METHOD OF FLUSHING A DIALYZER

Abstract

The present invention relates to a method of flushing a dialyzer with a flushing liquid, wherein the dialyzer is arranged in a dialyzate-side circuit of a blood treatment device and wherein the dialyzer has at least one dialyzate-side chamber which has at least one inlet and at least one outlet for the flushing liquid and which is flowed through by the flushing liquid, wherein at least one property of the flushing liquid is measured at the outlet of the dialyzer or downstream of the dialyzer in the dialyzate-side circuit to obtain one or more outlet-side measured values, wherein the property depends on the quantity of the air in the flushing liquid.

Claims

1. A method of flushing a dialyzer with a flushing liquid, wherein the dialyzer is arranged in a dialyzate-side circuit of a blood treatment device and wherein the dialyzer has at least one dialyzate-side chamber which has at least one inlet and at least one outlet for the flushing liquid and which is flowed through by the flushing liquid, characterized in that at least one property of the flushing liquid is measured at the outlet of the dialyzer or downstream of the dialyzer in the dialyzate-side circuit to obtain one or more outlet-side measured values, wherein the measured property depends on the quantity of the air in the flushing liquid.

2. A method in accordance with claim 1, characterized in that the conductivity of the flushing liquid or the speed of sound at which sound propagates in the flushing liquid or an optical property of the flushing liquid is measured.

3. A method in accordance with claim 1, characterized in that at least one property of the flushing liquid is likewise measured at the inlet of the dialyzer or upstream of the dialyzer to obtain one or more inlet-side measured values, wherein the measured property depends on the quantity of the air in the flushing liquid and wherein the inlet-side measured value or values are compared with the outlet-side measured value or values.

4. A method in accordance with claim 1, characterized in that the flushing process is ended or a sufficient flushing is signaled or a conclusion thereon is drawn when the outlet-side measured values are constant or lie in a certain tolerance range.

5. A method in accordance with claim 1, characterized in that the flushing process is ended or a sufficient flushing is signaled or a conclusion thereon is drawn when the standard deviation of the outlet-side measured values is below a certain limit value or does not exceed a certain limit value or lies within a certain tolerance range.

6. A method in accordance with claim 1, characterized in that the flushing process is ended or that a sufficient flushing or is signaled or a conclusion thereon is drawn when the expected value of the outlet-side measured values lies within a certain tolerance range and/or when the difference of the expected values of the outlet-side measured values and of the inlet-side measured values is below a specific limit value or does not exceed a certain limit value.

7. A method in accordance with claim 1, characterized in that the quotient is determined from the difference of the measured property and of this property with a completely ventilated dialyzate-side chamber and the difference from the property with a completely vented and a completely ventilated chamber and the flushing process is ended or a sufficient flushing is signaled or a conclusion thereon is drawn on the basis of the value of this quotient.

8. A method in accordance with claim 1, characterized in that the volume rate at which the flushing liquid flows through the dialyzate-side chamber is constant in time or variable in time.

9. An apparatus for flushing a dialyzer with a flushing liquid, having a dialyzer and having a dialyzate-side circuit of a blood treatment device in which the dialyzer is arranged, wherein the dialyzer has at least one dialyzate-side chamber which has at least one inlet and at least one outlet for the flushing liquid and which can be flowed through by the flushing liquid, characterized in that at least one sensor is arranged at the outlet of the dialyzer or downstream of the dialyzer in the dialyzate-side circuit, the sensor being configured to measure at least one property of the flushing liquid to obtain one or more outlet-side measured values, with the measured property depending on the quantity of the air in the flushing liquid.

10. An apparatus in accordance with claim 9, characterized in that the sensor is configured such that it measures the conductivity of the flushing liquid or the speed of sound at which sound propagates in the flushing liquid or measures an optical property of the flushing liquid.

11. An apparatus in accordance with claim 9, characterized in that at least one further sensor is arranged at the inlet of the dialyzer or upstream of the dialyzer and is configured to measure at least one property of the flushing liquid to obtain one or more inlet-side measured values, with the property depending on the quantity of the air in the flushing liquid; and in that at least one evaluation unit is provided which is configured to compare the inlet-side measured value or values with the outlet-side measured value or values.

12. An apparatus in accordance with claim 9, characterized in that at least one evaluation unit is provided which is configured such that it ends the flushing process or signals a sufficient flushing when the outlet-side measured values are constant or lie in a certain tolerance range.

