System for detecting blood in the dialysate flow of a dialyzer

Abstract

1. The invention relates to a method and a detection device for detecting blood in a dialysate flow of a dialyzer during extracorporeal blood treatment. 2. Use during extracorporeal blood treatment.

Description

Technical Field

[0001] The invention relates to a detection device and a method for detecting blood in a dialysate flow of a dialyzer during extracorporeal blood treatment. Background Art

[0002] The dialyzer provided for extracorporeal blood treatment has a dialyzer with a blood chamber and a dialysate chamber, which are separated from each other by a semipermeable membrane. During blood treatment, blood is transported through the blood chamber in the extracorporeal blood circulation. At the same time, the dialysate chamber is flowed through by the dialysate (which may also be referred to as dialysis liquid). When the semipermeable membrane breaks due to a fault, blood from the extracorporeal blood circulation may reach the dialysate flow. Such blood leakage may cause serious medical damage to the patient to be treated and cause technical failures at the dialyzer. For this reason, the dialyzer is usually provided with a detection device, by means of which the blood in the dialysate flow can be detected.

[0003] Such a detection device is known from US 4,181,610 B1. The known detection device has a first light source and a second light source, which are arranged together on a first side of a light-permeable fluid guide channel for fluid-guiding a dialysate flow and emit light of different wavelengths. In addition, the known detection device has a control device, which is set up to alternately control the two light sources, so that the light of the light sources is alternately injected into the dialysate flow. A single detector is arranged on the opposite side of the fluid guide channel, which is set up to detect the light portions of the two light sources transmitted by the dialysate flow and generate corresponding signals. Here, the first signal represents the intensity of the light portion of the transmission of the first light source detected. The second signal represents the intensity of the light portion of the transmission of the second light source detected. In the case of blood leakage, the light injected by the first light source is absorbed more strongly than the light injected by the second light source due to its wavelength. Thus, blood leakage can be detected by comparing the first signal and the second signal. In addition, the known detection device includes a calibration device, which is set up to calibrate the brightness of the two light sources. This is intended to prevent brightness changes between the two light sources caused by operation from being erroneously interpreted as blood leakage. Summary of the invention

[0004] The object of the present invention is to provide a detection device and a method of the type mentioned at the outset which enable a simplified design or simplified execution compared to the prior art and at the same time enable reliable detection of blood in the dialysate flow.

[0005] This object is achieved by providing a method according to the invention having the features of claim 1 and a detection device according to the invention having the features of claim 6 .

[0006] The method according to the invention comprises the following steps: a) injecting light into the dialysate flow; b) detecting the light component of the injected light transmitted through the dialysate flow at a first detection position and generating a first signal, which represents the intensity of the detected transmitted light component; c) detecting the light component of the injected light scattered in the dialysate flow at a second detection position and generating a second signal, which represents the intensity of the detected scattered light component; d) generating a detection signal based on the generated first signal and the generated second signal. According to the solution of the invention, a complex calibration of the brightness of the injected light can be omitted. This is because possible intensity fluctuations of the injected light have the same influence on the transmitted light component and the scattered light component. Accordingly, the first signal and the second signal change positively or negatively in the case of intensity fluctuations of the injected light. In contrast, as the blood concentration in the dialysate flow increases, the intensity of the transmitted light component decreases, while the intensity of the scattered light component increases at the same time. Accordingly, in the case of blood leakage (unlike in the case of brightness fluctuations of the injected light), the first signal and the second signal change in opposite directions. This can be taken into account when generating the detection signal from the first signal and the second signal. The method according to the invention thus enables simple and yet reliable detection of blood in the dialysate flow, since false detections due to brightness fluctuations of the incident light are avoided, while calibration associated therewith is also omitted.

[0007] Step a) comprises injecting light into the dialysate flow. The inventors have recognized that the injection of light visible to humans is particularly advantageous. In this regard, for example, red light, green light or blue light can be injected, wherein "red" and "blue" represent the limits of the visible spectrum. Because this can avoid negative influences on the detection due to urine substances located in the dialysate flow. In addition, it is recognized that the injection of blue light provides advantages in terms of particularly sensitive detection of light, especially in step c). Preferably, the light is injected with an injection direction oriented transversely, preferably perpendicularly to the flow direction of the dialysate flow. The light can be injected continuously and / or discretely in time.

[0008] Step b) includes detecting the light component of the incident light that is transmitted through the dialysate flow. In the case of blood leakage, the intensity of the detected transmitted light component is reduced. This is due to the absorption effect, reflection effect and / or scattering effect of the blood particles of the infiltrated blood. The "sum" consisting of absorption, scattering and other effects that reduce light intensity can also be called extinction. Step b) also includes generating a first signal. Since the first signal represents the intensity of the detected transmitted light component, in the case of blood leakage, the first signal, in particular its value, changes accordingly. Preferably, in the case of blood leakage, the first signal decreases. In other words, in the case of blood leakage, the value of the first signal decreases over time. In other words, in the case of blood leakage, the time variation of the first signal is preferably negative. The first signal can be generated discretely in time and / or continuously in time.

[0009] Step c) comprises detecting the light component of the incident light that is scattered in the dialysate flow. In the event of a blood leak, the concentration of light-scattering blood particles in the dialysate flow increases. Correspondingly, in the event of a blood leak, the intensity of the scattered light component increases. In addition, step c) comprises generating a second signal. Since the second signal represents the intensity of the detected scattered light component, the second signal, in particular its value, changes accordingly. Preferably, in the event of a blood leak, the second signal increases. In other words, in the event of a blood leak, the temporal variation of the second signal is preferably positive. The second signal can be generated time-continuously and / or time-discretely.

