METHOD AND APPARATUS FOR CHECKING A DIALYZER FOR THE PRESENCE OF A LEAK

Abstract

The present invention relates to a method for checking a dialyzer for the presence of a leak in the semipermeable membrane of the dialyzer, wherein the membrane divides the inner dialyzer space into a least one blood chamber and into at least one dialyzate chamber, wherein the blood chamber is flowed through by blood in the operation of the dialyzer and is in fluid communication with a blood-side line system and the vascular system of the patient, and wherein the dialyzate chamber is flowed through by dialysis fluid in the operation of the dialyzer and is in fluid communication with a dialyzate-side line system, wherein the method comprises the following steps: a) emptying the blood chamber or the dialyzate chamber of blood and of dialysis fluid respectively and keeping the fluid (blood or dialyzate) in the non-emptied dialyzate chamber or blood chamber;

b) building up a test pressure by means of a gas, in particular by means of air, in the emptied blood chamber or in the emptied dialyzate chamber; and c) measuring the pressure drop over time in the emptied blood chamber or in the emptied dialyzate chamber or in the line system respectively in fluid communication therewith and/or measuring the pressure increase in the non-emptied blood chamber or in the non-emptied dialyzate chamber or in the line system respectively in fluid communication therewith or measuring the number of air bubbles or of a parameter correlated with the number of air bubbles in the non-emptied blood chamber or in the non-emptied dialyzate chamber or in a line system respectively in fluid communication therewith,
wherein the steps a) to c) are carried out subsequent to the blood treatment of the patient and subsequent to the disconnection of the patient from the blood-side line system.

Claims

1. A method for checking a dialyzer (D) for the presence of a leak in the semipermeable membrane (11) of the dialyzer (D), wherein the membrane (11) divides the inner dialyzer space into a least one blood chamber (12) and into at least one dialyzate chamber (10), wherein the blood chamber (12) is flowed through by blood in the operation of the dialyzer and is in fluid communication with a blood-side line system (BS) and the vascular system of the patient (P) and wherein the dialyzate chamber (10) is flowed through by dialysis fluid in the operation of the dialyzer and is in fluid communication with a dialyzate-side line system (DS), wherein the method comprises the following steps: a) emptying the blood chamber (12) or the dialyzate chamber (10) of blood and of dialysis fluid respectively and keeping the fluid (blood or dialyzate) in the non-emptied dialyzate chamber or blood chamber (10, 12); b) building up a test pressure by means of a gas, in particular by means of air, in the emptied blood chamber (12) or in the emptied dialyzate chamber (10); and c) measuring the pressure drop over time in the emptied blood chamber (12) or in the emptied dialyzate chamber (10) or in the line system (BS, DS) respectively in fluid communication therewith and/or measuring the pressure increase in the non-emptied blood chamber (12) or in the non-emptied dialyzate chamber (10) or in the line system (BS, DS) respectively in fluid communication therewith or measuring the number of air bubbles or of a parameter correlated with the number of air bubbles in the non-emptied blood chamber (12) or in the non-emptied dialyzate chamber (10) or in a line system (BS, DS) respectively in fluid communication therewith, wherein the steps a) to c) are carried out subsequent to the blood treatment of the patient (P) and subsequent to the disconnection of the patient (P) from the blood-side line system (BS).

2. A method in accordance with claim 1, characterized in that, subsequent to the check in accordance with steps a) to c), no disinfection of the dialyzate-side line system (DS) is carried out if no leak was detected in the membrane (11) of the dialyzer (D) on the check.

3. A method in accordance with claim 1, characterized in that the measurement of the pressure is carried out in the dialyzate chamber (10), in the dialyzate-side line system (DS), in the blood chamber (12) or in the blood-side line system (BS) or in a plurality of the aforesaid elements.

4. A method in accordance with claim 1, characterized in that at least one bubble detector (9) is arranged in the blood-side line system (BS) and/or in the dialyzate-side line system (DS) and is configured to measure air bubbles in the blood or in the dialysis fluid; and in that the check for a leak of the membrane (11) is carried out on the basis of the number of air bubbles or on the basis of a parameter correlated therewith.

5. A method in accordance with claim 1, characterized in that the number of air bubbles or of a parameter correlated therewith is determined with a running blood pump (4) or with a running dialysis fluid pump.

6. A method in accordance with claim 1, characterized in that step c) is carried out while the non-emptied chamber (10, 12) or the non-emptied line system (BS, DS) is closed.

