Automatic reinfusion of blood after blood treatment therapy

Abstract

The present disclosure relates to an extracorporeal blood treatment apparatus having an extracorporeal circuit, a dialyzer, a dialysate circuit and a control unit. A sensor is provided not only in the venous section but also in the arterial section of the extracorporeal circuit, which is designed to detect the hematocrit fraction in the liquid flowing through the respective section. The control unit is designed to control the reinfusion of blood in such a way that dialysate is provided from the dialysate circuit via the dialyzer membrane to the extracorporeal circuit, which, upon reinfusion, expels blood present in the extracorporeal circuit towards the patient in order to infuse the blood back to the patient via the venous section and the arterial section. Here, the reinfusion in the respective section of the extracorporeal circuit is interrupted when the hematocrit fraction is detected by the respective sensor or is calculated or predicted by the control unit on the basis of information detected by the respective sensor to be below a predetermined limit value.

Description

Technical Field

[0001] This disclosure relates to an extracorporeal blood processing device, particularly a dialysis machine, prepared or designed for the automatic re-infusion / re-delivery of blood to a patient after blood processing therapy. Furthermore, this disclosure relates to a device for automatically performing blood re-infusion after blood processing therapy. Background Technology

[0002] Following blood treatment, in which the patient's blood is cleaned outside the body using a dialyzer and dialysate flowing through it, the patient's blood, which is still in the extracorporeal circuit, such as in an arterial / venous tubing system (A / V tubing system), is reinfused into the patient. This process is called reinfusion. The patient is only completely decoupled from the extracorporeal tubing system when the blood still in the extracorporeal circuit is appropriately reinfused / re-infused into the patient.

[0003] A re-infusion method using an isotonic saline solution delivered via a bag (hereinafter referred to as a saline bag) is known from existing technology. Here, after blood treatment, the user / caregiver first decouples only the arterial end / arterial segment of the extracorporeal circuit / hose system from the patient and connects it to the saline bag. If the blood pump now present in the extracorporeal circuit rotates in the treatment direction, the blood is displaced by the saline solution and flows through the arterial segment, the dialyzer, and the venous segment of the extracorporeal circuit, and is then returned to the patient via the venous end of the extracorporeal circuit.

[0004] Furthermore, a reinfusion method via a replacement fluid port or connector is known from the prior art. Here, after blood treatment by the user, only the arterial end / segment of the extracorporeal circuit / hose system is initially decoupled from the patient and connected to the replacement fluid port or connector of the extracorporeal blood treatment device. If the blood pump rotates in the treatment direction in this case, the blood is displaced by the replacement fluid and flows through the arterial segment, dialyzer, and venous segment of the extracorporeal circuit, and is returned to the patient via the venous end of the extracorporeal circuit.

[0005] In both of the mentioned reinfusion methods, reinfusion can be interrupted by stopping the blood pump. For example, reinfusion can be interrupted in a volume-controlled manner when a predetermined volume has been infused. Furthermore, reinfusion can be interrupted in a time-controlled manner, for example, after a predetermined reinfusion time has elapsed. Additionally, in principle, a sensor designed to identify saline solution or replacement fluid can be placed at the venous end / in the venous segment. For example, as known from EP1996253B1, reinfusion can be interrupted by stopping the blood pump when the phase boundary between blood and saline solution has reached the venous end of the extracorporeal circuit.

[0006] Disadvantageously, in both of the mentioned reinfusion methods, a replacement fluid port must be present on the dialysis machine or an external saline bag must be used. In other words, machines without an integrated replacement fluid connector must forcibly use a saline bag for reinfusion, which is associated with high costs. Furthermore, the user must intervene at least twice in the mentioned reinfusion methods. Specifically, in these methods, the patient is first decoupled from the artery (user action), then reinfusion is performed, and finally, the patient is decoupled from the vein (user action).

[0007] Ideally, user interaction or intervention should be minimized. Furthermore, it is advantageous that the reinfusion can be performed without an external saline bag or replacement fluid port. Particularly desirable is automated reinfusion of blood after blood treatment, eliminating the need for manual intervention by the user between the end of blood treatment and the start of reinfusion.

[0008] Here, as is generally known in the prior art, the reinfusion of blood is automatically and directly controlled after blood treatment, such that dialysate is supplied from the dialysate circuit via the dialyzer membrane to the extracorporeal circuit, which, upon reinfusion, displaces blood present in the extracorporeal circuit toward the patient to return the blood to the patient. For this purpose, reference is made, by way of example only, to EP2950841B1, EP2583702B1, EP3476414A1, or EP1684825B1. Here, volume-controlled interruption of reinfusion is known from EP2950841B1 and EP2583702B1. In EP2583702B1, volume-controlled termination / interruption of reinfusion begins when the provided color sensor identifies the dialysate. Furthermore, as known from EP3476414A1, reinfusion is automatically interrupted when the provided blood sensor detects a blood concentration below a maximum permissible threshold in the arterial segment.

[0009] In the prior art, there is potential for improvement in principle regarding appropriate interruption criteria for discontinuing reinfusion. In particular, the prior art does not provide appropriate interruption of reinfusion when blood is returned to the patient not only via the venous segment but also via the arterial segment. Here, the prior art, in particular, does not consider the absence of a phase boundary between blood and the reinfusion fluid (dialysis fluid) during reinfusion; rather, blood and reinfusion fluid / dialysis fluid are mixed. Furthermore, the prior art cannot satisfactorily prevent air from entering the patient during reinfusion. Summary of the Invention

[0010] In this context, the objective of this disclosure is to avoid or at least mitigate the disadvantages of the prior art. Specifically, automatic initiation and implementation of reinfusion should be provided after the end of dialysis treatment, allowing for patient decoupling only after reinfusion requires user intervention. In other words, caregiver interaction / intervention should be limited to a minimum. Therefore, reinfusion should ideally be performed without an external saline bag or replacement fluid port. In particular, dialysate should be used as the reinfusion fluid, supplied to the extracorporeal circuit via the dialyzer membrane from the dialysate circuit. The objective of this disclosure is also to provide improved control over the interruption of reinfusion as blood is returned to the patient via the arterial and venous segments of the extracorporeal circuit, and to prevent air ingress into the patient during reinfusion.

[0011] This disclosure provides an extracorporeal blood treatment device according to the present invention and a method for automatically performing blood retransfusion after blood treatment according to the present invention.

[0012] This disclosure first relates to an extracorporeal blood treatment device comprising: an extracorporeal circuit including an arterial segment and a venous segment, a dialyzer, and a dialysate circuit, wherein the extracorporeal circuit and the dialysate circuit are separated from each other via a membrane disposed in the dialyzer; a first sensor is disposed in the venous segment, the first sensor being designed to detect the hematocrit fraction of the fluid flowing through the venous segment; a second sensor is disposed in the arterial segment, the second sensor being designed to detect the hematocrit fraction of the fluid flowing through the arterial segment; and the extracorporeal blood treatment device further includes a control unit designed to control (automatically / directly after blood treatment) the re-infusion of blood such that dialysate is supplied from the dialysate circuit through the membrane of the dialyzer to the extracorporeal circuit, the dialysate, upon re-infusion, displacing blood present in the extracorporeal circuit toward the patient, so as to return blood to the patient via the venous segment and the arterial segment. The control unit is designed to interrupt reinfusion via the venous segment when the hematocrit fraction is detected by the first sensor or calculated or predicted by the control unit based on information detected by the first sensor, and to interrupt reinfusion via the arterial segment when the hematocrit fraction is detected by the second sensor or calculated or predicted by the control unit based on information detected by the second sensor, and to interrupt reinfusion via the arterial segment.