[0010] Step d) comprises generating a detection signal. The detection signal can be, in particular, a signal for controlling at least one function of a detection device for carrying out the method, a signal for controlling at least one function of a dialyzer and / or a signal perceptible by a user of the method, in particular an acoustic and / or optical signal. The detection signal is generated as a function of the generated first signal and the generated second signal. In this context, in particular, the value, sign, magnitude, time change, time change rate, etc. of the corresponding signal can be evaluated.

[0011] In a design of the invention, a detection signal is generated if the time variation of the first signal is opposite to the time variation of the second signal. Thus, a detection signal is generated if the first signal, in particular its value, decreases over time while the second signal, in particular its value, increases over time, or vice versa. This is a particularly advantageous design of the invention.

[0012] In another embodiment of the present invention, the method comprises the following steps: e) emitting ultraviolet light, wherein the ultraviolet light is injected into the dialysate flow and radiates through the dialysate flow; f) detecting the ultraviolet light component of the injected ultraviolet light that is transmitted through the dialysate flow at a first detection position, and generating a third signal, the third signal representing the intensity of the detected transmitted ultraviolet light component; g) detecting the ultraviolet light radiated through the dialysate flow at a second detection position, and generating a fourth signal, the fourth signal representing the intensity of the detected ultraviolet light radiated through; h) determining the Kt / V value based on the generated third signal and the generated fourth signal. This is a particularly preferred embodiment of the present invention. Because this embodiment realizes the additional determination of the so-called Kt / V value when the ultraviolet light intensity required for this is detected "at the same position". The term "Kt / V value" or "Kt-V" for short is known per se in the field of medical technology. The Kt / V value is related to the urea concentration in the dialysate flow. If the relative change in the urea concentration is known, the Kt / V value can be determined based on known chemical and / or physical relationships. The change in urea concentration is related to the change in the generated third signal. In other words: the urea concentration in the dialysate flow is a marker for the progress of the extracorporeal blood treatment; the lower the concentration in the dialysate flow, the lower the concentration in the patient's blood to be treated; the relative measurement of this concentration allows the determination of the Kt / V value. Therefore, it is known that the Kt / V value allows the progress of the extracorporeal blood treatment and therefore in particular the required treatment duration to be inferred. The UV light intensity required for determining the Kt / V value is detected at the first detection position and at the second detection position, and therefore at the detection position for blood leakage detection. This allows a great simplification of the execution of the method and also a great simplification of the structure of the detection device set up for executing the method. In this context, this design of the present invention therefore relates to a method for detecting blood and toxins, especially urea, in the dialysate flow of a dialyzer during extracorporeal blood treatment. Since the method according to this design of the present invention is not only provided for detecting blood but also for detecting toxins, it can also be called "combined detection".

[0013] Step e) comprises emitting ultraviolet light. The emitted ultraviolet light is injected into the dialysate flow and radiates through the dialysate flow. The ultraviolet light is preferably injected into the dialysate flow in an injection direction oriented transversely to, preferably perpendicular to, the flow direction of the dialysate flow. Further preferably, the ultraviolet light and the light (to be injected according to step a)) are injected into the dialysate flow in a common plane. The ultraviolet light can be emitted, injected into and / or radiated continuously and / or discretely in time. Preferably, the ultraviolet light radiates through the dialysate flow in a radiation direction oriented transversely to, preferably perpendicular to, the flow direction of the dialysate flow.

[0014] Step f) includes detecting the UV light component of the injected UV light that is transmitted through the dialysate flow. As the urea concentration increases, the intensity of the transmitted UV light decreases. This is due to absorption effects, reflection effects and / or scattering effects. In addition, step f) includes generating a third signal. Since the third signal represents the intensity of the detected transmitted UV light component, the third signal, in particular its value, decreases as the urea concentration in the dialysate flow increases. The third signal can be generated time-continuously and / or time-discretely. The transmitted UV light component is detected at the first detection position and therefore at the position where the transmitted light component of the light injected for blood detection has been detected.

[0015] Step g) includes detecting the ultraviolet light radiating through the dialysate flow. The ultraviolet light is radiated directly or, if necessary, once or more times in the direction of the second detection position and is detected there (also like the scattered light component of the light injected for blood detection). In addition, step g) includes generating a fourth signal. The fourth signal represents the intensity of the detected ultraviolet light and acts as a reference signal for the third signal. Because the intensity of the ultraviolet light radiating through is independent of the urea concentration. Therefore, when evaluating the third signal and the fourth signal, possible fluctuations in the brightness of the emitted ultraviolet light can be identified by itself. The fourth signal can be generated continuously and / or discretely in time.

[0016] Step h) comprises determining the Kt / V value. This determination is carried out based on the generated third signal and the generated fourth signal. Here, the fourth signal acts as a reference signal. The third signal represents the intensity of the detected transmitted UV light component, which in turn is related to the UV light absorption. It is known that there is an approximately linear relationship between the UV light absorption and the urea concentration in the dialysate flow, so that the Kt / V value is determined based on a relationship known in principle.

[0017] In a further embodiment of the invention, the second detection position is shielded from the UV light incident into the dialysate flow. This prevents the UV light incident into the dialysate flow from being diverted in the direction of the second detection position directly, reflected or by other optical effects and from distorting the detection of the UV light radiating there and thus the generation of the fourth signal in an undesirable manner.

