Control architecture and method of blood processing system

Abstract

To provide various systems and methods capable of executing hemodialysis more efficiently, easily, and / or at lower costs.SOLUTION: A dialysis system includes a plurality of actuators that work together so as to fulfill a dialysis function, and a plurality of sensors that work together so as to monitor the dialysis function. According to one embodiment, the hemodialysis system includes a user interface model layer, a treatment layer below the user interface model layer, and a machine layer below the treatment layer. The user interface model layer is configured so as to manage the state of a graphical user interface, and receive the input from the graphical user interface. The treatment layer is configured so as to execute a state machine for creating a treatment command based at least partially on the input from the graphical user interface. The machine layer is configured so as to provide an actuator with a command based on the treatment command.SELECTED DRAWING: Figure 66

Description

[Technical field]

[0001] The present invention relates to hemodialysis and similar dialysis systems, i.e., systems for treating blood and other bodily fluids outside the body. In embodiments, the systems include various systems and methods that can make hemodialysis more efficient, easier, and / or less costly. [Background technology]

[0002] Many factors make hemodialysis inefficient, difficult, and costly. These factors include the complexity of hemodialysis, the safety issues associated with hemodialysis, and the large volume of dialysate required for hemodialysis. Furthermore, hemodialysis typically requires skilled personnel and is performed in a dialysis center. Thus, improvements in the ease and efficiency of the dialysis process impact the cost of the procedure and patient outcomes.

[0003] FIG. 1 is a schematic diagram of a hemodialysis system. The system 5 includes two flow paths: a blood flow path 10 and a dialysate flow path 20. Blood is pumped from a patient. A blood flow pump 13 causes the blood to flow around the blood flow path 10, pumping the blood from the patient, thereby forcing the blood through a dialyzer 14 and returning the blood to the patient. Optionally, the blood passes through other elements, such as a filter and / or air trap 19, before being returned to the patient. Additionally, in the example, an anticoagulant is supplied from an anticoagulant supply 11 through an anticoagulant valve 12.

[0004] A dialysate pump 15 pumps dialysate from a dialysate supply 16 and passes the dialysate through the dialyzer 14. The dialysate then passes through a relief valve 18 and / or back to the dialysate supply through the dialysate pump 15. A dialysate valve 17 controls the flow of dialysate from the dialysate supply 16. The dialyzer is configured so that blood from the blood flow circuit flows through small tubes and dialysate circulates around the outside of the tubes. Therapy occurs as waste molecules (e.g., urea, creatinine, etc.) and water pass from the blood through the walls of the tubes and into the dialysate. At the end of treatment, the dialysate is drained. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] US Patent Application Publication No. 2002 / 056672 Summary of the Invention [Problem to be solved by the invention]

[0006] It is an object of the present invention to provide various systems and methods that can make hemodialysis more efficient, easier, and / or less costly. [Means for solving the problem]

[0007] The present invention relates to hemodialysis systems and similar dialysis systems. In embodiments, the subject matter of the present invention includes related products, alternative solutions to a given problem, and / or a number of different uses for one or more of the systems or products. Although the various systems and methods disclosed herein are described in the context of hemodialysis, the various systems and methods disclosed herein may be suitable for other dialysis systems and / or any extracorporeal system capable of treating blood or other bodily fluids, such as hemofiltration, hemodiafiltration, and the like.

[0008] In one embodiment, the system includes four flow paths: blood, dialysate in, dialysate out, and a dialysate mix flow path. In an embodiment, the four flow paths are combined in a single cassette. In another embodiment, the four flow paths are located in respective cassettes. In yet another embodiment, two or more flow paths are included in a single cassette. In one embodiment, a hemodialysis system is provided having at least two flow paths, the two flow paths being integrally mounted in 1) a blood flow pump cassette, 2) an internal dialysate cassette, 3) an external dialysate cassette, and 4) a mixing cassette. The cassettes are in communication with each other. In an embodiment, one or more aspects of these cassettes are incorporated in a single cassette. In yet another embodiment, a hemodialysis system is provided including a blood flow path in which untreated blood is pumped from a patient, passed through a dialyzer, and treated blood is returned to the patient. The blood flow path includes at least one blood flow pump mounted in a removable cassette. The hemodialysis system may further include a first receiving structure for receiving the cassette of the blood flow path, a dialysate flow path through which dialysate flows from a dialysate supply through the dialyzer, a second receiving structure for receiving the dialysate flow path, and a control fluid path for delivering control fluid from a drive mechanism to the cassette to drive each of the blood flow pumps and the dialysate pumps. In an embodiment, the dialysate flow path may include at least one dialysate pump provided in a removable cassette.

[0009] In yet another embodiment, a hemodialysis system is disclosed. In this embodiment, the hemodialysis system includes a blood flow path through which untreated blood is pumped from a patient, passes through a dialyzer, and treated blood is returned to the patient. The blood flow path includes at least one blood valve. The hemodialysis system further includes a blood valve, a dialysate mixing system (including at least one dialyzer valve) in communication with the dialyzer, and a control fluid path that delivers a control fluid from a drive mechanism to the blood valve to drive a heating means or heater for heating the dialysate.

[0010] In yet another embodiment, a hemodialysis system is disclosed that includes a blood flow path through which untreated blood is pumped from a patient and passed through a dialyzer, and treated blood is returned to the patient. The blood flow path includes at least one blood flow pump. The hemodialysis system further includes a dialysate flow path through which dialysate flows from a dialysate supply and through the dialyzer. The dialysate flow path includes at least one pneumatic pump. In one aspect, the invention relates to a hemodialysis system. In an embodiment, the hemodialysis system includes a blood flow path, a first cassette forming an internal dialysate flow path, a dialyzer in communication with the blood flow path and the internal dialysate flow path, a second cassette forming an external dialysate flow path, and a membrane connecting the first cassette to the second cassette.

[0011] In yet another embodiment, the hemodialysis system includes a blood flow path, an internal dialysate flow path, a dialysis device in communication with the blood flow path and the internal dialysate flow path, an external dialysate flow path, a membrane communicating between the internal dialysate flow path and the external dialysate flow path, a first dialysate pump that pumps dialysate from the internal dialysate flow path, and a second dialysate pump that pumps dialysate from the external dialysate flow path, the second dialysate pump and the first dialysate pump being operably connected such that the flow in the internal dialysate flow path is approximately equal to the flow in the external dialysate flow path.

[0012] In yet another embodiment, the dialysate system includes a blood flow path through which blood is pumped from a patient and passed through the dialyzer, a dialysate flow path through which dialysate flows from a dialysate supply through the dialyzer, and in one embodiment, the dialysate flow path includes a balancing cassette that controls the amount of dialysate passing through the dialyzer, a mixing cassette that forms dialysate from water, and an orienting cassette that routes water from a water supply to the mixing cassette and dialysate from the mixing circuit to the balancing circuit.

[0013] In yet another embodiment, the hemodialysis system includes a cassette system including a directing cassette, a mixing cassette, and a balancing cassette. In some embodiments, the directing cassette can direct water from a water supply to the mixing cassette and dialysate from the mixing cassette to the balancing cassette. The mixing circuit can mix water from the directing cassette with dialysate from a dialysate supply to form a precursor. The balancing cassette can control the amount of dialysate passing through the dialysis machine.

[0014] In one embodiment, the hemodialysis system includes a blood flow path through which blood is pumped from a patient and through the dialyzer, a blood flow path including a blood flow pump, a dialysate flow path through which dialysate flows from a dialysate supply through the dialyzer, the dialysate flow path including a dialysate pump, and a control fluid path through which a control fluid drives the blood flow pump and the dialysate pump.

[0015] In yet another embodiment, the hemodialysis system includes a blood flow path through which blood is pumped from a patient and through the dialyzer, and a dialysate flow path through which dialysate flows from a dialysate supply through the dialyzer. In an embodiment, the dialysate flow path includes at least one pneumatic pump.

[0016] In yet another embodiment, the hemodialysis system includes a first pump having a pump chamber and a drive chamber, a second pump having a pump chamber and a drive chamber, a control fluid communicating with each drive chamber of the first pump and the second pump, and a controller capable of pressurizing the control fluid and controlling the drive of the first pump and the second pump.

[0017] In yet another embodiment, the hemodialysis system includes a first valve having a valve chamber and an actuation chamber, a second valve having a valve chamber and an actuation chamber, a control fluid communicating with each actuation chamber of the first valve and the second valve, and a controller capable of pressurizing the control fluid to control actuation of the first valve and the second valve.

[0018] In one embodiment, the hemodialysis system includes a blood flow path through which blood is pumped from a patient and through a dialyzer, a cassette including at least a portion of the blood flow path, and a spike integrally formed with the cassette, the spike capable of receiving a vial of fluid, the integrally formed spike communicating with the blood flow path within the cassette.

[0019] In another embodiment, the hemodialysis system includes a blood flow path through which blood is pumped from a patient and passed through the dialyzer, a dialysate flow path through which dialysate flows from a dialysate supply and through the dialyzer, and a gas supply in communication with the dialysate flow path such that, when activated, gas from the gas supply causes the dialysate to flow from the dialysate flow path through the dialyzer and return blood in the blood flow path to the patient. The dialyzer causes the dialysate to flow from the dialysate flow path to the blood flow path.

[0020] In yet another embodiment, a hemodialysis system includes a blood flow path into which untreated blood is pumped from a patient and passed through the dialyzer, a dialysate flow path through which dialysate flows from a dialysate supply to the dialyzer, a fluid supply, a chamber in communication with the fluid supply and the dialysate flow path, and a pressurizer for pressurizing the fluid supply to press a septum against the dialysate in the chamber, thereby forcing the dialysate through the dialyzer and blood in the blood flow path back to the patient. The dialyzer causes the dialysate to flow from the dialysate flow path to the blood flow path. The chamber has a septum separating fluid in the fluid supply from the dialysate in the dialysate flow path.

[0021] In yet another embodiment, the hemodialysis system includes a blood flow path in which untreated blood is pumped to a patient and through a dialyzer, a dialysate flow path in which dialysate flows from a dialysate supply through the dialyzer, and a pressurizing device for pushing dialysate in the dialysate flow path to flow into the blood flow path. The dialysate flow path and the blood flow path are in communication.

[0022] In one embodiment, the hemodialysis system includes a first housing containing a positive displacement pump driven by a control fluid, a flow path connecting the positive displacement pump with a control fluid pump, and a second housing containing the control fluid pump, the second housing being detachable from the first housing.

[0023] In another embodiment, the hemodialysis system includes a housing having a first compartment and a second compartment separated by an insulating wall, the first compartment being sterilizable at a temperature of at least about 80° C., and the second compartment including electrical components that do not heat to a temperature of 60° C. or greater when the first compartment is heated to a temperature of at least about 80° C.

[0024] In yet another embodiment, the hemodialysis system includes a blood flow path including at least one blood valve through which untreated blood is pumped from a patient and passes through the dialyzer, a control fluid path for sending a control fluid from a drive mechanism to the blood valve for driving the blood valve, a dialysate mixing system in communication with the dialyzer and including at least one dialysate system valve, and a heater for heating the dialysate. Another aspect of the invention relates to a valve system. In an embodiment, the valve system includes a valve housing including a plurality of valves. At least two of the valves each include a valve chamber and a drive chamber. Each of the at least two valves is driven by a control fluid in the drive chamber. The valve system further includes a control housing having a plurality of fluid interface ports for communicating with the control fluid from a base unit, and a plurality of tubes extending between the valve housing and the control housing. Each tube communicates one of the fluid interface ports with at least one of the drive chambers, such that the base unit can drive the valve by pressurizing the control fluid in the fluid interface port. In an embodiment of the invention, the valve includes a first plate, a second plate, a third plate, and a diaphragm. The second plate has a recess on a side facing the first plate, the recess having a groove formed therein, the groove being open in a direction facing the first plate. The second plate is disposed between the first plate and the third plate. A partition is disposed within the recess between the first plate and the second plate. The partition has an edge, the edge being held within the groove. The second plate includes a valve seat. The partition is pressed by air pressure to seal and close the valve seat. The groove surrounds the valve seat. In an embodiment, a valve inlet and a valve outlet are formed between the second plate and the third plate. In an embodiment, a passageway for creating air pressure is disposed between the first plate and the second plate.

[0025] In a further aspect of the invention, a pump system is disclosed. In an embodiment, the pump system comprises a pump housing including a plurality of pumps. At least two of the pumps each include a pump chamber and an actuation chamber. Each of the at least two pumps is actuable by a control fluid in the actuation chamber. The pump housing comprises a control housing having a plurality of fluid interface ports for communicating with the control fluid from a base unit, and a plurality of tubes extending between the pump housing and the control housing. Each of the tubes communicates between one of the fluid interface ports and at least one of the actuation chambers, such that the base unit can actuate the pumps by pressurizing the control fluid in the fluid interface ports.

[0026] In another aspect of the invention, a pump cassette is disclosed. In an embodiment, the pump cassette comprises at least one fluid inlet, at least one fluid outlet, a fluid passage connecting the at least one fluid inlet and the at least one fluid outlet, and a spike for attaching a vial to the cassette. In an embodiment, the spike is in communication with the fluid passage.

[0027] In one aspect of the invention, a pump cassette for balancing flow to and from a target site is disclosed. In one embodiment, the pump cassette comprises a cassette inlet, a supply line to the target site, a return line from the target site, a cassette outlet, a pump mechanism for directing fluid from the cassette inlet to the supply line and from the return line to the cassette outlet, and a balance chamber. In one embodiment, the pump mechanism comprises a pod pump comprising a rigid curved wall defining a pump volume and having an inlet and an outlet, a diaphragm disposed within the pump volume, and an actuation port connecting the pod pump to a pneumatic actuation system, which actuates the diaphragm to direct fluid into and out of the pump volume. The pump diaphragm separates the fluid from a gas in communication with the pneumatic actuation system. In one embodiment, the balance chamber comprises a rigid curved wall defining a balance volume, and a balance diaphragm disposed within the balance volume. The balance diaphragm separates the balance volume into a supply side and a return side. The supply side and the return side each have an inlet and an outlet. In one embodiment, fluid from the cassette inlet flows to a supply inlet, fluid from the supply outlet flows to a supply line, fluid from the return line flows to a return inlet, and fluid from the return outlet flows to a cassette outlet. In another embodiment, the pump system includes a system inlet, a supply line to the site of interest, a return line from the site of interest, a system outlet, a pump mechanism for moving fluid from the system inlet to the supply line and from the return line to the system outlet, and a balance chamber.

[0028] In an embodiment, the pump mechanism comprises a pod pump comprising a rigid spheroidal wall defining a rigid pump volume and having an inlet and an outlet, a pump diaphragm within the spheroidal wall to the spheroid, and a port connecting the pod pump to a pneumatic actuation system for actuating the diaphragm to move fluid in and out of the pump volume. In an embodiment, the pump diaphragm separates the fluid from a gas in communication with the pneumatic actuation system. In an embodiment, the balance chamber comprises a rigid spheroidal wall defining a balance volume and a balance diaphragm within the spheroidal wall to the spheroid. In an embodiment, the balance diaphragm separates the balance volume into a supply side and a return side, the supply side and the return side each having an inlet and an outlet. In an embodiment, fluid from the system inlet flows to the supply side inlet. Fluid from the supply side outlet flows to the supply line. Fluid from the return line flows to the return side inlet. Fluid from the return side outlet flows to the system outlet. The pump mechanism further comprises a valve mechanism at each of the supply side and return side inlets and outlets. The valve mechanism is pneumatically actuated. A cassette is disclosed in a further aspect of the invention. In an embodiment, the cassette comprises a first flow path connecting the first inlet to the first outlet, a second flow path connecting the second inlet to the second outlet, a pump capable of pumping fluid through at least a portion of the second flow path, and at least two balance chambers. Each balance chamber comprises a rigid container, the rigid container including a partition separating the rigid container into a first compartment and a second compartment. The first compartment of each balance chamber is in communication with the first flow path and the second compartment is in communication with the second flow path.

[0029] In another embodiment, the cassette includes a first flow path connecting the first inlet to the first outlet, a second flow path connecting the second inlet to the second outlet, a control fluid path, at least two pumps, and a balance chamber capable of maintaining flow balance between the first and second flow paths. Each pump comprises a rigid container including a partition separating the rigid container into a first compartment and a second compartment. The first compartment of each pump communicates with the control fluid path and the second compartment communicates with the second flow path. In yet another embodiment, the cassette includes a rigid container including a first flow path connecting the first inlet to the first outlet, a second flow path connecting the second inlet to the second outlet, and a partition separating the rigid container into the first and second compartments. In operation, the first compartment communicates with the first flow path and the second compartment communicates with the second flow path.

[0030] In a further aspect of the invention, a pump is disclosed. In one embodiment, the pump comprises a first rigid element, a second rigid element, and a diaphragm having a rim. The second rigid element has a groove disposed therein on a side facing the first plate. The groove opens in a direction facing the first rigid element. The rim is retained in the groove by a friction fit therein, but the first rigid element does not contact the rim. In one embodiment, the first rigid element and the second rigid element at least partially define a pod pump chamber separated into separate chambers by a diaphragm, and at least partially define a fluid path to the pod pump chamber. The groove surrounds the pod pump chamber. In another embodiment, the pump comprises a generally spherical container including a flexible diaphragm separating the rigid container into a first compartment and a second compartment. The first compartment and the second compartment are not in communication with each other. Movement of the diaphragm by fluid entering the first compartment causes pumping of fluid in the second compartment.

[0031] In another embodiment, the pump is a reciprocating positive displacement pump. In an embodiment, the pump comprises a rigid chamber wall and a flexible diaphragm attached to the rigid chamber wall. The flexible diaphragm and the rigid chamber wall form a pump chamber. The pump further comprises an inlet for distributing flow from the rigid chamber wall to the pump chamber, an outlet for exhausting the pump chamber through the rigid chamber wall, and a restriction wall for restricting movement of the rigid diaphragm and limiting a maximum volume of the pump chamber. The rigid restriction wall forms a drive chamber. The pump further comprises a pneumatic drive system for intermittently applying a control pressure to the drive chamber. In an embodiment, the pneumatic drive system comprises a drive chamber pressure transducer for measuring pressure in the drive chamber, a gas tank having a first pressure, a variable valve mechanism for variably restricting gas flow between the drive chamber and the gas tank, and a controller for receiving pressure information from the drive chamber pressure transducer and controlling the variable valve to thereby create a control pressure in the drive chamber. The control pressure is equal to or less than the first pressure. A further aspect of the invention discloses a method. In an embodiment, the method includes providing a first pump comprising a pump chamber and a drive chamber, and a second pump comprising a pump chamber and a drive chamber, delivering a common fluid to the drive chambers of each of the first pump and the second pump, and pressurizing the common fluid and passing the fluid through each of the first pump and the second pump.

[0032] In another embodiment, the method includes providing a first valve comprising a valve chamber and an actuator chamber, and a second valve comprising a valve chamber and an actuator chamber, delivering a common fluid to each of the actuator chambers of the first valve and the second valve, and pressurizing the common fluid to at least partially pass the fluid through the first valve and the second valve.

[0033] In yet another embodiment, the method is a method for measuring the clearance rate of a dialyzer. The dialyzer is disposed in a blood flow path. Untreated blood is pumped from a patient through the blood flow path and delivered to the dialyzer. Dialysate flows from a dialysate supply through the dialyzer in a dialysate flow path separated from the dialysate flow path by a membrane within the dialyzer. In an embodiment, the method includes passing a liquid through the dialysate flow path through the dialyzer to keep the membrane wet and prevent gas from flowing through the membrane, passing a gas through the blood flow path to the dialyzer to fill the blood flow path within the dialyzer with the gas, measuring the volume of gas within the dialyzer, and calculating the clearance rate based on the volume of gas measured at the dialyzer. In yet another embodiment, the method is a method for measuring the clearance rate of a dialyzer. In an embodiment, the method includes applying an air pressure differential across the dialyzer, measuring a flow rate at the dialyzer, and determining the clearance rate of the dialyzer based on the air pressure differential and the flow rate. In yet another embodiment, the method is a method for measuring the clearance rate of a dialyzer. In one embodiment, the method includes passing water through a dialysis machine, measuring an amount of ions collected by the water after passing through the dialysis machine, and determining a cleaning rate of the dialysis machine based on the amount of ions collected by the water after passing through the dialysis machine. In another embodiment, the method includes passing water through a dialysis machine, measuring a conductivity of the water, and determining a cleaning rate of the dialysis machine based on a change in the conductivity of the water.

[0034] In an embodiment, the method is a method of introducing fluid into blood, in an embodiment, the method includes the steps of providing a cassette including an integrally formed spike for receiving a vial of fluid and a valve mechanism for controlling flow of fluid from the vial to the cassette, attaching a vial containing fluid to the spike, pumping blood through the cassette, and introducing the fluid from the vial into the blood.

[0035] In one embodiment, the method includes providing a hemodialysis system having a blood flow path into which untreated blood is pumped from a patient and through the dialyzer, and a dialysate flow path into which dialysate is passed from a dialysate supply to the dialyzer, communicating the blood flow path with the dialysate flow path, and passing dialysate through the dialysate flow path to deliver blood in the blood flow path to the patient. In another embodiment, the method includes providing a hemodialysis system having a blood flow path into which untreated blood is pumped from a patient and through the dialyzer, and a dialysate flow path into which dialysate is passed from a dialysate supply to the dialyzer, communicating the blood flow path with the dialysate flow path, and passing a gas through the dialysate flow path to flow blood in the blood flow path.

[0036] In yet another embodiment, the method is a method of hemodialysis. In an embodiment, the method includes providing a blood flow path in which untreated blood is pumped from a patient and through the dialyzer, providing a dialysate flow path in which dialysate is passed from a dialysate supply through the dialyzer, providing a feedstock to provide a total volume of dialysate, providing water to mix with the dialysate feedstock, and mixing a volume of water with a portion of the feedstock to provide a first partial volume of dialysate. The first partial volume is small compared to the total volume. The method further includes pumping the partial volume of dialysate through the dialysate flow path and through the dialyzer, and pumping blood through the blood flow path and through the dialyzer. The first partial volume of dialysate is delivered by the pump to the dialyzer. The method further includes mixing a volume of water with a portion of the feedstock to provide a second partial volume of dialysate, and storing the second partial volume of dialysate in a container. The blood and a first partial volume of dialysate are pumped through the dialyzer.

[0037] In another example, a method includes passing blood and dialysate from a patient through a dialyzer included in a hemodialysis system at a first speed and forming dialysate in the hemodialysis system at a second speed different from the first speed, and storing excess dialysate in a container included in the hemodialysis system.

[0038] Another aspect of the invention relates to a hemodialysis system comprising a dialysis unit and a user interface unit. The dialysis unit comprises an automation computer and a dialyzer. The user interface unit comprises a user interface computer and a user interface, the user interface adapted to display information and receive input. The automation computer is configured to receive a request for safety-critical information from the user interface computer and to access the safety-critical information on behalf of the user interface computer. The user interface computer is configured to display information about the dialysis process via the user interface using the safety-critical information.

[0039] Another aspect of the invention relates to a method for managing a user interface in a hemodialysis system, the method including receiving input related to a dialysis process at a user interface associated with a user interface computer, and in response to the input, transmitting a request for safety-critical information from the user interface computer to an automation computer associated with a dialyzer, the method further including accessing the safety-critical information on behalf of the user interface computer, and using the safety-critical information to display information related to the dialysis process via the user interface.

[0040] Yet another aspect of the invention relates to a computer storage medium encoded with instructions that, when executed, perform a method. The method includes receiving input related to a dialysis process from a user interface associated with a user interface computer, and in response to the input, transmitting a request for safety-critical information from the user interface computer to an automation computer associated with the dialysis machine. The method further includes accessing the safety-critical information on behalf of the user interface computer, transmitting the safety-critical information to the user interface computer, accessing screen design information stored within the user interface computer, and using the safety-critical information and the screen design information to cause the user interface to display information related to the dialysis process.

[0041] In another aspect of the invention, a method of forming, for example, one or more hemodialysis systems is disclosed. In a further aspect of the invention, a method of using, for example, one or more hemodialysis systems is disclosed.

[0042] In yet another aspect, the invention relates to a control architecture for the dialysis system, the control architecture comprising a user interface model layer, a therapy layer below the user interface model layer, and a machine layer below the therapy layer. The user interface model layer is configured to manage a state of a graphical user interface and to receive input from the graphical user interface. The therapy layer is configured to execute a state machine that generates therapy commands based at least in part on the input from the graphical user interface. The machine layer is configured to provide commands to actuators based on the therapy commands.

[0043] Another aspect of the invention relates to a method of disinfecting a fluid pathway of a dialysis system, the method including storing disinfection parameters including a disinfection temperature and a disinfection time in at least one storage medium, the method further including circulating a fluid through the fluid pathway, monitoring a temperature of the fluid at each of a plurality of temperature sensors, and determining that disinfection of the fluid pathway is complete when a temperature of the fluid at each of the plurality of temperature sensors remains at or above the disinfection temperature for at least the disinfection time.

[0044] Another aspect of the invention relates to at least one computer readable medium encoded with instructions that, when executed by at least one processing device, perform a disinfection method for disinfecting a fluid pathway of a dialysis system. The method includes electronically receiving disinfection parameters including a disinfection temperature and a disinfection time. The method further includes controlling a plurality of actuators to circulate fluid through the fluid pathway, monitoring a temperature of the fluid at each of a plurality of temperature sensors, and determining whether the temperature of the fluid at each of the plurality of temperature sensors remains at or above the disinfection temperature for at least the disinfection time.

[0045] Another aspect of the invention relates to a method for controlling administration of an anticoagulant in a dialysis system, the method including the steps of storing, in at least one storage medium, an anticoagulant protocol including a maximum amount of anticoagulant, automatically administering anticoagulant according to the anticoagulant protocol, and inhibiting further administration of anticoagulant after determining that the maximum amount of anticoagulant has been administered.

[0046] Another aspect of the invention relates to at least one computer readable medium encoded with instructions that, when executed by at least one processing device, perform a control method for controlling administration of an anticoagulant in a dialysis system, the method including electronically receiving an anticoagulant protocol including a maximum amount of anticoagulant, controlling a plurality of actuators to administer anticoagulant according to the anticoagulant protocol, and inhibiting further administration of anticoagulant after determining that the maximum amount of anticoagulant has been administered.

[0047] Another aspect of the invention relates to a method for determining a fluid level in a dialysate tank of a dialysis system, the method including tracking a first number of strokes that deliver fluid to the dialysate tank, tracking a second number of strokes that drain fluid from the dialysate tank, and determining a fluid level in the dialysate tank based at least in part on the first number of strokes, the second number of strokes, and a volume per stroke.

[0048] Another aspect of the invention relates to a method for determining a fluid level in a dialysate tank of a dialysis system, the method including filling a reference chamber of known volume to a predetermined pressure and venting the reference chamber to the dialysate tank. The method further includes determining the pressure in the dialysate tank after venting the reference chamber to the dialysate tank. Additionally, the method includes determining the fluid level in the dialysate tank based at least in part on the determined pressure in the dialysate tank.

[0049] Another aspect of the invention relates to a method for returning blood to a patient in the event of a power failure condition in a dialysis system that uses compressed air to drive pumps and / or valves during a dialysis process, the dialysis system comprising a dialysis device having a membrane separating a blood flow path from a dialysate flow path. The method includes identifying a power failure condition in the dialysis system. The method further includes, in response to identifying the power failure condition, releasing compressed air from a tank associated with the dialysis system. Additionally, the method includes using the released compressed air to increase pressure in the dialysate flow path, thereby returning blood in the blood flow path to the patient.

[0050] Another aspect of the invention relates to a method for returning extracorporeal blood to a patient in an extracorporeal treatment system in the event of a power failure using a compressed gas source. The extracorporeal treatment system includes a filter having a semi-permeable membrane separating a blood flow path from an electrolyte solution flow path. The compressed gas is in valved communication with an electrolyte solution container, and the electrolyte solution container is in valved communication with the electrolyte solution flow path. The method includes, in response to termination of electrical power to one or more electrically actuated valves that control the distribution of the compressed gas or the distribution of the electrolyte solution flow in the extracorporeal treatment system, causing one or more first electrically actuated valves to open a first fluid path between the compressed gas and the electrolyte solution container, causing one or more second electrically actuated valves to open a second fluid path between the electrolyte solution container and the filter, causing one or more third electrically actuated valves to close an alternative fluid path of the electrolyte solution flow path if the alternative fluid path diverts electrolyte solution from the filter, and returning blood in the blood flow path to the patient by increasing the pressure of the electrolyte solution flow path using compressed gas.

[0051] Another aspect of the invention relates to a method for returning extracorporeal blood to a patient in an extracorporeal treatment system in the event of a power failure, the extracorporeal treatment system comprising a filter having a semi-permeable membrane separating a blood flow path from an electrolyte solution flow path. The compressed gas is in valved communication with an electrolyte solution container, and the electrolyte solution container is in valved communication with the electrolyte solution flow path. The method includes, in response to termination of electrical power to one or more electrically actuated valves that control distribution of the compressed gas or distribution of the electrolyte solution flow in the extracorporeal treatment system, causing the one or more electrically actuated valves to open a fluid path between the compressed gas and the electrolyte solution container, and using the compressed gas to cause a flow of electrolyte solution from the electrolyte solution container to the filter to return blood in the blood flow path to the patient.

