Air elimination device for extracorporeal blood treatment

Abstract

The present disclosure relates to a blood circulation system (6) for an extracorporeal blood treatment machine (1), comprising: an arterial circulation part (2); a venous circulation part (5); a dynamic bubble trap (7); and an air separator (10; 11), wherein the blood circulation system (6) is designed to guide blood from a patient to a dialysis unit (3) and from the dialysis unit (3) to the patient during operation of a blood pump (4) of the extracorporeal blood treatment machine (1); and comprises a recirculation or branch line (8) connected to the bubble trap (7) so as to return part of the blood flowing into the bubble trap (7) to the blood circulation system (6) upstream of the bubble trap (7). The present disclosure also relates to an extracorporeal blood treatment machine (1) comprising the blood circulation system (6) according to the present disclosure.

Description

Technical Field

[0001] The present disclosure relates to a blood circuit system for an extracorporeal blood treatment machine, comprising an arterial line portion, a venous line portion, a dynamic bubble trap, and an air separator, wherein the circuit system is designed to conduct blood from a patient to a dialysis unit and from the dialysis unit to the patient during operation of a blood pump of the extracorporeal blood treatment machine.

[0002] Public background

[0003] During blood processing using conventional blood processing machines, particularly hemodialysis, the blood flowing through the dialysis unit for purification becomes infused with microbubbles / microbubbles that can potentially flow back into the patient's body without causing alarm. These microbubbles can lodge in the patient's lungs, travel through the pulmonary capillaries, and potentially be distributed throughout the body via arteries, potentially causing organ failure. Because the formation of microbubbles in the blood flowing through the hemodialysis unit is a common side effect of hemodialysis, they must be separated from the blood before returning to the patient.

[0004] Dynamic bubble traps (DBTs) are well-known for their use in heart-lung machines. They are used to filter out microbubbles to achieve high blood flow / blood volume / blood mass flow. For example, US 6,478,962 B1 discloses a conventional dynamic bubble trap designed for use in heart-lung machines. The DBT accelerates blood radially as it flows through it, causing lighter microbubbles to migrate to the area around the central axis of the DBT, while heavier blood components are pushed radially outward under the action of centrifugal force. The blood containing microbubbles that accumulates in the area around the central axis is separated from the main blood flow and returned to the main blood flow.

[0005] This is not the case with conventional air separators / gas traps / blood traps used in dialysis devices. Depending on the installation direction / orientation of the air separator, the air bubbles migrate against the force of gravity to the center or upwards, where they can ultimately be extracted. This means that the air bubbles are essentially separated solely due to the density difference between the air bubbles and the blood. As a result, the liquid level in the chamber of the air separator decreases, which in turn increases the amount of air in the chamber. Such a device for separating air bubbles from blood, which is commonly used in dialysis units, is disclosed in WO 2008 / 53 287 A1. The blood in the separator flows upwards against the force of gravity via a vortex generator, causing the air bubbles to accumulate in the area around the central axis of the separator device. At the upper end of the separator device, the air bubbles are extracted by the vacuum generated by the gas trap.

[0006] DE 196 17 036 C2 also discloses a device for separating air bubbles from blood, wherein a flow guide element is arranged in the region of the inlet nozzle of the separator device. The flow guide element generates a vortex that pushes the blood outwards, so that the air bubbles remain in the center of the separator device and can be separated.

[0007] However, conventional air separators are particularly suitable for separating (micro)bubbles at low blood flow rates. At higher blood flow rates, the residence time in the air separator is insufficient to allow the bubbles to rise or accumulate in the center. The resulting vortex effect often exists and supports separation. Furthermore, a disadvantage of conventional air separators is that they separate not only air but also the air-blood mixture.

[0008] Public Overview

[0009] The aim and purpose of the present disclosure is to overcome or at least reduce the disadvantages of the prior art and in particular to provide a blood circuit system for an extracorporeal blood treatment machine which ensures an improved process of separation of microbubbles from air and thereby eliminates or reduces possible hazards to the patient.

