in the art. For simplicity, the description of Figure 2 is limited to those components that appear to be sufficient to understand the concept of the present invention.

[0038] The hemodialysis device is controlled and monitored by the control unit 100. For this reason, the control unit 100 is connected to various sensors and actuators by means of signal connections. These can be wired or wireless connections. In Fig. 2, these connections are schematically shown using the same references for connections and attached sensors / actuators, where the terminal 'a' is added to the connection mark. For the sake of clarity only, only those connections that end in the control unit 100 are shown in fig. 2.

[0039] The control unit 100 is then connected to the input / output assembly 102 via the data link 101. Input / output assembly 102 may include a touch screen 103 that can be used to display selected information provided by the control unit 100. At the same time, the user can use the touch screen 103 to enter data and / or instructions into the control unit 100.

[0040] The hemodialysis device, which is shown in figure 2, also includes a system 40 according to the invention, as shown in detail in figure 1. From the arterial blood line 11 of the extracorporeal blood circuit 7, the pressure transducer line 12 branches off and leads to the pressure transducer blood. The system 40 is only symbolically represented in Figure 2. The same applies to an identical 40 'system that includes a pressure transducer 12' branching off the venous blood line 11 'and leading to the venous pressure transducer.

[0041] The wire connections 21a and 24a as shown in figure 1 are connected to the control unit 100 as shown in figure 2. This also applies to connections 21a 'and 24a' of the second system 40 '. Through these connections, the control unit 100 receives signals from the sensor 24 of the system 40 and the corresponding sensor 24 'of the system 40'. The sensors emit a first signal to the control unit 100 if the blood has not been detected by the sensor, and a second signal if the blood has been detected. This terminology is not limited to the system and device where the sensor processes the measured signal and as a result sends only two types of signals with the meaning of "yes" or "no". The sensor can send signals that are partially pre-processed or not processed at all. The first signal only needs to be distinguished from the second. The first signal may therefore be in the first range of signal values, and the second signal in the second range of signal values, and both ranges are separated by a threshold value. In the event that the signals are not pre-processed and the sensor creates double or multiple signals, as in the case of an optical sensor that checks transparency on two wavelengths, such double or multiple signals will be processed directly by the control unit 100. Although in this case the final value of transparency is calculated by the control unit, the transmission of such a double or multiple signal allowing the output of the final result is considered to be covered by the formulation that the sensor emits first and second signals depending on the presence of fluid in section 12B of the pressure transducer.

[0042] In the event that at least one of the sensors 24 or 24 'emits a second signal to the control unit 100, this unit sends the corresponding signal to the input / output assembly 102 so that an alarm signal is displayed on the touch screen 103 which will make the user aware of a problem with filter integrity protective pressure transducer in any of the pressure transducer lines. It is best if the user is notified in which of the two pressure transducer lines the alarm condition has been detected. The control unit 100 may also initiate sending other alarm signals such as an acoustic signal and / or sending signals via a telecommunications network to remote locations. Optionally, the control system 100 may, as feedback, recommend closing the venous blood line 11 'through venous clamp 6 and stopping the pumps or, if necessary, switching to special hold mode.

[0043] Because after processing of the blood, the blood lines of the extracorporeal blood circuit 7 are usually abolished, the corresponding set of blood lines only contains the set of disposable systems 40 and 40 ', respectively. The hemodialysis device itself, without the blood line, should only contain the reusable device components 20 of the 40 and 40 'systems as outlined above in the context of the description of Fig. 1. In this case, the housing 23 should be the housing of the hemodialysis device. The housing connector 14B is attached to the outside of the housing to which the user can attach the disposable blood line connector 14A. It is desirable that the other components of the reusable device 20 be located inside the housing 23 or at least as shown in Figure 1. In the event of a damaged part such as when blood is detected by the sensor 24, the user only needs to access these components. It may therefore be necessary to replace section 12F of the pressure transducer housing 12 and second pressure transducer filter 22. The housing 23 of the hemodialysis device may then be opened as in the case of technical maintenance or other suitable means to allow access to the components.

[0044] With the help of the sensor 24, the control unit 100 can check the integrity of the system at any time before, during and after blood processing. In particular, during the initial commissioning process, checking integrity by checking for the presence of fluid used during commissioning may help to avoid any other occurrence of defects during blood processing, which may occur if the check only occurs during blood processing. Checking should be carried out regularly to ensure that the sensor works correctly when conventional techniques can be used to ensure safety in the event of damage. Detecting a problem right after blood processing is also helpful, as it allows you to quickly replace the necessary parts.

[0045] The system and device of the invention provides a simple and effective way to avoid blood contamination problems and undetectable damage to the pressure transducer protective filter, especially in blood processing devices where the pressure in blood lines must be routinely monitored in one or more places. As a result, a higher standard of hygiene can be achieved. The device according to the invention can be integrated into the blood processing device during the production process. Because the number of additional components is low, it is possible to easily use the device according to the invention in older blood processing devices by installing suitable retrofit kits. Such kits only require a software update of the control unit of the blood processing device and an additional sensor to detect the presence of fluid in the pressure transducer section of the pressure transducer line.

[0046] The invention can be used in any blood transfer line or other blood component for processing by a blood processing device. It is not limited to whole blood processing.