Device, system and method for detecting blood clots

Abstract

The aim of the invention is to enable detecting blood clots in an extracorporeal blood circuit. This aim is achieved by a device for detecting blood clots in an extracorporeal blood circuit, which device optionally comprises: an actuator which can produce an adjustable constriction in the extracorporeal blood circuit by reducing the cross-section of a portion of a blood line; at least one sensor which measures at least one parameter which is related to a property of the fluid in the extracorporeal blood circuit; and a control device which is configured to analyze a measurement signal from the at least one sensor and to enable, on the basis of this analysis of the parameter measured by the sensor, to detect a blood clot passing through the constriction and / or a blood clot getting stuck in the constriction.

Description

[0001] Device, system and method for detecting blood clots

[0002] The invention relates to the field of extracorporeal blood circulation.

[0003] The present invention relates to a device for detecting a blood clot in an extracorporeal blood circuit.

[0004] Extracorporeal blood circuits are used in various therapeutic applications for medical treatments or, for example, for blood plasma donation. In extracorporeal blood circuits, blood can experience environmental conditions that differ considerably from those within the body's own bloodstream. Extravascular blood clots can form in extracorporeal blood circuits. Extravascular means that the clot is not located in the body's own blood vessel. A blood clot within a body's own blood vessel is called a thrombus. Blood clots are clumps of blood, consisting of erythrocytes, leukocytes, and platelets, which have formed due to the onset of blood clotting. Above a certain size, blood clots can trigger negative health consequences if they enter the human bloodstream.

[0005] It is therefore an object of the present invention to provide a device, a system and a method for detecting blood clots in an extracorporeal blood circuit.

[0006] Brief description of the invention

[0007] The object is achieved by a device according to the invention for detecting blood clots in an extracorporeal blood circuit, connectable to an extracorporeal blood circuit having an adjustable constriction on a blood line, comprising: at least one sensor which detects at least one parameter which is related to a property of the fluid in the extracorporeal circuit, and a control device which is configured such that a measurement signal from the at least one sensor is evaluated, and that on the basis of this evaluation of the parameter measured by the sensor, the passage of a blood clot through the constriction and / or the getting stuck of a blood clot in the constriction can be detected, wherein the device is set up such that it can detect blood clots at an adjustable constriction which has been adjusted by constricting a blood tube with an actuator or a mechanical clamp.

[0008] One advantage of this device is that it allows for reliable, non-invasive detection of blood clots. The device according to the invention can detect not only the passage of a blood clot through the constriction, but also the partial blockage of the constriction by a blood clot that becomes lodged in the constriction.

[0009] The device according to the invention is intended and also configured to be attached to an extracorporeal blood circuit or to exist as part of an extracorporeal blood circuit system. Typically, an extracorporeal blood circuit comprises blood lines or line sections that are created, for example, using a tubing set. A blood line or blood tube for an extracorporeal blood circuit is therefore generally elastic. According to the invention, the actuator of the device presented here can create an adjustable constriction in the extracorporeal blood circuit by reducing the cross-sectional area of ​​a section of a blood line. The reduction in the cross-section of a section of a blood line is preferably achieved by compressing the blood line, i.e., an elastic deformation.Accordingly, the deformation is reversible, and when the actuator releases the blood line, it will return to the shape it had before the constriction was created. Due to hygiene requirements, blood lines, blood tubing, and tubing sets for extracorporeal blood circulation are generally intended for single use only and are disposed of after the first use. A blood treatment machine and other medical devices for use with an extracorporeal blood circuit, on the other hand, are usually used for hundreds or thousands of treatments. For blood treatment with an extracorporeal blood circuit, a combination of a reusable treatment machine and a single-use blood tubing is typically used.The device presented here for detecting blood clots is intended for multiple uses and can be part of a treatment machine. However, it can also be designed as a device separate from a treatment machine. In the context of the present application, a constriction means a section of line where the line cross-section is smaller than the rest of the line. The device presented here or a system based thereon as well as the method presented here relate to an adjustable constriction which can be created or is created in an extracorporeal blood circuit. In general, an adjustable constriction means on the one hand that the constriction can be "added" to a certain extent, i.e. can be formed by the activation of an actuator.On the other hand, the term “adjustable constriction” also means that the width – i.e. the cross-section remaining after constriction – can generally take on different values. This applies to the various embodiments. The invention relates to the detection of a blood clot passing through a constriction in an extracorporeal blood circuit. This means that the constriction can be designed in such a way that the blood circulation is not interrupted by the adjustable constriction. The adjustable constriction within the meaning of the invention can therefore be a line section that has a smaller cross-section than the surrounding line, but the line is not completely clamped off. At the adjustable constriction within the meaning of the invention, the blood line cannot be tight or closed when the adjustable constriction is adjusted. Rather, a fluid can flow through the adjustable constriction within the meaning of the invention.For example, a line section of a blood tubing set that is completely clamped off by a closed safety clamp is completely sealed / impermeable to a fluid in an extracorporeal blood circuit. This makes it clear that the latter example is clearly not an adjustable constriction within the meaning of the invention. A valve in the extracorporeal blood circuit that is completely closed is also not an adjustable constriction within the context of the invention. A mechanical means that forms an adjustable constriction on a section of a blood line within the meaning of the invention can, so to speak, be in a partially open position with regard to the cross-section of the section of the blood line in the mechanical means.Partially open means that the line section is reduced by the mechanical means compared to a section without a constriction, but at the same time is not completely compressed, so that a fluid can still flow through the constriction. Mechanical means can be an actuator, e.g., an electrically controlled linear actuator, or an electrical or electromagnetic safety clamp, or even a manually operated hose clamp. In the context of the invention, all of these means reduce a hose cross-section by compressing, thus creating a half-open position. The manually operated hose clamp can also be sold as a disposable part for single use, integrated into an article such as a blood tubing set.

[0010] The detection of blood clots in the context of the invention can serve to increase patient safety. In optional developments, a protective measure can be initiated upon detection of a blood clot. Such protective measures can include, for example, closing a safety hose clamp, stopping a blood pump, generally interrupting the flow in the extracorporeal blood circuit, or even issuing an alarm or notifying patients and / or medical personnel.

[0011] With regard to the invention, when reference is made to the detection of the passage of a blood clot through a constriction, this generally means, alternatively or additionally, the detection of a blood clot becoming stuck in this constriction.

[0012] Furthermore, the object is achieved by a method according to the invention for monitoring an extracorporeal blood circuit for detecting a blood clot in the extracorporeal blood circuit with at least the steps:

[0013] Creating a constriction in the bloodstream, in a section of a blood tube, with an actuator or with a mechanical means for manually creating a constriction,

[0014] Measuring at least one parameter that is related to a property of the fluid in the line section with the constriction with a sensor, evaluating the measurement data of the sensor to detect the passage of a blood clot through the constriction and / or the getting stuck of a blood clot in the constriction with a control device.

[0015] A synonym for "creating a constriction" can be understood as "creating a constriction" in the bloodstream. The constriction is created using an actuator. The bloodstream is often formed using an elastic blood tube. In this case, the constriction can be considered a temporary constriction, as it is created by the actuator and can be eliminated again by the actuator and by resetting the blood tube. One advantage of this procedure is that blood clots can be reliably detected non-invasively.

[0016] In the context of the present disclosure, creating a constriction in the blood circuit primarily means creating a constriction in a section of a blood tube which forms at least part of the extracorporeal blood circuit, with an actuator or with a mechanical means for manually creating a constriction, for example by making the cross-section of the blood tube in the constriction smaller than that of the blood tube outside the constriction.

[0017] To serve the above-mentioned purpose of increasing patient safety, the detection of blood clots in the extracorporeal blood circuit can preferably be carried out at a distance from the patient access point such that a safety measure can be taken. A constriction directly at the point where the patient's blood is returned, i.e. a cannula, would therefore be disadvantageous for this purpose: If a clot is detected as it passes through the cannula from the extracorporeal blood circuit into the patient's bloodstream, it cannot be prevented from entering the patient's bloodstream, for example, by stopping the flow in the extracorporeal blood circuit. This can be due to the inertia of the system, which can lead to a time delay in stopping the blood flow and / or alarm processing, meaning that a clot could still reach the patient despite being detected.But there are other reasons why a cannula is not an adjustable constriction in the context of the present application. Firstly, the constriction is not adjustable, but fixed—as a component of the extracorporeal blood circuit. The constriction of a cannula cannot be created / generated, unlike in the context of the present application. Secondly, the width of the cannula is not necessarily suitable for ensuring reliable clot detection. The sensitivity of clot detection depends on the width of the constriction, and other factors such as flow, pressure, and viscosity also play a role.

[0018] The device according to the invention for detecting blood clots is designed to detect not only the passage of a blood clot, but also the partial or complete blockage of the constriction by a blood clot. The method according to the invention also allows for the partial or complete blockage of the constriction by a blood clot. Instead of blockage, one can also speak of "getting stuck." Detecting the passage of a blood clot is the focus of this application.

[0019] The present invention relates to a device for detecting blood clots in an extracorporeal blood circuit. The device comprises a control unit configured to detect a blood clot at an adjustable constriction in a blood circuit by a sensor that detects at least one parameter related to a property of the fluid in the extracorporeal circuit. The control unit is configured to evaluate a measurement signal from the at least one sensor, and based on this evaluation of the parameter measured by the sensor, the passage of a blood clot through the constriction can be detected.

[0020] The present invention further relates to a method for monitoring an extracorporeal blood circuit for detecting a blood clot in the extracorporeal blood circuit, comprising at least the steps:

[0021] Creating a constriction in the bloodstream with an actuator or with a mechanical means for manually creating a constriction,

[0022] Measuring at least one parameter related to a property of the fluid in the pipe section with the constriction with a sensor,

[0023] Evaluating the sensor's measurement data to detect the passage of a blood clot through the constriction or the jamming of a blood clot in the constriction.