[0052] Other advantages and novel features of the present invention will become apparent in the following description of various embodiments of the present invention when considered in conjunction with the accompanying drawings. The embodiments are not limited to those described below. The specification and any references cited herein may include any conflicts or inconsistencies, but the specification shall control. Two or more references cited herein may include any conflicts or inconsistencies with respect to each other, but the later published reference shall control. [Brief description of the drawings]

[0053] [Figure 1] 1 is a schematic diagram showing a hemodialysis system. [Figure 2A] 1 is a high level schematic diagram illustrating various embodiments of a dialysis system. [Figure 2B] 1 is a high level schematic diagram illustrating various embodiments of a dialysis system. [Figure 3A] FIG. 1 is a schematic diagram showing example fluids in a dialysis system. [Figure 3B] FIG. 1 is a schematic diagram showing example fluids in a dialysis system. [Figure 4A] FIG. 1 is a schematic diagram illustrating a blood flow circuit used in one embodiment of a hemodialysis system. [Figure 4B] FIG. 1 is a schematic diagram illustrating a blood flow circuit used in one embodiment of a hemodialysis system. [Figure 4C]FIG. 4B is a perspective view of the air trap of FIG. 4A. [Figure 4D] FIG. 4B is a side view of the air trap of FIG. 4A. [Diagram 5] FIG. 1 is a schematic diagram illustrating a balancing circuit used in one embodiment of a hemodialysis system. [Figure 6] FIG. 1 is a schematic diagram showing a directing circuit for use in a hemodialysis system. [Figure 7A] FIG. 1 is a schematic diagram showing a mixing circuit used in a hemodialysis system. [Figure 7B] FIG. 1 is a schematic diagram showing a mixing circuit used in a hemodialysis system. [Figure 8A] FIG. [Figure 8B] FIG. [Figure 8C] FIG. [Figure 9] 13A-13C are cross-sectional views of valves that may be incorporated into an embodiment of a fluid-control cassette. [Figure 10] 1 is a cross-sectional view of a pod pump that may be incorporated into a fluid-control cassette according to an embodiment. [Figure 11A] Schematic diagrams showing various pneumatic control systems for the pod pump. [Figure 11B] Schematic diagrams showing various pneumatic control systems for the pod pump. [Figure 12] Graph showing how pressure applied to a pod pump is managed. [Figure 13A] FIG. [Figure 13B] FIG. [Figure 14] FIG. 4 is a diagram showing a control algorithm in one embodiment. [Figure 15] FIG. 2 illustrates a standard discrete PI regulator for a controller in one embodiment. [Figure 16] FIG. 1 illustrates a dual housing cassette configuration in one embodiment. [Figure 17A] FIG. 11 is a diagram of priming parts of a system in one embodiment of the invention. [Figure 17B]FIG. 11 is a diagram of priming parts of a system in one embodiment of the invention. [Figure 17C] FIG. 11 is a diagram of priming parts of a system in one embodiment of the invention. [Figure 18A] FIG. 2 illustrates the flow rate of dialysate from the dialysate tank through the dialyzer and out the drain in one embodiment of the invention. [Figure 18B] FIG. 2 illustrates the flow rate of dialysate from the dialysate tank through the dialyzer and out the drain in one embodiment of the invention. [Figure 19] FIG. 13 illustrates emptying of the dialysate tank in another embodiment of the invention. [Figure 20] FIG. 13 illustrates clearing of the system with air at the end of a procedure in one embodiment of the invention. [Figure 21A] FIG. 13 illustrates the air pumping of the anticoagulant pump in another embodiment of the invention. [Figure 21B] FIG. 13 illustrates the air pumping of the anticoagulant pump in another embodiment of the invention. [Figure 21C] FIG. 13 illustrates the air pumping of the anticoagulant pump in another embodiment of the invention. [Figure 22A] FIG. 13 illustrates an integrity test in an embodiment of the invention. [Figure 22B] FIG. 13 illustrates an integrity test in an embodiment of the invention. [Figure 22C] FIG. 13 illustrates an integrity test in an embodiment of the invention. [Figure 22D] FIG. 13 illustrates an integrity test in an embodiment of the invention. [Figure 23] FIG. 13 illustrates a recirculation flow path in another embodiment of the invention. [Figure 24A] FIG. 13 illustrates priming of a system with dialysis fluid in accordance with yet another embodiment of the invention. [Figure 24B] FIG. 13 illustrates priming of a system with dialysis fluid in accordance with yet another embodiment of the invention. [Figure 24C] FIG. 13 illustrates priming of a system with dialysis fluid in accordance with yet another embodiment of the invention. [Figure 24D] FIG. 13 illustrates priming of a system with dialysis fluid in accordance with yet another embodiment of the invention. [Diagram 25] FIG. 13 illustrates priming of an anticoagulant pump in accordance with yet another embodiment of the invention. [Figure 26A] FIG. 13 illustrates the removal of dialysate from the blood flow circuit in one embodiment of the invention. [Figure 26B] FIG. 13 illustrates the removal of dialysate from the blood flow circuit in one embodiment of the invention. [Figure 26C] FIG. 13 illustrates the removal of dialysate from the blood flow circuit in one embodiment of the invention. [Figure 26D] FIG. 13 illustrates the removal of dialysate from the blood flow circuit in one embodiment of the invention. [Figure 26E] FIG. 13 illustrates the removal of dialysate from the blood flow circuit in one embodiment of the invention. [Figure 26F] FIG. 13 illustrates the removal of dialysate from the blood flow circuit in one embodiment of the invention. [Figure 27A] FIG. 13 illustrates the delivery of blood thinner pills to a patient in another embodiment of the invention. [Figure 27B] FIG. 13 illustrates the delivery of blood thinner pills to a patient in another embodiment of the invention. [Figure 27C] FIG. 13 illustrates the delivery of blood thinner pills to a patient in another embodiment of the invention. [Figure 28] FIG. 1 illustrates solution injection in one embodiment of the invention. [Figure 29A] Schematic showing how an emergency cleaning process can be carried out. [Figure 29B] Schematic showing how an emergency cleaning process can be carried out. [Figure 30A] FIG. 13 is an isometric and plan view of an outer top plate of an embodiment of a cassette. [Figure 30B] FIG. 13 is an isometric and plan view of an outer top plate of an embodiment of a cassette. [Figure 30C] FIG. 13 is an isometric and plan view of an embodiment of the inner top plate of the cassette. [Figure 30D] FIG. 13 is an isometric and plan view of an embodiment of the inner top plate of the cassette. [Figure 30E] FIG. 13 is a side view of the top plate of the cassette according to an embodiment. [Figure 31A] 13A and 13B are isometric and top views of the fluid side of an embodiment of a cassette midplate; [Figure 31B] 13A and 13B are isometric and top views of the fluid side of an embodiment of a cassette midplate; [Figure 31C] 13A and 13B are isometric and top views of the air side of the midplate of an embodiment of a cassette; [Figure 31D] 13A and 13B are isometric and top views of the air side of the midplate of an embodiment of a cassette; [Figure 32A] FIG. 13 is an isometric and top view of the inside of the bottom plate of an embodiment of the cassette. [Figure 32B] FIG. 13 is an isometric and top view of the inside of the bottom plate of an embodiment of the cassette. [Figure 32C] FIG. 13 is an isometric and top view of the exterior of the bottom plate of an embodiment of a cassette. [Fig. 32D] FIG. 13 is an isometric and top view of the exterior of the bottom plate of an embodiment of a cassette. [Figure 32E] FIG. 13 is a side view of the bottom plate of the cassette according to an embodiment. [Figure 33A] FIG. 2 is a top view of an assembled cassette with vials attached according to an embodiment. [Figure 33B] FIG. 13 is a bottom view of an assembled cassette with vials attached according to an embodiment. [Figure 33C] FIG. 13 is an exploded view of an assembled cassette with vials attached according to an embodiment. [Figure 33D] FIG. 13 is an exploded view of an assembled cassette with vials attached according to an embodiment. [Figure 34A] FIG. 13 is an isometric bottom view of an embodiment of a cassette midplate; [Figure 34B] FIG. 13 is an isometric top view of an embodiment of a cassette midplate; [Figure 34C] FIG. 13 is an isometric bottom view of an embodiment of a cassette midplate; [Fig. 34D] FIG. 13 is a side view of the midplate of the cassette according to the embodiment; [Figure 35A] FIG. 2 is an isometric and plan view of the top plate of an embodiment of a cassette. [Figure 35B] FIG. 2 is an isometric and plan view of the top plate of an embodiment of a cassette. [Figure 35C] FIG. 2 is an isometric view of the top plate of an embodiment of the cassette. [Figure 35D] FIG. 2 is an isometric view of the top plate of an embodiment of the cassette. [Figure 35E] FIG. 13 is a side view of the top plate of the cassette according to an embodiment. [Figure 36A] FIG. 13 is an isometric bottom view of an embodiment of a bottom plate of a cassette; [Figure 36B] FIG. 13 is an isometric bottom view of an embodiment of a bottom plate of a cassette; [Figure 36C] FIG. 2 is an isometric top view of the bottom plate of an embodiment of the cassette. [Figure 36D] FIG. 2 is an isometric top view of the bottom plate of an embodiment of the cassette. [Figure 36E] FIG. 13 is a side view of the bottom plate of the cassette according to an embodiment. [Figure 37] FIG. 37 is an isometric front view of the drive side of the midplate of a cassette with a valve shown in an embodiment corresponding to FIG. 36 . [Figure 38A] FIG. 13 is a schematic diagram showing an outer top plate of an embodiment of a cassette. [Figure 38B] FIG. 13 is a schematic diagram showing the interior top plate of an embodiment of a cassette. [Figure 38C] FIG. 13 is a side view of the top plate of the cassette according to an embodiment. [Figure 39A] 13 is a schematic diagram of the fluid side of a midplate of an embodiment of a cassette. [Figure 39B] FIG. 13 is a front view of the air side of the midplate of the cassette according to an embodiment; [Figure 39C] FIG. 13 is a side view of the midplate of the cassette according to the embodiment. [Figure 40A] FIG. 13 is a side view of the interior of the bottom plate of the cassette according to an embodiment. [Figure 40B] FIG. 13 is a schematic diagram showing the outside of the bottom plate of the cassette according to an embodiment. [Figure 40C]FIG. 13 is a side view of the midplate of the cassette according to the embodiment. [Figure 41A] 13A and 13B are isometric and front views of the outer top plate of an embodiment of a cassette; [Figure 41B] 13A and 13B are isometric and front views of the outer top plate of an embodiment of a cassette; [Figure 41C] 13A and 13B are isometric and front views of the interior top plate of an embodiment of a cassette. [Figure 41D] 13A and 13B are isometric and front views of the interior top plate of an embodiment of a cassette. [Figure 41E] FIG. 13 is a side view of the top plate of the cassette according to an embodiment. [Figure 42A] 13A and 13B are isometric and front views of the fluid side of the midplate of an embodiment of a cassette. [Figure 42B] 13A and 13B are isometric and front views of the fluid side of the midplate of an embodiment of a cassette. [Figure 42C] 13A and 13B are isometric and front views of the air side of the midplate of an embodiment of the cassette; [Fig.42D] 13A and 13B are isometric and front views of the air side of the midplate of an embodiment of the cassette; [Figure 42E] FIG. 13 is a side view of the midplate of the cassette according to the embodiment. [Figure 43A] 13A and 13B are isometric and front views of the inner side of the bottom plate of the cassette according to an embodiment. [Figure 43B] 13A and 13B are isometric and front views of the inner side of the bottom plate of the cassette according to an embodiment. [Figure 43C] 13A and 13B are isometric and front views of the exterior of the bottom plate of the cassette according to an embodiment. [Fig. 43D] 13A and 13B are isometric and front views of the exterior of the bottom plate of the cassette according to an embodiment. [Figure 43E] FIG. 13 is a side view of the bottom plate of the cassette according to an embodiment. [Figure 44A] FIG. 2 is a plan view showing an assembled cassette in an embodiment. [Figure 44B] FIG. 13 is a bottom view of an assembled cassette according to an embodiment. [Figure 44C] FIG. 13 is an exploded view of an assembled cassette in accordance with an embodiment. [Fig.44D] FIG. 13 is an exploded view of an assembled cassette in accordance with an embodiment. [Diagram 45] FIG. 2 is a cross-sectional view of an assembled cassette system according to an embodiment. [Figure 46A] FIG. 2 is a front view showing an assembled cassette system according to an embodiment. [Figure 46B] FIG. 2 is an isometric view of an assembled cassette system according to an embodiment. [Figure 46C] FIG. 2 is an isometric view of an assembled cassette system according to an embodiment. [Figure 46D] FIG. 2 is an exploded view of an assembled cassette system according to an embodiment. [Figure 46E] FIG. 2 is an exploded view of an assembled cassette system according to an embodiment. [Figure 47A] 1 is an isometric view of a pod of a cassette system according to an embodiment; [Figure 47B] 1 is an isometric view of a pod of a cassette system according to an embodiment; [Figure 47C] FIG. 4 is a side view showing a pod of the cassette system in the embodiment. [Figure 47D] FIG. 2 is an isometric view of half a pod of the cassette system according to an embodiment. [Figure 47E] FIG. 2 is an isometric view of half a pod of the cassette system according to an embodiment. [Figure 48A] FIG. 13 shows an image of a membrane of a pod of a cassette system in an embodiment. [Figure 48B] FIG. 13 shows an image of a membrane of a pod of a cassette system in an embodiment. [Figure 49] FIG. 4 is an exploded view showing a pod of the cassette system according to the embodiment. [Figure 50A] FIG. 13 is an exploded view of the fluid lines of the check valve of the cassette system in one embodiment. [Figure 50B] FIG. 13 is an exploded view of the fluid lines of the check valve of the cassette system in one embodiment. [Figure 50C] 1 is an isometric view of an embodiment of a cassette system showing fluid lines. [Figure 51A] FIG. 2 is a schematic diagram illustrating fluid flow paths of an integrally formed cassette system in one embodiment. [Figure 51B] FIG. 2 is a schematic diagram illustrating fluid flow paths of an integrally formed cassette system in one embodiment. [Figure 52A] 1A-1D are various schematic diagrams illustrating blocks for connecting pneumatic tubes to a manifold in a system according to one embodiment of the present invention. [Figure 52B] 1A-1D are various schematic diagrams illustrating blocks for connecting pneumatic tubes to a manifold in a system according to one embodiment of the present invention. [Figure 52C] 1A-1D are various schematic diagrams illustrating blocks for connecting pneumatic tubes to a manifold in a system according to one embodiment of the present invention. [Fig. 52D] 1A-1D are various schematic diagrams illustrating blocks for connecting pneumatic tubes to a manifold in a system according to one embodiment of the present invention. [Figure 52E] 1A-1D are various schematic diagrams illustrating blocks for connecting pneumatic tubes to a manifold in a system according to one embodiment of the present invention. [Fig. 52F] 1A-1D are various schematic diagrams illustrating blocks for connecting pneumatic tubes to a manifold in a system according to one embodiment of the present invention. [Figure 53] FIG. 11 is a schematic diagram showing a sensor manifold according to another embodiment. [Figure 54] FIG. 54 is a diagram showing flow paths within the sensor manifold shown in FIG. 53. [Figure 55] FIG. 54 is a side view of the sensor manifold shown in FIG. 53. [Figure 56A] 56B is a cross-sectional view of the sensor manifold shown in FIG. 53 taken along line AA in FIG. 56B. [Figure 56B] FIG. 54 is a front view showing the sensor manifold shown in FIG. 53. [Figure 57] FIG. 54 is an exploded view of the sensor manifold shown in FIG. 53. [Figure 58]FIG. 54 illustrates an edge connector for the printed circuit board and media corresponding to the sensor manifold shown in FIG. 53. [Figure 59] Fluid design diagram of a hemodialysis system. [Figure 60] FIG. 1 is a perspective view showing a combination of a user interface and a treatment device according to an embodiment. [Figure 61] 61 is a schematic diagram showing the hardware configuration of the display unit and the user interface unit shown in FIG. 60. [Figure 62] FIG. 62 is a schematic diagram illustrating software processes that may be executed on the automation computer and user interface computer shown in FIG. 61 . [Figure 63] Schematic diagram showing the flow of information between the hardware and software components of the user interface computer and the automation computer. [Figure 64] 64 is a schematic diagram illustrating a hierarchical state machine (HSM) that may be used in the UI controller shown in FIG. 63. [Figure 65] 62A-62C are schematic diagrams illustrating normal and alarm screen displays that may be displayed on the user interface shown in FIG. 61 . [Figure 66] Schematic diagram showing how the Therapy Layer interfaces with other layers such as the Machine Layer and the User Interface Model Layer. [Figure 67] Schematic diagram showing an example implementation of the machine layer shown in Figure 66. [Figure 68] Schematic diagram showing an example implementation of a recycling preparation application. [Figure 69A] Schematic diagram showing an example implementation of a Blood Pathway Cleaning application. [Figure 69B] Schematic diagram showing an example implementation of a Blood Pathway Cleaning application. [Figure 70A] Schematic diagram showing an example implementation of a disinfection application. [Figure 70B] Schematic diagram showing an example implementation of a disinfection application. [Figure 71] Schematic showing an example implementation of an endotoxin cleanup application. [Figure 72] FIG. 1 is a schematic diagram illustrating an example implementation of a treatment preparation application. [Figure 73A] Schematic diagram showing an example implementation of the Patient Connect application. [Figure 73B] Schematic diagram showing an example implementation of the Patient Connect application. [Figure 73C] Schematic diagram showing an example implementation of the Patient Connect application. [Fig. 73D] Schematic diagram showing an example implementation of the Patient Connect application. [Fig. 74A] Schematic diagram showing an example implementation of a dialysis application. [Fig. 74B] Schematic diagram showing an example implementation of a dialysis application. [Fig. 75A] Schematic showing an example implementation of a solvent injection application. [Fig. 75B] Schematic showing an example implementation of a solvent injection application. [Fig. 75C] Schematic showing an example implementation of a solvent injection application. [Fig. 75D] Schematic showing an example implementation of a solvent injection application. [Fig. 75E] Schematic showing an example implementation of a solvent injection application. [Figure 76A] FIG. 1 is a schematic diagram showing an example implementation of a rinseback application. [Figure 76B] FIG. 1 is a schematic diagram showing an example implementation of a rinseback application. [Figure 77] Schematic diagram showing an example implementation of a sampling application. [Fig. 78A] FIG. 1 is a schematic diagram showing an implementation example of a part replacement application. [Fig. 78B] FIG. 1 is a schematic diagram showing an implementation example of a part replacement application. [Fig. 78C] FIG. 1 is a schematic diagram showing an implementation example of a part replacement application. [Figure 79A] Schematic diagram showing an example implementation of a chemical mounting application. [Figure 79B] Schematic diagram showing an example implementation of a chemical mounting application. [Figure 80]FIG. 2 is a diagram showing the pathway between the pressurized air tank and the dialysate tank in a hemodialysis system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0054] Non-limiting embodiments of the present invention are disclosed with reference to the accompanying drawings, which are not intended to be drawn to scale. Identical or nearly identical elements in the drawings are typically each designated by a single reference numeral. For clarity, not every element is designated by a reference numeral in every drawing, and not every element of each embodiment of the present invention is shown to allow one skilled in the art to understand the present invention.

[0055] The present invention relates to hemodialysis systems and similar dialysis systems, including various systems and methods that can make hemodialysis more efficient, easier, and / or less expensive. In an embodiment of the invention, a novel fluid circuit for fluid flow is shown. In an embodiment, the hemodialysis system includes a blood flow path and a dialysate flow path, the dialysate flow path including one or more balancing, mixing, and / or directing circuits. In an embodiment, the pretreatment of the dialysate by the mixing circuit is separate from the dialysis of the patient. In an embodiment, the circuit is at least partially provided within one or more cassettes, and optionally interconnected with conduits, pumps, etc. In an embodiment, the fluid circuit and / or the various fluid flow paths are at least partially, spatially, and / or thermally isolated from the electrical components of the hemodialysis system. In an embodiment, a gas supply is provided in communication with the dialysate flow path and / or the dialyzer. When activated, the gas supply can encourage the dialysate to pass through the dialyzer and the blood in the blood flow path to return to the patient's body. The above system is useful, for example, in emergency situations (e.g., power outages) where it is desirable to return as much blood as possible to the patient. In another aspect of the invention, the hemodialysis system further includes one or more fluid treatment devices, such as pumps, valves, mixers, etc., that can be actuated using a control fluid, such as air. In some embodiments, the control fluid is delivered to the fluid treatment devices using a removable external pump or other device. In some embodiments, the one or more fluid treatment devices are generally rigid (e.g., have a spherical shape), and optionally include a partition within the device that separates the device into a first and second compartment.

[0056] Various aspects of the present invention are directed to novel hemodialysis systems, such as hemofiltration systems, hemodiafiltration systems, plasma exchange systems, etc. Although various systems and methods are disclosed that relate to hemodialysis, the various systems and methods may be applicable to other dialysate systems and / or extracorporeal systems capable of treating other bodily fluids, such as blood or plasma.

[0057] As described above, a hemodialysis system typically includes a blood flow path and a dialysate flow path. It should be noted that the flow of fluid in the flow path is not necessarily linear, but rather there may be any number of "branches" in the flow path where the fluid flows from the inlet of the flow path to the outlet of the flow path. Examples of such branches are described in detail below. In the blood flow path, blood is pumped from the patient and passes through the dialyzer before being returned to the patient. The blood is processed by the dialyzer, and waste molecules (e.g., urea, creatinine, etc.) and water pass from the blood through the dialyzer and into the dialysate. The dialysate passes through the dialyzer through the dialysate flow path. In various embodiments, blood is pumped from the patient through two lines (e.g., an arterial line and a venous line, i.e., "two needle" flow), or in some cases, blood is pumped from the patient and returned to the patient through the same needle (e.g., both lines are provided in the same needle, i.e., "one needle" flow). In yet another embodiment, a "Y" or "T" branch is used. Here, blood is pumped from and returned to the patient through a patient connection that has two branches, one for pumping blood and one for returning blood. The patient may be any subject requiring hemodialysis or a similar treatment, but the patient is usually a human. However, hemodialysis may also be performed on non-human subjects, such as dogs, cats, monkeys, etc.

[0058] Fresh dialysate is prepared in the dialysate flow path and passed through the dialyzer to treat blood from the blood flow path. The dialysate is further equilibrated (i.e., pressure between the dialysate and blood is equilibrated) in the dialyzer for treatment of the blood, i.e., the pressure of the dialysate passing through the dialyzer closely matches, usually exactly, the blood pressure passing through the dialyzer, or in some embodiments, within at least about 1% or about 2% of the blood pressure. After passing through the dialyzer, the used dialysate contains waste molecules (described below). In some embodiments, the dialysate is heated using a suitable heater, such as an electrical resistance heater, prior to treatment of the blood in the dialyzer. The dialysate is further filtered, for example, using an ultrafilter to remove contaminants, infectious organisms, and debris. The ultrafilter has a mesh size selected to prevent the above types from passing through. For example, the mesh size may be about 0.3 micrometers or less, about 0.2 micrometers or less, about 0.1 micrometers or less, or about 0.05 micrometers or less, etc. Dialysates are used to draw waste molecules (e.g., urea, creatinine, ions such as potassium, phosphate, etc.) and water from the blood into the dialysate through osmosis. Dialysates are well known to those skilled in the art.

[0059] Dialysate typically contains various ions, such as potassium and calcium, that are similar to the natural concentrations found in healthy blood. In some embodiments, the dialysate contains sodium bicarbonate, typically at a higher concentration than that found in normal blood. Dialysate typically contains one or more ingredients, namely, "acid" (including various types such as acetic acid, glucose, NaCl, CaCl, KCl, MgCl, etc.), sodium bicarbonate (NaHCO 3 Dialysis fluid is prepared by mixing sodium phosphate phosphate (SAP) and / or sodium chloride (NaCl) with water from a water supply. Preparation of dialysis fluid, including using appropriate concentrations of salts, osmolality, pH, etc., is well known to those of skill in the art. As described in more detail below, the dialysis fluid need not be prepared to the same concentration at which it will be used to treat blood. For example, the dialysis fluid can be formed simultaneously with or prior to dialysis and contained within a dialysis fluid storage container or the like.

[0060] In a dialysis machine, the dialysate and blood do not usually come into physical contact with each other, but are separated by a semipermeable membrane. Typically, the semipermeable membrane is made of a polymer such as cellulose, polyarylethersulfone, polyamide, polyvinylpyrrolidone, polycarbonate, polyacrylonitrile, etc., which allows ions and small molecules (e.g., urea, water, etc.) to pass through the membrane, but does not allow bulk particles to pass through or convect into the blood during treatment. In some instances, larger particles such as beta-2 microglobulin also pass through the membrane.

[0061] The dialysate and blood do not physically contact each other within the dialysis machine, but are usually separated by a semi-permeable membrane. Dialysis machines are typically constructed with a "shell-and-tube" design consisting of multiple separate tubes or fibers formed from semi-permeable membranes through which the blood flows, and a larger "shell" (or in some embodiments, the reverse) through which the dialysate flows and which surrounds the tubes or fibers. In some embodiments, the flow of dialysate and blood through the dialysis machine may be countercurrent or cocurrent. Dialysis machines are well known to those skilled in the art and are available from many different commercial sources.

[0062] In one embodiment, the dialysate flow path is separated into one or more circuits, i.e., a balancing circuit, a mixing circuit, and / or a directing circuit. With respect to fluid flow, it should be noted that a circuit does not necessarily have to be fluid-separated, and fluids may flow into and out of a fluid circuit. Similarly, fluids may flow from one fluid circuit to another, when the fluid circuits are in communication or are interconnected in communication. As used herein, "fluid" refers to a fluid that has characteristics of a fluid, including, but not limited to, gases such as air, liquids such as water, aqueous solutions, blood, dialysate, and the like.

[0063] A fluid circuit is typically a distinct module that accepts any number of fluid inputs and, in some embodiments, performs one or more tasks in response to the fluid inputs before providing a suitable output of the fluid. As described below in some embodiments of the present invention, the fluid circuit is formed as a cassette. In some embodiments, the dialysate flow path includes a balancing circuit, a directing circuit, and a mixing circuit. In other embodiments, the blood flow path includes a blood flow circuit. In the balancing circuit, the dialysate is guided into the balancing circuit, and the pump acts on the dialysate such that the pressure of the dialysate passing through the dialyzer balances the pressure of the blood passing through the dialysate, as described above. Similarly, in the directing circuit, fresh dialysate moves from the mixing circuit to the balancing circuit, and used dialysate moves from the balancing circuit to a drain. In the mixing circuit, the material and water mix to form fresh dialysate. The blood flow circuit is used to pump blood from the patient, pass blood through the dialyzer, and return blood to the patient. These circuits are described in more detail below.

[0064] FIG. 2A is a high-level schematic diagram of an example of a hemodialysis system having the above-described fluid circuits. FIG. 2A shows a dialysis system 5 with a blood flow circuit 10 through which blood moves from a patient to a dialyzer 14 and through which treated blood passes back to the patient. The hemodialysis system in this example further includes a balancing circuit or inner dialysate circuit 143, which pumps dialysate after the dialysate has passed through the ultrafilter 73 and through the dialyzer 14. The used dialysate returns from the dialyzer 14 to the balancing circuit 143. The directing circuit or outer dialysate circuit 142 processes the unused dialysate before it passes through the ultrafilter 73. The mixing circuit 25 prepares dialysate using various ingredients 49 and water during and / or prior to dialysis, e.g., on demand. The directing circuit 142 also receives water from the water supply 30 and moves the water to the mixing circuit 25 for preparation of dialysate. Directing circuit 142 also receives spent dialysate from balancing circuit 143 and transfers it out of system 5 through drain 31. Additionally, a conduit 67 is shown in dashed lines connecting between blood flow circuit 10 and directing circuit 142 for sterilization of the hemodialysis system. In an embodiment, one or more of these circuits (e.g., blood flow circuit, balancing circuit, directing circuit, and / or mixing circuit) include cassettes containing the valves and pumps required to control flow through the segments. Examples of such systems are described in more detail below.

[0065] FIG. 2B is a schematic diagram of a hemodialysis system according to an embodiment of the present invention. In this diagram, a blood flow cassette 22 is used to control the flow through the blood flow circuit 10, and a dialysate cassette 21 is used to control the flow through the dialysate circuit. The blood flow cassette includes at least one inlet valve 24 (alternatively, one or more inlet valves) to control the flow of blood through the cassette 22. Additionally, an anticoagulant valve or pump 12 controls the flow of anticoagulant into the blood, and in an embodiment, the blood flow pump 13 includes a pair of pod pumps. These pod pumps may be of the type disclosed in U.S. Patent Application Serial No. 60 / 792,073, filed August 14, 2006, and entitled "Extracorporeal Thermal Therapy System and Method," or of the type disclosed in U.S. Patent Application Serial No. 11 / 787,212, filed August 13, 2007, and entitled "Fluid Pumping System, Apparatus, and Method" (or variations of these types). All of the pumps and valves in this example system can be controlled by a control system, such as an electronic digital control system, although other control systems are possible in alternative embodiments.

[0066] Providing two pod pumps allows blood to flow continuously through the blood flow circuit 10, although a single pod pump could alternatively be used. The pod pump may include dynamic inlet and outlet valves (instead of static check valves at the inlet and outlet) that allow flow in the blood flow circuit 10 to be reversed under certain circumstances. For example, reversing the flow in the blood flow circuit allows the hemodialysis system to ensure that the outlet of the blood flow circuit is properly connected to the patient and that treated blood is being properly returned to the patient. For example, if the patient connection point becomes disconnected, such as by being dropped, reversing the blood flow pump will draw in air rather than blood. This air is detected by a standard air detector built into the system.

[0067] In another embodiment, the blood outlet valve 26 and air trap or filter 19, located downstream of the dialysis machine, are incorporated within the blood flow cassette 22. The pod pump and all valves within the blood flow cassette 22, including the valves associated with the inlet and outlet of the pod pump, are pneumatically actuated. In one embodiment, the source of positive and negative gas pressure is provided by a base unit that holds the cassette or by another device that holds the cassette. However, in another embodiment, the source of positive and negative gas pressure may be provided by an external device that is fluidly coupled to the cassette or by a device that is incorporated within the system. The pump chamber is actuated as disclosed in U.S. patent application Ser. No. 60 / 792,073, filed Aug. 14, 2006, and entitled "Extracorporeal Thermal Therapy System and Method," and U.S. patent application Ser. No. 11 / 787,212, filed Aug. 13, 2007, and entitled "Fluid Pumping System, Device, and Method." For example, the pump is controlled and end of stroke is detected as described below. The blood flow cassette 22 further includes an integrally formed spike for receiving a vial of anticoagulant.

