Method and apparatus for preparing a medical solution

Abstract

The present invention relates to a method for preparing a medical solution from at least one first liquid component and at least one second liquid component, wherein the first component and the second component are conveyed with a respective conveying means to obtain a mixed solution, wherein the conveying means are operated such that a modulation of the concentration of the first and second components takes place and the conductivity or a parameter of the mixed solution correlating with the conductivity is measured at a measurement point, wherein the modulation of the concentrations takes place in a desired state such that no modulation or a specific desired modulation of the measured conductivity or of the parameter correlated with the conductivity occurs. The present invention furthermore relates to an apparatus for preparing a medical solution as well as to a blood treatment device having such an apparatus.

Claims

1. A method for preparing a medical solution from a first component and a second component, wherein the method comprises the steps of conveying the first component and the second component as liquids to obtain a mixed solution, characterized in that a modulation of concentrations of the first and second components in the mixed solution takes place, and measuring conductivity of the mixed solution or a parameter of the mixed solution correlating with the conductivity of the mixed solution at a measurement point, wherein the modulation of the concentrations of the first and second components takes place in a desired state such that a specific desired modulation or no modulation of the measured conductivity or of the parameter of the mixed solution correlated with the conductivity occurs, characterized in that the modulation of the concentrations of the first and second components takes place in a continuous sinusoidal form.

2. A method in accordance with claim 1, characterized in that the medical solution is a dialysis solution; and/or in that the first component is a base concentrate and the second component is an acid concentrate.

3. A method in accordance with claim 1, characterized in that no serial conveying of the first and second components past the measurement point takes place.

4. A method in accordance with claim 1, characterized in that a determination is made from an amplitude of the modulation of the measured conductivity or of the parameter of the mixed solution correlated with the conductivity of the mixed solution, and/or from a mean measured conductivity of the mixed solution or from a mean value of the parameter of the mixed solution correlated with the conductivity, and/or from a phase shift of the modulation of the measured conductivity of the mixed solution or of the parameter of the mixed solution correlated with the conductivity with respect to stimulation of the conveying as to which component differs in its concentration from an expected concentration.

5. A method in accordance with claim 1, characterized in that an evaluation of the measured conductivity or of the measured parameter of the mixed solution correlated with the conductivity is carried out and a conclusion is drawn on an error state on an occurrence of a difference from the no modulation or on a difference from the desired modulation.

6. A method in accordance with claim 5, characterized in that the conclusion is drawn from the error state on whether the component whose concentration differs from an expected concentration is the first component or the second component.

7. An apparatus for preparing a medical solution, wherein the apparatus has: a first conveying means for conveying a first component, a second conveying means for conveying a second component, and a main line in communication with the first and second conveying means such that the first and second components are conveyed into the main line by the first and second conveying means so that a mixed solution is created in the main line, characterized in that a sensor is provided in the main line for measuring conductivity or a parameter of the mixed solution correlated with the conductivity, in that the first and second conveying means are configured to effect in a continuous sinusoidal form a modulation of concentrations of the first and second components in the mixed solution in a desired state such that no modulation or a specific desired modulation of the measured conductivity or of the measured parameter of the mixed solution correlated with the conductivity occurs.

8. An apparatus in accordance with claim 7, characterized in that exactly one sensor is provided for measuring the conductivity or the parameter of the mixed solution correlated with the conductivity.

9. An apparatus in accordance with claim 7, characterized in that no sensor is provided for measuring the conductivity or a parameter of the first or second components correlated with the conductivity.

10. A blood treatment device having an apparatus in accordance with claim 7.

11. An apparatus in accordance with claim 7, characterized in that the apparatus has an evaluation unit to which a measurement by the sensor is supplied, wherein the evaluation unit is configured to conclude an error state when a modulation differing from the no modulation is found or when a modulation of the measured conductivity or of the parameter of the mixed solution correlated with the conductivity differing from the specific desired modulation is found.

12. An apparatus in accordance with claim 11, characterized in that the evaluation unit is configured such that it can be determined from the error state which component differs in its concentration in the mixed solution from an expected concentration.

13. An apparatus in accordance with claim 11, characterized in that the evaluation unit is configured such that a determination is made from an amplitude of the modulation of the measured conductivity of the mixed solution or of the parameter of the mixed solution correlated with the conductivity, and/or from a mean measured conductivity of the mixed solution or from a mean value of the parameter of the mixed solution correlated with the conductivity, and/or from a phase shift of the modulation of the measured conductivity of the mixed solution or of the parameter of the mixed solution correlated with the conductivity with respect to stimulation of the first and second conveying means as to which component differs in its concentration from an expected concentration.