[0018] In a further embodiment of the invention, light and ultraviolet light are injected into the dialysate flow alternately, preferably at an alternating frequency of 1 kHz, wherein the first signal and the third signal are generated alternately by means of a first detector arranged at a first detection position, and wherein the second signal and the fourth signal are generated alternately by means of a second detector arranged at a second detection position. This is a particularly preferred embodiment of the invention. In the case of a sufficiently high alternating frequency, blood leakage detection and Kt / V value determination can be performed approximately simultaneously.

[0019] The detection device according to the invention is designed to perform the above method and has: at least one light source, which is designed to emit light into the dialysate flow; a first detector, which is arranged at a first detection position, wherein the first detector is designed to detect the light component of the incident light that is transmitted through the dialysate flow and generate a first signal, which represents the intensity of the detected transmitted light component; a second detector, which is arranged at a second detection position different from the first detection position, wherein the second detector is designed to detect the light component of the incident light that is scattered in the dialysate flow and generate a second signal, which represents the intensity of the detected scattered light component; and an evaluation unit, which is designed to generate a detection signal based on the first signal and the second signal. Through the solution according to the invention, in particular, a calibration device for calibrating the brightness of the light source can be omitted. Because possible fluctuations in the brightness of the light source or the light emitted by it caused by operation are detected in the same way by means of the first detector and the second detector. This can be taken into account when generating the detection signal by means of the evaluation unit. Therefore, the detection device according to the invention realizes a simple structure and still reliable detection of blood in the dialysate flow, because erroneous detections caused by brightness fluctuations of the light source can be avoided, while the calibration device is omitted. In particular, the light source is set up to implement step a) of the method according to the present invention. Preferably, the light source is a light emitting diode. Further preferably, the light source is set up to emit red light, green light and / or blue light, and in this regard is, for example, a red, green and / or blue light emitting diode. In particular, the first detector is set up to implement step b) of the method according to the present invention. Preferably, the first detector is a photodiode. The second detector is particularly set up to implement step c) of the method according to the present invention. Preferably, the second detector is a photodiode. The first detector and the second detector are arranged at different positions, namely at the first detection position and the second detection position. In this regard, the first detector and the second detector are spaced apart from each other. The evaluation unit is particularly set up to implement step d) of the method according to the present invention. In order to avoid repetition, in other cases, reference is made to the explanation of the features and advantages of the method according to the present invention. The content described there can be appropriately transferred to the device of the detection device, in particular the light source, the first detector, the second detector and / or the evaluation unit.

[0020] In a further embodiment of the invention, the evaluation unit is configured to generate a detection signal as a function of the time variation of the first signal and the time variation of the second signal. In this regard, the evaluation unit is particularly configured to implement the method according to the invention as claimed in claim 2. In the remainder, in addition and to avoid repetition, reference is made to the disclosure related to the above-mentioned embodiment of the method according to the invention, which can be appropriately transferred to this embodiment of the detection device according to the invention.

[0021] In another embodiment of the present invention, a light source is arranged on a first side of a light-permeable fluid guiding channel, the fluid guiding channel being arranged for fluid guiding a dialysate flow along its longitudinal direction, a first detector being arranged on a second side of the fluid guiding channel spaced apart from the light source in the direction of light injection, the second side being arranged transversely to the longitudinal direction of the fluid guiding channel and opposite to the first side, and a second detector being arranged on the second side of the fluid guiding channel and spaced apart from the first detector perpendicularly to its longitudinal direction. The fluid guiding channel is preferably made of transparent plastic or glass. In particular, the fluid guiding channel can be designed as a hose section, a tube section and preferably as a cuvette. Further preferably, the fluid guiding channel has a circular cross section. The fluid guiding through the fluid guiding channel is carried out in the longitudinal direction of the fluid guiding channel. The light source and the first detector are arranged on opposite sides of the fluid guiding channel, i.e., the first side and the second side. Preferably, the light source and the first detector are arranged in a common central longitudinal plane and / or a central transverse plane of the fluid guiding channel. In this regard, the direction of incidence of the light is oriented transversely to the longitudinal direction of the fluid-conducting channel and thus also transversely to the flow direction of the dialysate flow. Preferably, a vertical orientation of the direction of incidence is provided, i.e. an orientation at 90° to the longitudinal direction or the flow direction. Preferably, the second detector is arranged offset upwards or downwards relative to the first detector (with respect to an optical axis extending directly between the light source and the first detector and in a viewing direction pointing perpendicularly to the cross section of the fluid-conducting channel).

[0022] In another embodiment of the present invention, the second detector is arranged at an angle between 5° and 30°, preferably between 18° and 22°, to the incident direction of the light. The optical axis extending directly between the light source and the first detector extends along the incident direction. In this regard, the second detector is arranged at the above-mentioned angle to the optical axis. The angle between 5° and 30° enables a functional detection of the light component scattered in the dialysate flow. In addition, the inventors have also recognized that an angle between 18° and 22°, particularly preferably 20°, provides special advantages for the detection of the scattered light component.

