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

Abstract

The invention relates to a device and a method for filling and flushing the hydraulics of a dialysis machine, whereby a removal of air bubbles from the hydraulics is ensured.

Claims

1. A dialysis machine comprising a machine-internal fluid line that is completely or partially inside the dialysis machine, and a fluid management system that is configured to be connected to a fluid input and a fluid output, the fluid input being configured to form a fluid communication with a supply of a flushing liquid, and the fluid output being configured for discharging the flushing liquid, the fluid management system comprising a locking device in the fluid line, which divides the fluid line into a first fluid line portion and a second fluid line portion, a first fluid conveying means in the first fluid line portion arranged upstream of the locking device, a second fluid conveying means in the second fluid line portion arranged downstream from the locking device, and a control device for controlling the locking device, the first fluid conveying means, and the second fluid conveying means, wherein the control device is configured to control the first fluid conveying means for conveying liquid in the direction of the locking device in order to increase a pressure of liquid in the first fluid line portion relative to a pressure of liquid in the second fluid line portion, and the control device is configured to control the second fluid conveying means for conveying liquid away from the locking device in order to decrease a pressure in the second fluid line portion relative to the pressure in the first fluid line portion, and the control device is configured to open the locking device at least once when the pressure in the first fluid line portion is greater than the pressure in the second fluid line portion.

2. The dialysis machine according to claim 1, wherein the control device is configured to repeatedly close the locking device for building up a pressure difference between the first and second fluid line portion, and to open it to compensate for the pressure difference.

3. The dialysis machine according to claim 1, wherein the first and the second fluid line portion are closed to form a recirculation circuit and the recirculation circuit has an air separating means.

4. The dialysis machine according to claim 1, wherein one of the first fluid line portion and the second fluid line portion has at least one constriction, the locking device is arranged upstream of the constriction, and the second fluid conveying means is arranged downstream from the constriction.

5. The dialysis machine according to claim 4, wherein the locking device is arranged 0.5 to 50 cm upstream of the constriction of the through lumen in the fluid line portion.

6. The dialysis machine according to claim 4, wherein the constriction of the first fluid line portion or the second fluid line portion is arranged in a connection point for connection to an extracorporeal blood circuit.

7. The dialysis machine according to claim 1, wherein the fluid management system further comprises a pressure measuring means in the first fluid line portion, a pressure measuring means in the second fluid line portion, or pressure measuring means in both the first fluid line portion and the second fluid line portion, and the control device is configured to control the opening or the alternating opening and closing of the locking device in response to pressure values determined by the at least one pressure measuring means.

8. The dialysis machine according to claim 7, wherein an opening of the locking device takes place when a pressure difference between the first fluid line portion and the second fluid line portion of from 1000 to 3000, hPa, has been reached.

9. The dialysis machine according to claim 1, wherein the fluid management system has a time measuring means, and the control device is configured to control the opening or the alternating opening and closing of the locking device over the times determined by the time measuring means.

10. The dialysis machine according to claim 1, wherein the control device is configured to control the opening or the alternating opening and closing of the locking device as a function of an operating cycle of at least one of the fluid conveying means.

11. The dialysis machine according to claim 1, wherein the locking device is a valve.

12. The dialysis machine according to claim 1, wherein the fluid conveying means are pumps.

13. The dialysis machine according to claim 1, wherein the dialysis machine is a blood treatment machine for renal replacement therapy.

14. The dialysis machine according to claim 4, wherein the locking device is arranged 10-30 cm upstream of the constriction.

15. The dialysis machine according to claim 7, wherein the fluid management system is configured to open the locking device when a pressure difference between the first fluid line portion and the second fluid line portion reaches a pressure of from 1600 to 2500 hPa.

16. The dialysis machine according to claim 1, wherein the locking device is an electromagnetic valve or a tubing pinch valve.

17. The dialysis machine according to claim 1, wherein each of the first fluid conveying means and the second fluid conveying means is a peristaltic pump or a geared pump.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a schematic illustration of a fluid management system according to the invention.

(2) FIG. 2 shows an exemplary embodiment of a method described here on the basis of a schematic illustration.

DETAILED DESCRIPTION OF AN EXEMPLARY EMBODIMENT

(3) A portion of the hydraulics of a dialysis machine is illustrated in FIG. 1 in a schematic manner, as an example for a fluid management system.

(4) The flushing medium source 14 initially supplies a flushing solution into the water input chamber 10. To fill the hydraulics, the flushing solution is guided into the first fluid portion 15 through the degassing pump 1 and the degassing chamber 9 into the fresh water chamber of the left balance chamber 8, and through the locking device 4 into the second fluid portion 16 by operating the flow pump 2. There, the flushing solution is guided back into the water input chamber 10 with a ventilation means 17 via the waste water side of the right balance chamber 8. A pressure measuring means 5 is arranged in the first fluid portion 15 upstream of the locking device 4. Pressure measuring means 6 is arranged in the second fluid portion 16 downstream from the locking device 4. In addition, a coupling point 7 for an extracorporeal blood tube system is located in the second fluid portion 16.