[0013] In the dialysate circuit of the extracorporeal blood processing device, it is preferable to provide not only a dialyzer inlet valve but also a dialyzer outlet valve. The dialyzer inlet valve is preferably located upstream of the dialyzer at the dialysate inlet. The dialyzer outlet valve is preferably located downstream of the dialyzer at the dialysate outlet. Advantageously, a flow pump inlet is arranged in the dialysate inlet (upstream of the dialyzer inlet valve). More preferably, a flow pump outlet is arranged in the dialysate outlet (downstream of the dialyzer outlet valve). The flow pump inlet and / or flow pump outlet are preferably configured as gear pumps.

[0014] According to this disclosure, reinfusion is preferably initiated after the completion of blood treatment by overpressure in the dialysate circuit or on the dialysate side of the dialyzer. Due to the overpressure, the dialysate passes through the dialyzer membrane. According to this disclosure, this dialysate is used as the reinfusion fluid. The overpressure on the dialysate side is preferably established by appropriate control / regulation by a control unit. In particular, the flow pump inlet can be manipulated to pump the dialysate into the dialyzer. Preferably, the flow pump outlet is stopped. When the dialyzer outlet valve is closed, a suitable pressure (transmembrane pressure) is applied to the dialyzer membrane through the dialysate. This pressure should not exceed the maximum permissible transmembrane pressure of the dialyzer used. Furthermore, it is preferable to select the pressure (transmembrane pressure) such that the transfer of dialysate is achieved at a defined flow rate (flow rate / volume flow rate). In particular, the defined flow rate can be set to between 50 ml / min and 200 ml / min, for example, 100 ml / min, depending on the dialyzer used.

[0015] Preferably, an (arterial) blood pump (preferably configured as a roller pump to deliver fluid / liquid by squeezing a tubing) is provided in the arterial segment of the extracorporeal circuit. This (arterial) blood pump is designed to change its rotational direction, and the control unit manipulates the arterial blood pump during reinfusion via the arterial segment to rotate it opposite to the treatment direction. Alternatively, the blood pump can also be designed to switch from a closed to an open state (e.g., via a retractable roller). In this case, the blood pump is not necessarily designed to change its rotational direction to enable arterial reinfusion. The arterial reinfusion can therefore also be performed opposite to the treatment direction without rotating the blood pump.

[0016] However, in order to return blood to the patient not only via the arterial segment of the extracorporeal circuit but also via the venous segment, it is preferable to drive the arterial blood pump at a constant delivery rate to generate a constant flow rate opposite to the direction of treatment. This means that the arterial flow pump preferably delivers fluid from the dialyzer toward the arterial end of the extracorporeal circuit.

[0017] For example, if the delivery rate of the arterial flow pump is set such that a flow rate opposite to the treatment direction is generated in the arterial segment, corresponding to half the flow rate transferred via the dialyzer membrane (e.g., 50 ml / min, if the defined flow rate via the dialyzer membrane is 100 ml / min), then the flow rate in the venous segment, directed towards the vein in the treatment direction, automatically corresponds to the arterial flow rate. This is because the flow rate introduced into the venous segment is the difference between the flow rate transferred via the dialyzer membrane and the flow rate delivered by the arterial blood pump. Finally, when the hose clamps (arterial and venous hose clamps) present in the extracorporeal circuit are opened, blood not only in the arterial segment of the extracorporeal circuit but also in the venous segment can be expelled towards the patient via the transferred dialysate.

[0018] According to the preferred / described embodiment, the control unit is thus configured to perform reinfusion via the venous segment and reinfusion via the arterial segment in parallel / simultaneously.

[0019] According to another or alternative preferred embodiment, the control unit may also be designed to perform reinfusion via the venous segment and reinfusion via the arterial segment serially / continuously / sequentially. Here, in principle, reinfusion via the venous segment can be performed first, followed by reinfusion via the arterial segment. Alternatively, in principle, reinfusion via the arterial segment can be performed exactly first, followed by reinfusion via the venous segment.

[0020] For example, serial blood return or reinfusion can be implemented such that blood is first returned to the patient from the venous blood tubing side / venous segment, and then only blood from the arterial blood tubing side / arterial segment is reinfused. Here, it is preferable (as in parallel reinfusion) to initiate reinfusion after the blood treatment is completed by overpressure on the dialysate side of the dialyzer. By said overpressure, the dialysate passes through the dialyzer membrane and is used as the reinfusion fluid. If the arterial blood pump now stops and the venous tubing clamp opens, the blood in the venous tubing segment / segment is expelled toward the patient by the transferred dialysate. After the venous reinfusion is interrupted, the reinfusion direction is advantageously reversed. In particular, the venous tubing clamp is then closed, and the arterial tubing clamp is opened (if previously closed) or remains open. The arterial blood pump is now advantageously started rotating in the opposite direction of treatment and thereby returning blood from the arterial segment / blood tubing system to the patient. In this case, the delivery rate of the arterial blood pump can be adjusted to the flow rate / volume of the dialysate transferred through the membrane. By interrupting arterial reinfusion, the serial reinfusion process is generally terminated.

[0021] Alternatively, serial blood return or reinfusion can be implemented such that blood is first returned to the patient from the arterial blood tubing side / arterial segment, and then only blood from the venous blood tubing side / venous segment is reinfused. Here, reinfusion is preferably initiated by overpressure on the dialysate side of the dialyzer after the blood treatment is completed. This overpressure forces the dialysate through the dialyzer membrane and serves as the reinfusion fluid. If the venous tubing clamp is now closed or remains closed, the arterial tubing clamp is open or remains open, and the arterial blood pump begins to rotate in the opposite direction of treatment, then blood is returned to the patient from the arterial segment / blood tubing system. Here, the delivery rate of the arterial blood pump can be adjusted to the flow rate / volume of the dialysate transferred through the membrane. After interruption of arterial reinfusion (e.g., by stopping the arterial blood pump / closing the arterial tubing clamp), the reinfusion direction is advantageously reversed. In particular, the venous tubing clamp is then opened, and blood in the venous tubing segment / segment is expelled towards the patient by the transferred dialysate. By interrupting intravenous reinfusion, the serial reinfusion process is generally terminated.

[0022] In other words, the serial blood return of the "arterial vein" is performed in a similar manner to the serial blood return of the "venous artery". Only by controlling the machine components in this way can the arterial segment be emptied first and then the venous segment.

[0023] Advantageously, the control unit is designed to control reinfusion based on the dialyzer used.