[0068] In one embodiment, the anticoagulant pump comprises three fluid valves (controlled by a control fluid) and a pump compartment (alternatively, more than one pump compartment may be provided). The valves connect the compartments to a filtered vent, to a vial of anticoagulant (or other source of anticoagulant, such as a bag or vial), or to the blood flow path. The anticoagulant pump may be actuated by sequentially opening and closing the fluid valves, for example by controlling the pressure in the pump compartment with the control fluid. As anticoagulant is removed from the vial, it is replaced by an equal volume of air, for example to keep the pressure in the vial relatively constant. Substituting air for anticoagulant as described above may be accomplished, for example, by (i) opening a valve from a filtered vent to the pump compartment, (ii) forcing air into the compartment by connecting a negative pressure source to the chamber, (iii) closing the vent valve, (iv) opening a valve connecting the compartment to the vial, and (v) forcing air into the vial by connecting a positive pressure source to the compartment. Anticoagulant is pumped from the vial to the blood flow path by a similar sequence using valves to the vial and blood flow path rather than to the vent and vial.

[0069] FIGURE 3A is a schematic diagram of an embodiment of the embodiment shown in FIGURE 2A. FIGURE 3A details how blood flow circuit 141, balancing circuit 143, directing circuit 142, and mixing circuit 25 are provided in a cassette and related to each other and to dialyzer 14, ultrafilter 73, and / or heater 72 in an embodiment of the invention. FIGURE 3A shows only one possible hemodialysis system for the embodiment of FIGURE 2A, although other fluid circuits, modules, flow paths, layouts, etc. are possible in alternative embodiments. Examples of such systems are described in more detail below. Further, these applications include U.S. Patent Application No. 60 / 903,582, filed February 27, 2007, entitled "Hemodialysis System and Method," U.S. Patent Application No. 60 / 904,024, filed February 27, 2007, entitled "Hemodialysis System and Method," U.S. Patent Application No. 11 / 871,680, filed October 12, 2007, entitled "Pump Cassette ... No. 11 / 871,712, filed Oct. 12, 2007 and entitled "Pump Cassette," U.S. patent application Ser. No. 11 / 871,787, filed Oct. 12, 2007 and entitled "Pump Cassette," U.S. patent application Ser. No. 11 / 871,793, filed Oct. 12, 2007 and entitled "Cassette System Integrated Apparatus," and U.S. patent application Ser. No. 11 / 871,803, filed Oct. 12, 2007 and entitled "Cassette System Integrated Apparatus," each of which is incorporated herein by reference in its entirety.

[0070] The elements shown in FIG. 3A are described below. Briefly, the blood flow circuit 141 includes an anticoagulant supply 11 and a blood flow pump 13 that pumps blood from the patient to the dialyzer 14. The illustrated anticoagulant supply 11 is located in the blood flow path to the dialyzer, but in other embodiments it may be located in the blood flow path to the patient or in another suitable location. The anticoagulant supply 11 is located downstream of the blood flow pump 13. The balancing circuit 143 includes two similar pumps, a dialysate pump 15 that pumps dialysate to the dialyzer 14, and a bypass pump 35. The directing circuit 142 includes a dialysate pump 159 that pumps dialysate from a dialysate tank 169 through a heater 72 and / or an ultrafilter 73 to the balancing circuit. The directing circuit 142 pumps waste from the balancing circuit 143 to a drain 31.

[0071] In one embodiment, blood flow circuit 141 is connected to directing circuit 142 via conduit 67 for, e.g., sterilization, as described below. Dialysate flows from a dialysate supply to a dialysate tank 169. In one embodiment, as shown in FIG. 3A, dialysate is formed in mixing circuit 25. Water from water supply 30 flows into mixing circuit 25 through directing circuit 142. Dialysate ingredients 49 (e.g., bicarbonate and acid) are further added into mixing circuit 25, and a series of mixing pumps 180, 183, 184 are used to form the dialysate. The dialysate is then delivered to directing circuit 142.

[0072] One of the fluid circuits in this example system is the blood flow circuit, blood flow circuit 141 shown in FIG. 3A. In the blood flow circuit, blood from the patient is pumped through the dialyzer and returned to the patient. As will be described below, in an embodiment the blood flow circuit is provided in a cassette, but this need not be the case. In an embodiment, the flow of blood through the blood flow circuit is balanced with the flow of dialysate through the dialysate flow path, particularly through the dialyzer and the balancing circuit.

[0073] An example of a blood flow circuit is shown in FIG. 4. Typically, blood flows from the patient through an arterial line 203, through a blood flow pump 13, and to a dialysis machine 14 (the flow direction in typical dialysis is shown by arrow 205; however, in other modes of operation, the flow is in another direction). Optionally, an anticoagulant is introduced into the blood from an anticoagulant supply via an anticoagulant pump 80. As shown in FIG. 4, the anticoagulant enters the blood flow path after the blood has passed through the blood flow pump 13. However, in other embodiments, the anticoagulant is added at any suitable location along the blood flow path. In other embodiments, an anticoagulant supply 11 is provided at a location downstream of the blood flow pump. After passing through the dialysis machine 14 and undergoing dialysis, the blood returns to the patient through a venous line 204, and optionally through an air trap or a blood sample port 19.

[0074] As shown in FIG. 4, the blood flow cassette 141 further includes one or more blood flow pumps 13 for moving blood through the blood flow cassette. The pumps may be, for example, pumps driven by a control fluid, as described below. In one embodiment, for example, the pumps 13 include two (or more) pod pumps, i.e., pod pumps 23, as shown in FIG. 4. In this embodiment, each pod pump includes a rigid chamber with a flexible diaphragm or membrane separating each chamber into a fluid compartment and a control compartment. The compartments are provided with four inlet or outlet valves, two in the fluid compartments and two in the control compartment. The valves in the control compartments of the chambers are bidirectional proportional valves, one connected to a first source of control fluid (e.g., a high pressure air source) and the other connected to a second source of control fluid (e.g., a low pressure air source) or a vacuum sink. The fluid valves in the compartments are openable and closable to allow fluid flow when the pod pump is activated. Examples of these pod pumps are disclosed, but are not limited to, in U.S. patent application Ser. No. 60 / 792,073, filed Aug. 14, 2006, and entitled "Extracorporeal Thermal Therapy System and Method," and U.S. patent application Ser. No. 11 / 787,212, filed Aug. 13, 2007, and entitled "Fluid Pumping System, Apparatus, and Method," both of which are incorporated herein in their entireties. Further details of pod pumps are provided below. When more than one pod pump is provided, the pod pumps can be operated in any suitable manner, for example, synchronously or asynchronously, in phase or out of phase.

[0075] In this embodiment, for example, the two pumps may be rotated out of phase to affect the pumping period, i.e., one pump chamber is filled and the second pump chamber is emptied. The phase relationship between 0° (pod pumps drive in the same direction) and 180° (pod pumps drive in opposite directions) can be selected to obtain the desired pumping period.

[0076] A 180° phase relationship results in continuous flow into and out of the pod pump. For example, this is preferred when continuous flow is desired, i.e., for dual needle flow or use with a "Y" or "T" junction. However, a 0° phase relationship may be useful in one needle flow or other embodiments. In a 0° relationship, the pod pump fills first from the needle and uses the same needle to return blood to the patient through the blood flow path. Additionally, in embodiments, actuation between 0° and 180° may be used to achieve a push-pull relationship (hemodiafiltration or continuous backflow) across the dialysis machine. Figures 8A-8C are diagrams showing examples of such phase relationships. In these figures, the volume or flow of each pod pump, the volume of each pod pump, and the total volume of both pod pumps are plotted against the time axis. These times and fluid rates are arbitrarily selected and shown to illustrate the relationship between the pod pumps at different phases. For example, in a 180° phase relationship as shown in Figure 8B, the total volume is approximately constant.

[0077] In one embodiment, as shown in FIG. 4, an anticoagulant (e.g., heparin or other anticoagulant known to one of skill in the art) is mixed with the blood in blood flow cassette 141. For example, the anticoagulant may be contained in vial 11 (or other anticoagulant supply such as tubing or bag), and blood flow cassette 141 may receive the vial of anticoagulant with an integrally formed spike 201 (which in one embodiment is a needle) capable of piercing the seal of the vial. The spike may be formed of plastic, stainless steel, or other suitable material, and in one embodiment is a sterilizable material. For example, the material may be sufficiently resistant to high temperatures and radiation to sterilize the material. In one embodiment, as shown in FIG. 4, spike 201 may be integrally formed with blood flow cassette 141, vial 11 may be positioned on the spike, and the spike may pierce the seal of the vial. This allows the anticoagulant to mix with the blood in the blood flow path and possibly flow into the blood flow cassette to be mixed with the dialysate, as described below.

[0078] In some embodiments, a third pump 80 of the blood flow cassette 141, which functions as a metering chamber, can be used to control the flow of anticoagulant to the blood in the cassette. The third pump 80 can be the same design as pump 13 or a different design. For example, the third pump 80 can be a pod pump and / or the third pump 80 can be driven by a control fluid such as air. For example, as shown in FIG. 4, the third pump 80 includes a rigid chamber with a flexible partition separating the chamber into a fluid compartment and a control compartment. A valve in the control compartment of the chamber is connected to a first control fluid source (e.g., a high pressure air source) and the other compartment is connected to a second control fluid source (e.g., a low pressure air source) or a vacuum sink. The valve in the fluid compartment of the chamber is opened or closed in response to the control compartment, thereby controlling the flow of anticoagulant to the blood. Further details of the pod pump are provided below. Air is directed into the blood flow path through a filter 81, as described below in some embodiments.

[0079] Fluid management system (FMS) measurements are used to measure the volume of fluid pumped through the pump chamber during a membrane stroke or to detect air in the pump chamber. Fluid management system methods are described in U.S. Patent Nos. 4,808,161, 4,826,482, 4,976,162, 5,088,515, and 5,350,357, which are incorporated by reference in their entireties. In some examples, the volume of fluid delivered by an anticoagulant pump, dialysate pump, or other membrane-based pump is determined using a fluid management system algorithm that uses the pressure change in the chamber to calculate volume measurements at the end of the fill stroke and the end of the deliver stroke. The difference between the calculated volumes at the end of the fill stroke and the end of the deliver stroke is the actual stroke volume. This actual stroke volume can be compared to an expected stroke volume for a chamber of a given size. If the actual volume and the expected volume differ significantly, the stroke is not properly completed and an error message is generated.

[0080] When stroke volumes are collected by the scale, calculations are performed in the background to determine a calibration value for the reference chamber. The FMS vents to atmosphere for the FMS measurement. Alternatively, the system may vent to a high pressure positive source and a low pressure negative source for the FMS measurement. This provides the following advantages: (1) if the high pressure source is a pressure tank with a controlled pressure, there is an opportunity to cross-check the tank and chamber pressure sensors to ensure they are similar when the chamber is open to the tank. These can be used to detect pressure sensor failures or valve failures. (2) Using higher or lower pressures for venting will give a better answer since a larger pressure difference will be created for the FMS measurement.

[0081] Blood flow circuit 141, in one embodiment, includes an air trap 19 that is incorporated into blood flow circuit 141. Air trap 19 is used to remove air bubbles within the blood flow path. In one embodiment, air trap 19 can separate air that is generated from the blood by gravity. In one embodiment, air trap 19 further includes a port for blood sampling. Air traps are well known to those of skill in the art.

[0082] According to another aspect of the invention, an air trap 19 is provided in the blood flow path after the blood leaves the dialysis machine and before it returns to the patient. As shown in Figures 4C and 4D, the air trap 19 has a spherical or spheroidal container 6 with an inlet port 7 near the top of the container, offset from its vertical axis, and an outlet 9 at the bottom of the container. The curved shape of the trap's inner wall 4 thus guides the blood to circulate along the inner wall as it descends to the bottom of the container under the effect of gravity, helping to remove air bubbles from the blood. Air present in the blood exiting the outlet 9 of the dialysis machine 14 enters the top of the air trap 19 and remains at the top of the container as the blood leaves the bottom outlet and enters the venous blood line 204. By providing the inlet port 7 near the top of the trap 19, it is also possible to circulate blood through a trap with little or no air in the container (as a "run-full" air trap). It is advantageous to eliminate the air-blood interface for normal blood circulation in the trap. Providing the inlet port 7 at or near the top of the vessel also allows most or all of the air present in the trap to be removed from the trap by reversing the flow of fluid through the blood tube (i.e., from the bottom to the top of the trap 19, and venting through the inlet port of the trap 19). In an embodiment, a self-sealing port 3, such as a self-sealing stopper with a split septum or membrane, or another configuration, is provided at the top of the trap, allowing air to be vented from the vessel (e.g., by a syringe). The blood-facing surface of the self-sealing membrane can be positioned approximately flush with the top of the trap interior to facilitate cleaning of the self-sealing port during disinfection. The self-sealing port 3 can also function as a blood sampling site and / or to allow introduction of liquids, drugs, or other compounds into the blood circuit. If needle access is envisioned, a sealing rubber type stopper can be used. Using a self-sealing stopper with a split septum allows for sampling and fluid transfer using a needleless system.

[0083] Additional fluid connections 82 also allow blood flow circuit 10 to be connected to a patient and / or to a fluid source for priming or sterilizing a system including blood flow circuit 10. Typically, during sterilization, arterial line 203 and venous line 204 are directly connected to directing circuit 142 via conduit 67, which allows the fluid to be sterilized (e.g., hot water or a combination of hot water and one or more chemicals in one embodiment) to be returned to directing circuit 142 for recirculation through dialysis machine 14 and blood flow circuit 141. This sterilization is similar to that disclosed in U.S. Patent No. 5,651,898 to Kenley et al., which is incorporated herein in its entirety, and which is further described below.

[0084] The pressure in the arterial line 203 is maintained at subatmospheric pressure in an embodiment to pump blood from the patient. When a pod pump is used, the pressure in the blood flow pump 13 is inherently limited to the pressure available from the positive and negative pressure tanks used to power the pump. In the event of a pressure tank or valve failure, the pressure in the pump chamber approaches the tank pressure. This causes fluid pressure to rise to match the tank pressure up to the diaphragm in the "bottom" of the pod pump (i.e., it is in contact with a surface and cannot move). The fluid pressure does not exceed safe limits and balances with natural body fluid pressure. This failure will cause the pod pump to stop working naturally without any special intervention.

[0085] A non-limiting example of a blood flow cassette is shown in Figures 30-33. Figures 30A and 30B show the outside of the top plate 900 of an embodiment of the cassette. The top plate 900 contains one half of the pod pumps 820, 828. This half is the fluid half through which the source fluid flows. Two fluid paths 818, 812 are shown. These paths are directed to the respective pod pumps 820, 828.

[0086] The pod pump 820, 828 includes elevated flow paths 908, 910. The elevated flow paths 908, 910 allow fluid to continue to flow through the pod pump 820, 828 after a bulkhead (not shown) reaches the end of a stroke. The elevated flow paths 908, 910 therefore minimize bulkheads that could cause the pod pump 820, 828 to trap air or fluid or block the inlet or outlet of the pod pump 820, 828 preventing continuous flow. The elevated flow paths 908, 910 have a predetermined size in one embodiment, and in some embodiments, the size is comparable to the fluid paths 818, 812. However, in other embodiments, the elevated flow paths 908, 910 are narrower, and in still other embodiments, the elevated flow paths 908, 910 can be any size since the purpose is to control the fluid to obtain a desired flow rate or flow rate of the fluid. In some embodiments, the elevated fluid paths 908, 910 and fluid paths 818, 812 may be different sizes. Thus, the dimensions shown for the elevated fluid paths, pod pumps, valves, and other aspects are exemplary and illustrative only. Other embodiments are apparent.

[0087] In one embodiment of this cassette, the top plate includes a spike 902 as well as a pedestal 904 for the container. The spike 902 is empty in this example and is fluidly connected to the flow path. In an embodiment, a needle is attached to the spike. In another embodiment, the needle is connected to a fitting for the container.

[0088] 30C and 30D show the interior of the top plate 900. The elevated channels 908, 910 connect to the inlet channels 912, 916 and outlet channels 914, 918 of the pod pumps 820, 828. The elevated channels are described in detail above.

[0089] The metering pump (not shown) includes a connection to the airway 902 of the spike as well as a connection to the vent 906. In one embodiment, the vent 906 includes an air filter (not shown). The air filter is a particulate air filter in one embodiment. In one embodiment, the filter is a somicron hydrophobic air filter. In various embodiments, the size of the filter varies and depends on the results desired. The metering pump is powered by taking in air through the vent 906, pumping the air through the airway 902 of the spike into a container of a second fluid (not shown), and then pumping a volume of the second fluid from the container (not shown) through the airway 902 of the spike into the fluid line at point 826. This fluid path for the metering pump is shown by the arrows in FIG. 30C.

[0090] 31A and 31B show the fluid side of the midplate 1000. Complementary areas of the internal top plate flow channels are shown. These areas are slightly raised tracks indicating a conductive surface finish by laser welding in one mode of manufacture in this embodiment. Other modes of manufacture of the cassette have been described above. Fluid inlet 810 and fluid outlet 824 are also shown in this view.

[0091] Figures 31C and 31D show the air side of midplate 1000 in one embodiment. As shown in Figure 31A, the air side of valve holes 808, 814, 816, 822 correspond to the holes on the fluid side of the midplate. As shown in Figures 33C and 33D, diaphragm 1220 completes valves 808, 814, 816, 822 and diaphragm 1226 completes pod pumps 820, 828. Metering pump 830 is completed by diaphragm 1224. Valves 808, 814, 816, 822, 832, 834, 836 are air actuated. The diaphragm is pulled away from the hole and liquid is drawn in. When the diaphragm is pressed towards the hole, liquid is forced through. Fluid flow is directed by opening and closing valves 808, 814, 816, 822, 832, 834, and 836.

[0092] Figures 31A and 31C show that the metering pump includes three holes 1002, 1004, and 1006. Hole 1002 draws air into the metering pump. A second hole 1004 pushes and displaces air into the spike or source container, which also draws liquid from the source container. A third hole 1006 pushes and displaces a second fluid from the metering pump 830 to point 826 in the fluid line.

[0093] Valves 832, 834, and 836 drive a second fluid metering pump. Valve 832 is a second fluid or spike valve. Valve 834 is an air valve, and valve 836 is a valve that controls the flow of fluid to region 826 of the fluid line.

[0094] 32A and 32B show the inside of bottom plate 1100. The inside of pod pumps 820, 828, metering pump 830, and the drive or air chambers for valves 808, 814, 816, 822, 832, 834, 836 are shown. Pod pumps 820, 828, metering pump 830, and valves 808, 814, 816, 822, 832, 834, 836 are driven by an air source. FIGS. 32C and 32D show the outside of bottom plate 1100. The air source is attached to this side of the cassette. In one embodiment, tubing is connected to the face of the valves and pump 1102. In some embodiments, the valves are ganged and more than one valve is driven by the same air line.

[0095] 33A and 33B show an assembled cassette 1200 with a container (or other source) 1202 of a second fluid. The container 1202 contains a source of the second fluid and is attached by a container attachment 1206 to a spike (not shown). The spike is mounted within the container attachment 1206 and faces upward so as to penetrate the top of the container 1202. The container 1202 is held on the opposite side of the container attachment 1206. The spike is in liquid communication with the liquid channel, similar to the recessed air passage shown in FIGS. 30C and 30D. As shown, an air filter 1204 is attached to a vent (not shown, shown in FIG. 30A as 906). Although not shown in FIG. 33A, a container pedestal (shown in FIG. 30A as 904) is located below the container attachment 1206.

[0096] In some examples, the metering pump is a fluid management system pump and can be monitored with a pressure transducer in conjunction with a reference chamber to determine the volume of fluid delivered. The fluid management system algorithm uses the change in pressure to calculate a volume measurement at the end of the fill stroke and the end of the deliver stroke. The difference in the calculated volumes at the end of the fill stroke and the end of the deliver stroke is the actual stroke volume. This actual stroke volume can be compared to the expected stroke volume for a given size chamber. If the actual volume and the expected volume differ significantly, the stroke is not properly completed and an error message is generated. The fluid management system is vented to atmosphere for fluid management system calibration. Alternatively, the system may be vented to a high pressure positive source and a low pressure negative source for fluid management system calibration. In some embodiments, the metering pump (e.g., an anticoagulant pump) is primed. Priming the pump removes air from the metering pump and fluid path and ensures that the pressure in the fluid container (e.g., an anticoagulant vial) is acceptable.

[0097] The metering pump can be designed so that the air in the pump chamber flows into the vial. The test involves closing all of the metering pump's fluid valves and measuring the outside volume, applying a vacuum to the pump's FMS chamber, opening the valves to introduce fluid from the vial into the pump chamber and measuring the outside volume (again), applying pressure to the FMS chamber, opening the valves to force the fluid back into the vial and measuring the outside volume (again). The change in outside volume caused by the fluid flow should correspond to the known volume of the pump chamber. If the pump chamber cannot be filled from the vial, the vial pressure is too low and air must be pumped in. Conversely, if the entire contents of the pump chamber cannot be transferred to the vial, the vial pressure is too high and some of the anticoagulant must be pumped out of the vial. The anticoagulant pumped out of the vial during the test can be discarded, for example, via a drain.

[0098] During normal delivery of heparin or other medication to the blood line, the pressure within the vial can be measured periodically. When the vial pressure approaches a predetermined threshold, e.g., below atmospheric pressure, the metering pump can first introduce air into the vial via the metering pump vent, helping to restore the vial pressure to normal and ensuring that a reasonably accurate amount of medication is withdrawn from the vial. When the vial pressure approaches a predetermined threshold above atmospheric pressure, the metering pump can refrain from blowing any more air into the vial before next withdrawing medication from the vial.

[0099] Figures 33C and 33D are exploded views of the assembled cassette 1200 shown in Figures 33A and 33B, respectively. In these figures, an embodiment of a pod pump diaphragm 1226 is shown. The diaphragm gasket provides a seal between the liquid chamber (in the top plate 900) and the air or actuation chamber (in the bottom plate 1100). The dimpled texture of the dome of the diaphragm 1226 provides additional space for air and fluid to escape the chambers, especially at the end of the stroke.

[0100] The system of the present invention further includes a balancing circuit, such as balancing circuit 143 shown in FIG. 3A. Although not required in some embodiments, the blood flow circuit is provided in the cassette. Within the balancing circuit, the flow of dialysate into and out of the dialyzer is such that equal amounts of dialysate enter and leave the dialyzer (although this balance may be altered in certain cases by the use of a bypass pump, as described below). Additionally, in some embodiments, the flow of dialysate is balanced by the dialyzer such that the pressure of the dialysate in the dialyzer is equal to the pressure of the blood passing through the blood flow circuit.

[0101] Additionally, in some instances, the dialysate flow is balanced by the dialyzer such that the pressure of the dialysate in the dialyzer is approximately equal to the pressure of the blood passing through the blood circuit. In some instances, the flow of blood through the blood flow circuit 141 and the dialyzer is synchronized with the flow of dialysate in the dialysate flow path through the dialyzer. Because fluid may pass through the semi-permeable membrane of the dialyzer, and because the balancing circuit pump operates at positive pressure, the balancing circuit pump can be timed using pressure and control data from the blood flow pump to synchronize the delivery stroke to the dialyzer with the delivery stroke of the blood pump.

[0102] A non-limiting example of a balancing circuit is shown in Figure 5. In the balancing circuit 143, dialysate flows from an optional ultrafiltration membrane 73 to one or more dialysate pumps 15 (two as shown in Figure 5). The dialysate pumps 15 in this figure include two pod pumps 161, 162, two balancing chambers 341, 342, and a pump 35 to bypass the balancing chambers. The balancing chambers are formed from a rigid chamber with a flexible partition that separates the chamber into two separate fluid compartments, configured such that entry of fluid into one compartment will expel fluid from the other compartment, and vice versa. Examples of pumps that can be used as pod pumps or balance chambers are disclosed, but are not limited to, in U.S. patent application Ser. No. 60 / 792,073, filed Apr. 14, 2006, and entitled "Extracorporeal Thermal Therapy System and Method," or U.S. patent application Ser. No. 11 / 787,212, filed Apr. 13, 2007, and entitled "Fluid Pumping System, Apparatus, and Method," both of which are incorporated herein by reference in their entireties. Additional examples of pod pumps are described in more detail below. As shown in FIG. 5, many of the valves are "ganged" or synchronized in pairs, whereby all valves in a pair open and close at the same time.

[0103] More specifically, in one embodiment, flow balancing works as follows: Figure 5 shows that in a first synchronized and controlled set of valves 211, 212, 213, 241, 242, valves 211, 212, 213 are ganged and valves 241 and 242 are ganged, and similarly in a second synchronized and controlled set of valves 221, 222, 223, 231, 232, valves 221, 222, 223 are ganged and valves 231 and 232 are ganged. At a first point in time, the first ganged set of valves 211, 212, 213, 241, 242 are open and the second ganged set of valves 221, 222, 223, 231, 232 are closed. Fresh dialysate flows into the balancing chamber 341 and used dialysate flows from the dialyzer 14 into the pod pump 161. Fresh dialysate does not flow into the balancing chamber 342 because valve 221 is closed. As fresh dialysate flows into the balancing chamber 341, the used dialysate in the balancing chamber 341 is forced out and out of the balancing circuit 143 (the used dialysate cannot enter the pod pump 161 because valve 223 is closed). At the same time, the pod pump 162 forces the dialysate in the pod pump into the balancing chamber 342 (through the open valve 213; valves 242 and 222 are closed, ensuring that the used dialysate flows into the balancing chamber 342). This causes the fresh dialysate contained in the balancing chamber 342 to be exhausted out of the balancing circuit 143 and into the dialysis machine 14. Additionally, the pod pump 161 draws the used dialysate from the dialysis machine 14 into the pod pump 161. This is further shown in FIG. 18A.

[0104] Once the pod pump 161 and balancing chamber 341 are filled with dialysate, the first set of valves 211, 212, 213, 241, 242 are closed and the second set of valves 221, 222, 223, 231, 232 are open. Fresh dialysate flows into balancing chamber 342 instead of balancing chamber 341 because valve 212 is closed and valve 221 is open. As fresh dialysate flows into balancing chamber 342, the used dialysate therein is forced out of the balancing circuit because valve 213 is closed. Because valve 232 is closed and valve 222 is open, the used dialysate is prevented from flowing to the pod pump 161. The fresh dialysate contained within balancing chamber 341 is thereby directed into the dialysis machine (because valve 241 is open and valve 212 is closed). At the end of this process, the pod pump 162 and balancing chamber 342 are filled with dialysate. This returns the state of the system to that at the beginning of this specification and the cycle repeats, ensuring a constant flow of dialysate to and from the dialyzer, which is further shown in Figure 18B.

[0105] A specific example is when a vacuum (e.g., 4 psi vacuum) is applied to a first ganged set of valves and a positive pressure (e.g., 20 psi air pressure) is applied to a second ganged set of valves, causing those valves to close (or vice versa). Each pod pump pumps dialysate into one of the volumes of one of the balance chambers 341, 342. By forcing dialysate into the volume of the balance chamber, an equal amount of dialysate is squeezed out of the other volume in the balance chamber by the septum. In each balance chamber, one volume is occupied by fresh dialysate towards the dialyzer and the other volume is occupied by used dialysate from the dialyzer. Thus, the volumes of dialysate entering and leaving the dialyzer are kept approximately equal.

[0106] It is noted that any valve associated with the balance chamber may be opened and closed at any suitable pressure. However, it may be advantageous to apply a lower or more controlled pressure than the pressure that ultimately holds the valve closed (the "holding pressure") from when the valve first begins to close until it is fully closed. Applying a pressure equal to the holding pressure to cause the valve to close may cause a transient pressure rise in the fluid lines sufficient to cause leakage in downstream valves that are already closed, adversely affecting the balance of dialysate flow to and from the dialyzer. Closing the inlet and / or outlet valves of the dialysate pump and balance chamber at a lower or more controlled pressure may improve the balance of dialysate flow to and from the dialyzer. In an embodiment, this may be accomplished, for example, by employing pulse width modulation ("PWM") to apply pressure to the fluid control lines of the valves. Without being limited to the following theory, it may be advantageous to use a moderate or controlled pressure for a "slow closing" valve, for example, for the following reasons: (1) In some instances, the pressure in the balance chamber may transiently exceed the holding pressure of the closed balance chamber outlet valve (e.g., caused by applying excessive pressure to close the balance chamber inlet valve against the mass of fluid behind the valve septum). The transient pressure rise in the fluid line may overcome the holding pressure of the closed outlet valve, causing fluid to leak between the two sides of the balance chamber, resulting in an imbalance in fluid delivery. (2) Additionally, the presence of air or gas between the balance chamber and the balance chamber valve, combined with rapid valve closure, may cause excess fluid to be swept into the balance chamber rather than balanced by fluid from the other side of the balance chamber.

[0107] When the septum approaches the walls of the balancing chambers (causing one volume of the balancing chamber to approach a minimum and the other volume to approach a maximum), positive pressure is applied to the first ganged set of valves, causing them to close. Vacuum is applied to the second ganged set of valves, causing them to open. The pod pump pumps dialysate into one of the other volumes of the balancing chambers 341, 342. Again, an equal amount of dialysate is squeezed out of the other volume of the balancing chamber by the septum, forcing dialysate into the balance chamber volume. In each balancing chamber, one volume is occupied by fresh dialysate towards the dialyzer, and the other volume is occupied by used dialysate from the dialyzer. Thus, the volumes of dialysate entering and leaving the dialyzer are kept equal.

[0108] FIG. 5 further illustrates a bypass pump 35 capable of directing dialysate flow from the dialysis machine 14 through the balancing circuit 143 without passing through both pod pumps 161 or 162. In this figure, the bypass pump 35 is a pod pump similar to those described above, with a rigid chamber and a flexible partition separating each chamber into a fluid compartment and a control compartment. The pump may be the same as or different from the other pod pumps and balancing chambers described above. For example, the pump may be a pump as described in U.S. patent application Ser. No. 60 / 792,073, filed Apr. 14, 2006, and entitled "Extracorporeal Heat Therapy System and Method," or U.S. patent application Ser. No. 11 / 787,212, filed Apr. 13, 2007, and entitled "Fluid Pumping System, Apparatus and Method," each of which is incorporated herein in its entirety. Pod pumps are described in more detail below.

[0109] When a control fluid is used to drive this pump, the dialysate is pumped through the dialyzer without balancing the blood flow through the dialyzer. This causes a flow of fluid from the patient through the dialyzer to the drain. The bypass is useful, for example, to reduce the amount of fluid the patient has, which is usually increased by the patient's inability to lose fluid (mainly water) through the kidneys. As shown in FIG. 5, the bypass pump 35 is controlled by a control fluid (e.g., air) independently of the driving of the pod pumps 161 and 162. This configuration makes it easy to control the removal of fluid from the patient without driving the balancing pump to drain the fluid from the patient.

