DIALYSIS DEVICE

Abstract

The invention relates to a dialysis device having an extracorporeal blood system, a dialyzing fluid system, a dialyzer and a control unit, wherein the dialysis device has a heating mechanism for heating the blood in the extracorporeal blood system before entry into the dialyzer or in the dialyzer as well as a cooling mechanism for cooling the blood in the extracorporeal blood system after exiting the dialyzer and wherein the control unit is configured such that the blood is heated before entry into the dialyzer or in the dialyzer to a dialysis temperature which is above the body temperature of the patient and is cooled back to the body temperature of the patient after exiting the dialyzer.

Claims

1. A dialysis device comprising an extracorporeal blood system, a dialyzing fluid system, a dialyzer and a control unit, characterized in that the dialysis device has a heating mechanism for heating the blood in the extracorporeal blood system before entry into the dialyzer or in the dialyzer as well as a cooling mechanism for cooling the blood in the extracorporeal blood system after exiting the dialyzer; and in that the control unit is configured such that the blood is heated before entry into the dialyzer or in the dialyzer to a dialysis temperature which is above the body temperature of the patient and is cooled back to the body temperature of the patient after exiting the dialyzer.

2. A dialysis device in accordance with claim 1, characterized in that the dialysis temperature is between 37 C. and 46 C., preferably between 40 C. and 46 C., and further preferably between 42 C. and 45 C.

3. A dialysis device in accordance with claim 1, characterized in that the heating mechanism comprises a heating apparatus arranged at the feed side of the dialyzer in the dialyzing fluid system; and in that the control unit is configured such that the dialyzing fluid is heated before entry into the dialyzer to a temperature which is larger than or at least equal to the dialysis temperature.

4. A dialysis device in accordance with claim 1, characterized in that the dialysis device furthermore has a substitution fluid system which comprises a pre-dilution line opening at the feed side of the dialyzer into the extracorporeal blood system and/or a post-dilution line opening at the return side of the dialyzer into the extracorporeal blood system.

5. A dialysis device in accordance with claim 4, characterized in that the heating mechanism comprises a heating apparatus arranged at the feed side of the opening of the pre-dilution line in the substitution fluid system; and in that the control unit is configured such that the substitution fluid is heated before entry into the extracorporeal blood system through the pre-dilution line to a temperature which is larger than or at least equal to the dialysis temperature.

6. A dialysis device in accordance with claim 5, characterized in that the cooling mechanism comprises a cooling apparatus arranged at the feed side of the opening of the post-dilution line in the substitution fluid system; and in that the control unit is configured such that the substitution fluid is cooled before entry into the extracorporeal blood system through the post-dilution line to a temperature which is less than or at a maximum equal to body temperature.

7. A dialysis device in accordance with claim 5, characterized in that the cooling mechanism has a branch for substitution fluid arranged at the feed side of the heating apparatus in the substitution fluid system, the temperature of the substitution fluid being less than or at a maximum equal to body temperature; and in that the control unit is configured such that the substitution fluid is branched off before entry into the heating apparatus and is not heated up to body temperature through the post-dilution line before entry into the extracorporeal blood system.

8. A dialysis device in accordance with claim 1, characterized in that the heating mechanism comprises a heating apparatus arranged at the feed side of the dialyzer in the blood system; and/or in that the cooling mechanism comprises a cooling apparatus arranged at the return side of the dialyzer in the blood system.

9. A dialysis device in accordance with claim 3, characterized in that the heating apparatus is a flow heater arranged at a line of the respective fluid system; and/or in that the heating apparatus comprises a heat exchanger, for example a spiral heat exchanger, a Peltier element and/or a heating pack as a heating element.

10. A dialysis device in accordance with claim 3, characterized in that the cooling apparatus is a flow cooler arranged at a line of the respective fluid system; and/or in that the cooling apparatus comprises a heat exchanger, for example a spiral heat exchanger, a Peltier element and/or a cooling pack as a cooling element.