[0010] These aims and objects are solved by a universal blood circuit system for an extracorporeal blood treatment machine according to the subject matter of claim 1 of the present disclosure.

[0011] Therefore, according to the present disclosure, a blood circuit system for an extracorporeal blood treatment machine is configured / adapted to have a branch line or a recirculation line that connects the dynamic bubble trap, preferably directly to the air separator, so that a portion of the blood that flows into the bubble trap is returned upstream of the bubble trap in the blood circuit system. In other words, after flowing from the upstream of the bubble trap into the bubble trap, passing through the recirculation line and the air separator, the blood partially flows back to the arterial line portion or the venous line portion.

[0012] Advantageous embodiments are claimed in the dependent claims and are explained below.

[0013] According to the present disclosure, a bubble trap can be arranged in a venous line section so that microbubbles that are harmful to health and formed when flowing through a dialysis unit can be effectively separated from blood purified in the dialysis unit before entering the patient's body.

[0014] In a preferred embodiment, the bubble trap's recirculation line can be fluidically connected to the arterial line section via an air separator. That is, the recirculation line is directly connected to the arterial line section, and the air separator is inserted into the recirculation line. Alternatively, it is conceivable that the recirculation line is fluidically connected to an air separator disposed within the arterial line section. This means that in this case, the air separator disposed within the arterial line section has two blood supply connections: one for the arterial line section and one for the recirculation line, as well as a blood drain connection for the arterial line section.

[0015] In both variants, it is advantageous that no additional conveying means are required in addition to the conveying means already included in the system to obtain a flow of the fluid / blood / air-blood mixture from the bubble trap through the recirculation line into the arterial line section. Since the blood pump is already arranged in the blood line, a pressure difference is formed between the arterial line section and the venous line section, which results in a flow in the recirculation line without the need for a separate conveying means, and thus low costs. In order to obtain adequate degassing performance, a recirculation rate (i.e. the ratio of the blood flow in the recirculation line to the blood flow in the blood circuit system) of 5-10% is necessary, which determines the structural / geometric design of the recirculation line. For example, the diameter of the recirculation line can be varied relative to its length to set the desired recirculation rate.

[0016] Alternatively, in another preferred embodiment, the recirculation line can connect the bubble trap to the section of the venous line upstream of the bubble trap, i.e., between the dialysis unit and the bubble trap, via an air separator. This improves the degassing performance of the bubble trap because the recirculated blood does not flow through the dialysis unit again, and thus no new microbubbles are formed in the recirculated blood. Furthermore, in this further preferred embodiment, a higher recirculation rate, in particular greater than 10%, can be selected, which in turn improves the degassing performance of the blood trap. Due to the recirculation through the recirculation line, the blood flow in the dynamic bubble trap is increased relative to the blood flow arranged at the blood pump, which also has a positive impact on the degassing performance of the dynamic bubble trap.

[0017] The present disclosure also relates to an extracorporeal blood treatment machine having a blood pump, into which a circuit system according to one of the aforementioned aspects can be inserted to transport blood from a patient to a dialysis unit via a venous line portion and an arterial line portion during operation of the blood pump, and from the dialysis unit back to the patient. According to the present disclosure, the recirculation line of the circuit system partially returns the blood upstream of the bubble trap of the circuit system after the blood has flowed into the bubble trap.

[0018] In an advantageous embodiment, the recirculation line can be inserted / looped into an additional second (peristaltic) blood pump, which decouples the blood flow in the recirculation line from that in the arterial or venous line sections. This means that the pressure conditions in the recirculation line can be individually and very precisely adjusted to the pressure conditions in the arterial and venous line sections. In other words, the blood flow in the recirculation line can be regulated / controlled by the second blood pump, and the blood flow in the venous and arterial line sections can be regulated / controlled by the blood pump of the extracorporeal blood treatment machine.

