Occlusion assembly and actuation method thereof

Abstract

To provide an occlusion assembly for closing a folding type tube of a medical infusion device.SOLUTION: An occlusion assembly includes: first and second occlusion members which are positioned to be opposite from each other to be adjacent respectively to paired first and second foldable tubes such that a space is formed between them, while the space is located on the opposite side of the foldable tubes, and the occlusion members are adjacent to the foldable tubes; an expanding portion which forcibly moves portions of the occlusion members in a manner to be separate from each other to increase the size of the space, and forcibly moves a tube contact portion of each of the occlusion members relative to the foldable tubes adjacent to the occlusion members such that the foldable tubes are closed; and an actuator configured and positioned for moving the expanding portion.SELECTED DRAWING: Figure 54

Description

Technical Field

[0001] The present invention generally relates to hemodialysis and similar dialysis systems, such as systems capable of treating blood or other body fluids outside the body.

Background Art

[0002] Due to many factors, hemodialysis is inefficient, difficult, and costly. These factors include the complexity of hemodialysis, concerns about the safety associated with hemodialysis, and the large amount of dialysis fluid required for hemodialysis. Furthermore, hemodialysis is usually performed at a dialysis center that requires skilled technicians.

Summary of the Invention

Problems to be Solved by the Invention

[0003] Therefore, simplifying and improving the efficiency of the dialysis method can potentially have a significant impact on the treatment cost or the patient's out-of-pocket expenses.

Means for Solving the Problems

[0004] In one aspect of the present invention, a drainage cassette for a dialysis unit includes a venous connection port connected to and in fluid communication with a venous blood line connector, an arterial connection port connected to and in fluid communication with an arterial blood line connector, a fluid channel fluidly connecting the venous connection port and the arterial connection port, a drainage outlet port configured to be removably coupled to a drainage connector of an exposed panel of the dialysis unit and in fluid communication with the fluid channel, and a valve configured to control the flow in the fluid channel. The valve can be configured to controllably open and close the fluid communication of the fluid channel between the drainage outlet port and the venous connection port, or to controllably open and close the fluid communication in the fluid channel between the drainage outlet port and the arterial connection port. Such a configuration enables, for example, purging and / or flushing of the venous and arterial lines for drainage during treatment preparation. Further, the drainage cassette can be made removable from the dialysis unit, allowing an operator to remove and replace the blood-contacting portion of the drainage cassette when preparing the dialysis unit for treating another patient.

[0005] In one embodiment, the drainage cassette can include a body forming the arterial connection port, the venous connection port, and the fluid channel. A check valve can be configured to allow flow out of the fluid channel and out of the drainage outlet port, and to prevent flow from the drainage outlet port into the fluid channel. Thus, fluid or other substances in the drainage line downstream of the check valve can be prevented from entering the fluid channel. The valve controlling the flow in the fluid channel can be a pneumatic control valve, and a pneumatic control port of the drainage cassette can be configured to removably fit with a port of the exposed panel of the dialysis unit and to fluidly connect the valve to the port of the exposed panel to enable control of the valve.

[0006] In one embodiment, the drainage cassette can include a latch configured to releasably lock the drainage cassette to the exposed panel. For example, the latch can include a handle and a male bayonet-type connector configured to engage a female bayonet-type receiving portion of the panel of the dialysis unit. Thus, the latch can be operated to connect and disconnect the drainage cassette to / from the panel, for example, by inserting the bayonet connector into the receiving portion and turning the handle. By mounting and removing such a cassette, one or more ports, electrical connectors or other components of the drainage cassette provided with corresponding ports, connectors, etc. on the panel can also be connected / separated. For example, a drainage port, a pneumatic valve control port, and an electrical connector connected to one or more sensors of the drainage cassette can be simultaneously connected to corresponding ports / connectors on the panel with a single connection operation, which can include pressing the drainage cassette against the panel and turning the latch handle.

[0007] The drainage outlet port can be in fluid communication with the fluid channel at a location above where the arterial connection port and the venous connection port communicate with the fluid channel, for example, whereby air in the fluid channel can be removed by introducing fluid at the connection port. In one embodiment, the fluid channel has a U-shape, the arterial connection port and the venous connection port are fluid-connected to the fluid channel at the ends of the U-shape, and the drainage outlet port is fluid-connected to the fluid channel at the central bend of the U-shape.

[0008] One or more sensors can be included to detect the characteristics of the fluid in the fluid channel or other locations in the drain cassette. For example, a conductivity sensor can be placed to detect the conductivity of the fluid in the fluid channel, and a temperature sensor can be placed to detect the temperature of the fluid in the fluid channel. The one or more sensors can be coupled to an electrical connector configured to electrically connect the one or more sensors to a corresponding electrical connector of the exposed panel. In one embodiment, the electrical connector and the drain outlet port are configured to simultaneously couple to the corresponding electrical connector and drain connector of the exposed panel of the dialysis unit in a single connection operation. Depending on the configuration, the pneumatic control port coupled to the valve can be configured to removably fit into the control port of the exposed panel and to simultaneously couple to the corresponding control port in the same single connection operation used to connect the drain port and the electrical connector.

[0009] The valve can be configured such that the drain outlet port is permanently open and in fluid communication with the arterial connection port, and can controllably open and close the fluid communication in the fluid channel between the drain outlet port and the venous connection port. Alternatively, the drain outlet port can be permanently open and in fluid communication with the venous connection port, and the valve can be configured to controllably open and close the fluid communication in the fluid channel between the drain outlet port and the arterial connection port.

[0010] In another aspect of the present invention, the blood circuit assembly and the drainage cassette can be engageable with the exposed panel of the diagnostic unit for operation in a dialysis treatment and detachable from the exposed panel for replacement without using tools. Such a configuration enables easy replacement of all blood-contacting components of the dialysis unit, thereby minimizing the risk that substances derived from the blood of a previous patient will come into contact with the treatment components of a subsequent patient, while allowing the dialysis unit to be used for a plurality of different patients (e.g., at a clinical site). For example, the blood circuit assembly may include a pair of pneumatic pumps that circulate blood received from a patient through a circuit including a dialyzer unit and returned to the patient, an air trap configured to remove air from the blood circulating within the circuit, a pair of dialyzer connectors configured to connect to the inlet and outlet of the dialyzer unit, and a pair of blood line connectors including an arterial blood line connector that receives blood from the patient and supplies the blood to the pneumatic pump, and a venous blood line connector that returns the blood to the patient. The pneumatic pump has a pneumatic control port, and the pneumatic control port is configured to be aligned and fitted by engaging a corresponding port located on the exposed panel of the dialysis unit and pressing the control port of the blood circuit assembly onto the exposed panel to engage the corresponding port. Thus, the blood circuit assembly can be relatively easily mounted on and removed from the panel of the dialysis unit. The drainage cassette may include a venous connection port connected to and in fluid communication with the venous blood line connector, an arterial connection port connected to and in fluid communication with the arterial blood line connector, a fluid channel fluidly connecting the venous connection port and the arterial connection port, a drainage outlet port configured to be detachably coupled to the drainage connector of the exposed panel of the dialysis unit and in fluid communication with the fluid channel, and a valve configured to control the flow in the fluid channel. Like the blood circuit assembly, as described above, the drainage cassette can be easily mounted on the panel of the dialysis unit to be controlled by the dialysis unit during the treatment process and removed from the panel for replacement.

[0011] In one embodiment, the flexible tube can fluidly connect a pump, an air trap, a dialyzer connection portion, and a blood line connector of the blood circuit assembly. For example, the flexible tube can fluidly connect the arterial blood line connector to the inlet for the pump cassette, the outlet for the pump cassette to the dialyzer inlet connector, the dialyzer outlet connector to the inlet of the air trap, and the outlet of the air trap to the venous blood line connector. The blood line connector can be configured to be screwed and luer-connected to the patient access and can be configured to be press-fit connected to the drainage cassette connection port. Such a configuration enables easy connection to the drainage cassette and enables connection disinfection. For example, by the press-fit connection to the drainage cassette, the disinfection fluid can be flowed around the patient access connection portion of the connector. The drainage cassette can have the other features described above.

[0012] In another aspect of the present invention, a blood circuit assembly for a dialysis unit includes a pair of pneumatic pumps that circulate blood received from a patient through a circuit including a dialyzer unit and returned to the patient, an air trap configured to remove air from the blood circulating in the circuit, a pair of dialyzer connection portions configured to connect to the inlet and outlet of the dialyzer unit, a pair of blood line connectors including an arterial blood line connector that receives blood from the patient and provides the blood to the pneumatic pump, and a venous blood line connector that returns the blood to the patient, and a flexible tube that fluidly connects the pump, the air trap, the dialyzer connection portion, and the blood line connector. The pneumatic pump can have a pneumatic control port, and the pneumatic control port is configured to be aligned and fitted by engaging the corresponding port located on the exposed panel of the dialysis unit and pressing the control port of the blood circuit assembly mounted on the exposed panel to engage with the corresponding port.

[0013] Also, the pump can be formed by a single integral member that further forms at least partially a plurality of orienting channels for at least a portion of the flexible tube. In one embodiment, the single integral member or other braided tray configuration forms an air trap cavity that receives the air trap. In some configurations, when the blood circuit assembly is mounted on the dialysis unit, the inlet of the air trap is supported by the air trap cavity or other support at a position above the outlet of the air trap. This configuration can make the removal of air from the blood line more effective.

[0014] In another embodiment, the single integral member can form a pneumatic control port for the pump, a concave chamber portion for the pump, chamber portions for a plurality of valves used to control the flow through the pump, an orienting channel for the flexible tube positioned to engage the flexible tube with a closure when the assembly is mounted on the dialysis unit, and / or other features. For example, the braided tray can include a circuit tube engaging member having holes through which respective circuit tubes pass, and the circuit tube engaging member engages with the tubes to allow the circuit tubes to be pulled and stretched so as to engage with the closure of the dialysis unit. For example, by ensuring that various components are properly positioned on the panel of the dialysis unit, forming a plurality of parts of the blood circuit assembly in a single component, and / or accurately orienting the flexible tube, the assembly of the blood circuit assembly can be made easier and more effective.

[0015] In another embodiment, the flexible tube can connect components as follows. That is, the arterial blood line connector can be connected to the inlet for the pump cassette, the outlet for the pump cassette can be connected to the dialyzer inlet connector, the dialyzer outlet connector can be connected to the inlet of the air trap, and the outlet of the air trap can be connected to the venous blood line connector.

[0016] In some embodiments, the blood circuit assembly can include an anticoagulant connection that engages an anticoagulant source and provides anticoagulant into the circuit. For example, an anticoagulant pump that pumps anticoagulant from the anticoagulant source into the circuit can be included, for example, as part of a pump cassette. The anticoagulant connection can include a vial holder and a spike, and the anticoagulant source can be a vial of heparin.

[0017] In another aspect of the invention, a blood circuit assembly engagement device for a dialysis unit includes an actuator mounted on a panel of the dialysis unit adjacent to a plurality of control ports and movable between a holding position and a removal position, a retainer element coupled to the actuator and configured to hold a blood circuit assembly mounted on the panel of the dialysis unit on the panel when the actuator is in the holding position and to release the blood circuit assembly to be removed from the panel of the dialysis unit when the actuator is in the removal position, and an ejector element coupled to the actuator and configured to move the blood circuit assembly away from the panel when the actuator moves from the holding position to the removal position. Such a configuration can make the mounting, holding, and removal of the blood circuit assembly to / from the dialysis unit more accurate and effective. For example, if the retainer element is not positioned in the holding position when the blood circuit assembly is mounted on the panel, the user can easily confirm that the assembly is not properly engaged with the panel. Thus, the actuator can be used to remove the assembly, enabling replacement of the assembly on the panel.

[0018] In one embodiment, the actuator is pivotally mounted on the panel, and the retainer element is fixed to the actuator. The ejector element is pivotable between an inactive position and an ejection position and can pivot based on the movement of the actuator. For example, the actuator can be configured to be moved from the holding position and the ejection position by the user's thumb. In one configuration, a first blood circuit assembly engagement device and a second blood circuit assembly engagement device are provided on the panel. The first engagement device is disposed on a first side of the blood circuit assembly mounted on the panel, and the second engagement device is disposed on a second side of the blood circuit assembly mounted on the panel. The first side and the second side can face each other, whereby the actuators of the engagement devices can be moved by the user's respective first thumb and second thumb. For example, using both thumbs, the user can push the actuators to move the actuators away from each other and move the actuators from their respective holding positions to the ejection positions. The ejector element can be configured to contact a part of the pump chamber, for example, the rear chamber wall of the pump, at the ejection position, and the retainer element can be configured to contact the outer surface of the blood circuit assembly and lock the blood circuit assembly in place when the actuator is in the holding position and the blood circuit assembly is mounted on the panel.