Description

[0025] Further details and advantages of the invention result from the embodiments represented in the following with reference to the Figures. There are shown in the Figures:

[0026] FIG. 1: a modeled representation of the change of the diffusion coefficient D in an aqueous solution according to the Stokes-Einstein equation;

[0027] FIG. 2: a schematic representation of an embodiment of a dialysis device in accordance with the invention;

[0028] FIG. 3: a schematic representation of a further embodiment of a dialysis device in accordance with the invention;

[0029] FIG. 4: a schematic representation of a further embodiment of a dialysis device in accordance with the invention; and

[0030] FIG. 5: a schematic representation of a further embodiment of a dialysis device in accordance with the invention.

[0031] A modeled representation of the change of the diffusion coefficient D in an aqueous solution according to the Stokes-Einstein equation is shown in FIG. 1. The Stokes-Einstein equation describes the diffusion coefficient in dependence on the temperature T, on the viscosity of the solvent and on the radius r of the diffusing molecule.

D=k.sub.B.Math.T/6.Math..Math..Math.r=const.Math.T/(T)

[0032] The viscosity of the water (plasma) is likewise temperature-dependent. In the representation in accordance with FIG. 1, the ratio T/ and its relative change with respect to 37 C. is shown as a function of the temperature. With a temperature increase from 37 C. to 46 C. (T=+9K), an increase of the diffusion coefficient D by 20% accordingly results for all molecules.

[0033] A first embodiment of a dialysis device in accordance with the invention is shown schematically in FIG. 2.

[0034] The dialysis device comprises an extracorporeal blood circuit 1 and a dialyzing fluid circuit 2 which come into contact with one another at a dialyzer 3. The dialyzer 3 comprises a semipermeable membrane 4 which separates a blood chamber 5, which forms a part of the extracorporeal blood circuit 1, and a dialyzing fluid chamber 6, which forms a part of the dialyzing fluid circuit 2, from one another. The flow directions of the blood and of the dialyzing fluid in the different chambers 5 and 6 of the dialyzer 3 are opposite directions. The flow directions in the circuits are indicated by arrows in the Figure.

[0035] A blood pump 8 is located in the arterial blood line 7 and a drip chamber 10 is located in the venous blood line 9. The arterial port and the venous port 12 for connection to the patient are marked by the reference numerals 11 and 12.

[0036] The feed line 13 of the dialyzing fluid circuit 2 is connected to a dialyzing fluid source 14. The source can, for example, be a reservoir individual to a machine or a continuous mixing unit individual to a machine. It is furthermore conceivable that the source 14 represents a central supply unit of a dialysis center. The return line 15 of the dialyzing fluid circuit 2 is connected to a drain 16.

[0037] The dialysis device furthermore has a control unit 17 which inter alia regulates the flow rates in the extracorporeal blood circuit 1 and in the dialyzing fluid circuit 2 using the pump 8 and further actuators not shown in FIG. 2, but familiar to the skilled person.

[0038] In accordance with the invention, the dialysis device has a heating mechanism for heating the blood on passing through the dialyzer 3. In the embodiment shown, the heating mechanism comprises a heating apparatus 18 which is arranged in the source 14 or in the feed lines 13 and which (not shown in the Figure) is connected to the control unit 17. This heating apparatus 18 is controlled by the control unit 17 such that dialysis fluid is elevated to a temperature above the body temperature of the patient before it enters the dialyzing fluid chamber 6 of the dialyzer 3. The blood is continuously heated on passing through the blood chamber 5 of the dialyzer 3 by a heat exchange at the semipermeable membrane 4 until it reaches a dialysis temperature close to the venous outlet of the dialyzer 3 which is preferably above 40 C. An increased purification performance is thereby achieved at least in the venous half of the dialyzer 3 due to the previously described effects. The temperature of the dialyzing fluid entering into the dialyzer 3 can be monitored, for example, using a temperature sensor not shown in the Figure which is located in the feed line 13 of the dialyzing fluid circuit 2, preferably close to the dialyzer 3, and which is likewise connected to the control unit 17.

[0039] To cool the blood back to body temperature, which was heated in the dialyzer 3 to a dialysis temperature above the body temperature of the patient, before reinfusion into the patient at the venous port 12, the dialysis device furthermore has a cooling mechanism which comprises a heat exchanger 19 in the venous line 9. The heat exchanger 19 can, for example, be configured as a spiral heat exchanger, wherein the blood is brought into heat-conductive contact with a cooling fluid which has a temperature below body temperature. The heat exchanger or the fluid pump for the cooling fluid is likewise connected to the control unit 17. To monitor the blood temperature before reinfusion at the venous port 12, a temperature sensor which is not shown in the Figure and which is likewise connected to the control unit 17 can be present in the venous line 9, preferably close to the venous port 12 and in any case between the heat exchanger 19 and the venous port 12.