[0024] In particular, the control unit can be designed to classify the dialyzers used as high-flux dialyzers or low-flux dialyzers according to their ultrafiltration coefficient (KUF), and to implement appropriate control (flow pump inlet) based on the classification, particularly high-flux control or low-flux control.

[0025] In principle, low-flux dialyzer membranes have small pores, while high-flux dialyzer membranes have large pores. Therefore, it is obvious that liquid can pass through a high-flux dialyzer membrane more easily / better than a low-flux dialyzer membrane. To achieve the desired flow rate (flow rate / volume flow rate), the pressure in the low-flux dialyzer must be forcibly regulated to be greater than the pressure in the high-flux dialyzer.

[0026] Therefore, in accordance with this disclosure, the control of reinfusion is advantageously matched to the dialyzer used.

[0027] Here, the ultrafiltration coefficient of the control unit can be known, for example, if information about the dialyzer used (including the ultrafiltration coefficient) is read by a reading device and transmitted to the control unit before the blood treatment, or if the information is manually entered by the user before the blood treatment, or if the control unit can determine the ultrafiltration coefficient during the blood treatment. For example, a constant ultrafiltration flow rate (QUF) (e.g., 70 ml / min) can be adjusted during the blood treatment, and the transmembrane pressure can be determined after a short adjustment time (e.g., 40 seconds). The ultrafiltration coefficient (KUF) can be calculated in a known manner from this information.

[0028] Preferably, high-flux control is implemented when the ultrafiltration coefficient is greater than a predetermined value, for example, 20 ml / (min*mmHg), and low-flux control is implemented when the ultrafiltration coefficient is less than the predetermined value. Advantageously, in dialyzers from foreign manufacturers, the ultrafiltration coefficient of the corresponding dialyzer can also be determined according to this disclosure, and it can be classified as a high-flux dialyzer or a low-flux dialyzer so that reinfusion can be controlled accordingly.

[0029] Preferably, the control unit is designed to perform a (safe) air removal step after blood treatment and before re-infusion, by means of which air or bubbles are removed from the arterial segment.

[0030] Advantageously, an arterial hose clamp and an arterial blood pump are provided in the arterial segment, and a venous expansion chamber / air trap is provided in the venous segment. The control unit performs the (safe) air removal step such that the arterial segment is first clamped by the arterial hose clamp for a predetermined duration (e.g., two seconds), while the arterial blood pump continues to operate in the treatment direction. The resulting negative pressure draws air or air bubbles present in the arterial segment and transports them to the venous segment where they are eliminated in the venous expansion chamber.

[0031] As demonstrated by this disclosure, during blood treatment / dialysis, particularly when the extracorporeal blood circuit and dialyzer are filled with blood, air bubbles are located at the inlet of the arterial blood pump. However, in principle, air or air bubbles can also be located in other segments / locations within the arterial section of the extracorporeal circuit. During arterial reinfusion, particularly when the arterial blood pump is operated in the opposite direction of treatment, there is a risk that air bubbles located in the arterial segment may no longer be removed from the extracorporeal circuit (e.g., because there is no arterial expansion chamber / air trap for air bubble removal) and thus reach the patient. This must be absolutely avoided, as air bubbles are harmful to the patient.

[0032] If the safety procedure step (safety air removal step) is performed by the control unit before re-infusion, intact arterial blood return can be ensured.

[0033] Advantageously, the predetermined limit value of the hematocrit fraction is less than or equal to 10%, preferably between 2% and 5%, and particularly preferably 3%. For example, according to this disclosure, the predetermined limit value is determined to be a hematocrit fraction of 5% or 3%, such that when the hematocrit fraction is less than or equal to 5% or less than or equal to 3%, it is below the predetermined limit value.

[0034] In particular, as demonstrated by this disclosure, when a predetermined limit value for the hematocrit fraction is set as a percentage within the range, reinfusion will not be interrupted prematurely, i.e., reinfusion will not be performed while there is still an excessive amount of the patient's blood in the extracorporeal circuit. Preferably, the predetermined limit value should not be set too low, for example, less than 2%, as this would result in excessive delivery of dialysate / reinfusion fluid to the patient. Particularly preferably, according to this disclosure, the predetermined limit value is set at 3%. When the 3% limit value is mentioned according to this disclosure, it is not understood as "exactly 3%" but rather "approximately / about 3%".

[0035] According to a preferred embodiment, the first sensor is a venous safety air detector with an integrated red detector designed to identify air or bubbles in the fluid flowing through the venous segment and to detect the hematocrit fraction of the fluid as a criterion for interruption of reinfusion via the venous segment; and the second sensor is an arterial safety air detector with an integrated red detector designed to identify air or bubbles in the fluid flowing through the arterial segment and to detect the hematocrit fraction of the fluid as a criterion for interruption of reinfusion via the arterial segment.

[0036] In other words, a preferred embodiment is characterized by having or providing safety air detectors with integrated red detectors not only on the arterial side / in the arterial segment but also on the venous side / in the venous segment. Therefore, it is preferable to provide two safety air detectors with integrated red detectors in the extracorporeal blood processing device, which are capable of reliably identifying air or air bubbles and also detecting hematocrit limits as a criterion for interrupting re-infusion.

[0037] Because this embodiment can reliably detect air or air bubbles in both the arterial and venous segments (by providing two safety air detectors), it is not necessary to forcibly implement the aforementioned (safe) air removal steps. Since if air or air bubbles are located in the arterial segment, they will also be detected by the provided safety air detectors as soon as they become loose and are directed towards the patient, and the control unit can, in principle, interrupt re-infusion by stopping the arterial blood pump or by closing the arterial or venous tubing clamp.

[0038] Because this embodiment includes a safety air detector (so-called SADRDV sensor) with an integrated red detector in both the arterial and venous segments, the red value / chromaticity of the hemodialysis fluid mixture in the corresponding tubing segment can be determined, particularly when the blood-dialysis fluid mixture flows through the arterial / venous / corresponding tubing segment. Using the safety air detector with the integrated red detector, the hematocrit fraction of the hemodialysis fluid mixture can be determined fairly accurately from the detected red value. This also applies when the hematocrit fraction is already very low. Once the red detector of the SADRDV sensor detects a hematocrit fraction below the aforementioned predetermined limit (e.g., less than 3%), re-infusion in the corresponding tubing system is terminated, where the value below the predetermined limit is detected.

[0039] In principle, it may occur that blood in one segment of the extracorporeal circuit / in one section of the blood tubing system (e.g., in the arterial segment) is drawn back faster than blood in another segment of the extracorporeal circuit / in another section of the blood tubing system (e.g., in the venous segment). In this case, the control unit is designed to maintain or reduce the delivery / flow rate of dialysate through the dialyzer membrane and is now guided entirely through the segment of the extracorporeal circuit where reinfusion has not been interrupted.

[0040] If blood re-infusion via the venous segment of the extracorporeal circuit is interrupted prematurely, the control unit, for example, closes the venous tubing clamp and operates the arterial blood pump to run it at a rate that delivers the transferred dialysate in the opposite direction of treatment. This transferred dialysate / reinfusion fluid then drains the remaining blood into the arterial portion of the blood tubing system until the SADRDV sensor located there detects the determined hematocrit limit.