Description

(1) 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:

(2) FIG. 1: the sum conductivity of the components A and B and the contribution of the individual conductivities of the components A and B to the sum conductivity;

(3) FIG. 2: the sum conductivity of the components A and B and the contribution of the individual conductivities of the components A and B to the sum conductivity for four different states A to C; and

(4) FIG. 3: a schematic view of a multi-component system comprising the components 1 to N with a conductivity measurement cell for measuring the sum conductivity of the mixed solution.

(5) The schematic time development of the sum conductivity 100, i.e. of the conductivity of the mixed solution composed of components A and B can be seen over time from FIG. 1. Furthermore, the time developments of the conductivities of components A and B (LF [=conductivity] component A, LF component B) are shown such that the value for the conductivity of component B (shown in dashed lines) is added to the value of the conductivity of component A so that a sum conductivity 100 constant in time results.

(6) The embodiment relates to the measurement of the conductivity and is also conceivable for the measurement of every other parameter. The invention thus also comprises the measurement of every other parameter of the mixed solution which correlates with the conductivity or with the concentration so that a conclusion can be drawn on the concentration of the components A and/or B or on their ingredients.

(7) It can be seen from FIG. 1 that the pump conveying of the components A and B is modulated such that the sum conductivity 100 of the mixture has no modulation, i.e. is constant in time. The sum concentration, which is correlated with the sum conductivity, is thus constant in time, whereas the concentrations of the components A and B in the mixed solution of both components vary in time.

(8) The conveying of the partial components A and B takes place in the embodiment shown in FIG. 1 phase-shifted by and modulated at a constant phase so that the sum concentration is constant or the sum conductivity has not fluctuations over time.

(9) The amplitude of the concentration fluctuations or conductivity fluctuations, which is shown in FIG. 1, is identical for both components A and B.

(10) If it is assumed that the partial components, i.e. the components A and B, which form the mixed solution or which are optionally present therein in a solvent such as in particular water, have the concentrations C.sub.A and C.sub.B and the individual conductivities or conductivity contributions of the components A and B in the mixed solution are LF.sub.A(t) and LF.sub.B(Tt):
LF.sub.A(t)=C.sub.A(1+f.sub.A sin(t))(1)
LF.sub.B(t)=C.sub.B(1+f.sub.B sin(t))(2)

(11) results for the time development of the conductivities with the relative amplitudes f.sub.A and f.sub.B and with a modulation:

(12) The relative amplitude is the quotient from the absolute amplitude of the concentrate fluctuation and the mean value of the concentration of the components A and B respectively in the mixed solution.
C.sub.Af.sub.A=C.sub.Bf.sub.B(3)

(13) results from the preferably aimed for freedom of modulations of the sum concentration or of the sum conductivity over time;

(14) and, resolved according to f.sub.A:
f.sub.A=f.sub.B(C.sub.B/C.sub.A)(4)

(15) If the relative amplitude of the modulation of component B is fixed e.g. to the value 0.5,
f.sub.A=0.5(C.sub.B/C.sub.A)=0.5 f.sub.AB(5)

(16) furthermore results

(17) where f.sub.AB=C.sub.B/C.sub.A.

(18) The relative amplitude f.sub.A of component A thus results directly from the aimed for ratio of the concentrations of components B and A in the mixed solution and from the relative amplitude f.sub.B of component B.

(19) The measured sum conductivity, i.e. the conductivity of the mixed solution composed of the individual components A and B, will have the desired expected physiological value in the desired state or will correlate with the expected sum concentration, i.e. with the sum of the concentrations of the individual components A and B. It then
LF.sub.A(t)+LF.sub.B(t)=C.sub.A(10.5(C.sub.B/C.sub.A)sin(t))+C.sub.B(1+0.5 sin(t))=C.sub.A+C.sub.B(6)

(20) results for the above-named example with f.sub.B=0.5 from the equations (1), (2) and (5).

(21) The expected values C.sub.A and C.sub.B in the mixed solution are constant in time so that a time consistency also results with respect to the sum conductivity LF.sub.A(t)+LF.sub.B(t).

(22) If the contribution of a component A or B differs from the respective added value, a modulation of the sum conductivity occurs. Depending on which component differs in concentration from the expected value, a specific modulation of the sum conductivity is generated, i.e. the measurement of the sum conductivity generates a characteristic fingerprint. It can thus be determined with reference to the measurement of the sum conductivity which component differs from the expected value.

(23) If it is assumed that component B does not correspond in its concentration in the mixed solution to the expected value C.sub.B, but only has the value C.sub.B, which represents a specific fraction 1/ of the expected value C.sub.B,
C.sub.B=1/C.sub.B(7)

(24) results.