[0019] This specification also describes a closure assembly configured to facilitate opening and closing by closing a flexible tube. In a specific embodiment, the closure assembly is associated with or forms part of a medical infusion device such as a hemodialysis device, a peritoneal dialysis device, a plasma exchange device, etc., and can be controllably and automatically operated to facilitate fluid processing by such devices. The closure assembly can be designed to position and fix the tubing and can include a frame, or a tubing guide, and / or other support mechanisms configured to be attached to or incorporated into the fluid processing assembly of the device of which they are also a part. The closure assembly includes a tubing closure portion, and the tubing closure portion can be a mechanism configured and positioned to apply a force to a tube associated with the closure assembly to close the tube and release the force so that the tube can be opened for fluid flow. The closure assembly and the tubing closure portion can be configured to close a single tube in one embodiment, or multiple tubes, whether the number of tubes is odd or even, in other cases. Some closure assemblies can, in particular, be configured to close two or more pairs of tubes and include a tubing closure portion having separate closure members for closing each of the pairs of collapsible tubes. The closure assembly can include an automatic actuator for operating the tubing closure portion and, in one embodiment, can also include a manual actuator that provides an override function. The closure assembly can include a door designed and positioned to cover at least a portion of the included tubing and the tubing closure portion mechanism. Such a closure assembly can include, for example, a safety mechanism that prevents release of the closing force on the tubing when the door is not in the closed position, and / or a convenience function, such as a retainer mechanism that holds the tubing closure portion in the non-closed position when the door is opened when the tubing closure portion is in the non-closed position.

[0020] In one aspect, various closure assemblies are described for closing at least one collapsible tube of a medical infusion device. In some embodiments, the closure assembly is configured to close at least one pair of collapsible tubes, and for each pair of collapsible tubes, includes a first closure member and a second closure member, such that when the tube is placed in the closure assembly for operation, the first closure member is positioned adjacent to the first collapsible tube of the pair and the second closure member is positioned adjacent to the second collapsible tube of the pair. The first closure member and the second closure member are further positioned adjacent to each other such that a space is formed between the first closure member and the second closure member. These spaces are on the side of each closure member opposite the collapsible tube to which that closure member is adjacent. The closure assembly further includes a spreader portion positioned within the space between the closure members and movable from a first position to a second position, such that movement from the first position to the second position causes the spreader portion to force at least a portion of the first and second closure members to move away from each other to increase the size of the space therebetween, and to force the tube contact portion of each closure member into contact with the collapsible tube to which that closure member is adjacent to close the collapsible tube. The closure assembly further includes at least one actuator configured and positioned to move the spreader portion between the first position and the second position.

[0021] In some embodiments, the closure assembly comprises a frame with a piping guide configured to position at least one collapsible tube and to close the collapsible tube, a piping closure having a closure member mounted on the frame and configured and positioned to controllably close or release the closure of the collapsible tube, a door hingedly mounted on the frame and positioned to cover at least a portion of the collapsible tube and the piping closure when in the closed position and to provide user access to the collapsible tube when in the open position, and a switch configured and positioned to detect when the door is in the closed position and to enable the release of the closure of the collapsible tube by operation of the piping closure only when the door is in the closed position.

[0022] In some embodiments, a closure assembly for closing at least one collapsible tube comprises a piping closure having a closure member configured and positioned to controllably close or release the closure of the collapsible tube, an automatic actuator operably coupled to the piping closure such that, by a substantially linear movement of at least a portion of the piping closure, the closure member moves from a closed position to an unclosed position, and an override mechanism operably coupled to the piping closure such that, upon manual operation of the override mechanism by a user, the closure member moves from the closed position to the unclosed position by a substantially linear movement of at least a portion of the piping closure.

[0023] In some embodiments, a closure assembly for closing at least one collapsible tube comprises a frame with a pipe guide configured to position the collapsible tube, a pipe closure having a closure member mounted on the frame and configured and positioned to controllably close or release the closure of the collapsible tube, a door hingedly mounted on the frame and positioned to cover at least a portion of the collapsible tube and the pipe closure when in the closed position and to provide user access to the collapsible tube when in the open position, and a retainer mechanism configured to be engaged by the door when the door is in the closed position and configured to enable the collapsible tube to be closed or the closure thereof to be released by operation of the pipe closure, and to engage and hold the pipe closure in the unclosed configuration while the door is open when the pipe closure is positioned in the unclosed configuration.

[0024] In another aspect, a method of operating a closure assembly for closing at least a pair of collapsible tubes of a medical infusion device is disclosed. In one embodiment, the method includes moving a spread portion of the closure assembly from a first position to a second position, wherein the spread portion is in a space formed between a first closure member and a second closure member, and the spread portion is forced to move away from each other to increase the size of the space therebetween, and a tube contact portion of each closure member is forced into contact with a collapsible tube adjacent to the closure member to close the collapsible tube.

[0025] Other aspects of the present invention generally relate to hemodialysis and similar dialysis systems. The exemplary embodiments described herein, in one embodiment, include related products, alternative solutions to particular problems, and / or multiple different uses of one or more systems and / or articles. Although the various systems and methods described herein are described in relation to hemodialysis, it should be understood that they are also applicable to other dialysis systems and / or extracorporeal systems capable of treating blood or other body fluids, such as hemofiltration, hemodiafiltration, etc.

[0026] According to one aspect of the present invention, there is provided a housing comprising a portable hemodialysis unit, the hemodialysis unit including a dialyzer, one or more pumps for circulating blood through the dialyzer, a dialysate source, and one or more pumps for circulating dialysate through the dialyzer, and having suitable components for performing hemodialysis. The housing can comprise a housing that supports the components of the hemodialysis unit and has a front panel where a blood circuit connection part and a dialysate fluid connection part are arranged. For example, the front panel can support a blood line connection part for patient blood access, a reagent supply connection part, and a dialyzer connection part for both blood flow and dialysate flow. Thus, in one embodiment, an operator can complete all necessary fluid circuit connections for the blood circuit and reagent supply on the front panel of the housing. The housing can be provided at opposite ends of the front panel with a pair of vertical parallel doors hingedly attached to the housing so that the doors can move between an open position and a closed position. When the doors are in the open position, the operator can access the blood circuit connection part and the dialysate fluid connection part. Further, when the doors are in the closed position, access to the patient access and the dialysate fluid connection part is blocked, and heat inside the housing suitable for disinfection during a disinfection cycle can be retained. For example, at least one of the doors can include a seal for helping to retain heat by resisting air exchange between the inside and outside of the housing when the door is in the closed position and / or for helping to prevent the entry of dust, debris, or other contaminants.

[0027] In one embodiment, each of the vertical parallel doors is attached to the housing through a hinge plate that is pivotally mounted on the door at a first end and pivotally mounted on the housing at a second end opposite the first end. Thus, the door can take two open positions, for example, a first open position where the blood circuit connection part and the dialysate fluid connection part are exposed and the hinge plate is close to the housing, and a second open position where the hinge plate is away from the housing. One or more holding members can be provided to hold the door in the open position relative to the corresponding hinge plate. For example, the holding member can include at least one magnet mounted on the door or the hinge plate that attempts to hold the door in the open position relative to the hinge plate and the housing. Further, one or more holding members can hold the hinge plate in a closed position relative to the housing, for example, a position close to the housing, and / or hold the hinge plate in an open position away from the housing.

[0028] In one embodiment, at least one of the doors can include a container holder that can move between a folded position and an unfolded position, and the container holder is arranged to support a container such as a reagent supply container. Further, or alternatively, one or both of the doors can include a hook that supports a control interface for a hemodialysis unit, such as a remote interface unit connected to the housing by a communication cable. These features make the dialysis unit easier to use by supporting the components in a convenient position.

[0029] In another embodiment, the front panel can include at least one flange portion that supports the blood lines of the blood circuit assembly. For example, the front panel can include several flange portions disposed at the periphery of the front panel, such as the lower corners or the upper edges of the front panel. The blood circuit lines connected to the patient are relatively long (e.g., 3 to 4 feet or more) and can be wound around the periphery of the front panel and held in place by the flange portions. The flange portions can be arranged to support the blood lines and move the door to the closed position without contacting the blood lines, for example, to prevent the blood lines from being pinched at the door hinge points.

[0030] In one embodiment, the blood circuit connection portion of the front panel includes arterial and venous blood line connectors for the blood circuit, and the dialysate fluid connection portion of the front panel includes a reagent supply connection point, a dialyzer dialysate connection portion, and a blood line connection point for connecting the arterial and venous blood lines to the direction - guiding circuit of the dialysis unit.

[0031] The hemodialysis unit can be connected to the housing by a flexible cable and include a control interface configured to enable a user to communicate with the hemodialysis unit. In one embodiment, the housing can include a control - interface mounting area on the housing where the control interface can be mounted. For example, the control interface can include foldable legs or other supports so that it can stand in a substantially vertical orientation on the housing.

[0032] In another embodiment, the housing can include an electronic section that is separated and isolated from a disinfection section that is heated to disinfect components of the hemodialysis unit. For example, the disinfection section can include all of the fluid circuit components of the various parts of the dialysis unit, such as valves, pumps, tubing, and the like. The electronic section can include motors, computers or other data processing devices, computer memory, and / or other temperature-sensitive electronics or other components. By isolating the electronic section (at least to some extent) from the disinfection section, the components within the electronic section are not exposed to the heat or other environmental conditions within the disinfection section, either during the disinfection operation or during other operations.

[0033] According to another aspect of the present invention, a portable hemodialysis system can be configured such that the fluid circuit pump of the dialysis unit is provided by a modular power unit, for example, a unit that can be selectively connected or disconnected from the dialysis unit. As a result, even if the power unit fails, it is not necessary to disable the entire dialysis system. Alternatively, the power unit can be replaced with another power unit to continue the treatment. For example, a modular assembly for a portable hemodialysis system can include a dialysis unit having a housing that houses appropriate components for performing hemodialysis, such as a dialyzer, one or more pumps for circulating blood through the dialyzer, a dialysate source, and one or more pumps for circulating dialysate through the dialyzer. The housing can have a front panel where blood circuit connections and dialysate fluid connections are located. For example, on this panel, an operator can connect patient blood access, connect a reagent supply source, and / or connect a dialyzer. The modular assembly can also include a power unit having a housing for housing appropriate components that provide operating power to the pumps of the dialysis unit. The power unit is selectively connected to the dialysis unit and can supply power to the dialysis unit for the pumps when connected to the dialysis unit, but can be made unable to supply power to the dialysis unit when disconnected from the dialysis unit. The power unit can be selectively connected and disconnected from the dialysis unit by the operation of a single handle. For example, an operator can rotate a single handle or otherwise operate to disconnect the power unit from the dialysis unit. In one embodiment, the dialysis unit and the power unit are each sized and weighted such that they can be carried by a person.

[0034] In one embodiment, the pump of the dialysis unit is a pneumatic pump, and the power unit supplies pneumatic power to the dialysis unit. For example, the power unit can supply air pressure and / or vacuum to the dialysis unit to power the pump. The power unit can include one or more air pressure pumps and / or vacuum pumps, and the dialysis unit can include a plurality of valves for controlling the application of pneumatic power to the pump. To assist in the use of the hemodialysis system at home, the power requirements of the power unit and the dialysis unit are provided by standard household power, such as approximately 110V, 15amp of electricity. The dialysis unit supplies power to the power unit, and the power unit can use that power to generate operating power for the pump.

[0035] According to another aspect of the present invention, the blood circuit assembly for the dialysis unit can be configured to perform the replacement of most or all of the blood circuit components in a single operation. For example, the blood circuit assembly can include a braiding tray, a pair of pneumatic pumps mounted on the braiding tray for circulating blood received from the patient through a circuit including the dialyzer unit and returned to the patient, an air trap mounted on the braiding tray configured to remove air from the blood circulating in the circuit, a pair of dialyzer connectors configured to connect to the inlet and outlet of the dialyzer unit, and a pair of blood line connectors, one inlet blood line connector receiving blood from the patient and supplying the blood to the pneumatic pump, and the other outlet blood line connector returning blood to the patient.

[0036] In one embodiment, an anticoagulant connection is provided for engaging an anticoagulant source and supplying anticoagulant to the blood circuit. For example, the anticoagulant connection can include an anticoagulant pump for pumping anticoagulant from an anticoagulant source, such as heparin, from a heparin vial to the circuit. The anticoagulant connection can include a vial holder configured to hold two or more differently sized vials and a spike passing through the vial. In one embodiment, a pair of pneumatic pumps, the anticoagulant connection, and the anticoagulant pump are part of a pump cassette.

[0037] In another embodiment, the blood circuit assembly can be selectively mounted on or removed from the dialysis unit. To assist in handling the blood circuit assembly, the braiding tray can include a pair of handles configured for a user to grasp. Further, the braiding tray can include an opening proximate each handle to receive a retaining tab on the dialysis unit that engages the blood circuit assembly to hold the blood circuit assembly on the dialysis unit.

[0038] In one embodiment, the inlet blood line connector is connected to the inlet for the pump cassette, the outlet for the pump cassette is connected to the dialyzer inlet connector, the dialyzer outlet connector is connected to the inlet of the air trap, and the outlet of the air trap is connected to the outlet blood line connector. When the blood circuit assembly is mounted on the dialysis unit, the inlet of the air trap can be positioned above the outlet of the air trap, for example, to assist in capturing air circulating within the circuit during treatment. The blood line connectors are configured for a screw-on Luer connection to the patient access and a press-fit connection to the dialysis unit. Such a configuration allows the operator to engage the blood line connector at the patient blood access with a standard Luer connector and more easily connect the blood line connector to the dialysis unit after treatment (e.g., for subsequent disinfection and / or priming of the blood circuit).