[0024] This means that an adjustable bottleneck is created and maintained for at least the duration of the measurement. This can be viewed as an implicit step.

[0025] For methods and devices, the measurement to detect a clot at the constriction is carried out over a minimum predetermined period of time by not varying the adjustable constriction. The width is therefore maintained for this period. In certain embodiments of the inventive methods and devices, the adjustable constriction is set and maintained after manufacture for at least a predetermined period of time, for example one second, so that a measurement can be carried out. Other time periods down to a few tens of milliseconds or up to double-digit seconds or even continuously for several minutes, e.g. 15 minutes, are conceivable. The short measurements can advantageously be carried out intermittently in order to disrupt the process as little as possible. The long measurements are advantageous for certain operating states or modes of blood treatment so that, if necessary,An entire operating phase, such as closed-loop reinfusion, can be completely monitored. This also makes it clear that the adjustable constriction does not refer to an infinitesimal intermediate state that occurs when, for example, a hose clamp closes in an emergency and differs in width for fractions of a second during the closing process. This unplanned coincidence is not what is meant.

[0026] The device according to the invention can have an actuator for producing the clot or can be designed without an actuator. If it is designed without the actuator, it is configured to detect blood clots at a manually created constriction during operation. This constriction can be brought about, for example, by applying a mechanical means for creating a constriction to a blood tube or blood line. In a key development, the control unit is also configured to switch, upon user input, to the operating mode for detecting blood clots or to switch to an operating mode without detecting blood clots, or alternatively, to detect, based on other parameters of an extracorporeal blood treatment, when a mode for detecting blood clots should be activated or deactivated, and to independently switch between an operating mode with and without detecting blood clots.This detection can be performed, for example, by detecting the reverse running of a blood pump of a blood treatment device or by detecting increased pressure in the blood tube caused by adjusting the constriction. Both detections (direction of rotation of a blood pump, establishment of a higher base pressure in the blood tube) can be combined. The device according to the invention can be a component of a blood treatment device or a separate device connectable to a blood treatment device. Furthermore, a system according to the invention is disclosed, which comprises a device for detecting blood clots, a blood tube or a blood line or a blood tube set, which are configured for connection to a patient and / or a blood treatment device.A further development of the system comprises, in addition to the detection device and the blood tube, a mechanical means for creating a constriction in a blood circuit. According to one aspect of the invention, a system for use with a device or method for detecting a blood clot at a constriction in an extracorporeal blood circuit is disclosed, comprising a blood tube or a blood line or a blood tubing set configured to create an extracorporeal blood circuit and a mechanical means for creating an adjustable constriction in a line section of the blood tube or the blood line or the blood tubing set.In one embodiment of the invention, a system is formed from a blood treatment machine and a device for detecting blood clots and a blood tube or a blood line or a blood tubing set, as well as a mechanical means for creating a constriction in a line section. The blood tubing set, on the one hand, and the device for detecting blood clots, on the other hand, which can be part of a blood treatment machine or separate from it, together form—like a plug and socket—in some embodiments, for example, the pairing of consumable and evaluation device for detecting blood clots, which can optionally be carried out using a method according to the invention, because the device, blood tubing set, and systems comprising the device and / or blood tubing set and method are all aspects of this invention.Some further developments and embodiments of aspects of the invention, methods, devices, and systems are discussed below. Unless technically contradictory, the further developments, embodiments, and aspects described below always refer to both devices and methods, as well as concepts encompassing these, such as systems.

[0027] In a further development of the device according to the invention for detecting blood clots in an extracorporeal blood circuit, the sensor is a flow sensor that measures the current flow rate of the fluid, or a pressure sensor that measures the current pressure of the fluid. These two sensor types particularly advantageously enable robust detection of blood clots. A further development of the device according to the invention for detecting blood clots in an extracorporeal blood circuit has at least both a flow sensor and at least one pressure sensor. Furthermore, in this further development, the control unit of the device is configured such that it uses the measured values ​​from the pressure sensor and flow sensor together to detect blood clots. By jointly evaluating measured values ​​of pressure and flow, the sensitivity of the detection of blood clots can be particularly advantageously increased.

[0028] An embodiment of the device according to the invention for detecting blood clots in an extracorporeal blood circuit comprises an actuator that can create an adjustable constriction in the extracorporeal blood circuit by reducing the cross-section of a section of a blood line. This particularly advantageously creates the possibility for the device to create the constriction required for detection without user intervention.

[0029] A further development of the device according to the invention for detecting blood clots in an extracorporeal blood circuit with an actuator is designed as a hose clamp or as a component of a hose clamp into which a medical hose can be inserted.

[0030] Tube clamps are widely used in many medical devices, for example as a safety system to prevent blood loss from the patient in the event of a malfunction (e.g. power failure) or handling error or accident (e.g. unnoticed slipping out of a cannula). Such tube clamps are usually designed so that a blood tube can be inserted into a defined receptacle and the clamp is held open during normal operation. In the event of a power failure, the clamp closes in a fraction of a second, for example through spring preload or magnetic preload. The design of the device according to the invention as a tube clamp or part of a tube clamp offers the advantages of increased cost-effectiveness because elements of an existing clamp are also used in the context of the invention. On the other hand, the solution is also very compact. In addition, safety aspects can be increased.

[0031] In a further development of the device according to the invention for detecting blood clots in an extracorporeal blood circuit, which is designed as a hose clamp or as a component of a hose clamp into which a medical tube can be inserted, the actuator can assume at least three different positions. These positions are: a closed position, in which the extracorporeal blood circuit has no free line cross-section at one point, i.e., it is blocked or the tube is clamped off by the clamp; an open position, in which the extracorporeal blood circuit has no constriction at the actuator; and a third, partially open position, which lies between the closed and open positions, in which a preset constriction for detecting blood clots can be created on an inserted tube.In the first position, the tube is not permeable, but completely compressed / clamped / squashed. In this case, the effective cross-section for fluid transport in the constriction is zero. In the second position, the tube's cross-section is not impaired by the clamp, i.e., it is at its maximum. In the third position, a defined constriction is created in the tube by the clamp being half-open. This defined constriction is designed for the inventive detection of blood clots. The particular advantage of a clamp with three positions is that it fulfills the same function as a conventional tube clamp, but in the half-open position can form an inventive device for detecting blood clots.

[0032] In a further development of the device according to the invention for detecting blood clots in an extracorporeal blood circuit, wherein the actuator is designed as a hose clamp or as a component of a hose clamp into which a medical hose can be inserted, the actuator can assume at least three different positions. These positions are: a closed position, in which the extracorporeal blood circuit has no free line cross-section at one point, i.e., it is blocked or the hose is clamped off by the clamp; an open position, in which the extracorporeal blood circuit has no constriction at the actuator; and a third, partially open position, which lies between the closed and open positions, in which a preset constriction for detecting blood clots can be created on an inserted hose.In the first position, the tube is not permeable, but completely compressed / clamped / squashed. In this case, the effective cross-section for fluid transport in the constriction is zero. In the second position, the tube's cross-section is not impaired by the clamp, i.e., it is at its maximum. In the third position, a defined constriction is created in the tube by the clamp being half-open. This defined constriction is designed for the inventive detection of blood clots. The particular advantage of a clamp with three positions is that it fulfills the same function as a conventional tube clamp, but in the half-open position can form an inventive device for detecting blood clots.

[0033] In a further development of the device according to the invention for detecting blood clots in an extracorporeal blood circuit, which is designed as a hose clamp or as a component of a hose clamp into which a medical tube can be inserted, and wherein the actuator can assume at least three different positions, the hose clamp has so-called polymagnets. Polymagnets have a plurality of magnetized regions such that the clamp has at least three different positions. Polymagnets are disc-shaped magnets made of a ferromagnetic material that can be variably magnetized in small sections perpendicular to the disc surface by applying an external magnetic field. By using such very finely adjustable magnets, different clamp positions can be adapted particularly advantageously for the application according to the invention.

[0034] In a further development of the device according to the invention for detecting blood clots in an extracorporeal blood circuit, wherein the actuator is designed as a hose clamp or as a component of a hose clamp into which a medical tube can be inserted, and wherein the actuator can assume at least three different positions, the hose clamp has so-called polymagnets. Polymagnets have a plurality of magnetized regions such that the clamp has at least three different positions. Polymagnets are disc-shaped magnets made of a ferromagnetic material that can be variably magnetized in small, finely divided portions perpendicular to the disc surface by applying an external magnetic field. By using such very finely adjustable magnets, different clamp positions can be adapted particularly advantageously for the application according to the invention.

[0035] In a further development of the device according to the invention for detecting blood clots in an extracorporeal blood circuit, which is designed as a hose clamp or as a component of a hose clamp into which a medical tube can be inserted, a spacer can be arranged between clamping elements of the clamp in order to thus realize the partially open clamp position at the constriction. One might think that this arrangement contradicts the actual intended use of a hose clamp as a safety device. However, on the one hand, it is conceivable to design a hose clamp such that the clamp can still close completely and the spacer only partially closes the clamp. On the other hand, it is conceivable to convert a hose clamp to detect blood clots by using the specific spacer and configuring the control unit for detecting blood clots based on sensor data.This makes it particularly advantageous to manufacture a device according to the invention with reduced effort by modifying existing machine elements, thus shortening development time. Another advantage is the high degree of commonality with existing technology. A clamp converted to create a constriction for the detection of blood clots cannot simply be used as a conventional safety clamp. In some applications, such as hemodialysis, a clamp converted in this way would then be considered in addition to the clamps required for safety purposes. The device designed according to this aspect only optionally has an actuator for creating the constriction. Variants do not have an actuator: In this case, a constriction can be created solely by means of a spacer. Other variants have an actuator, so that a constriction can be created either with the actuator or with the spacer.In this case, it is again possible that a different width of the constriction can be achieved with the spacer than with the actuator. This advantageously allows the constriction to be adapted cost-effectively to individual parameters of a blood treatment. It is conceivable that a converted clamp includes a spacer that is arranged on the clamp in a foldable or otherwise movable manner, so that it can be inserted into the clamp as needed to create a constriction. Alternatively, it is conceivable to provide a clamp and a separate spacer as a kit. As a further development, it is conceivable to provide a kit with several different or even identical spacers.