[0019] Furthermore, according to the present disclosure, it is conceivable to arrange a (safety) air detector (SAD), preferably designed as an ultrasonic sensor, downstream of the bubble trap. The air detector can be designed to determine the blood flow rate. In addition to or as an alternative to the air detector, at least one pressure sensor for determining the blood flow rate can be arranged in the pipeline. According to the present disclosure, the delivery capacity of the blood pump of the extracorporeal blood treatment machine, in particular the rotational speed related to the delivery capacity, can be determined or set based on the blood flow rate determined by the air detector and / or by the at least one pressure sensor. In this way, any blood flow differences can be corrected or compensated. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present disclosure is explained in more detail below with the aid of the accompanying drawings based on preferred configuration examples. As shown below:

[0022] Figure 1 shows a schematic diagram of an extracorporeal blood treatment machine having a blood circuit system according to the present disclosure according to a first configuration example,

[0023] Figure 2 shows a schematic diagram of an extracorporeal blood treatment machine having a blood circuit system according to the present disclosure according to a second configuration example,

[0024] Figure 3 A schematic diagram showing an extracorporeal blood treatment machine having a blood circuit system according to the present disclosure according to a third configuration example, and

[0025] Figure 4 A schematic diagram of an extracorporeal blood treatment machine having a blood circuit system according to the present disclosure according to a fourth configuration example is shown.

[0026] The accompanying drawings are schematic in nature and are intended only to aid understanding of the present disclosure. Similar elements are provided with the same reference numerals. Features of the various configuration examples may be interchanged.

[0027] Detailed description of preferred configuration example

[0028] Figure 1An extracorporeal blood treatment machine 1 according to a first configuration example is schematically shown. The extracorporeal blood treatment machine 1 has an arterial line section 2, through which blood can flow from the patient to a dialysis unit 3. The dialysis unit 3 is preferably configured as a countercurrent dialyzer, in which blood and dialysate flow past each other, separated by a semipermeable membrane. That is, the dialysate flows in a direction opposite to the direction of blood flow ( Figure 1 Arterial line section 2 is a dialysis unit that receives blood from the patient (flowing from top to bottom). A peristaltic pump 4 is arranged in arterial line section 2, which, during operation, transports blood from the patient to dialysis unit 3. Furthermore, a venous line section 5 is arranged downstream of dialysis unit 3 in the direction of blood flow, allowing blood purified in dialysis unit 3 to flow back into the patient. According to the present disclosure, arterial line section 2 and venous line section 5 each form part of a blood circuit system or blood line 6.

[0029] Furthermore, a dynamic bubble trap 7 is arranged in the venous line section 5. The dynamic bubble trap 7 is designed such that, for example, a spiral flow-guiding geometry is arranged within a tubular housing. When blood flows into the housing of the bubble trap 7, the flow-guiding geometry generates eddies / vortices in the blood flow. Due to the centrifugal force in the housing, the eddies generated in this manner force the blood radially outward. As a result, microbubbles, which are lighter than the flowing blood, accumulate in the area around the central axis / rotation axis of the housing and coalesce to form large bubbles. If a pressure difference is applied to the recirculation line 8 arranged in this area, the coalesced large bubbles can be separated / expelled through this recirculation line 8.

[0030] To provide this pressure differential, in the first configuration example, the recirculation line 8 is connected to the arterial line section 2. Specifically, in the first configuration example, the recirculation line 8 is connected to the arterial line section 2 upstream of the blood pump 4. That is, the pressure differential generated by the blood pump 4 between the arterial line section 2 and the venous line section 5 serves as the pressure differential for bubble separation. The recirculation rate—that is, the blood flow rate in the recirculation line 8 relative to the blood flow rate in the blood line 6—is essentially determined or set by the pressure differential applied to the recirculation line 8. To achieve adequate degassing performance, a recirculation rate of approximately 5-10% is necessary. Therefore, this necessary recirculation rate crucially determines the geometric configuration / design of the recirculation line 8. In other words, the diameter of the recirculation line 8 must vary relative to its length in such a way that, depending on the applied pressure differential, a recirculation rate of 5-10% is achieved.