13. An apparatus in accordance with claim 9, characterized in that at least one evaluation unit is provided which is configured such that the flushing process is ended or a sufficient flushing is signaled when the standard deviation of the outlet-side measured values lies below a certain limit value or does not exceed a certain limit value or lies within a certain tolerance range.

14. An apparatus in accordance with claim 9, characterized in that at least one evaluation unit is provided which is configured such that the flushing process is ended or a sufficient flushing is signaled when the expected value of the outlet-side measured values lies within a certain tolerance range and/or when the difference of the expected values of the outlet-side and of the inlet-side measured values lies below a certain limit value or does not exceed a certain limit value.

15. An apparatus in accordance with claim 9, characterized in that at least one evaluation unit is provided which is configured such that the quotient is determined from the difference of the measured property and of this property with a completely ventilated dialyzate-side chamber and the difference from the property with a completely vented and completely ventilated chamber and such that the flushing process is ended or a sufficient flushing is signaled on the basis of the value of this quotient

16. An apparatus in accordance with claim 9, characterized in that at least one pump is provided which is configured such that it conveys the flushing liquid through the dialyzate-side chamber, with the pump being configured such that it conveys the flushing liquid through the dialyzate-side chamber at a conveying rate constant in time or variable in time.

17. A blood treatment device, in particular a dialysis machine, having at least one apparatus in accordance with claim 9.

Description

[0037] 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:

[0038] FIG. 1: a schematic view of a dialyzer having the dialyzate-side circuit as well as conductivity sensors in the dialyzate-side feed line and in the dialyzate-side drain line;

[0039] FIG. 2: the time development of the conductivity measured by means of the sensors in accordance with FIG. 1 during the flushing process; and

[0040] FIG. 3: the time development of the conductivities measured by the sensors in accordance with FIG. 1 during the flushing process with sufficient venting.

[0041] FIG. 1 shows a dialyzer 10 as well as a part of the hydraulic system or of the dialyzate-side circuit in the form of the feed line 12 and the drain line 14. In accordance with the arrow direction shown, flushing liquid is led into or led out of the dialyzate-side chamber through these lines. Dialysis solution is conducted to the dialyzer and from the dialyzer through these lines during the operation of a blood treatment device.

[0042] The two lines 12, 14 are in fluid communication with a dialyzate-side chamber of the dialyzer. It is separated from a blood-side chamber of the dialyzer by one or more membranes, preferably by a hollow fiber bundle. The blood-side inflows or outflows of the dialyzer which are connected to the blood-side chamber are marked by the reference numerals 16 and 18 in FIG. 1.

[0043] As can be seen from FIG. 1, a respective conductivity measuring cell 12′, 14′, which measure the conductivity of the flushing liquid before the dialyzer 10 and also after the dialyzer 10, are both located in the feed line 12 and in the drain line 14. In treatment operation, these conductivity sensors 12′, 14′ serve the measurement of the conductivity of the dialysis solution.

[0044] The conductivity of the air/liquid mixture during the flushing process of the dialyzer can be determined by means of the conductivity cells 12′, 14′ and a check can be made whether the air portion in the mixture is reduced, from which a conclusion can be drawn on a sufficient air removal from the dialyzate-side chamber of the dialyzer 10.

[0045] The measurement of the conductivity or of another property which depends on the presence of air in the dialysis solution or flushing liquid is determined either continuously in time or at a plurality of points in time.

[0046] FIG. 2 shows the conductivities of the flushing liquid flowing into the dialyzate-side chamber of the dialyzer 10 (CD IN) and of the flushing liquid flowing out of the dialyzate-side chamber of the dialyzer 10 (CD OUT) during the flushing process.

[0047] As can be seen from FIG. 2, the conductivity of the flushing liquid flowing into the dialyzer chamber shows a constant value of 14.6 mS/cm, while the conductivity of the air/liquid mixture flowing out of the dialyzer first has no conductivity and then has substantial fluctuations. The conductivity of the flushing liquid flowing out of the dialyzer only stabilizes after a certain flushing time since the quantity of the air which is taken along with the flushing liquid reduces over the course of the flushing process.

[0048] The status of the dialyzer filling or of the air removal can preferably be checked in connection with a variable volume rate for the efficient flushing of the dialyzer chamber with reference to the analysis of the conductivities or of another suitable parameter of the inflowing or outflowing flushing liquid.

[0049] As can be seen from FIG. 2, the conductivities at the inflow side and at the outflow side equalize toward the end of the flushing process.

