Device and method for air-free filling of a fluid management system

Description

Technical field

[0001] The invention relates to a device and a method for air-free filling of the hydraulics of a fluid management system, e.g., a dialysis machine. background

[0002] Modern dialysis machines for chronic hemodialysis prepare the required dialysis solution online in an internal hydraulic system. This internal hydraulic system pumps the dialysis solution into the machine's external extracorporeal blood line system, and the used dialysate from the blood line system is collected by this hydraulic system and directed to the drain.

[0003] D1 describes such a machine-external extracorporeal blood line system, which has at least two filter devices. After coupling to a medical blood treatment device, the blood line system can be filled with process fluid.

[0004] D2 also concerns a method for filling the machine-external extracorporeal blood line system with dialysate. Using pressure pulses, air bubbles on the blood side of the dialyzer are released and subsequently transported away.

[0005] D3 relates to a system and method for cleaning and disinfecting a treatment system, in particular for home dialysis.

[0006] D4 concerns the use of an anticoagulant to prime a tubing system during the collection and separation of blood components.

[0007] D5 covers various aspects of extracorporeal blood tubing systems.

[0008] To ensure the hygiene of the system, regular disinfection of this machine-internal hydraulic system is necessary.

[0009] Especially if the hydraulic system is filled with air prior to disinfection, complete air removal must be ensured when filling the hydraulic system with fluid to ensure complete wetting of the surfaces with disinfectant. This also ensures heat conduction to the seal during hot disinfection and complete rinsing of the disinfectant after disinfection.

[0010] When simply filling the hydraulic system with a steady flow of the rinsing solution, hydraulic components cannot be filled air-free, especially if their geometry impedes the removal of gas bubbles by the rinsing solution. The same applies to chambers and cavities with a geometry that causes the rising bubbles to be located outside the fluid flow. An example of such a special geometry is a constriction of the flow cross-section of the fluid lines in the hydraulic system, e.g., a coupling point for the hose set of an extracorporeal blood circuit, especially the online port.

[0011] The object of the present invention is to provide a fluid management system, in particular a hydraulic system of a blood treatment machine for renal replacement therapy, and a method for flushing the fluid management system, which ensure bubble-free filling of the machine's internal fluid lines. Summary of the invention

[0012] According to the teaching of the present invention, this object is achieved by a device according to claim 1 and a method according to claim 14. Particular embodiments are the subject of the dependent claims.

[0013] The invention relates to a fluid management system. Such a fluid management system can, for example, be the hydraulic system of the dialysis machine, which serves to produce and / or deliver the dialysis solution. The fluid management system has a machine-internal fluid line (as a machine component) with a fluid inlet for connection to a supply of a rinsing fluid and a fluid outlet for connection to a line for draining the rinsing fluid.

[0014] According to the claim, "machine-internal" can mean that the fluid line is arranged entirely within the machine in one embodiment. Likewise, in another embodiment, a machine-internal fluid line also includes a fluid line that is only partially routed within the machine.

[0015] A shut-off device is arranged in the fluid line, which divides the fluid line into a first and a second fluid line section.

[0016] The first fluid line section has a first fluid conveying means which, when operated according to the invention, is arranged upstream of the shut-off device.

[0017] The second fluid line section has a second fluid conveying means which, when operated according to the invention, is arranged downstream of the shut-off device.

[0018] The fluid management system comprises a control device for controlling the shut-off device, the first fluid conveying means, and the second fluid conveying means, wherein the control device is configured to increase a pressure in the first fluid line section upstream of the shut-off device by controlling the first fluid conveying means to convey fluid in the direction of the shut-off device, and is configured to reduce a pressure in a second fluid line section of the fluid line system downstream of the shut-off device by controlling the second fluid conveying means to convey fluid away from the shut-off device, and wherein the control device is configured to open the shut-off means at least once when the pressure in the first fluid section is increased and when the pressure in the second fluid section is reduced.

[0019] The control device can comprise a processor, a data storage medium, and data lines. A program code can be stored on the storage medium, and when executed, corresponding signals are sent to the respective components.

