Method and device for the removal of partially protein bound substances
A method and a device to increase the efficiency of dialysis for the removal from blood of substances that are more or less tightly bound to carriers such as albumin. According to the invention this is accomplished by a simultaneous significant increase of the flow rate of the dialysis fluid and of the area of the membrane that separates the blood from the dialysis fluid, compared to conventional dialysis.
1. A method for removing partially carrier bound substances from blood comprising a blood circuit, a fluid circuit, and a filter having a semipermeable membrane separating a fluid compartment from a blood compartment, the method comprising:
directing a mixture of blood and a cleaning fluid through the blood compartment; and
applying a pressure gradient across the membrane to create an ultrafiltration into the fluid compartment equal in size to the sum of a flow rate of the cleaning fluid and a desired weight loss rate of a patient, wherein
a water permeability coefficient L p A of the filter is at least 10 ml/min/mm Hg;
the cleaning fluid flow rate is at least 1000 ml/min; and
a ratio between the cleaning fluid flow rate and a blood flow rate is at least 5.
2. A method according to claim 1 , wherein the filter is replaced by several filters arranged in series or parallel, or a combination thereof.
3. A method according to claim 1 or 2 , wherein the blood is heated before being returned to the patient.
4. A method according to claim 3 , wherein the heating of the blood is performed in a final dialyzer along a blood path before the blood is returned to the patient.
5. A device configured to remove partially carrier bound substances from blood comprising a blood circuit, a fluid circuit, and a filter having a semipermeable membrane separating a fluid compartment from a blood compartment, provided with
means for mixing blood and a cleaning fluid and directing said mixture through the blood compartment, and
means to apply a pressure gradient across the membrane to create an ultrafiltration into the fluid compartment equal in size to the sum of a flow rate of the cleaning fluid and a desired weight loss rate of the patient, wherein
the filter has a water permeability coefficient L A of at least 10 ml/min/mm Hg;
the device is configured to sustain a cleaning fluid flow rate of at least 1000 ml/min to the filter; and
the device is configured to maintain a ratio between the cleaning fluid flow rate and a blood flow rate to the filter of at least 5.
6. A device according to claim 5 , wherein the filter is replaced by several filters arranged in series or parallel, or a combination thereof.
7. A device according to claim 5 or 6 , wherein a heater is arranged for heating the blood before it is returned to the patient.
8. A device according to claim 7 , wherein the heater is a final dialyzer along the blood path before the blood is returned to the patient.