[0039] In one embodiment, the braiding tray can include a circuit tube engagement member having holes or slots through which each circuit tube passes. The engagement member can engage each circuit tube to pull and stretch the circuit tube to engage a closure portion of the dialysis unit. For example, the circuit tubes of the blood circuit assembly can include silicone tubes that need to stretch (thereby reducing the diameter) to engage the closure portion. The circuit tube engagement member can resist pulling by the operator on the tube to stretch the tube and position it in engagement with the closure portion.

[0040] According to another aspect of the present invention, a method for replacing a blood circuit assembly of a dialysis unit includes grasping a pair of handles on a braiding tray of the blood circuit assembly mounted on the dialysis unit, separating a locking tab of the dialysis unit from the blood circuit assembly to release the blood circuit assembly from the dialysis unit, and pulling a handle on the braiding tray of the blood circuit assembly to remove the blood circuit assembly from the dialysis unit. Separating the locking tabs can be performed by flexing the locking tabs relative to each other such that each locking tab moves towards the nearest handle. After removing the blood circuit assembly, a replacement blood circuit assembly can be provided, the openings of the braiding tray of the replacement blood circuit assembly can be arranged such that each locking tab is received in each opening, and the braiding tray can be pressed against the dialysis unit such that the locking tabs engage with the replacement blood circuit assembly to attach the replacement blood circuit assembly to the dialysis unit. Mounting the replacement blood circuit assembly can further include connecting a control port on the dialysis unit to a mating port on the assembly such that a fluid control signal is provided to a pump and valves of the blood circuit assembly. Other blood circuit connections can be made, such as inlet and outlet connections for a dialyzer, and a blood line connector can be connected to receive dialysate and send it into the blood circuit.

[0041] According to another aspect of the present invention, an air trap for a blood circuit within a dialysis unit includes a blood inlet supply line, a blood outlet supply line, a container having a generally spherical inner wall, an inlet at an upper end of the container connected to the blood inlet supply line, and an outlet at a lower end of the container connected to the blood outlet supply line. The inlet can be offset from the longitudinal axis of the generally spherical wall such that blood entering the container through the inlet flows around the generally spherical wall within a spiral path. The flow within such a container helps to remove air bubbles from the blood as it flows from the inlet to the outlet, and the removed air remains near the upper end of the container. The inlet port is configured to introduce blood into the container in a direction generally adjacent to the generally spherical inner wall of the container and / or in a direction generally perpendicular to the longitudinal axis of the container.

[0042] In one embodiment, for example, a split-membrane shaped self-sealing port can be placed on the container, and the seal port is configured to introduce fluid into the container and draw liquid from the container by inserting a needleless device through the split membrane. The self-sealing port can be configured to self-clean when a disinfecting solution circulates within the container. For example, the port can be appropriately exposed to the flowing disinfecting solution to remove debris on the port and / or heat the material to achieve the desired disinfection.

[0043] According to another aspect of the present invention, a tube fixation structure of a blood circuit assembly includes a braided tray that supports components of the blood circuit assembly and has a pair of tube engaging members. Each engaging member has a hole, and a pair of patient inlet lines and outlet lines configured to connect to a patient access point for receiving liquid from and / or supplying liquid to a patient, and a pair of stoppers on the patient inlet lines and outlet lines. The patient inlet lines and outlet lines can each pass through the hole of each tube engaging member such that the stopper engages with the tube engaging member. In this structure, the tube engaging member can resist the pulling and stretching of the inlet line and outlet line when engaging the line with the closure. The tube engaging member can be made flexible such that a user can push inwardly on the engaging member to place the inlet line or outlet line within the closure while resisting downward pulling of the line.

[0044] According to another aspect of the present invention, a hemodialysis system includes a dialyzer mount configured to support a plurality of dialyzer units of various sizes and / or shapes and to accommodate various distances between dialysate connectors on the dialyzer units. The dialyzer mount is disposed on the front panel of the dialysis unit and can include a pair of flange portions, each flange portion being configured to engage a dialysate quick-connect fitting connected to a dialysate port of the dialyzer. Each flange portion can also be configured to engage a groove of the quick-connect fitting located between the base of the quick-connect fitting and the sliding element of the quick-connect fitting. For example, the dialyzer mount includes a pair of keyhole mechanisms, each keyhole mechanism having an upper insertion region sized to insert and receive the base of the quick-connect fitting and a lower flange portion having a width smaller than the overall width of the base of the quick-connect fitting and configured to engage the groove of the quick-connect fitting. The lower flange portion can include a pair of opposing flanges that engage the groove to slide the quick-connect fitting along the flange.

[0045] In one embodiment, the lower keyhole mechanism can include an adjustable support that is movable in the vertical direction. For example, the adjustable support is movable along the opposing flanges. Thus, the adjustable support can be fixed at a plurality of different positions on the flange and can support the weight of the dialyzer. In one configuration, the adjustable support includes a "U"-shaped member and at least one wing nut that can be tightened to fix the "U"-shaped member in place.

[0046] According to another aspect of the present invention, a blood line connector for a blood circuit of a hemodialysis unit can make two types of fluid-tight connections, for example, a screw-type connection using a luer connector at patient access and a press-fit connection in the dialysate circuit of the hemodialysis unit. For example, the blood line connector can include a tube connection end configured to engage and seal with a blood circuit tube, a patient access connection end with a frustoconical member having a female screw portion configured to engage with a male screw-type patient access, and a pair of locking arms extending rearward from the frustoconical member. Each of the locking arms can have a finger recess and a barbed portion, and when making a press-fit connection, the barbed portion can be configured to engage with a fitting connector on the dialysis unit to lock the frustoconical member by a sealing engagement with the fitting connector. When the finger recesses are biased toward each other, the barbed portion can be separated from the fitting connector. In one embodiment, the patient access connection end can include a central tube extending from the center of the frustoconical member. The female screw portion of the frustoconical member and the central tube can be configured to fit with a female luer-type patient access connector or other suitable screw-type connection portion.

[0047] According to another aspect of the present invention, a method of operating a dialysis unit includes connecting a blood line connector of an arterial and venous blood line for the dialysis unit to a patient access connector in communication with a patient blood system. In one embodiment, the patient access connector requires a corresponding blood line connector and forms a luer or screw-type connection between the blood line connector and the patient access connector by establishing a threaded engagement with the patient access connector. The dialysis unit can be operated to draw blood from the patient access connector, feed the drawn blood into the arterial blood line, subject the drawn blood to a dialysis process to generate treated blood, and return the treated blood to the patient through the venous blood line and another patient access connector. Thereafter, the blood line connector can be disconnected from the corresponding patient access connector by loosening the screw, and the blood line connector can be connected to an orientation circuit of the dialysis unit. The blood line connector can be connected to the orientation circuit by a press-fit connection having a corresponding connection point on the dialysis unit, for example, by pushing the blood line connector into the connection point to establish a press-fit connection.

[0048] According to another aspect of the present invention, a reagent supply structure for a hemodialysis system can include a connector configured to supply two or more reagent materials used in creating dialysis fluid and configured to assist in preventing the reagent materials from being connected to the wrong port. For example, the reagent supply source includes an E-shaped fork connector having three parallel prongs, two of the outer prongs being disposed in a common plane, the central prong being disposed above the common plane, a first supply line for a first reagent being connected in fluid communication with one of the outer prongs, a second supply line for a second reagent being connected in fluid communication with the other of the outer prongs, a liquid line being connected in fluid communication with the central prong, and a container containing the first reagent having an inlet connected to the liquid line and an outlet connected to the first supply line for the first reagent. The central prong located out of the plane of the two outer prongs helps to ensure that the E-shaped fork connector is connected in only one direction to the dialysis unit, and thus the E-shaped fork connector can assist in preventing improper connection between the first and second supply lines and the dialysis unit.

[0049] In one embodiment, the container contains a bicarbonate material suitable for use in purifying dialysis fluid for a hemodialysis system. The liquid line may be a water supply line that supplies water to the container, mixes the water with bicarbonate (which can be in powder or other solid form), and flows it into the first supply line. The second supply line may have a connector and be an acid supply line that supplies an acid material to the E-shaped cross connector. The reagent source can also include an acid bag spike that detachably engages with the connector of the acid supply line. The acid bag spike includes a spike member and a pair of spring clips at the end of the acid bag spike facing the connector of the acid supply line, and the acid bag spike can be fluidly connected to an acid bag or other acid source.

[0050] According to another aspect of the present invention, a method of operating a hemodialysis system includes providing a dialyzer having a housing that houses suitable components for performing hemodialysis, the housing including a dialyzer, one or more pumps for circulating blood through the dialyzer, a dialysis fluid source, and one or more pumps for circulating dialysis fluid through the dialyzer. The housing can include a housing that supports the components and has a front panel where blood circuit connection portions and dialysis fluid fluid connection portions are made. A reagent source can be provided that includes an E-shaped cross connector, a first supply line for a first reagent fluidly connected and communicating with one of the outer forks, a second supply line for a second reagent fluidly connected and communicating with the other of the outer forks, a liquid line fluidly connected and communicating with the central fork, a container for containing a first reagent having an inlet connected to the liquid line and an outlet connected to the first supply line for the first reagent. By engaging the E-shaped cross connector with the connection point on the front panel of the dialysis unit, the dialysis unit can supply water to the liquid line of the reagent supply and receive the first and second reagents from the first and second supply lines.

[0051] Other advantages and novel features of the present invention will become apparent from the following detailed description of various non-limiting embodiments of the present invention when considered in conjunction with the accompanying drawings. In the event that the present specification and the disclosure incorporated by reference are relative to and / or conflict with each other, the present invention shall prevail. In the event that two or more documents incorporated by reference contain disclosures that are relative to and / or conflict with each other, the document with the later effective date shall prevail.

Brief Description of the Drawings

[0052]

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DETAILED DESCRIPTION OF THE INVENTION

[0053] Aspects of the present invention will be described with reference to the drawings with reference to exemplary embodiments. In the drawings, like reference numerals refer to like elements. The various aspects of the present invention generally relate to new systems such as hemodialysis systems such as hemofiltration systems, hemodiafiltration systems, and plasma exchange systems. Therefore, although the various systems and methods described herein are described in relation to hemodialysis, it should be understood that they are also applicable to other dialysis systems and / or extracorporeal systems capable of treating other body fluids such as blood or plasma.

[0054] As described below, a hemodialysis system typically includes a blood flow path and a dialysate flow path. In such flow paths, the fluid flow does not necessarily have to be linear, and it should be noted that any number of "branch paths" can exist within the flow path through which the fluid can flow from the inlet of the flow path to the outlet of the flow path. Examples of such branches will be described in detail below. In the blood flow path, blood is drawn from the patient and returned to the patient after passing through the dialyzer. The blood is processed by the dialyzer, and waste molecules (e.g., urea, creatinine, etc.) and water travel from the blood through the semipermeable membrane of the dialyzer to the dialysate solvent passing through the dialyzer by the dialysate flow path. In various embodiments, blood can be obtained from the patient through two lines (e.g., an arterial line and a venous line, i.e., a "double-needle" flow), or in one embodiment, blood can be withdrawn from the patient and returned through the same, i.e., the catheter needle (e.g., the two lines or lumens can both be present within the same needle, i.e., can be in the shape of a "double-lumen" flow). In still other embodiments, a "Y-shaped" or "T-shaped" site is used, and blood is withdrawn from and returned to the patient through a connection with one patient having two branch paths (one for the flow path of the withdrawn blood and the other for the flow path of the returning blood, i.e., in the shape of a "single-needle" flow). The patient can be any subject in need of hemodialysis or similar treatment, including non-human subjects such as dogs, cats, monkeys, etc. and humans.

[0055] In the dialysate flow path, fresh dialysate is created and passed through a dialyzer to treat the blood from the blood flow path. Further, the dialysate can be precisely equalized, or in some embodiments, within at least about 1-2% of the blood pressure, for blood treatment within the dialyzer (i.e., equalize the pressure between the dialysate and the blood). In one embodiment, it may be desirable to maintain a large pressure difference (positive or negative) between the blood flow path and the dialysate flow path. After passing through the dialyzer, the used dialysate containing waste molecules (as described below) is discarded by a predetermined method. The dialysate can be recirculated in a "multi-pass" configuration in one embodiment, which can be advantageous for capturing relatively large molecules with low mobility across the dialyzer. In one embodiment, a suitable heater such as an electrical resistance heater can be used to heat the dialysate before treating the blood within the dialyzer. For example, the dialysate can also be filtered using an ultrafiltration filter to remove contaminants, infectious microorganisms, debris, etc. The ultrafiltration filter can have a pore size selected to prevent the passage of species as described above. For example, the pore size can be less than about 0.3 micrometers, less than about 0.2 micrometers, less than about 0.1 micrometers, or less than about 0.05 micrometers, etc. The dialysate is used to extract waste molecules (e.g., ions such as urea, creatinine, potassium, phosphates, etc.) and water from the blood and send them into the dialysate by solute movement associated with osmosis or filtration, and dialysis solutions are well-known to those skilled in the art.