[0020] It is also possible to alternately open and close the shut-off device repeatedly, e.g., 3 to 7 times. Repeated opening and closing may allow for a more complete or even complete removal of all air bubbles in the fluid line section.

[0021] The fluid line section can be closed to form a recirculation circuit, thereby reducing the consumption of rinsing solution. In order to remove air from the recirculation circuit, an air separation means can be arranged in the first or, preferably, the second fluid line section. The air separation means can be arranged downstream of the shut-off means. A chamber with an inlet and an outlet and a third opening in the upper region of the chamber for removing air from the chamber can be used as such an air separation means. The air separation means can also be a connection to the outside with a pump, whereby the liquid, including the bubbles, is pumped out of the fluid section. A water inlet chamber in the inlet of the fluid management system or a chamber in the outlet of the fluid management system can be used as an air separation chamber, for example.By recirculating, at higher flows one is no longer dependent on a high supply volume from the water source.

[0022] The fluid line, in particular the second fluid line section, can have at least one constriction of the passage lumen. Air bubbles cannot pass through, or can only pass through with difficulty, particularly in areas where the passage lumen of the fluid line is constricted.

[0023] Such constrictions can be found, for example, at the hydraulic coupling points for the extracorporeal blood circulation. Such coupling points are used to pump dialysate directly into the patient's blood, for example. This is referred to as a substitution port. Another coupling point, the flushing port, is used as a patient connection point for filling and flushing the tubing set before treatment begins. Effective disinfection is particularly important here, as there is direct contact between the hydraulic system and the extracorporeal blood circulation.

[0024] For optimal removal of air bubbles at such constrictions, the shut-off device can be positioned upstream of this constriction and the second fluid conveying device downstream of this constriction. When the shut-off device is closed, a negative pressure develops between the shut-off device and the second fluid conveying device when the second fluid conveying device is operating. This negative pressure initially increases the volume of gas bubbles located in this area. At the same time, operating the first fluid conveying device upstream of the shut-off device can increase the pressure in the fluid line upstream of the closed shut-off device.

[0025] Once a pressure difference has built up between the fluid line sections upstream and downstream of the shut-off device, the pressure largely equalizes when the shut-off device is opened, resulting in a pressure surge downstream of the shut-off device. This generates a pressure surge that divides the gas bubbles, enlarged and destabilized by the negative pressure, into smaller microbubbles. These gas bubbles can more easily pass through the constrictions in the fluid line section. Due to the negative pressure and the flow peak in the fluid line section downstream of the shut-off device, these small bubbles are then drawn through the constriction before they reassemble into a larger bubble, which can then be removed from the fluid line system.

[0026] This effect is particularly effective when the compliance of the fluid line between the shut-off device and the constriction of the passage lumen is as small as possible, e.g. 0.5 to 50 cm, preferably 10-30 cm.

[0027] To ensure that a sufficient pressure difference exists when the shut-off device opens, the fluid management system can have pressure measuring means, and the control device can be configured to control the opening or the alternating opening and closing of the shut-off device via the pressure values ​​in the internal fluid line section determined by the pressure measuring means. In particular, a pressure measuring means is arranged in fluid communication with the first fluid line section and a second pressure measuring means is arranged in fluid communication with the second fluid line section.

[0028] A sufficient pressure difference is achieved, for example, when the difference is between 1000 and 3000 hPa, preferably between 1600 and 2500 hPa.

[0029] The fluid management system may alternatively or additionally comprise a timing device. The control device may then be configured to control the opening or the alternating opening and closing of the shut-off device over the times determined by this timing device. Achieving a sufficient pressure differential, with known pump flow rates, can also be ensured by the duration of the phases before the shut-off device opens, or the duration of the phase before the shut-off device opens and the duration of the shut-off device opening.

[0030] The shut-off device can be closed for 1-5 seconds, preferably 2 seconds.

[0031] The opening of the shut-off device can take place for 2-6 seconds, preferably 4 seconds.

[0032] In addition, the valve can be opened quickly, allowing pressure equalization to occur within a time interval of between 20 and 500 ms, preferably between 20 and 60 ms. This allows gas bubbles to be transported particularly effectively.