7. A method in accordance with claim 1, characterized in that the build-up of the test pressure is carried out multiple times and a continuation is only made with step c) when the drop of the test pressure over time does not exceed a limit value.

8. A method in accordance with claim 1, characterized in that the build-up of the test pressure in step b) is carried out by means of a compressor which conveys environmental air into the emptied blood chamber (12) or dialyzate chamber (10) or in the line system (LS, DS) in communication therewith.

9. A method in accordance with claim 1, characterized in that the pressure development or the number of detected bubbles or the parameter correlated therewith is displayed and/or that an evaluation is made on the basis of one or more of these measured values as to whether the membrane (11) has a leak and the result of the evaluation is displayed.

10. An apparatus for checking a dialyzer (D) for the presence of a leak in the membrane (11) of the dialyzer (D) comprising the dialyzer (D) which is divided by the at least one semipermeable membrane (11) into at least one blood chamber (12) and into at least one dialyzate chamber (10), comprising at least one blood-side line system (BS) which is in fluid communication with the blood chamber (12) and which is in fluid communication with the blood chamber (12) and with the vascular system of a patient (P) during the treatment, and comprising at least one dialyzate-side line system (DS) in fluid communication with the dialyzate chamber (10), wherein the blood flows through the blood-side line system (BS) and the blood chamber (12) and the dialysis fluid flows through the dialyzate chamber (10) and the dialysis fluid system (DS) during the blood treatment, characterized in that the apparatus has a control unit and means which are controlled by this unit and are configured to carry out the method steps in accordance with claim 1.

11. An apparatus in accordance with claim 10, characterized in that the apparatus has one or more pressure sensors which are arranged indirectly or directly at the dialyzate chamber (10), at the dialyzate-side line system (DS), at the blood chamber (12) or at the blood-side line system (BS) or in a plurality of the aforesaid elements; and in that the apparatus is configured to detect the pressure development over time and preferably to draw a conclusion on the presence of a leak in the membrane (11) of the dialyzer (D) on the basis thereof.

12. An apparatus in accordance with claim 10, characterized in that the apparatus has at least one bubble detector (9) in the blood-side line system (BS) and/or in the dialyzate-side line system (DS) which is configured to measure air bubbles in the fluid (blood or dialysis fluid); and in that the apparatus preferably has means which are configured such that they carry out the check of the leak-tightness of the membrane (11) of the dialyzer (D) on the basis of the number of air bubbles or of a parameter correlated therewith.

13. An apparatus in accordance with claim 10, characterized in that the apparatus has means for emptying the blood from the blood chamber (12) and/or for emptying the dialysis fluid from the dialyzate chamber (10); and in that the apparatus comprises means, in particular at least one compressor, for the introduction of pressurized air into the blood chamber (12) emptied of blood or into the dialyzate chamber (10) emptied of dialysis fluid and optionally the line system (LS, DS) in fluid communication therewith.

14. An apparatus in accordance with claim 10, characterized in that the apparatus has display means which are configured to display the pressure development or the number of detected bubbles or the parameter correlated therewith; and/or in that the apparatus has an evaluation unit which is configured such that it carries out an evaluation on the basis of one or more of said measured values as to whether the membrane (11) has a leak and displays the result of the evaluation.

15. A dialysis device, characterized in that the dialysis device has at least one apparatus in accordance with claim 10.

Description

[0034] Further details and advantages of the invention will be explained in more detail with reference to an embodiment shown in the drawing. There are shown:

[0035] FIG. 1: a schematic view of the dialyzate side and of the blood side of a dialysis device; and

[0036] FIG. 2: pressure developments over time for an intact dialyzer membrane and for a defective dialyzer membrane;

[0037] Reference symbol D indicates the dialyzer which is divided by a semipermeable membrane 11, which is preferably formed by a bundle of hollow fibers, into a dialyzate chamber 10 and into a blood chamber 12.

[0038] The blood-side line system BS, which forms the extracorporeal blood circuit, is in communication with the blood chamber 12. The blood pump 40 is located upstream of the dialyzer D and the clamp K2 is located upstream of the blood pump 40 in the blood-side line system BS. The venous drip chamber 30 is located downstream of the dialyzer D. The venous clamp K1 is arranged downstream thereof.

[0039] The terms upstream and downstream relate to the direction of flow of the blood with a blood pump 40 in operation, said direction of flow being marked by an arrow in the Figure.

[0040] Not only the hose line which represents a component of the blood-side line system BS opens into the drip chamber 30, but also a further line 22. The compressor which conveys air out of the environment into the blood-side line system BS for carrying out the method is located in this further line 22. The valve V3 is located between the compressor 20 and the drip chamber 30. The reference symbol PV indicates a pressure sensor which is located in the venous part of the blood-side line system.