(25) The sum conductivity in this case thus does not have the value resulting from equation (6), but it rather results while taking account of equations (5) and (7) as:

(26) $\begin{array}{cc}{\mathrm{LF}}_A\left(t\right)+{\mathrm{LF}}_B\left(t\right)=C_A\left(1-0.5\left(C_B/C_A\right)\sin \left(t\right)\right)+& \left(8\right)\\ C_B^{}\left(1+0.5\sin \left(t\right)\right)& \\ =C_A+1/C_B+\left(1/-1\right)C_B/2\sin \left(t\right)& \left(9\right)\end{array}$

(27) If thus the component contribution of component B differs by the factor 1/ from the expected value, the conductivity of the sum concentration, i.e. of the mixed solution of the two components A and B, in this embodiment thus modulates with the amplitude (1/1) C.sub.B/2.

(28) The mean sum conductivity in this case corresponds or correlates with C.sub.A+1/C.sub.B.

(29) If it is assumed that component A does not correspond in its concentration to the expected value C.sub.A, but only has the value C.sub.A, which represents a specific fraction 1/ of the expected value C.sub.A,
C.sub.A=1/C.sub.A(10)

(30) results.

(31) The sum conductivity in this case thus does not have the value resulting from equation (6), but it rather results while taking account of equations (5) and (10) as:

(32) $\begin{array}{cc}{\mathrm{LF}}_A\left(t\right)+{\mathrm{LF}}_B\left(t\right)=1/C_A\left(1-0.5\left(C_B/C_A\right)\sin \left(t\right)\right)+& \left(11\right)\\ C_B\left(1+0.5\sin \left(t\right)\right)& \\ =1/C_A+C_B+\left(1-1/\right)C_B/2\sin \left(t\right)& \left(12\right)\end{array}$

(33) If thus the component contribution of component A differs by the factor 1/ from the expected value, the conductivity of the sum concentration, i.e. of the mixed solution of the two components A and B, in this embodiment thus modulates with the amplitude (11/) C.sub.B/2.

(34) The mean sum conductivity in this case corresponds or correlates with 1/ C.sub.A+C.sub.B.

(35) The mean conductivity, its amplitude and the phase with respect to the actuator stimulation of the component conveying identify the component whose concentration differs from the expected value.

(36) If the components make different contributions to the sum concentration, a self-compensating difference can also be identified among the components.

(37) FIG. 2 shows the case in state A that the expected values of the contributions A and B have been reached. In this case, the sum conductivity 100 or the sum concentration of the mixed solution shows no modulation, i.e. is constant in time. The reference numerals 10 and 20 characterize the time development of the contributions of the conductivity or of the concentration of the partial components A (reference numeral 10) and B (reference numeral 20) to the conductivity 100 or concentration of the mixed solution.

(38) In the state B, the expected value 20 of component B has been reached, but the actual value of the concentration 10 of component A is below the expected value. The sum conductivity 100 or the sum concentration is below the expected value and is modulated with a phase shift with the different component A.

(39) In the state C, the expected value 10 of component A has been reached, but the actual value of the concentration 20 of component B is below the expected value. The sum conductivity 100 or the sum concentration is below the expected value and is modulated with a phase shift with the differing component B.

(40) In the state D, both expected values of components A and B have not been reached. However, the difference is compensatory, i.e. the sum contribution corresponds to the expected value, i.e. the mean value of the sum conductivity 100 or of the sum concentration corresponds to the expected value.

(41) However, in this case, the sum conductivity 100 or the sum concentration is also modulated, i.e. is not constant in time.

(42) A difference of the concentration contributions of components A and B can thus be performed from the analysis of the modulated sum concentration or sum conductivity.

(43) The phase shift of the modulation of the sum concentration or sum conductivity with respect to the phases of the concentrate conveying pumps results from this analysis.

(44) The mean expected value of the sum concentration or of the sum conductivity indicates an over-conveying or an under-conveying of the differing component, i.e. the mean measured value of the sum conductivity or of the sum concentration indicates an over-conveying or an under-conveying of the differing component.

(45) It can thus, for example, not only be seen from state B in FIG. 2 that component A is present at a concentration differing from the expected value, but also that an under-conveying is present with respect to this component.

(46) FIG. 3 shows a multi-component system with modulated conveying of the concentrations of components 1 to N. All the components are conveyed in a main line H in which the only conductivity measurement cell (LF cell) is located. The respective modulations are characteristic for each component with respect to frequency and phase. This characteristic allows an identification of the contribution of a component differing from the expected value.

(47) A compensatory difference of the components which does not result in a change of the mean sum conductivity or sum concentration can even be determined via the determination of the phase shift of the amplitude of the sum conductivity or of the sum concentration to the phase of the concentrate conveying pump.

(48) In accordance with the invention, only one single conductivity sensor or one single concentration sensor or the like is required for the monitoring of the contributions of the individual components, i.e. of the partial components. The components are added to the main line in which the sensor is located via concentrate pumps conveying with modulation.

(49) Instead of a conductivity sensor or of a concentration sensor, any other sensor can also be used which allows a conclusion on the concentrations or conductivities of the components or on the sum concentration or on the sum conductivity.