Method and device for determining hemodialysis parameters
First Claim
1. A method for determining at least one hemodialysis parameter during an extracorporeal blood treatment using a dialyzer divided by a semipermeable membrane into a blood chamber and a dialysate chamber;
- the method comprising;
passing blood to be treated in an extracorporeal blood circulation path through the blood chamber at a preset blood flow rate;
passing dialysate in a dialysate path from a dialysate source through the dialysate chamber to a drain at a dialysate flow rate;
setting the dialysate flow rate in the dialysate path to a set dialysate flow rate where a concentration of a substance in dialysate flowing out of the dialysate chamber substantially adopts a concentration of the substance in the blood flowing into the blood chamber; and
measuring the concentration of the substance in the dialysate flowing out of the dialysate chamber, the at least one hemodialysis parameter being a function of the concentration of the substance in the dialysate flowing out of the dialysate chamber.
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Accused Products
Abstract
A device and method are described to determine the concentration of a substance in blood flowing through a blood chamber of a dialyzer during extra corporeal blood treatment. The flow rate of dialysate flowing through the dialysate chamber of the dialyzer is reduced to a value at which the concentration of the substance at the outlet of the dialysate chamber is essentially the same as the concentration of that same substance in the blood at the inlet of the blood chamber. The concentration measurement can be carried out without interrupting the flow of dialysate.
152 Citations
28 Claims
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1. A method for determining at least one hemodialysis parameter during an extracorporeal blood treatment using a dialyzer divided by a semipermeable membrane into a blood chamber and a dialysate chamber;
- the method comprising;
passing blood to be treated in an extracorporeal blood circulation path through the blood chamber at a preset blood flow rate; passing dialysate in a dialysate path from a dialysate source through the dialysate chamber to a drain at a dialysate flow rate; setting the dialysate flow rate in the dialysate path to a set dialysate flow rate where a concentration of a substance in dialysate flowing out of the dialysate chamber substantially adopts a concentration of the substance in the blood flowing into the blood chamber; and measuring the concentration of the substance in the dialysate flowing out of the dialysate chamber, the at least one hemodialysis parameter being a function of the concentration of the substance in the dialysate flowing out of the dialysate chamber. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
- the method comprising;
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16. A blood treatment device comprising:
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a dialyzer including a blood chamber and a dialysate chamber separated by a semipermeable membrane, the blood chamber being connected to an extracorporeal blood circulation path, the dialysate chamber being connected to a dialysate path; a blood pump connected to the extracorporeal blood circulation path; a dialysate pump connected to the dialysate path; and an apparatus for determining at least one hemodialysis parameter during an extracorporeal blood treatment, the apparatus including; a measuring device disposed in the dialysate path downstream from the dialysate chamber for measuring a concentration of a substance in dialysate flowing out of the dialysate chamber; a control unit for determining a concentration of the substance in blood flowing into the blood chamber by reducing a pumping rate in the dialysate path of the dialysate pump during the dialysis treatment, for a preset time interval, from a preset value to a reduced pumping rate in the dialysate path at which the concentration of the substance in the dialysate flowing out of the dialysate chamber as measured with the measuring device substantially adopts the concentration of the substance in blood flowing into the blood chamber, and for, after the preset time interval, raising the pumping rate of the dialysate pump to the preset value; and an analyzer unit for receiving an output signal of the measuring device, the analyzer unit being controlled by the control unit so that the analyzer unit records the concentration of the substance in the dialysate flowing out of the dialysate chamber before the control unit sets the pumping rate of the dialysate pump to the preset value, the at least one hemodialysis parameter being a function of the concentration of the substance in the dialysate flowing out of the dialysate chamber. - View Dependent Claims (17, 18)
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19. A method for determining at least one hemodialysis parameter in vivo based on a concentration of a substance in an extracorporeal blood circulation path connected to a first chamber of a dialyzer, the first chamber being divided by a semipermeable membrane from a second chamber of the dialyzer, a dialysate circuit being connected to the second chamber, the method comprising:
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interrupting dialysate flow through the second chamber for a preset time interval to establish a steady state so that dialysate in the second chamber substantially adopts, at least in a partial volume of the second chamber, a concentration of a substance in blood flowing through the extracorporeal blood circulation path into the first chamber, the interrupting of the dialysate flow occurring without an interruption of a blood flow; flushing out of the second chamber a residual amount of the dialysate in the second chamber of the dialyzer after establishment of the steady state; and measuring the concentration of the substance in the dialysate in the second chamber after the establishing of the steady state by measuring downstream from the dialyzer the concentration of the substance in the residual amount of the dialysate flowing out of the second chamber, the at least one hemodialysis parameter being a function of the concentration of the substance in the second chamber after the establishing of the steady state. - View Dependent Claims (20, 21, 22, 23, 24)
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25. A blood treatment device comprising:
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a dialyzer including a blood chamber and a dialysate chamber separated by a semipermeable membrane, the blood chamber being capable of being connected to a dialysis patient via an extracorporeal blood circulation path, blood flowing in and out of the blood chamber at blood flow rate, the dialysate chamber being connected to a dialysate circuit, dialysate flowing in and out of the dialysate chamber at a dialysate flow rate; at least one sensor for measuring a concentration of a substance in dialysate flowing out of the dialyzer, at least one of the at least one sensor being disposed downstream from the dialyzer; an interrupting device for interrupting dialysate flow through the dialyzer; a control/analyzer unit connected to the interrupting device for receiving at least an output measurement signal of the at least one sensor, the control/analyzer unit be capable of, at a time when the concentration of the substance in blood of a patient is determined, sending a signal to the interrupting device so that there is no flow in the dialysate chamber and a residual dialysate is maintained in the dialysate chamber, and, after a preset time interval to establish a steady state so that at least part of the residual dialysate substantially adopts the concentration of the substance in blood flowing into the blood chamber, of sending a signal to the interrupting device for reconnecting the dialyzer to the dialysate circuit to flush out the residual dialysate, and then, after a time interval determined by a flow rate of the dialysate and a distance of an outlet of the dialyzer from the at least one sensor, of analyzing the output measurement signal of the at least one sensor to determine the concentration of the substance in the residual dialysate. - View Dependent Claims (26, 27, 28)
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Specification