[0041] Reference numerals 1 and 2 indicate the arterial and venous connectors of the extracorporeal circuit and the latter is or can be connected by them to the vascular system of the patient P.

[0042] In the operation of the blood pump 40, blood is conveyed, with a connected patient, through the line 41 to the dialyzer D and from the dialyzer D through the line 42 and the drip chamber 30 back to the patient.

[0043] The dialyzate-side line system DS is located on the dialyzate side and has lines, in particular hose lines, by means of which dialysis fluid is guided into or out of the dialyzate chamber 10 in the operation of the device. The movement of the dialysis fluid in the dialyzate-side line system DS is carried out by a pump, not shown.

[0044] The terms upstream and downstream relate to the direction of flow of the dialysis fluid with a pump for the dialysis fluid in operation, said direction of flow being marked by an arrow in the Figure. Fresh dialysis fluid is conveyed to the dialyzer D through the line 51. Consumed dialysis fluid is extracted from the dialyzer D through the line 52.

[0045] A respective pressure sensor P1 and P2 is located upstream and downstream of the dialyzer in the dialyzate-side line system DS, as can be seen from FIG. 1.

[0046] Reference symbol B schematically indicate the balancing system which serves the balancing of the dialysis fluid supplied to and removed from the dialyzer D and which communicates with the supplying and removing lines 51 and 52. The lines 51 and 52 or the balancing system can be blocked by valves V4, V5.

[0047] The line 53 branches off from the line 52 leading away from the dialyzer D and leads to the outflow A for consumed dialysis fluid.

[0048] As can be seen from FIG. 1, the valve V2, by means of which the line 52 can be closed, is located between the dialyzer D and the branching of the line 53 in the line 52. A further valve V1 is arranged in the line 53. The line 53 can be blocked by means of the valve V1.

[0049] Instead of the above-named clamps K1, K2, valves or also any other desired blocking means can also be used. The position of the clamps is also exemplary, i.e. the clamps can also be arranged at another place or in a different number.

[0050] Instead of the above-named valves V1, V2, V3, V4, V5, clamps or also any other desired blocking means can also be used. The position of the valves is also exemplary, i.e. the clamps can also be arranged at another place or in a different number.

[0051] Two test sequences are described by way of example in the following by means of which it can be determined whether the membrane 11 has one or more leaks or is intact.

[0052] In a first embodiment, the blood side is first emptied of blood.

[0053] The clamps K1 and K2 are closed. The blood pump 40 is switched off. The balancing chamber system B is blocked by closing the valves V4, V5. This applies to the total test procedure in this embodiment.

[0054] The compressor 20 is switched on, the valve V3 is opened and the valves V1 and V2 are opened.

[0055] The blood located on the blood side is displaced by the air over the membrane 11 to the dialyzate side. It moves from there, with open valves V1, V2, through the lines 52 and 53 into the drain A.

[0056] The compressor remains in operation for so long until a pressure increase is determined by means of the pressure sensor PV.

[0057] The compressor 20 is then switched off and the valve V1 is closed.

[0058] The build-up of the test pressure on the blood side emptied from blood starts subsequent to this. The blood pump 40 remains switched off for this purpose and the balancing chamber system B is blocked. The compressor 20 is switched on while the valve V1 is closed and the valve V2 remains open. The compressor 20 remains switched on for so long until a specific pressure, e.g. 1250 mm Hg, is reached at the pressure sensor PV at the blood side.

[0059] The compressor is then switched off, the valve V3 is closed and the valve V1 is opened. A check is then made whether the pressure drop per time on the blood side now vented or filled with pressurized air exceeds a limit value. If this is the case, the procedure is repeated, i.e. the compressor 20 is switched on and the valve V3 is opened again. The valve V1 is closed and the valve V2 is opened. The compressor is then switched off, the valve V3 is closed and the valve V1 is opened. The pressure development over time is subsequently determined at the pressure sensor PV.

[0060] This process is repeated until the pressure drop per time on the blood side does not exceed a limit value.

[0061] If this is the case, the actual pressure holding test begins. For this purpose, the compressor 20 is switched off, the valve V3 is closed and the valve V1 is closed. The balancing chamber system B remains blocked. The pressure holding test is thus carried out when the dialyzate side filled with dialysis fluid is closed, i.e. when the supply and removal lines of the dialyzate side are blocked. This allows an air intake into the dialyzate side to be measured precisely by a pressure increase on the dialyzate side.