[0050] FIG. 3 shows the curve of the conductivities as in FIG. 2 from a time onward at which the filling has been successfully ended or the air removal has taken place. As can be seen from FIG. 3, it results that the fluctuations are small at the outlet side and furthermore that the difference between the inlet-side measured values and the outlet-side measured values is likewise small.

[0051] The flushing process preferably takes place with a variable flushing volume conveying i.e. with a variable conveying rate of the flushing liquid for generating turbulences in the dialyzer. A constant conveying rate is, however, also covered by the invention.

[0052] Provision is made in a conceivable embodiment of the invention that the flushing procedure is ended or that it is correspondingly signaled that it can be ended when the outlet-side measured value in the outflowing air/liquid mixture or in the outflowing flushing liquid largely corresponds to the inlet-side measured value. On a successful filling procedure, no more air is transported out of the dialyzer so that the conductivity of the liquid flowing out of the dialyzer is stable. It can be understood by this that there is a small standard deviation over the statistical expected value. The standard deviation is suitable as a quality parameter for an evaluation of the successful venting. The standard deviation can be determined while taking account of an expected value X.sub.C.

[0053] It has proved to be meaningful to calculate the expected value X.sub.C and a standard deviation σ.sub.c within a window moving in time with N sampling elements or measured points both for the inflowing liquid and for the outflowing liquid:

[00001] $〈 X_{C} 〉 = \frac{1}{N} .Math. {.Math.}_{i = 1}^{N} .Math. c_{i}; σ_{C} = \frac{1}{N} .Math. \sqrt{{.Math.}_{i = 1}^{N} .Math. {.Math. 〈 X_{C} 〉 - c_{i} .Math.}^{2}}$

[0054] The expected values of the conductivity of the inflow and outflowing flushing liquid should coincide within a tolerance range, for example in the order of 0.1 mS/cm. The deviations σ.sub.C, which are a measure for the stability of the conductivity over time, should also lie within a narrow range (e.g. 0.05 mS/cm) in a comparison of the inflowing or outflowing liquid. I.e. the two standard deviations of the inlet-side measured values and of the outlet-side measured values should likewise coincide or their differences should lie within the named tolerance range.

[0055] The venting procedure can be aborted when a certain quality of the venting has been reached. This can be the case when both the expected values and the deviations of the conductivity of the inflowing or outflowing flushing liquid lie within a tolerance range defined by the quality.

[0056] These statements naturally do not only apply to the conductivity, but also to any desired other measurement parameter which represents a measure for the presence of air in the flushing liquid.

[0057] As initially stated, alternative methods for detection can also be used in addition to the detection of air segments in the conductive liquid by means of conductivity sensors. The measurement of the sound of speed, which is considerably different in air and in liquid, can be considered, for example. An ultrasound detector can thus also be used as the sensor which is used alternatively or additionally to the conductivity sensors.

[0058] It is conceivable that the sound transit time of sound pulses is analyzed, for example within a certain volume flowing through the sound sensor, and that the ratio of the determined mean transit time v less the sound transit time in completely ventilated paths v.sub.air is set to the transit time difference between completely ventilated and completely vented paths v.sub.liquid:

[00002] $Φ [%] = \frac{v - v_{Luft}}{v_{Fl .Math. \overline{u} .Math. ssig} - v_{Luft}} \times 100$

[0059] This ratio in percent is a measure for the degree of venting of the dialyzer. If the ratio is 100%, the determined mean transit time v corresponds to the transit time with a completely vented path v.sub.liquid, i.e. a conclusion can be drawn that a complete venting has taken place.

[0060] This procedure naturally also does not only relate to the speed of sound as a measurement value, but can also be used for any other measurement value.

[0061] Optical analyses of the degree of venting are also conceivable in addition to sound analyses. Since the dielectricities between aqueous solutions and air differ considerably for many optical frequencies, the degree of venting can also be determined by means of optical measurement methods and a decision can thereupon be made that the flushing process can be terminated or ended.

METHOD OF FLUSHING A DIALYZER

Assignee

Inventors

Cpc classification

Classification Explorer

A61M2205/3306

HUMAN NECESSITIES

Classification Explorer

A61M1/3626

HUMAN NECESSITIES

Classification Explorer

A61M2205/3375

HUMAN NECESSITIES

Classification Explorer

A61M1/3643

HUMAN NECESSITIES

Classification Explorer

A61M2205/3317

HUMAN NECESSITIES

Classification Explorer

A61M1/3644

HUMAN NECESSITIES

International classification

Classification Explorer

A61M1/36

HUMAN NECESSITIES

Abstract

Claims

Description