[0036] In a further development of the device according to the invention for detecting blood clots in an extracorporeal blood circuit, wherein the actuator is designed as a hose clamp or as a component of a hose clamp into which a medical tube can be inserted, a spacer can be arranged between clamping elements of the clamp in order to thus realize the partially open clamp position at the constriction. One might think that this arrangement contradicts the actual intended use of a hose clamp as a safety device. However, it is conceivable, on the one hand, to design a hose clamp such that the clamp can still close completely, while the spacer only partially closes the clamp.On the other hand, it is conceivable to convert a hose clamp to detect blood clots by using the specific spacer and configuring the control unit for detecting blood clots based on sensor data. This makes it particularly advantageous to manufacture a device according to the invention with reduced effort by modifying existing machine elements and to shorten development time. Another advantage is the high degree of common parts with existing technology. A clamp converted to create a constriction for detecting blood clots cannot simply be used as a conventional safety clamp. In some applications, such as hemodialysis, a clamp converted in this way would then be considered in addition to the clamps required for safety. The device designed according to this aspect only optionally has an actuator for creating the constriction.Variants do not have an actuator: In this case, a constriction can be created using a spacer alone. Other variants have an actuator, so that a constriction can be created either with the actuator or with the spacer. In this case, it is again possible for a different width of the constriction to be created with the spacer than with the actuator. This advantageously allows the constriction to be adapted cost-effectively to individual parameters of a blood treatment. It is conceivable for a converted clamp to include a spacer which is arranged on the clamp in a foldable or otherwise movable manner so that it can be inserted into the clamp as needed to create a constriction. Alternatively, it is conceivable to provide a clamp and a separate spacer as a kit. As a further development of this, it is conceivable to provide a kit with several different or identical spacers.

[0037] In a further development of the device according to the invention for detecting blood clots in an extracorporeal blood circuit, the actuator and the control unit are configured such that the device can assume at least two different operating states, in each of which the actuator forms the constriction, wherein the predetermined width of the constriction differs in the different operating states. Here, the device thus has at least two different predetermined operating states with a predetermined width at the constriction, wherein the predetermined width is such that blood flow through the constriction does not completely cease, i.e., there is no completely occluding constriction. This makes it possible to select the width of the constriction such that a parameter of the extracorporeal blood circuit is taken into account in order to achieve the highest available sensitivity or reliability for detecting blood clots.One parameter can be the volume flow rate of the blood. In one embodiment, for example, a smaller width of the constriction is selected if a lower volume flow rate is present. One parameter can be the diameter or wall thickness of the blood line / blood tube. One parameter can be the viscosity or hematocrit of the blood or the temporal progress of the treatment. One parameter can be a set flow rate of a blood pump. Another parameter can be the pressure in the blood tube when the constriction is still open. One parameter can be a value that is calculated from the pressure in the tube and the volume flow rate in the tube. In addition to the pressure parameter, a pressure increase when creating the adjustable constriction with a known blood volume flow can be a further parameter. This can advantageously compensate for the influence of a patient connector such as a cannula on the pressure measurement, for example.

[0038] In the two different predetermined operating states with different predetermined widths at the constriction, in both cases the blood tube is not completely clamped off in the area of ​​the adjustable constriction, but the blood in the extracorporeal blood circuit can flow through the constriction.

[0039] In a further development of the device according to the invention for detecting blood clots in an extracorporeal blood circuit, which is designed as a hose clamp or as a component of a hose clamp into which a medical tube can be inserted, and in which the actuator can assume at least three different positions, the actuator can assume at least one further partially open fourth position for setting predetermined constrictions, wherein the predetermined width of the constriction varies in the various partially open positions. The advantages from the further development described in the previous paragraph also apply here. All aspects and embodiments of the present invention have in common that an adjustable constriction is formed for the detection of blood clots, wherein an actuator or a mechanical means assumes a partially open position.Partially open also refers to the cross-section of the section of the blood line located at the adjustable constriction: Here, the free cross-section of the blood line is reduced compared to the relaxed blood line, as might be found in sections before and / or after the adjustable constriction. The free cross-section is reduced only to the extent that fluid flow through the constriction remains possible.

[0040] In a further development of the device according to the invention for detecting blood clots in an extracorporeal blood circuit, the actuator and the control unit are configured such that the device can assume at least two different operating states, in each of which the actuator forms the constriction, wherein the predetermined width of the constriction differs in the various operating states. The control unit is configured to select the width of the constriction according to a predetermined scheme and to adjust it on the actuator for detecting blood clots, taking into account a parameter of the extracorporeal blood circuit. This additional configuration of the control unit, which adjusts the width of the constriction taking into account a parameter, advantageously enables automation of the device.Furthermore, the ability to detect blood clots is advantageously improved if the device can select the setting most suitable for detection.

[0041] In a further development of the device according to the invention for detecting blood clots in an extracorporeal blood circuit, which is designed as a hose clamp or as a component of a hose clamp into which a medical tube can be inserted, and in which the actuator can assume at least three different positions as well as at least one further partially open, fourth position for adjusting predetermined constrictions, wherein the predetermined width of the constriction differs in the various partially open positions, the control unit is configured to select the clamp position according to a predetermined scheme for operation for detecting blood clots, taking into account a parameter of the extracorporeal blood circuit, and to adjust it on the actuator. The advantages mentioned in the previous paragraph for the exemplary embodiment there also apply here.In a further development of the device according to the invention for detecting blood clots in an extracorporeal blood circuit, the width of the constriction is variable, and the control unit is configured to adjust the constriction for operation to detect blood clots, taking into account a parameter of the extracorporeal blood circuit, such that the sensitivity and / or robustness of the detection is optimized. An advantage of this further development is that the sensitivity or robustness of the detection can be even better than for embodiments in which one or more predetermined widths of the constriction are specified. For example, it is conceivable that a parameter of the extracorporeal blood circuit lies midway between two values ​​which, according to the scheme, require a certain width of the constriction for optimal results.Here, with the variable constriction of this embodiment, an individual width of the constriction can be assumed, thus improving detection compared to a set of rigid widths. In a further embodiment, the control unit is configured to variably select an optimized width of the constriction for specific, previously known blood tubes or blood tubing sets. Alternatively or additionally, the control unit can be configured to adapt the width of the constriction to different tubing sets or blood tubes or blood lines or blood tubing sets. One advantage would be that blood clots can be easily detected in the same device even with different blood tubes - e.g. for the treatment of adults or designed for the treatment of children, which have significantly thinner tubes (smaller inner diameter and / or smaller wall thickness of the blood tube / blood line).For this purpose, the control unit can be configured, for example, to process a bloodline parameter such as wall thickness or inner diameter as an input value for the adjusted constriction setting. Depending on the embodiment, the control unit can be configured to receive such a value, for example, manually entered or transmitted from another device or other components of a device, for example, if the device is part of an extracorporeal blood treatment machine.

[0042] In a further development of the device according to the invention for detecting blood clots in an extracorporeal blood circuit, a roller pump is the actuator and the constriction is created by arranging a movable mechanical means for creating the constriction on or adjacent to the roller pump in such a way that in the event of reverse running, the pump moves the mechanical means and thus creates the constriction.

[0043] In a further development of the device according to the invention for detecting blood clots in an extracorporeal blood circuit, the width of the constriction is variable, and the control unit is configured to adjust the constriction for operation to detect blood clots, taking into account a parameter of the extracorporeal blood circuit, such that the sensitivity and / or robustness of the detection is optimized. The control unit is configured to calculate the optimal width of the constriction during medical treatment with the extracorporeal blood circuit, depending on a parameter of the extracorporeal blood circuit and / or a parameter of the treatment, and to adjust it with the actuator. This advantageously enables automated, individually improved detection of blood clots.By automating the device, human errors are reduced and the capacity of medical personnel is less strained.

[0044] One embodiment of the invention relates to a blood tubing set configured for use with a device presented here for detecting blood clots in an extracorporeal blood circuit or with a method presented here for detecting blood clots in an extracorporeal blood circuit. The blood tubing set comprises a blood tubing or a blood line and a mechanical means, in particular a mechanical clamp, for adjusting a constriction on a line section of the blood tubing or blood line. This advantageously provides the user with a blood tubing set suitable for detecting blood clots.