[0023] In another embodiment of the present invention, a UV light source is provided, which is configured to inject UV light into the dialysate flow and radiate the UV light through the dialysate flow; a first detector is configured to detect the UV light portion of the injected UV light that is transmitted through the dialysate flow and to generate a third signal, which represents the intensity of the detected transmitted UV light portion; a second detector is configured to detect the UV light radiated through the dialysate flow and to generate a fourth signal, which represents the intensity of the detected UV light radiated through the dialysate flow; and an evaluation unit is configured to determine the Kt / V value based on the generated third signal and the generated fourth signal. This embodiment of the detection device according to the present invention enables the execution of the method according to the present invention as configured in claim 3. In order to avoid repetition, reference is made to the disclosure of the embodiment of the method according to the present invention, wherein the features and advantages explained therein can be appropriately transferred to this embodiment of the detection device according to the present invention. The UV light source is particularly configured to implement step e) of the method. The UV light source is preferably a light emitting diode. The UV light source is arranged relative to the dialysate flow and / or the fluid guiding channel in such a way that the emitted UV light can partially penetrate into the dialysate flow and can partially radiate through the dialysate flow. In other words, the UV light source is arranged in such a way that the first optical axis extends between the UV light source and the first detector, and therefore between the UV light source and a first detection position through the dialysate flow, and the second optical axis extends between the UV light source (and beside the dialysate flow and / or the fluid guiding channel) and the second detector, and therefore between the UV light source and the second detection position. In this embodiment of the invention, the first detector is additionally set up for carrying out step f of the method. In this embodiment of the invention, the second detector is additionally set up for carrying out step g of the method. In this embodiment of the invention, the evaluation unit is additionally set up for carrying out step h of the method. In the remaining cases, supplementally and in order to avoid repetition, reference is made to the disclosure related to the above steps e) to h) of the method according to claim 3, which can be appropriately transferred to the arrangement of the UV light source, the first detector, the second detector and / or the evaluation unit.

[0024] In another embodiment of the present invention, the ultraviolet light source is arranged on the first side of the fluid guiding channel. Preferably, the ultraviolet light source, the light source and the first detector and / or the second detector are arranged in a common plane.

[0025] In another embodiment of the present invention, a shielding element is provided, by means of which the second detector is shielded from the ultraviolet light incident into the dialysate flow. To avoid repetition, reference is made to the disclosure of the embodiment of the method according to the present invention according to claim 4, wherein said contents are appropriately applicable there. The shielding element is arranged in such a way that the detection of the scattered light component of the incident light and the detection of the ultraviolet light radiating through the dialysate flow by means of the second detector are not influenced by the shielding element. The shielding element is at least opaque for the wavelength of the emitted ultraviolet light. Preferably, the shielding element is substantially completely light-impermeable.

[0026] In another embodiment of the present invention, a control unit is provided, and the control unit is configured to alternately control the light source and the ultraviolet light source, preferably at an alternating frequency of 1 kHz. By alternating control, the light and the ultraviolet light are output alternately and thus intermittently in time, and are therefore also detected alternately by means of the first detector and the second detector accordingly. The control unit can be a separate unit of the detection device, or can be integrated into a single unit together with the evaluation unit.

[0027] In another embodiment of the invention, a housing is provided in which at least the light source, the first detector and the second detector are accommodated. In particular, this embodiment of the invention facilitates the assembly and maintenance of the detection device, because when the housing is manipulated, the components accommodated in the housing can be assembled together at the dialyzer and / or removed together from the dialyzer in a simple manner.

[0028] In another embodiment of the present invention, the UV light source and / or the shielding element are accommodated in the housing. This is a particularly preferred embodiment of the present invention, because an additional housing for accommodating the UV light source and / or the shielding element can be omitted. In other words, the components required for blood leakage detection and for determining the Kt / V value, in particular the optical element, are accommodated together in the housing.

[0029] The invention further relates to a dialyzer having a dialyzer and a detection device according to the above description arranged on the outlet side of the dialyzer. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Further advantages and features emerge from the claims and from the following description of preferred exemplary embodiments of the invention, which are illustrated with reference to the drawings.

[0031] Figure 1 A schematic diagram showing a section of one embodiment of a dialyzer according to the invention, which is provided with one embodiment of a detection device according to the invention;

[0032] Figure 2Show according to Figure 1 A schematic, highly simplified illustration of a detection device of , wherein the detection device is configured to carry out one specific embodiment of the method according to the invention;

[0033] Figure 3 Show corresponding to Figure 2 The illustration shows a further embodiment of the detection device according to the invention, wherein the detection device is configured to carry out a further embodiment of the method according to the invention;

[0034] Figure 4 Shown to further illustrate the Figure 2 A schematic diagram of the mode of operation of the detection device and the method that can be performed using the detection device;

[0035] Figure 5 Shown to illustrate the Figure 3 Further schematic diagrams of the mode of operation of the detection device and of the methods which can be performed with the detection device;

[0036] Figure 6 It is shown to further illustrate the use of Figure 2 A schematic flow chart of a method performed by a detection device; and

[0037] Figure 7 Shown to illustrate the use of Figure 3 A schematic flow chart of a method performed by a detection device. DETAILED DESCRIPTION

[0038] Figure 1 A section of an embodiment of a dialyzer 1 according to the invention is schematically shown, which is provided with an embodiment of a detection device 2 according to the invention. The dialyzer 1 is used for extracorporeal blood treatment and has a dialyzer 3 with a blood chamber 4 and a dialyzing fluid chamber 5. The blood chamber 4 is separated from the dialyzing fluid chamber 5 by means of a semipermeable membrane 6 and is connected in a fluid-conducting manner to an extracorporeal blood circuit (not shown in detail), in which the blood to be treated is conveyed through the blood chamber 4 along a flow direction BF. The dialyzing fluid chamber 5 is connected to a dialyzing fluid circuit (not shown in detail), in which a dialyzing fluid D (also referred to as dialysis fluid) is conveyed to the extracorporeal blood circuit. Figure 2 ) is transported through the dialysate chamber 5 along the flow direction DF while forming a dialysate flow DS.