[0041] When blood reinfusion is interrupted earlier in the arterial segment of the extracorporeal circuit, the arterial blood pump is stopped and the arterial tubing clamp is closed. The transferred reinfusion fluid / dialysis fluid then drains the remaining blood into the venous segment of the extracorporeal circuit until the SADRDV sensor located there detects the determined hematocrit limit.

[0042] Here, the air detector of the SADRDV sensor continuously monitors to ensure no air enters the patient. If an air bubble is detected, the control unit stops the re-infusion process. Specifically, the control unit then closes the arterial and venous tubing clamps, maintains the blood pump, and increases the overpressure on the dialysate side of the dialyzer (e.g., by stopping the flow pump inlet and opening the dialyzer outlet valve).

[0043] If reinfusion is performed serially instead of in parallel, the reinfusion method described above can be used similarly. During serial reinfusion, for example, when blood is first reinfused to the patient via a venous segment of the extracorporeal circuit, the red detector of the SADRDV sensor detects / monitors the hematocrit fraction of the blood or hemodialysis fluid mixture. Here, if the red detector detects a hematocrit fraction below a predetermined limit (e.g., less than 3%), the reinfusion via the venous segment is interrupted or terminated. In the exemplary case described, reinfusion is performed via an arterial segment. The red detector of the SADRDV sensor, located in the arterial segment, detects / monitors the hematocrit fraction of the blood or hemodialysis fluid mixture in the arterial segment. Here, if the red detector detects a hematocrit fraction below a predetermined limit (e.g., less than 3%), the reinfusion via the arterial segment is also interrupted or terminated.

[0044] According to another or alternative preferred embodiment, the first sensor is a venous safety air detector with an integrated red detector designed to identify air or bubbles in the fluid flowing through the venous segment and to detect the hematocrit fraction of the fluid as a criterion for interruption of reinfusion via the venous segment, and the second sensor is a hematocrit sensor (HTC sensor) designed to detect information about the hematocrit fraction in the fluid during reinfusion and to forward the information to the control unit.

[0045] In other words, in principle, instead of a safety air detector (SADRDV sensor) with an integrated red detector, a hematocrit sensor or HTC sensor for detecting hematocrit fraction can be used in the arterial segment of the extracorporeal blood circuit. In particular, many extracorporeal blood processing devices / dialysis machines already have hematocrit sensors (HTC sensors) compliantly installed in the arterial segment of the extracorporeal circuit. Therefore, the described embodiment has the advantage that an additional safety air detector (hardware change) does not need to be integrated on the arterial side / arterial segment; rather, only a software change is required in many machines.

[0046] Because the HTC sensor does not include an air detector, in this embodiment, it is essential to ensure that air does not enter the patient in a suitable manner. To avoid the need to integrate an additional air detector into the arterial segment of the extracorporeal circuit, the aforementioned (safe) air removal step is absolutely necessary or mandatory in this embodiment.

[0047] In particular, it has been demonstrated according to this disclosure that the above-described safe air removal step enables the omission of air detectors in the arterial segment of the extracorporeal circuit, and thus advantageously allows the use of only cost-effective hematocrit sensors already present in many dialysis machines in the arterial segment.

[0048] However, a problem exists in this regard: only a single air detector with an integrated red detector (SADRDV sensor) can reliably measure hematocrit fraction at small percentage values. Hematocrit sensors (HTC sensors) can only reliably measure hematocrit values / fractions within a range of 20% to 55%, with a sacrifice in the range of 10% to 55%. However, since the predetermined limit value according to this disclosure is less than 10%, the hematocrit sensor cannot reliably detect when the predetermined limit value of this disclosure is exceeded. In this context, particularly when using a hematocrit sensor, there is a need for the control unit to calculate or predict when the hematocrit fraction will fall below the predetermined limit value based on the information detected by the hematocrit sensor.

[0049] Preferably, the control unit is therefore designed to calculate or predict, based on information about the hematocrit fraction in the fluid, when the hematocrit fraction of the fluid will fall below a predetermined limit. In other words, the control unit preferably uses information transmitted to it by the hematocrit sensor, particularly information about the hematocrit fraction within a percentage range reliably measured by the control unit, to calculate or predict when it is expected to fall below the predetermined limit, and to interrupt the re-infusion process based on this calculation / prediction.

[0050] More preferably, the control unit is designed to perform the calculation or prediction using a linear function when the control unit serially / continuously / sequentially performs reinfusion via the venous segment and reinfusion via the arterial segment, or when the reinfusion flow rate in the arterial segment or the venous segment is large or greater than a predetermined threshold (e.g., 75 ml / min).

[0051] More preferably, the control unit is designed to perform the calculation or prediction using a Gaussian function (first order) when the control unit performs reinfusion via the venous segment and reinfusion via the arterial segment in parallel / simultaneously / at the same time, or when the reinfusion flow rate in the arterial segment or the venous segment is small or less than a predetermined threshold (e.g., 75 ml / min).

[0052] In other words, the control unit is preferably designed to calculate or predict using a linear function when the reinfusion flow rate is above a predetermined limit / threshold, and to calculate or predict using a Gaussian function when the reinfusion flow rate is below the predetermined limit / threshold. Therefore, if the reinfusion flow rate is high and there is less mixing between the blood and dialysate during reinfusion, a linear function is used for prediction; conversely, if the reinfusion flow rate is low and there is therefore more mixing between the blood and dialysate during reinfusion, a Gaussian function is used for prediction.

[0053] Therefore, the control unit is designed to intelligently evaluate the measurement results of the hematocrit sensor when the hematocrit sensor (HTC sensor) is used to measure hematocrit fraction.

[0054] In summary, this disclosure therefore relates to an extracorporeal blood processing device comprising: an extracorporeal circuit, a dialyzer, a dialysate circuit, and a control unit. Sensors are provided not only in the venous section of the extracorporeal circuit but also in the arterial section, and these sensors are designed to detect the hematocrit fraction in the fluid flowing through the respective sections. The control unit is designed to control the reinfusion of blood such that dialysate is supplied from the dialysate circuit through the dialyzer membrane to the extracorporeal circuit, and the dialysate, upon reinfusion, displaces blood present in the extracorporeal circuit toward the patient so as to return blood to the patient via the venous and arterial sections. Here, when the hematocrit fraction is detected by the corresponding sensor or calculated or predicted by the control unit based on information detected by the corresponding sensor, the reinfusion in the corresponding section of the extracorporeal circuit is interrupted under sensor control.

[0055] This disclosure generally provides an automated and direct initiation of reinfusion after dialysis treatment. Reinfusion according to this disclosure saves on material costs because a saline bag is not used for reinfusion. Furthermore, reinfusion can also be used in machines without a replacement fluid port. This disclosure allows caregivers to avoid active intervention between the end of dialysis treatment and the start of reinfusion. In particular, there is no need for interaction with caregivers to decouple the patient connector. Furthermore, this disclosure provides an improved reinfusion interruption when reinfusion is performed not only via the arterial segment of the extracorporeal circuit but also via the venous segment. Additionally, it ensures that air does not enter the patient.

