Air removal device for extracorporeal blood processing

Abstract

The present disclosure relates to a blood circuit system (6) for an extracorporeal blood treatment device (1), comprising an arterial line section (2), a venous line section (5), a dynamic bubble trap (7), and air separators (10, 11), the blood circuit system (6) being 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 device (1), and comprising a recirculation or branch line (8) connected to the bubble trap (7) for returning a portion of the blood flowing into the bubble trap (7) to the blood circuit system (6). The present disclosure also relates to an extracorporeal blood treatment device (1) comprising the blood circuit 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 device, comprising an arterial line section, a venous line section, a dynamic bubble trap, and an air separator, the circuit system 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 device. [Background technology]

[0002] During blood processing, particularly hemodialysis, in conventional blood processing devices, the blood flowing through the dialysis unit for purification becomes infused with microbubbles, which can flow back to the patient without causing an alarm. These microbubbles can deposit in the patient's lungs, flow through the pulmonary capillaries, and be distributed throughout the body via arteries, potentially causing organ damage. Because the formation of microbubbles in the flow through the hemodialysis unit is a common side effect of hemodialysis, it is necessary to separate the microbubbles from the blood before returning it to the patient.

[0003] Dynamic bubble traps (DBTs) for use in heart-lung machines are known, where the dynamic bubble traps are used to filter out microbubbles at high blood flow / blood volume / blood mass flow rates. For example, U.S. Patent No. 6,478,962 B1 discloses a conventional dynamic bubble trap designed for use in a heart-lung machine. The bubble trap accelerates blood radially as it flows through the trap, causing lighter microbubbles to move to a region around the central axis of the bubble trap, while heavier blood components are pushed radially outward by centrifugal force. The microbubble-laden blood that accumulates in the area around the central axis is separated from and returned to the main blood flow.

[0004] This is not the case with conventional air separators / gas traps / blood traps used in dialysis units. Depending on the direction / orientation of the air separator, the air bubbles move toward the center or upward against gravity, where they can eventually be extracted. This means that the air bubbles essentially separate solely due to the density difference between the air bubbles and the blood. As a result, the level in the air separator chamber decreases, which in turn increases the amount of air in the chamber. Such a device for separating air bubbles and blood, conventionally used in dialysis units, is disclosed in WO 2008 / 53287 A1. The blood inside the separator flows upward against gravity through a vortex generator, resulting in the air bubbles collecting in an area around the central axis of the separator device. At the top of the separator device, the air bubbles are extracted by a vacuum generated by a gas trap.

[0005] DE 19617036 C2 also shows a device for separating gas bubbles from blood, in which a flow guide element is arranged in the area of ​​the inlet nozzle of the separator device, which creates a vortex that pushes the blood outwards so that the gas bubbles remain in the centre of the separator device and can be separated.

[0006] However, conventional air separators separate (micro)gas bubbles particularly well at low blood flows. At higher blood flows, the residence time in the air separator is insufficient, and the bubbles do not have enough time to rise or accumulate in the center. The generated vortex effect is usually present and supports the separation. Furthermore, conventional air separators have the disadvantage of separating not only air but also air-blood mixtures. Summary of the Invention

[0007] The purpose and goal of the present disclosure is to overcome or at least reduce the drawbacks of the prior art, in particular to provide a blood circuit system for an extracorporeal blood treatment device that ensures an improved process of air separation of microbubbles, thereby eliminating or reducing possible risks to the patient.

[0008] Said objects and aims are solved for a general blood circuit system for an extracorporeal blood treatment device according to the present disclosure by the subject matter of claim 1.

[0009] Thus, a blood circuit system for an extracorporeal blood treatment device is configured / adapted in accordance with the present disclosure to have a branch line or recirculation line connecting the dynamic bubble trap to an air separator, preferably directly, in order to return a portion of the blood entering the bubble trap to the blood circuit system upstream of the bubble trap. In other words, after entering the bubble trap through the recirculation line and the air separator upstream of the bubble trap, the blood partially flows back into the arterial or venous line portion.