[0045] One aspect of the present invention relates to an extracorporeal blood treatment device comprising a device according to the invention for detecting a blood clot, a tube clamp and / or a means for issuing an alarm and / or a blood pump, wherein the control unit of the blood treatment device is configured to close the tube clamp and / or issue an alarm and / or stop the blood pump when the device for detecting blood clots detects a blood clot. In other words, according to this aspect, an extracorporeal blood treatment device according to the invention is equipped with a device according to the invention for detecting a blood clot. In addition, the extracorporeal blood treatment device comprises one or more of the active components from this list: tube clamp, means for issuing an alarm, blood pump.The control unit is configured such that, upon detection of a blood clot, at least one component is activated in response to the detection of a blood clot. This particularly advantageously enables a direct control response to the detection of a blood clot. Various variants of this are included. For example, a variant of the invention is included in which the extracorporeal blood treatment device comprises a device according to the invention for detecting blood clots and a tube clamp, wherein the control unit is configured to close the tube clamp when the device detects a blood clot.Alternatively or additionally, a variant of the invention is included, for example, in which the extracorporeal blood treatment device comprises a device according to the invention for detecting blood clots and a means for issuing an alarm, wherein the control unit is configured to issue an alarm when the device detects a blood clot. Alternatively or additionally, a variant of the invention is included, for example, in which the extracorporeal blood treatment device comprises a device according to the invention for detecting blood clots and a blood pump, wherein the control unit is configured to stop the blood pump when the device detects a blood clot. These three variants can also be combined as desired.For example, in a variant with a tube clamp and blood pump, the control unit can be configured so that when a blood clot is detected, both the tube clamp is closed and the blood pump is stopped. Furthermore, for example, in a variant with a blood pump and means for issuing an alarm, the control unit can be configured so that when a blood clot is detected, the blood pump is stopped and an alarm is also issued. Furthermore, in a variant with means for issuing an alarm and a tube clamp, the control unit can be configured so that when a blood clot is detected, an alarm is issued and the tube clamp is also closed. Or, for example, in a variant that has means for issuing an alarm, a tube clamp and a blood pump, the control unit can be configured to issue an alarm, close the tube clamp and stop the blood pump when a blood clot is detected.Further variants are conceivable. For example, variants with multiple active means, i.e., multiple blood pumps, multiple peristaltic pumps, or multiple means for issuing an alarm, are also conceivable. The control unit can then be configured to perform the aforementioned actions on one or more of the active means upon detection of a blood clot. For example, one or more blood pumps can be stopped, one or more peristaltic clamps can be closed, or an alarm can be issued on one or more means for issuing an alarm. It is also conceivable to issue multiple alarms using one means for issuing an alarm.

[0046] According to one aspect of the invention, the aforementioned extracorporeal blood treatment device comprising a device according to the invention for detecting a blood clot is a hemodialysis machine. The device according to the invention for detecting blood clots can advantageously be used in conjunction with a hemodialysis machine or as a component thereof. This results in particular synergies, because some elements of a conventional hemodialysis machine can also be used as elements of the device for detecting blood clots, or vice versa; elements of the device can also expand the hemodialysis machine beyond the detection of blood clots. A pressure sensor or blood volume flow sensor, for example, can be such an element. Furthermore, the invention is also particularly advantageous in the context of hemodialysis because there is an existing interest in detecting blood clots.

[0047] According to one aspect of the invention, a system for extracorporeal blood treatment of a patient comprises an extracorporeal blood treatment machine, and the extracorporeal blood treatment machine comprises a device according to the invention for detecting a blood clot in an extracorporeal blood circuit. The system also comprises a blood tube. The device for detecting blood clots is arranged on a section of the blood line that is at least 30 cm upstream of the patient's access. This advantageously makes it possible to detect blood clots by the device at a considerable distance from the patient. This distance corresponds to slightly more than what is covered in a period of 1.5 s at a blood volume flow of 200 ml / min with a tube inner diameter of 4.5 mm. This time period is sufficient for a safety tube clamp to react.In one embodiment, the section of the blood line with the constriction is arranged depending on the blood volume flow rate intended for an individual treatment and taking into account the inner diameter of the blood tube to be used such that blood in measuring mode for detecting a blood clot would reach the patient at the earliest 1.5 s after passing the constriction. This embodiment is initially an alternative to the embodiment in which the distance is at least 30 cm. Since in this embodiment the distance is calculated using a formula, it is also possible that the formula results in a distance of 30 cm or more and thus the two embodiments have an overlapping parameter range. The distance x (Q, D, T) in [cm] as a function of blood volume flow rate Q in [ml / s=cm. 3 / s], inner tube diameter D in [cm] and the desired time T in [s] between detection of the clot and cessation of blood flow in the extracorporeal blood circuit, can be calculated as follows:

[0048] With Q=200 cm we get 3 / s; D = 4.5 mm; T = 1.5 s, a value of approximately 18.9 cm for the distance x. With the 30 cm specified above, the distance is definitely farther than the blood volume that would be transported from the constriction under these conditions within 1.5 seconds. An arrangement of the adjustable constriction at a distance from the patient access according to the above-mentioned formula is conceivable for all aspects of the invention.

[0049] According to a further aspect of the invention, the distance of the adjustable constriction to the patient access can alternatively be determined according to the following formula. The device for detecting blood clots is arranged at a section of the blood line, which is determined as a function of the blood volume flow rate and the tube diameter as follows:

[0050] Q 4.5 [mm] x = 30 cm * - * -

[0051] 200 L ÄmtnJ] D

[0052] Where x is the distance in cm, Q is the blood volume flow rate in [ml / min], and D in [mm] is the free inner diameter, the usual general diameter of the blood tubing where no adjustable constriction is formed. This advantageously makes it possible to select a minimum value for the distance of the adjustable constriction, determined by treatment parameters, while still enabling safe stopping of blood flow in such a way that a clot detected in the adjustable constriction remains in the extracorporeal circuit. With a flow rate of 300 ml / min and an inner diameter of the relaxed blood tubing, this results in a distance of 45 cm. An arrangement of the adjustable constriction at a distance from the patient access according to the above formula is conceivable for all aspects of the invention.

[0053] An embodiment of a method presented here therefore additionally includes the step of determining the aforementioned distance. This step precedes the creation of the adjustable constriction. The spatial distance also advantageously enables a longer reaction time or time to detect a blood clot and process the detection. As a further development, a larger safety distance is conceivable, e.g., corresponding to 2 s or 3 s, or a fixed distance such as 50 cm or 100 cm.

[0054] In a further development of the method according to the invention, the method for monitoring an extracorporeal blood circuit for detecting a blood clot is expanded to also include an aspect of controlling the extracorporeal blood treatment device. In addition to the steps for detecting a blood clot, the method for controlling an extracorporeal blood treatment device comprises the step of closing a tube clamp and / or issuing an alarm and / or stopping a blood pump if the passage of a blood clot through the constriction is detected. The above-mentioned aspects of the device according to the invention, which include closing a tube clamp and / or issuing an alarm and / or stopping a blood pump if the passage of a blood clot through the constriction or the jamming of a blood clot in the constriction is detected, also apply to sub-forms of the method.

[0055] One purpose of the alternatives of the aforementioned further development, which are directed at closing a tube clamp and / or stopping a blood pump, is to ensure that when a blood clot is detected at the adjustable constriction, the clot does not reach the patient. It is then an implicit requirement that the adjustable constriction is positioned at a distance from both patient-side ends of the blood line such that when the passage of a clot through the adjustable constriction is detected, there is still sufficient reaction time so that when the tube clamp is closed and / or the blood pump is stopped, the blood volume containing the detected clot does not reach the patient. This means:the distance - along a blood line - must be chosen at least so that there is enough time for the control of the extracorporeal blood circuit and the reaction of the actuators - also taking into account the inertia of the respective system - to prevent the blood volume with the detected clot from being transported to the patient.

[0056] The terms blood clot detection and blood clot detection can be used synonymously.

[0057] According to one aspect, the present device for detecting blood clots in an extracorporeal blood circuit is connected to an extracorporeal blood treatment machine or a component of an extracorporeal blood treatment device, wherein the extracorporeal blood treatment device is configured to infuse the blood in the extracorporeal blood circuit back to the patient by closed-loop reinfusion upon completion of the extracorporeal blood treatment. This particularly advantageously makes it possible to increase the safety of the reinfusion, the blood treatment, and the extracorporeal blood treatment device. For example, the extracorporeal blood treatment machine in this example can be a hemodialysis machine or a machine for therapeutic apheresis.

[0058] According to one aspect, the present device for detecting blood clots in an extracorporeal blood circuit as a safety system for extracorporeal blood circuits is designed such that the device can be subsequently added to an existing extracorporeal blood treatment device or an existing extracorporeal blood circuit (so-called retrofitting). The device is designed as a retrofit kit such that, for example, depending on requirements, it can establish a wired or wireless data connection with a blood treatment machine or operate without a data connection; it has an independent electrical power supply (for example, via a potential-free isolation transformer from the power grid or via a rechargeable battery) or is powered by a blood treatment machine; and it can simply be clamped to a blood tube with a clip.In a completely independent variant, the device optionally has its own display means, its own means for issuing an alarm, and / or a transmission device for transmitting measured values ​​and / or alarm signals. The methods according to the invention can also be considered applicable to this aspect.

[0059] According to one aspect of the present invention, the control device is configured to detect whether the actuator is in an open state or whether the actuator forms a constriction in the extracorporeal blood circuit.

[0060] According to a further development of this aforementioned aspect, the control device is configured to carry out the evaluation of sensor signals for detecting a blood clot only when the actuator forms a constriction.

[0061] According to a further development of the aforementioned aspect, the control unit is additionally configured to detect a quantitative parameter relating to the size of the constriction. Examples of such parameters are the distance between two clamping jaws, for example of a hose clamp, the current cross-section of a fluid conductor in the constriction, or parameters relating to the actuator. Parameters relating to the actuator can also be parameters that are not directly explicitly a parameter of the size of the constriction itself, but are unambiguously related to the size of the constriction and thus allow conclusions to be drawn about the size of the constriction. Such parameters can be the position of a servo motor, the clamp position, the position of a linear motor, or the angular position, for example, of a rotatably mounted actuator magnet.

[0062] Other parameters of the extracorporeal blood circuit used to determine the optimal width of the constriction include the set blood flow rate, the temporal progress of the treatment, the wall thickness of the tube / bloodline / blood line, the position of a roller on a tube roller pump (the latter, for example, to take pressure pulsation in roller pumps into account when detecting blood clots), and the viscosity or hematocrit of the blood. Another parameter can be the pressure in the blood line when the constriction is still open. A parameter can be a value calculated from the pressure in the tube and the volume flow rate in the tube. In addition to the pressure parameter, a pressure increase when creating the adjustable constriction with a known blood volume flow can be a further parameter. This can advantageously compensate for the influence of a patient connector such as a cannula on the pressure measurement, for example.