[0056] Dialysate usually contains various ions such as sodium, chloride, bicarbonate, potassium, and calcium at concentrations similar to those in normal blood. In one embodiment, the bicarbonate may have a concentration slightly higher than that in normal blood. Usually, the dialysate is prepared by mixing water from a water supply with one or more components. Here, the one or more components are "acids" (which may include various species such as acetic acid, dextrose, NaCl, CaCl, KCl, MgCl, etc.), sodium bicarbonate (NaHCO3), and / or sodium chloride (NaCl). The preparation of the dialysate, including the use of appropriate salt concentrations, weight osmolarity, pH, etc., is well-known to those skilled in the art. As will be described in detail below, it is not necessary to prepare the dialysate for the same amount of time as the time during which the dialysate is used to treat the blood. For example, the dialysate can be prepared simultaneously with or before dialysis and stored in a dialysate storage container or the like.

[0057] Inside the dialyzer, the dialysate and blood are usually separated by a semipermeable membrane. Usually, the semipermeable membrane is made of polymers such as cellulose, polyaryl ether sulfone, polyamide, polyvinyl pyrrolidone, polycarbonate, polyacrylonitrile, etc., which allow the transport of ions and small molecules (such as urea, water, etc.) during blood treatment but do not allow solute movement associated with bulk transport or filtration. In one embodiment (such as a high-flux dialyzer), larger molecules such as β2-microglobulin may pass through the membrane. Also, in one embodiment, for example, when a hydrostatic pressure difference exists within the semipermeable membrane, ions and molecules may pass through the dialyzer by convection.

[0058] It should be noted that as used herein, "fluid" means all things having the properties of a fluid, including but not limited to gases such as air and liquids such as water, aqueous solutions, blood, dialysate, etc.

[0059] FIG. 1 is a schematic block diagram of a fluid circuit of a hemodialysis system incorporating various aspects of the invention. In the illustrated embodiment, the dialysis system 5 includes a blood flow circuit 141 that withdraws blood from a patient, passes the blood through a dialyzer 14, and returns the treated blood to the patient. A balance circuit or internal dialysate circuit 143 receives dialysate from an ultrafiltration filter 73, passes the dialysate through the dialyzer 14, and receives used dialysate from the dialyzer 14. A directing circuit or external dialysate circuit 142 supplies fresh dialysate to the ultrafiltration filter 73 and receives used dialysate (directed to the drain port 31) from the internal dialysate circuit 143. The directing circuit 142 can also receive water from a water supply source 30 and flow the water into a mixing circuit 25. The mixing circuit 25 creates dialysate using water from the directing circuit 142 and reagent components 49 such as citric acid, salts, and bicarbonate that can be received from a renewable supply source. The mixing circuit 25 can create dialysate during dialysis and / or before dialysis as needed, for example. The new dialysate created by the mixing circuit 25 is supplied to the directing circuit 142, which can then supply the dialysate to the ultrafiltration filter 73 as described above. The directing circuit 142 can include a heater that heats the dialysate to an appropriate temperature and / or heats the fluid within the disinfection system. For example, for disinfection of the hemodialysis system, a conduit 67 (shown in dashed lines) can be connected between the blood flow circuit 141 and the directing circuit 142.

[0060] FIG. 2 is a schematic diagram showing a more detailed circuit configuration for the dialysis system 5 shown in FIG. 1. Of course, FIG. 2 is only one possible embodiment of the general hemodialysis system of FIG. 1, and it should be understood that in other embodiments, other fluid circuits, modules, flow paths, layouts, etc. are possible. Examples of such systems are referred to in the following documents, each of which is incorporated herein by reference in its entirety. That is, U.S. Patent Application No. 12 / 072,908, filed Feb. 27, 2008; U.S. Provisional Patent Application No. 60 / 903,582, filed Feb. 27, 2007; U.S. Provisional Patent Application No. 60 / 904,024, filed Feb. 27, 2007; U.S. Patent Application No. 11 / 871,680, filed Oct. 12, 2007; U.S. Patent Application No. 11 / 871,712, filed Oct. 12, 2007; U.S. Patent Application No. 11 / 871,787, filed Oct. 12, 2007; U.S. Patent Application No. 11 / 871,793, filed Oct. 12, 2007; or U.S. Patent Application No. 11 / 871,803, filed Oct. 12, 2007.

[0061] The blood flow circuit 141 includes an anticoagulant supply source 11 and a blood pump 13 that sends blood from the patient through the dialyzer 14 and returns the blood to the patient. The anticoagulant supply source 11 can be arranged at another appropriate position such as an arbitrary position upstream or downstream of the blood pump 13 although it is not shown in the blood path flowing toward the dialyzer. The balance circuit 143 includes two dialysate pumps 15 that pump dialysate to the dialyzer 14 and a bypass pump 35. The blood flow through the blood flow circuit 141 is synchronized with the dialysate flow in the dialysate flow path in one embodiment. In one embodiment, the dialysate flow entering and leaving the dialyzer 14 and the balance circuit 143 is balanced using the balance chamber of the balance circuit 143. The directing circuit 142 includes a dialysate pump 159 that pumps dialysate from the dialysate tank 169 through the heater 72 and / or the ultrafiltration filter 73 to the balance circuit 143. Also, the directing circuit 142 receives waste liquid from the balance circuit 143 and directs it to the drain port 31. In one embodiment, the blood flow circuit 141 can be connected to the directing circuit 142 through the pipeline 67, for example, for disinfection as described above. The dialysate in the dialysate tank 169 is supplied by the mixing circuit 25. The mixing circuit 25 generates dialysate using water from the water supply source 30 supplied through the directing circuit 142 and dialysate components 49 (for example, bicarbonate and acid). A series of mixing pumps 180, 183, 184 are used to mix various components to generate dialysate.

[0062] Figure 3 is a proximity view of the blood flow circuit 141 of the present exemplary embodiment. During normal operation, blood flows from the patient through the arterial line 203 through the blood pump 13 to the dialyzer 14 (the direction of the flow during normal dialysis is indicated by the arrow 205. However, in some operating modes, as will be described later, the flow may be in a different direction). Optionally, an anticoagulant can be introduced into the blood from the anticoagulant supply source through the anticoagulant pump 80. After passing through the dialyzer 14 and undergoing dialysis, the blood optionally passes through the air trap and / or the blood sample port 19 and returns to the patient through the venous line 204. The pump 13 can include, for example, a pump 23 that is actuated by a control fluid.

[0063] For example, in one embodiment, the blood pump 13 can include two (or more) pod pumps 23. In this example, each pod pump can include a rigid chamber having a flexible diaphragm or membrane that divides each chamber into a pump compartment and a control compartment. Four inlet / outlet valves can be provided for these compartments, two for the pump compartment and two for the control compartment. The valves for the control compartment of the chamber can be bidirectional proportional valves, one connected to a first control fluid source (e.g., a high-pressure air source) and the other connected to a second control fluid source (e.g., a low-pressure air source) or a vacuum source. During operation of the pod pump 23, the fluid valves can be opened and closed to direct the flow of fluid. Non-limiting examples of pod pumps are described in U.S. Provisional Patent Application No. 60 / 792,073, filed Apr. 14, 2006, or U.S. Patent Application No. 11 / 787,212, filed Apr. 13, 2007, each of which is incorporated herein by reference. If there are two or more pod pumps, the pod pumps can be operated in any suitable mode, e.g., synchronously, asynchronously, in-phase, or out-of-phase. For example, in some embodiments, two pumps can be operated out-of-phase to affect the pumping cycle, e.g., while the first pump chamber is being filled, the second pump chamber is being emptied. To impart a desired pumping cycle, any phase relationship between 0 degrees (where the pod pumps are filled and emptied simultaneously) and 180 degrees (where one pod pump is being filled while the other is being emptied) can be selected. A 180-degree phase relationship can create a continuous flow into and out of the set of pod pumps. This can be beneficial, for example, when a continuous flow is desired for use with a double-needle or double-lumen catheter flow. However, for a single-needle / single-lumen flow, it can be beneficial to set a 0-degree phase relationship. In the case of a 0-degree relationship, the pod pumps are first filled from the needle, then carry the blood through the blood flow path, and return the blood to the patient using the same needle.Also, to achieve the push / pull relationship (for hemodialysis or continuous backflush) across the entire dialyzer, in one embodiment, the execution of a phase between 0 degrees and 180 degrees can be utilized.

[0064] An anticoagulant (e.g., heparin or other suitable anticoagulant) can be contained within vial 11 (or other anticoagulant supply sources such as tubes or bags), and the blood flow circuit 141 can comprise a spike 201 (a needle in one embodiment) that can penetrate the seal of the vial. The spike 201 can be made of plastic, stainless steel, or other suitable materials, and in one embodiment may be made of a sterilizable material, for example, the material can withstand sufficient heat and / or radiation during sterilization.

[0065] In one embodiment, the anticoagulant pump 80, which serves as a metering chamber, can be used to control the flow of anticoagulant into the blood circuit. The anticoagulant pump 80 can be a peristaltic pump or a diaphragm metering pump, and / or can be actuated by a control fluid such as air. For example, the anticoagulant pump 80 can comprise a rigid chamber having a flexible diaphragm that divides the chamber into a pump compartment and a control compartment. One valve for the control compartment of the chamber can be connected to a first control fluid source (e.g., a high-pressure air source), and the other valve can be connected to a second control fluid source (e.g., a low-pressure air source) or a vacuum source. The valve for the pump compartment of the chamber can control the flow of anticoagulant into the blood by opening and closing in coordination with the control compartment. In one embodiment, air supplied through filter 81 is introduced into the blood flow path by the anticoagulant pump 80, for example, air can be supplied into vial 11 before or after the anticoagulant is withdrawn from the vial.

[0066] Measurements of the Fluid Management System ("FMS") can be used to measure the volume of fluid pumped through the pump chamber during one stroke of the membrane or to detect air in the pump chamber. The FMS method is described in U.S. Patent Nos. 4,808,161, 4,826,482, 4,976,162, 5,088,515, and 5,350,357, which are hereby incorporated by reference in their entirety. In one exemplary embodiment, the volume of liquid delivered by an anticoagulant pump, a dialysate pump, or other diaphragm fluid pump is determined using an FMS algorithm that utilizes changes in chamber pressure to calculate volume measurements at the end of the fill stroke and the end of the delivery stroke. The difference between the volumes calculated at the end of the fill stroke and the end of the delivery stroke can be used to determine the actual stroke volume. This actual stroke volume can be compared to the expected stroke volume for a particular sized chamber. If the actual and predicted stroke volumes are significantly different, the stroke has not been completed properly and an error message can be generated.

[0067] The blood flow circuit 141 can also include an air trap 19 for removing air bubbles that may be present in the blood flow path. In one embodiment, the air trap 19 can separate any air present from the blood by gravity and / or include ports for sampling the blood.

[0068] FIG. 4 is a close-up view of the balance circuit 143 in the embodiment of FIG. 2. In the balance circuit 143, the dialysate flows from any ultrafiltration filter 73 into the dialysate pump 15. In this embodiment, the dialysate pump 15 includes two pod pumps 161, 162, two balance chambers 341, 342, and a pump 35 that bypasses the balance chambers 341, 342. The balance chambers 341, 342 are composed of rigid chambers having flexible diaphragms that divide the chambers into two separate fluid compartments and are configured to be used such that the entry of fluid into one compartment expels fluid from the other compartment (and vice versa). Non-limiting examples of pumps that can be used as pod pumps and / or balance chambers are described in U.S. Provisional Patent Application No. 60 / 792,073, filed Apr. 14, 2006, or in U.S. Patent Application No. 11 / 787,212, filed Apr. 13, 2007.

[0069] In one embodiment, the equilibration of the flow within the internal dialysate circuit operates as follows. A set of pneumatic valves 211, 212, 213, 241, 242 are controlled and operate synchronously together. Valves 211, 212, 213 are grouped together, and valves 241, 242 are grouped together. Similarly, a second set of pneumatic valves 221, 222, 223, 231, 232 are also controlled and operate synchronously together. Valves 221, 222, 223 are grouped together, and valves 231, 232 are grouped together. At a first point in time, the first set of valves 211, 212, 213, 241, 242 are opened, and the second set of valves 221, 222, 223, 231, 232 are closed. Fresh dialysate flows into the equilibration chamber 341, and used dialysate flows from the dialyzer 14 into the pod pump 161. Since valve 221 is closed, fresh dialysate does not flow into the equilibration chamber 342. As fresh dialysate flows into the equilibration chamber 341, the used dialysate within the equilibration chamber 341 is expelled and exits the equilibration circuit 143 (since valve 223 is closed, the used dialysate does not enter the pod pump 161). At the same time, the pod pump 162 pushes the used dialysate present within the pod pump (through the open valve 213) into the equilibration chamber 342 (valves 242, 222 are closed, ensuring that the used dialysate flows into the equilibration chamber 342). Thereby, the fresh dialysate contained within the equilibration chamber 342 exits the equilibration circuit 143 and enters the dialyzer 14. Further, the pod pump 161 draws the used dialysate from the dialyzer 14 into the pod pump 161.