[0010] Advantageous embodiments are claimed in the dependent claims and are described below.

[0011] According to the present disclosure, a bubble trap can be placed in the venous line so that microbubbles, which are harmful to health and which form as the blood flows through the dialysis unit, can be effectively separated from the purified blood in the dialysis unit before it enters the patient.

[0012] In a preferred embodiment, the recirculation line of the bubble trap can be fluidly connected to the arterial line section via an air separator. That is, the recirculation line is directly connected to the arterial line section, with the air separator interposed in the recirculation line. Alternatively, it can be envisaged that the recirculation line is fluidly connected to an air separator arranged in the arterial line section. In this case, this means that the air separator arranged in the arterial line section has two blood supply connections, one for the arterial line section and one for the recirculation line, and a blood discharge connection for the arterial line section.

[0013] In both variants, the flow of the fluid / blood / air-blood mixture from the bubble trap through the recirculation line to the arterial line section is advantageously achieved without the need for additional transport means in addition to those already included in the system. The blood pump already installed in the blood line creates a pressure difference between the arterial and venous line sections, which generates flow in the recirculation line without a separate transport means, thus reducing costs. For sufficient degassing performance, a recirculation rate of 5-10%—i.e., the ratio between the blood flow rate in the recirculation line and the blood flow rate in the blood circuit system—is required, which determines the structure and geometric design of the recirculation line. For example, the diameter of the recirculation line can be varied relative to its length to achieve the desired recirculation rate.

[0014] Alternatively, in another preferred embodiment, the recirculation line can fluidly connect the bubble trap to a venous line section upstream of the bubble trap, i.e., between the dialysis unit and the bubble trap, via an air separator, which leads to an increase in the degassing performance of the bubble trap. This is because the recirculated blood does not flow through the dialysis unit again, and therefore new microbubbles are not formed in the recirculated blood. In addition, in this further preferred embodiment, the recirculation rate can be selected to be high, particularly above 10%, which then improves the degassing performance of the blood trap. Due to recirculation through the recirculation line, the blood flow rate at the dynamic bubble trap is increased compared to the blood flow rate set by the blood pump, which also has a positive effect on the degassing performance of the dynamic bubble trap.

[0015] The present disclosure further relates to an extracorporeal blood treatment device having a blood pump, in which a circuit system according to one of the above-mentioned aspects can be inserted to pump blood from a patient to a dialysis unit and from the dialysis unit back to the patient via an arterial line portion and a venous line portion during operation of the blood pump. According to the present disclosure, a recirculation line of the circuit system partially returns blood to the circuit system upstream of the bubble trap after the blood has flowed into the bubble trap.

[0016] In an advantageous embodiment, the recirculation line can be inserted / looped to an additional second (peristaltic) blood pump, which results in separating the blood flow rate in the recirculation line from the blood flow rate in the arterial or venous line sections. This means that the pressure conditions in the recirculation line can be adjusted very precisely, independently of the pressure conditions in the arterial and venous line sections. In other words, the blood flow rate in the recirculation line can be adjusted / controlled by the second blood pump, and the blood flow rates in the arterial and venous line sections can be adjusted / controlled by the blood pump of the extracorporeal blood treatment device.

[0017] Furthermore, the present disclosure envisages that a (safety) air detector (SAD), preferably designed as an ultrasonic sensor, is arranged downstream of the bubble trap. The air detector may 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 may be arranged in the line. According to the present disclosure, the transport capacity of the blood pump of the extracorporeal blood treatment device, in particular the rotational speed, which correlates with the transport capacity, may be determined or set based on the blood flow rate determined by the air detector and / or the at least one pressure sensor. In this way, possible differences in blood flow rate may be corrected or compensated for. [Brief explanation of the drawings]

[0018] The present disclosure will be explained in more detail below with the aid of figures based on preferred configuration examples.