[0039] During the extracorporeal blood treatment, urine substances are transferred from the blood conveyed through the blood chamber 4 via the semipermeable membrane 6 into the dialysate flow DS conveyed through the dialysate chamber 5. These urine substances include in particular urea H, which is referred to as urea H for the sake of clarity of the diagram. Figure 2In a highly simplified form, blood B is schematically shown in the dialysate flow DS in the form of particles or drops. In a well-functioning state of the semipermeable membrane 6, blood is sealed in the blood chamber 4 in a fluid-tight manner relative to the dialysate chamber 5. In the event of a rupture of the semipermeable membrane 6 caused by a fault, blood penetrates from the blood chamber 4 into the dialysate chamber 5 via the rupture and thus into the dialysate flow DS. For the sake of clarity of the diagram, the blood B that penetrates into the dialysate flow DS in this way is schematically shown in a highly simplified manner in the form of particles or drops. Such blood leakage can lead to serious medical complications in the patient to be treated and to technical damage to the dialyzer 1.

[0040] The detection device 2 is used to detect blood B that has penetrated into the dialysate flow DS. For this purpose, the detection device 2 is arranged on the outlet side of the dialysate chamber 5 in the flow direction DF and is flowed through by the dialysate flow DS in the installed state ready for operation. In order to guide the fluid of the dialysate flow DS, a fluid guide channel 7 is provided at least in the area of ​​the detection device 2. In the embodiment shown, the fluid guide channel 7 is constructed as a section of the dialysate circulation on the instrument side and is not a component of the detection device 2 in this respect. In an embodiment not shown, the fluid guide channel is instead a component of the detection device, which is connected to the dialysate circulation on the instrument side in a fluid-guiding manner on the inlet side and the outlet side of the detection device.

[0041] If with the help of Figure 2 As shown, the detection device 2 has a light source 8 , a first detector 9 , a second detector 10 and an evaluation unit 11 .

[0042] The light source 8 is designed to emit light L into the dialysate flow DS. The first detector 9 is arranged at a first detection position E1, which detects the light L in the dialysate flow DS. Figure 2 The first detector 9 is shown in the center of the schematic diagram in a simplified manner. The first detector 9 is configured to detect a light component LT of the incident light L transmitted by the dialysate flow DS and to generate a first signal S1. Here, the first signal S1 represents the intensity of the detected transmitted light component LT. The second detector 10 is arranged at a second detection position E2, which is arranged spaced apart from the first detection position E1 in a manner described in further detail. Here, the second detector 10 is configured to detect a light component LS of the incident light L scattered in the dialysate flow DS and to generate a second signal S2. The second signal S2 represents the intensity of the detected scattered light component LS. The evaluation unit 11 is configured to generate a detection signal Z based on the first signal S1 and the second signal S2. More precisely, in the embodiment shown, the evaluation unit 11 is configured to generate a detection signal Z based on the first signal S1 and the second signal S2. Figure 4 The time variation of the first signal S1 and the time variation of the second signal S2 , which shall also be explained in more detail, generates the detection signal Z.

[0043] In order to detect the blood B that has penetrated into the dialysate flow DS in the above-described manner, light L is injected into the dialysate flow DS through a light-transmissive fluid guide channel 7 with the aid of a light source 8. The injected light L is partially scattered in the dialysate flow DS at the blood B located in the dialysate flow DS and is absorbed by it. The transmitted light component LT generated here is detected at a first detection position E1 with the aid of a first detector 9 and converted into a first signal S1. The scattered light component LS generated here is detected at a second detection position E2 with the aid of a second detector 10 and converted into a second signal S2. The signals S1, S2 are processed with the aid of an evaluation unit 11, which for this purpose is connected both to the first detector 9 and to the second detector 10 with the aid of a signal line that is not shown in detail. In the illustrated embodiment, a detection signal Z is generated when the temporal changes of the signals S1, S2 are opposite to each other. This is described below with the aid of Figure 4 To explain.

[0044] Figure 4 A first signal S1 and a second signal S2 are shown over time t for an exemplary course of extracorporeal blood treatment by means of a dialyzer 1. As described above, the exemplary course of the signals S1, S2 represents a detected transmitted light component LT and a detected scattered light component LS, respectively, so that the course of the transmitted light component and the scattered light component is plotted in accordance with the course of the signals S1, S2. In addition, according to Figure 4 The diagram shows the time course of the blood concentration BK of blood B and the urea concentration HK of urea H in the dialysate flow DS over time t. The exemplary extracorporeal blood treatment provides for so-called priming, i.e. ventilation, of the dialysate circulation between time points t1 and t2. Here, the dialysate circulation is filled with dialysate D, wherein in particular air rushes out of the fluid guide channel 7 and is replaced by the dialysate D. Due to the different optical properties of air and dialysate D, the transmitted light component and the scattered light component LT and LS naturally vary. The transmitted light component and the scattered light component increase at time point t1. The same applies to the signals S1, S2.

[0045] At time t2, the actual blood treatment begins, in which urine substances, in particular urea H, are transferred from the blood chamber 4 into the dialysate flow DS via the semipermeable membrane 6. Accordingly, the urea concentration HK increases at time t2. The change in the transmitted light component LT and / or the scattered light component LS is not caused by the increased urea concentration HK.

[0046] The urea concentration HK remains constant until time t3. The urea concentration HK then begins to decrease, which continues until time t4. This temporal change in the urea concentration HK also has no effect on the signals S1, S2 and / or the light components LT, LS. That is, the light component LT and therefore also the first signal S1 remain unaffected. The light component LS and therefore also the second signal S2 remain unaffected.