[0062] After switching off the compressor 20 and after the closing of the valve V1, the pressure development on the dialyzate side is determined by means of the pressure sensor(s) P1 and/or P2. The filter D is qualified as in order if the pressure increase over time measured by the sensor(s) P1 and P2 does not exceed a limit value, i.e. if the pressure increase measured at the dialyzate side is comparatively small.

[0063] If this is not the case, however, i.e. if the pressure at the sensors P1 and/or P2 increases comparatively fast, this is due to a leak of the filter membrane 11. A conclusion can thus be drawn from the speed of the pressure increase measured at the dialyzate side on whether the membrane of the dialyzer D is in order or has one or more leaks.

[0064] If the pressure increase measured by means of the sensors P1 and P2 is not identical, this indicates an air intake into the hydraulics so that a hydrostatic pressure difference due to air intake results in this deviation.

[0065] Alternatively or additionally to the measurement of the pressure increase on the dialyzate side, the measurement of the pressure drop on the blood side is also conceivable during the pressure holding test.

[0066] FIG. 2 shows the result of the pressure development over time for an intact membrane and FIG. 3 for a defective filter in which the membrane has one or more leaks.

[0067] The above-described build-up of the test pressure on the blood side by a repeated opening and closing of the valve V1 takes place in the time period A and is indicated by the curve K1. The respective higher value shows the closed valve V1, the respective lower value shows the opened valve V1.

[0068] The curve K2 shows the pressure development measured at the pressure sensor PV. As can be seen from FIG. 2, the pressure build-up with air on the emptied blood side is repeated so often until the pressure loss with opened valves V1 and V2 does not exceed a specific limit value per time unit.

[0069] The pressure holding test only starts with the beginning of section B when this requirement is satisfied. This is carried out while the dialyzate side is closed with respect to the drain A and overall so dialysis fluid can neither be supplied nor removed.

[0070] The curves K3 and K4 show the pressure developments over time measured at the sensors P1 and P2. It results from FIG. 2 that the pressure increase in the range of approximately 50 mm Hg in approximately 5 min. from the start of section B. This is an acceptable value in the embodiment described here so that a conclusion can be drawn from this of an intact, i.e. leak-free membrane.

[0071] In contrast, with the measurement result in accordance with FIG. 3, the pressure increase measured at the sensors P1 and P2 is in a range of approximately 200 mm Hg in approximately 5 min. from the start of section B, which is above a limit value. A conclusion of a defective membrane is made in this case.

[0072] The named values are naturally only examples which do not restrict the invention.

[0073] The second embodiment starts with the disconnection of the patient by closing the clamps K1 and K2 and by stopping the blood pump 40. The compressor 20 is switched off and the valve V3 is closed so that the blood side is closed overall.

[0074] The emptying of the dialyzate side by means of a standard emptying program then follows through the line 52 with opened valves V1 and V2 to the drain A. A venting valve or the compressor can be provided in the line 51 for the emptying. The dialyzate coupling is open on the running of the emptying program.

[0075] The valve V2 is subsequently closed and a test pressure is built up by means of air or of another gas on the dialyzate side emptied of dialysis fluid. This pressure build-up takes place by means of a compressor until the desired test pressure, e.g. 1250 mm Hg, is reached. The compressor is stopped.

[0076] As soon as this is the case, the valve V2 is closed and the connectors 1 and 2 are connected to one another so that a closed blood circuit is formed. The blood pump 40 is taken into operation.

[0077] The air bubble detector 9, which is arranged downstream of the drip chamber 30, for example, detects the number of air bubbles per time unit with a running blood pump 40. The membrane 11 is qualified as intact when the counted number of air bubbles per time unit does not reach a limit value; otherwise a conclusion is drawn on a defective membrane.

[0078] Alternatively or, additionally, the pressure is measured at the dialyzate-side pressure sensors P1 and P2. It is conceivable that the result of this pressure measurement and also the measured value of the air bubble detector is used for determining the integrity of the membrane 11.

[0079] It is thus possible, for example, that a conclusion is only made on an intact membrane when the number of air bubbles per time unit remains beneath a limit value and, in addition, the pressure loss on the dialyzate side does not exceed a limit value.

[0080] Microleaks in a dialyzer can be recognized by means of the present invention. The process takes place after the disconnection of the patient and after the carrying out of the blood treatment. Cross-contaminations can also be avoided by the process without any subsequent disinfection of the dialyzate side.