Device and method for determining a dialysis fluid flow rate for extracorporeal blood treatment
The present invention relates to a device and to a method for determining the dialysis fluid flow rate for an extracorporeal blood treatment device. The dialysis fluid flow rate Q d is determined in accordance with the blood flow rate Q b or the blood flow rate Q b is determined in accordance with the dialysis fluid flow rate Q d , wherein by increasing about a specific value, the increase of a variable characterising the efficiency of the blood treatment, in particular clearance K, does not exceed the specific value. The present invention also relates to a blood treatment device comprising a device for determining the dialysis fluid flow rate or blood flow rate and to a method for operating an extracorporeal blood treatment device. As a result, an optimal dialysis fluid flow rate and/or blood flow rate calculates the requirement in accordance with a high efficiency of the dialysis treatment and in accordance with a reduced consumption of the dialysis liquid.
1. A system for pre-setting a flow rate for an extracorporeal blood-treating apparatus comprising a dialyser divided into a blood chamber and a dialysis chamber by a semi-permeable membrane, wherein blood flows through the blood chamber and dialysis fluid flows through the dialysis chamber, said system comprising
a means for selecting an optimum flow rate, said means for selecting an optimum flow rate being selected from the group consisting of:
a means for selecting an optimum dialysis fluid flow rate Q dopt as a function of a pre-set blood flow rate Q b , wherein Q dopt for the pre-set blood flow rate Q b is a solution for Q dopt such that if Q dopt were increased by a first given amount, a metric characteristic of the effectiveness of the blood treatment would increase by approximately a second given amount; and
a means for selecting an optimum blood flow rate Q dopt as a function of a pre-set dialysis fluid flow rate Q d , wherein Q bopt for the pre-set dialysis fluid flow rate Q d is a solution for Q bopt such that if Q bopt were increased by a third given amount, a metric characteristic of the effectiveness of the blood treatment would increase by approximately a fourth given amount,
wherein the means for selecting Q dopt or the means for selecting Q bopt is a calculating unit configured such that Q dopt or Q bopt is calculated from a mathematical equation by an iterative approximate solution method.
2. The system of claim 1 , wherein the metric characteristic of the effectiveness is a clearance K of the dialysis treatment.
3. The system of claim 2 , configured such that Q bopt or Q dopt is selected as a function of a metric characteristic of the dialyser.
4. The system of claim 1 , configured such that Q bopt or Q dopt is selected as a function of a metric characteristic of the dialyser.
5. The system of claim 4 , wherein the metric characteristic of the dialyser is a mass transfer coefficient k 0 A of the dialyser.
6. The system of claim 5 , further comprising
an input unit for presetting various modes of treatment in which the effectiveness of the blood treatment differs, configured such that for a first given mode of treatment and a second given mode of treatment:
a ratio of the first given amount to the second given amount for the first given mode of treatment differs from a ratio of the first given amount to the second given amount for a second given mode of treatment; or
a ratio of the third given amount to the fourth given amount for the first given mode of treatment differs from a ratio of the third given amount to the fourth given amount for the second given mode of treatment.
7. The system of claim 1 , further comprising:
an input unit for presetting various modes of treatment in which the effectiveness of the blood treatment differs, configured such that for a first given mode of treatment and a second given mode of treatment:
a ratio of the first given amount to the second given amount for the first given mode of treatment differs from a ratio of the first given amount to the second given amount for the second given mode of treatment; or
a ratio of the third given amount to the fourth given amount for the first given mode of treatment differs from a ratio of the third given amount to the fourth given amount for the second given mode of treatment.
8. The system of claim 1 , wherein the mathematical equation is a multi-order polynomial.
9. A blood-treating apparatus for the extracorporeal treatment of blood, comprising:
a dialyser divided by a semi-permeable membrane into a blood chamber and a dialysis chamber, wherein blood flows through the blood chamber at a pre-set blood flow rate Q b , or a dialysis fluid flows through the dialysis chamber a pre-set dialysis fluid rate Q d ; and
the system for pre-setting a flow rate of claim 1 .
10. The blood-treating apparatus of claim 9 , further comprising:
a control unit for pre-setting Q d or Q b .
11. The blood-treating apparatus of claim 10 , further comprising:
at least one of:
a dialysis-fluid pump for pumping the dialysis fluid, and
a blood pump for pumping blood,
wherein the control unit is configured to set the speed of the dialysis fluid pump at the pre-set dialysis flow rate Q d or to set the speed of the blood pump at the pre-set blood flow rate Q b .
12. A method for pre-setting a dialysis fluid flow rate or a blood flow rate for an extracorporeal blood-treating apparatus comprising a dialyser divided into a blood chamber and a dialysis chamber by a semi-permeable membrane, wherein the blood flows through the blood chamber and dialysis fluid flows through the dialysis chamber, the method comprising:
selecting an optimum dialysis fluid flow rate Q dopt as a function of a pre-set blood flow rate Q b at a pre-set blood flow rate Q b such that if Q dopt were increased by a first given amount, a metric characteristic of the effectiveness of the blood treatment would increase by approximately a second given amount; or
selecting an optimum blood flow rate Q bopt as a function of a pre-set dialysis fluid flow rate Q d at a pre-set dialysis fluid flow rate Q d such that if Q bopt were increased by a third given amount, a metric characteristic of the effectiveness of the blood treatment would increase by approximately a fourth given amount,
wherein Q dopt or Q bopt is calculated from a mathematical equation by an iterative approximate solution method.
13. The method of claim 12 , wherein the metric characteristic of the effectiveness is a clearance K of the dialysis treatment.
14. The method of claim 12 , further comprising selecting Q bopt or Q dopt as a function of a metric characteristic of the dialyser.
15. The method of claim 14 , wherein the metric characteristic of the dialyser is a mass transfer coefficient k 0 A of the dialyser.
16. The method of claim 12 , further comprising:
presetting at least two modes of treatment in which the effectiveness of the blood treatment differs, such that for a first given mode of treatment and a second given mode of treatment:
a ratio of the first given amount to the second given amount for the first given mode of treatment differs from a ratio of the first given amount to the second given amount for the second given mode of treatment; or
a ratio of the third given amount to the fourth given amount for the first given mode of treatment differs from a ratio of the third given amount to the fourth given amount for the second given mode of treatment.
17. The method of claim 12 , wherein the mathematical equation is a multi-order polynomial.
18. A method comprising:
performing the method for pre-setting the dialysis fluid flow rate or the blood flow rate of claim 12 ; and
operating the extracorporeal blood-treating apparatus comprising a dialyser divided by a semi-permeable membrane into a blood chamber and a dialysis chamber, wherein blood flows through the blood chamber at the pre-set blood flow rate Q b , or a dialysis fluid flows through the dialysis chamber at the pre-set dialysis fluid rate Q d .