[0110] To obtain a balanced flow across the dialyzer, the blood flow pump, the pumps in the balancing circuit, and the pumps in the directing circuit (described below) are driven in a coordinated manner to ensure that the flow into the dialyzer is equal to the flow normally out of the dialyzer. When ultrafiltration is required, the ultrafiltration pump (if there is one) is driven independently of some or all of the other blood and dialysate pumps to obtain the desired ultrafiltration rate.

[0111] To prevent dialysate outgassing, the balancing circuit pump is always held at a pressure greater than atmospheric pressure. In contrast, however, the blood flow pump and directing circuit pump use a pressure less than atmospheric pressure to pull the diaphragm toward the chamber wall for the fill stroke. The balancing circuit pump can use information from the blood flow pump to operate in a balanced flow mode, potentially to move fluid across the dialyzer, and for the balancing circuit pump to operate at a positive pressure.

[0112] In an embodiment, when operating in the balanced mode, in the absence of delivery pressure from the blood pump, the diaphragm of the balancing circuit pump pushes fluid across the dialyzer to the blood so that the pods that replace it in the balancing circuit do not fill completely. Thus, the blood pump dynamically reports when there is a stroke. The balancing pump runs when the blood pump is stroking. When the blood pump is not delivering blood, the valves that control the flow from the dialyzer to the balancing pump (and the other balancing valves associated with these valves as described above) are closed, preventing fluid from moving from the blood side to the dialysate side. When the blood pump is not delivering, the balancing pump effectively freezes, and the stroke continues when the blood pump begins to deliver again. The filling pressure of the balancing pump is set to a minimum positive value to ensure that the pump drives above atmospheric pressure with minimal impedance. Additionally, the balance pump delivery pressure is set to the blood flow pump pressure to normally match the pressure on both sides of the dialyzer, minimizing flow across the dialyzer on the inner pump stroke.

[0113] In some instances, it may be advantageous to have the dialysate pump deliver dialysate to the dialyzer at a pressure higher than the delivery pressure of the blood pump. This helps, for example, to ensure that clean dialysate is delivered to the dialyzer in the entire chamber. In an embodiment, the delivery pressure on the dialysate pump is set high enough to cause the internal pump to finish its stroke, but not so high that it stops the flow of blood in the dialyzer. Conversely, in some instances, when the dialysate pump is receiving used dialysate from the dialyzer, it may be advantageous to set the pressure in the dialysate pump lower than the outlet pressure on the blood side of the dialyzer. This helps to ensure that the receiving dialysate chamber can always be filled, and thus that there is enough dialysate available to complete a full stroke in the balance chamber. The flows across the semi-permeable membranes caused by such pressure differences tend to cancel each other out, and otherwise the pump algorithm attempts to match the average pressures on the dialysate and blood sides of the dialyzer.

[0114] Convection across the dialyzer membrane may be beneficial because the constant, repetitive shifting of fluid in and out of the dialyzer, while not resulting in net ultrafiltration, still helps prevent the formation of clots in the blood tubing and dialyzer. This, in turn, allows for lower heparin dosages, extends the useful life of the dialyzer, and facilitates cleaning and reuse of the dialyzer. Backflushing has the added benefit of further promoting solute removal by convection. In another embodiment, by slightly adjusting the synchronization of the blood transport stroke and the dialysate transport stroke through the dialyzer, a sort of continuous backflushing across the dialyzer membrane can also be achieved.

[0115] In therapy, it is preferable to keep the blood flow as constant as possible, since stagnant blood flow can lead to blood clotting. Additionally, when the velocity of the transport fluid of the blood flow pump is discontinuous, the balancing pump must pause the stroke frequently, which causes the dialysis fluid velocity to be discontinuous and / or low.

[0116] However, for various reasons, the flow through the blood pump becomes discontinuous. For example, pressure is limited to +600 mmHg (approximately 79.993 kPa) to -350 mmHg (approximately -46.662 kPa) in the blood pump to provide a safe pump pressure to the patient. For example, in a dual needle flow, the two pod pumps of the blood pump can be programmed to run 180° out of phase with each other. This phase is always obtained if there is no pressure limit. However, these pressures are limited to provide a safe blood flow to the patient. If the impedance is high on the fill stroke (due to small needles, very viscous blood, difficult access to the patient, etc.), a negative pressure limit is reached and the fill fluid rate becomes slower than the desired fill fluid rate. Thus, the delivery stroke must wait for the previous fill stroke to pause and complete the delivery fluid rate of the blood pump. Similarly, in a single needle flow, the blood flow pump is driven at 0° phase and the pod pumps of the two blood flow pumps are emptied and filled simultaneously. When both pod pumps are filled, the volume of the two pod pumps is delivered. Therefore, the single needle flow is discontinuous.

[0117] One way to control the pressure saturation limit is to limit the desired fluid rate to the slowest of the fill and delivery strokes. This will result in a slower flow rate carrying the blood, but the flow rate will be known and will always be continuous, resulting in a more accurate and more continuous dialysate flow rate. Another way to make the blood flow rate more continuous in one needle drive is to use the maximum pressure to fill the pod so that the fill time is minimized. The desired delivery time can be set to the total time of the desired stroke minus the time taken for the fill stroke. However, if the blood flow rate cannot be kept constant, the dialysate flow rate is adjusted to compensate for the time the dialysate pump stops when the blood flow pump fills if the blood flow rate carrying the dialysate stream is high, by a set value. If this is done with the correct timing, the average of the dialysate flow rate over multiple strokes can match the desired dialysate flow rate.

[0118] Figures 34-36 show non-limiting examples of balancing cassettes. In one configuration of the cassette shown in Figure 34A, the valves are ganged to operate simultaneously. In one embodiment, four ganged valves 832, 834, 836, 838 are provided. In an embodiment, the ganged valves are driven by the same air line. However, in other embodiments, each valve has a corresponding air line. In the embodiment, the ganged valves effect fluid flow as described above. In an embodiment, the ganged valves further ensure that the appropriate valves are opened and closed to create the desired fluid path.

[0119] In this embodiment, the fluid valve is a volcano valve as disclosed in detail herein. Although the fluid paths in the various embodiments are outlined with respect to specific flow paths, the flow paths may vary based on the actuation of the valves and pumps. Additionally, the terms inlet and outlet as well as first and second fluid are used (in this cassette and other cassettes described below) for descriptive purposes only. In other embodiments, the inlet may be an outlet and further the first and second fluid may be different fluid types or the same fluid type or composition.

[0120] 35A-35E show an embodiment of a cassette top plate 1000. FIGS. 35A and 35B are plan views of the top plate 1000. In this embodiment, the pod pumps 820, 828 and balancing pods 812, 822 of the top plate are formed identically. In this embodiment, the pod pumps 820, 828 and balancing pods 812, 822 have a total capacity of 38 ml when assembled with the bottom plate. However, in various embodiments, the total capacity may be greater or less than that of this embodiment. A first fluid inlet 810 and a second fluid outlet 816 are shown.

[0121] 35C and 35D are bottom views of the top plate 1000. The flow paths are shown in this view. These flow paths correspond to the flow paths of the midplate 900 shown in FIG. 34B. The top plate 1000 and the top of the midplate form the liquid or fluid side of the cassette for the pod pumps 820, 828 and on one side of the balancing pods 812, 822. Thus, most of the fluid flow paths are provided in the top plate and midplate. The other side of the balancing pods 812, 822 is provided on the inside of the bottom plate, as shown in FIGS. 36A and 36B, but not shown here.

[0122] Figures 35C and 35D further illustrate that the pod pumps 820, 828 and the balancing pods 812, 822 include grooves 1002. The grooves 1002 as shown have a predetermined shape. However, in other embodiments, the shape of the grooves 1002 can be any desired shape. Figures 35C and 35D illustrate an embodiment of the shape. In an embodiment, the grooves 1002 form a passageway between the fluid inlet side and the fluid outlet side of the pod pumps 820, 828 and the balancing pods 812, 822.

[0123] The grooves 1002 provide a flow path so that when the bulkhead is at the end of the stroke there is a flow path between the inlet and outlet so that pockets of fluid or air are not trapped in the pod pumps or balancing pods. The grooves 1002 are included on both the liquid and air sides of the pod pumps 820, 828 and balancing pods 812, 822 (see Figures 36A and 36B, which relate to the air sides of the pod pumps 820, 828 and the opposite sides of the balancing pods 812, 822).

[0124] In one embodiment, the liquid sides of the pod pumps 820, 828 and balancing pods 812, 822 include a feature that provides continuous inlet and outlet flow paths and a continuous outer ring 1004. This feature allows a seal (not shown) to be formed against the diaphragm to be retained.

[0125] 35E is a side view of an embodiment of the top plate 1000. The continuous outer ring 1004 of the pod pumps 820, 828, and the balancing pods 812, 822 are shown. 36A-36E show the bottom plate 1100. In Figs. 36A and 36B, the inner surface of the bottom plate 1100 is shown. The inner surface is the side that contacts the bottom surface of the mid-plate (not shown here) shown in Fig. 34E. The bottom plate 1100 is attached to an air line (not shown). Corresponding inlet holes 1106 for air to drive the pod pumps 820, 828 and valves (not shown here) shown in Fig. 34E are provided in the mid-plate. Holes 1108, 1110 correspond to the second fluid inlet 824 and second fluid outlet 826, respectively, shown in Fig. 34C. Also shown are the corresponding halves of the pod pumps 820, 828 and balancing pods 812, 822, as well as the grooves 1112 for the flow paths. Unlike the top plate, the halves of the bottom plate corresponding to the pod pumps 820, 828 and balancing pods 812, 822 clarify the distinction between the pod pumps 820, 828 and the balancing pods 812, 822. The pod pumps 820, 828 have air passages in the second half of the bottom plate, while the balancing pods 812, 822 have the same structure as the half in the top plate. Additionally, the balancing pods 812, 822 are fluid balancers, whereby both sides of a bulkhead, not shown, contain liquid flow paths, and the pod pumps 820, 828 are pressure pumps that pump liquid, whereby one side contains the liquid flow paths and the other side, shown in the bottom plate 1100, contains an air driven chamber or air fluid path.

[0126] In one embodiment of the cassette, sensor elements are incorporated into the cassette to sense various properties of the fluid being pumped. In one embodiment, three sensor elements are included. In one embodiment, the sensor elements are provided in a sensor cell 1114. The cell 1114 houses three sensor elements in sensor element housings 1116, 1118, and 1120. In one embodiment, two of the sensor housings 1116 and 1118 house conductivity sensor elements and the third sensor element housing 1120 houses a temperature sensor element. The conductivity sensor elements and temperature sensor elements may be any conductivity sensor element or temperature sensor element known in the art. In one embodiment, the conductivity sensor elements are graphite posts. In another embodiment, the conductivity sensor elements are formed from stainless steel, titanium, platinum, or other metals that are coated for corrosion protection but still have electrical conductivity. The conductivity sensor elements may include electrical wires that transmit probe information to a controller or other device. In one embodiment, the temperature sensor is a thermistor embedded in a stainless steel probe. In alternative embodiments, the cassette may have no sensors, only a temperature sensor, one or more conductivity sensors, or one or more other types of sensors. In some embodiments, the sensor elements may be located outside the cassette, in a separate cassette, or connected to the cassette by a fluid line.

[0127] Figures 36A and 36B further show the drive side of metering pump 830, as well as the corresponding air inlet hole 1106 for air to power the pump. Figures 36C and 36D show the outside of bottom plate 1100. Shown are the valves, pod pumps 820, 828, and airline connection points 1122 for metering pump 830. Again, balancing pods 812, 822 do not have airline connection points and are therefore not powered by air. Also shown are corresponding openings in bottom plate 1100 for second fluid outlet 824 and second fluid inlet 826.

[0128] FIG. 36E is a side view of the bottom plate 1100. In the side view, a lip 1124 surrounds the bottom plate 1100 on the inside. The lip 1124 is raised and continuous, providing a connection point for a bulkhead (not shown). The bulkhead rests on this continuous raised lip 1124, thereby providing a seal between the pod pumps 820, 828 and half of the balancing pods 812, 822 on the bottom plate 1100 and the pod pumps 820, 828 and half of the balancing pods 812, 822 on the top plate (not shown here) shown in FIGs. 35A-35D.

[0129] As described above, the dialysate flows from the directing circuit, optionally through a heater and / or through an ultrafiltration membrane, to the balancing circuit. In an embodiment, but not necessarily, the directing circuit is provided in the cassette. FIG. 3A shows a directing circuit 142 as an example of a directing circuit. The directing circuit 142 can perform several different functions in this embodiment. For example, dialysate flows from a dialysate supply (such as from a mixing circuit, as described below) through the directing circuit to the balancing circuit, and used dialysate flows from the balancing circuit to drain. The dialysate flows by actuation of one or more pumps included in the directing circuit. In an embodiment, the directing circuit includes a dialysate tank, which contains dialysate prior to moving the dialysate to the balancing circuit. The dialysate tank allows, in an embodiment, the rate of production of dialysate to differ from the rate of use of dialysate by the dialysis device in the system. The directing circuit also directs water from the water supply to the mixing circuit (if there is one). Additionally, as described above, the blood flow circuit communicates with the directing circuit for operations such as disinfection.

[0130] Thus, in some embodiments, dialysate is prepared on demand, eliminating the need to store large amounts of dialysate. For example, the dialysate is prepared and then held in a dialysate tank 169. A dialysate valve 17 controls the flow of dialysate from the tank 169 to the dialysate circuit 20. The dialysate is filtered and / or heated prior to being sent to the dialysis machine 14. A contaminant treatment valve 18 is used to control the flow of used dialysate from the dialysate circuit 20.

[0131] FIG. 6 shows an example of a directing circuit, but is not limited thereto. In this figure, directing circuit 142 communicates dialysate from the dialysate supply through dialysate pump 159, heater 72, and ultrafiltration membrane 73 to dialysate tank 169 before entering the balancing circuit as described above. As shown, the dialysate in the dialysate flow path flows from the dialysate supply to the dialysate tank, pump, heater, and ultrafiltration membrane (in that order), although other orders are possible in other examples. Heater 72 is used to heat the dialysate to body temperature and / or to heat blood in the blood flow circuit so that the blood returned to the patient is at body temperature as the dialysate heats it. Ultrafiltration membrane 73 is used to remove pathogens, pyrogens, etc. present in the dialysate as described below. The dialysate flows through the balancing circuit and is directed to the dialysis machine.

[0132] The dialysate tank 169 may be made of any suitable material and of any suitable size for storing dialysate prior to use. For example, the dialysate tank 169 may be made of plastic, metal, etc. The dialysate tank may be made of materials similar to those used to form the pod pumps, as described above.

[0133] The flow of dialysate through the directing circuit 142 is controlled (at least in part) by operation of the dialysate pump 159. Additionally, the dialysate pump 159 controls the flow through the balancing circuit. For example, as described above in FIG. 5, fresh dialysate from the directing circuit flows to balancing chambers 341 and 342 of the balancing circuit 143. The pump 159 is used to pump the fresh dialysate through these balancing chambers. In an embodiment, the dialysate pump 159 comprises a pod pump similar to those described above. The pod pump includes rigid chambers with flexible diaphragms that separate each chamber into a fluid compartment and a control compartment. The control compartment is coupled to a source of controlled fluid, such as an air source. Examples of pumps that may be used as pod pumps or balance chambers are disclosed, but are not limited to, in U.S. patent application Ser. No. 60 / 792,073, filed Apr. 14, 2006, and entitled "Extracorporeal Thermotherapy System and Method," or U.S. patent application Ser. No. 11 / 787,212, filed Apr. 13, 2007, and entitled "Fluid Pumping System, Apparatus and Method," both of which are incorporated herein in their entireties. Pod pumps are described in further detail below.

[0134] After passing through pump 159, the dialysate flows to a heater, such as heater 72 in FIG. 6. The heater is any suitable heating device for heating the dialysate, such as an electrical resistance heater, as known to those skilled in the art. The heater may be separate from the directing circuit, as shown in FIG. 3A, or the heater may be integrated into the directing circuit or into another circuit (e.g., the balancing circuit).

[0135] In an embodiment, the dialysate is heated to a temperature that does not cool the blood passing through the dialyzer. For example, the temperature of the dialysate is controlled so that the dialysate is at or above the temperature of the blood passing through the dialyzer. In the above embodiment, the blood is somewhat heated as described above to offset the heat loss caused by the blood passing through the various elements of the blood flow circuit. Additionally, as described below, in an embodiment, the heater is coupled to a control system so that incorrectly heated dialysate (i.e., dialysate that is too heated or too cold) is recirculated (e.g., back to the dialysate tank) instead of passing through the dialyzer via line 731. The heater may be integrally formed as part of a fluid circuit, such as a directing circuit or a balancing circuit, or, as shown in FIG. 3A, the heater may be a separate element in the dialysate flow path.

[0136] In some embodiments, the heater is also used for disinfection or sterilization. For example, water passes through the hemodialysis system and is heated using a heater to a temperature that allows for disinfection or sterilization, such as at least about 70° C., at least about 80° C., at least about 90° C., at least about 100° C., at least about 110° C., etc. In some embodiments, the water is recirculated through the various elements as described below, and / or heat losses within the system are minimized by the heater heating the water to the disinfection or sterilization temperatures described below.

[0137] The heater includes a control system that can control the heater as described above (e.g., heating the dialysate to body temperature for dialysis of the patient, heating the water temperature to a disinfecting temperature for purifying the system).

[0138] Non-limiting examples of heater controllers are described below. The controller is selected to handle pulsating flow rates and various fluid velocities as well as various inlet fluid temperatures. Additionally, the heater control must function properly when flow is directed to each of the different flow paths (dialysis, disinfection, recirculation, etc.). In one embodiment, the heater controller is used on the SIP1 board with an IR (infrared) temperature sensor on the UF membrane and an IR temperature sensor on the tank. In another embodiment, the board is placed in a box with less heat loss and uses a conductivity sensor for the inlet temperature sensor. In another embodiment, the controller is a simple proportional controller using both the tank (heater inlet) and UF membrane (heater outlet) temperatures. For example: powerHeater = massFlow * ((tankPGain * errorTank) + (UFPGain * errorUF) PowerHeater = heater duty command (0 to 100%); MassFlow = fluid mass flow rate; TankPGain = proportional gain for the tank or inlet temperature sensor; ErrorTank = difference between the tank or inlet temperature sensor and desired temperature; UFPGain = proportional gain for the ultrafiltration membrane or outlet temperature sensor; ErrorUF = uf or difference between the outlet temperature sensor and desired temperature.

[0139] The PWM command is generated from the heater duty cycle command (0-100%). In an embodiment, the controller reduces the mass flow rate if the desired temperature is not maintained and the heater becomes saturated.

[0140] The heater controls described above are exemplary only and it is understood that other heater control systems and other heaters are possible in alternative embodiments of the invention. The dialysate is further filtered to remove contaminants, infectious organisms, pathogens, pyrogens, debris, etc., using, for example, an ultrafiltration membrane. The filter is placed in a suitable location in the dialysate flow path, between the directing circuit and the balancing circuit, as shown in FIG. 3A, and / or the ultrafiltration membrane is incorporated into either the directing circuit or the balancing circuit. When an ultrafiltration membrane is used, it is selected to have a mesh size that prevents the above types from passing through the filter. For example, the mesh size is about 0.3 micrometers or less, about 0.2 micrometers or less, about 0.1 micrometers or less, or about 0.05 micrometers or less, etc. One skilled in the art will recognize that filters such as ultrafiltration membranes are often readily available on the market.

[0141] In an embodiment, the ultrafiltration membrane is operated such that contaminants from the filter (e.g., the retentate stream) are transferred to a contaminant stream, such as contaminant line 39 in FIG. 6. In an embodiment, the amount of dialysate flowing in the retentate stream can be controlled. For example, if the retentate is too cold (i.e., heater 72 does not turn on or heater 72 does not heat the dialysate to a sufficient temperature), the entire dialysate stream (or at least a portion of the dialysate) is diverted to contaminant line 39 and optionally recirculated to dialysate tank 169 using line 48. The flow from the filter may be further monitored for a variety of reasons using temperature sensors (e.g., sensors 251 and 252), conductivity sensors (to verify dialysate concentration, e.g., sensor 253), etc. Examples of such sensors are described below. Other examples are disclosed, but are not limited to, in U.S. Patent Application Serial No. 12 / 038,474, entitled "SENSOR INSTRUMENT SYSTEM, APPARATUS AND METHOD" (Docket No. F63). This document is incorporated herein in its entirety.

[0142] It can be said that the ultrafiltration membrane and the dialyzer are redundant screening methods for the removal of contaminants, infectious organisms, pathogens, pyrogens, and debris (although in other embodiments the ultrafiltration membrane is not provided). Thus, for contaminants to pass from the dialysate to the patient, the contaminants must pass through both the ultrafiltration membrane and the dialyzer. If one cannot filter, the other can still sterilize and prevent the contaminants from passing into the patient's blood.

[0143] Directing circuit 142 can further direct spent dialysate through a balancing circuit to a drain, e.g., through contaminant line 39 to drain 31 in FIG. 6. The drain can be, for example, a local drain or a separate container for containing contaminants (e.g., spent dialysate) to be suitably located. In an embodiment, one or more check valves or "one-way" valves (e.g., check valves 215 and 216) are used to control the flow of contaminants from the directing circuit and the system. Additionally, in an embodiment, a blood leak sensor (e.g., sensor 258) is used to determine whether blood is leaking through the dialyzer into the dialysate flow path.

[0144] Additionally, the directing circuit 142 receives water from a water supply 30, e.g., a container of water, such as a bag, and / or from a device capable of producing water, such as a commercially available reverse osmosis device. In an embodiment, as known to those skilled in the art, the water entering the system is set to a predetermined purity, e.g., has an ion concentration below a predetermined value. The water entering the directing circuit 142 travels to various locations, e.g., to a mixing circuit for producing fresh dialysate, and / or to a contaminant line 39. As will be described in an embodiment below, the valves to the drain 31, the various recirculation lines are opened, and a conduit 67 is connected between the directing circuit 142 and the blood flow circuit 141 so that the water flows continuously throughout the system. If the heater 72 is also activated, the water passing through the system is continuously heated to a temperature sufficient to disinfect the system. The disinfection method is described in detail below.

[0145] A non-limiting example of a balancing cassette is shown in Figures 41-45. Figures 41A and 41B show the outside of the top plate 900 of one embodiment of the cassette. The top plate 900 contains one half of the pod pumps 820, 828. This half is the half of the fluid or liquid source through which the source flow flows. The inlet and outlet pod pump flow paths are shown. These flow paths lead to each of the pod pumps 820, 828.

[0146] The pod pump 820, 828 includes elevated flow passages 908, 910. The elevated flow passages 908, 910 allow fluid to continue to flow through the pod pump 820, 828 after a bulkhead (not shown) reaches the end of the stroke. Thus, the elevated flow passages 908, 910 minimize bulkheads that can trap air or fluid in the pod pump 820, 828 or block the inlet or outlet of the pod pump 820, 828 preventing flow. In this embodiment, the elevated flow passages 908, 910 have a predetermined size. In alternative embodiments, the elevated flow passages 908, 910 are larger or narrower. In yet another embodiment, the elevated flow passages 908, 910 can be any size since the goal is to control the flow rate to obtain a desired flow velocity of the fluid or to obtain a desired drive of the fluid. Thus, any dimensions disclosed herein for raised fluid lines, pod pumps, valves, or other aspects are merely exemplary and alternative embodiments. Other embodiments will be apparent. Figures 41C and 41D show the inside of the top plate 900 of the cassette in this embodiment. Figure 41E is a side view of the top plate 900.

[0147] Figures 42A and 42B show the fluid or liquid side of the midplate 1000. Figures 41C and 41D show the areas that complement the flow channels on the inner top plate. These areas are slightly raised tracks that indicate a conductive surface finish by laser welding in one mode of manufacture in this embodiment. Other modes of manufacture of the cassettes are described above.

[0148] Figures 42C and 42D show the air side of midplate 1000 in this embodiment, or the side that faces the bottom plate (not shown here) shown in Figures 43A-43E. Air side valve holes 802, 808, 814, 816, 822, 836, 838, 840, 842, 844, and 856 correspond to the fluid side holes of midplate 1000 shown in Figures 42A and 42B. As shown in Figures 44C and 44D, diaphragm 1220 completes pod pumps 820 and 828, and diaphragm 1222 completes valves 802, 808, 814, 816, 822, 836, 838, 840, 842, 844, and 856. The valves 802, 808, 814, 816, 822, 836, 838, 840, 842, 844, 856 are actuated by air pressure and when the septum is pulled away from the hole, liquid or fluid flows. When the septum is pressed towards the hole, fluid flow is prevented. Fluid flow is directed by opening and closing the valves 802, 808, 814, 816, 822, 836, 838, 840, 842, 844, 856. Figures 43A and 43B are views of the inside of the bottom plate 1100. The interior of the pod pumps 820, 828 and the actuation or air chambers of the valves 802, 808, 814, 816, 822, 836, 838, 840, 842, 844, 856 are shown. The pod pumps 820, 828 and valves 802, 808, 814, 816, 822, 836, 838, 840, 842, 844, 856 are driven by an air source of air. The outside of the bottom plate 1100 is shown in Figures 43C and 43D. The air source is attached to this side of the cassette. In one embodiment, tubing is connected to the valves and tubing of the pump 1102. In an embodiment, the valves are ganged and multiple valves are driven by the same air line.

[0149] 44A and 44B show an assembled cassette 1200. An exploded view of the assembled cassette 1200 shown in FIGS. 44A and 44B is shown in FIGS. 12C and 12D. In these figures, an embodiment of a pod pump diaphragm 1220 is shown. The diaphragm gasket seals between the liquid chamber (in the top plate 900) and the air or actuation chamber (in the bottom plate 1100). In an embodiment, the dome texture of the diaphragm 1220 provides additional space for air and liquid to escape the chamber, especially at the end of the stroke. In an alternative embodiment of the cassette, the diaphragm includes a double gasket. The double gasket feature in the preferred embodiment is where both sides of the pod pump contain liquid or where it is desired to seal both sides of the chamber. In these embodiments, a lip that complements the gasket or other feature (not shown) is added to the interior bottom plate 1100, whereby the gasket seals the pod pump chamber in the bottom plate 1100.

[0150] 45 is a cross-sectional view of the cassette pod pump 828, showing details of the attachment of the bulkhead 1220. Again, in this embodiment, the gasket of the bulkhead 1220 is sandwiched by the mid-plate 1000 and bottom plate 1100. The edge of the mid-plate 1000 has features that allow the gasket to seal the chamber of the pod pump 828 attached to the top plate 900.

[0151] Figure 45 is a cross-sectional view of valves 834, 836 of the assembled cassette, showing that in this embodiment the septum 1220 is assembled and positioned by being sandwiched between the midplate 1000 and the bottom plate 1100. Additionally, the cross-sectional view of Figure 45 shows valve 822 of the assembled cassette, showing that the septum 1222 is positioned by being sandwiched between the midplate 1000 and the bottom plate 1100.

[0152] In an embodiment, the dialysate is prepared separately and delivered to the system for use in the directing circuit. In an embodiment, however, the dialysate is prepared in the mixing circuit. The mixing circuit is driven to form the dialysate at a suitable time. For example, the dialysate is produced during and / or prior to dialysis of the patient (e.g., the dialysate is contained in a dialysate tank). To form the dialysate in the mixing circuit, water (e.g., from a water supply, optionally provided to the mixing circuit by the directing circuit) is mixed with various dialysate ingredients. For example, suitable dialysate ingredients of sodium bicarbonate, sodium chloride, and / or acid, as described above, are known to those skilled in the art. The dialysate is formed on demand, and therefore need not be contained in large quantities in the dialysate tank, in certain cases.

[0153] FIG. 7A shows a non-limiting example of a mixing circuit that may be provided in a cassette in an embodiment. In FIG. 7A, water from the directing circuit flows into the mixing circuit 25 by driving a pump 180. In an embodiment, a portion of the water is delivered to the source 49, for example, for use in transporting the ingredients through the mixing circuit. As shown in FIG. 7A, the water is delivered to the bicarbonate source 28 (which further includes sodium chloride in an embodiment). In an embodiment, the sodium chloride or sodium bicarbonate is provided in a powdered or granular form, which is moved by the action of water. The bicarbonate from the bicarbonate source 28 is delivered by the bicarbonate pump 183 to the mixing line 186, which also contains the water from the directing circuit. The acid (in the form of a fluid) from the acid source 29 is also pumped into the mixing line 186 by the acid pump 184. The ingredients (water, bicarbonate, acid, sodium chloride, etc.) are mixed in the mixing chamber 189 to form the dialysis fluid that flows from the mixing circuit 25. Conductivity sensors 178 and 179 are provided along the mixing line 186 to ensure that each ingredient is added at the proper concentration as it is added to the mixing line.

[0154] In an embodiment, pump 180 comprises one or more pod pumps similar to those described above. A pod pump includes rigid chambers with flexible partitions separating each chamber into a fluid compartment and a control compartment. The control compartment is coupled to a source of controlled fluid, such as an air source. Examples of pod pumps are disclosed, but are not limited to, in U.S. patent application Ser. No. 60 / 792,073, filed Apr. 14, 2006, and entitled "Extracorporeal Thermotherapy System and Method," or U.S. patent application Ser. No. 11 / 787,212, filed Apr. 13, 2007, and entitled "Fluid Pump System, Apparatus and Method," both of which are incorporated herein by reference in their entireties. Similarly, in an embodiment, pumps 183 and / or 184 are each pod pumps. Further details of pod pumps are provided below.

[0155] In an embodiment, one or more pumps have a pressure sensor that monitors the pressure of the pump to ensure that the pump compartment is completely filled and delivered. For example, to ensure that the pump performs a full stroke of fluid, (i) fills the compartment, (ii) closes both fluid valves, (iii) applies pressure to the compartment by opening a valve between the positive air tank and the compartment, (iv) closes the positive pressure valve, leaving pressurized air in the passage between the valve and the compartment, (v) opens the fluid valve, allowing fluid to flow from the pump compartment, and (vi) monitors the pressure drop in the compartment as fluid flows from the pump compartment. The pressure drop corresponding to a full stroke is consistent and depends on the initial pressure, the volume occupied between the valve and the compartment, and / or the stroke volume. However, in other embodiments of the pod pumps disclosed herein, a reference volume compartment is used, and the volume is defined by pressure and volume data.