[0063] In an advantageous development, the device according to the invention is used in conjunction with a pump capable of generating a temporally constant blood flow—for example, an impeller pump. Such pumps generate a uniform blood flow, whereas roller pumps, diaphragm pumps, and syringe pumps, for example, generate oscillating blood flows. A temporally constant blood flow particularly advantageously enables a further increased sensitivity of the device in the inventive detection of blood clots. This is because if the underlying, undisturbed blood flow is constant, deviations from it can be detected particularly easily.

[0064] Many medical devices use hose clamps to cut off the flow through a hose with a flexible wall. These clamps are used in many medical applications and are often designed so that a hose is inserted into an open clamp. These clamps are generally used as a safety device, particularly for blood-carrying hoses. They are intended to ensure that, for example, the blood flow can be interrupted in the event of an emergency. To do this, the clamps must have an open and a closed position and be switchable between the two operating states. For this purpose, such clamps often have a clamping means, a means for mechanical resetting (e.g. a spring), and an electrically controlled holding element.The return mechanism provides force to close the clamp when the holding element is de-energized, thereby clamping the blood line and interrupting a blood flow. In some areas of medicine or medical technology, such tube clamps are mandatory to ensure patient safety. While a continuously pumping pump such as an impeller pump, a gear pump, or a combination of several syringe pumps would be advantageous, use with cyclically operating pumps such as roller pumps or syringe pumps is also conceivable.Advantageous for a device or method with a cyclically operating pump for pumping fluid in the extracorporeal blood circuit is a configuration with a pressure sensor, which is arranged to determine the current pressure curve over time in the fluid pumped by the pump in a current pumping cycle, and to store a reference pressure curve in a memory, wherein the memory can belong to a device according to the invention or to a higher-level blood treatment device. The device according to the invention or, if applicable, a higher-level blood treatment device then has an evaluation unit, which determines pressure deviations by comparing a pressure curve from the current pumping cycle with the reference pressure curve and detecting pressure deviations based on deviations. The reference pressure curve can be obtained by recording the pressure curve over time, e.g.from one or more pump cycles preceding the current pump cycle, or from historical data or average values. For greater accuracy, the reference pressure curve is preferably based on one or more pump cycles of the same pump that occurred immediately or at least a few pump cycles earlier than the current pump cycle.

[0065] According to a development of the present invention, a device according to the invention is implemented in such a way that a tube clamp prescribed for patient safety is extended such that it has an actuator that can create an adjustable constriction. The tube clamp is thereby extended such that, in addition to the two usual operating states "fully open", which is adopted during normal blood treatment, and "fully closed", which is adopted, for example, in emergency situations such as a power failure, it can adopt a third operating state "adjusted constriction for the detection of blood clots", which is neither fully open nor fully closed. This particularly advantageously enables the integration of the device for detecting blood clots into a device that is already present in many applications, such as the blood tube clamp.This enables particularly compact, resource-saving, and reliable integration. According to a further development of the just described development with integration of the device according to the invention, the hose clamp is further developed compared to known hose clamps in such a way that it comprises two disk-shaped permanent magnets with more than two magnetic poles, which are generated by magnetization perpendicular to the surface area of ​​the disk, e.g., with an electromagnetic coil arrangement in the manner of a hard disk write head (so-called Polymagnets®). The realization of hose clamps with polymagnetizable magnets particularly advantageously enables an efficient, compact, energy-saving device. This is because the various operating states can be configured by adjusting the magnetic zones so that only a small amount of energy is required to remain in the respective operating state.

[0066] In a particularly advantageous development of a system according to the invention, such a hose clamp as described above is used in a system together with a blood pump with continuous flow, in particular an impeller pump. This particularly advantageously enables a further increased sensitivity of the device in the inventive detection of blood clots. A corresponding advantage is also obtained when pumps or combinations of pumps and / or other elements such as valves and throttles or branches are interconnected in such a way that a continuous blood flow results. Furthermore, a corresponding advantage also applies when blood is transported in an extracorporeal blood circuit by a pump that is not arranged in the blood circuit itself but continuously pumps - such as a gear pump - and a medium that mediates the pump propulsion - such as dialysate.

[0067] In the context of this invention, an adjustable constriction means that the constriction is not fixed and unchangeable in the bloodstream, but can be adjusted by means of an actuator. In the simplest case, an adjustable constriction means that an actuator of the device can create and remove the constriction, or that an adjustable constriction can be created or removed on a blood tubing set by applying, for example, a mechanical means to constrict the cross-section of the blood tubing. In other words, an adjustable constriction does not mean a constriction that remains unchanged in an extracorporeal bloodstream throughout its period of use (comprising treatment as well as preparation and follow-up to the treatment). It therefore does not mean a constriction such as that used by a cannula for vascular access to connect the extracorporeal bloodstream to, for example, a patient.Such cannulas generally have a smaller cross-section than a blood line, which typically makes up a significant part of an extracorporeal blood circuit. Also not included are other elements that are fixed and invariably arranged in an extracorporeal blood circuit, such as Luer connectors or time-invariable constrictions in the flow cross-section, as found in cassette elements or at transitions between different line sections, e.g. due to design reasons. If the actuator is not currently creating the constriction, the point in the blood circuit where the actuator can create a constriction is not constricted by the actuator. In other words, in the simplest case, the constriction can be activated by the actuator, or it can also not exist. This ensures that a constriction is only created when blood clot detection is actively carried out.If no blood clot detection occurs, the actuator does not reduce the cross-section of the bloodstream to the constriction required for the measurement. The width of the constriction can preferably be predetermined and adjusted to the inventive blood clot detection.

[0068] A blood clot detection arrangement in the context of this application may comprise the following subgroups:

[0069] An extracorporeal blood circuit with an adjustable constriction on a section of the tube,

[0070] A device for detecting blood clots comprising a sensor that detects at least one parameter related to a property of the fluid in the extracorporeal blood circuit, and wherein an open fluidic connection exists between the tube portion of the adjustable constriction and the tube portion of the sensor, so that the sensor can detect a change in the measurement parameter resulting from the passage of a clot through the adjustable constriction.

[0071] Conversely, if a complete occlusion were to exist in the extracorporeal blood circuit between the sensor and the adjustable constriction, this would not be in accordance with the teaching of the present application, because then the change in the measurement parameter caused by the passage of a clot through the adjustable constriction could not be detected by the sensor.

[0072] The subassemblies or components from the previous paragraph can be sold as separate products. A device for detecting a blood clot according to the invention can be sold separately and designed as a retrofit kit for extracorporeal blood circulation devices or can be sold as components of such devices. Such devices can, in particular, be extracorporeal blood treatment devices. The creation of an adjustable constriction for detecting blood clots can be achieved by means of an actuator of the device—for example, an electromechanical tube clamp or a linear actuator. In these embodiments, the blood tubing set to be used can be a blood tubing set conventional for the specific application, e.g., in dialysis, therapeutic apheresis, or heart and lung support. The actuator of the device forms the constriction on a conventional blood tubing set.Alternatively, an adjustable constriction for blood clot detection can be created by applying a manual clamp. The clamp can be sold individually or as part of a blood tubing set for treatment. Unlike common manual blood tubing clamps, this clamp must be designed to create the adjustable constriction on the blood tubing for blood clot detection as a partially open constriction, i.e., so that blood circulation is not stopped but can continue. Such a clamp can be implemented as part of a single-use blood tubing set or as a separate product.

[0073] According to a preferred embodiment of the device or method according to the invention, the adjustable constriction and a pressure sensor can be arranged close to each other, i.e., a maximum of a few centimeters apart, along the course of a blood line. This particularly advantageously results in a more direct measurement for detecting blood clots, which is also less susceptible to interference than at a greater distance.

[0074] According to a preferred embodiment, the device and method according to the invention are adapted such that the constriction can be implemented on a blood line for extracorporeal blood treatment with an inner diameter between 3 mm and 15 mm in the relaxed state. The free cross-sectional area in the adjustable constriction preferably corresponds to 1% to 99% of the cross-sectional area in the relaxed state. More preferably, the area corresponds to 10% to 90% of the cross-sectional area in the relaxed state. In any case, the width of the adjustable constriction is selected such that it enables detection of a clot, preferably improved detection.

[0075] According to one aspect of the invention, the width of the adjustable constriction created by the actuator of the present device on the bloodstream is predetermined and adapted to the present detection of blood clots.

[0076] According to a further aspect of the method according to the invention for monitoring an extracorporeal blood circuit to detect a blood clot in the extracorporeal blood circuit, the method steps of creating a constriction in the blood circuit with an actuator, measuring at least one parameter that is related to a property of the fluid in the line section with the constriction with a sensor, and evaluating the measurement data of the sensor to detect the passage of a blood clot through the constriction during a reinfusion process after a hemodialysis treatment are used, in which the patient's blood is returned simultaneously via two patient connectors, e.g. via both an arterial and a venous cannula, during the reinfusion. In this case, for example, no clot catcher can be arranged along the blood line in one of the two branches.

[0077] In one embodiment, the method is extended by a sequence of method steps for individually adjusting the width of the adjustable constriction as follows:

[0078] - A defined blood volume flow is set

[0079] - The adjustable bottleneck is created

[0080] - The pressure and / or other parameters of the blood at the sensor are changed by creating the constriction - Adjusting the width of the constriction until a predetermined setpoint of the pressure and / or other parameters is reached

[0081] - Detection of clots

[0082] Analogously, a control unit of a device with an actuator for generating a variable constriction can advantageously be configured to adapt the width of the constriction.

[0083] This makes it possible to achieve the optimal measuring range of a parameter for detecting blood clots - such as pressure or flow and / or other parameters.

[0084] A blood volume flow rate sensor may also be abbreviated to flow meter or flow sensor or volume flow sensor or volume flow rate sensor.