[0056] Furthermore, this disclosure relates to a method for automatically re-infusing blood after blood treatment, the method comprising the steps of: providing dialysate from a dialysate circuit via a dialyzer membrane to an extracorporeal circuit; draining blood present in the extracorporeal circuit to a patient; reinfusing blood to the patient not only via a venous segment of the extracorporeal circuit but also via an arterial segment of the extracorporeal circuit; interrupting re-infusion via the venous segment when a first sensor located in the venous segment detects, or when information detected by the first sensor predicts or calculates, that the fluid containing blood flowing through the venous segment is below a predetermined limit; and interrupting re-infusion via the arterial segment when a second sensor located in the arterial segment detects, or when information detected by the second sensor predicts or calculates, that the fluid containing blood flowing through the arterial segment is below a predetermined limit.

[0057] In order to implement the method according to the invention, it is preferable to perform antegrade puncture (along the flow direction) of the arterial needle in the patient, because turbulence may be generated in the blood vessel when the arterial needle is punctured retrogradely (relative to the flow direction).

[0058] After implementing the method according to this disclosure, or after interrupting reinfusion via the arterial and venous segments and closing the actual arterial and venous hose clamps, the patient can be decoupled from the caregiver's artery and vein. Advantageously, the patient-side connectors are then interconnected or short-circuited. In other words, preferably, the end of the arterial segment is connected to the end of the venous segment. Advantageously, the method described in EP3231466B1 is then implemented. In particular, EP3231466B1 provides a suitable method for emptying the blood tubing system and the dialyzer on the vascular side after patient decoupling. Attached Figure Description

[0059] The present disclosure will now be further illustrated with reference to the accompanying drawings. The drawings show:

[0060] Figure 1An extracorporeal blood processing device according to a first preferred embodiment of the present disclosure is shown, by means of which automatic re-infusion according to the present disclosure is explained;

[0061] Figure 2 An extracorporeal blood processing device according to a second preferred embodiment of the present disclosure is shown, by means of which the automatic re-infusion according to the present disclosure is explained;

[0062] Figure 3 A view of an arterial blood pump prior to the implementation of the safety air removal step according to this disclosure;

[0063] Figure 4 A view of an arterial blood pump after the implementation of the safety air removal step according to this disclosure;

[0064] Figure 5 The graph illustrates the change in air volume flow rate delivered to the patient over time during reinfusion via an extracorporeal circuit to the arterial segment after implementing the safe air removal step according to this disclosure.

[0065] Figure 6 The diagram should illustrate the prediction of hematocrit fraction using a linear function when reinfusion is performed sequentially via arterial and venous segments.

[0066] Figure 7 The diagram should illustrate the prediction of hematocrit fraction using a linear function when reinfusion is performed in parallel via arterial and venous segments; and

[0067] Figure 8 The diagram should illustrate the prediction of hematocrit fraction using a Gaussian function when reinfusion is performed in parallel via arterial and venous segments.

[0068] Wherein: 2-Extracorporeal blood processing equipment; 4-Extracorporeal circuit; 6-Dialyzer; 8-Dialysate circuit; 10-Membrane; 12-Arterial segment; 14-Venous segment; 15-Patient; 16-Venous expansion chamber / air trap; 18-Venous safety air detector (SADRDV sensor) with integrated red detector; 20-Venous hose clamp; 22-Arterial hose clamp; 24-Arterial safety air detector (SADRDV sensor) with integrated red detector; 26-(Arterial) blood pump; 28-Arterial pressure sensor; 30-Dialyzer inlet pressure sensor; 32-Venous pressure sensor; 34-Dialyzer inlet valve; 36-Dialyzer outlet valve; 38-Flow pump inlet; 40-Flow pump outlet; 42-Dialysate inlet; 44-Dialysate outlet; 46-Control unit; 48-Hematocrit sensor (HTC sensor); 50-Bubbles. Detailed Implementation

[0069] The accompanying drawings are illustrative in nature and are intended only for understanding the invention. The same elements are referred to by the same reference numerals. Features of the various embodiments may be interchanged unless otherwise expressly stated.

[0070] Figure 1 An extracorporeal blood processing device (dialysis machine) 2 according to a first preferred embodiment of the present disclosure is shown, by means of which automatic re-infusion according to the present disclosure is explained.

[0071] The extracorporeal blood processing device 2 basically includes an extracorporeal circuit (A / V tubing system) 4, a dialyzer 6, and a dialysate circuit 8. Here, the extracorporeal circuit 4 and the dialysate circuit 8 are separated from each other via a membrane 10 disposed in the dialyzer 6.

[0072] The extracorporeal circuit 4 includes an arterial segment 12 located upstream of the dialyzer 6 and a venous segment 14 located downstream of the dialyzer 6.

[0073] Depend on Figure 1 It can be seen that arterial segment 12 and venous segment 14 are coupled to patient 15. In other words, the end of arterial segment 12 is coupled to the artery of patient 15, and the end of venous segment 14 is coupled to the vein of patient 15.

[0074] In the venous section 14 of the extracorporeal circuit 4, a venous expansion chamber or air trap 16, a venous safety air detector with an integrated red detector 18, and a venous tubing clamp 20 are located downstream of the dialyzer 6 (i.e., in the direction from the dialyzer 6 toward the end of the venous section 14).

[0075] In arterial segment 12, starting from the patient-side end of arterial segment 12 and moving towards dialyzer 6, are provided an arterial hose clamp 22, an arterial safety air detector with an integrated red detector 24, and an (arterial) blood pump 26. (As in...) Figure 1 As can be seen, the external circuit 4 (in particular its blood pump adapter) has been inserted into the blood pump 26, which is preferably configured as a roller pump or peristaltic pump and is set up to deliver fluid / liquid by squeezing the tubing.

[0076] In the arterial segment 12, the arterial pressure upstream of or in front of the blood pump 26 can be measured using arterial pressure sensor 28. Furthermore, the dialyzer inlet pressure can be measured downstream of or after the blood pump 26 and upstream of or in front of the dialyzer 6 (between the dialyzer 6 and the blood pump 26) using dialyzer inlet pressure sensor 30. In the venous segment 14, the venous pressure at / after the venous expansion chamber or air trap 16 can be measured using venous pressure sensor 32. Pressure sensors 28, 30, and 32, located in the extracorporeal circuit 4, can measure / retrieve / monitor pressure at corresponding locations within the extracorporeal circuit 4, where the pressure sensors are located / set.

[0077] The dialysate circuit 8 includes a dialyzer inlet valve 34, a dialyzer outlet valve 36, a flow pump inlet 38, and a flow pump outlet 40. However, in principle, it is sufficient to provide only one flow pump, such as the flow pump inlet 38, in the dialysate circuit 8. The dialyzer inlet valve 34 and the flow pump inlet 38 are located upstream of the dialyzer 6 at the dialysate inlet 42. The dialyzer outlet valve 36 and the flow pump outlet 40 are located downstream of the dialyzer 6 at the dialysate outlet 44. Preferably, the flow pump inlet 38 and the flow pump outlet 40 are gear pumps.