[0156] Since the volume delivered by the water pump or other pumps is directly related to the conductivity measurement, the volume measurement is used as a cross-check of the dialysate composition being formed, thereby ensuring that the dialysate composition remains safe even in the event of inaccurate conductivity measurements during therapy.

[0157] FIG. 7B is a schematic diagram of another example of a mixing circuit that may be provided in a cassette in accordance with an embodiment. The mixing circuit 25 in this figure includes a pod pump 181 that pumps water from a water supply along line 186. Various ingredients for making the dialysis solution are introduced into the water. Another pump 182 pumps from the water supply to a source 28 (e.g., a container) that holds sodium bicarbonate and / or to a source 188 that holds sodium chloride. A third pump 183 introduces the dissolved bicarbonate into the mixing line 186 (where they are mixed in a mixing chamber 189), and a fourth pump 185 introduces the dissolved sodium chloride into the line 186 (where they are mixed in a mixing chamber 191). A fifth pump 184 introduces acid into the water prior to passing through the first pump 181. The mixing is monitored using conductivity sensors 178, 179, 177. Each conductivity sensor measures the conductivity after a given ingredient is added to the mixing line 186 to ensure that the proper amount or concentration of the ingredient has been added. Examples of such sensors are described below. Further examples are disclosed, but are not limited to, in U.S. patent application Ser. No. 12 / 038,474, entitled "SENSOR INSTRUMENT SYSTEM, APPARATUS AND METHODS," Docket No. F63, which is incorporated herein by reference in its entirety.

[0158] As shown in FIG. 3B, in this embodiment, the mixing circuit 25 is connected to two sources, a source of acid concentrate 27, and a source of sodium bicarbonate (NaHCO 3 3B illustrates the use of combined sources of sodium chloride (NaCl) and sodium phosphate (SAP) to make up the dialysate. In the embodiment shown in FIG. 3B, the dialysate making up system 25 includes multiples of each source. In the embodiment, the system is continuously powered, with redundant sources of dialysate allowing the system to function continuously, so that when one set of sources is depleted, the system can use the redundant sources and the first set of sources is replaced. This process is repeated as necessary, for example, until the system is interrupted.

[0159] Non-limiting examples of balancing cassettes are shown in Figures 34-36. In the fluid-flow cassette shown in Figure 37, the valves are each open. In this embodiment, the valves are opened by air pressure. Furthermore, in this embodiment, the fluid valves are volcano valves as disclosed in detail herein.

[0160] 38A and 38B show the top plate 1100 of the cassette in one embodiment. In this embodiment, the pod pumps 820, 828 and mixing chamber 818 of the top plate 1100 are similarly formed. In this embodiment, the pod pumps 820, 828 and mixing chamber 818, when assembled with the bottom plate, provide a total volume of 38 ml. However, in alternate embodiments, the mixing chamber may be of any size desired.

[0161] Figure 38B is a bottom view of the top plate 1100. The fluid channels are shown in this view. These channels correspond to the channels in the mid-plate 1200 shown in Figures 39A-39B. The tops of the top plate 1100 and mid-plate 1200 form the liquid or fluid side of the cassette for the pod pumps 820, 828 and for one side of the mixing chamber 818. Thus, most of the fluid flow paths are in the top plate 1100 and mid-plate 1200. The first fluid inlet 810 and first fluid outlet 824 are shown in Figure 39B.

[0162] In Figures 38A and 38B, the pod pumps 820, 828 include a groove 1002 (which in an alternative embodiment is a groove). The groove 1002 is shown having a certain size and shape, but in alternative embodiments the size and shape of the groove 1002 can be any suitable size and shape. One embodiment's size and shape are shown in Figures 38A and 38B. In all embodiments, the groove 1002 forms a passageway on the fluid inlet side and the fluid outlet side of the pod pumps 820, 828. In an alternative embodiment, the groove 1002 is a groove in the wall of the internal pump chamber of the pod pump.

[0163] The grooves 1002 create a flow path so that even when the septum is at end stroke, a flow path is still located between the inlet and outlet such that pockets of fluid or air are not trapped in the pod pump. The grooves 1002 are included on both the liquid or fluid side and the air or drive side of the pod pumps 820, 828. In an embodiment, the grooves 1002 are also included in the mixing chamber 818 (see FIGS. 40A and 40B for the air or drive side of the pod pumps 820, 828 and the opposite side of the mixing chamber 818). In an alternative embodiment, the grooves 1002 are included only on one side of the pod pumps 820, 828 or not included at all.

[0164] In an alternative embodiment of the cassette, the liquid or fluid side of the pod pumps 820, 828 includes a feature (not shown) in which the inlet and outlet flow paths are continuous and a rigid outer ring (not shown) is molded around the pump chambers for further continuity. This feature maintains the seal formed with the septum (not shown). Figure 38E is a side view of the top plate 1100 in this embodiment.

[0165] An embodiment of the midplate 1200 is shown in Figures 39A and 39B. The midplate 1200 is further shown in Figures 37A-37F, which correspond to Figures 39A-39B. Accordingly, Figures 37A-37F show the location of the various valves and valve passages. Also shown is the location of the mixing chamber 818, as well as the location of the bulkheads (not shown) for each pod pump 820, 828.

[0166] FIG. 39A illustrates an embodiment of a cassette in which sensor elements are incorporated into the cassette to sense various properties of the fluid being pumped. In one embodiment, three sensor elements are included. However, in this embodiment, six sensor elements (two sets of three) are included. The sensor elements are provided in sensor cells 1314, 1316. In this embodiment, sensor cells 1314, 1316 are included as areas of the cassette for sensor elements. In one embodiment, the three sensor elements of two sensor cells 1314, 1316 are housed in sensor element housings 1308, 1310, 1312 and 1318, 1320, 1322, respectively. In one embodiment, two sensor element housings 1308, 1312 and 1318, 1320 house conductivity sensor elements and the third sensor element housing 1310, 1322 houses a temperature sensor element. The conductivity sensor element and temperature sensor element may be any conductivity or temperature sensor element known in the art. In one embodiment, the conductivity sensor is a graphite post. In another embodiment, the conductivity sensor element is made of stainless steel, titanium, platinum, or other metals that are coated for corrosion protection but still have electrical conductivity. The conductivity sensor element may include electrical wires that transmit the probe's information to a controller or other device. In one embodiment, the temperature sensor is a thermistor embedded in a stainless steel probe. However, in an alternative embodiment, a combination of temperature and conductivity sensor elements similar to those disclosed in U.S. Patent Application No. DEKA-024XX, filed October 12, 2007, and entitled "SENSOR INSTALLATION SYSTEM, APPARATUS AND METHOD" is used.

[0167] In alternative embodiments, no sensors on the cassette are used, only one temperature sensor is used, only one or more conductivity sensors are used, or one or more other types of sensors are used.

[0168] FIG. 39C is a side view of the mid-plate 1200 in this embodiment. FIGS. 40A and 40B show the bottom plate 1300. FIG. 40A shows the inside or inner surface of the bottom plate 1300. The inside or inner surface is the surface that contacts the bottom surface of the mid-plate (not shown). The bottom plate 1300 is attached to air or drive lines (not shown). Shown are the pod pumps 820, 828 in the mid-plate 1300 and corresponding inlet holes for air to drive the valves (not shown here, see FIGS. 37A-37F). Holes 810, 824 correspond to the first fluid inlet 810 and first fluid outlet 824 shown in FIG. 39B, respectively. Shown are the grooves 1002 for the pod pumps 820, 828 and the other flow paths of the corresponding halves of the mixing chamber 818. Also shown are the pump drive holes. Unlike the top plate, the corresponding bottom plate 1300 halves of the pod pumps 820, 828 and mixing chamber 818 clarify the distinction between the pod pumps 820, 828 and the mixing chamber 818. The pod pumps 820, 828 include air or drive channels in the bottom plate 1300, and the mixing chamber 818 has the same structure as the top plate half. The mixing chamber 818 does not include both a septum (not shown) and air or drive channels for mixing the liquids. Also shown are sensor cells 1314, 1316 with three sensor element housings 1308, 1310, 1312 and 1318, 1320, 1322.

[0169] Figure 40B shows drive ports 1306 on the outer bottom plate 1300 or on the outside of the bottom plate 1300. A drive source is connected to these drive ports 1306. There are no drive ports in the mixing chamber 818 since it is not air driven. Figure 40C is a side view of the bottom plate 1300 in an embodiment.

[0170] As discussed above, in various embodiments of the invention, one or more fluid circuits, such as a blood flow circuit, a balancing circuit, a directing circuit, and / or a mixing circuit, are provided in the cassette. Other cassettes, such as sensing cassettes, are disclosed in U.S. Patent Application Serial No. 12 / 038,474, entitled "Sensor Instrumentation Systems, Apparatuses and Methods," Docket No. F63, which is incorporated herein by reference in its entirety. In some embodiments, some or all of these circuits are combined in a single cassette. In alternative embodiments, these circuits are formed in each respective cassette. In still other embodiments, two or more fluid circuits are included in a single cassette. In some embodiments, two, three, or more cassettes are provided that are immovable relative to one another, and optionally communicate with one another. For example, in one embodiment, two cassettes are coupled by a pump, such as a pod pump as described above. The pod pump includes rigid chambers with a flexible partition dividing each chamber into a first side and a second side, each side being used for a different purpose as described above.

[0171] Examples of cassettes that may be used in the present invention are U.S. patent application Ser. No. 11 / 871,680, filed Oct. 12, 2007, and entitled "Pump Cassette," U.S. patent application Ser. No. 11 / 871,712, filed Oct. 12, 2007, and entitled "Pump Cassette," and U.S. patent application Ser. No. 11 / 871,787, filed Oct. 12, 2007, and entitled "Pump Cassette." No. 11 / 871,793, filed Oct. 12, 2007 and entitled "Pump Cassette," U.S. application Ser. No. 11 / 871,803, filed Oct. 12, 2007 and entitled "Cassette System Integration Apparatus," and U.S. patent application Ser. No. F62, filed Oct. 12, 2007 and entitled "Cassette System Integration Apparatus," each of which is incorporated herein in its entirety.

[0172] The cassette may further include various features such as pod pumps, fluid lines, valves, etc. The cassettes in the embodiments disclosed herein include various alternative embodiments. However, cassettes including similar functionality are contemplated. While the cassettes in the embodiments disclosed herein are implementations of the fluid designs shown, in alternative embodiments the cassettes may include various fluid paths and / or valve arrangements and / or pod pump arrangements and numbers, all of which are within the scope of the present invention.

[0173] In one embodiment, the cassette includes a top plate, a mid plate, and a bottom plate. There are various embodiments for each plate. Typically, the top plate includes the pump chambers and fluid lines, the mid plate includes the complementary fluid lines, metering pumps and valves, and the bottom plate includes the actuation chambers (and in embodiments, the top and bottom plates include complementary portions of the balance chambers or pod pumps).

[0174] Typically, the bulkhead is between the midplate and the bottom plate, but for balance chambers and pod pumps, a portion of the bulkhead is between the midplate and the top plate. In some embodiments, the bulkhead is attached to the cassette by overmolding, capture, adhesive, press fit, welding, or any other process or method, but in some embodiments, the bulkhead is separate from the top, mid, and bottom plates until the plates are assembled.

[0175] The cassette may be constructed from a variety of materials. Typically, in various embodiments, the materials used are solid and inflexible. In one embodiment, the plates are made from polysulfone, while in other embodiments the cassette may be made from other solid materials. In some embodiments, the plates are made from thermoplastic or thermosetting materials.

[0176] In one embodiment, the cassette is formed by placing bulkheads in precise locations (e.g., for one or more pod pumps, if present), assembling the plates in order, and connecting the plates. In one embodiment, the plates are connected using laser welding techniques. However, in other embodiments, the plates are glued, mechanically fastened, strapped together, ultrasonically welded, or connected using other methods of connecting the plates.

[0177] In embodiments, the cassette is used to pump various types of fluids from a source to a location, including nutrient and non-nutrient fluids, inorganic chemicals, organic chemicals, bodily fluids, or any other type of fluid. Additionally, in embodiments, the fluid includes a gas, and thus, in embodiments, the cassette is used to pump a gas.

[0178] The cassette functions to pump and direct fluid from a preferred location to a preferred location, however in some embodiments the outer pump pumps fluid into the cassette and the cassette pumps fluid out, however in some embodiments the pod pump functions to draw fluid into the cassette and pump fluid out of the cassette.

[0179] The flow paths are controlled by the position of the valves as described above. Thus, valves may be located in different positions or, in alternative embodiments, additional valves may be provided in the cassette. Additionally, the illustrated fluid lines and flow paths described above are only examples of fluid lines and flow paths. In alternative embodiments, more, fewer, and / or different flow paths may be provided. In further alternative embodiments, no valves are provided in the cassette.

[0180] The number of pod pumps (if present in the cassette) as described above may vary from embodiment to embodiment. For example, while various embodiments described above include two pod pumps, in other embodiments the cassette includes one pod pump. In further embodiments, the cassette includes more than one pod pump, or no pod pumps. The pod pump may be a single pump or multiple pod pumps ganged together to provide a continuous flow. Either or both cassettes may be used in various embodiments. However, as described above, in some embodiments, no pod pumps are present in the cassette or a pod pump is included between two or more cassettes. Examples of such systems are disclosed, without limitation, in U.S. patent application Ser. No. F62, entitled "Cassette System Integration Apparatus," which is incorporated herein by reference in its entirety.

[0181] The various fluid inlets and fluid outlets disclosed herein are fluid ports in the embodiments. Depending on the configuration and control of the valves in the implementation, the fluid inlets are fluid outlets. Thus, referring to the fluid ports as fluid inlets or fluid outlets is for descriptive purposes only. Interchangeable fluid ports are provided in various embodiments. Fluid ports are provided to impart specific flow paths to the cassette. These fluid ports do not necessarily all need to be used all of the time. Instead, the use of various fluid ports allows for flexibility in the implementation of the cassette.

[0182] Another example of a cassette is shown in FIG. 46, but is not limited thereto. FIG. 46A shows an integrally formed and assembled cassette system. Mixing cassette 500, middle cassette 600, and balancing cassette 700 are connected by fluid lines or conduits. Pods are provided between the cassettes. In FIG. 46B and FIG. 46C, various views are used to show the effect of the integrally formed cassette system. FIG. 50A, FIG. 50B, and FIG. 50C show fluid lines or conduits 1200, 1300, and 1400, respectively. Fluid flows between the cassettes through these fluid lines or conduits. FIG. 50A and FIG. 50B show that the larger fluid line or conduit 1300 and the smaller fluid line or conduit 1200 are check valves. In the embodiment, the check valves are duck hand valves, but in the alternative, any check valves can be used. 50C illustrates that fluid line or conduit 1400 is a fluid line or conduit that does not include a check valve. For purposes of description, the terms "fluid line" and "conduit" will be used interchangeably with respect to 1200, 1300, and 1400.

[0183] 46B and 46C, as well as FIG. 51A, illustrate the fluid flow through the various cassettes in one embodiment. For ease of description, the fluid flow begins with the mixing cassette 500. In FIGS. 46B and 51A, the fluid side of the mixing cassette 500 is illustrated. The fluid side includes a number of ports 8000, 8002, 8004, 8006, 8008, and 8010-8026, which are either fluid inlets or fluid outlets. In various embodiments, the one or more fluid inlets and fluid outlets include one or more fluid inlets for reverse osmosis ("RO") water 8004, bicarbonate, acid, and dialysate 8006. Additionally, the one or more fluid outlets, including drains, include at least one vent outlet as an outlet for the acid 8002 and the dialysate tank. In one embodiment, tubing (not shown) is provided behind the outlets and is the outlet (to prevent contamination). Additional outlets are further included for water, bicarbonate and water mixture, a dialysate mixture (bicarbonate plus acid and water).

[0184] The dialysate then flows from the mixing cassette 500 to a dialysate tank (not shown here, shown in FIG. 51A as 1502) and through conduits to the interior of the dialysate cassette 700 (outer dialysate cassette 600, pumped by pod pumps 602 and 604 (604 not shown here, shown in FIG. 46D and 46E). The flow paths within the cassette vary; therefore, the locations of the various inlets and outlets vary with the various cassette flow paths.

[0185] Figure 51B shows that in one embodiment of the cassette system, the conduit cell, conductivity sensor, and temperature sensor are contained in a separate cassette 1504 outside the cassette system shown in Figures 46A-46C. This outer sensor cassette 1504 is disclosed in U.S. patent application Ser. No. 12 / 038,474, entitled "SENSOR INSTALLATION SYSTEMS, APPARATUS AND METHODS," Docket No. F63, which is incorporated herein by reference in its entirety.

[0186] 51B shows the fluid flow path in this embodiment. In the mixing process for the dialysate in this embodiment, the bicarbonate mixture leaves the mixing cassette 500, flows to the outer sensor cassette, and then back to the mixing cassette 500 again. When the bicarbonate mixture reaches a predetermined threshold, acid is added to the bicarbonate mixture. The bicarbonate and acid are then mixed in the mixing chamber 506, and the dialysate flows from the cassette to the sensor cassette and back to the mixing cassette 500.

[0187] FIG. 46D shows that the mixing cassette 500 includes a pneumatic drive side. A number of valves and two pump chambers 8030, 8032 are provided in the cassette 500 in the area designated by reference numeral 500 to pump or meter the acid and bicarbonate. In some embodiments, additional metering pumps or fewer metering pumps are included. The metering pumps 8030, 8032 can be of any size required. In some embodiments, the pumps are different sizes relative to each other, while in other embodiments the pumps are the same size relative to each other. For example, in one embodiment, the acid pump is smaller than the bicarbonate pump. This is advantageous and effective when using high concentration acids. This is because it is desirable to use smaller pumps for accuracy and because it is preferable to use smaller pumps so that full strokes rather than partial strokes can be used for control.

[0188] Conduits 1200, 1300 include check valves. These conduits 1200, 1300 allow for one-way flow. In an embodiment, these conduits 1200, 1300 are all directed to drain. The location of these check valve conduits is clear from the flow path schematic in FIG. 51A. In the embodiment shown, fluid directed to drain passes through the mixing cassette 500. FIG. 46B shows that a fluid drain port 8006 is provided on the fluid side of the cassette 500.

[0189] After the dialysate is mixed and flows through the sensor cassette, shown in FIG. 51B at reference numeral 1504, it is determined whether the dialysate is within a predetermined parameter or threshold, and then the dialysate is pumped back into the mixing cassette 500, passes through the flat conduit 1400, is sent to the outer dialysate cassette 600, passes through the mixing cassette 500 through the check valve conduit 1200, and travels to the drain fluid outlet.

[0190] 46D and 46E show the various pods 502, 504, 506, 602, 604, 702, 704, 706, 708. Each of the pod housings is constructed similarly, however the interior of the pod housing differs depending on whether the pod is a pod pump 502, 506, 602, 604, 702, 704, a balance chamber pod 706, 708, or a mixing chamber pod 504.

[0191] 51A and 51B, as well as 46D and 46E, show the various pods provided in both the fluid flow path and the cassette system. Pod 502 is the water pod pump and 504 is the bicarbonate water pod pump (which pumps water to bicarbonate) of the mixing cassette 500. Pod 506 is the mixing chamber. Once the dialysate is mixed in the mixing chamber 506, it flows from the mixing cassette 500 to the sensor cassette 1504 which determines if the dialysate is acceptable or not and the dialysate flows through the mixing cassette dialysate tank outlet to the dialysate tank 1502. However, if the dialysate is determined to be unacceptable, the fluid is returned to the fluid cassette 500 and pumped through conduit 1400 to the outer dialysate cassette 600, through check valve conduit 1200, through the mixing cassette 500 and out the drain outlet.

[0192] 46A-46C, along with FIGS. 51A and 51B, show the outer dialysate cassette 600 between the mixing cassette 500 and the inner dialysate cassette 700. The pod pumps 602, 604 pump dialysate from the dialysate tank 1502 and into the balance chambers 706, 708 of the inner dialysate cassette 700 (the motive force of the dialysate). The outer dialysate cassette 600 pushes dialysate into the inner dialysate cassette (i.e., the pump of the inner dialysate cassette 700 does not pump dialysate). Thus, dialysate from the outer dialysate cassette 600 is pumped from the dialysate tank 1502 through the heater 1506, through the ultrafiltration membrane 1508, and into the inner dialysate cassette 700.

[0193] 51A-51B, as well as 46D-E, show that the inner dialysate cassette 700 includes a metering pod 8038 (i.e., an ultrafiltration metering pod), balancing pods 706, 708, and pod pumps 702, 704. The inner dialysate cassette 700 further includes fluid outlets and fluid inlets. These inlets and outlets include an outlet to the dialyzer 1510, an inlet from the dialyzer 1510, and a dialysate inlet (the ultrafiltration membrane 1508 connects to a port on the inner dialysate cassette). Fluid inlets and outlets are further included for DCA and DCV connections for priming and disinfection. Various conduits (1200, 1300, 1400) function to allow fluid flow to communicate between the cassettes 500, 600, 700 and to allow fluid flow to drain through the mixing cassette 500. The largest check valve 1300 (also shown in FIG. 50B) is used during disinfection. This tube is oversized to accommodate blood clots and other contaminants that flow through the waterway during disinfection in the preferred embodiment.

[0194] In an embodiment, the valves and pumps of the cassette system are pneumatically actuated. A separate pneumatic source is attached to the cassette by a separate tube. Thus, each pump, balancing pod, or valve is individually connected to a pneumatic actuation manifold (not shown). Figures 52A-52F show that in an embodiment, the tubes are connected to at least one block 1600. In an embodiment, multiple blocks are used to connect the various tubes. Block 1600 is dropped into the manifold and then suitably connected to a pneumatic actuator. This allows the pneumatic tubes to be easily connected to the manifold.

[0195] 46D further illustrates that in one embodiment, the cassette system includes a spring 8034 to assist in holding the system together. The spring 8034 is hooked to the mixing cassette 500 and the inner dialysate cassette 700 by a grabber 8036. However, in alternative embodiments, other means or devices may be used to assist in maintaining the appropriate system in a preferred orientation, including, but not limited to, latching means, resilient means, etc.

[0196] An example pod is shown in Figures 47A-47C. The pod includes two fluid ports 902, 904 (inlet and outlet), and the pod can be assembled differently in various embodiments. Various embodiments of the structure are disclosed, but are not limited to, in U.S. patent application Ser. No. 11 / 787,212, Docket No. E78, filed Apr. 13, 2007, and entitled "Fluid Pumping Systems, Apparatus and Methods," which is incorporated herein by reference in its entirety.

[0197] Figures 47A, 47D and 47E show a chamber groove 906. A groove 906 is included in each half of the pod housing. In other embodiments, the groove is not included, and in some embodiments, the groove is included in only one half of the pod housing.

[0198] Figures 48A and 48B show an embodiment of a membrane that may be used in pod pumps 502, 504, 602, 604, 702, and 704. This membrane is described above in Figure 5A. In another embodiment, the membrane shown in Figures 5B-5D may be used. Figure 49 is an exploded view of an embodiment of a pod pump.

[0199] In various embodiments of the invention, one or more "pod pumps" are used for various purposes. The structure of the pod pump is described above and below. This structure can be modified for various uses such as a pump, balancing chamber, mixing chamber, etc. Additionally, the pod pump can be located anywhere in the system, such as in a cassette or between two or more cassettes.

[0200] Typically, the pod pump includes a rigid chamber (e.g., having a suitable shape, such as spherical, elliptical, etc.), and the pod pump includes a flexible partition dividing each chamber into a first half and a second half. In some embodiments, the rigid chamber is spheroidal. As used herein, the term "spheroidal" refers to a three-dimensional shape that corresponds to an ellipse rotated about one of its major, major, and minor axes, and typically includes three-dimensional ovals, oblate and prolate spheroids, spheres, and shapes generally similar thereto.

[0201] Each half of the pod pump has at least one inlet valve and usually (but not necessarily) at least one outlet valve (in some embodiments the same port is used for both inlet and outlet). For example, the valves may be on-off valves or two-way proportional valves. For example, the valves on one side of the chamber may be two-way proportional valves, one connected to a high pressure source and the other connected to a low pressure (or vacuum) sink. The valves on the other half may be opened or closed to direct the fluid.

[0202] In some embodiments, the septum has a variety of cross-sectional thicknesses. Thinner, thicker, or variable thickness septums may be used to accommodate the stiffness, flexibility, and other properties of the selected septum material. Thinner, thicker, or variable thickness septum wall thicknesses may be used to control the septum to promote flexing in certain areas relative to other areas, thereby aiding in pumping action and control of the primary fluid flow in the pump chamber. In this embodiment, the septum is shown with the thickest cross-sectional area closest to the center. However, in other embodiments, septums having various cross-sections may be provided, with the thickest and thinnest areas located anywhere on the septum. Thus, for example, thinner cross-sections may be located near the center and thicker cross-sections may be located near the periphery of the septum. In one embodiment, the septum has at least one section of a tangential slope, while in other embodiments the septum is completely smooth or substantially smooth.

[0203] The septum is made of a material that has desirable durability and is flexible to be compatible with the fluid. The septum is made of a material that flexes in response to fluid, liquid or gas pressure or vacuum acting on the actuation chamber. The septum material is further selected to be biocompatible, temperature compatible, and compatible with the various primary fluids that are pumped by the septum or introduced into the chamber to facilitate movement of the septum. In one embodiment, the septum is made of high elongation silicone. However, in other embodiments, the septum may be made of elastomers or rubbers, including, but not limited to, silicone, urethane, nitrile, EPDM, or other rubber, elastomeric, or flexible materials.

[0204] The shape of the septum is dependent on a variety of conditions, including, but not limited to, the shape of the chamber, the dimensions of the chamber, the characteristics of the primary fluid, the volume of the primary fluid pumped per stroke, and the means and mode of attachment of the septum to the housing. The dimensions of the septum are dependent on a variety of conditions, including, but not limited to, the shape of the chamber, the dimensions of the chamber, the characteristics of the primary fluid, the volume of the primary fluid pumped per stroke, and the means and mode of attachment of the septum to the housing. Thus, the shape and dimensions of the septum will vary in various embodiments depending on these and other conditions.

[0205] The septum may be of any thickness. However, in embodiments, the thickness ranges between 0.002 inches and 0.125 inches (1 inch = 2.54 cm). The preferred thickness varies depending on the material used for the septum. In one embodiment, high elongation silicone is used at a thickness of 0.015 inches to 0.050 inches (0.0381 cm to 0.127 cm). However, in other embodiments, the thickness varies.

[0206] In some embodiments, the septum is preformed to include a generally dome-shaped configuration over at least a portion of the area of ​​the septum, and the dimensions of the dome may vary based on some or more of the factors discussed above, however, in other embodiments, the septum does not include a preformed dome shape.

[0207] In some embodiments, the dome of the septum is formed using fluid injection molding. However, in other embodiments, the dome can be formed using compression molding. In alternative embodiments, the septum is generally flat. In other embodiments, the size, width, or height of the dome varies.

[0208] In various embodiments, the septum is retained by various means and methods. In one embodiment, the septum is clamped between portions of the cassette. In an embodiment, the edges of the cassette include features that grip the septum. In another embodiment, the septum is clamped to the cassette using at least one bolt or other device. In another embodiment, the septum is overmolded with a piece of plastic, which is welded or glued to the cassette. In another embodiment, the septum is sandwiched between a mid plate and a bottom plate. Although embodiments have been disclosed that attach the septum to the cassette, other methods and means for attaching the septum to the cassette may be used. In an alternative embodiment, the septum is attached directly to a portion of the cassette. In an embodiment, the septum has a thickness at the end compared to other areas, and the septum is sandwiched by the plates. In an embodiment, the thicker area is a gasket, in an embodiment, an O-ring, ring, or other shaped gasket.

[0209] In some embodiments, the gasket is continuous with the bulkhead. However, in other embodiments, the gasket is a separate part from the bulkhead. In some embodiments, the gasket is formed from the same material as the bulkhead. However, in other embodiments, the gasket is formed from a separate material from the bulkhead. In some embodiments, the gasket is formed by over-molding a ring around the bulkhead. The gasket can be any shape ring or suitable seal to complement the pod pump housing in some embodiments. In some embodiments, the gasket is a compression type gasket.

[0210] Due to the rigid chambers, pod pumps typically have a fixed volume. However, within the pod pump, the first and second compartments have different volumes due to the location of the flexible partition that separates the chambers. Forcing fluid into one compartment will displace fluid in the other compartment of the chamber. However, the fluids do not directly contact each other within the pod pump, typically due to the flexible partition.

[0211] Thus, in one embodiment, a pod pump used for pumping is configured to receive a control fluid in the first compartment and a fluid to be pumped in the second compartment. The control fluid may be a fluid, i.e., a liquid or a gas. In one embodiment, the control fluid is air. By forcing the control fluid out of the pod pump (e.g., by a vacuum or at least a pressure lower than the pressure within the pod pump), the pod pump draws fluid (e.g., blood, dialysate, etc.) into the other compartment of the pod pump. Similarly, by forcing control fluid into the pod pump (e.g., from a high pressure source), the pod pump expels the fluid. Further, by controlling the valve of the second compartment, the fluid is transported through the first valve and expelled through the second valve by the action of the control fluid.

[0212] Alternatively, pod pumps may be used to balance fluids, such as dialysate, as described above. In such cases, instead of a control fluid, a fluid is directed to each compartment of the pod pump. As described above, the volume of the pod pump is typically fixed by a rigid chamber. Thus, when a first volume of fluid is pumped into a first compartment of the balancing pod, an equal volume of fluid is expelled from a second compartment of the balancing pod (assuming that the fluid is typically incompressible under pod actuation conditions). Thus, equal volumes of fluid can be moved using the balancing pod. For example, in FIG. 5, the balancing pod allows fresh dialysate to enter the first compartment and used dialysate to enter the second compartment. The flows of fresh and used dialysate volumes are balanced with each other.