[0033] The control device may alternatively be configured to control the opening or the alternating opening and closing of the shut-off device as a function of a certain number of working cycles of at least one fluid conveying means when, for example, diaphragm pumps or a balancing chamber timing system are used as pumping means.

[0034] The shut-off means can be any means suitable for separating the fluid line sections from one another in such a way that a required pressure difference is created. The shut-off means can preferably be a valve, e.g., an electromagnetic valve or a pinch valve.

[0035] The fluid management system can utilize any type of fluid conveying means suitable for generating the required overpressure or negative pressure to convey the rinsing fluid. The fluid conveying means can preferably be a pump, e.g., peristaltic pumps, diaphragm pumps, or, particularly preferably, gear pumps.

[0036] The fluid management system can, for example, be part of the hydraulic system of a blood treatment machine for renal replacement therapy, e.g., a hemodialysis machine. In the hydraulic system of such a blood treatment machine, the degassing pump can, for example, be the first fluid delivery means for building up positive pressure, and the flow pump can be the second fluid delivery means for generating negative pressure. Both pumps can be gear pumps.

[0037] The invention also relates to a method for the bubble-free filling of a fluid management system according to the invention with a rinsing liquid, wherein the method consists in filling the system with a rinsing liquid by operating the first and / or the second fluid conveying means. During the filling of the fluid line, the shut-off means is open. After filling the fluid line, the system can first be flushed for a certain period of time, e.g. 5-60 seconds, by operating the first and / or the second fluid conveying means. In the next step, the shut-off device is closed. To increase the pressure in the first fluid line section and / or reduce the pressure in the second fluid line section, at least one of the fluid conveying means continues to be operated. The delivery of the fluid can also be interrupted. After the shut-off means is closed, at least one is then operated so that a pressure difference can develop.After a pressure difference has developed, the shut-off device is opened.

[0038] The shut-off device can be closed and opened several times, preferably 3 to 9 times.

[0039] For optimal removal of air bubbles, the shut-off device can be opened while at least the second fluid conveying device is operating.

[0040] Further details and advantages of the invention are described in more detail with reference to the embodiments shown in the drawings. Brief description of the drawings

[0041] Figure 1 shows a schematic representation of a fluid management system according to the invention. Figure 2 shows an embodiment of a method described here using a schematic representation. Detailed description of an embodiment

[0042] In Figure 1A part of the hydraulics of a dialysis machine is shown schematically, as an example of a fluid management system.

[0043] The rinsing agent source 14 initially supplies a rinsing solution to the water inlet chamber 10. To fill the hydraulics, the flow pump 2 directs the rinsing solution into the first fluid section 15, through the degassing pump 1 and the degassing chamber 9, into the fresh water chamber of the left balancing chamber 8, and through the shut-off device 4 into the second fluid section 16. From there, the rinsing solution is directed via the wastewater side of the right balancing chamber 8' back into the water inlet chamber 10 with an aeration means 17. In the first fluid section 15, a pressure measuring device 5 is arranged upstream of the shut-off device 4. In the second fluid section 16, a pressure measuring device 6 is arranged downstream of the shut-off device 4. In addition, the second fluid section 16 contains a coupling point 7 for an extracorporeal blood tubing system.

[0044] This coupling point 7 is located at the front of the machine. After coupling to the extracorporeal blood tubing system, dialysate can be delivered directly from the hydraulics into the extracorporeal blood circuit. To enable complete disinfection of this coupling point, it has a coaxial design with an inner tube and an outer tube arranged coaxially around it. The inner tube is set back from the outer tube. In flushing or disinfection mode, the outer tube is sealed to the outside by a flap. In flushing or disinfection mode, the flushing or disinfection solution flows through the inner tube into the outer tube arranged coaxially around it and from there into a drain line. The distance between the inner and outer tubes is 6 mm.In addition, the coupling point 7 is inclined along its longitudinal axis so that the liquid outlet is positioned lower than the outlet of the inner tube, in order to facilitate complete emptying of the port of liquid. Therefore, air bubbles can become trapped in front of the recessed inner tube and cannot easily be transported into the drain in flushing mode with laminar flow through this narrow gap in the outer tube against the buoyancy force. This narrow point, which forms the connection point to the hose system and thus to a potentially infectious medium, would then not be fully accessible to a disinfectant solution. Air-free filling also optimizes heat transfer through the liquid disinfectant to the seal of the flap and the complete flushing out of the disinfectant solution after disinfection is complete.