[0070] When the pod pump 161 and the balance chamber 341 are filled with dialysis fluid, the first set of valves 211, 212, 213, 241, 242 are closed and the second set of valves 221, 222, 223, 231, 232 are opened. While the valve 221 is open, the valve 212 is also open, so fresh dialysis fluid flows into the balance chamber 342 instead of the balance chamber 341. As fresh dialysis fluid flows into the balance chamber 342, since the valve 213 is currently closed, the used dialysis fluid in the chamber is pushed out and exits the balance circuit. Further, since the valve 232 is blocked and the valve 222 is open at this time, the pod pump 162 draws used dialysis fluid from the dialyzer into the pod pump while preventing the used dialysis fluid from flowing into the pod pump 161. Since the valves 232, 211 are closed and the valve 223 is open, the pod pump 161 pushes the used dialysis fluid contained in the pod pump (from the previous step) into the balance chamber 341. Thereby, (since the valve 241 is open and the valve 212 is closed at this time), the fresh dialysis fluid contained in the balance chamber 341 is induced into the dialyzer 14. At the end of this step, the pod pump 162 and the balance chamber 342 are filled with dialysis fluid. Therefore, the state of the system returns to the initial configuration of this description, so the cycle can be repeated to ensure a constant flow of dialysis fluid with the dialyzer 14. In one embodiment, in order to ensure that the balance chamber valves function properly (e.g., open and close), the fluid (e.g., air) pressure applied to the control side of the balance chamber valves is monitored.

[0071] As a specific example, a vacuum (e.g., a 4 psi vacuum) can be applied to the ports of the first set of valves to open them, and a positive pressure (e.g., a 20 psi air pressure) can be applied to the second set of valves to close them (or vice versa). Each pod pump urges the dialysate into one of the equilibrium chambers 341, 342. By pushing the dialysate into a predetermined volume of the equilibrium chamber, the same amount of dialysate is squeezed out by the diaphragm from the remaining volume of the equilibrium chamber. In each equilibrium chamber, a predetermined volume is occupied by fresh dialysate and heads towards the dialyzer, and the remaining volume is occupied by used dialysate coming from the dialyzer. Thus, the volume of the dialysate entering the dialyzer and the volume of the dialysate exiting the dialyzer are kept substantially equal.

[0072] The bypass pump 35 can direct the dialysate flow from the dialyzer 14 through the equilibrium circuit 143 without passing through either of the pod pumps 161, 162. In this embodiment, the bypass pump 35 is a pod pump similar to the above-described one, having a rigid chamber and a flexible diaphragm that divides each chamber into a fluid compartment and a control compartment. This pump may be the same as or different from the other pod pumps and / or metering pumps described above. When control fluid is used to operate the bypass pump 35, the pressure exerted on the outgoing (used) dialysate side of the dialyzer is further reduced, and fluid is further ultrafiltered from the blood in the dialyzer. As a result, net fluid flows out of the patient's blood through the dialyzer and finally to the drain. Such a bypass is effective, for example, in reducing the amount of fluid the patient has, which can increase when the patient cannot excrete excess fluid (mainly water) through the kidneys. As shown in FIG. 4, the bypass pump 35 can be controlled by control fluid (e.g., air) regardless of the operation of the pod pumps 161, 162. With this structure, it is not necessary to operate the dialysate pump out of balance or out of phase with the blood pump to achieve the removal of the above fluid from the patient, and the net fluid removal from the patient can be more easily controlled.

[0073] To balance flow throughout the dialyzer, the blood flow pump, the pumps in the balancing circuit, and the pumps in the directing circuit (described below) can be operated in tandem to ensure that the flow into the dialyzer is approximately equal to the flow leaving the dialyzer. If ultrafiltration is required, the ultrafiltration pump (if present) can be operated independently of some or all of the other blood and / or dialysate pumps to achieve the desired ultrafiltration rate.

[0074] To prevent gassing of the dialysate, the balancing circuit pump can be kept under pressure above atmospheric pressure. In contrast, however, the blood flow pump and the directing circuit pump use pressure below atmospheric pressure to pull the diaphragm towards the chamber wall to complete the filling stroke. Because fluid moves across the semipermeable membrane of the dialyzer and the balancing circuit pump operates at positive pressure, the balancing circuit pump can use information from the blood flow pump to synchronize the balancing circuit chamber's pumping stroke to the dialyzer with the pumping stroke of the blood pump.

[0075] In one embodiment, when operating in such a balancing mode, without pumping pressure from the blood flow pump, the balancing circuit pump diaphragm will push fluid across the dialyzer into the blood and the other pods in the balancing circuit will not fill completely. Therefore, the blood flow pump reports when it is actively pumping a stroke. When the blood flow pump is pumping a stroke, the internal dialysate pump operates. When the blood flow pump is not pumping blood, the valves controlling the flow from the dialyzer to the internal dialysate pump (and other balancing valves grouped with these valves as described above) are closed to prevent fluid transfer from the dialysate side to the blood side from occurring. While the blood flow pump is not pumping, the internal dialysate pump is effectively frozen, and the pumping stroke of the internal dialysate pump will resume once the blood flow pump resumes pumping. The internal dialysate pump fill pressure can be set to a minimum positive value to ensure that the pump operates above atmospheric pressure with minimum impedance. Additionally, the internal dialysate pump delivery pressure is set to the blood flow pump pressure to closely match the pressure on either side of the dialyzer, minimizing flow across the dialyzer during the delivery stroke of the internal dialysate pump.

[0076] In another embodiment, the internal dialysate pump delivers the dialysate to the dialyzer at a pressure slightly higher than the pressure at which blood is delivered to the dialyzer. This results in a clean dialysate in a perfectly balanced chamber being delivered to the dialyzer. On the return side, the internal dialysate pump can fill the used dialysate from the dialyzer and reliably fill the contained dialysate pump chamber at a pressure slightly lower than the outlet pressure on the blood side of the dialyzer. As a result, sufficient dialysate can be ensured to complete the entire process in the equilibrium chamber. The cross-flow of the semi-permeable membrane caused by these pressure differences tends to cancel each other out, and other pumping algorithms attempt to match the average pressures applied to the dialysate side and the blood side of the dialyzer.

[0077] Stagnant blood flow can cause thrombosis, so it is generally beneficial to keep blood flow as continuous as possible during treatment. Also, if the delivery flow rate of the blood flow pump is discontinuous, the balancing pump may pause the process more frequently, resulting in discontinuous and / or low dialysate flow rates. However, the flow through the blood flow pump can be discontinuous for various reasons. For example, to provide a safe pumping pressure for the patient, the pressure may be limited within the blood flow pump, for example, to +600 mmHg and / or -350 mmHg. For example, in the case of double-needle flow, the two pod pumps of the blood flow pump can be programmed to operate with a phase shift of about 180 degrees relative to each other. Without pressure limitations, this phase matching is always feasible. However, to provide a safe blood flow for the patient, these pressures are limited. (Due to small needles, very high-viscosity blood, limited patient access, etc.) If the impedance during the filling process is high, the negative pressure limit may be reached, and the filling flow rate may become slower than the desired filling flow rate. Thus, the delivery process has to wait for the previous filling process to finish, resulting in a temporary stop of the delivery flow rate of the blood flow pump. Similarly, in the case of single-needle flow, the blood flow pump operates at a phase of 0 degrees, and the two pod pumps of the blood flow pump become empty and are filled simultaneously. Once both pod pumps are filled, the volumes of the two pod pumps are delivered. In one embodiment, in a continuous operation, first the first pod pump and then the second pod pump are filled, and then first the first pod pump and then the second pod pump become empty. Thus, the flow in a single-needle or single-lumen structure can be discontinuous.

[0078] One way to control the pressure saturation limit is to limit the desired flow rate to the slowest filling and delivery strokes. As a result, the blood delivery flow rate is slower, but the flow rate is still known and more continuous, allowing for a more accurate and continuous dialysate flow rate. Another way to make the blood flow rate more continuous in a single-needle operation is to use maximum pressure to fill the pod so that the filling time is minimized. Next, the desired delivery time can be set to the time obtained by subtracting the time taken for the filling stroke from the total desired stroke time. However, as the blood flow becomes less continuous, the dialysate flow rate must be adjusted upward during blood delivery to the dialyzer to compensate for the time the dialysate pump is stopped while the blood pump is filling. If this is performed at the correct timing, the average dialysate flow rate over multiple strokes can be matched to the desired dialysate flow rate.

[0079] FIG. 5 is a close-up view of the orientation circuit 142 of the embodiment of FIG. 2. In this embodiment, the orientation circuit 142 can supply dialysate from the dialysate tank 169 to the heater 72 and the ultrafiltration filter 73 through the dialysate pump 159. The heater 72 can be used to warm the dialysate to a temperature such that the blood in the body temperature and / or blood flow circuit is heated by the dialysate and the blood returning to the patient is above body temperature. In one embodiment, the heater 72 is connected to a control system so that inaccurately heated dialysate (i.e., the dialysate is too hot or too cold) is recycled (e.g., returned to the dialysate tank 169) or sent to the drain instead of being sent to the dialyzer. The heater 72 can also be used for disinfection or sterilization in some embodiments. For example, water can be passed through the hemodialysis system and heated using the heater to a temperature that can be used for disinfection or sterilization, such as a temperature of about 70°C, about 80°C, about 90°C, about 100°C, about 110°C, etc.

[0080] The dialysate flow through the diverter circuit 142 can be (at least partially) controlled by the operation of the dialysate pump 159. Also, the dialysate pump 159 can control the flow through the equilibration circuit 143. For example, as described above, fresh dialysate from the diverter circuit 142 flows into the equilibration chambers 341, 342 of the equilibration circuit 143. The dialysate pump 159 can be used as the driving force to cause fresh dialysate to flow into these equilibration chambers. In one embodiment, the dialysate pump 159 includes, for example, a pod pump similar to those described above. The dialysate can also be filtered, for example, using an ultrafiltration filter 73 to remove contaminants, infectious microorganisms, pathogens, pyrogens, debris, and the like.

[0081] The ultrafiltration filter 73 can be disposed at an appropriate position within the dialysate flow path, such as between the diverter circuit and the equilibration circuit, as shown, for example, in the figure, and / or the ultrafiltration filter 73 can be incorporated into the diverter circuit or the equilibration circuit. When an ultrafiltration filter is used, the pore size can be selected to prevent species from passing through the filter.

[0082] In one embodiment, the ultrafiltration filter 73 can operate such that waste from the filter (e.g., the retentate flow) is sent to a waste stream such as the waste line 39 of FIG. 5. In one embodiment, the amount of dialysate flowing into the retentate flow can be controlled. For example, if the retentate is too cold (i.e., the heater 72 is not functioning or the heater 72 has not heated the dialysate to a sufficient temperature), the entire dialysate flow (or at least a portion of the dialysate) can be branched to the waste line 39 and optionally recycled to the dialysate tank 169 using line 48. The flow from the filter 73 can also be monitored for several reasons, for example, using temperature sensors (such as sensors 251, 252) and conductivity sensors (for confirmation of dialysate concentration, such as sensor 253). Examples of such sensors are described below, and further non-limiting examples are referenced by U.S. Patent Application No. 12 / 038,474, filed Feb. 27, 2008.

[0083] Ultrafiltration filters and dialyzers can provide an additional sorting method for removing contaminants, infectious microorganisms, pathogenic bacteria, pyrogens, debris, etc. Therefore, before reaching the patient's blood, any contaminants must pass through both the ultrafiltration filter and the dialyzer. Even if the integrity of either the ultrafiltration filter or the dialyzer is compromised, the sterility of the dialysate can be maintained and contaminants can be prevented from entering the patient's blood.

[0084] The directing circuit 142 can also send the used dialysate from the balance circuit to the drain port, for example, through the waste line 39 to the drain port 31. The drain port may be, for example, a local government drain port or a separate container that holds water (e.g., used dialysate) for proper treatment. In one embodiment, one or more check valves or "one-way" valves (e.g., check valves 215, 216) are used to control the waste stream from the directing circuit 142 and the system 5. Further, in one example, a blood leak sensor (e.g., sensor 258) can be used to determine whether blood is leaking from the dialyzer 14 into the dialysate flow path. Also, a liquid sensor can be placed in the collection tray at the bottom of the hemodialysis unit to indicate a leak of blood or dialysate, or both, from the fluid circuit.

[0085] The directing circuit 142 can receive water from a water source 30, such as a water container like a bag, and / or a device capable of generating water, such as a reverse osmosis device. In one embodiment, the water entering the system can be set to a specific purity, for example, having an ion concentration below a specific value. The water entering the directing circuit 142 can be sent to various locations, for example, the mixing circuit 25 for generating fresh dialysate and / or the waste line 39. In one embodiment, the valves to the drain port 31 and various recycle lines are opened, and the conduit 67 is connected between the directing circuit 142 and the blood flow circuit 141 so that water continuously circulates through the system. When the heater 72 is started, the water passing through the system is continuously heated to a temperature sufficient to disinfect the system, for example.

[0086] FIG. 6 is a close-up view of the mixing circuit 25 in the exemplary embodiment of FIG. 2. Water from the directing circuit 142 flows into the mixing circuit 25 by the action of the pump 180. In this embodiment, the pump 180 includes one or more pod pumps similar to those described above. In one embodiment, for example, a portion of the water is directed through the mixing circuit 25 to the reagent component 49 for use in transporting components such as bicarbonate 28. In one embodiment, sodium chloride and / or sodium bicarbonate 28 is supplied in powder or granular form and mixed with the water supplied by the pump 180. The bicarbonate from the bicarbonate source 28 is sent through the bicarbonate pump 183 to the mixing line 186, and the mixing line also receives water from the directing circuit 142. Acid (which may be in liquid form) from the acid source 29 is also pumped through the acid pump 184 to the mixing line 186. The components 49 (water, bicarbonate, acid, NaCl, etc.) are mixed in the mixing chamber 189 to produce the dialysate, which then exits the mixing circuit 25 and flows to the directing circuit 142. Conductivity sensors 178, 179 are arranged along the mixing line 186 to ensure that each component is added at the appropriate concentration as it is added to the mixing line. Since the volume delivered by the water pump 180 and / or other pumps is directly related to the conductivity measurement, the volume measurement can be used as a cross-check regarding the composition of the produced dialysate. This ensures that the composition of the dialysate maintains safety even if the conductivity measurement becomes inaccurate during treatment.