(5) This coupling point 7 is arranged on the machine front. After coupling to the extracorporeal blood tube system, a direct delivery of dialysate from the hydraulics into the extracorporeal blood circuit can thus take place. To provide for a complete disinfection of this coupling point, the latter has, e.g., a coaxial design comprising an inner tube and an outer tube arranged coaxially around it. The inner tube is recessed with respect to the outer tube. In the flushing or disinfecting mode, the outer tube is sealed against the outside by means of a flap. In the flushing or disinfecting mode, the flushing or disinfecting solution, respectively, flows through the inner tube into the outer tube arranged coaxially around it, and from there into an outlet line. The distance between inner and outer tube is 6 mm. The coupling point 7 is furthermore inclined along its longitudinal axis in such a way that the liquid outlet is arranged lower than the output of the inner tube, in order to facilitate a complete emptying of the port of liquid. Air bubbles can thus get stuck upstream of the recessed inner tube and cannot readily be transported away into the outlet in the flushing mode in response to a laminar flow through this narrow gap of the outer tube against the buoyancy force. In particular this bottleneck, which forms the connection point to the tube system and thus to a possibly infectious medium, would then not be completely accessible for a disinfecting solution. The air-free filling furthermore optimizes the heat transfer through the liquid disinfectant until the sealing of the flap and the complete flush-out of the disinfecting solution after conclusion of the disinfection.

(6) To achieve a complete removal of air bubbles, the dialysis machine has a control unit 3. This control unit 3 is configured to fill the fluid portions 15 and 16 by operating the flow pump 2 with a continuous flow, and to circulate them subsequently.

(7) In response to simultaneous operation of the flow pump 2 and of the degassing pump 1, the locking device 4 is then closed. A positive pressure is built up in the first fluid portion 15, a negative pressure results in the second fluid portion 16. Air bubbles, which have not passed a constriction of the through lumen in the second fluid portion 16 during the flushing, initially expand in the negative pressure. As soon as the pressure measuring means 5 and 6 detect a sufficient pressure difference between first 15 and second fluid portion 16, the locking device 4 is opened, whereby a pressure compensation takes place. By means of the shock pressure in the second fluid portion 16, the air bubbles are divided into smaller gas bubbles. The latter are then conveyed immediately through the degassing pump through the constriction and then reach into the water input chamber 10, where they are discharged into the atmosphere. When the fluid level in the water input chamber falls below a predetermined value, it is filled with flushing solution.

(8) If a degassing is to be avoided during phases with high flow, the degassing throttle 9 can be bypassed by opening the valve 12.

(9) The process of alternately closing and opening the locking device 4 can be repeated several times, e.g. 7 times.

(10) The fluid conveying means 1 and 2 are subsequently stopped, the system is ventilated, and the valves are closed.

(11) A flow chart of an embodiment of the method according to the invention is illustrated in FIG. 2.

(12) At the beginning of the dialysis treatment, the outer tube of the coaxially constructed coupling point of the dialysis machine for the extracorporeal blood tube system and the fluid line leading away therefrom is emptied and is thus filled with air.

(13) In a first step 101 of the filling process, the water input chamber 10 illustrated in FIG. 1, and a compartment of the balance chambers are in each case filled with water.

(14) In a second method step 102, the flushing solution is circulated in the fluid circuit, which is shown in FIG. 1. The valves 4, 11, and 12 are open. This method step lasts approx. 5 seconds.

(15) In a third method step 103, the coupling point is flushed with a continuous flow. This method step 103 lasts approx. 5 seconds.

(16) In a fourth method step 104, the valve 4 is closed, and a positive pressure of above 1800 hPa is built up upstream of the valve by operating the degassing pump 1. A negative pressure of less than 400 hPa is built up downstream from the valve 4 by operating the flow pump 2. This method step lasts approx. 2 seconds.

(17) In a fifth method step 105, the pressure difference is reduced, in that valve 4 is opened for approx. 4 seconds.

(18) To completely remove the air, the method steps 104 and 105 are then repeated up to seven times.

(19) In a sixth method step 106, the pumps 1 and 2 are stopped, and the system is ventilated.

(20) In a seventh method step 107, the used valves are closed.

REFERENCE LIST

(21) First pump 1 Second pump 2 Control unit 3 Locking means 4 First pressure measuring means 5 Second pressure measuring means 6 Coupling point for extracorporeal blood tube system 7 Balance chambers 8 Degassing chamber 9 Water input chamber 10 Valve 11 Valve 12 Fluid management system 13 Flushing medium source 14 First fluid line portion 15 Second fluid line portion 16 Ventilation means 17