DIALYSATE FLOW CONTROL

• US 20130056418A1
• Filed: 08/30/2012
• Published: 03/07/2013
• Est. Priority Date: 09/01/2011
• Status: Active Grant

• Current Assignee: Fresenius Medical Care Deutschland GmbH (Fresenius SE & Co. KGaA)
• Original Assignee: Fresenius Medical Care Deutschland GmbH (Fresenius SE & Co. KGaA)
• Inventors: GAGEL, Alfred, KOPPERSCHMIDT, Pascal
• Granted Patent: US 9,724,455 B2
• Time in Patent Office: Days
• US Class Current: 210/646
• CPC Class Codes: A61M 1/16 with membranes
• CPC Class Codes: A61M 1/1605 Physical characteristics of the dialysate fluid
• CPC Class Codes: A61M 1/1615 using measurements made at different flow rates
• CPC Class Codes: A61M 1/36 Other treatment of blood in a by-pass of the natural circulatory system, e.g. temperature adaptation, irradiation ; Extra-corporeal blood circuits
• CPC Class Codes: A61M 1/3609 Physical characteristics of the blood, e.g. haematocrit, urea
• CPC Class Codes: A61M 2205/3317 Electromagnetic, inductive or dielectric measuring means
• CPC Class Codes: A61M 2205/3324 PH measuring means
• CPC Class Codes: A61M 2205/3368 Temperature
• CPC Class Codes: A61M 2205/50 with microprocessors or computers

Abstract

Method and apparatus for controlling the dialysate flow in a dialysis device. A change of the value of a control factor, caused by a variation of a property of the dialysate or of the blood or by a change of the dialysate flow, is determined in order to control the dialysate flow. The control factor is a measure for the exchange of substances via the dialyzer and thus the effectiveness of the dialyzer. If the change of the value of the control factor exceeds a limit, the dialysate flow is increased. On the other hand, the dialysate flow is reduced if the change of the value of the control factor falls short of the limit range.

Claims

1. A method for controlling a dialysate flow, the method comprising:

perfusion of a blood chamber of a dialyzer with blood and of a dialyses chamber, which is separated from the blood chamber by a semi-permeable membrane, with a dialysate,

controlling the dialysate flow through the dialysis chamber of the dialyzer when the value of a control factor is changed and does not lie within a limit range, caused by a variation of a property of the dialysate or of the blood or by a change of the dialysate flow, whereby the control factor is a measure for the exchange of substances via the dialyzer and the controlling includes;

determination of the change of the value of the control factor caused by variation of the property of the dialysate or of the blood or by the change of the dialysate flow, and

increasing the dialysate flow if the change of the value of the control factor exceeds the limit range, or reducing the dialysate flow if the change of the value of the control factor falls below the limit range.

2. The method according to claim 1, wherein the change of the value of the control factor is caused by a change of the dialysate flow, and wherein the control factor comprises a ratio or a difference derived from the values to be assigned after and before the change of the dialysate flow, wherein the values are of a property of the dialysate or of the blood after the dialyzer.

3. The method according to claim 1, wherein the change of the value of the control factor is caused by a variation of a property of the dialysate or the blood, and wherein the control factor has a ratio or a difference derived from values of the property after and before the dialyzer.

4. The method according to claim 3, wherein for determining the change of the value of the control factor, the property of the dialysate or the blood is varied continuously for at least a time interval.

5. The method according to claim 3, wherein the property of the dialysate or the blood is the electrical conductivity or the temperature.

6. The method according to claim 1, wherein the change of the value of the control factor is determined by a derivation of the control factor from the dialysate flow.

7. The method according to claim 1, wherein the limit range corresponds to a range of tolerance around a value of 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20 percent of the value of the control factor per change of the dialysate flow of 100 ml/min.

8. A device for controlling a dialysate flow, comprising

a dialyzer with a blood chamber for perfusion with blood and a dialysis chamber separated from the blood chamber by a semi-permeable membrane for perfusion with a dialysate,

means to generate the dialysate flow through the dialysis chamber,

a unit for the determination of a control factor that is a measure for the exchange of substances over the dialyzer, and

a control facility for controlling the dialysate flow through the dialysis chamber of the dialyzer, if a change of the value of the control factor caused by a variation of a property of the dialysate or of the blood or by a change of the dialysate flow does not lie within a limit range, whereby

the control facility instructs the means for generating the dialysate flow to increase the dialysate flow if the change of the value of the control factor exceeds the limit range, and to reduce the dialysate flow, if the change of the value of the control factor falls below the limit range.

9. The device according to claim 8, wherein the change of the value of the control factor is caused by a change of the dialysate flow and wherein the unit for the determination of the control factor determines the control factor by means of a ratio or a difference derived from values to be assigned after and before the change of the dialysate flow, wherein the values are of a property of the dialysate or of the blood after the dialyzer.

10. The device according to claim 8, wherein the change of the value of the control factor is caused by a variation of a property of the dialysate or the blood and wherein the unit for determining the control factor determines the control factor by means of a ratio or a difference derived from values of the property after and before the dialyzer.

11. The device according to claim 10, wherein the device further has means for continuously varying the property of the dialysate and/or the blood.

12. The device according to claim 10, wherein the property of the dialysate or the blood is the electrical conductivity and the device further has means for determining the values of the electrical conductivity of the dialysate and/or the blood after and before the dialyzer or wherein the property of the dialysate or the blood is the temperature and the device further has means for determining the values of the temperature of the dialysate and/or the blood after and before the dialyzer.

13. The device according to claim 8, wherein the unit for determining the control factor determines the change of the value of the control factor by a derivation of the control factor from the dialysate flow.

14. The device according to claim 8, wherein the limit range corresponds to a range of tolerance around a value of 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20 percent of the value of the control factor per change of the dialysate flow of 100 ml/min.

15. A device for the extra-corporeal blood treatment comprising a device according to claim 8.