[0045] To achieve complete removal of air bubbles, the dialysis machine includes a control unit 3. This control unit 3 is configured to fill and then circulate the fluid sections 15 and 16 by operating the flow pump 2 with a continuous flow.

[0046] Then, with the flow pump 2 and the degassing pump 1 operating simultaneously, the shut-off device 7 is closed. Overpressure is built up in the first fluid section 15, while a negative pressure develops in the second fluid section 16. Air bubbles that have not passed through a constriction of the passage lumen in the second fluid section 16 during flushing initially expand in the negative pressure. As soon as the pressure measuring devices 5 and 6 detect a sufficient pressure difference between the first 15 and second fluid sections 16, the shut-off device 4 is opened, causing pressure equalization. The pressure surge in the second fluid section 16 breaks the air bubbles into smaller gas bubbles. These are then immediately pumped through the constriction by the degassing pump and then enter the water inlet chamber 10, where they are discharged into the atmosphere.If the fluid level in the water inlet chamber falls below a specified value, it is filled with rinsing solution.

[0047] If degassing is to be avoided during high flow phases, the degassing throttle 9 can be bypassed by opening the valve 12.

[0048] The process of alternately closing and opening the shut-off device 7 can be repeated several times, e.g. 7 times.

[0049] Subsequently, fluid conveying devices 1 and 2 are stopped, the system is vented and the valves are closed.

[0050] In Figure 2 a flowchart of an embodiment of the method according to the invention is shown.

[0051] At the start of the dialysis treatment, the outer tube of the coaxial coupling point of the dialysis machine for the extracorporeal blood tubing system and the fluid line leading from it is emptied and is thus filled with air.

[0052] In a first step 101 of the filling process, the Figure 1 The water inlet chamber 10 shown and one compartment of each of the balance chambers are filled with water.

[0053] In a second method step 102, the rinsing solution is Figure 1 The fluid circulates in the fluid circuit shown. Valves 4, 11, and 12 are open. This process step takes approximately 5 seconds.

[0054] In a third process step 103, the coupling point is flushed with a continuous flow. This process step 103 lasts approximately 5 seconds.

[0055] In a fourth process step 104, valve 4 is closed, and by operating degassing pump 1, an overpressure of over 1800 hPa is built upstream of the valve. By operating flow pump 2, a negative pressure of less than -400 hPa is built up downstream of valve 4. This process step lasts approximately 2 seconds.

[0056] In a fifth process step 105, the pressure difference is reduced by opening valve 4 for approximately 4 seconds.

[0057] To completely remove the air, process steps 104 and 105 are then repeated up to seven times.

[0058] In a sixth process step 106, pumps 1 and 2 are stopped and the system is ventilated.

[0059] In a seventh process step 107, the valves used are closed. List of reference symbols:

[0060] First pump 1 Second pump 2 Control unit 3 Shut-off device 4 First pressure measuring device 5 Second pressure measuring device 6 Coupling point for extracorporeal blood tubing system 7 Balancing chambers 8 Degassing chamber 9 Water inlet chamber 10 Valve 11 Valve 12 Fluid management system 13 Flushing agent source 14 First fluid line section 15 Second fluid line section 16 Ventilation device 17