[0031] However, when the bubble trap 7 is used to separate air bubbles, not only the air bubbles flow into the recirculation line 8. Instead, the air-blood mixture is drawn into the recirculation line 8 by the pressure difference applied to the recirculation line 8.

[0032] In addition, an air detector 9 is arranged downstream of the bubble trap 7 of the extracorporeal blood treatment machine 1. The air detector 9 is configured as an ultrasonic sensor and monitors the presence of bubbles in the purified blood before it is returned to the patient. In the first exemplary configuration, the air detector 9 is also used to determine / measure blood flow. Based on this measured blood flow, the delivery capacity of the blood pump 4 is set. Specifically, the delivery capacity of the blood pump 4 is set by the rotational speed of the blood pump 4, which is related to the delivery capacity. That is, by measuring the blood flow at the air detector 9 and setting the rotational speed of the blood pump 4, the aforementioned difference between the blood flow supplied to the patient and the blood flow withdrawn from the patient is corrected or compensated, respectively. In other words, the rotational speed of the blood pump 4 is corrected so that the blood flow desired for the blood treatment becomes the effective blood flow. In addition to the blood flow measured by the air detector 9, the pressure value detected in the arterial line portion 2 and / or the venous line portion 5 can be used alternatively or additionally to determine and correct the effective blood flow.

[0033] As from Figure 1 As can be seen, in the first configuration example, the air separator 10 is arranged in the recirculation line 8, which further improves the degassing performance of the extracorporeal blood treatment machine 1. The air-blood mixture flowing in the recirculation line 8 is supplied to the air separator 10, so that large bubbles remaining in the air-blood mixture can be isolated / separated within the air separator 10.

[0034] Figure 2 An extracorporeal blood treatment machine 1 according to a second configuration example is shown. In the description of the extracorporeal blood treatment machine 1 according to this second configuration example, only the points different from the first configuration example are described below.

[0035] As from Figure 2 It can be seen that in the extracorporeal blood treatment machine 1 according to the second configuration example, the air separator 10 is not arranged in the recirculation line 8. Instead, the (existing) arterial air separator 11 is fluidically connected to the recirculation line 8 and the dynamic bubble trap 7 via additional connections.

[0036] As Figure 2 Another variation of the second configuration example shown, Figure 3 An extracorporeal blood treatment machine 1 according to a third configuration example is shown. Here, a second peristaltic blood pump 12 is inserted between the bubble trap 7 and the arterial air separator 11 in the recirculation line 8. Consequently, the pressure difference in the recirculation line 8, and therefore the recirculation rate, can be largely decoupled from the blood flow in the blood line 6 and can be adjusted very precisely and largely independently of it. In other words, the pressure ratio in the recirculation line 8 can be individually adapted to the pressure ratios in the arterial and venous line sections 2 and 5.

[0037] Similarly, in Figure 4In the extracorporeal blood treatment machine 1 according to the fourth configuration example shown, a second blood pump 12 is arranged in the recirculation line 8. However, in the fourth configuration example, the recirculation line 8 is not connected to an arterial air separator. Instead, the air-blood mixture flowing out of the bubble trap 7 into the recirculation line 8 is fed back to the blood line 6 in the venous line section 5 upstream of the bubble trap 7. To separate bubbles remaining in the air-blood mixture, an air separator 10 and a second blood pump 12 are arranged in the recirculation line 8. That is, after passing through the bubble trap 7, the recirculation line 8, and the air separator 10, the recirculated air-blood mixture returns to the venous line section 5 upstream of the bubble trap 7. Any bubbles remaining in the recirculated air-blood mixture are then resupplied to the bubble trap 7, resulting in higher degassing performance of the bubble trap 7. In other words, in the fourth configuration example, the recirculation line 8 connects the bubble trap 7 to the venous line section 5 upstream of the bubble trap 7, i.e., between the dialysis unit 3 and the bubble trap 7. In this case, the air separator 10 and the second blood pump 12 are arranged in the recirculation line 8 , so that the recirculation rate in the recirculation line 8 is determined by the second blood pump 12 .