[0078] Furthermore, the extracorporeal blood processing device 2 has a control unit 46, which is preferably configured as a processor, particularly as a central computing / processing unit (CPU). The control unit 46 obtains information from sensors disposed within the extracorporeal blood processing device 2. Here, only exemplary examples are provided. Figure 1 The sensors shown include the arterial pressure sensor 28, the dialyzer inlet pressure sensor 30, the venous pressure sensor 32, the arterial safety air detector with an integrated red detector 24, and the venous safety air detector with an integrated red detector 18. On the other side, the control unit 46 controls or manipulates the actuators disposed in the extracorporeal blood processing device 2. Here, only exemplary examples are listed. Figure 1 The valves, pumps, hose clamps, etc. shown, especially dialyzer inlet valve 34, dialyzer outlet valve 36, flow pump inlet 38, flow pump outlet 40, (arterial) blood pump 26, arterial hose clamp 22, venous hose clamp 20, etc.

[0079] exist Figure 2 The structure of the extracorporeal blood processing device (dialysis machine) 2 shown (the second preferred embodiment of this disclosure) is similar to that in... Figure 1 The only hardware difference in the structure shown is that instead of an arterial safety air detector with an integrated red detector 24, a hematocrit sensor (HTC sensor) 48 is arranged in the arterial segment 12 of the external circuit 4. Furthermore, in Figure 2 The structure shown is similar to that in Figure 1 The structures shown are the same, therefore the foregoing embodiments and descriptions are applicable in accordance with the present invention. Figure 2 The structure shown is identical, and therefore not repeated.

[0080] Figure 1 and Figure 2 The images show the patient's condition immediately after the completion of blood processing therapy. In this condition, it is desirable to return / reinfuse the blood still present in extracorporeal circuit 4 to the patient.

[0081] exist Figure 1 In the illustrated embodiment, a safety air removal step can be selectively performed after blood treatment has ended and before re-infusion begins. Figure 2 In the embodiment shown, the safety air removal step is mandatory. This is because in Figure 2 In the embodiment shown, there is no safety air detector in arterial segment 12.

[0082] The control unit 46 performs the safe air removal step such that, while the arterial blood pump 26 continues to operate in the treatment direction, the control unit first clamps the arterial segment 12 with the arterial hose clamp 22 for approximately two seconds. Here, a negative pressure is generated in the arterial segment 12, which carries any air or air bubbles 50 that may be present and transports them to the venous segment 14, where the air or air bubbles 50 in the venous expansion chamber 16 are eliminated.

[0083] As by Figure 3 It has been found that air bubbles 50 are often located at the inlet of the arterial blood pump 26 after the blood treatment is completed. Such air bubbles 50 can be removed in a suitable manner by the safe air removal procedure according to this disclosure. In particular, Figure 4 The arterial blood pump 26 is shown after the described safety air removal step has been performed. Figure 4 In this process, bubble 50 is no longer present and has been appropriately eliminated through a safe air removal step. This is also achieved through... Figure 5 The diagram shown illustrates this. Figure 5 The diagram shows the volume / volume flow rate / flow rate of bubbles / microbubbles over time during arterial re-infusion after the implementation of the safety air removal step. The maximum bubble volume / flow rate is shown to be 19 nl / s. The bubble flow rate is significantly lower than the specified maximum flow rate (500 nl / (s*kg)), therefore, the safety air removal step according to this disclosure enables reliable air removal.

[0084] In the present case, the control unit 46 is essentially designed to automatically control the re-infusion of blood after blood treatment or, if necessary, after a safety air removal step, such that dialysate is supplied from dialysate circuit 8 via membrane 10 of dialyzer 6 to extracorporeal circuit 4, which, upon re-infusion, displaces blood present in extracorporeal circuit 4 toward patient 15 so that blood is returned to patient 15 not only via venous segment 14 but also via arterial segment 12.

[0085] According to this disclosure, the control unit 46 manipulates components present in the dialysate circuit 8 to generate overpressure in the dialysate circuit 8, which causes dialysate / reinfusion fluid to appear via the membrane 10 of the dialyzer 6. Preferably, the overpressure is generated by the control unit 46 manipulating the flow pump inlet 38, thus pumping the dialysate into the dialyzer 6, opening the dialyzer inlet valve 34, closing the dialyzer outlet valve 36, and stopping the flow pump outlet 40. Thus, a suitable pressure (transmembrane pressure) is applied to the membrane 10 of the dialyzer 6 through the dialysate. This pressure causes dialysate with a defined flow rate (flow rate / volume flow rate) for example, 100 ml / min (depending on the dialyzer used) to be transferred from the dialysate circuit 8 to the extracorporeal circuit 4 via the membrane 10 of the dialyzer 6.

[0086] Basically, the control unit 46 can implement control based on the dialyzer 6 used. To this end, the control unit 46 classifies the dialyzer 6 used, for example, as a high-flux dialyzer or a low-flux dialyzer, and implements high-flux control or low-flux control based on this classification, in particular by correspondingly controlling the flow pump inlet 38.

[0087] According to this disclosure, the control unit 46 can perform reinfusion via arterial segment 12 and via venous segment 14 in parallel or serially.

[0088] During parallel reinfusion, the arterial blood pump 26 is driven by the control unit 46 in the opposite direction of treatment to deliver blood / fluid from the dialyzer 6 to the end of the arterial segment 12. For this purpose, the blood pump 26 can be regulated by the control unit 46 to a constant delivery rate less than the flow rate through the membrane 10 of the dialyzer 6. For example, the delivery rate of the blood pump 26 can be adjusted to 50 ml / min. When the defined flow rate through the membrane 10 of the dialyzer 6 is 100 ml / min, the flow rate in the venous segment 14 in the treatment direction towards the end of the venous segment 14 corresponds to the arterial flow rate. If the arterial hose clamp 22 and the venous hose clamp 20 are now opened, blood in the arterial segment 12 and the venous segment 14 in the extracorporeal circuit 4 can be expelled towards the patient 15 through the overflowing dialysate. Parallel reinfusion ends when both arterial and venous reinfusions have been interrupted by the control unit 46 (by closing the arterial hose clamp 22 and the venous hose clamp 20).

[0089] If re-infusion of blood via venous segment 14 is interrupted earlier than re-infusion of blood via arterial segment 12 during parallel re-infusion, control unit 46 closes venous tubing clamp 20 and increases the delivery rate of arterial blood pump 26. If re-infusion via arterial segment 12 is interrupted earlier, control unit 46 stops arterial blood pump 26 and closes arterial tubing clamp 22, so that overflowing dialysate now only drains the remaining blood in venous segment 14.