[0040] A further embodiment of a dialysis device in accordance with the invention is shown in FIG. 3, with the same parts being provided with the same reference numerals.

[0041] In this respect, the cooling mechanism comprises a post-dilution line 20 which branches off from the feed line 13 at a point 21. A fluid pump 22 is arranged within the post-dilution line. This post-dilution line 20 opens into the venous line 9 at the drip chamber 10.

[0042] In this embodiment, a heating apparatus 23 is provided in the feed line 13 between the branching point 21 and the dialyzer 3. It is thus possible to further increase the temperature of the dialyzing fluid which is supplied to the dialyzer 3 after the branching off of the substitution solution for the post-dilution. Provision can be made to this extent that the dialyzing fluid is not heated or is at least not heated up to body temperature during the provision in the source 14 and is branched off into the post-dilution line 20 at the branching point 21 in this still cool state. An increase of the temperature to above body temperature only takes place between the branching point 21 and the dialyzer 3 using the heating apparatus 23 so that the heating effects of the blood are adopted in the dialyzer 3 which have already been shown in connection with the embodiment in accordance with FIG. 1.

[0043] The heating apparatus 23 and the pump 22 are connected to the control unit 17.

[0044] In contrast to the apparatus in accordance with FIG. 1, the cooling of the blood after leaving the dialyzer 3 does not take place by an addition cooling unit 19, but rather by the supply of substitution solution which has a temperature which is below body temperature. The advantage of this solution is that no heating, element and/or cooling element is required at the extracorporeal blood circuit 1.

[0045] A further embodiment of the invention is shown in FIG. 4, wherein the same parts are again marked by identical reference numerals. This embodiment is similar to the embodiment in accordance with FIG. 3 with the sole difference that a cooling apparatus 24 is arranged in the post-dilution line 20 instead of the heating apparatus 23 in the fed line 13. The dialyzing fluid is thus, as was also the case in the embodiment in accordance with FIG. 2, already increased above body temperature already during the provision and is also branched off at the branching point 21 into the post-dilution line 20 also at an elevated temperature. The dialyzing fluid or substitution fluid is subsequently cooled by the cooling apparatus 24 in the post-dilution line 20 before it is introduced into the venous line 9 of the extracorporeal blood circuit 1. This embodiment has the advantage with respect to the embodiment in accordance with FIG. 3 that an improved regulating capability of the cooling power is present by using the selective cooling of the substitution fluid in the post-dilution line 20.

[0046] The cooling apparatus 24, the heating apparatus 18 and the pump 22 are connected to the control unit 17.

[0047] In the embodiment in accordance with FIGS. 3 and 4, a temperature sensor can be present in the post-dilution line 20, preferably close to the drip chamber 10, to be able to determine the temperature of the substitution solution to be fed into the venous line 9. This temperature sensor is in turn connected to the control unit 17.

[0048] FIG. 5 shows a further embodiment of a dialysis device in accordance with the invention, wherein the difference between the embodiment in accordance with FIG. 2 lies in the fact that a pre-dilution line 25 is provided by which substitution solution is branched off from the source 14 and is admixed Into the arterial line 7 at a mixing point 26 between the pump 8 and the dialyzer 3.

[0049] A pump 27 is located in the pre-dilution line 25. There is the possibility in this embodiment to introduce substitution fluid heated in the source 14 to a temperature above the body temperature of the patient into the arterial line 7 and thus already to heat the blood to a dialysis temperature of, for example, more than 40 C. before entry into the dialyzer 3. The treatment efficiency can be increased to this extent over the total dialyzer in this manner. A further heating by the use of a dialyzing fluid heated above body temperature at the dialyzing fluid side 6 of the dialyzer 3 is additionally possible.

[0050] Provision is preferably made in this embodiment to provide a temperature sensor close to the injection point 26 in the pre-dilution line 25 and to connect said temperature sensor to the control unit 17 to be able to monitor the temperature of the injected substitution solution. The pump 27 is likewise connected to the control unit 17.