[0047] From the time t4 onwards, no further change in the urea concentration H occurs.

[0048] At time t5, a rupture occurs at the semipermeable membrane 6, so that blood is transferred from the blood chamber 4 into the dialysate chamber 5 and thus into the dialysate flow DS. This leads to an increase in the blood concentration BK. The increased blood concentration BK leads to an intensified scattering of the incident light L at the infiltrated blood B ( Figure 2 ). Accordingly, the scattered light component LS increases at time t5. This increase in the scattered light component LS causes a corresponding time change in the second signal S2. At the same time, an opposite time change in the transmitted light component LT and thus also in the first signal S1 is caused.

[0049] The above-described opposite time course of the light components LT, LS and therefore also the first signal S1 and the second signal S2 is a clear indicator for the blood leakage BK occurring at the time t5. Accordingly, the detection signal Z is output by means of the evaluation unit 11 when such an above-described opposite time course of the signals S1, S2 is present.

[0050] In the present embodiment, the detection signal Z is an acoustic and / or optical warning signal perceptible by a user of the dialyzer 1. In an embodiment not shown, the detection signal Z is a control signal for controlling at least one function of the dialyzer 1. For example, the dialyzer 1 can be controlled with the aid of the detection signal Z in order to interrupt the extracorporeal blood treatment, in which case the transport of blood in the blood circulation and / or the transport of dialysate D in the dialysate circulation is interrupted.

[0051] Furthermore, it goes without saying that the rupture, which in the present case occurs by way of example at time t5 , can of course also take place instead at any other time of the extracorporeal blood treatment, for example before time t4 .

[0052] In the embodiment shown, the light source 8 is arranged on a first side (not shown in detail) of the light-permeable fluid-conducting channel 7. Both the first detector 9 and the second detector 10 are arranged on a second side of the fluid-conducting channel 7, which is opposite the first side and therefore also opposite the light source 8 transversely, more precisely perpendicularly, to the flow direction DF of the dialysate flow DS. Figure 2The drawing plane of the image is oriented so as to protrude perpendicularly from the image plane. In other words, the first detector 9 is arranged along the incident direction R1 of the light L so as to be spaced apart from the light source 8 .

[0053] In the present embodiment, the light source 8 and the first detector 9 are each arranged at the height of a central transverse axis (not shown in detail) of the fluid-conducting channel 7. The imaginary optical axis between the light source 8 and the first detector 9 and thus the first detection position E1 is therefore oriented coaxially with the central transverse axis of the fluid-conducting channel 7.

[0054] The second detector 10 is arranged offset relative to the central transverse axis of the fluid-conducting channel 7. The second detector 10 is arranged at an angle (not shown in detail) to the incident direction R1 of the light beam L. In other words, the second detector 10 is positioned at an angle (not shown in detail) to the center point M of the fluid-conducting channel 7. Figure 2 Unlike what is envisaged, the angle to the injection direction R1 and thus to the central transverse axis of the fluid-conducting channel 7 is in the present case 20°.

[0055] In the embodiment shown, the light source 8 , the first detector 9 and the second detector 10 are arranged in a common plane.

[0056] In accordance with Figure 2 In an embodiment, the light source 8 is a light emitting diode. In order to control the light source, a control device 12 is currently provided. The light source 8 can control the light L for time-continuous and / or time-discrete, i.e. intermittent, emission by means of the control device 12. The first detector 9 and the second detector 10 are respectively photodiodes. The evaluation unit 11 and the control unit 12 can (e.g. Figure 2 In one embodiment, the evaluation unit and the control unit are integrated into a common unit.

[0057] according to Figure 3 The detection device 2a has the following Figure 2 The detection device 2 has a largely identical structure. In order to avoid repetition, reference is made to Figure 2 The disclosures concerning the detection device 2 of FIG. 1 also apply to the detection device 2a in the same sense. In the following, only the essential differences of the detection device 2a are discussed. Due to these differences, the detection device 2a is designed to perform the detection by means of Figure 5 and Figure 7 Schematically illustrated method for detecting blood and urea in a dialysate flow DS.

[0058] The detection device 2a differs from the detection device 2 essentially in that a UV light source 13 is provided. The UV light source 13 is designed to inject UV light U into the dialysate flow DS and radiate the UV light U through the dialysate flow DS. The first detector 9a corresponds to Figure 2 The first detector 9 of the detection device 2 is set up. In addition, the first detector 9a is set up to detect the ultraviolet light component UT of the incident ultraviolet light U transmitted through the dialysate flow DS and generate a third signal S3. The third signal S3 represents the intensity of the detected transmitted ultraviolet light component UT. The second detector 10a corresponds to Figure 2 The second detector 10 of the detection device 2 is set up. In addition, the second detector 10a is set up to detect the ultraviolet light U radiating through the dialysate flow DS and generate a fourth signal S4. The fourth signal S4 represents the intensity of the detected ultraviolet light U radiating through. The evaluation unit 11a is based on Figure 2 The evaluation unit 11 of the detection device 2 is set up. In addition, the evaluation unit 11a is set up to determine the Kt / V value K based on the generated third signal S3 and the generated fourth signal S4.

[0059] The Kt / V value K is a parameter that is basically known in the field of dialysis technology and can be used to infer the progress of the extracorporeal blood treatment. It is known that the Kt / V value K is determined based on the urea concentration HK of the urea H in the dialysate flow DS. It is known that the urea concentration HK has an approximately linear relationship with the absorption of the ultraviolet light U injected into the dialysate flow DS. Correspondingly, the transmitted ultraviolet light portion UT changes according to the urea concentration HK. Such changes are detected by means of the first detector 9a and converted into a third signal S3. Here, the ultraviolet light U radiated through the dialysate flow DS is detected by means of the second detector 10a and converted into a fourth signal S4 as a reference. The evaluation operation that should be implemented by means of the evaluation unit 11a for determining the Kt / V value K based on the third signal S3 and the fourth signal S4 is basically known per se, so that further explanations related to this can be omitted.