[0090] In a serial reinfusion, for example, blood from venous segment 14 can be infused back to patient 15 first, followed by reinfusion of blood from arterial segment 12. In this case, arterial blood pump 26 stops, venous hose clamp 20 is opened, and blood in venous segment 14 is drained towards patient 15 through overflowing dialysate. After the venous reinfusion is interrupted (by closing venous hose clamp 20), arterial hose clamp 22 is opened (or kept open), and arterial blood pump 26 begins to rotate in the opposite direction of treatment, so that blood is now also infused back to patient 15 from arterial segment 12. The delivery rate of arterial blood pump 26 can here be adjusted to the flow rate of dialysate overflowing through membrane 10. The serial reinfusion process ends by interrupting arterial reinfusion.

[0091] Alternatively, in serial reinfusion, blood can first be returned from arterial segment 12 to patient 15, followed by reinfusion of blood from venous segment 14. In this case, venous hose clamp 20 is first closed or kept closed, arterial hose clamp 22 is opened or kept open, and arterial blood pump 26 begins to rotate in the opposite direction of treatment, causing blood from arterial segment 12 to be returned to patient 15. The delivery rate of arterial blood pump 26 is here adjusted to the flow rate of dialysate overflowing through membrane 10. After arterial reinfusion is interrupted (e.g., by stopping arterial blood pump 26 / closing arterial hose clamp 22), venous hose clamp 20 is opened, and blood in venous segment 14 is drained toward patient 15 by overflowing dialysate. By interrupting venous reinfusion, the serial reinfusion process is generally terminated.

[0092] The following will discuss in more detail the basis Figure 1This is a first preferred embodiment of the present disclosure. According to this embodiment, safety air detectors with integrated red detectors are provided not only in the arterial segment 12 but also in the venous segment 14; specifically, an arterial safety air detector with integrated red detector 24 and a venous safety air detector with integrated red detector 18. The two safety air detectors with integrated red detectors 18 and 24 reliably detect air or air bubbles. If air or air bubbles are detected, the control unit, according to this embodiment, interrupts re-infusion by stopping the arterial blood pump 26 or by closing the arterial hose clamp 22 or the venous hose clamp 20.

[0093] The safety air detectors with integrated red detectors 18 and 24 are designed to determine hematocrit fraction fairly accurately, even when the percentage value is relatively small. According to a first preferred embodiment, arterial re-infusion is interrupted when the arterial safety air detector, by means of the integrated red detector 24, detects that the hematocrit fraction in the distal region of arterial segment 12 is below a predetermined limit (preferably 3%). Similarly, venous re-infusion is interrupted if the venous safety air detector with integrated red detector 18 detects that the hematocrit fraction in the distal region of venous segment 12 is below a predetermined limit.

[0094] The following will discuss in more detail the basis Figure 2 This is a second preferred embodiment of the present disclosure. According to this embodiment, a venous safety air detector with an integrated red detector 18 is provided in the venous segment 14, and a hematocrit sensor / HTC sensor 48 is provided in the arterial segment 12.

[0095] Since the hematocrit sensor 48 is capable of reliably measuring hematocrit values / fractions within a range of only 20% to 55%, and the predetermined limit value is less than 10%, particularly less than 3%, according to this disclosure, the measurement results of the hematocrit sensor 48 are intelligently evaluated by the control unit 46 according to this disclosure in order to predict / calculate when the value falls below the predetermined limit value.

[0096] For serial reinfusion (blood return via arterial segment 12 and venous segment 14 at a flow rate of 100 ml / min), refer to... Figure 6 The diagram shown illustrates this intelligent assessment. For parallel reinfusion (blood return via arterial segment 12 and venous segment 14 at a flow rate of 50 ml / min), refer to... Figure 7 and Figure 8 The charts in the document illustrate this intelligent assessment.

[0097] In order to intelligently evaluate the hematocrit sensor 48, the measured change curve of the hematocrit sensor 48 must be compared with the actual change curve of the hematocrit fraction. For experimental purposes, the SADRDV sensor is integrated into the arterial segment 12 as a reference sensor. The high-flux dialyzer "XevtHi23" is used in the experiment described below.

[0098] exist Figure 6 The diagram for serial reinfusion only shows the change in hematocrit fraction for arterial blood reinfusion, measured by hematocrit sensor 48. In the experiment, the blood tubing system between hematocrit sensor 48 and dialyzer 6 contained approximately 40 ml. At a flow rate of 100 ml / min, it was found that relatively undiluted blood passed through hematocrit sensor 48 for approximately 24 seconds (at...). Figure 6 The hematocrit fraction decreases only slightly. After 24 seconds, the hematocrit fraction decreases significantly until it reaches 0% within 17 seconds (according to hematocrit sensor 48). When hematocrit sensor 48 detects a sharp decrease in hematocrit, point P1 can be defined. When the hematocrit fraction measured by hematocrit sensor 48 is at a percentage value that hematocrit sensor 48 also precisely measures, i.e., 20%, a second point P2 can be defined. Figure 6 In this context, P2 is defined when the hematocrit fraction is 10%. A linear function f(t) = 1.8 * t + 72.6 (for t > 24 s) is defined through points P1 and P2. Therefore, for f(t) = 0, a time of 40 seconds is obtained. However, based on reference measurements using the SADRDV sensor, it is known that the hematocrit fraction first falls below a predetermined limit of 3% after 55 seconds, resulting in a 15-second offset (for the dialyzer used, the set flow rate, and the tubing system used). In this context, to intelligently evaluate the hematocrit sensor measurements, the control unit 46 can define points P1 and P2, define a linear function f(t) extending through points P1 and P2, and, if necessary, calculate the offset relative to the linear function f(t) = 0 to determine when it falls below the predetermined limit. However, this approximation only works when the offset is small (especially less than 20 seconds).

[0099] according to Figure 7 An attempt has been made to determine when the hematocrit level falls below a predetermined limit during parallel reinfusion by applying a linear function to the measurement curve of the hematocrit sensor 48. Figure 7 It was found that the change curve of hematocrit fraction measured by hematocrit sensor 48 during parallel reinfusion differed from that during serial reinfusion. Specifically, in... Figure 7The hematocrit fraction did not decrease significantly during the first 63 seconds because the blood in the arterial segment 12 of the extracorporeal circuit 4 passed through the hematocrit sensor 48 relatively undiluted. Due to the flow rate of only 50 ml / min, this process lasted approximately twice as long as during serial reinfusion. Then, the hematocrit fraction decreased to 20% at a constant gradient within 34 seconds. It then rapidly decreased to 0% hematocrit fraction within 18 seconds. Therefore, a distinct decrease in hematocrit fraction was observed overall within the numerical range of 33% to 17% and within the numerical range of 17% to 0%. In this context, it can be assumed that the reliable measurement range of the hematocrit sensor 48 is only approximately 20%. Within this range, Figure 7 The diagram shows a linear function with the following equation: f(t) = 0.36*t + 54.23 [t > 48 seconds]. For this function to be applicable, f(t) = 0 exists at 156 seconds. However, in the current case, the actual time measured by the reference sensor is 221 seconds, down to below a predetermined limit of 3%. In this context, the offset during parallel re-infusion is too large for the linear function to predict values ​​below the predetermined limit.