[0085] Blood tubing and blood line can be used synonymously. Blood tubing set and blood tubing kit can be used synonymously. A blood tubing set comprises at least one blood tubing and can optionally have branches. A section of a blood tubing can be synonymous with a segment of a blood tubing. An adjustable constriction according to the teaching of the present application is located on a section of a blood tubing through which blood flows during operation of an extracorporeal blood circuit. A segment of a blood tubing can also have special properties such as material properties, material composition, and tubing cross-section.

[0086] One aspect of the present invention relates to a system for use with a device or a method for detecting a blood clot at a constriction in an extracorporeal blood circuit, comprising a blood tube or a blood line or a blood tubing set configured to establish an extracorporeal blood circuit and a mechanical means for establishing an adjustable constriction on a line section of the blood tube or the blood line or the blood tubing set. The blood tube or the blood line or the blood tubing set is configured to establish an extracorporeal blood circuit and for connection to a human. For this purpose, the blood tube or the blood line or the blood tubing set can have connecting means. The blood tube or the blood line or the blood tubing set can be designed for single use.The blood tube or blood line or blood tubing set may be designed in such a way that it can be manufactured with an extracorporeal blood circuit using an extracorporeal blood treatment device.

[0087] A preferred embodiment of the present invention relates to a manual mechanical tube clamp for creating an adjustable constriction on a section of a blood tube of an extracorporeal blood circuit for the detection of blood clots in the extracorporeal blood circuit. The clamp is designed such that it can assume and maintain a partially open position. In the partially open position, the clamp can partially compress a section of a blood tube, thereby forming a constriction on the blood tube and allowing the blood tube to continue to be permeable to a fluid at the constriction. Known clamps do not allow for a partially open position, as required for the detection of blood clots.One advantage of a manual mechanical tube clamp for creating an adjustable constriction for the detection of blood clots is that it allows blood clots to be detected without the actuators of a treatment machine, and that a standard blood tubing set can also be used. The hygiene required in the medical field can be achieved, for example, by making the clamp made of plastic and intended for single use, sterilizing and sterile packaging, or by making the clamp autoclavable and made of medical-grade steel. "Assuming position" means that the clamp remains in the partially open state, i.e., is locked, until it is released again. This means a defined state, a clamping position, that the clamp can assume.This does not mean that, for example, a standard pair of household scissors cannot only be fully opened and fully closed, with a partial opening in between: that would not correspond to a defined state, a specific clamping position, as is meant here.

[0088] One aspect of the present invention relates to a blood tubing set for extracorporeal blood treatment for the detection of blood clots in an extracorporeal blood circuit, comprising a manual mechanical tube clamp as described in the previous paragraph and a blood tube with an arterial end for connection to a patient access. This particularly advantageously ensures that the tube and clamp are coordinated in such a way that an adjustable constriction within the meaning of the present teaching can be formed with the clamp on the tube.

[0089] According to a further development of the blood tubing set described in the previous paragraph for the detection of blood clots in an extracorporeal blood circuit, which has a manual mechanical tube clamp that can assume a partially open position, the blood tubing set additionally comprises at least one mechanical manual tube clamp that completely blocks the tube in a clamping position, whereby this additional tube clamp does not have a partially open position. This refers to a conventional manual tube clamp with which a blood tube can be completely blocked by pressing. Advantageously, the blood tubing set therefore comprises at least two different clamps for different tasks. Embodiments of this

[0090] However, a further development can also include two, three, or more standard manual hose clamps that completely block the hose in one clamping position. In a further development, the clamps are provided with a marking to reduce the risk of confusion.

[0091] According to a further development of a blood tubing set for the detection of blood clots in an extracorporeal blood circuit, which has a manual mechanical tube clamp that can assume a partially open position, as described in one of the two previous paragraphs, once with and once without a further additional mechanical clamp that can completely interrupt the blood flow by completely clamping the tube in a clamping position, the blood tubing set is designed such that with the clamp, which can assume a partially open position, the adjustable constriction can be formed on a section of the blood line in one of the following areas by arranging the clamp and by transferring the clamp to the partially open state:

[0092] [Alternative AA] Between the arterial end of the blood line, i.e. the access to the patient (H), and a pump tube segment, which is a section of a blood tube that can be inserted into a blood pump, wherein the blood tube set comprises the pump tube segment; or [Alternative BB] Between a manual mechanical tube clamp, which does not have a partially open position, but in its clamping position completely compresses the blood tube, and a pump tube segment, which is a section of a blood tube that can be inserted into a blood pump, wherein the blood tube set comprises the pump tube segment; or

[0093] [Alternative CC] between a manual mechanical tube clamp, which does not have a partially open position, but in its clamping position completely compresses the blood tube, and a device for arterial pressure measurement of the blood tubing set, wherein the blood tubing set has the device for arterial pressure measurement; or

[0094] [Alternative DD] between a device for arterial pressure measurement of the blood tubing set and a pump tubing segment, which is a section of a blood tubing that can be inserted into a blood pump, wherein the blood tubing set comprises the pump tubing segment, wherein - if there are several blood pumps and / or pump tubing segments - the pump tubing segment is meant which is closest to the arterial end of the blood line, wherein the blood tubing set comprises the device for arterial pressure measurement and the pump tubing segment; or

[0095] [Alternative EE] between a fluidic interface configured for administering an infusion and a pump tube segment of the blood tubing set, which is a section of a blood tube that can be inserted into a blood pump, wherein the blood tubing set has the interface for administering an infusion and a blood pump and the pump tube segment; or

[0096] [Alternative FF] at least 30 cm upstream of the arterial end of the blood line, i.e. the patient access (H); or

[0097] [Alternative GG] at least at a distance x upstream of the arterial end of the blood line, i.e. the patient access (H), according to the following formula for

[0098] Determination of the distance or [Alternative HH] at least at a distance x upstream of the arterial end of the blood line, i.e. the patient access (H), according to the following formula for Calculation of the distance x upstream of the patient access (H).

[0099] A particular advantage of alternatives AA to HH in this further development is that the blood tubing set and clamp are designed in such a way that the adjustable constriction can be positioned at locations favorable for the detection of blood clots. Alternatives AA to HH are designed in such a way that they are not mutually exclusive: Depending on the parameter values ​​and configuration of the blood tubing set, etc., it is possible that the calculations for alternatives GG and HH will produce the same value or a value corresponding to alternative FF. This means that two or three of these alternatives could be met at the same time. Furthermore, for a given tubing set, one of alternatives AA to EE could be met at the same time, meaning that one or more of alternatives FF to HH and at least one of alternatives AA to EE can be met at the same time.In known tubing sets, the area of ​​alternative AA can include the areas of alternatives BB to EE, the area of ​​alternative BB can include the area of ​​alternative CG and alternative EE. The area of ​​alternative CC can include the area of ​​alternative EE. Known tubing sets can be designed such that the area of ​​alternative DD and the area of ​​alternative CC do not overlap. Known tubing sets can be designed such that the area of ​​alternative DD and the area of ​​alternative EE overlap. The term tubing set can be used synonymously with the term blood tubing set. For alternatives EE to HH, it can be particularly advantageous that the distance between the adjustable constriction and the patient access allows sufficient reaction time for the system, thus preventing a detected blood clot from being transported to the patient.

[0100] One aspect of the present invention relates to an extracorporeal blood treatment device comprising a device according to the invention for detecting a blood clot, an electromagnetic safety hose clamp for squeezing a blood tube in the event of an imminent risk and / or a means for issuing an alarm and / or a blood pump, wherein the control unit of the blood treatment device is configured to close the safety hose clamp and / or issue an alarm and / or stop the blood pump when the device for detecting blood clots detects a blood clot.In other words, according to this aspect, an extracorporeal blood treatment device according to the invention is equipped with a device according to the invention for detecting a blood clot, and the extracorporeal blood treatment device additionally comprises one or more of the active components from this list: electromagnetic safety hose clamp, means for issuing an alarm, blood pump. The statements elsewhere in this document apply where an extracorporeal blood treatment device according to the invention with active components such as a hose clamp, means for issuing an alarm, or blood pump are mentioned. Since this is an active component of a device, "hose clamp" does not mean a manual mechanical hose clamp, but rather an electrical, electromagnetic, or otherwise actuated hose clamp.

[0101] One aspect of the invention relates to a system for extracorporeal blood treatment of a patient, comprising an extracorporeal blood treatment device with a device according to the invention for detecting blood clots in an extracorporeal blood circuit. The extracorporeal blood treatment device additionally has an electromagnetic safety hose clamp for squeezing a blood tube in the event of an imminent risk and / or a means for issuing an alarm and / or a blood pump, wherein the control unit of the blood treatment device is configured to close the safety hose clamp and / or issue an alarm and / or stop the blood pump when the device for detecting blood clots detects a blood clot. An extracorporeal blood treatment device generally has a control unit.It is possible for the blood clot detection device and the extracorporeal blood treatment device to have separate control units. However, it is also possible for both functionalities to be combined in one control unit. In this case, the control unit of the extracorporeal blood treatment device would also have the functionality of the control unit of the blood clot detection device. The system further comprises a blood tubing set. In this embodiment of the invention, the blood clot detection device is arranged on a section of the blood line that is at least 30 cm upstream from the patient access or that is calculated according to one of the two following alternative formulas for determining the distance x:

[0102] This advantageously allows the device to detect blood clots at a significant distance from the patient. The statements described elsewhere in this document regarding the positioning of the adjustable constriction at a specific distance also apply to this embodiment, unless contradictory.