[0060] Figure 5 With Figure 4 In a corresponding manner, an exemplary course of extracorporeal blood treatment with the aid of the dialyzer 1 is shown at time t and using the detection device 2a. The exemplary course of the signals S1, S2 shown there or the corresponding course of the transmitted light component LT and the detected scattered light component LS is shown with the aid of Figure 4 The already explained course of events corresponds to this. This also applies to the urea concentration HK and the blood concentration BK. To avoid repetition, reference is made to the combined Figure 4 explanations related to this.

[0061] Figure 5In addition, a third signal S3 and a fourth signal S4 are shown over time. As already mentioned above, the exemplary shown course of the signals S3 , S4 represents the intensity of the detected transmitted UV light component UT or the intensity of the detected UV light U that radiates through.

[0062] As the urea concentration HK increases at time t2, the extinction of the UV light injected into the dialysate flow DS intensifies, so that the transmitted UV light portion UT decreases and accordingly the third signal S3 also decreases. The intensity of the detected UV light U passing through remains unaffected and thus the fourth signal S4 also remains unaffected.

[0063] As the urea concentration HK starts to drop at time t3, the transmitted UV light portion UT increases, and thus the third signal S3 also increases. This situation continues until time t4. From time t4 onwards, the urea concentration HK remains unchanged.

[0064] In addition, due to the blood leakage at time t5, the transmitted UV light component UT decreases, and thus the third signal S3 also decreases. This change of the third signal S3 has no practical effect on the determination of the Kt / V value K, because after the blood leakage occurring at time t5 is detected, the extracorporeal blood treatment is interrupted anyway.

[0065] In the embodiment shown, the UV light source 13 is arranged in a common plane with the first detector 9a and the second detector 10a. Therefore, all optical elements 8, 9a, 10a, 13 are currently located in a common plane. The UV light source 13 is arranged offset downward relative to the fluid guide channel 7 and the light source 8, so that the UV light of the UV light source 13 can be directly radiated in the direction of the second detection position E2 and therefore also directly radiated in the direction of the second detector 10a. In this regard, this radiation is carried out through the fluid guide channel 7.

[0066] In addition, the detection device 2a has a shielding element 14, which is arranged relative to the fluid-conducting channel 7, the ultraviolet light source 13 and / or the second detector 10a in such a way that the second detector is shielded from light components of the incident ultraviolet light U that are scattered in the dialysate flow DS or otherwise deflected in the direction of the second detection position E2 by means of the shielding element 14. At the same time, the shielding element 14 is arranged in such a way that the light component LS of the incident light L that is scattered in the dialysate flow DS can be detected by means of the second detector 10a.

[0067] In accordance with Figure 3In the embodiment of the invention, the control device 12a is configured to alternately control the light source 8 and the ultraviolet light source 13. The control is preferably performed at an alternating frequency of 1 kHz. In other words, the light L and the ultraviolet light U are injected into the dialysate flow DS alternately in time and are correspondingly converted into signals S1, S2 and S3, S4 alternately in time by means of the first detector 9a and the second detector 10a. In the case of a sufficiently high alternating frequency, the generation of the detection signal Z and the determination of the Kt / V value K are performed approximately simultaneously in practice.

[0068] If further aided Figure 1 As shown, a housing 15 is provided. Figure 2 In the embodiment of the present invention, the housing 15 at least accommodates the light source 8, the first detector 9 and the second detector 10. In addition, the evaluation unit 11 and the control unit 12 can be accommodated in the housing 15.

[0069] The same applies to Figure 3 , so that a housing for accommodating essentially all components of the detection device 2a can also be provided there.

[0070] Figure 6 Show that it can be based on Figure 2 Schematic, highly simplified flow chart of a method for detecting blood performed by a detection device 2 of the present invention, said method comprising steps a) to d). In addition, reference is made to the wording of claim 1. Figure 7 Show available basis Figure 3 Schematic, highly simplified flow chart of a method for detecting blood and urea, performed by a detection device 2a of the invention, said method comprising steps a) to h). In addition to this, reference is made to the wording of claims 1 and 3.

Claims

1. A method for detecting blood (B) in a dialysate flow (DS) of a dialyzer (1) during extracorporeal blood treatment, the method comprising: The following steps are involved: a) injecting light (L) into the dialysate flow (DS); b) detecting at a first detection position (E1) a light component (LT) of the incident light (L) which is transmitted through the dialysate flow (DS), and generating a first signal (S1) which represents the intensity of the detected transmitted light component (LT); c) detecting, at a second detection position (E2), a light component (LS) of the incident light (L) scattered in the dialysate flow (DS), and generating a second signal (S2) which represents the intensity of the detected scattered light component (LS); d) generating a detection signal (Z) based on the generated first signal (S1) and the generated second signal (S2); e) emitting ultraviolet light (U), wherein the ultraviolet light (U) is injected into the dialysate flow (DS) and radiates through the dialysate flow (DS); f) detecting at a first detection position (E1) the ultraviolet light component (UT) of the incident ultraviolet light (U) transmitted through the dialysate flow (DS), and generating a third signal (S3) representing the intensity of the detected transmitted ultraviolet light component (UT); g) detecting, at a second detection position (E2), ultraviolet light (U) radiating through the dialysate flow (DS), and generating a fourth signal (S4), the fourth signal representing the intensity of the detected ultraviolet light (U) radiating through; h) determining a Kt / V value (K) based on the generated third signal (S3) and the generated fourth signal (S4).