[0019] [Figure 1] 1 shows a schematic diagram of an extracorporeal blood treatment device having a blood circuit system according to the present disclosure in a first configuration example. [Figure 2] 1 shows a schematic diagram of an extracorporeal blood treatment device having a blood circuit system according to a second configuration example of the present disclosure. [Figure 3] 10 shows a schematic diagram of an extracorporeal blood treatment device having a blood circuit system according to the present disclosure in a third configuration example. [Figure 4] 10 shows a schematic diagram of an extracorporeal blood treatment device having a blood circuit system according to the present disclosure in a fourth configuration example.

[0020] The figures are schematic in nature and are intended merely to aid in the understanding of the present disclosure. Identical elements are provided with the same reference numerals. Features of the various implementations may be interchanged.

[0021] (Detailed description of preferred configuration examples) FIG. 1 shows a schematic diagram of a first exemplary extracorporeal blood treatment device 1. The device 1 has an arterial line 2 through which blood can flow from a patient to a dialysis unit 3. The dialysis unit 3 is preferably configured as a counterflow dialyzer, in which blood and dialysate flow past each other, separated by a semipermeable membrane. That is, the dialysate flows through the dialyzer in the opposite direction to the blood flow (from top to bottom in FIG. 1 ). A blood pump 4 in the form of a peristaltic pump is disposed in the arterial line 2, which pumps blood from the patient to the dialysis unit 3 during operation. Furthermore, a venous line 5 is disposed downstream of the dialysis unit 3 in the blood flow direction, so that blood purified in the dialysis unit 3 flows back to the patient. According to the present disclosure, the arterial line 2 and the venous line 5 each form part of a blood circuit system or blood line 6.

[0022] Furthermore, a dynamic bubble trap 7 is disposed in the venous line section 5. The dynamic bubble trap 7 is designed, for example, with a spiral flow guide shape disposed inside a tubular housing. When blood flows into the housing of the bubble trap 7, the flow guide shape generates vortices / vortexes in the blood flow. The vortices thus generated push the blood radially outward within the housing due to centrifugal force. Therefore, microbubbles, which are lighter than the flowing blood, accumulate in the area around the central axis / axis of rotation of the housing and coalesce to form macrobubbles. When a pressure difference is applied to a recirculation line 8 disposed in this area, the coalesced macrobubbles can be separated / discharged through the recirculation line 8.

[0023] To provide this pressure difference, the recirculation line 8 is connected to the arterial line section 2 in the first configuration example. Specifically, the recirculation line 8 in the first configuration example is connected to the arterial line section 2 upstream of the blood pump 4. That is, the pressure difference generated between the arterial and venous line sections 2, 5 by the blood pump 4 is used as the pressure difference used for bubble separation. The recirculation rate, i.e., 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 difference applied to the recirculation line 8. For sufficient degassing performance, a recirculation rate of approximately 5-10% is required. Therefore, the required recirculation rate critically determines the geometry / design of the recirculation line 8. In other words, the diameter of the recirculation line 8 needs to be changed relative to its length depending on the applied pressure difference so that the recirculation rate is 5-10%.

[0024] However, when bubble trap 7 is used to separate air bubbles, it is not just air bubbles that enter recirculation line 8. Rather, the pressure differential applied to recirculation line 8 causes the air-blood mixture to be drawn into recirculation line 8.

[0025] Furthermore, an air detector 9 is disposed in the extracorporeal blood treatment device 1 downstream of the bubble trap 7. This air detector 9 is configured as an ultrasonic sensor and monitors the presence of air bubbles in the purified blood before the purified blood is returned to the patient. In the first configuration example, the air detector 9 is also used to determine / measure the blood flow rate. Based on this measured blood flow rate, the transport capacity of the blood pump 4 is set. In particular, the transport capacity of the blood pump 4 is set via the rotational speed of the blood pump 4, which correlates with the transport capacity. That is, by measuring the blood flow rate with the air detector 9 and setting the rotational speed of the blood pump 4, a correction or compensation is made for the difference between the blood flow rate delivered to the patient and the blood flow rate withdrawn from the patient. In other words, the rotational speed of the blood pump 4 is corrected so that the effective blood flow rate desired for blood treatment is achieved. In addition to the blood flow rate measured by the air detector 9, alternatively or additionally, pressure values ​​detected in the arterial line section 2 and / or the venous line section 5 can be used to determine and correct the effective blood flow rate.