[0103] One aspect of the invention relates to a system for extracorporeal blood treatment of a patient, comprising an extracorporeal blood treatment device with a device according to the invention for detecting blood clots in an extracorporeal blood circuit. The extracorporeal blood treatment device additionally has an electromagnetic safety hose clamp for squeezing a blood tube in the event of an imminent risk and / or a means for issuing an alarm and / or a blood pump, wherein the control unit of the blood treatment device is configured to close the safety hose clamp and / or issue an alarm and / or stop the blood pump when the device for detecting blood clots detects a blood clot. An extracorporeal blood treatment device generally has a control unit.It is possible for the device for detecting blood clots and the extracorporeal blood treatment device to have separate control units. However, it is also possible for both functionalities to be combined in one control unit. In this case, the control unit of the extracorporeal blood treatment device would also have the functionality of the control unit of the device for detecting blood clots. The system further comprises a blood tubing set. In the system according to this embodiment, the blood tubing set and the blood treatment device are arranged relative to one another such that an adjustable constriction for detecting blood clots is formed on a section of the blood line in one of the following areas by means of an actuator or a mechanical clamp:

[0104] [Alternative 21AA] between the arterial end of the blood line, i.e. the access to the patient, and a pump tube segment, which is a section of a blood tube that can be inserted into a blood pump, wherein the blood tube set comprises the pump tube segment;

[0105] [Alternative 21 BB] between a manual mechanical tube clamp, which does not have a partially open position, but in its clamping position completely compresses the blood tube, and a pump tube segment, which is a section of a blood tube that can be inserted into a blood pump, wherein the blood tube set has the pump tube segment;

[0106] [Alternative 21 CC] between a manual mechanical tube clamp, which does not have a partially open position but completely compresses the blood tube in its clamping position, and a device for measuring the arterial pressure of the blood tube set, wherein the blood tube set has the device for measuring the arterial pressure;

[0107] [Alternative 21 DD] between a device for arterial pressure measurement of the blood tubing set and a pump tubing segment, which is a section of a blood tubing that can be inserted into a blood pump, wherein the blood tubing set comprises the pump tubing segment, wherein - if there are several blood pumps and / or pump tubing segments - the pump tubing segment is meant which is closest to the arterial end of the blood line, wherein the blood tubing set comprises the device for arterial pressure measurement and the pump tubing segment;

[0108] [Alternative 21 EE] between a fluidic interface configured for administering an infusion and a pump tube segment of the blood tubing set, which is a section of a blood tube that can be inserted into a blood pump, wherein the blood tubing set has the interface for administering an infusion and a blood pump and the pump tube segment.

[0109] The statements made above regarding the locations of the adjustable constriction, including the advantages, apply to alternatives 21 AA to 21 EE. When this document refers to "pressurizing a hose" (fully or partially), this refers to "blocking." This means that it is not important whether the adjustable constriction is created by pressing or the cross-section is reduced in some other way. Therefore, "pressurizing" can also be interpreted as "blocking." This also applies to the partially open position of an adjustable constriction.

[0110] An embodiment of the method according to the invention for monitoring an extracorporeal blood circuit for detecting a blood clot in the extracorporeal blood circuit comprises at least the following steps:

[0111] - Creating an adjustable constriction in the blood circuit by compressing a section of a blood tube, the adjustable constriction having a width such that the blood can continue to flow through the constriction, with an actuator or by adjusting or attaching a manual mechanical clamp, the manual clamp assuming a partially open position,

[0112] - measuring at least one parameter related to a property of the fluid in the pipe section with the constriction, using a sensor,

[0113] - Evaluation of the measurement data of the sensor to detect the passage of a blood clot through the constriction with a control unit.

[0114] The statements made above regarding the method according to the invention, including the advantages, apply to this embodiment of the method.

[0115] Character description

[0116] It shows:

[0117] Figure 1 is a diagram of an extracorporeal blood circuit connected to the blood circuit of a human being, with a device according to the invention;

[0118] Figure 2 two graphs of the fluid pressure and volume flow velocity on the same time axis;

[0119] Figure 3 is a diagram of an extracorporeal blood circuit configured for hemodialysis treatment, with a device according to the invention;

[0120] Figure 4 shows a modification of the diagram of an extracorporeal blood circuit which can be connected to the blood circuit of a person, with a device according to the invention as in Figure 1 but with the pump in a different position.

[0121] Figure 1 schematically shows an extracorporeal blood circuit 300 with a device 100 presented here for detecting blood clots in an extracorporeal blood circuit. In the schematic illustration, a person H is indicated on the left, to whom the extracorporeal blood circuit is connected in the example shown. The upper branch of the blood circuit 300 leads from the person H via a blood pump 10 to an adjustable constriction 20 in the blood line. The actuator D of the device can create the adjustable constriction 20 by reducing the cross-section of the blood line in a section 25.

[0122] Downstream of the constriction 20, a pressure sensor P for measuring the fluid pressure in the extracorporeal blood circuit 300 and a volume flow rate sensor Q for measuring the flow rate of the extracorporeal blood circuit 300 are arranged. In a basic variant, however, only one of these two sensors P, Q is required. The second sensor is optional. After passing the sensors, the blood flows back to the person H via the lower branch of the extracorporeal blood circuit 300. At the location of the constriction 20, there is typically an elastic blood tube. An actuator D can create a constriction itself or, as shown here, be connected to another element E, which compresses the section of the blood tube and thus forms the constriction. The constriction 20 can be adjusted using the actuator D.Shown is an exemplary structure in which a constriction 20 is formed and the blood tube is deformed accordingly at a section 25, so that the cross-section is reduced. The control unit CU of the device 100 presented here is connected to the actuator D of the adjustable constriction and the sensor(s) P, Q. The order shown here in the flow direction of pump 10, constriction 20 and sensor(s) P, Q is only an example. Arrangements in which the sensor(s) P, Q are arranged between the pump 10 and the constriction 20, or other arrangements, are also conceivable. In the embodiment shown, it may happen that a blood clot, which is transported from the blood pump P further through the extracorporeal blood circuit 300, then reaches the constriction 20. The presence of a blood clot in the constriction 20 will lead to a change in the flow Q and the pressure P.The control unit CU records the measured values ​​of the sensor(s) and can thus detect a blood clot in the constriction.

[0123] Figure 2 shows a diagram in which measurement data recorded using a device 100 according to the invention in the arrangement from Figure 1 are plotted. Two separate graphs O, U are shown in one diagram. The upper graph O shows measurement data of a volume flow rate measured with a volume flow sensor Q, and the lower graph U shows measurement data of a pressure measurement measured with a pressure sensor P. The measurement data were recorded simultaneously on the same device 100 and share a common abscissa axis on which the time "Time" is plotted in seconds s. On the ordinate axis, the two graphs have different value ranges and units: The upper graph O shows the volume flow rate "Flow" in ml / min, with many values ​​in the range of approximately 140 - 150 ml / min. The lower graph U shows the pressure relative to a reference pressure in mbar, with the values ​​initially being in the single-digit positive range and then dropping to almost approximately -20 mbar.Although the quantities plotted on the ordinate in the two different graphs differ, it is expedient to plot them on a common axis. The arrows on the left of the diagram, approximately at "Time" = 22 s on the abscissa axis, mark a brief drop a in flow and pressure caused by the passage of a blood clot through the constriction 20. The brief drop in flow and / or pressure is an example of a signature in the measurement signals by which the device 100 according to the invention detects the passage of a blood clot through the adjustable constriction 20. On the right of the diagram, approximately at "Time" = 44 s, arrows point to a further abrupt drop b in flow and pressure, whereby flow and pressure, however, remain at the low level after the drop b.This is the signature of a clot that has become trapped in the constriction 20 of a configuration with a continuously pumping pump, such as an impeller pump. In a different arrangement of the elements (pump 10, constriction 20, pressure gauge P and / or volume flow rate sensor Q), the passage of a clot through the constriction 20 can be accompanied by an increase in pressure and flow. Depending on the configuration, however, a flow value can also decrease while a pressure increases.

[0124] Figure 3 shows the device 100 according to the invention in an exemplary embodiment configured for a hemodialysis treatment with a dialyzer D in the extracorporeal blood circuit 300. On the right side of the image, an arm of a patient H with two connectors, shown as an arterial and a venous blood cannula, is indicated. During a dialysis treatment, blood flows in the lower branch from the patient H to a dialyzer DZ, first passing through an optional first flow meter Q', then the actuator D, which can create an adjustable constriction 20 on a line section 25 of the blood line, then a second flow meter Q and a pressure gauge P, as well as a blood pump 10, optionally symbolized here as a roller pump. Instead of a roller pump P, other blood pumps P, such as impeller pumps P, can also be used. During the reinfusion phase, the blood present in the extracorporeal blood circuit is reinfused into the patient.In the so-called closed-loop reinfusion, in the arrangement shown in Figure 3, blood is transported from the dialyzer DZ via the blood pump 10 and the constriction 20 back to the patient H in the lower branch. Detection of blood clots according to the invention is already possible if only one sensor, i.e., a blood volume flow rate sensor Q or a pressure gauge P, is arranged in this branch of the extracorporeal blood circuit. The other sensors are optional. However, the arrangement of both the pressure sensor P and the flow sensor Q and their combined evaluation is advantageous in that greater sensitivity can be achieved.In the arrangement of Figure 3, the passage of blood clots would have a different sign than that shown in Figure 2, depending on which of the partially optional sensors are arranged: In an embodiment according to Figure 3 with only one pressure sensor P and one volume flow rate sensor Q between the adjustable constriction 20 and the blood pump, failing signatures of blood clots would be measured as described below. During treatment operation, a blood clot in the constriction 20 would lead to a reduction in pressure and flow in the sensors. In the case of reinfusion, a clot in the constriction 20 would lead to an increase in the measured pressure and a decrease in the measured volume flow rate.Figure 4 schematically shows the extracorporeal blood circuit 300 with a device 100 presented here for detecting blood clots in an extracorporeal blood circuit, as in Figure 1, with the only difference being that the pump is arranged upstream of the sensors and the constriction. A representation analogous to the data plot in Figure 2 would have different signs in the presence of blood clots. The arrangement shown here has the pressure sensor positioned upstream of the constriction in the direction of flow. This particularly advantageously enables a high sensitivity of the pressure measurement for clots in the constriction.