[0087] FIG. 7 is a perspective view of a hemodialysis system 5 incorporating various aspects of the present invention. According to one aspect of the present invention, system 5 includes a dialysis unit 51 and a power unit module 52 shown joined together. In this embodiment, the dialysis unit 51 has a housing that houses components suitable for performing hemodialysis, such as a dialyzer, one or more pumps for circulating blood through the dialyzer, a dialysate source, and one or more pumps for circulating dialysate through the dialyzer. For example, the dialysis unit 51 can include a mixing circuit 25, a blood flow circuit 141, an equilibration circuit 143, and a directing circuit 142 as described above. The dialysis unit 51 can also include all the blood circuit connections and dialysate fluid connections necessary for the operation of the system 5. Patient access and other connections can be exposed by opening a vertical parallel door 53 through a handle 54 on the front side of the housing of the dialysis unit 51. In this embodiment, the dialysis unit 51 includes a control interface 55 that can be used to control the operation of the dialysis unit 51 (in this embodiment, mounted on the housing by a flexible cable). The control interface 55 includes a display screen with a touch-sensing overlay that enables touch control and interaction with a graphical user interface presented on the screen. The control interface 55 can also include other functions such as push buttons, speakers, a microphone for receiving voice commands, a digital camera, etc. On the back side of the control interface 55, a retractable “kickstand” (not shown) can be provided that allows the control interface 55 to be placed on top of the housing of the dialysis unit 51. By providing the retractable “kickstand”, the control interface 55 is placed in a substantially vertical position so that the display screen can be properly viewed. In other embodiments, the control interface 55 can include a tablet computer or a handheld electronic communication device, both of which can communicate wirelessly with a controller housed within the dialysis unit 51. Examples of wireless communication means can include wireless local area network technologies such as Bluetooth® technology or Wi-Fi®.

[0088] The housing of the power unit 52 can include components suitable for providing operating power to the dialysis unit 51, such as pumps, valves, and other components for providing air / vacuum to the other components of the dialysis unit 51. As used herein, "pneumatic" means using air or other gases to move a flexible diaphragm or other member (note that air is used merely as an example and that in other embodiments, other control fluids such as nitrogen (N2), CO2, water, oil, etc. can be used). As described above, since the pumps and valves of the dialysis unit 51 operate pneumatically, the power unit 52 can provide one or more pneumatic sources for use by the dialysis unit 51. Thus, the dialysis unit 51 does not necessarily have to be configured to generate and / or store the required pneumatic power and can instead rely on the power unit module 52. The power unit 52 can include one or more pneumatic pumps for generating the desired air pressure and / or vacuum, one or more accumulators or other devices for storing pneumatic power, valves, pipelines and / or other devices for controlling the air flow in the power unit 52, and a controller having appropriate components such as a programmed general-purpose data processor, memory, sensors (for detecting, for example, pressure and temperature), relays, actuators, etc.

[0089] In one embodiment, aerodynamic power (e.g., air under appropriate pressure / vacuum) can be supplied to the dialysis unit 51 by the power unit 52 through one or more supply tanks or other pressure sources. For example, if two tanks are used in the power unit 52, one supply tank can be a positive pressure reservoir, which in one embodiment has a set point of 750 mmHg (gauge pressure) (1 mmHg is approximately 133.3 Pascals). The other supply tank can be a vacuum reservoir or a negative pressure reservoir, which in one embodiment has a set point of -450 mmHg (gauge pressure). In order to enable accurate control of the variable valve for the pod pump, this pressure difference can be utilized, for example, between the supply tank pressure and the required pod pump pressure. The limit of the supply pressure can be set based on the maximum pressure plus margin set for the patient blood flow pump in order to provide a sufficient pressure difference for the control of the variable valve. Thus, in one embodiment, the two tanks are used to supply pressure and control the fluid for all functions of the dialysis unit 51.

[0090] In one embodiment, the power unit 52 can include two independent compressors for the supply tanks. The pressure in the tank can be controlled using appropriate techniques such as, for example, a simple "bang-bang" controller (i.e., a controller with two states: on or open and off or closed) depending on the embodiment, or a more high-performance control mechanism. As an example of a bang-bang controller, in the case of the positive tank, if the actual pressure is less than the set point, the compressor for the positive tank turns on. If the actual pressure is greater than the set point, the compressor for the positive tank turns off. The same logic can be applied to the control of the vacuum tank and the vacuum compressor, with the exception that the sign of the set point term is reversed. When the pressure tank is not regulated, the compressor turns off and the valve closes.

[0091] More precise control of the pressure tank can be achieved by reducing the size of the hysteresis band, but as a result, the cycling frequency of the compressor may increase. When very precise control of these reservoirs is required, a bang-bang controller can be replaced with a proportional integral derivative (PID) controller using a pulse width modulation (PWM) signal on the compressor. Other control methods are also possible.

[0092] In other embodiments, other pressure sources can be used. In one embodiment, two or more positive pressure sources and / or two or more negative pressure sources are used. For example, two or more positive pressure sources can be used to supply different positive pressures (e.g., 1000 mmHg and 700 mmHg) available to minimize leakage. For example, a high positive pressure can be used to control a valve while a low positive pressure can be used to control a pump. This helps limit the amount of pressure that can be sent to the dialyzer or patient and prevents the operation of the pump from overwhelming the pressure applied to adjacent valves. A non-limiting example of negative pressure is -400 mmHg. In one embodiment, the negative pressure source may be a vacuum pump and the positive pressure pump may be an air compressor.

[0093] In one embodiment, the power unit 52 comprises a housing capable of accommodating components as shown in FIG. 7a. In this example, the pump and pneumatic storage assembly are configured to fit within the power unit 52 and include a positive pressure pump 60, a negative pressure pump or vacuum pump 61, a high positive pressure reservoir 62, a low positive pressure reservoir 63, a negative pressure reservoir 64, and a dehumidification or "cooler" section 65. The high positive pressure reservoir 62 can store air at a pressure of, for example, about 1000 mHg to 1100 mHg or more, and the low positive pressure reservoir 63 can store air at a pressure of, for example, about 700 mmHg to 850 mmHg. The reservoir 63 can be filled by interposing a pressure regulator (not shown) between the outlet of the pump 60 and the inlet of the reservoir 63 using the pressurized air generated by the positive pressure pump 60.

[0094] A cooler 65 or other suitable dehumidifier can be interposed between the outlet of the positive pressure pump 60 and the inlets of one or more positive pressure reservoirs 62 and / or 63. By dehumidifying the pressurized air, moisture condensation inside the air pressure line or manifold passage and the valves driven by the positive pressure reservoirs 62 and / or 63 can be prevented. As schematically shown in FIG. 7b, the cooler 65 can comprise a metal coil conduit 66 through which the air from the compressor 60 passes and water can be condensed from the compressed air in the compressor 60. The cooling element 67 can separate the compressed air coil from the heat exchanger 68, and through the heat exchanger 68, ambient air can be drawn in by the fan 69, heated, and discharged. The heat exchanger releases heat to the ambient environment, and the water trap 70 separates the condensed water from the compressed air. Then, the dried compressed air can be stored in the reservoir 62 (or stored in the low-pressure reservoir 63 through a pressure regulator), or can be sent to a downstream device 71 such as a pneumatic manifold with valves. The cooling element 67 can be a commercially available electric Peltier element such as the element model C1-34-1604 of Tellurex, Inc. FIG. 7c shows an example of arranging and configuring the cooler 65 to fit within the boundary of the power unit 52.

[0095] Furthermore, the power unit 52 can be selectively connected to the dialysis unit 51 so that, for example, it can be replaced with a different power unit 52. For example, the dialysis unit 51 can be configured to interact with various types of power units 52, such as a power unit 52 that uses electricity to generate pneumatic power or a power unit 52 that uses stored pneumatic power (e.g., pressurized air stored in one or more high-pressure tanks). Thus, the power unit 52 can be replaced with another unit 52 in the event of a failure or other requirements. For example, there may be cases where it is desirable to use the system 5 in an area where noise generation is unacceptable, such as when people nearby are sleeping. In this case, it is desirable to use a power unit 52 that uses stored pneumatic power rather than a unit 52 that generates pneumatic power by operating a pump or other noise-generating device. As shown in FIG. 8, the power unit 52 can be disconnected from the dialysis unit 51 by operating the handle 521. For example, by turning the handle 521, the power unit 52 can be unlocked from the dialysis unit 51, and not only the mechanical connection between the housings but also the power and / or communication connection between the two can be disconnected. An interface (not shown) between the dialysis unit 51 and the power unit 52 allows for the exchange of pneumatic power (from the power unit 52 to the dialysis unit 51), as well as power, control communication, etc. between the units. The dialysis unit 51 can have connection points for power (e.g., standard 115V, 15Amp power in a household electrical outlet), external communication (Ethernet (registered trademark) or any other suitable connection suitable for communication), water supply, etc. The dialysis unit 51 can provide power or other connections to the power unit 52 if desired.

[0096] The dialysis unit 51 can include a controller that controls the flow of the control fluid to various components of the system 5 and performs other desired functions. In one embodiment, the control fluid is held at various pressures within various tubes or conduits. For example, there is control fluid held at a positive pressure (i.e., greater than atmospheric pressure), and there is also control fluid held at a negative pressure (less than atmospheric pressure). Also, in certain embodiments, the controller can have components that are held separate from the various liquid circuits. This configuration has several advantages. For example, in one embodiment, the liquid circuit of the dialysis unit 51 is heated to a sterilization temperature and / or exposed to relatively high temperatures or other harsh conditions (e.g., radiation) in order to perform sterilization, while the electronic components of the controller are not exposed to such harsh conditions and can be held separately by an insulating wall (e.g., a “firewall”). That is, the dialysis unit housing can include two or more compartments, for example, a compartment having electronic components and other components that are sensitive to heat and other conditions, and a compartment having liquid circuit components that are heated or otherwise processed for sterilization.

[0097] Thus, in some embodiments, the system 5 includes a “cold” section (not heated) and a “hot” section that can be heated, for example, for sterilization. The cold section can be insulated from the hot section by an insulator. In one embodiment, the insulator is a molded foamed insulation material, and in another embodiment, it includes any type of insulation such as spray insulation, air gaps, or insulation cut from a sheet, but is not limited thereto. In one embodiment, the cold section includes a circulation system such as a fan and / or a grid through which air can flow in and out of the cold box. In one embodiment, the insulator can be extended to cover access points to the “hot” section such as doors, ports, gaskets, etc. For example, when the “hot” section is sealed, the insulator can, in one embodiment, completely cover the “hot” section.

[0098] Non-limiting examples of components that may be present within the "cold" section include a power supply, electronic components, a power cable, an air controller, and the like. In one embodiment, at least a portion of the fluid that shuttles between the "hot" sections passes through the "cold" section. However, in other cases, the fluid can flow to the "hot" section without passing through the "cold" section.

[0099] Non-limiting examples of components that may be present within the "hot" section include a cassette (if present), fluid lines, temperature and conductivity sensors, a blood leak sensor, a heater, other sensors, switches, emergency lights, and the like. In one embodiment, some electronic components can also be included in the "hot" section. Examples include, but are not limited to, a heater. In one embodiment, in addition to the fluid, a heater can be used to heat the hot box itself. In some embodiments, the heater 72 heats the entire "hot" section until it reaches the desired temperature.

[0100] According to one aspect of the present invention, the housing of the dialysis unit 51 can be provided with a vertically parallel door that can be opened to expose all mechanical interface points for the blood flow circuit connection and the dialysate circuit connection, that is, all connection points for the patient blood connection and the acid / bicarbonate connection that the user must make in order to use the dialysis unit 51. FIG. 9 is a front view of the dialysis unit 51 having a vertically parallel door 53 in a closed state. In this configuration, the door 53 can block access to the connection points for the patient blood connection and the acid / bicarbonate connection and seal the inside of the unit housing to enable heat preservation suitable for disinfection. The seal provided to the door 53 can be made airtight to prevent or substantially suppress air exchange between the internal environment and the external environment of the housing, or it can be made to slightly reduce the quality to such an extent that the disinfection effect can be maintained.

[0101] In this embodiment, the door 53 is connected to the housing of the dialysis unit 51 by a double hinge structure such that the door 53 is opened in two different open states. FIGS. 10 to 13 show the door 53 in the first open state. In this state, the door 53 exposes all user connections for the blood circuit connection part and the dialyzer circuit, including the dialyzer 14 itself and reagent materials such as consumable acid / bicarbonate materials. This position also exposes other functions such as the holder 531 for an acid / bicarbonate container (not shown) and the hook 532 that can be used to hold any suitable element such as the control interface 55, and the control interface can hook its handle on the hook 532 (see FIG. 7 showing the hook 532 at the front of the left door 53 that can be opened to accommodate the control interface 55 or other elements). The holder 531 of this embodiment can be folded from the position shown in the figure (i.e., folded to extend horizontally from the door 53 and inserted into the recess of the door 53). The holder 531 has a "C"-shaped accommodating portion for accommodating and holding the acid / bicarbonate container, but of course it can be of any suitable shape or other configuration.