[0026] 1, in a first configuration example, the air separator 10 is disposed in the recirculation line 8, which further increases the degassing performance of the extracorporeal blood treatment device 1. The air separator 10 is supplied with the air-blood mixture flowing in the recirculation line 8, so that macro-bubbles remaining in the air-blood mixture can be isolated / separated in the air separator 10.

[0027] 2 shows an extracorporeal blood treatment apparatus 1 according to a second configuration example. In the description of the extracorporeal blood treatment apparatus 1 according to this second configuration example, only the differences from the first configuration example will be described below.

[0028] 2, in the extracorporeal blood treatment device 1 according to the second configuration example, the air separator 10 is not located in the recirculation line 8. Rather, the (present) arterial air separator 11 is fluidly connected to the recirculation line 8 and the dynamic bubble trap 7 via an additional connection.

[0029] As a further modification of the second exemplary configuration shown in Fig. 2, Fig. 3 shows an extracorporeal blood treatment device 1 according to a third exemplary configuration, in which a second peristaltic blood pump 12 is interposed in the recirculation line 8 between the bubble trap 7 and the arterial air separator 11. The pressure difference across the recirculation line 8, and thus the recirculation rate, can therefore be substantially decoupled from the blood flow in the blood line 6 and can be set very accurately, largely independently of said blood flow. 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, 5.

[0030] Similarly, in the extracorporeal blood treatment device 1 according to the fourth configuration shown in FIG. 4 , the second blood pump 12 is disposed in the recirculation line 8. However, in the fourth configuration, the recirculation line 8 is not connected to an arterial air separator, but rather the air-blood mixture flowing out of the bubble trap 7 and into the recirculation line 8 is returned to the blood line 6 at the venous line section 5 upstream of the bubble trap 7. To separate any remaining air bubbles from the air-blood mixture, the air separator 10 and the second blood pump 12 are disposed in the recirculation line 8. That is, after flowing through the bubble trap 7, the recirculation line 8, and the air separator 10, the recirculated air-blood mixture is returned to the venous line section 5 upstream of the bubble trap 7. As a result, any remaining air bubbles in the recirculated air-blood mixture are again supplied to the bubble trap 7, resulting in improved degassing performance of the bubble trap 7. In other words, in the fourth configuration, 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 .