[0213] In some embodiments, a pod pump is used that does not include a flexible partition separating the chambers. In the above examples, the pod pump can be used as a mixing chamber. For example, mixing chamber 189 in FIG. 7A is such a pod pump.

[0214] A non-limiting example of a pod pump is shown in FIG. 9. This figure is a cross-sectional view of a pneumatically controlled valve used in an embodiment of a cassette. As used herein, the term "pneumatic" refers to the use of air or other gas to move a flexible diaphragm or other member (the use of air is merely exemplary, and other control fluids such as nitrogen (N2), carbon dioxide, water, oil, etc. are used in other embodiments). Three rigid portions are used for a "top" plate 91, a mid-plate 92, and a "bottom" plate (the terms "top" and "bottom" are only used to indicate the orientation shown in FIG. 9; the valve may be oriented in any direction in practice). The top and bottom plates 91 and 93 are flat on both sides, while the mid-plate 92 is provided with channels, indentations, and holes to form various flow paths, chambers, and ports. The diaphragm 90 forms a valve chamber 97 along with the mid-plate 92. Air pressure is applied through air port 96 such that positive gas pressure forces diaphragm 90 against valve seat 99, closing the valve, or negative gas pressure pulls the diaphragm away from the valve seat, opening the valve. A controlled gas chamber 98 is formed by diaphragm 90, top plate 91, and mid-plate 92. Mid-plate 92 includes an indentation into which diaphragm 90 rests, thereby forming controlled gas chamber 98 on one side of the diaphragm and valve chamber 97 on the opposite side.

[0215] Air ports 96 are formed by channels formed by the "top" surface of mid-plate 92 with top plate 91. By providing communication between multiple valve chambers of the cassette, the valves are ganged so that all ganged valves are opened and closed simultaneously by one source of air pressure. Channels formed in the "bottom" surface of mid-plate 92 with the bottom plate form valve inlets 94 and valve outlets 95. Holes formed through mid-plate 92 provide communication between inlets 94 and valve chambers 97 (through valve seats 99) and between the valve chambers and outlets 95.

[0216] The septum 90 is provided with a thickened edge 88 that fits tightly into a groove 89 in the midplate 92. The septum 90 is thus positioned in and retained by the groove 88 prior to the top plate 91 being ultrasonically welded to the midplate 92. The septum therefore does not interfere with the ultrasonic welding of the two plates. The septum does not depend on the two plates being ultrasonically joined precisely in place. The valve is therefore easily manufactured without the need for very tight ultrasonic welding. As shown in FIG. 9, the top plate 91 includes additional material that extends into the controlled gas chamber 98, which prevents the septum from moving too far away from the groove 89 and prevents the thickened edge 88 of the septum from exiting the groove 89.

[0217] A pressure sensor is used to monitor the pressure in the pod. For example, by alternately applying air pressure to the air side of the chamber, the diaphragm cycles back and forth across the total chamber volume. With each cycle, air pressure applies a vacuum to the pod, causing fluid to be pumped through the upstream valve of the inlet fluid port. Air pressure applies a positive pressure to the pod, causing fluid to be expelled through the outlet port and downstream valve.

[0218] FIG. 10 is a cross-sectional view of an embodiment of a pod pump that is incorporated into an embodiment of a fluid-control cassette. In an embodiment, the cassette incorporates a plurality of pod pumps and a plurality of valves formed by the techniques of construction shown in FIGS. 9 and 10. In the above embodiment, the pod pump of FIG. 10 is formed from different portions of the same three rigid portions used to form the valve of FIG. 9. These rigid portions are a "top" plate 91, a mid plate 92, and a "bottom" plate (as noted above, the terms "top" and "bottom" only refer to the orientation shown in FIG. 9). To form the pod pump, the top plate 91 and the bottom plate 93 include generally hemispherical portions that together form a hemispherical pod pump.

[0219] A diaphragm 109 separates the central cavity of the pod pump into a chamber that receives the fluid to be pumped (the pump chamber) and another chamber that receives a control gas that pneumatically drives the pump (the drive chamber). An inlet 94 allows fluid to enter the pump chamber and an outlet allows fluid to leave the pump chamber. The inlet 94 and outlet 95 are formed between the midplate 92 and the bottom plate 93. Air pressure is applied through air ports 106 to the diaphragm 109 against one wall of the pod pump cavity with positive gas pressure to minimize the pump chamber volume as shown in FIG. 10, or to the diaphragm against the other wall of the pod pump cavity with negative gas pressure to maximize the pump chamber volume.

[0220] In some embodiments, the pod pump may use a variety of structures including grooves in one or more plates exposed to the pod pump cavity, among other things, to prevent the bulkhead from blocking the inlet and / or outlet flow paths for fluid and / or air.

[0221] The septum 109 is formed with a lip 88 with a thickness which is firmly held in the groove 89 in the mid-plate 92. Thus, like the valve chamber of FIG. 9, the septum 109 is positioned in and held by the groove 89 prior to the top plate 91 being ultrasonically welded to the mid-plate 92. Thus, the septum does not interfere with the ultrasonic welding of the two plates. The septum is not dependent on the two plates being ultrasonically joined precisely in place. Thus, the valve is easily manufactured without the need for ultrasonic welding to be very tight.

[0222] Figure 11A is a schematic diagram showing, in an embodiment, a pressure actuation system 110 for a pod pump such as that shown in Figure 10. In this embodiment, air is used as the control fluid (e.g., the pump is pneumatically actuated). As mentioned above, in alternative embodiments, other fluids (e.g., water) are used as the control fluid.

[0223] 11A, pressure actuation system 110 applies alternating positive and negative pressure to gas in actuation chamber 112 of pod pump 101. Pneumatic actuation system 110 includes actuation chamber pressure transducer 114, variable positive supply valve 117, variable negative supply valve 118, positive pressure gas tank 121, negative pressure gas tank 122, positive pressure tank pressure transducer 115, negative pressure tank pressure transducer 116, as well as electronic controller 119.

[0224] The positive pressure tank 121 applies a positive pressure of control gas to the drive chamber 112, pushing and moving the partition 109 to a position where the pump chamber 111 has the minimum volume (i.e., the position where the partition is against the wall of the pump chamber where it is solid). The negative pressure tank 122 applies a negative pressure of control gas to the drive chamber 112, pushing and moving the partition 109 in the opposite direction to a position where the pump chamber 111 has the maximum volume (i.e., the position where the partition is against the wall of the drive chamber where it is solid).

[0225] In this example, a valve system is used to control the communication between each of these tanks 121, 122 and the actuation chamber 112. In FIG. 11A, a separate valve is used for each tank. A positive supply valve 117 controls the communication between the positive pressure tank 121 and the actuation chamber 112, and a negative supply valve 118 controls the communication between the negative pressure tank 122 and the actuation chamber 112. These two valves are controlled by an electronic controller 119 (alternatively, a single three-way valve is used instead of the two separate valves 117, 118). In an embodiment, the positive supply valve 117 and the negative supply valve 118 are variable restriction valves as opposed to two-way on-off valves. The advantages of using variable valves are discussed below.

[0226] 11A shows that the controller 119 also receives pressure information from three pressure transducers: actuation chamber pressure transducer 114, positive pressure tank pressure transducer 115, and negative pressure tank pressure transducer 116. As the names suggest, these transducers measure the pressure in the actuation chamber 112, positive pressure tank 121, and negative pressure tank 122, respectively. The controller 119 monitors the pressure in the two tanks 121, 122 to ensure that they are appropriately pressurized (positively or negatively). Compressor type pumps or pumps are used to obtain the appropriate pressures in these tanks 121, 122.

[0227] In one embodiment, the pressure exerted by the positive pressure tank 121 is strong enough to press the septum 109 against the rigid pump chamber wall under normal conditions. Similarly, the negative pressure (i.e., vacuum) exerted by the negative pressure tank 122 is strong enough to press the septum against the rigid actuation chamber wall under normal conditions. However, in one embodiment, these positive and negative pressures provided by the tanks 121, 122 are well within safe limits, which are the same pressures that would open either the positive supply valve 117 or the negative supply valve 118, and the positive and negative pressures exerted against the septum 109 are not strong enough to cause harm to the patient.

[0228] In one embodiment, the controller 119 monitors pressure information from the actuation chamber pressure transducer 114 and, based on this information, controls the valve mechanism (valves 117, 118) to move the diaphragm 109 to a position of minimum pump chamber volume and, once in this position, retracts the diaphragm 109 to a position of maximum pump chamber volume.

[0229] The pressure actuation system (including actuation chamber pressure transducer 114, positive pressure tank pressure transducer 115, negative pressure tank pressure transducer 116, variable positive supply valve 117, variable negative supply valve 118, controller 119, positive pressure gas tank 121, and negative pressure gas tank 122) is located entirely or substantially outside the insulated volume shown at 61 in Figure 6. In an embodiment, the components that come into contact with the blood and / or dialysate (i.e., pod pump 101, inlet valve 105, and outlet valve 107) are located in the insulated volume so that they can be more easily sanitized.

[0230] FIG. 11B illustrates another example of a pressure actuation system 110 for a pod pump. In this example, pod pump 101 includes pump chamber 111, actuation chamber 112, and a diaphragm 109 dividing the two sides. Fluid ports 102 and 104 allow access to fluid into and out of pump chamber 111 using fluid valves (not shown). However, in pod pump 101, fluid ports 102 and 104 include "volcano" ports 126, which typically have a raised shape, such that when diaphragm 109 contacts the port, it tightly seals the port. FIG. 11B also illustrates a three-way valve connecting pressure tanks 121, 122. Three-way valve 123 communicates with actuation chamber 112 through one port in this example.

[0231] It should be noted that Figures 11A and 11B show that instead of the two tank pneumatic drive system, other types of drive systems can be used to move the bulkhead back and forth.

[0232] As mentioned above, the positive supply valve 117 and the negative supply valve 118 of the air actuation system 110 of FIG. 11A are preferably variable restriction valves as opposed to two-way on-off valves. With the use of variable valves, the pressure applied to the actuation chamber 112 and diaphragm 109 can be easily controlled by a small amount of pressure in the tanks 121, 122 instead of applying full tank pressure to the diaphragm. Thus, the same tank or set of tanks can be used for different pod pumps, even though the pressures to drive the pod pumps are different for the pod pumps. One pod pump can be driven by half the tank pressure, while another pod pump is driven by the same tank but at a quarter tank pressure, even though the different pods of the dialysis system are designed to operate at different pressures, but all share the same tank or set of tanks, but are driven at different pressures using various valves. The pressure used in the pod pump varies in response to conditions that arise or change during the dialysis process: if the tubing of the system becomes compressed, for example due to the tubing becoming distorted, the positive and / or negative pressure used in the pod pump will be increased to compensate for the increased restriction.

[0233] FIG. 12 is a graph showing how pressure applied to a pod pump is controlled using a variable valve. The vertical axis indicates the pressure in the positive and negative tanks (121 and 122 in FIG. 11A), respectively, using PR+ and PR-. PC+ and PC- indicate the positive and negative control pressures acting on the pod pump bulkhead, respectively. A positive pressure is applied to the actuation chamber (to force fluid out of the pump chamber) from time T0 to approximately time T1 as shown in FIG. 12. By repeatedly increasing and decreasing the flow restriction by the positive variable valve (117 in FIG. 11A), the pressure applied to the actuation chamber is maintained at approximately the desired positive control pressure PC+. The pressure varies in a sinusoidal pattern around the desired control pressure. An actuating chamber pressure transducer (114 in FIG. 11A) in communication with the actuating chamber measures the pressure in the actuating chamber and transmits the pressure measurement information to a controller (119 in FIG. 11A) which controls the variable valve such that the actuating chamber pressure varies around the desired control pressure PC+. In the absence of a fault condition, the diaphragm presses against the solid wall of the pumping chamber, thereby completing the stroke. The controller determines that the end of stroke has been reached when the pressure measured in the actuating chamber does not drop as the restriction created by the variable valve decreases. In FIG. 12, the end of the discharge stroke occurs around time T1. Once the end of stroke is detected, the controller closes the variable valve completely so that the actuating chamber pressure does not increase above the desired control pressure PC+.

[0234] After the positive variable valve closes, the negative variable valve (118 in FIG. 11A) is partially opened and the negative pressure tank draws gas from the actuation chamber and fluid into the pump chamber. Negative pressure is applied to the actuation chamber from a time shortly after T1 to a time T2 as shown in FIG. 12. As with the exhaust (positive pressure), the above-mentioned stroke can be maintained at approximately the desired negative control pressure PC- (less than the pressure of the negative pressure tank) by repeatedly increasing and decreasing the flow restriction caused by the variable valve. The pressure varies in a sinusoidal pattern around the desired control pressure. The pressure transducer in the actuation chamber sends pressure measurement information to the controller, which controls the variable valve to vary the actuation chamber pressure around the desired control pressure PC-. If there is no fault condition, the diaphragm is pulled against the solid wall of the actuation chamber, thereby completing the tension (negative pressure) stroke. As discussed above, the controller determines that the end of stroke has been reached when the partial vacuum measured in the actuation chamber does not drop as the restriction created by the variable valve decreases. In FIG. 12, the end of the draw stroke occurs at about time T2. When the end of stroke is detected, the controller fully closes the variable valve so that the actuation chamber vacuum does not rise above the desired negative control pressure PC-. Once the draw stroke is complete, the positive variable valve partially opens to initiate a new exhaust stroke with positive pressure.

[0235] Thus, each pod pump in this example uses two variable aperture valves to throttle flow from a positive pressure source to a negative pressure. The pressure in the actuation chamber is monitored and the controller uses this pressure measurement to determine the appropriate command for both of the valves to obtain the desired pressure in the actuation chamber. The advantages of this configuration are that the fill and deliver pressures are precisely controlled to obtain the desired flow rate while respecting pressure limits, and that the pressure varies with a small sinusoidal signature command. This signature is monitored to determine when the pump is at the end of a stroke.

[0236] Another advantage of using a variable valve instead of a two-way valve as described above is that by only partially opening and closing the variable valve, less wear is caused to the valve, as repeated "hard" opening and closing of the two-way valve shortens the valve's lifespan.

[0237] The end of the stroke is detected and the integrated value of the correlation function is very small, indicating that the stroke was blocked and not completed. By identifying the fill stroke or the transfer stroke, downstream blockages can be distinguished from upstream blockages (this is difficult for blockages that occur near the end of the stroke when the septum is located close to the wall of the chamber). Figures 13A and 13B show the detection of a blockage (the chamber pressure drops to zero when a blockage is detected).

[0238] Under normal operation, the integrated value of the correlation function increases as the stroke progresses. If this value remains small or does not increase (in the case of very low impedance flow or blockages), the stroke is either too short or due to a valve failure or a faulty pressure signal the actual pressure does not follow the desired sinusoidal pressure pattern. The lack of correlation is detected and used in error handling in these cases.

[0239] When the flow controller is running under normal circumstances, the control loop adjusts the pressure in response to changes in fluid velocity. If the impedance of the circuit increases dramatically and the pressure limit saturates before the flow has a chance to reach the desired rate, the flow controller cannot adjust the pressure higher to reach the desired fluid velocity. These conditions occur when a blood clot forms in the circuit or when a line becomes partially occluded. These are used in error handling when pressure saturation is detected when the flow does not reach the desired flow rate.

[0240] If there is a valve or pneumatic problem, such as a leaking fluid valve or noise in the pressure signal, the ripple will continue indefinitely on the stroke and the end-of-stroke algorithm will not see enough change in the pressure ripple to detect the end of the stroke. Therefore a safety check is added to detect if the stroke is completed more than necessary. This information can be used for error handling.

[0241] In a dual pump, such as pump 13 shown in Figure 3A, the two pump chambers cycle in opposite directions, affecting the pump period. A phase relationship from 0° (both chambers work in the same direction) to 180° (chambers work in opposite directions) can be selected. The phase movement can be varied in the embodiment since it is not possible to move both chambers in the same direction at the same time. If they were to move at the same time, both the inlet and outlet valves would be open and the end of stroke would not be properly detected.

[0242] By selecting a phase relationship of 180°, continuous flow into and out of the pod occurs. This is the nominal pump mode when continuous flow is required. Setting a phase relationship of 0° is useful for single needle flow. The pod is first filled with the needle and then delivered to the same needle. Driving at a phase between 0° and 180° can be used to obtain a tension relationship across the dialyzer (hemodiafiltration or continuous backflush). Figures 8A-8C show graphical representations of the above phase relationships.

[0243] The pod pump controls the flow of fluid through various subsystems. For example, a sinusoidal pressure waveform is added to the DC pressure command that constitutes the commanded pressure signal for the pod pump. When the diaphragm is moving, the pod pressure tracks the sinusoidal command. When the diaphragm contacts the chamber wall and stops moving, the pod pressure is held constant and does not track the sinusoidal input command. The difference in the pod's subsequent pressure signal commands is used to detect the end of the stroke. From the end of stroke information, the time of each stroke is calculated. By knowing the volume of the pod and when it completes a stroke, the flow rate for each pod is determined. The flow rate is fed back to a PI loop to calculate the required DC pressure for the next stroke.

[0244] The magnitude of the sine wave input is selected to be large enough relative to the actual pressure to adequately track the command, and small enough that when subtracted from the DC pump pressure and applied to the pod the pressure is sufficient to cause the diaphragm to move under the expected operating conditions of fluid viscosity, head height and circuit resistance. The frequency of the sine wave input is empirically selected to ensure end of stroke detection. The more periods of the sine wave per stroke, the more accurate the end of stroke detection algorithm will be.

[0245] To detect subsequent command changes in pod pressure, the pod pressure signal is sent through a cross-correlation filter. The size of the sampling window for the cross-correlation filter is equal to the period of the input sine wave. For every sample in the window, the command pressure signal is multiplied by the previous sample of actual pressure and added to the previous correlation value. The window is moved by one frame and the process is repeated. The result is discriminated and passed through a second order filter with a corner frequency similar to the frequency of the input sine wave and a damping ratio of 1. The effect of this filter is to act as a band pass filter that separates signals that are correlated at the frequency of the input sine wave. The absolute value of the output of this filter is passed through a second order low pass filter with a frequency equal to the sine wave frequency and a damping ratio of 3.0. This second order filter is used to combine the discriminated signal and the resultant signal and to reduce noise in the resultant signal. If the two signals are correlated, the value passing through the resultant filter will be large. If the two signals are uncorrelated (e.g. at the end of a stroke), the value passing through the resultant filter will be small. The end of stroke can be detected when the filtered cross-correlation signal falls below a predefined threshold or drops to 1 percent of its maximum value over the stroke. This threshold or percent drop can be varied as a function of pressure and flow rate to tune performance for a given pump scenario.

[0246] The end of stroke algorithm takes approximately one period of the sine ripple to detect the end of stroke, so by minimizing this period (maximizing the amplitude of the sine wave) the delay at the end of stroke is reduced. Low pressure, high pressure flows are not well tracked by the controller. Low pressure strokes tend to have low fluid velocities, so the end of stroke delay is a small percentage of the total stroke time. Thus the frequency is low for low pressure strokes. The frequency of the sine wave can be adjusted as a linear function of the delivery pressure. This ensures that the delay is minimal when the stroke is shortest. If the frequency of the sine wave for the preferred pressure is changed, the filter for the cross correlation function needs to be adjusted further. The filter is set to continuously calculate the filter coefficients based on this changing frequency.

[0247] The pod chamber pressure is further controlled using two variable solenoid valves: one connects the plenum to a higher pressure source, and the second connects the plenum to a low pressure (or vacuum) sink. Solenoid valves tend to have large neutral zone areas, so a non-linear offset term is added to the controller to compensate.

[0248] FIG. 14 shows an example of a control algorithm. The controller in this example is a standard discrete PI regulator. The output of the PI regulator is split into two paths, one for the source valve and the other to the sink valve. An offset term is added to each of these paths to compensate for the neutral zone of the valve. The resulting command is limited to valves greater than zero (after being inverted in the case of the sink valve).

[0249] The offset terms are negative for the source valve and positive for the sink valve, so both valves actuate even if the error is zero. These offsets improve the trajectory following and disturbance rejection performance of the controller, but also cause both valves to leak at steady state when the command offset is slightly larger than the neutral zone of the actual valve. In this case the valves have equal and opposite leakage mass flows at steady state.

[0250] To eliminate this leakage mass flow while the control system is idle, a "power saving" block is added to shut off the valve if the absolute value of the error term remains small for a certain period of time, similar to the use of a mechanical brake on a servo motor.

[0251] As shown in FIG. 15, the controller in this example uses a standard isolated PI regulator. The circuit of the PI regulator is shown. The integrator can be limited to prevent windup when the command saturates. The integrator is always allowed to unwind. The amount of air in the pod is different for the fill stroke and the deliver stroke, so the response of the pod will be very different for the fill stroke and the deliver stroke. The proportional gain is adjusted differently for the deliver stroke and the fill stroke to better adjust for the different pod responses.

[0252] The PI regulator saturation limit should be determined taking into account the offset value that is added as a result. For example, if a valve saturates at 12 V and a fixed offset of 5 V is added after the PI loop, the PI loop saturation limit should be set to 7 V. The different positive and negative saturation limits are due to different dead bands in the upstream and downstream valves.

[0253] During the fill stroke, the upstream fluid valve is closed and the downstream fluid valve is open, allowing fluid to enter the chamber. During the delivery stroke, the upstream fluid valve is open and the downstream fluid valve is closed, allowing fluid to exit the chamber. Between the end of one stroke and the start of the other stroke, both fluid valves are closed.

[0254] As noted in certain embodiments, the pod pumps may be powered by a control fluid, such as air, nitrogen, water, oil, etc. The control fluid is selected to be relatively incompressible and, in some cases, relatively inexpensive and / or non-toxic. The control fluid is delivered to the pumps of the system using a series of tubes or other suitable conduits. A controller controls the flow of the control fluid within the tubes or conduits. In some embodiments, the control fluid is held at different pressures within the tubes or conduits. For example, some of the control fluid is held at positive pressure (i.e., above atmospheric pressure), some at negative pressure (below atmospheric pressure), or even at zero pressure (i.e., vacuum). As shown in FIG. 11A, the pod pumps are controlled by a control fluid that is operated by a controller. As previously described, the controller (119) opens and closes valves (e.g., valves 117 and 118) at different times during a pump cycle to expose the pneumatic side of the pod pump to positive pressure (121) or vacuum (122).

[0255] In a further specific embodiment, the controller is isolated from the various fluid circuits (usually electronic) and there is no electrical contact between the controller and the fluid circuits, but a controlled fluid (e.g., air) is arranged to flow between the controller and the various pumps. This arrangement has advantages such as ease of maintenance (the controller and the various circuits can be serviced separately). In one embodiment, the fluid circuits are kept isolated by an insulating barrier (e.g., a "fire wall") or the like, such that the controller is not exposed to harsh conditions when heated to a disinfecting temperature or exposed to relatively high temperatures or harsh conditions (e.g., radiation) that are effective for disinfection.

[0256] Thus, in one embodiment, the system has a "cold" section (not heated) and a "hot" section that is partially heated for disinfection. The "cold" section is insulated from the "hot" section by an insulating material. In one embodiment, the insulating material can be obtained by forming a foamed material in a mold, but it is also possible to form the insulating material by spraying, or even by cutting a sheet material.

[0257] In an embodiment, the "hot" section is heated to a relatively high temperature. For example, the "hot" section is heated to a temperature sufficient to sterilize the components within the "hot" section. Many electronic components degrade other functions when heated above 50°C, so it is beneficial to separate the electronic components from other components to be sterilized. Thus, components that may need to be sterilized at times are kept in the "hot" section, and components that cannot be heated to such temperatures are kept in the "cold" section. In one embodiment, the "cold" section includes a circulation system, such as a fan or grid, that allows air to flow in and out of the cold box.

[0258] The "hot" section may be fully or partially covered with insulation. In some embodiments, the insulation extends to cover access points to the "hot" section, such as doors, ports, gaskets, etc. For example, when the "hot" section is sealed, the insulation completely covers the "hot" section.

[0259] Examples of components that are in the "cold" section include power supplies, electronic components, power lines, air control components, etc. In some embodiments, at least some of the fluids entering or leaving the "hot" section pass through the "cold" section, although in other embodiments, the fluids pass only through the "hot" section without passing through the "cold" section.

[0260] Examples of components within the "hot" section include cassettes, fluid lines, etc. In an embodiment, several electrical components are provided in the "hot" section. These include a heater, which heats the hot box itself in addition to the fluid (see heater 72 in FIG. 3A). In another embodiment, the heater heats the entire "hot" section to the desired temperature.

[0261] In one embodiment, the "hot" section includes some or all of the fluid lines. Additionally, the "hot" section may include temperature sensors, conductivity sensors, blood leak sensors, heaters, other sensors, switches, emergency lights, etc.

[0262] In one embodiment, the manifold for air or other control fluid is moved to the "hot" section from the "cold" section. Separating the components into "hot" and "cold" sections has several advantages, including the lifespan, reliability, or efficiency of use of the electronics. For example, by separating the components into "hot" and "cold" sections, the entire hot box is heated. This allows for more efficient use of heat resulting in a more energy efficient system. This also allows for the use of standard, off-the-shelf electronic components resulting in lower costs.

[0263] In one embodiment, the control fluid used to control the pumps, valves, etc. is air, which is introduced into the system by operation of one or more air compressors. In one embodiment, the air compressor is kept separate from the blood flow path and dialysate flow path systems within the system, and air from the air compressor is introduced to the various pumps via multiple lines, etc. For example, in one embodiment, an air interface is used that introduces air from the air compressor into the lines, etc. that communicate with the various pumps and chambers.

[0264] FIG. 16 shows a schematic of a dual housing structure in one embodiment. This configuration is useful for cassettes containing multiple pneumatically operated pumps and valves. If the number of pumps and valves in a cassette is increased sufficiently, the cassette containing the pumps and valves will become large, and the pressures on the pumps and valves will increase, making it difficult to properly seal and position all the pumps and valves. This difficulty can be reduced by using two or more different housings. The valves and pumps are mounted in a main housing 41 (pod pump 42) from which connecting tubes 45 extend from an air port 44. The main housing 41 also includes inlet and outlet tubes 43 through which fluid flows in and out of the main housing. The pumps and valves are in communication with the main housing 41 and a small secondary tube-holding housing 46 through the connecting tubes 45. The tube-holding housing 46 is provided with an air interface for each tube. It is easier to properly position and seal each air interface to the base unit of the vessel on the small tube-holding housing 46 than directly on the larger main housing 42 .

[0265] In one set of embodiments, the control fluid (e.g., air) is supplied to the system with one or more supply tanks or other pressure sources. For example, if two tanks are used, one supply tank is a positive pressure tank with a set point of 750 mmHg (approximately 100 kPa, 1 mmHg is approximately 133.3 Pascals), and the other supply tank is a negative pressure, or vacuum tank with a set point of 450 mmHg (approximately 60 kPa). This pressure differential is used to allow precise control of the variable valve to the pod pump between the supply tank and the required pod pressure. A supply pressure limit can be set based on a pressure differential sufficient to control the variable valve and the maximum pressure that can be set for the patient's blood flow pump. Thus, two tanks are used to supply pressure and control fluid for the entire system.

[0266] In one embodiment, two independent compressors supply fluid to a supply tank. For example, the pressure of the tanks is controlled using any suitable technique, whether a simple bang-bang controller (a controller with an open and a closed state) or a sophisticated control mechanism. In one example of a bang-bang controller for a positive pressure tank, the compressor servicing the positive pressure tank is started if the actual pressure is the desired pressure minus hysteresis. If the actual pressure is the desired pressure plus hysteresis, the compressor servicing the positive pressure tank is stopped. The same logic applies for a vacuum tank and vacuum compressor, but with the hysteresis reversed. If the pressure tank is not regulated, the compressor is stopped and the valve is closed.

[0267] Reducing the size of the hysteresis band allows for more precise control of the pressure tanks. However, this requires increasing the compressor operating cycle. If very precise control of these tanks is required, the bang-bang controller can be replaced by a PID controller and the compressor can use a PWM signal. Other control methods are also possible.

[0268] However, in other embodiments, other pressure sources are used, i.e., multiple positive pressure sources and multiple negative pressure sources are used. For example, multiple positive pressure sources are used providing different positive pressures (e.g., 1000 mmHg and 700 mmHg) (approximately 133.3 kPa and approximately 93.3 kPa) to minimize leakage. The negative pressure is -400 mmHg (approximately -53.3 kPa). In one embodiment, the negative pressure source is a vacuum pump and the positive pressure source is an air compressor.

[0269] Certain aspects of the invention include various sensors. For example, various embodiments of the invention disclose systems and methods for fluid processing using a sensor instrumentation system comprising a sensor manifold. Such embodiments include systems and methods for diagnosing, treating, or improving various medical conditions. These inventions, by way of example, include systems and method embodiments for the delivery, measurement, control, and / or analysis of various types of biochemical fluids and therapeutic agents, such as dialysis fluids, and forms of extracorporeal treatment and therapy. Further examples include water treatment systems, water distillation systems, and fluid utilization systems, including diagnosis, treatment, and improvement using fluids such as dialysis fluids.

[0270] Examples of embodiments of the inventions described herein include the dialysis systems and methods described in U.S. Patent Application Serial No. 11 / 871,680, filed October 12, 2007, entitled "Pump Cassette," or in U.S. Patent Application Publication No. 2008 / 0216898, entitled "Instrument Integrated With Cassette System."

[0271] In such systems and methods, one or more sensor manifolds are used so that the media moves from one environment to another, more conductive environment for sensor readings. For example, the cassette manifold is kept in an area that is not susceptible to conditions such as temperature and humidity that are undesirable for sensor instruments such as sensor probes in response to various environmental conditions. Also, the sensor instruments and sensor systems are sensitive and more prone to malfunction than other components of the system. Isolating the sensor instruments and sensor instrument systems from other components of the system using a sensor manifold reduces the impact of the sensor instruments and systems on the other components when inspecting, measuring, repairing, or replacing the sensor manifold. Inspecting, measuring, repairing, or replacing the sensor manifold with minimal impact on other members of the system may be advantageously used in conjunction with U.S. Patent Application Publication No. 2008 / 0216898, entitled "Instrument Integrated With Cassette System." The sensor manifold is replaced somewhat more frequently than other components of the system.