Claims

1. Fluid management system (13) comprising a machine-internal fluid line which can be connected to a fluid inlet for supplying a flushing fluid and a fluid outlet for discharging the flushing fluid, a shut-off device (4) in the fluid line, which divides the fluid line into a first and a second fluid line portion (15, 16), a first fluid conveying means (1) in the first fluid line portion (15) arranged upstream of the shut-off device during operation of the first fluid conveying means (1), a second fluid conveying means (2) in the fluid line portion (16) arranged downstream of the shut-off device (4) during operation of the second fluid conveying means (2), and a control device (3) for actuating the shut-off device (4), the first fluid conveying means (1) and the second fluid conveying means (2), wherein the control device (3) is configured, in order to increase a pressure in the first fluid line portion (4) relative to a pressure in the second fluid line portion (16), to actuate the first fluid conveying means (1) for conveying fluid in the direction of the shut-off device (15), and is configured, in order to lower a pressure in a second fluid line portion (4) relative to the pressure in the first fluid line portion downstream of the shut-off device (4), to actuate the second fluid conveying means (2) for conveying fluid away from the shut-off device (16), and wherein the control device (3) is configured to open the shut-off agent (4) at least once at increased pressure in the first fluid portion (15) and at lowered pressure in the second fluid portion (16).

2. Fluid management system (13) according to Claim 1, wherein the control device (3) is configured to repeatedly close the shut-off means (4) in order to build up a pressure difference between the first and second fluid line portion (15, 16) and to open it in order to equalize the pressure difference.

3. Fluid management system (13) according to Claim 1 or 2, wherein the first and the second fluid line portion (15, 16) are closed to form a recirculation circuit and have an air separator means.

4. Fluid management system (13) according to one of the preceding claims, wherein one of the fluid line portions (15, 16), preferably the second fluid line portion (16) has at least one constriction of the passage lumen and the shut-off means (4) is arranged upstream of and the second pumping means (2) is arranged downstream of the constriction.

5. Fluid management system (13) according to Claim 4, wherein the shut-off means (4) is arranged in the fluid line portion upstream of the constriction of the passage lumen by from 0.5 to 50 cm, preferably 10-30 cm.

6. Fluid management system (13) according to Claim 4, wherein the constriction of the passage lumen is arranged at a connection point for the extracorporeal blood circulation.

7. Fluid management system (13) according to one of the preceding claims, wherein the fluid management system has, at least in one of the first and the second fluid line portions (15, 16), in each case a pressure measuring means (5, 6), and the control device (3) is configured to control the opening or alternately opening and closing of the shut-off device (4) via the pressure values determined by the pressure measuring means (5, 6).

8. Fluid management system (13) according to Claim 7, wherein opening of the shut-off means (4) takes place when a pressure difference between the upstream and downstream fluid line portion (15, 16) of from 1000 to 3000 hPa, preferably of from 1600 to 2500 hPa has been set.

9. Fluid management system (13) according to one of the preceding claims, wherein the fluid management system has a time measuring means, and the control device (3) is configured to control the opening or the alternating opening and closing of the shut-off device (4) via the times determined by the time measuring means.

10. Fluid management system (13) according to one of the preceding claims, wherein the control device (3) is configured to control the opening or the alternating opening and closing of the shut-off device (4) in a manner dependent on a working cycle of at least one of the fluid conveying means (1, 2).

11. Fluid management system (13) according to one of the preceding claims, wherein the shut-off means (4) is a valve, e.g. an electromagnetic valve or a constriction-hose valve.

12. Fluid management system (13) according to one of the preceding claims, wherein the fluid conveying means are pumps, e.g. peristaltic pumps or preferably gear pumps.

13. Fluid management system (13) according to one of the preceding claims, wherein the fluid management system is part of a hydraulic system of a blood treatment machine for renal replacement therapy.

14. Method for flushing a machine-internal fluid management system, preferably according to one of Claims 1 to 13, wherein the method consists of - A) filling a fluid line of the fluid management system with a flushing fluid by operating at least one fluid conveying means (1, 2) while the shut-off device (4) is open, - then - B) closing the shut-off device (4), and - C) building up a pressure difference between the first and second fluid line portions (15, 16) by operating at least one of the fluid conveying means, - D) opening the shut-off device (4).

15. Method according to Claim 14, wherein the method steps B) to D) are repeated several times, preferably 3-7 times.

16. Method according to either of Claims 14 or 15, wherein at least the second fluid conveying means (2) is in operation when the shut-off means (4) is opened.