[0031] The fact that the air-blood mixture in the fourth configuration example does not flow through the dialysis unit 3 but is fed back to the bubble trap 7 further increases the 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 the further configuration examples, in particular more than 10%, since there is no loss of purification effect. With an increased recirculation rate, the vorticity of the vortices generated in the bubble trap 7 increases at higher mass flow rates (blood flow rates), and therefore the microbubbles are separated more effectively, improving the degassing performance of the bubble trap 7. The following items were included in the claims of the original patent application: (Item 1) A blood circuit system (6) for an extracorporeal blood treatment device (1), comprising an arterial line section (2), a venous line section (5), a dynamic bubble trap (7), and air separators (10, 11), the blood circuit system (6) being 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 device (1); A blood circuit system (6), characterized in that a recirculation line or branch line (8) connects the bubble trap (7) to the air separator (10, 11), preferably directly, upstream of the bubble trap (7), in order to return a portion of the blood flowing into the bubble trap (7) to the blood circuit system (6). (Item 2) 2. The blood circuit system (6) according to claim 1, characterized in that the bubble trap (7) is arranged in the venous line section (5). (Item 3) 3. The blood circuit system (6) according to claim 1, wherein the recirculation line (8) fluidly connects the bubble trap (7) to the arterial line section (2) via the air separators (10, 11). (Item 4) 4. The blood circuit system (6) according to claim 3, characterized in that the recirculation line (8) is fluidly connected to the air separator (11) arranged in the arterial line section (2). (Item 5) 3. The blood circuit system (6) according to claim 1, wherein the recirculation line (8) fluidly connects the bubble trap (7) to the venous line section (5) via the air separator (10). (Item 6) An extracorporeal blood treatment device (1) having a blood pump (4), a blood circuit system (6) according to any one of claims 1 to 5, insertable during operation of the blood pump (4) for pumping blood from a patient to a dialysis unit (3) and from the dialysis unit (3) back to the patient via the arterial line portion (2) and the venous line portion (5); The extracorporeal blood treatment device (1) is characterized in that the recirculation line (8) partially returns the blood to the blood circuit system (6) after the blood flows into the bubble trap (7) upstream of the bubble trap (7). (Item 7) 7. An extracorporeal blood treatment device (1) according to claim 6, characterized in that the recirculation line (8) is inserted into an additional blood pump (12). (Item 8) 8. Extracorporeal blood treatment device (1) according to claim 6 or 7, characterized in that an air detector (9), preferably designed as an ultrasonic sensor, is arranged downstream of the bubble trap (7) and designed to determine the blood flow rate. (Item 9) 9. Extracorporeal blood treatment device (1) according to any one of claims 6 to 8, characterized in that at least one pressure sensor for determining the blood flow rate is arranged in the line (6). (Item 10) 10. The extracorporeal blood treatment device (1) according to claim 8 or 9, characterized in that the transport capacity of the blood pump (4), in particular the rotational speed correlated with said transport capacity, is determined based on the blood flow rate determined by the air detector (9) and / or the at least one pressure sensor.

Claims

1. A blood circuit system for an extracorporeal blood treatment device, comprising an arterial line section, a venous line section, a dynamic bubble trap, and an air separator, the blood circuit system being 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 device; a recirculation or branch line connects the dynamic bubble trap to the air separator for returning a portion of the blood entering the dynamic bubble trap upstream of the dynamic bubble trap to the blood circuit system; 10. A blood circuit system, comprising: a recirculation line fluidly connecting the dynamic bubble trap to the arterial line portion via the air separator;

2. A blood circuit system for an extracorporeal blood treatment device, comprising an arterial line section, a venous line section, a dynamic bubble trap, and an air separator, the blood circuit system being 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 device; a recirculation or branch line connects the dynamic bubble trap to the air separator for returning a portion of the blood entering the dynamic bubble trap upstream of the dynamic bubble trap to the blood circuit system; 10. A blood circuit system, comprising: a recirculation line fluidly connecting the dynamic bubble trap to the venous line portion via the air separator.

3. 3. The blood circuit system according to claim 1, wherein the dynamic bubble trap is disposed in the venous line section.

4. 2. The blood circuit system according to claim 1, wherein the recirculation line is fluidly connected to the air separator disposed in the arterial line section.

5. 1. An extracorporeal blood treatment device having a blood pump, comprising:

5. A blood circuit system according to claim 1, wherein the blood circuit system is insertable to pump blood from a patient to a dialysis unit and from the dialysis unit back to the patient via the arterial line portion and the venous line portion during operation of the blood pump; The extracorporeal blood treatment device, characterized in that the recirculation line partially returns the blood to the blood circuit system after the blood enters the dynamic bubble trap upstream of the dynamic bubble trap.

6. 6. The extracorporeal blood treatment device according to claim 5, wherein an additional blood pump is arranged in the recirculation line.

7. 7. An extracorporeal blood treatment device according to claim 5, wherein an air detector is arranged downstream of the dynamic bubble trap and is designed to determine the blood flow rate.

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