[0100] As by Figure 8 It has been demonstrated, according to this disclosure, that a first-order Gaussian function can be used to predict / calculate when the hematocrit fraction falls below a predetermined limit for use in parallel retransfusion. Specifically, the Gaussian function can be derived when the hematocrit fraction is recorded from a hematocrit sensor at 48% to 20%. In particular, three points P0, P1, and P2 on the hematocrit change curve are used to derive the Gaussian function, where P0 is the starting point, P1 is the point from which the hematocrit fraction decreases with a constant gradient, and P2 is the point from which the hematocrit sensor reliably measures (approximately 20%) the hematocrit fraction up to that point. If the maximum value Pmax of the Gaussian function is now positioned such that it lies exactly midway between P0 and P1 on the time axis, and the inflection point Pinflection of the Gaussian function is defined such that it lies exactly midway between the distances between P1 and P2, then the Gaussian function can be derived as follows: Figure 8 The following definitions are shown:

[0101]

[0102] As by Figure 8 It is found that f(t) = 0 exists for this function at approximately 216 seconds. Therefore, this function can be used to predict, in a suitable manner, when the value falls below a predetermined limit of 3%, especially when small offsets are added.

Claims

1. An extracorporeal blood processing device (2), comprising: The extracorporeal circuit (4) includes an arterial segment (12) and a venous segment (14), a dialyzer (6), and a dialysate circuit (8), wherein, The extracorporeal circuit (4) and the dialysate circuit (8) are separated from each other via a membrane (10) disposed in the dialyzer (6); A first sensor (18) is provided in the vein segment (14), the first sensor being designed to detect the hematocrit fraction of the fluid flowing through the vein segment (14); A second sensor (24, 48) is provided in the arterial segment (12), the second sensor being designed to detect the hematocrit fraction of the fluid flowing through the arterial segment (12); and The extracorporeal blood treatment device (2) further includes a control unit (46) designed to control the re-infusion of blood such that dialysate is supplied from the dialysate circuit (8) via the membrane (10) of the dialyzer (6) to the extracorporeal circuit (4), the dialysate, during re-infusion, displaces blood present in the extracorporeal circuit (4) toward the patient (15) so as to return blood to the patient (15) via the venous segment (14) and the arterial segment (12). Its features are, The control unit (46) is designed to interrupt reinfusion via the venous segment (14) when the hematocrit fraction is detected by the first sensor (18) or calculated or predicted by the control unit (46) based on the information detected by the first sensor (18) and when the hematocrit fraction is detected by the second sensor (24, 48) or calculated or predicted by the control unit (46) based on the information detected by the second sensor (24, 48) and when the hematocrit fraction is detected by the second sensor (24, 48) and ... control unit (46) and predicted by the control unit (46) based on the information detected by the second sensor (24, 48) and when the reinfusion is interrupted via the arterial segment (12).

2. The extracorporeal blood processing device (2) according to claim 1, characterized in that, The predetermined limit value of the hematocrit fraction is less than or equal to 10%.

3. The extracorporeal blood processing device (2) according to claim 1 or 2, characterized in that, An arterial blood pump (26) is provided in the arterial segment (12), the arterial blood pump being designed to change the direction of rotation, and the control unit (46) operating the arterial blood pump (26) during re-infusion via the arterial segment (12) so that the arterial blood pump rotates in the opposite direction to the treatment direction.

4. The extracorporeal blood processing device (2) according to claim 1 or 2, characterized in that, The control unit (46) is designed to perform reinfusion via the venous segment (14) and reinfusion via the arterial segment (12) in parallel.

5. The extracorporeal blood processing device (2) according to claim 1 or 2, characterized in that, The control unit (46) is designed to perform reinfusion via the venous segment (14) and reinfusion via the arterial segment (12) in sequence.

6. The extracorporeal blood processing device (2) according to claim 1 or 2, characterized in that, The control unit (46) is designed to control the reinfusion according to the dialyzer (6) used.

7. The extracorporeal blood processing device (2) according to claim 1, characterized in that, The control unit (46) is designed to perform a safety air removal step after blood treatment and before re-infusion, by means of which air or bubbles are removed from the arterial segment (12).

8. The extracorporeal blood processing device (2) according to claim 7, characterized in that, An arterial hose clamp (22) and an arterial blood pump (26) are provided in the arterial segment (12), and a venous expansion chamber (16) is provided in the venous segment (14). The control unit (46) performs the safety air removal step such that the arterial segment (12) is clamped by the arterial hose clamp (22) for a predetermined duration, while the arterial blood pump (26) continues to operate in the treatment direction, wherein the resulting negative pressure drives the air or air bubbles (50) present in the arterial segment (12) and transports them to the venous segment (14) where they are eliminated in the venous expansion chamber (16).

9. The extracorporeal blood processing device (2) according to claim 1 or 2, characterized in that, The first sensor (18) is a venous safety air detector with an integrated red detector (18) designed to identify air or air bubbles in the fluid flowing through the venous segment (14) and detect the hematocrit of the fluid as a criterion for interruption of reinfusion via the venous segment (14), and the second sensor (24, 48) is an arterial safety air detector with an integrated red detector (24) designed to identify air or air bubbles in the fluid flowing through the arterial segment (12) and detect the hematocrit of the fluid as a criterion for interruption of reinfusion via the arterial segment (12).

10. The extracorporeal blood processing device (2) according to claim 7 or 8, characterized in that, The first sensor (18) is a venous safety air detector with an integrated red detector (18) designed to identify air or air bubbles in the fluid flowing through the venous segment (14) and detect the hematocrit fraction of the fluid as an interruption criterion for reinfusion via the venous segment (14), and the second sensor is a hematocrit sensor (48) designed to detect information about the hematocrit fraction in the fluid during reinfusion and forward the information to the control unit (46).

11. The extracorporeal blood processing device (2) according to claim 10, characterized in that, The control unit (46) is designed to calculate or predict, based on information about the hematocrit fraction of the liquid, when the hematocrit fraction of the liquid will fall below a predetermined limit.

12. The extracorporeal blood processing device (2) according to claim 11, characterized in that, The control unit (46) is designed to perform the calculation or prediction by means of a linear function when the control unit serially performs reinfusion via the venous segment (14) and reinfusion via the arterial segment (12), or when the reinfusion flow in the arterial segment (12) or the venous segment (14) is greater than or equal to a predetermined threshold.

13. The extracorporeal blood processing device (2) according to claim 11 or 12, characterized in that, The control unit (46) is designed to perform the calculation or prediction using a Gaussian function when the control unit performs reinfusion via the venous segment (14) and reinfusion via the arterial segment (12) in parallel, or when the reinfusion flow in the arterial segment (12) or the venous segment (14) is small or less than a predetermined threshold.

14. The extracorporeal blood processing device (2) according to claim 2, characterized in that, The predetermined limit for the hematocrit fraction is between 1% and 5%.

15. The extracorporeal blood processing device (2) according to claim 2, characterized in that, The predetermined limit value for the hematocrit fraction is 3%.

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