Claims

Patent claims 1. A device (100) for detecting blood clots in an extracorporeal blood circuit (300), connectable to an extracorporeal blood circuit (300) having an adjustable constriction, comprising: at least one sensor (P, Q) that detects at least one parameter related to a property of the fluid in the extracorporeal blood circuit (300), a control unit (CU) configured to evaluate a measurement signal from the at least one sensor (P, Q), and to detect, based on this evaluation of the parameter measured by the sensor (P, Q), the passage of a blood clot through the constriction (20) and / or the getting stuck of a blood clot in the constriction (20), wherein the device (100) is configured to detect blood clots at an adjustable constriction, which has been adjusted by constricting a blood tube with an actuator or a mechanical clamp.

2. Device (100) according to claim 1, wherein the sensor is a flow sensor (Q) that measures the current flow rate of the liquid, or a pressure sensor (P) that measures the current pressure of the liquid.

3. Device (100) according to claim 1, comprising at least one flow sensor (Q) and at least one pressure sensor (P), wherein the control unit (CU) is configured to use the measured values ​​of at least one flow sensor (Q) and at least one pressure sensor (P) in conjunction to detect blood clots.

4. Device (100) according to one of claims 1 to 3, comprising an actuator (D) which can create an adjustable constriction (20) on the extracorporeal blood circuit by reducing the cross-section of a section of a blood line (25).

5. Device (100) according to claim 4, which is designed as a hose clamp or as a component of a hose clamp into which a medical hose can be inserted.

6. Device (100) according to claim 5, wherein the actuator (D) can assume at least three different positions, namely: a closed position in which the extracorporeal blood circuit (300) has no free line cross-section at one point, i.e. is blocked, an open position in which the extracorporeal blood circuit (300) has no constriction (20) at the actuator (D) and (c) a third, A partially open position, which lies between the closed and the open position, in which a set constriction (20) for detecting blood clots can be created on an inserted tube (25). The device (100) according to claim 6, wherein the tube clamp has so-called polymagnets, which have a plurality of magnetized regions such that the clamp has at least three different positions. The device (100) according to claim 5, wherein a spacer can be arranged between clamping elements of the clamp in order to thus realize the partially open clamp position at the constriction, and wherein the device (100) only optionally comprises an actuator (D) that can create an adjustable constriction (20) on the extracorporeal circuit.The device (100) according to any one of claims 4 to 8, wherein the actuator (D) and the control unit (CU) are configured such that the device (100) can assume at least two different operating states, in each of which the actuator (D) forms the constriction (20), wherein the predetermined width of the constriction (20) differs in the different operating states. The device (100) according to claim 9, wherein the control unit (CU) is configured to select the width of the constriction (20) according to a predetermined scheme and to adjust it on the actuator (D) in order to detect blood clots, taking into account a parameter of the extracorporeal blood circulation.The device (100) according to any one of claims 4 to 7, 9, or 10, wherein the width of the constriction (20) is variable, and the control unit (CU) is configured to adjust the constriction (20) for operation to detect blood clots, taking into account a parameter of the extracorporeal blood circuit (300), such that the sensitivity and / or robustness of the detection is optimized. The device (100) according to claim 11, wherein the control unit (CU) is configured to calculate the optimal width of the constriction (20) during a medical treatment with the extracorporeal blood circuit (300) as a function of a parameter of the extracorporeal blood circuit (300) and / or a parameter of the treatment, and to adjust it using the actuator (D).A blood tubing set adapted for use with a device according to any one of claims 1 to 3 or a method according to any one of claims 18 or 19, comprising a blood tube or blood line and a mechanical means. in particular, a mechanical clamp for adjusting a constriction on a section of the blood tube or blood line. A manual mechanical tube clamp for creating an adjustable constriction on a section of a blood tube of an extracorporeal blood circuit for detecting blood clots in the extracorporeal blood circuit, wherein the clamp is designed such that it can assume and maintain a partially open position. In the partially open position, the clamp can partially compress a section of a blood tube, thereby forming a constriction on the blood tube and allowing the blood tube to remain permeable to a fluid at the constriction. A blood tube set for extracorporeal blood treatment for detecting blood clots in an extracorporeal blood circuit, comprising a manual mechanical tube clamp according to claim 14 and a blood tube.which has an arterial end for connection to a patient access. A blood tubing set for detecting blood clots in an extracorporeal blood circuit according to claim 15, additionally comprising a mechanical manual tube clamp that completely closes the tube in a clamped position, but does not have a partially open position. A blood tubing set for detecting blood clots in an extracorporeal blood circuit according to claim 15 or 16, designed such that, with the clamp, which can assume a partially open position, the adjustable constriction can be formed at a section of the blood line in one of the following areas by arranging the clamp and by transferring the clamp to the partially open state: between the arterial end of the blood line, i.e., the access to the patient (H), and a pump tubing segment, which is a section of a blood tubing that can be inserted into a blood pump,wherein the blood tubing set comprises the pump tubing segment; or between a manual mechanical tubing clamp, which does not have a partially open position but in its clamping position completely compresses the blood tubing, and a pump tubing segment, which is a section of a blood tubing that can be inserted into a blood pump, wherein the blood tubing set comprises the pump tubing segment; or between a manual mechanical tubing clamp, which does not have a partially open position but in its clamping position compresses the blood tubing, completely presses, and a device for arterial pressure measurement of the blood tubing set, wherein the blood tubing set has the device for arterial pressure measurement; or between a device for arterial pressure measurement of the blood tubing set and a pump tubing segment, which is a section of a blood tubing that can be inserted into a blood pump, wherein the blood tubing set has the pump tubing segment, wherein - if there are several blood pumps and / or pump tubing segments - the pump tubing segment is meant which is closest to the arterial end of the blood line, wherein the blood tubing set has the device for arterial pressure measurement and the pump tubing segment;or between a fluidic interface configured for administering an infusion and a pump tube segment of the blood tubing set, which is a section of a blood tube that can be inserted into a blood pump, wherein the blood tubing set has the interface for administering an infusion and a blood pump and the pump tube segment; or at least 30 cm upstream of the arterial end of the blood line, i.e. the patient access (H); or at least at a distance x upstream of the arterial end of the blood line, i.e. the patient access (H), according to the following formula for; Determination of the distance or at least at a distance x upstream of the arterial end of the blood line, i.e. the patient access (H), according to the following formula for 200 D Determination of the distance x minupstream of the patient's access (H). Extracorporeal blood treatment device comprising: A device (100) according to one of claims 1 to 12, an electromagnetic safety hose clamp for squeezing a blood hose in case of imminent risk and / or a means for Output of an alarm and / or a blood pump (10), wherein the control device of the The blood treatment device is configured to close the safety hose clamp and / or issue an alarm and / or stop the blood pump (10) when the device (100) for detecting blood clots detects a blood clot. Extracorporeal blood treatment device according to claim 18, wherein the blood treatment device is a hemodialysis machine. A system for extracorporeal blood treatment of a patient, comprising an extracorporeal blood treatment device according to claim 18 or 19 and a blood tube, wherein the adjustable constriction for detecting blood clots (100) is formed on a section of the blood line such that the constriction is arranged at least 30 cm upstream of the patient's access (H) or such that the constriction is at least at a distance x according to one of the two following alternative formulas for determining the distance x located upstream of the patient access (H).A system for extracorporeal blood treatment of a patient, comprising an extracorporeal blood treatment device according to claim 18 or 19 and a blood tubing set, wherein the blood tubing set and the blood treatment device are arranged relative to one another in such a way that an adjustable constriction for detecting blood clots (100) is formed on a section of the blood line in one of the following areas by means of an actuator or by means of a mechanical clamp: between the arterial end of the blood line, i.e. the access to the patient (H), and a pump tubing segment, which is a section of a blood tubing that can be inserted into a blood pump, wherein the blood tubing set has the pump tubing segment; between a manual mechanical tubing clamp, which does not have a partially open position but completely compresses the blood tubing in its clamping position, and a pump tubing segment, which is a section. a blood tube that can be inserted into a blood pump, wherein the blood tube set has the pump tube segment; between a manual mechanical tube clamp, which does not have a partially open position, but rather completely compresses the blood tube in its clamping position, and a device for arterial pressure measurement of the blood tube set, wherein the blood tube set has the device for arterial pressure measurement; between a device for arterial pressure measurement of the blood tube set and a pump tube segment, which is a section of a blood tube that can be inserted into a blood pump, wherein the blood tube set has the pump tube segment, wherein - if there are several blood pumps and / or pump tube segments - the pump tube segment is meant which is closest to the arterial end of the blood line, wherein the blood tube set has the device for arterial pressure measurement and the pump tube segment;between a fluidic interface configured for administering an infusion and a pump tube segment of the blood tubing set, which is a section of a blood tube that can be inserted into a blood pump, wherein the blood tubing set has the interface for administering an infusion and a blood pump and the pump tube segment. A method for monitoring an extracorporeal blood circuit for detecting a blood clot in the extracorporeal blood circuit, comprising at least the following steps: Producing an adjustable constriction (20) on the blood circuit (300) by compressing a section of a blood tube, wherein the adjustable constriction has a width such that the blood can continue to flow through the constriction, with an actuator or by adjusting or attaching a manual mechanical clamp, wherein the manual clamp assumes a partially open position, Measuring at least one parameter related to a property of the liquid in the line section with the constriction (20) with a sensor (P, Q), Evaluation of the measurement data of the sensor (P, Q) to detect the passage of a blood clot through the constriction with a control unit. A method for controlling an extracorporeal blood treatment device comprising the method according to claim 22 and additionally the step: Closing a tube clamp and / or issuing an alarm and / or stopping a blood pump (10) when the passage of a blood clot through the constriction (20) is detected.

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