[0102] Figures 14 to 16 show the door 53 in a second open state in which the hinge plate 533 of each door 53 pivots away from the dialysis unit housing 51 to the outside. In the present embodiment, a hinge plate 533 extending vertically along substantially the entire height of the dialysis unit housing 51 is pivotally attached to the door 53 at a first outer end and pivotally attached to the dialysis unit housing 51 at a second inner end (of course, the hinge plate 533 can be configured differently, for example, it can be arranged and / or positioned at the upper and lower parts of the door 53 as seen in many refrigerator door structures, and each plate 533 can have two or more parts separated longitudinally from each other). A magnet 534 attached to the hinge plate 533 interacts with a corresponding magnet (or other suitable component such as a steel element) attached to the dialysis unit housing 51 so as to hold the hinge plate 533 in the position shown in FIGS. 10 to 13 by attracting the hinge plate 533 towards the dialysis unit housing 51 (of course, the magnet 534 can be arranged on the unit housing and the hinge plate 533 can have a suitable element (such as a steel piece) attached to the magnet 534). Since the door 53 of the present embodiment also includes a magnet attached to the hinge plate 533, when the door 53 is opened to the first state as shown in FIGS. 10 to 13, the magnet interacts with the corresponding magnet in the hinge plate 533 and assists in keeping the door 53 in the open position relative to the hinge plate 533. Further, these magnets assist in maintaining the relative position between the door 53 and the hinge plate 533 when the hinge plate 533 is opened to the second state shown in FIGS. 13 to 16.

[0103] In the present exemplary embodiment, magnets are used as part of the holding member to assist the door 53 and / or the hinge plate 533 in maintaining a specific open or closed state, but other structures of the holding member are also possible. For example, the hinge connection between the door 53 and the hinge plate 533 and / or the connection between the hinge plate 533 and the housing 51 may be a movement stop structure that serves to elastically hold the door 53 or the hinge plate 533 in a specific position relative to other parts (the hinge plate or the housing). In another embodiment, one or more springs can be used to assist in holding the door 53 in an open position relative to the hinge plate 533. In yet another embodiment, the hinge plate 533 may be something that frictionally or statically fits with a portion of the housing 51 that attempts to hold the hinge plate 533 in a closed position (proximate to the housing). Thus, the holding member that serves to hold the door 53 in a specific position relative to the hinge plate 533 and / or serves to hold the hinge plate 533 in a specific position relative to the housing 51 can take one of a number of possible structures.

[0104] According to another aspect of the present invention, when the door is opened towards the dialysis unit housing, all user connections for the blood circuit connection part and the dialysate fluid connection part necessary for the operation of the system 5 are exposed. For example, as shown in FIG. 17, when the door 53 is in the open state (either the first or the second open state), the front panel 511 of the dialysis unit 51 can be exposed. In the present embodiment, the front panel 511 carries several elements or connection points that the user must access. For example, the dialyzer 14 that must be replaced periodically is mounted on the front panel 511. The dialyzer 14 must be connected not only to the blood flow circuit 141 but also to the balance circuit 143. Further, a connection point 512 for the acid / bicarbonate source 49 is arranged at the lower end of the front panel 511. At this connection point 512, the user can connect to the supply source of the consumable reagent component 49 used by the dialysis unit 51 when preparing the dialysate. An occluder 513 is also mounted on the front panel 511. The occluder 513 receives the tubes of the blood flow circuit and controls the open / closed state of the tubes based on the system operation. The function of the occluder 513 is described in detail in U.S. Patent Application No. 12 / 198,947, filed on August 27, 2008 (Attorney Docket No. D0570.70020US00(G28)), and will be described in more detail later. In summary, unless there are system problems such as leaks, pump failures, overpressure situations, etc., the occluder 513 allows the flow to pass through the arterial and venous lines of the blood flow circuit. If there are problems as described above, the occluder 513 automatically closes the blood line to prevent the flow between the patient. A blood line connection point 514 that connects the arterial blood line and the venous blood line 203, 204 of the blood flow circuit 141 to the orientation circuit 142 (as described with reference to FIGS. 2 and 3, the blood flow circuit 141 can be connected to the orientation circuit 142) is exposed on the front panel 511. This connection is usually made at the end of the treatment so that the system can clean and sterilize the blood flow circuit 141. The front panel 511 also has a set of control ports 515 that fit with the corresponding control ports on the blood pump part of the blood flow circuit 141.The control port 515 supplies a controlled level of pneumatic pressure and / or vacuum to control the open / closed state of the valve and to power the pump of the blood flow circuit 141.

[0105] In another aspect of the present invention, FIG. 17A shows a perspective view of a control port assembly 615 that can accommodate a blood pump assembly 13 and can connect to the fluid control ports of the blood pump assembly 13. For example, a control port 616 for controlling the operation of a valve of the blood pump assembly 13 and a control port 617 for controlling the operation of a pump of the blood pump assembly 13 are shown. A latch member or other engaging device can be provided on one or more surfaces of the control port assembly 615 or within the control port assembly 615, or adjacent to or within a portion of the control port assembly 615 at the location of the control port assembly 615 of the front panel assembly 511 to secure the blood pump assembly 13 to the control port assembly 615 (in the illustrated example, the control port assembly 615 can be reversibly mounted to the front panel assembly 511 through a retaining tab 619). Alternatively, or additionally, a separation or other removal function for the blood circuit assembly can be provided to facilitate removal of the blood pump assembly or other portions of the blood circuit assembly from the front panel 511. For example, a pair of cassette latches and removal assemblies can be mounted on both sides of the control port assembly 615. In the embodiment of FIG. 17A, the blood circuit assembly engaging device includes latch or retainer members 618a and 618b pivotally mounted on the sides of the control port assembly 615. Preferably, the pivot connection portions (e.g., pivot connection portion 620) of the latch members 618a and 618b are biased by appropriately positioned springs to rotate the latch members 618a and 618b towards each other and towards the surface of the control port assembly 615, whereby they can maintain contact with an edge or other portion of the blood pump assembly 13 (shown in cross-section in FIG. 17B) mounted on the control port assembly 615. This is clearly shown by FIG. 17B, which is an upper cross-sectional view of the control port assembly 615 on which the blood pump assembly 13 is mounted. The latch member 618b is shown in its normal biased position in FIG. 17B, securing the outer edge of the blood pump assembly 13 in relation to the control port assembly 615.On the one hand, the latch member 618a is shown in a partially retracted position and can partially separate the blood pump assembly 13 from the control port assembly 615. In a fully retracted position (not shown), the latch member 618a or 618b clears the leading edge of the blood pump assembly 13 and allows the blood pump assembly 13 to be removed from or installed or mounted on the control port assembly 615.

[0106] As shown in FIGS. 17A and 17B, in addition to latch or retainer members 618a and 618b that can serve to hold the blood pump assembly 13 in the control port assembly 615, a separation assist member (or ejector element or ejector member) 622a or 622b can also be included to assist the user in separating the blood pump assembly 13 from the control port assembly 615 and lifting it away from the control port assembly 615. The separation assist member 622a or 622b can be pivotally mounted to the front panel assembly 511 at a position suitable for the contact portions 624a or 624b of the separation assist members 622a and 622b to contact the edge of the lower surface 113a of the blood pump assembly 13 and lift it away from the control port assembly 615 when the separation assist member 622a or 622b is rotated outward. The engagement device can include an actuator such as a thumb or finger contact element 626a or 626b that the user can press laterally to pivot the separation assist member 622a or 622b outward and engage the contact portion 624a or 624b with the lower surface 113a of the blood pump assembly 13, thereby actuating the retainer member 618 and / or the ejector element 622. Preferably, a spring 628 can be included near the pivot connection of the separation assist member 622a or 622b and appropriately arranged to bias the separation assist member 622a or 622b to move the contact portion 624a or 624b away from contact with the lower surface 113a of the blood pump assembly 13. Thus, the biasing force from the separation assist member 622a or 622b does not act to push the blood pump assembly 13 away from the control port assembly 615. In another preferred embodiment, as shown in FIG. 17A, the separation assist member 622a or 622b can be pivotally mounted to the latch member 618a or 618b. In this embodiment, the user can engage the separation assist member 622a or 622b with the lower surface 113a of the blood pump assembly 13 and at the same time push the thumb or finger contact element 626a or 626b outward once to separate the latch members 618a and 618b from contact with the front edge or surface of the blood pump assembly 13.Therefore, by pushing one or more actuators such as a single element 626a or 626b outward, the blood pump assembly 13 can be alternately attached and fixed to the control port assembly 615 or separated from the control port assembly 615, facilitating the installation and / or removal of the blood pump assembly 13.

[0107] Figure 17C shows another embodiment of the blood circuit engagement device, which, in this embodiment, comprises a pair of blood pump cassette retainers and an ejector element. In this embodiment, the cassette retainer element 630 comprises a contact member 632 that contacts the ejector (or separation assist) element 634. In the retracted state, the ejector element 634 is disposed in the recessed region 636 of the blood pump pod recess 638 of the control port assembly 640. As the retainer element 630 pivots outward (in the direction of the arrow in Figure 17C), the contact member 632 presses against the proximal end 642 of the ejector element 634, at which time the ejector element 634 rotates about the pivot axis 644, and the distal end 646 of the ejector element 634 rises out of the recess 636 and engages the rigid rear wall of the working chamber of the mounted pump cassette disposed within the blood pump pod recess 638. Figures 17D and 17E show isolated views of the engagement device with the ejector element 634 in the retracted position (Figure 17D) and the extended position (Figure 17E). In Figure 17D, the retainer element 630 is in the holding position, the retainer element 648 is rotated inwardly towards the center of the control port assembly 640, the ejector element 634 is in the retracted position, the proximal portion 642 is raised and the distal portion 646 is pushed down. In Figure 17E, the retainer element 630 is in the release position, the retainer element 648 is rotated outwardly away from the center of the control port assembly 640, the ejector element 634 is in the raised position, the proximal portion 642 is lowered by the contact member 632, and the distal portion 646 rises out of the recess 636 and protrudes the cassette mounted on the control port assembly 640. The thumb rest (actuator) 650 is shaped such that a user can conveniently apply an outward force to release the cassette by placing one thumb on each of the opposing latch members 630 in the completed assembly as shown in Figure 17C. In one embodiment, the retainer element 630 rotates about an axis formed by a pinion 652 and includes a spring 654 biased in the latching or holding direction to help maintain the cassette in a fixed and mounted state on the control port assembly 640.Figure 17F shows a front view of the blood pump cassette 1000 (which is part of the blood circuit assembly), such as the exposed front panel 511, mounted on the panel of the dialysis unit. Figures 17G and 17H show cross-sectional views of the blood pump cassette 1000 along lines 17G-17G and 17H-17H, respectively, with the cassette 1000 properly attached to the control port assembly 640. Figure 17G shows the relationship between the contact member 632, the ejector element 634, and the rigid rear wall 658 of the pump operating chamber of the cassette 1000. The ejector element 634 is shown in a fully retracted position in their respective recessed regions 636 so that the pump cassette 1000 can be fully attached. Figure 17H shows the relationship between the retainer element 648 and the front plate 656 of the cassette 1000. In this case, the retainer element 648 is juxtaposed with the front plate 656 to secure the cassette 1000 onto the control port assembly 640.

[0108] Figure 17I shows a front view of the blood pump cassette of Figure 17F during the process of separating from the panel 511 of the dialysis unit. Figures 17J and 17K show cross-sectional views of the blood pump cassette 1000 with the cassette 1000 partially lifted from the state of being engaged with the control port assembly 640. Figure 17J shows the relationship between the contact member 632, the ejector element 634, and the rigid rear wall 658 of the pump operating chamber of the cassette 1000. In this case, the distal end 646 of the ejector element 634 contacts the cassette 1000 and raises the cassette 1000 from its fully attached position within the control port assembly 640. Figure 17K shows the relationship between the retainer element 648 and the front plate 656 of the cassette 1000. In this case, the front plate 656 has risen above the retaining surface of the retainer element 648.

[0109] On the front panel 511 of FIG. 17, the user control panel 510 is also exposed. The user control panel 510 includes one or more buttons that can provide another way for the user to bypass the graphical user interface on the control interface 55 and control specific functions (e.g., critical functions) during hemodialysis. For example, this can be very important if the control interface 55 fails during a dialysis treatment session. Non-limiting examples of critical functions are the "dialysis stop" or "dialysis pause" commands and the "dialysis solvent injection" command.