[0272] 53-58 show various embodiments of the sensor manifold. In these embodiments, one or more fluid-using media are contained within the set manifold 4100. For example, media enters the cassette manifold 4100 through connector 4101 and exits the cassette manifold through connector 4102. A flow path is formed between connectors 4101 and 4102 (shown as flow path 4225 in FIG. 54) that runs through the cassette. Similarly, flow paths extend between connectors 4103 and 4104; 4105 and 4106; 4107, 4108 and 4109; 4110 and 4111; and 4112 and 4113 (shown as flow paths 4223, 4220, 4222, 4224, and 4221, respectively, in FIG. 54). In certain embodiments, each flow path includes media having different characteristics. In other embodiments, one or more of the flow paths include the same or similar media. In certain embodiments, the same medium is flowed through multiple flow paths simultaneously to check and / or calibrate an instrument system of sensors associated with such flow paths.

[0273] Referring to FIG. 55, a sensor manifold 4100 for use with the sensor instruments and sensor instrument systems is shown. The cassette includes a top plate 4302 and a base 4301. A flow passage 4225 extending between the connectors 4101 and 4102 extends between the base and the top plate. The cassette is constructed from a variety of materials. Typically, the materials used are rigid and inflexible. In a preferred embodiment, the cassette is formed from polysulfone, but in other embodiments, the cassette is formed from other rigid or thermoplastic materials. Some embodiments of the sensor manifold 4100 may be manufactured using the systems and methods disclosed in U.S. Patent Application Publication No. 2008 / 0216898, entitled "Instrument Integrated With Cassette System."

[0274] Referring again to FIG. 55, the sensor manifold 4100 used with the sensor instrument and sensor instrument system includes a printed circuit board 4304 (PCB) and a PCB cover 4305. Various embodiments include a connector 4303 (also shown in FIGS. 53 and 56B) that mechanically couples the cassette manifold 4100 to a system such as a hemodialysis system. The cassette manifold 4100 employs various methods to hold the layers of the sensor manifold 4100 together. Various embodiments employ 4306 (also shown in FIG. 56B), screws, other embodiments utilize screws, welds, clips, clamps, and other chemical and mechanical joining methods, as shown in FIG. 43.

[0275] FIG. 56A shows an exemplary embodiment of a sensor manifold 4100. A connector 4401 is utilized to introduce or remove media from a flow path 4402. A sensor probe 4404 extending into the flow path 4402 is incorporated into the sensor manifold 4100 to determine a property of the media flowing through a particular flow path of the sensor manifold. In one embodiment, a sensor probe is utilized to sense the temperature or other property of the media. In another embodiment, a sensor probe is utilized to detect the temperature, conductivity, or other property of the media. In further embodiments, three or more sensor probes are utilized. In some embodiments, one or more combination probes for sensing temperature and conductivity are utilized. In other embodiments, the conductivity sensor and temperature detector may be a conventional conductivity sensor or temperature detector. In one embodiment, the conductivity sensor element (or sensor lead) is a graphite post. In other embodiments, the conductivity sensor element is formed from stainless steel, titanium, or any other material that is typically used for measuring post conductivity. In certain embodiments, the conductivity sensor includes a sensor mechanism and electrical connections that transmit a signal from the sensor to a controller or other device. In various embodiments, the temperature detector may be a temperature detector that is typically used (or can be used) for temperature detection.

[0276] Referring to FIG. 56A, the sensor probe 4404 is electrically connected to the PCB 4405. In a particular embodiment, an electrically conductive epoxy is utilized between the sensor element 4404 and the PCB 4405, although any suitable electrical connection method between the sensor element 4404 and the PCB 4405 known in the art may be used to ensure proper electrical connection. The PCB 4405 is illustrated with an edge connector 4406. In various embodiments, the edge connector 4406 is used to transmit the sensor information from the cassette manifold 4100 to the main system. The edge connector 4406 is coupled to a media edge connector (such as the media edge connector 4601 shown in FIG. 58). In various embodiments, the media edge connector 4601 is attached to the hemodialysis machine (not shown). In such an embodiment, guide tracks 4310 and 4311 (as shown in FIG. 55) are utilized to coordinate the relationship between the edge connector 4406 and the media edge connector 4601. Various embodiments also include a connector 4303 (as shown in FIGS. 53, 55 and 56B) for mechanically coupling the cassette manifold 4100 to a system such as a hemodialysis system.

[0277] FIG 56A shows an air trap 4410. In certain embodiments, the air trap 4410 is utilized to capture and clear air from the system. In particular, as shown in FIG 54, media flows through a flow path 4222 between connectors 4107 and 4109 of the sensor manifold 4100. As the flow of media slows around a turn in the flow path 4222 (near connector 4108), air is removed from the following media at connector 4108.

[0278] 56B, there is shown a PCB cover 4305. The PCB cover 4305 is coupled to the sensor manifold 4100 by a connector 4306. An edge connector 4406 is also shown.

[0279] According to certain embodiments, the sensor manifold 4100 is passive with respect to control of flow rate. In such embodiments, the sensor manifold 4100 does not include valves or pumping mechanisms to control the flow of media. In such embodiments, the flow of media is controlled by the exterior of the fluid control device to the sensor manifold 4100. In other embodiments, the sensor manifold includes one or more of known mechanical valves, pneumatic valves, or other types. In such embodiments, the sensor manifold includes one or more pumping mechanisms, including pneumatic pumping mechanisms, mechanical pumping mechanisms, or other types of known pumping mechanisms. Examples of such valves and pumping mechanisms include the valves and pumping mechanisms described in U.S. Patent Application Serial No. 11 / 871,680, filed October 12, 2007, entitled PUMP CASSETTE, or U.S. Patent Application Publication No. 2008 / 0216898, entitled APPARATUS INTEGRATED WITH CASSETTE SYSTEM. 57 shows the base 4301 of the connector 4401. A top plate 4302 is shown along with the connector 4303. A sensor probe 4501 extends through the top plate 4302 into the flow channel 4503. The sensor probe 4501 may be any of a variety of forms including the sensor probes described herein.

[0280] The sensing probes, such as the sensing probe 4501, may all be the same, may be individually selected from various sensors based on the type of function to be performed, or the same probes may be individually modified based on the type of function to be performed. Similarly, the configuration of the flow path, such as the length of the flow path and the shape of the flow path, may be selected based on the function to be performed. As an example, a temperature sensor, such as a thermistor, may be used to detect the temperature of the target medium in the flow path. Also, as an example, one sensing probe configured to measure temperature and conductivity and one sensing probe configured to measure only conductivity may be used to measure the conductivity of the target medium. In other embodiments, two or more sensing probes configured to measure both temperature and conductivity may be used. In various embodiments of such configurations, as an example, there may be a second temperature sensor that is not used during normal operation, or a second temperature may be used for overlapping temperature measurements, or a second temperature may be used for overlapping temperature measurements.

[0281] Referring again to FIG. 57, PCB 4502 is shown with electrical connections 4503. As further shown in FIG. 58, PCB 4602 is shown with electrical connections 4603 for connection to a sensing probe (shown as 4501 in FIG. 45). PCB 4602 also includes openings 4604 for attachment to a top plate (shown as 4305 in FIG. 57). In certain embodiments, electrical connections 4603 may be attached to or fabricated with PCB 4602 with gap 4606. In such embodiments, gap 4606 may be utilized to provide protection to the electrical connections between sensing probe 4501 and PCB 4602 by allowing for contraction and expansion of various components of sensor manifold 4100 with less impact to PCB 4602.

[0282] 58, PCB 4602 is also shown with an edge connector 4605. As described herein, edge connector 4605 can interface with edge connector receiver 4601, which can be coupled to a system, such as a hemodialysis system, that interfaces with sensor manifold 4100.

[0283] Various embodiments of the exemplary sensor manifold 4100 shown in Figures 53-58 may be used in combination with the hemodialysis systems and methods described in U.S. patent application Ser. No. 11 / 871,680, filed Oct. 12, 2007, entitled Pumping Cassette, or U.S. patent application Ser. No. 2008 / 0216898, entitled Cassette System Integrated Apparatus. In one particular embodiment, the sensor manifold 4100 includes all of the temperature and conductivity sensors shown in Figure 59. Figure 59 shows a fluidic design according to one embodiment of the invention described in the above-referenced patent application.

[0284] As an example, in various embodiments, the temperature and conductivity of the target media at location 4701 as shown in FIG. 59 may be measured using the sensor manifold 4100. In such an embodiment, the target media flows via flow path 4220 (as shown in FIG. 54) to tubing connector 4105 (as shown in FIG. 53) and exits at tubing connector 4106 (as shown in FIG. 53). The conductivity of the target media is measured by two sensing probes (not shown) that extend into the flow path 4220, at least one of which is configured to include a temperature sensing element such as a thermistor. The conductivity measurement and the temperature measurement of the target media may be utilized to determine and / or correlate various information of utility to the hemodialysis system. For example, in various embodiments at location 4701 of FIG. 59, the target media consists of water to which a bicarbonate-based solution has been added. The conductivity of the target media at location 4701 may be utilized to determine whether an appropriate amount of bicarbonate-based solution has been added prior to location 4701. In certain embodiments, if the conductivity measurement falls outside a predetermined range or deviates from the predetermined measurement by more than a predetermined amount, the subject medium may not contain an appropriate concentration of bicarbonate-based solution, and in such instances, in certain embodiments, the hemodialysis system is alerted.

[0285] Also, by way of example, in various embodiments, the conductivity of the target media at location 4702, as shown in FIG. 59, may be measured utilizing the sensor manifold 4100. In such an embodiment, the target media flows via flow path 4221 (as shown in FIG. 54) to tubing connector 4112 (as shown in FIG. 41) and exits at tubing connector 4113 (as shown in FIG. 53). The conductivity of the target media is measured by two sensing probes (not shown) extending into flow path 4221, at least one of which is configured to include a temperature sensing element, such as a thermistor. The conductivity measurement and the temperature measurement of the target media are utilized to determine and / or correlate various information of utility to the hemodialysis system. For example, in various embodiments at location 4702 of FIG. 59, the target media consists of water to which a bicarbonate-based solution is added, followed by an acid-based solution. The conductivity of the target media at location 4702 is utilized to determine whether the proper amount of acid-based solution (and bicarbonate-based solution in the previous step) was added prior to location 4702. In certain embodiments, if the conductivity measurement falls outside a predetermined range or deviates from the predetermined measurement by more than a predetermined amount, the target media may not contain the proper concentrations of acid-based solution and bicarbonate-based solution. In such an instance, in certain embodiments, the hemodialysis system is alerted.

[0286] As a further example, in various embodiments, the temperature and conductivity of the target media at location 4703, as shown in FIG. 59, may be measured utilizing the sensor manifold 4100. In such embodiments, the target media flows into and out of the tubing connector 4107 (as shown in FIG. 53) via the flow path 4222 (as shown in FIG. 54) and into and out of the tubing connector 4109 (as shown in FIG. 53). As described herein, air may be removed from the target media by going around a bend in the flow path 4222. In such an example, a portion of the target media is removed to the drain via the tubing connector 4108, with the air being expelled from the void along with the portion of the target media. The conductivity of the target media is measured by two sensing probes (not shown) extending into the flow path 4222, at least one of which is configured to include a temperature sensing element, such as a thermistor. The conductivity and temperature measurements of the target media may be utilized to determine and / or correlate various information of utility to the hemodialysis system. For example, in various embodiments, the measurement of conductivity at location 4703 in Fig. 59 can be utilized to correlate with the clearance rate of the dialysis machine. In such instances, in certain embodiments, this information is then sent to the hemodialysis system.

[0287] Also, as a further example, in various embodiments, the temperature of the target media at location 4704, as shown in FIG. 59, may be measured using a sensor manifold 4100. In such embodiments, the target media flows via flow path 4223 (as shown in FIG. 54) to tubing connector 4103 (as shown in FIG. 53) and exits at tubing connector 4104 (as shown in FIG. 53). The temperature of the target media is measured by one or more sensing probes (not shown) that extend into the flow path 4223. The measurement of the temperature of the target media at location 4704 may be used to determine and / or correlate various information of utility to the hemodialysis system. For example, in various embodiments at location 4704 in FIG. 59, the temperature of the target media is determined downstream of a heating device 4706. If the temperature deviates from a predetermined range or from a predetermined measurement by more than a predetermined amount, the hemodialysis system is alerted. For example, in one embodiment, the target media may be recirculated through the heating device 4706 until the temperature of the target media is within a predetermined range.

[0288] Also, in a further example, in various embodiments, the temperature and conductivity of the target media at location 4705 may be measured using a sensor manifold 4100, as shown in FIG. 59. In such an embodiment, the target media flows through a flow path 4224 (as shown in FIG. 54) into a tubing connector 4110 (as shown in FIG. 53) and exits at a tubing connector 4111 (as shown in FIG. 53). The conductivity of the target media is measured by two sensing probes (not shown) that extend into the flow path 4224, at least one of which is configured to include a temperature sensing element such as a thermistor. The measurement of the conductivity or the measurement of the temperature of the target media may be used to determine and / or correlate various information of utility to the hemodialysis system. For example, the measurement of the temperature and conductivity at location 4705 may be used as an additional safety check to determine whether the temperature, conductivity, and their correlation, composition of the target media are within acceptable ranges before the target media reaches the dialysis device 4707 and thus the patient. In certain embodiments, if the temperature and / or conductivity measurements fall outside a predetermined range or deviate from a predetermined measurement by more than a predetermined amount, the hemodialysis system is alerted.

[0289] For the various embodiments described herein, the cassette may be made of any material, including plastic and metal. The plastic may be flexible plastic, rigid plastic, semi-flexible plastic, semi-rigid plastic, or any combination thereof. In some of these embodiments, the cassette includes one or more thermal wells. In some embodiments, one or more sensing probes and / or one or more other devices for transferring information about one or more characteristics of such a medium of interest are in direct contact with the medium of interest. In some embodiments, the cassette is designed to hold a fluid with a flow rate or pressure. In other embodiments, one or more compartments of the cassette are designed to hold a medium that is largely stagnant or trapped in a conduit even when the medium is flowing.

[0290] In some embodiments, the sensor device may be used based on the need to separate the target medium from the sensing probe, however, in other embodiments, the sensing probe may be used for temperature, conductivity, and / or other detection directly with the target medium.

[0291] Another aspect of the invention relates generally to methods and operation of the system as discussed herein, e.g., the hemodialysis system being primed, flow balanced, emptied, purged with air, disinfected, etc.

[0292] One set of embodiments relates to priming the system with fluid. The fluid to be primed is first introduced into a dialysate tank (e.g., dialysate tank 169). The ultrafilter 73 is then first primed by pushing fluid from the dialysate tank 169 to be ultrafiltered 73 and then out to drain through line 731 via the waste line 39, as shown by the bold black line in FIG. 17A. Any air present in the ultrafilter 73 naturally rises up to the prime port and is flushed to drain.

[0293] 17B, ​​the balancing circuit and its pump 159 are primed by pushing fluid through the ultrafilter 73, through the balancing circuit, and out to drain. The pump 159 is primed by forcing fluid upward (through the ultrafilter to drain). Air entering the dialyzer 14 is bubbled up to the top of the dialyzer and out the outlet of the dialyzer to drain.

[0294] The blood flow pump and tubing are then primed by circulating the fluid through the blood flow circuit and the air trap back to the directing circuit via conduit 67. As seen in FIG. 17C, the fluid passes through the ultrafilter and dialyzer, which forces the fluid through the air trap and down to drain. The air trap traps any air circulating in the blood flow circuit and sends it to drain. Priming can be stopped when the air sensor stops detecting air (and some additional fluid is allowed to flow through the system as a safety margin).

[0295] Another set of embodiments relates to adding air to the system, e.g., emptying various fluids of the system. For example, in one operation, the dialysate tank is emptied. The outlet 226 of the dialysate tank 169 is opened and pump 159 is used to pump fluid from the dialysate tank to drain until air is detected by pump 159 (discussed later). This is shown in FIG.

[0296] Air is also pumped into the balance circuit in certain embodiments. This is shown in FIG. 20. The dialysate 16 outlet 226 is opened to allow air into the dialysate tank. Using pump 159, air is pumped through the outside of the ultrafilter 73. This air pressure moves the fluid outside the ultrafilter inward, forcing it through the dialyzer and down to drain. During this operation, the pump 159 and the outside of the ultrafilter will fill with air.

[0297] Additionally, air is introduced into the blood flow circuit through the anticoagulant pump 80, as shown in Figure 21 A. First, the air is introduced into the pod pump 23 (Figure 21A), from which it is directed either into the arterial line 203 and down to drain (Figure 21B) or into the venous line 204 (through the dialyzer 14) and down to drain (Figure 21C).

[0298] In one set of embodiments, an integrity test is performed. Since the ultrafilter and dialyzer are constructed with membrane materials that do not easily allow air to pass through when wet, an integrity test can be performed by priming the filter with water and then applying compressed air to one side of the filter. In one embodiment, an air outlet is included in one of the blood flow pumps, so the pump chamber can be used to pump air for use in the integrity test. This embodiment takes advantage of the larger pump. The air pressure pushes all the water through the filter, stopping the air flow as soon as the water is replaced. However, if the air flow continues, the membrane will burst and need to be replaced. Therefore, the system is primed with water. First, the mixing circuit is primed first to remove any air prior to the dialysate tank. Then the outside of the ultrafilter is primed next, since it is believed that the ultrafilter will not pass water to the balancing circuit until the outside is primed. The balancing circuit and dialyzer are then primed. Finally, water is primed past the dialyzer to prime the blood flow circuit.

[0299] The mixing circuit is primed by first pushing water using pump 183 to flow through line 281 and bicarbonate source 28, through each of the pumps and line 186 to the dialysate tank 169. The dialysate tank 169 is vented by such air being pushed through air bubbles upwards and expelled through outlet 226. Once air is primed from the dialysate tank 169, the tank fills with water and the priming flow continues from the dialysate tank through the ultrafilter 73 to the drain. This is seen in FIG. 22A. Next, water is primed as previously described (see FIG. 17). Next, the blood flow pod pump 23 is filled with water from the dialysate tank 169, as shown in FIG. 22B, while the balance pump 15 is emptied, as shown in FIG. 22C.

[0300] Testing is performed by using a blood flow pump to push each chamber of water past the dialyzer 14 to the balance pump chamber 15. The balance pump chamber starts empty (FIG. 22C) and is vented to atmosphere so that it is at atmospheric pressure on the dialysate side of the dialyzer 14. See FIG. 22D. Each of the blood flow circuit chambers delivers using a specific pressure and the end of the stroke is determined to determine the flow rate.

[0301] Another integrity test is the ultrafilter flow test, in which the dialysate tank is filled with water, the ultrafilter is primed by pumping water from the dialysate tank through the ultrafilter into line 731, and water is pumped through the ultrafilter, controlling the flow rate and monitoring the delivery pressure needed to maintain flow.

[0302] Another set of embodiments is directed to disinfecting and cleaning the system. This process removes any material that accumulates during treatment and kills any active pathogens. In some instances, germicides are used, but typically heat is used. A dialysate tank is used to hold the water, which is replenished as needed as it is drained.

[0303] The recirculation flow path is shown in FIG. 23. The flow along this path is essentially continuous, with conduit 67 used to connect the blood flow circuit and the directing circuit. The main flow path is heated using heater 72, which is used to raise the temperature of the water in the recirculation flow path, for example to a temperature that can kill any active pathogens that may be present. Some of the water flows to drain, but most is recirculated. Note that in this example, lines 48 and 731 are kept open to ensure that they are properly disinfected. In addition, a flow path through ultrafilter 73 is periodically selected to remove air from the ultrafilter and / or provide a recirculation flow through the same. Temperature sensors (e.g., sensors 251 and 252) can be used to ensure that the proper temperature is met. Non-limiting examples of such sensors are described in co-filed U.S. patent application Ser. No. 12 / 038,474, entitled "Sensor Apparatus Systems, Devices and Methods," which is incorporated herein by reference.

[0304] In one set of embodiments, the system is primed with dialysate as follows: In this operation, the pod pump 280 is filled with water (FIG. 24A), and then the water is pushed back by the pump 183, forcing air out of the top of the bicarbonate source 28. The air is collected in the pod pump 282. See FIG. 24B. The air in the pod pump 282 is then pumped out through the pod pump 280 and line 186 to the dialysate tank 169. The outlet 226 of the dialysate tank 169 is left open to allow air to be pumped out of the system (FIG. 24C). Additionally, acid is pumped from the acid source 29. It is then mixed with the bicarbonate concentrate and water from the bicarbonate source 28. The pump 183 is used to provide sufficient water pressure to fill the bicarbonate source 28 with water, as shown in FIG. 24D.

[0305] The acid and bicarbonate solutions (and sodium chloride solution, if a separate source of sodium chloride is present) are then weighed with the incoming water to prepare the dialysate. Sensors 178 and 179 are used to ensure that the partial mixture of each component with the water is accurate. Good dialysate is pumped into the dialysate tank 14 while dialysate that does not meet specifications is flushed to drain.

[0306] In another set of embodiments, the anticoagulant pump is primed. Priming the pump removes air from the heparin pump and fluid path and ensures that the pressure in the anticoagulant vial is acceptable. The anticoagulant pump can be designed so that air in the pump chamber flows into the vial. Testing is performed by closing all of the anticoagulant pump's fluid valves, measuring the outside volume, applying a vacuum to the FMS chamber, opening the valves to draw fluid from the vial into the pump chamber, measuring the outside volume (again), applying pressure to the FMS chamber, opening the valves to draw fluid back into the vial, and measuring the outside volume (again). The change in outside volume caused by the fluid flow should correspond to the known volume of the pump chamber. If the pump chamber cannot be filled from the vial, the vial pressure is too low and air needs to be drawn in. Conversely, if the pump chamber cannot be drawn into the vial, the vial pressure is too high and some of the anticoagulant needs to be pumped out of the vial. The anticoagulant pumped from the vial during this test may be discarded, for example, via a drain.

[0307] In yet another set of embodiments, while not connected to a patient, the system is flushed with dialysate. This can be done before or after treatment. Before treatment, the dialysate is diverted and some of it is sent to drain to avoid accumulation of sterilant in the dialysate. After treatment, this operation flushes the blood flow path with dialysate, pushing any remaining blood to drain. The flow paths used in this operation are similar to those used with water as already described.

[0308] The acid concentrate may be pumped out of the mixing chamber. Pump 184 is driven, causing pod pump 280 to pump acid from pump 184 and acid source 29, which are mixed in line 186 and sent to drain. Similarly, bicarbonate may be pumped out of the mixing chamber, as shown in FIG. 25. Water is introduced from bicarbonate source 28 using pump 183, and then pod pump 280 is used to pass the water through line 186 to drain.

[0309] In yet another set of embodiments, dialysate prime is removed from the blood flow circuit to avoid giving priming fluid to the patient. Figures 26A and 26B show fluid flowing out of each of the balancing pump chambers and draining to drain. Next, the dialysate side of the dialyzer 14 is closed while blood is introduced into the blood flow path from the patient (Figure 26C). Next, the patient connection is closed while the blood flow pump chamber 23 pushes the priming fluid past the dialyzer and into the balancing circuit (Figures 26D and 26E). This fluid is then pushed to drain as previously described. This operation is repeated as necessary until the priming fluid is sufficiently removed. The balancing pump is then refilled with fresh dialysate and the patient connection is kept closed as shown in Figure 26F.

[0310] In yet another set of embodiments, a bolus of anticoagulant may be delivered to the patient. First, as shown in FIG. 27A, a bolus of anticoagulant is pumped from a vial (or other anticoagulant source) into one chamber of pump 13. The anticoagulant pump alternates between pumping air into the vial and pumping anticoagulant out of the vial, thereby maintaining a relatively constant pressure. The remaining volume is then filled with dialysate (FIG. 27B). The combined fluid is then delivered down arterial line 203 to the patient, as shown in FIG. 27B. In some instances, the same pump chamber is again filled with dialysate (see FIG. 27B) and that volume is delivered to the patient, ensuring that all of the anticoagulant has been properly delivered.

[0311] In yet another embodiment, the system may perform push-pull hemodiafiltration. In such a case, the blood flow pump 13 and balance pump 15 may be synchronized to move fluid back and forth across the dialyzer. In hemodiafiltration, hydrostatic pressure is used to drive water and solutes through the dialyzer membrane from the blood flow circuit to the balance circuit where they are discharged. Without being bound by theory, it is believed that larger solutes are more easily transported by convective forces in hemodiafiltration to the dialysate used.

[0312] In one set of embodiments, the infusion of solution is used to deliver fluid to the patient. As shown in Figure 28, a pump 159 in the directing circuit is used to push fluid from the dialyzer 14 into the blood flow circuit, thereby delivering fluid (e.g., dialysate) to the patient.

[0313] According to another set of embodiments, after repeated use, the dialysis machine may lose its efficiency and ability to function altogether due to compounds that build up and accumulate on the membrane walls of the dialysis machine. Any reference measurement may be used to determine the cleaning rate of the dialysis machine. However, a method to measure how much the dialysis machine is loaded with, i.e., how much the cleaning rate of the dialysis machine has decreased, is to push gas into the blood side of the dialysis machine while liquid remains on the dialysate side of the dialysis machine. By measuring the volume of gas in the dialysis machine, the cleaning rate of the dialysis machine is measured based on the measured volume of gas in the dialysis machine.

[0314] Alternatively, in another embodiment, the cleaning rate may be determined by the air pressure of the system of the present invention as follows: By creating a pressure differential along the dialysis machine and measuring the fluid velocity of the dialysis machine, the cleaning rate of the dialysis machine is correlated / measured or calculated based on the pressure differential and the fluid velocity, based on known correlations or pre-programmed criteria, including, for example, correlation tables, i.e., mathematical relationships. For example, a look-up table may be used, or a determined mathematical relationship may be used.

[0315] The clearance rate of the dialyzer can also be measured using a conductivity probe in the blood tubing plug-back recirculation path. After treatment, the patient is connected to a blood tubing that returns to a disinfection port. Fluid in the blood tubing and dialyzer is recirculated through the connections of these disinfection ports, and the conductivity of the solution can be measured as it passes through a conductivity measuring cell in the recirculation path.

[0316] To measure the cleaning rate of the dialyzer, pure water may be circulated through the dialysate passages and the conductivity of the fluid flowing through the blood recirculation passages is continuously monitored. The pure water removes ions from the solution in the blood flow circuit recirculation passages at a rate proportional to the cleaning rate of the dialyzer. The cleaning rate of the dialyzer can be determined by measuring the rate at which the conductivity of the solution in the blood flow circuit recirculation passages changes.

[0317] The cleaning rate of the dialyzer can be measured by circulating pure water on the one hand and dialysate on the other hand and measuring the amount of fluid passing through the dialyzer using electrical conductivity. In one set of embodiments, in the event of a power outage, it is desirable to return as much blood as possible to the patient. Because one embodiment of the hemodialysis system uses compressed gas to drive the various pumps and valves used, other embodiments may utilize such compressed gas to return blood to the patient in the system in the event of a power outage. Following this method and referring to FIG. 29A, dialysate is pumped across the dialyzer 14 to purify the blood in the blood flow circuit 19 and return it to the patient. Compressed air is used to pump dialysate into the dialyzer 14. Valve 77 releases the compressed air to initiate this function. This method may be used when a power outage or other disturbance prevents the dialysis machine from purifying and returning the patient's blood in the manner that it normally does at the end of a treatment.

[0318] Compressed air is used to increase pressure on the dialysate side of the dialyzer 14, forcing dialysate from within the dialyzer to the blood side, which forces the patient's blood back into the patient's body, allowing the patient or an assistant to monitor the treatment and secure the tubing between the blood flow circuit and the patient once adequately purified blood is returned.

[0319] In one embodiment, a tank 70 is installed in the hemodialysis system and filled with compressed air before treatment begins. The tank 70 is connected to the dialysate circuit 20 via a manually actuated valve 77. When treatment is completed or paused, the valve 77 is opened by the patient or an assistant to begin the cleanse-return treatment. The membrane of the dialyzer 14 allows the passage of dialysate but not air. The compressed air displaces the dialysate until the patient side tubing is secured or the dialysate side of the dialyzer is filled with air.

[0320] In another embodiment, a tank containing compressed air is provided as an accessory to the dialysis machine. In the event that the treatment is stopped early due to a power failure or system fault in the dialysis machine, this tank is attached to the dialysate circuit of the machine to initiate the clean-up-return treatment. As in the previous embodiment, the clean-up-return treatment ends when the patient side tubing is secured or the dialysate side of the dialysis machine fills with air.

[0321] In another embodiment, shown in Figure 29B, an air tank 70 is integrated into the system and attached to a fluid tank 75 with a flexible diaphragm 76 that separates the air from the dialysate. In this case, rather than forcing compressed air into the dialysate circuit 20, the compressed air pushes against the diaphragm 76, increasing the pressure in the dialysate circuit 20. The amount of dialysate that can be moved is determined by the volume of the fluid chamber 75. The cleanse-return procedure is complete when the patient tubing is secured or when all the fluid has been drained and the diaphragm 76 bottoms out against the wall of the fluid chamber 75.

[0322] In any of these embodiments, the operation of the system or method is periodically tested by running the dialysate machine program between treatments. During testing, the user interface prompts the user to perform a cleanse-return treatment and the machine monitors the pressure in the dialysate circuit to ensure proper operation.

[0323] In the system shown in Figures 29A and 29B, blood is drawn from the patient by a blood flow pump 13, pumped through a dialysis machine 14, and returned to the patient. These components and the tubing connecting them constitute a blood flow circuit 10. The blood contained in the blood flow circuit 10 must be returned to the patient when treatment is completed or interrupted.

[0324] Dialysate is drawn from the dialysate tank 169 by the dialysate pump 159 and passed through the heater 72 where it is heated to body temperature. The dialysate then flows through the ultrafilter 73 which removes pathogens and pyrogens that may be present in the dialysate. The dialysate then flows through the dialyzer to provide therapy and is returned to the dialysate tank.

[0325] The bypass valve 74 can also be used to isolate the dialyzer 14 from the rest of the dialyzer circuit 20. To isolate the dialyzer 14, two valves connecting the dialysate circuit 20 to the dialyzer are closed and one valve is opened which shunts dialysate around the dialyzer.