[0038] The fact that the air-blood mixture in the fourth configuration example is resupplied to the bubble trap 7 without flowing through the dialysis unit 3 further improves degassing performance without causing additional purification losses in the dialysis unit 3. In this case, the recirculation rate can be selected to be higher than in other configuration examples, in particular, greater than 10%, because there is no loss of purification effect. As the recirculation rate increases, the degassing performance of the bubble trap 7 improves because the vorticity of the vortex generated in the bubble trap 7 increases at higher mass flow rates (blood flow rates), and thus the microbubbles are separated more effectively.

Claims

1. A blood circuit system (6) for an extracorporeal blood treatment machine (1), comprising an arterial line section (2), a venous line section (5), a dynamic bubble trap (7) and an air separator, wherein the blood circuit system (6) is designed to conduct blood from a patient to a dialysis unit (3) and from the dialysis unit (3) to the patient during operation of a blood pump (4) of the extracorporeal blood treatment machine (1), The dynamic bubble trap (7) comprises a housing and a flow guiding geometry arranged in the housing, wherein the flow guiding geometry generates a vortex when blood flows into the housing so as to force the blood radially outward due to the centrifugal force in the housing, wherein a recirculation line or branch line (8) connects the bubble trap (7) to the air separator so as to return part of the blood flowing into the bubble trap (7) to the upstream of the trap (7) in the blood circuit system (6), It is characterized by: The recirculation line or branch line (8) fluidly connects the bubble trap (7) to the arterial line portion (2) via the air separator, or the recirculation line or branch line (8) fluidly connects the bubble trap (7) to the venous line portion (5) via the air separator.

2. The blood circuit system (6) according to claim 1, It is characterized by: The bubble trap (7) is arranged in the venous line section (5).

3. The blood circuit system (6) according to claim 1, It is characterized by: In case the recirculation line or branch line fluidly connects the dynamic bubble trap to the arterial line portion via the air separator, the recirculation line or branch line (8) is fluidly connected to the air separator arranged in the arterial line portion (2).

4. An extracorporeal blood treatment machine (1) having a blood pump (4), into which a blood circuit system (6) according to any of the preceding claims 1 to 3 can be inserted in order to convey blood from a patient to a dialysis unit (3) and from the dialysis unit (3) back to the patient during operation of the blood pump (4), via the arterial line section (2) and the venous line section (5). It is characterized by: The recirculation line or branch line (8) returns part of the blood to the upstream of the bubble trap (7) of the blood circuit system (6) after the blood flows into the bubble trap (7).

5. The extracorporeal blood treatment machine (1) according to claim 4, It is characterized by: The recirculation line or branch line (8) is inserted into an additional blood pump (12).

6. The extracorporeal blood treatment machine (1) according to claim 4, It is characterized by: The air detector (9) is arranged downstream of the bubble trap (7) and is designed to determine the blood flow rate.

7. The extracorporeal blood treatment machine (1) according to claim 6, It is characterized by: At least one pressure sensor for determining the blood flow is arranged in the line.

8. The extracorporeal blood treatment machine (1) according to claim 6, It is characterized by: The delivery capacity of the blood pump (4) is determined based on the blood flow rate determined in the air detector (9).

9. The extracorporeal blood treatment machine (1) according to claim 7, It is characterized by: The delivery capacity of the blood pump (4) is determined based on the blood flow determined in at least one pressure sensor.

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