APPARATUS AND METHOD FOR PREPARING A DIALYSIS SOLUTION

Abstract

The present invention relates to an apparatus for preparing a dialysis solution, wherein the apparatus has a dialyzate line for conducting a dialysis solution and has means that are configured to discontinuously convey a dialysis solution in the dialyzate line, wherein the apparatus has a conductivity sensor that is arranged to measure the conductivity of the dialysis solution, and wherein the apparatus has a concentrate line opening into the dialyzate line upstream of the conductivity sensor at an addition point and having a concentrate pump and has a concentrate container from which the concentrate pump conveys concentrate into the concentrate line and from this into the dialyzate line, characterized in that the apparatus has a controller that is connected to the conductivity sensor and to the concentrate pump and that is configured to control the concentrate pump such that the conductivity fluctuations over time in the dialysis solution downstream of the addition point are reduced with respect to a continuous concentrate conveying.

Claims

1. An apparatus for preparing a dialysis solution, wherein the apparatus has a dialyzate line (10) for conducting a dialysis solution and has means that are configured to discontinuously convey a dialysis solution in the dialyzate line (10), wherein the apparatus has a conductivity sensor (20) that is arranged to measure the conductivity of the dialysis solution, and wherein the apparatus has a concentrate line (16) opening into the dialyzate line (10) upstream of the conductivity sensor (20) at an addition point (12) and having a concentrate pump and has a concentrate container (18) from which the concentrate pump (14) conveys concentrate into the concentrate line (16) and from this into the dialyzate line (10), characterized in that the apparatus has a controller (30) that is connected to the conductivity sensor (20) and to the concentrate pump (14) and that is configured to control the concentrate pump (14) such that the conductivity fluctuations over time in the dialysis solution downstream of the addition point (12) are reduced with respect to a continuous concentrate conveying.

2. An apparatus in accordance with claim 1, characterized in that the controller (30) is configured to control the concentrate pump (14) such that the conductivity of the dialysis solution over time is constant or fluctuates in a range from ±1-5% about the mean time value of the conductivity.

3. An apparatus in accordance with claim 1 or claim 2, characterized in that the apparatus has means for a spectral analysis of the basic pattern of the conductivity modulation with a constant concentrate supply into the dialysis solution, said means being configured to determine the harmonics of the conductivity modulation by spectral analysis; and in that the controller (30) is configured to successively control the concentrate pump (14) for frequencies of the harmonics such that the conductivity is modulated in phase and amplitude such that the harmonic contribution is eliminated from the conductivity spectrum.

4. An apparatus in accordance with claim 3, characterized in that the controller (30) is configured to start at the frequency of the harmonics with the greatest amplitude.

5. An apparatus in accordance with claim 3, characterized in that the controller (30) is configured such that it arbitrarily selects the order of the frequencies.

6. An apparatus in accordance with claim 1 or claim 2, characterized in that the controller (30) is configured to control the concentrate pump (14) in accordance with a trial and error principle to minimize conductivity fluctuations of the dialysis solution downstream of the addition point (12).

7. A dialysis machine having an apparatus in accordance with claim 1.

8. A dialysis machine in accordance with claim 7, characterized in that the means are configured to discontinuously convey a dialysis solution in the dialyzate line (10) by which the balancing chambers of the dialysis machine are formed.

9. A method of preparing a dialysis solution that flows discontinuously through a dialyzate line (10), wherein a concentrate is supplied to the dialysis solution, and wherein the conductivity of the dialysis solution is measured downstream of the addition point (12) for the concentrate, characterized in that the supply of concentrate is controlled such that the conductivity fluctuations over time in the dialysis solution are reduced with respect to a continuous concentrate conveying.

10. A method in accordance with claim 9, characterized in that the supply of concentrate is controlled such that the conductivity of the dialysis solution over time is constant or fluctuates in a range from ±1-5% about the mean time value of the conductivity.

11. A method in accordance with claim 9 or claim 10, characterized in that in a first step with a continuous concentrate supply, the basic pattern of the conductivity modulation is identified and the harmonics of the conductivity modulation are determined by spectral analysis and in a second step, the conductivity is successively modulated in phase and amplitude for frequencies of the harmonics by changing the concentrate supply such that the harmonic contribution is eliminated from the conductivity spectrum.

12. A method in accordance with claim 11, characterized in that step 2 is started at the frequency of the harmonics having the greatest amplitude; or in that the order of the selection of the harmonics is arbitrarily selected.

13. A method in accordance with claim 10, characterized in that the concentrate pump (14) is controlled in accordance with a trial and error principle to eliminate or reduce the conductivity fluctuations over time of the dialysis solution.

Description

[0034] There are shown:

[0035] FIG. 1: a regulated, profiled concentrate injection and a stable conductivity, i.e. a conductivity constant over time, that results at the dialyzer,

[0036] FIG. 2: a scheme for regulating or controlling the concentrate injection or concentrate supply into a discontinuous permeate flow; and

[0037] FIG. 3: a non-regulated concentrate injection and an unstable, i.e. time-variable, conductivity at the dialyzer.

[0038] FIG. 1 shows the desired state of a time-stable, i.e. constant, conductivity of the dialysis solution supplied to the dialyzer.

[0039] The progression shown at the bottom in FIG. 1 shows the progression of the concentrate injection over time, with the progression being set such that a constant conductivity results in the dialysis solution that is supplied to the dialyzer despite the discontinuous flow of the dialysis solution, i.e. a flow not constant over time.

[0040] To achieve this goal, concentrate from the reservoir 18 is added through the concentrate line 16 by means of the pump 14 into the line 10 leading to the dialyzer (cf. FIG. 2) at the addition point 12 in the direction of flow of the dialysis solution flowing through the line. The measurement of the conductivity takes place by means of the conductivity sensor 20 downstream of this addition point 12.

[0041] The signals of said conductivity sensor are supplied to the controller. In a first step with a continuous concentrate injection, the basic pattern of the conductivity modulation is determined and the elementary harmonics of this modulation are determined by spectral analysis.

[0042] For example, starting with the frequency of the harmonic having the greatest amplitude, the conductivity is modulated in amplitude and phase by modulation of the concentrate supply in step 2 until the associated harmonic contribution has disappeared from the conductivity spectrum.

[0043] The frequencies of the next harmonics having the greatest amplitudes with which the concentrate injection is modulated are successively sought so that the contributions in the spectrum of the data determined from the conductivity have disappeared.

[0044] These processes take place in the controller 30 that carries out a corresponding signaling or control of the concentrate pump 14 in dependence on the conductivity values.

[0045] It must generally be pointed out that the invention is not restricted to the addition of exactly one concentrate. The injection of a plurality of concentrates is rather also covered by the invention even though only the addition of one concentrate is shown in FIG. 3.

[0046] Its addition is modulated in accordance with the invention such that a time-constant or substantially time-constant conductivity and thus a constant concentrate concentration that does not fluctuate over time results in the dialysis solution supplied to the dialyzer.