[0326] This cleanse-return procedure can be used whether the dialyzer 14 is isolated or not, and is used when the procedure is completed or interrupted. When the dialysate machine is turned off and stopped, the pump does not run. When the patient is ready for the cleanse-return procedure, the air valve 77 is opened by the patient or assistant. Air from the compressed air tank 70 flows into the dialysate circuit 20, increasing the pressure on the dialysate side of the dialyzer 14. This increase in pressure can be achieved by allowing air to enter the dialysate circuit directly, as shown in Figure 29A, or indirectly by pushing against a septum 76, as shown in Figure 29B.

[0327] Air pressure on the dialysate side of the dialyzer causes a portion of the dialysate to flow from the dialyzer 14 into the blood flow circuit. This dialysate displaces the blood, purifying it and returning it to the patient. The patient or assistant can observe the purification process by keeping an eye on the dialyzer 14 and the blood tubing. The dialysate starts in the dialyzer, displaces the blood, making it cleaner. This cleaner solution moves from the dialyzer towards the patient. Once it reaches the patient, the blood tubing fixture 71 is used to clamp the blood tubing, terminating the purification-return process. If the purification-return process of one line is faster than the other line, the faster line may be fixed first and the slower line fixed later.

[0328] Once the cleanse-return procedure is complete, the blood lines are clamped and the patient is disconnected from the dialysis machine. An implementation of one embodiment of the system and method is shown in Figure 29A and takes advantage of the hydrophilic nature of the material used to form thin tubes within the dialysis machine 14. When the material is wet, the dialysate can pass through but air cannot. When implementing the embodiment shown in Figure 29A, air can enter the dialysis machine 14 but cannot pass beyond the blood flow circuit 10.

[0329] In either implementation, the amount of dialysate that can pass through the dialyzer 14 is limited. This limit is imposed by the size of the compressed air tank 70, the amount of dialysate contained in the dialyzer 14, and, in the embodiment shown in Figure 7B, the size of the fluid tank 75. It is advantageous to limit the amount of dialysate pumped into the dialyzer, since providing the patient with excess fluid would negate the therapeutic benefit of removing fluid during treatment.

[0330] In another embodiment, during a power outage, the air pressure that moves dialysate from the dialysate circuit to the dialyzer can be derived from a pressurized air tank that normally drives the membrane pumps and also serves as a pressure source for the fluid management system measurements. As shown in FIG. 80, for example, this air pressure source can be accessed via the fluid management system pathway 170 used to monitor the dialysate tank 169. In an embodiment, the manifold valves that direct air pressure or vacuum to the various pumps and valves of the liquid flow paths of the hemodialysis device are electrically operated. In some embodiments, the valves of the liquid flow paths of the hemodialysis device themselves can be electrically operated. They can be selected or pre-set to have default open or closed positions in the absence of electrical power. For example, if the default position of a manifold valve is closed, no air pressure (or vacuum) is transmitted to that object. Similarly, if the default position of a manifold valve is open, then the associated pressure or vacuum source can pressurize a downstream device (such as a membrane-based pump, a membrane-based valve, or another type of valve). If the valves that directly control the flow of the liquid flow paths themselves are electrically operated, the valves can be selected to have default positions that either close or open their respective flow paths. In the example illustrated in FIG. 80, the manifold valve 170a and the fluid management system valve 170b can be configured to have, for example, a default open position, to allow pressure from the pressurized air tank to be transferred to the dialysate tank 169. By configuring various other manifold valves in their appropriate default positions, the corresponding flow path valves that they control can open a path from the dialysate tank 169, through the outer dialysate pump circuit 159, the ultrafilter 73, a portion of the balancing circuit 143, and finally to the dialyzer 14. In this way, in the absence of electrical power and in the absence of impedance on the blood flow side of the dialyzer 14, dialysate from the dialysate tank 169 can be allowed to flow to the dialyzer 14, allowing blood to be rinsed back. During normal dialysis, the control software can ensure that there is enough dialysate in the dialysate tank 169 to rinse back all of the blood present in the blood tubing set.

[0331] In an alternative embodiment, the valves that directly control flow in the dialysate flow paths between the dialysate tank and the dialyzer, if they are themselves electrically actuated, can be selected to have a default open position, whereas other valves that control flow in paths that deviate from the dialyzer, can be selected to have a default closed position.

[0332] For example, in Fig. 80, the default configuration of the appropriate manifold valves would have the inlet and outlet valves 171 of the outer dialysate pump circuit 159 and the balancing circuit valve 172 remain in the "open" position to provide a flow path to the dialyzer 14. Conversely, the inlet feed valve 173a and recirculation valve 173b of the dialysate tank 169 and the drain valve 174 of the ultrafilter 73 could have default positions of "closed" in the absence of electrical power to prevent dialysate from being pumped to drain. Additionally, the inlet valve 175 of the inner dialysate pump circuit 15 and the inlet valve 176 of the bypass or ultrafilter pump circuit 35 could have default positions of "closed" to prevent dialysate from entering that path from the dialyzer 14 in the absence of electrical power.

[0333] To avoid uncontrolled rinseback, the arterial supply line and the venous return line of the blood tubing set can be compressed by an occluder mechanism that maintains a default "occluded" position when there is no power and moves to a "non-occluded" position during normal dialysis. The occluder can be positioned to simultaneously occlude both the arterial line before it reaches the blood pump cassette and the venous line after it leaves the dialyzer or bubble trap. In a preferred embodiment, before rinseback is enabled, the patient, operator, or assistant exits the arterial line from the patient's vascular access site when a rinseback is scheduled or when initiating a power outage related rinseback. A suitable connector (such as a needle or needleless spike or luer lock connector) is placed on the end of the arterial line and further connected to an air trap (such as air trap 19) in the venous return line. This helps to prevent air trapped in the blood flow path at the top of the blood pump cassette or the top of the dialyzer from inadvertently rinsing back toward the patient's vascular access. Once the arterial line is connected to the air trap, the patient, operator, or assistant may manually move the occluder to the "unoccluded" position, which reduces pressure in the venous return line and causes pressurized dialysate from the dialysate circuit to push blood in the blood tubing set towards the patient's vascular access. If the patient observes air in the venous line downstream from the air trap, the patient simply reconnects the occluder to stop the rinseback.

[0334] Although the above rinseback procedure is described using dialysate as the solution that moves blood in the blood flow path and ultimately to the patient's vascular access, any electrolyte solution that is physiologically compatible and safely miscible with blood may be used in the rinseback procedure. Furthermore, rinseback techniques need not be limited to dialysis systems. Any system that circulates a patient's blood extracorporeally could potentially benefit from an emergency rinseback system and method. Thus, a filter (dialyser or ultrafilter) with a semipermeable membrane could be introduced into the blood flow path of the extracorporeal system. The other side of the semipermeable membrane would then be exposed to the electrolyte solution in the flow path that can be pressurized by a compressed gas source communicating through a valve.

[0335] Another aspect of the invention relates to a user interface for the system. The user interface is operated by an individual, such as a patient, family member, assistant, professional health care provider, or maintenance technician, to input selections, such as treatment options, and to receive information, such as information regarding a treatment procedure, treatment status, device status / status, and / or patient condition. The user interface is attached to the treatment device and controlled by one or more processors of the treatment device. In other embodiments, the user interface may be a remote device that receives, transmits, or transmits data and instructions regarding a treatment procedure, treatment status, and / or patient condition, and the like. The remote device may be connected to the treatment device by any suitable technology, including wireless communication utilizing optical and / or electronic radio, Bluetooth, RF frequencies, light frequencies, IR frequencies, ultrasonic frequencies, magnetic effects, and the like, to transmit and / or receive data and instructions from or to the treatment device. In some embodiments, a display may be used to indicate when data and / or instructions have been received by the treatment device or the remote device. The remote device may include an input device, such as a keyboard, touch screen, capacitive input device, and the like, to input data and / or instructions to the treatment device.

[0336] In some embodiments, one or more processors of the processing unit may include a unique identification code, and the remote device may include functionality for reading and learning the unique identification code of the processing unit. Alternatively, the processing unit and the remote device may be user programmed with a unique identification code. The processing unit and the remote device may use the unique identification code to substantially avoid interference with other receivers, including other processing units.

[0337] In one set of embodiments, the treatment device may include one or more processors connected to a web-enabled server, which may drive a user interface device. In one embodiment, the device uses an external CPU (e.g., a GUI graphical user interface) to communicate via Internet Protocol with a WEB-embedded server built into or connected to the treatment device. The WEB pages may be carried within the device, or the graphical user interface may communicate directly via IEEE 802.11b or other similar wired or wireless Ethernet equivalents. The graphical user interface may be operated by an individual, such as the patient, family member, assistant, professional healthcare provider, or maintenance technician, to input options, such as treatment options, and to receive information, such as information regarding treatment procedures, treatment status, device status / status, and / or patient status.

[0338] In another embodiment, an embedded web server built into or connected to the treatment device can communicate with appropriate sites on the Internet. The Internet sites require a password or other user credentials for access. In another embodiment, different types of users and access providers can access different information. For example, a patient or professional healthcare provider can have full access to the patient's treatment options and patient information, while a family member can be granted access to specific patient information such as condition and duration for a given treatment and frequency of treatment. A maintenance technician, dialysis center, or treatment device provider can access other information such as troubleshooting, preventive maintenance, clinical trials, etc. The use of a web-enabled server allows one or more individuals to simultaneously access patient information for various purposes.

[0339] Through the use of remote devices (e.g., through wired or wireless communication, Internet Protocol, or an Internet site utilizing a web-enabled server), dialysis centers can more effectively monitor each patient and / or efficiently monitor multiple patients simultaneously. In some embodiments, the remote devices can function as night monitors and night alarms to monitor patients during overnight dialysis treatments and alert if a patient's condition does not meet certain parameters. In some embodiments, the remote devices can be used to alert patients, family members, assistants, professional medical providers, or maintenance technicians. These alarms can alert individuals of certain conditions, such as, but not limited to, fluid leaks, blockages, temperatures outside normal parameters, etc. These alarms can be audible, visual, and / or vibrating alarms.

[0340] FIG. 60 shows an example of a user interface / treatment device combination. Specifically, FIG. 60 shows a perspective view of an exemplary hemodialysis system 6000 including a dialysis unit 6001 and a user interface unit 6002. In this example, the dialysis unit 6001 includes a housing 6004 that includes components suitable for performing hemodialysis. For example, the dialysis unit 6001 may include a mixing circuit 25, a blood flow circuit 10, a balancing circuit 143, and an external or outer dialysate circuit 142, for example, as described in connection with FIG. 2A. The dialysis unit 6001 may also include all patient access connections and dialysate fluid connections necessary for operation of the system 6000.

[0341] The user interface unit 6002 comprises a user interface 6003 that a user, such as a hemodialysis patient, may use to control the operation of the dialysis unit 6001 via a connection 6006. The connection 6006 may comprise a suitable data connection, such as a bus, a wireless connection, a connection by a local area network (e.g., an Ethernet local area network), and / or a connection by a wide area network (e.g., the Internet). The user interface unit 6002 further comprises a housing 6005 that contains components for enabling operation of the user interface. In the example of FIG. 60, the user interface 6003 comprises a display screen with a touch-sensitive overlay that allows touch control and interaction with a graphical user interface displayed on the screen. However, many other types of user interfaces are possible, such as a screen with separate input mechanisms such as a keyboard and / or a pointing device. The user interface 6003 may also include other features, such as push buttons, a speaker, a microphone for receiving voice commands, etc.

[0342] Although the hemodialysis system 6000 of Figure 60 includes a user interface unit 6002 that is remotely physically coupled to the dialysis unit 6001, many alternative configurations are possible. For example, the user interface unit 6002 may be mounted to or within the dialysis unit 6001. For convenience, a user interface unit 6002 so mounted may be removable from its mounting for use at another location or position.

[0343] FIG. 61 shows an exemplary hardware configuration for each of the dialysis unit 6001 and the user interface unit 6002. These are each controlled by a separate CPU, separating the time and safety critical software from the user experience software. Once a treatment has begun, it can be completed even if the user interface computer fails or is disconnected. This can be supported by having some physical control buttons and indicator lights duplicated to those implemented in the user interface unit 6002 and connected to the control processor of the dialysis unit 6001. The dialysis unit 6001 comprises an automation computer (AC) 6106 that controls the hardware actuators and sensors 6107 that communicate and monitor the hemodialysis related treatment. The automation computer 6106 comprises an automation control unit 6108 that includes an automated computer processing unit 6109 and an automated computer readable medium 6110. The automated computer processing unit 6109 comprises one or more processors capable of executing instructions and operating on data recorded on the automated computer readable medium 6110. The data may relate to, for example, a hemodialysis process that has been or can be performed on a patient. The system's architecture gives the automation computer 6106 software accessible safety sensors 6107 and the ability to command fail-safe conditions (safely pausing or interrupting therapy). A parallel independent semiconductor device based system can perform similar checks as the software controls to provide a redundant safety system. This can be implemented, for example, in a field programmable gate array ("FPGA"), and can also command fail-safe conditions independent of the software system if one or more safety checks are not passed. The integrity of the pneumatic, hydraulic and electrical systems can be checked both during and between therapy sessions. Instructions may comprise, for example, an operating system (e.g., Linux), application programs, program modules, and / or other coded instructions to perform a particular process.

[0344] The automated computer readable medium 6110 may comprise any available medium accessible by the automated computer processing device (dialysis processing device) 6109. For example, the automated computer readable medium 6110 may comprise a computer storage medium and / or a communication medium. The computer storage medium may include any one or more of volatile and / or non-volatile memory and removable and / or non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data. Examples of such computer storage media include, but are not limited to, RAM, ROM, solid state disks, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to store the desired information and that can be accessed by the automated computer processing device 6109. The communication medium typically embodies the computer readable instructions, data structures, program modules or other data in a modulated data signal such as a carrier wave or other transport mechanism and includes any information delivery medium. The term "modulated data signal" means a signal that has one or more of its characteristics set or changed in such a manner as to encode information in the signal. By way of example, communication media includes wired media such as a wired network or direct-wired connection, and / or wireless media such as acoustic, RF, infrared and other wireless media.

[0345] The various components of the automation computer 6106, such as the automation computer readable medium 6110 and the automation computer processing unit 6109, may be electrically coupled via a system bus. The system bus may comprise any of several types of bus structures including a memory bus or memory controller, a peripheral bus, and a local bus utilizing any of a variety of bus architectures. By way of example, such architectures include Industry Standard Architecture (ISA), MicroChannel Architecture (MCA), Enhanced ISA (EISA), Video Electronics Standards Association (VESA), and Peripheral Component Interconnect (PCI).

[0346] The automation computer 6106 may further include a dialysis universal serial bus (USB) interface 6113 to allow various input and / or output devices to be coupled to the automation control unit 6108. Examples of such input and / or output devices include monitors, speakers, printers, keyboards, pointing devices (e.g., mice), scanners, personal digital assistants, microphones, and other peripheral devices. USB is only one example of a type of interface that can be used to connect peripheral devices. Other interfaces may be used instead.

[0347] As described above, the dialysis unit 6001 includes components for performing and monitoring the hemodialysis process. Such components include sensors and actuators 6107. To couple the automation control unit 6108 to the sensors and actuators 6107, the automation computer may include a hardware interface 6111. The hardware interface 6111 may send inputs to and receive outputs from the sensors and actuators 6107.

[0348] The automation computer 6106 may further comprise an automation network interface 6112 that allows the computer to be connected to network-connected devices, such as those in a local area network (LAN) and / or a wide area network (WAN). For example, the automation network interface 6112 may comprise a LAN, such as an Ethernet LAN, and / or a WAN, such as the Internet, and may allow the dialysis unit 6001 to exchange data with the user interface unit 6002 over a network 6114, which may be wired or wireless. Of course, the dialysis unit 6001 may alternatively or additionally exchange data with the user interface unit 6002 by way of a bus or other data connection.

[0349] The user interface unit 6002 comprises a user interface computer 6119 that controls a user interface that displays information to a user and receives input from the user, such as a graphical user interface 6115. Similar to the automation computer 6106, the user interface computer 6119 comprises a UI control unit 6116 having a UIC processing unit 6117 and a UI computer readable medium 6118, a user USB interface 6121, and a UI network interface 6120, each of which are the same or similar to their counterparts in the automation computer 6106. In addition, the user interface computer 6119 may include a graphics interface 6122 that couples the UI control unit 6116 to the graphical user interface 6115. In a preferred implementation, the software of the user interface computer 6119 is not tasked with interpreting data received from the automation computer 6106, but rather with displaying the data in an understandable manner to the user.

[0350] FIG. 62 illustrates, in a schematic manner, various exemplary software processes that may be executed on the automation computer processor 6109 and UIC processor 6117 of the automation computer 6106 and user interface computer 6119, respectively. The illustrated processes may be launched and monitored by executive processes. For example, the automation computer processor 6109 and UIC processor 6117 may each include an automation computer executive 6201 and a UIC executive 6207 to launch processes within a given processor and provide a communication mechanism to determine the execution status of child processes. The executives monitor each child process to ensure that each starts and continues to run as expected. In particular, the automation computer executive 6201 and UIC executive 6207 may detect hung processes. If a child process terminates or fails, each executive process may take appropriate action to keep the system running safely. This may include terminating the process and notifying the UIC executive 6207, halting the system, or restarting non-safety-critical processes. In the UIC processor, this involves notifying an operator and completing the action using a hard key. The automation computer executive 6201 and UIC executive 6207 may use Linux parent-child process relationships to receive notifications from the operating system about child process terminations. This allows handling of abnormal process terminations as well as expected terminations during power off sequences. The automation computer 6106, automation computer executive 6201, and UIC executive 6207 may have a message interface between them to share information about their respective running processes. Periodically sharing state information allows both the automation computer processing unit (processor unit) 6109 and the UIC processing unit 6117 to have a consistent view of the state of all system processes.The Automation Computer Executive 6201 can control a watchdog signal to the electronics and put the machine into a fail-safe state if any child process becomes unresponsive or requires a fail-safe state. Preferably, this control can occur directly through hardware registers without the need for an I / O server.

[0351] As shown in the example of FIG. 62, the automated computer processing device 6109 includes an I / O server process 6205. The I / O server process 6205 provides an interface to directly access hardware such as the dialysis unit's sensors and actuators to allow other processes to request read operations. For example, the I / O server process 6205 may isolate the machine controller from the details of the hardware by providing an interface for the machine controller 6202 to read and write the sensors and actuators. In the described embodiment, only the machine controller 6202 may communicate with the I / O server process 6205. The interface may be synchronized with a message queue.

[0352] The machine controller 6202 described above serves as an interface to control the operation of the machine and report the operating status of the machine. Specifically, the machine controller 6202 implements controllers that read sensors and set actuators via the I / O server process 6205. These controllers are designed to be programmable for functions (e.g., delivery and heating) with various parameters (e.g., flow rate, phase, pressure and temperature) to support various hemodialysis therapies. The configuration of the controllers may be established by state machines that implement higher level machine functions such as priming and disinfection. The state machines configure the flow paths and controller set points based on the machine capabilities and higher level commands received from the therapy application 6203 described below. The machine controller 6202 may also perform safety cross-checks on various sensors to maintain a safe and effective therapy. The machine status and health information may be recorded in a database by the machine controller 6202.

[0353] The therapy application 6203 drives the patient's therapy by commanding the machine controller 6202 to perform individual operations related to the hemodialysis process. In particular, the therapy application 6203 may execute state machines that perform therapy and control the mode of the system. The state machines control, for example, priming the system with dialysate, connecting the patient to the machine, dialyzing the patient, rinsing the patient's blood back into the body, cleaning the machine, disinfecting the machine, running tests on the machine's parts, replacing old or worn parts, and waiting for the patient to return for the next treatment. The therapy application 6203 issues commands to the machine controller 6202 to perform therapy operations and requests status information from the machine controller 6202. To obtain patient, therapy, and machine information, the therapy application 6203 may interface with databases to access information and store treatment status information. The therapy application 6203 may use the interface with the user interface model 6206 process described below to transfer user selections to the user interface and report back the therapy status. The Therapy Applications 6203 implements state machines including treatment preparation, patient connection, dialysis, solution infusion, patient disconnection, recycle preparation, disinfection, cleaning and disposable replacement. The Therapy Applications 6203 process may also include a main control module responsible for sequencing the activities of all other Therapy Applications that prepare and deliver the routine treatment.

[0354] Similar to the therapy application 6203, the user interface (UI) model 6206 runs on the automated computer processor 6109. The UI model 6206 aggregates information describing the current state of the system and the patient and supports changing the state of the system via operator input. The UI model 6206 separates the content of the user interface display from non-content related aspects (e.g., presentation) by allowing the content of the user interface to change without affecting the underlying software that controls the display of the user interface. In this way, changes to the UI model 6206 can be made without affecting the visual experience that the user interface provides. The UI model 6206 does not have a display directly associated with it, but rather commands the graphical user interface (GUI) 6115 (FIG. 61) of the user interface unit 6002 to display screens and return information. For example, when the user navigates to a new screen, the UI model 6206 sends information to the user interface unit 6002 that is used in generating the new screen. The UI model 6206 may also validate user data received from the user interface unit 6002 and, once validated, forwards the user data or commands based thereon to the therapy application 6203.

[0355] To create an interactive display for the graphical user interface 6115 (FIG. 61) of the user interface unit 6002, a UI view process 6208 runs on the UI processor (UI processor) 6117 of the user interface computer. The UI view process 6208 does not need to keep track of the screen flow or treatment state. Instead, it receives information from the UI model 6206 running on the automation computer processor 6109, specifying how and what to display to the user about the current state of the treatment and what can be input. As a result, the graphical user interface 6115 can be terminated and restarted without affecting the operation of the system. In addition, the graphical user interface 6115 does not need to be responsible for validating user input. All inputs and commands received by the UI view 6208 are sent to the UI model 6206 for validation there. In this way, all safety-critical aspects of the user interface can be handled by the UI model 6206. Certain processes, such as those that are not safety-related, do not require the involvement of the UI model 6206. For example, it is not necessary for the UI model 6206 to perform any function to access information stored in a database on the user interface computer.

[0356] Also executing on the UIC processing unit (UI processor) 6117, the remote access application 6210 provides an interface for external devices. For example, the remote access application 6210 may provide an interface for treatment monitoring, remote services, online assistance, and other external services if permitted by the user. The remote access application 6210 may be responsible for initiating remote connections, verifying access, and supporting communications from remote sites to the UI model 6206.

[0357] The database access application 6209 stores and retrieves data from one or more databases, for example located on the user interface computer 6119 (FIG. 61). The database access application 6209 enables the storage and retrieval of records and provides a common access point for information required by the system, such as prescription, schedule and history information. The database access application 6209 may manage the database files so that they are backed up periodically.

[0358] 62, the functionality of the user interface software may be split between the automation computer processor 6109 and the UIC processor 6117. The UI model 6206 and UI controller 6204 may work together to separate control of the UI data and state information of the automation computer 6106 so that software and screen design changes to the UI view 6208 only affect the non-safety critical software of the user interface computer 6119. In this manner, the UI view 6208 can be executed as a non-safety critical process while the UI model 6206 is tested and executed at a safety critical level.

[0359] In general, treatment and machine status information displayed on the user interface computer 6119 originates exclusively from the UI model 6206. According to one embodiment, all data displayed on the user interface computer 6119 originates from the UI model 6206 and is either directly retrieved from the database layer or is temporary edited data entered by the user. The only local state information displayed or stored in the UI view 6208 may be this temporary edited data and details that allow for local rendering of the information. In this way, the UI model 6206 may maintain and control the display of all identified data. If desired, non-safety related data may be handled exclusively by the UI view 6208. For example, changes in the display language or other display changes that do not affect the safety related content may be made using the UI view 6208 without affecting the UI model 6206 in any way.

[0360] It should be appreciated that the association of software processes with the automated computer processor 6109 and UIC processor 6117 illustrated in FIG. 62 is merely one example of a software configuration for performing the functions described above. The processes may be distributed in a variety of alternative ways between the automated computer processor 6109 and UIC processor 6117, and / or other local or remote processors. Also, not all processes are required for a hemodialysis system. Certain processes may be omitted or modified while maintaining the functionality of the hemodialysis system.

[0361] FIG. 63 is an example showing how information regarding the user interface flows between the hardware and software components of the user interface computer 6119 and the automation computer 6106. Information may flow and be handled such that safety-critical information is only processed at or below the UI model layer. The safety-critical information relates to the operation of the hemodialysis system. For example, the safety-critical information may comprise a state of a dialysis process, a state of a screen of a graphical user interface, and / or an algorithm for performing or monitoring a treatment. In some examples, the safety-critical information may be displayed in a graphical user interface. In that case, the safety-critical information may comprise content that is critical to the operation of the hemodialysis system. Non-safety-critical information displayed in the user interface may comprise aspects of the display that relate to visual presentation and are not critical to the operation of the hemodialysis system.

[0362] As illustrated in FIG. 63, the UI model 6206, UI controller 6204 and therapy application 6203 described in relation to FIG. 62 execute on the automation computer 6106. The UI view 6208 executes on the user interface computer 6119 along with the auxiliary applications 6301. The database 6302 or its interface (e.g., database server) may also reside on the user interface computer 6119. The UI model 6206 aggregates information describing the current state of the system and the patient and commands the graphical user interface to display screens and return information. For user control of the system, it validates user data and commands before forwarding them to the therapy application. The UI model 6206 keeps the content of the user interface independent of the display. The graphical user interface preferably does not maintain machine state information, allowing the user interface to be changed or temporarily disconnected without affecting the underlying software. The graphical user interface is not responsible for validating user input, but may restrict various input ranges while leaving validation the responsibility of the UI model 6206.

[0363] Considering first the flow of information between the UI view 6208 and the UI model 6206, the UI view acts as a client of the UI model as described below. The UI view 6208 requests the current screen state from the UI model 6206, and the UI model responds to the request. The response determines the state of the main screen of the UI view 6208. The UI model 6206 may publish data and state information in sufficient detail to allow the UI view 6208 to present different subsets of display information depending on the level of detail requested by the user. For example, the UI view 6208 could present the same treatment state as either an overview or a step guide using the same information from the UI model 6206. Presentation of information may be based on, for example, the mode selected by the user (e.g., "expert" or "novice"). The UI model 6206 may provide the UI view 6208 with the ability to record sub-state information, such as the current presentation mode, in the UI model. This allows the graphical user interface to resume operation in its previous state if the user interface computer 6119 is reset.

[0364] The UI model 6206 accepts user input data and requests, such as a request to start treatment, from the UI view 6208. Data integrity of the information submitted via the UI view 6208 can be enhanced or ensured in several ways, such as sending the data submitted via the UI view 6208 via the UI model 6206 for validation. That is, while the data is edited locally in the UI view 6208, the accepted data may be moved to the UI model 6206 where it may be validated before being stored in the database 6302 and / or sent to the treatment application 6203. Validation may include, for example, verifying that the entered data is within expected ranges. The entered information may also be read back from the database 6302 by the UI model 6206 before being sent to the UI view 6208 for display to the user. This process may be used to ensure that the d...

Claims

1. 1. A method for disinfecting a blood path and a dialysate path of a dialysis system, the dialysis system having at least one door closing a portion of the blood path and the dialysate path, the method comprising: storing sterilization parameters including a sterilization temperature and a sterilization time in at least one storage medium; configuring the blood path and the dialysate path to provide a recirculation flow path including the blood path, the dialysate path, and a heater; circulating a single fluid through the recirculation flow path; monitoring the temperature of the single fluid with at least one temperature sensor in the recirculation flow path; monitoring a status of the at least one door; stopping the flow of the single fluid in the sterilization method if the at least one door is in an open state; receiving a user input indicating that the at least one door is closed; and determining that disinfection of the blood path and the dialysis fluid path is completed when the temperature of the single fluid at the temperature sensor remains at or above the disinfection temperature for at least the disinfection time.

2. the configuring step includes connecting two conduits of the blood pathway to a dialysate directing circuit of the dialysate pathway; The disinfection method according to claim 1.

3. The disinfection method further comprises: determining that at least one of the monitored temperatures of the single fluid is below the disinfection temperature; and in response to determining that at least one of the monitored temperatures is below the disinfection temperature, heating the single fluid to at least the disinfection temperature. The disinfection method according to claim 1.

4. The method further comprises heating the single fluid to a temperature equal to or greater than the disinfection temperature. The disinfection method according to claim 1.

5. monitoring the temperature of the single fluid with a plurality of temperature sensors; and determining that disinfection of the blood path and the dialysis fluid path is complete when the temperature of the single fluid at each of the plurality of temperature sensors remains at or above the disinfection temperature for at least the disinfection time. The disinfection method according to claim 4.

6. The configuring step includes connecting a dialysate drain line to a water inlet line. The disinfection method according to claim 1.

7. periodically selecting the dialysate path through the filter such that air is removed from the filter. The disinfection method according to claim 1.

8. and directing a portion of the single fluid to a drain. The disinfection method according to claim 1.

9. The recirculation flow path includes a dialysis device. The disinfection method according to claim 1.

10. the at least one temperature sensor is located in the dialysate pathway. The disinfection method according to claim 1.

11. the single fluid is water; The disinfection method according to claim 1.

12. and heating the single fluid in response to the temperature of the single fluid being below a threshold value for more than a threshold time period. The disinfection method according to claim 1.

13. 1. A method for disinfecting a blood path and a dialysate path of a dialysis system, the dialysis system having at least one door closing a portion of the blood path and the dialysate path, the method comprising: Electronically receiving sterilization parameters including sterilization temperature and sterilization time; configuring the blood path and the dialysate path to provide a recirculation flow path including the dialysate path and the blood path, the recirculation flow path including a heater; controlling a plurality of actuators to circulate fluid through the recirculation flow path; monitoring the temperature of the fluid with at least one temperature sensor; monitoring a status of the at least one door; stopping the flow of fluid in the sterilization method if the at least one door is in an open state; receiving a user input indicating that the at least one door is closed; and determining whether the temperature of said fluid, as monitored by said at least one temperature sensor, remains at or above said disinfection temperature for at least said disinfection time.

14. monitoring the temperature of the fluid with a plurality of temperature sensors; and determining whether the temperature of the fluid monitored by each of the plurality of temperature sensors remains at or above the disinfection temperature for at least the disinfection time. The disinfection method according to claim 13.

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