2. The method according to claim 1, in, The detection signal (Z) is generated if the time profile of the first signal (S1) is opposite to the time profile of the second signal (S2).

3. The method according to claim 1 or 2, in, The second detection location (E2) is shielded from ultraviolet light (U) incident on the dialysate flow (DS).

4. The method according to claim 1 or 2, in, The light (L) and the ultraviolet light (U) are alternately injected into the dialysate flow (DS), wherein the first signal (S1) and the third signal (S3) are alternately generated by means of a first detector (9a) arranged at the first detection position (E1), and the second signal (S2) and the fourth signal (S4) are alternately generated by means of a second detector (10a) arranged at the second detection position (E2).

5. The method according to claim 1 or 2, in, The light (L) and the ultraviolet light (U) are irradiated into the dialysate flow (DS) at an alternating frequency of 1 kHz, wherein the first signal (S1) and the third signal (S3) are generated alternately with the aid of a first detector (9a) arranged at the first detection position (E1), and the second signal (S2) and the fourth signal (S4) are generated alternately with the aid of a second detector (10a) arranged at the second detection position (E2).

6. A detection device (2, 2a) for carrying out the method according to any one of the preceding claims, the detection device comprising: at least one light source (8) which is designed to emit light (L) into the dialysate flow (DS); - a first detector (9, 9a) arranged at a first detection position (E1), in, the first detector (9, 9a) being configured to detect a light component (LT) of the incident light (L) which is transmitted through the dialysate flow (DS) and to generate a first signal (S1) which represents the intensity of the detected transmitted light component (LT); a second detector (10, 10a) arranged at a second detection position (E2) different from the first detection position (E1), wherein the second detector (10, 10a) is designed to detect a light component (LS) of the incident light (L) scattered in the dialysate flow (DS) and to generate a second signal (S2) representing the intensity of the detected scattered light component (LS); - an evaluation unit (11, 11a) which is designed to generate a detection signal (Z) as a function of the first signal (S1) and the second signal (S2); and - comprises an ultraviolet light source (13) which is designed to inject ultraviolet light (U) into the dialysate flow (DS) and to radiate the ultraviolet light (U) through the dialysate flow (DS); wherein the first detector (9a) is designed to detect the UV light component (UT) of the incident UV light (U) which is transmitted through the dialysate flow (DS) and to generate a third signal (S3) which represents the intensity of the detected transmitted UV light component (UT); wherein the second detector (10a) is configured to detect ultraviolet light (U) radiating through the dialysate flow (DS) and to generate a fourth signal (S4), the fourth signal representing the intensity of the detected ultraviolet light (U) radiating through; - and wherein the evaluation unit (11a) is designed to determine a Kt / V value (K) based on the generated third signal (S3) and the generated fourth signal (S4).

7. The detection device (2, 2a) according to claim 6, It is characterized in that The evaluation unit (11, 11a) is designed to generate the detection signal (Z) as a function of a time profile of the first signal (S1) and a time profile of the second signal (S2).

8. The detection device (2, 2a) according to claim 6 or 7, It is characterized in that The light source (8) is arranged on a first side of a light-transmissive fluid guiding channel (7), the fluid guiding channel being configured to fluidly guide the dialysate flow (DS) along its longitudinal direction, the first detector (9, 9a) being arranged on a second side of the fluid guiding channel (7) spaced apart from the light source (8) in an incident direction (R1) of the light (L), the second side being opposite to the first side transversely to the longitudinal direction of the fluid guiding channel (7), and the second detector (10, 10a) being arranged on the second side of the fluid guiding channel (7) and spaced apart from the first detector (9, 9a) perpendicularly to its longitudinal direction.

9. The detection device (2, 2a) according to claim 8, It is characterized in that The second detector (10, 10a) is arranged at an angle of between 5° and 30° to the incident direction (R1) of the light.

10. The detection device (2a) according to claim 8, It is characterized in that The ultraviolet light source (13) is arranged on a first side of the fluid guiding channel (7).

11. The detection device (2a) according to claim 6 or 7, It is characterized in that A shielding element (14) is provided, by means of which the second detector (10a) is shielded from ultraviolet light (U) incident on the dialysate flow (DS).

12. The detection device (2a) according to claim 6 or 7, It is characterized in that A control unit (12a) is provided and is configured to alternately control the light source (8) and the ultraviolet light source (13).

13. The detection device (2, 2a) according to claim 11, It is characterized in that A housing (15) is provided, in which at least the light source (8), the first detector (9, 9a) and the second detector (10, 10a) are accommodated.

14. The detection device (2a) according to claim 13, It is characterized in that The ultraviolet light source (13) and / or the shielding element (14) are accommodated in the housing (15).

15. The detection device (2, 2a) according to claim 8, It is characterized in that The second detector (10, 10a) is arranged at an angle between 18° and 22° to the incident direction (R1) of the light.

16. The detection device (2a) according to claim 6 or 7, It is characterized in that A control unit (12a) is provided and is configured to alternately control the light source and the ultraviolet light source at an alternating frequency of 1 kHz.

17. A dialyzer (1) comprising a dialyzer (3) and a detection device (2, 2a) according to any one of claims 6 to 16, which is arranged on the outlet side of the dialyzer (3).

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