DIALYSIS SYSTEM WITH ULTRAFILTRATION CONTROL
Systems and methods are disclosed for performing hemodialysis that include fluid handling systems that provide accurate control over the type and level of hemodialysis being performed. The system includes a first pump for pumping dialysate into a dialyzer and a second pump for pumping dialysate out of the dialyzer. The system also includes a third pump that provides improved control of a level of ultrafiltration, hemodiafiltration, or both.
1 . A method of performing dialysis, comprising:
operating a first pump to pump dialysate at a first flow rate through a fluid inlet pathway into a dialyzer;
operating a second pump to pump the dialysate through a fluid outlet pathway out of the dialyzer;
operating a third pump to pump the dialysate through the fluid outlet pathway in cooperation with the second pump, wherein the second and third pumps cooperate to collectively achieve a second flow rate through the fluid outlet pathway from the dialyzer;
pumping blood through the dialyzer in communication with the dialysate such that the dialyzer dialyzes the blood; and
varying the pumping speed of at least one of the first pump, second pump and third pump to allow the dialyzer to individually perform hemodialysis, ultrafiltration and hemodiafiltration based on relative pumping speeds between the first pump, second pump and third pump.
2 . The method of claim 1 , wherein the first, second and third pumps operate to maintain balance between the fluid flow rates in the inlet pathway and outlet pathway such that substantially no fluid is added to or removed from the blood during operation.
3 . The method of claim 1 , wherein the first, second and third pumps operate to maintain balance between the fluid flow rates in the inlet pathway and outlet pathway such that a desired rate of fluid addition to the blood during operation is achieved.
4 . The method of claim 1 , wherein the first, second and third pumps operate to maintain balance between the fluid flow rates in the inlet pathway and outlet pathway such that a desired amount of fluid is removed from the blood during operation.
5 . The method of claim 1 , wherein the first, second and third pumps operate to maintain balance between the fluid flow rates in the inlet pathway and outlet pathway such that a desired amount of fluid is added to the blood during a time span of operation.
6 . The method of claim 1 , wherein the first, second and third pumps operate to maintain balance between the fluid flow rates in the inlet pathway and outlet pathway such that amount of fluid is removed to the blood during a time span of operation.
7 . The method of claim 1 , wherein the first, second and third pumps operate to achieve a desired level of hemodiafiltration by cycling the third pump between a lower speed and a higher speed substantially without a net addition of fluid to the blood.
8 . The method of claim 1 , wherein the first, second and third pumps operate to achieve a desired level of hemodiafiltration and a desired rate of fluid addition to the blood by cycling the third pump between a lower speed and a higher speed.
9 . The method of claim 1 , wherein the first, second and third pumps operate to achieve a desired level of hemodiafiltration and a desired rate of fluid removal from the blood by cycling the third pump between a lower speed and a higher speed.
10 . A method of performing dialysis, comprising:
providing a dialysis system having an inlet conduit through which fluid flows in an inward direction toward a dialyzer and an outlet conduit through which fluid flows in an outward direction from the dialyzer;
pumping fluid through the inlet conduit using a first pump;
pumping fluid through the outlet conduit using a second pump;
using a third pump to supplement the pumping of the second pump through the outlet conduit; and
varying the pumping speed of at least one of the first pump, second pump and third pump to allow the dialyzer to individually perform hemodialysis, ultrafiltration and hemodiafiltration based on relative pumping speeds between the first pump, second pump and third pump.
11 . A method as in claim 10 , further comprising measuring a first fluid pressure in the inlet conduit and a second fluid pressure in the outlet conduit and adjusting a pump speed of the third pump based on the first and second fluid pressures.
12 . A method as in claim 10 , wherein adjusting a pump speed of the third pump based on the first and second fluid pressures comprises adjusting the pump speed of the third pump based on a pressure differential between the first fluid pressure and the second fluid pressure.
13 . A method as in claim 10 , wherein the fluid is dialysate and further comprising pumping blood through the dialyzer to achieve dialysis of the blood, and further comprising operating the third pump in a manner such that no fluid is added or removed from the blood during dialysis.
14 . A method as in claim 10 , wherein the fluid is dialysate and further comprising pumping blood through the dialyzer to achieve dialysis of the blood, and further comprising operating the third pump in a manner such that fluid is added to the blood from the dialysate during dialysis.
15 . A method as in claim 10 , wherein the fluid is dialysate and further comprising pumping blood through the dialyzer to achieve dialysis of the blood, and further comprising operating the third pump in a manner such that fluid is removed from dialysate into the blood during dialysis.
16 . A method as in claim 10 , wherein the fluid is dialysate and further comprising pumping blood through the dialyzer to achieve dialysis of the blood, and further comprising operating the third pump in a manner such that fluid is removed from the blood into the dialysate, and then operating the third pump in a manner such that fluid is added into the blood from the dialysate.
17 . A method as in claim 16 , wherein there is substantially no net gain of fluid into the blood and no loss of fluid from the blood over a predetermined span of time.
18 . A method as in claim 10 , wherein a first valve and a second valve control the flow of fluid through the bypass conduit.