Medical fluid therapy flow control systems and methods

#The present invention relates to medical systems and more particularly to medical fluid treatment therapies.

#Due to disease, injury or other causes, a person's renal system can fail. In renal failure of any cause, there are several physiological derangements. The balance of water, minerals and the excretion of daily metabolic load are reduced or no longer possible in renal failure. During renal failure, toxic end products of nitrogen metabolism (e.g., urea, creatinine, uric acid, and others) can accumulate in blood and tissues.

#Kidney failure and reduced kidney function have been treated with dialysis. Dialysis removes waste, toxins and excess water from the body that would otherwise have been removed by normal functioning kidneys. Dialysis treatment for replacement of kidney functions is critical to many people because the treatment is life sustaining. One who has failed kidneys could not continue to live without replacing at least the filtration functions of the kidneys.

#FIG. 1 illustrates systems and methods of the present invention for providing pre- and/or postdilution HF/HDF clearance modes, a bolus volume to the patient, a prime to the patient and/or a blood rinseback volume to the patient.

#FIG. 2 illustrates one embodiment of a therapy fluid delivery manifold used in the systems and methods shown in FIG. 1.

#FIGS. 3 and 4 illustrate systems and methods of the present invention for removing ultrafiltrate from the patient and for filtering medical therapy fluid.

#The present invention provides systems and methods for improving medical fluid delivery systems, such as hemodialysis (“HD”), hemofiltration (“HF”) and hemodiafiltration (“HDF”) systems. In various embodiments, systems and methods for selectively performing pre-and postdilution HF and HDF clearance modes are provided. In other embodiments, systems and methods for providing bolus, prime and rinseback fluid volumes during/after HD, HF and HDF therapies are provided. In a further embodiments, improved systems and methods for removing ultrafiltrate from the patient are provided. Still further, the present invention provides an improved filtration configuration and method.

#Referring now to the drawings and in particular to FIG. 1, an HF and/or HDF system 10 is illustrated. System 10 in one embodiment is part of a machine that can perform HD, HF or HDF as selected by a doctor or nurse. The machine is typically used in a treatment center and in one embodiment generates dialysis solution via generation unit 12. One suitable dialysate generation unit 12 for system 10 is described in the maintenance manual for Baxter's System 1000® therapy machine. It should be appreciated from the disclosure herein, however, that the present invention is not limited to dialysate delivery systems or in-center systems but instead applies to any suitable medical fluid therapy treatment.

#Whether system 10 operates in an HF or HDF mode, system 10 includes a dialysate flow path 20 and an extracorporeal or blood circuit 70. In dialysate flow path 20, fluid generated via generation unit 12 is pumped via a supply pump 14 through a supply regulator 16, which sets the maximum pressure of the dialysate in the flow path. Dialysate path 20 employs a number of flow control devices that ensure that the desired amount of fluid is delivered to and removed from the patient (described in commonly owned patent U.S. Pat. No. 5,486,286, the teachings of which are incorporated herein by reference). In particular, dialysate flow path 20 includes a flow equalizer or balancing chamber 30 and an ultrafiltrate flowmeter 50. Flow equalizer 30 includes a pair of fixed volume chambers 32 and 34 that each have a flexible membrane within, creating four variable volume cavities C1, C2, C3 and C4. For fixed chamber 32, the volume in variable cavity C1 is inversely proportional to the volume in variable cavity C2. Likewise, for fixed chamber 34, the volume in variable cavity C3 is inversely proportional to the volume in variable cavity C4.