[0110] According to the present embodiment and another aspect of the present invention, the blood flow circuit 141 is formed as a blood circuit assembly removable from the front panel 511 of the dialysis unit 51. Since the blood circuit assembly is not mounted on the front panel 511 in FIG. 17, FIG. 17 does not show the arterial and venous lines 203, 204 for the blood flow circuit 141. FIG. 18 shows a front view of the blood circuit assembly 17 of the present embodiment together with the dialyzer 14. The blood circuit assembly 17 includes the various components described above mounted on the blood circuit braiding tray 171, for example, referring to FIG. 3. The arterial and venous lines 203, 204 (including, for example, the length of flexible silicone tubing) terminate at a blood line connector configured to provide a screw-type connection for use with a general patient access point (e.g., a luer-type patient access connector) in addition to a plug-in or press-fit connection with the blood line connection point 514 according to one aspect of the present invention. The arterial line 203 leads to an inlet existing above the blood pump 13 that includes two pod pumps 23, valves, and other components that control blood flow. The blood pump 13 is associated with an air filter 81, an anticoagulant pump 80 (not shown), and an anticoagulant source 11 (such as a heparin vial) (details regarding the blood pump 13 of the illustrated embodiment are referred to in U.S. Patent Application No. 11 / 871,680 filed on October 12, 2007, entitled "Pumping Cassette", U.S. Patent Application No. 11 / 871,712 filed on October 12, 2007, entitled "Pumping Cassette", U.S. Patent Application No. 11 / 871,787 filed on October 12, 2007, entitled "Pumping Cassette", U.S. Patent Application No. 11 / 871,793 filed on October 12, 2007, entitled "Pumping Cassette", and U.S. Patent Application No. 11 / 871,803 filed on October 12, 2007, entitled "Cassette System Integrated Apparatus").The blood output from the blood pump 13 (the outlet is located at the bottom of the pump 13) enters the inlet of the dialyzer 14 (which is at the top of the dialyzer 14), exits the dialyzer (the dialyzer blood outlet is located at the bottom of the dialyzer 14), and flows into the inlet of the air trap 19. The outlet of the air trap 19 is connected to the venous blood line 204. The connections to the inlet blood port and the outlet blood port of the dialyzer 14 are made by typical screw-type connections.

[0111] FIG. 18a shows a perspective view of a blood pump 13 comprising another embodiment of a vial holder or vial carrier 1206 for holding or mounting a vial 11 of a drug 11 (such as an anticoagulant, etc.) on a hollow spike 1208 in fluid communication with a pump 80 (schematically shown in FIG. 3) of the blood pump 13. In this embodiment, the flexible upper arm 1210 serves to hold the body of the vial 11 in place and can flex to accommodate vials of various sizes. The lower arm 1212 serves to align the inverted top of the vial 11 with the spike 1208 so as to prevent the vial 11 from protruding at an angle with respect to the inverted top of the vial 11. Having the top of the vial 11 protrude substantially vertically can serve to avoid leakage of fluid from within the vial 11 around the outside of the spike 1208.

[0112] According to another aspect of the present invention, the air trap 19 is disposed in the blood flow path after the blood exits the dialyzer and before returning to the patient. In one embodiment, the air trap 19 can have a spherical or ellipsoidal container (i.e., a container having a generally spherical inner wall), an inlet port disposed near the top and offset from the vertical axis of the container, and an outlet at the bottom of the container (the vertical axis of the container is disposed in the vertical direction passing through the "upper and lower" poles of the generally spherical container). The inlet port is offset from the vertical axis (in this case, recessed towards the tray 171), and the blood is introduced into the container in a direction substantially perpendicular to the vertical axis of the container and in contact with the spherical inner wall of the container. As the blood is drawn by gravity (e.g., spirally) to the lower end of the container to facilitate removal of air bubbles from the blood, the curved shape of the inner wall of the trap guides the blood to circulate along the inner wall. Air present in the blood exiting the outlet of the dialyzer 14 enters the upper end of the air trap 19 and remains at the upper end of the container while the blood flows out from the lower end outlet to the venous blood line 204. By disposing the inlet port near the upper end of the trap 19, minimal or no air can be left in the container, and the blood can be circulated in the trap (as a "fully open operation" air trap). It is effective that contact between air and blood can be avoided for regular circulation of the blood in the trap. By disposing the inlet port at or near the upper end of the container, the fluid flow through the blood tube can be reversed (i.e., flow from the lower end to the upper end of the trap 19 and out of the inlet port of the trap 19), and most or all of the air present in the trap can be removed from the trap.

[0113] In one embodiment, a self-sealing port, such as a split septum or membrane or other structured self-sealing stopper, is disposed at the upper end of the trap to allow air to be withdrawn from the container (e.g., by a syringe). For example, the blood side of the self-sealing membrane can be disposed substantially flush with the upper inner side of the trap to facilitate cleaning of the self-sealing port during disinfection by reversing the flow in the air trap using, for example, dialysate or other cleaning fluid. Also, the inlet, outlet, and inner wall of the container and the self-sealing port can be configured to substantially eliminate stagnant regions, i.e., regions where blood stagnates or clots are substantially or entirely absent. The self-sealing port can function as a blood sampling site and / or allow introduction of liquids, drugs, or other compounds into the blood circuit. A sealed rubber-type stopper can be used when needle access is contemplated. The self-sealing stopper using a split septum enables sampling and fluid delivery using a needleless system.

[0114] FIG. 19 shows a braiding tray 171 for a blood circuit assembly 17 that does not carry the components of the various blood circuit assemblies 17. According to one aspect of the present invention, the braiding tray 171 includes a handle 172 (in this embodiment, pulled with fingers) that can be grasped by a user when mounting the blood circuit assembly 17 on the front panel 511 / removing the blood circuit assembly 17 from the front panel 511. Inside the handle 172, an opening 173 is provided so that a spring tab on the front panel 511 can pass through the braiding tray 171 and / or the cassette of the blood pump 13 and engage with the blood circuit assembly 17 to hold the blood circuit assembly 17 in place on the front panel 511. According to another aspect of the present invention, the braiding tray 171 includes a blood line engaging member 174 having C-shaped recesses or other holes through which the corresponding blood lines 203, 204 pass (here, "holes" include recesses as shown in FIG. 19, for example, through holes having continuous walls made by drilling, or other suitable openings). More specifically, the blood line engaging member 174 is used when mounting the blood lines 203, 204 on the closure portion 513. In summary, when mounting the blood lines 203, 204 on the closure portion 513, the blood lines 203, 204 must be pulled downward while being horizontally pushed into the slots of the closure portion 513 (so as to reduce the outer diameter of the lines) and stretched. The blood line engaging member 174 functions to resist the downward pulling on the blood lines 203, 204 (for example, each line 203, 204 can be provided with a stop ring on each engaging member 174 so that it cannot be pulled through the recess of the engaging member 174), and to function to allow the user to push the engaging member 174 inward to place the lines 203, 204 in the closure portion slots. Since the engaging member 174 is integrally formed with the braiding tray 171, a "living hinge", that is, a relatively flexible portion of the braiding tray, is disposed between the engaging member 174 and the main body of the braiding tray 171. Due to this structure, the connection portion between the engaging member 174 and the braiding tray main body bends, so that the engaging member 174 can be pushed inward with respect to the braiding tray 171.

[0115] FIG. 20 is a rear view of the blood circuit assembly 17 with the braiding tray 171 removed. This figure shows the rear of the blood pump 13 with the control ports exposed. These control ports mate with corresponding ports 515 on the front panel 511 (see FIG. 17) so that pneumatic control (e.g., appropriate air pressure or vacuum) is applied to the pump and valves to control their operation and the flow through the blood circuit assembly 17. FIG. 20 also shows the displacement of the inlet port of the air trap 19. That is, the inlet port at the upper end of the air trap 19 is located behind the longitudinal axis of the generally spherical container portion of the air trap 19.

[0116] FIGS. 20A and 20B show exploded perspective views of another embodiment of the blood pump cassette 1000. FIG. 20A shows an exploded front perspective view of the cassette 1000 having a rear (operating side) plate 1001, and the rear plate 1001 includes a pipe braiding portion formed integrally with the rear plate from a single piece of material. FIG. 20B shows an exploded rear perspective view of the cassette 1000 of FIG. 20A. The cassette 1000 shown in FIGS. 20A - 20D can be used as an alternative to the cassette 13 of FIG. 18A and the braiding tray 171 of FIG. 19, combining many of the functions of these components and substantially reducing the cost and complexity of manufacturing and assembling them.

[0117] Cassette 1000 includes a rear plate 1001 that forms the rigid outer walls of the operating chambers of various valves and pumps, an intermediate plate 1002 that holds various valve and pump diaphragms and helps form various flow paths in cassette 1000, and a front plate 1003 that forms the rigid outer walls of some of the fluid chambers of the various valves and pumps in cassette 1000. Cassette 1000 optionally further includes a protective cover 1004 that can be attached to the front face side of rear plate 1001. Protective cover 1004 can include a holding arm that can be used to later mount to vial holder 1037, and this holding arm holds the vial. Protective cover 1004 can temporarily hold either an empty or filled vial before inserting the vial into vial holder 1037 for use during a procedure. That is, the vial can be connected to vial holder 1037, and vial holder 1037 has a hollow spike for disposing the vial within vial holder 1037 in fluid communication with fluid port 1038 of front plate 1003. For example, the vial can be filled with an anticoagulant used during dialysis, or the vial can be empty and used during any cleaning and disinfection procedures either before or after a dialysis treatment.

[0118] The cassette 1000 includes fluid flow pumps 1013 and 1014 that move liquid through the fluid flow side of the cassette 1000. That is, the cassette 1000 includes a left pump 1013 and a right pump 1014 that pump a fluid, which can be blood in the case of a hemodialysis device. The pumps 1013 and 1014 (also referred to herein as pod pumps) can be actuated by a control fluid such as air, liquid, gas, or other fluid entering the cassette 1000 from the ports of the rear plate 1001. The left pod pump 1013 includes a rigid chamber wall 1005 formed in the front (or upper) plate 1003, a rigid chamber wall 1008 formed in the rear (or lower) plate 1001, a hole 1006 formed in the intermediate plate 1002, and a flexible membrane 1007 that can flex between the rigid chamber walls 1013 and 1008. The space between the rigid chamber wall 1013 and the flexible membrane 1007 forms the fluid or blood side (i.e., the fluid chamber) of the left pump 1013, and the space between the flexible membrane 1007 and the rigid chamber wall 1008 forms the pneumatic side (i.e., the control chamber) of the left pump 1013. Similarly, the right pod pump 1014 includes a rigid chamber wall 1009 formed in the upper plate 1003, a rigid chamber wall 1012 formed in the lower plate 1001, a hole 1010 formed in the intermediate plate 1002, and a flexible membrane 1011 that can flex between the rigid chamber walls 1009 and 1012. The space between the rigid chamber wall 1009 and the flexible membrane 1011 forms the fluid or blood side (i.e., the fluid chamber) of the right pump 1009, and the space between the flexible membrane 1011 and the rigid chamber wall 1012 forms the pneumatic side (i.e., the control chamber) of the right pump 1014.

[0119] Each of the pod pumps 1013 and 1014 can include a pair of membrane-based inlet / outlet valves having a fluid flow compartment formed from an upper plate 1003 and a control compartment formed from a lower plate 1001. Those valves can be actuated by applying positive or negative fluid (e.g., air) pressure to individual flexible membranes through control ports in the lower plate 1001. The fluid valves can be opened and closed to direct fluid flow when the pod pumps are pumping. Depending on the sequencing in which valve actuation is made in relation to the operation of the pumps associated with those valves, fluid can be pumped in the forward or reverse direction. Non-limiting examples of pod pumps are described in U.S. Patent Application No. 11 / 787,212, filed April 13, 2007, entitled "Fluid Pumping Systems, Devices and Methods," which is incorporated herein by reference. The pod pumps 1013 and 1014 can be operated in any suitable manner by fluid flow in either direction, e.g., synchronously, asynchronously, in phase, out of phase, etc.

[0120] In the case of hemodialysis use, in one embodiment, an anticoagulant (e.g., heparin, or any other anticoagulant known to those skilled in the art) can be mixed with the blood within the blood flow cassette 1000. For example, the anticoagulant can be contained within a vial (or other anticoagulant supply source such as a tube or bag), and the blood flow cassette 1000 can receive an anticoagulant vial with a vial holder 1037 that can penetrate the seal of the vial (in one embodiment, provided with a needle or a hollow spike). The spike can be formed from plastic, stainless steel, or other suitable materials, and in one embodiment can be a sterilizable material, for example, the material may be able to withstand a sufficiently high temperature and / or chemical exposure to sterilize the material. As an example, the spike can be used to penetrate the seal of the vial, whereby the anticoagulant can flow into the blood flow cassette 1000 and be mixed with the blood in the blood flow path. In other cases, the vial can be filled or partially filled with water or dialysis fluid during cleaning, disinfection, or priming operations.

[0121] Using a third pump 1015, which in one embodiment can act as a metering pump, within the cassette 1000, the flow of a drug (such as an anticoagulant) from a mounted vial into the flow path within the cassette 1000 can be controlled. The metering pump 1015 may have the same design as pumps 1013 and 1014 or a different design. For example, the metering pump 1015 can be a peristaltic pump and can be actuated by a control fluid such as air. For example, as shown in FIGS. 20A - 20D, the metering pump 1015 can include a rigid chamber wall 1015 formed within the rear plate 1001, a rigid chamber wall 1018 formed in the intermediate plate 1002 (see FIG. 20B), and a flexible diaphragm 1015 that divides the pod into a fluid compartment or chamber and a control compartment or chamber. Valves 1028, 1029, 1030 can be connected to a fluid flow path that joins the fluid port 1038, the vent port 1019, and the fluid flow paths leading to or from the first or second pump (such as pump 1013 etc.) and the fluid flow paths leading to or from the metering pump 1015 in various combinations. Thus, the flow of a drug (such as an anticoagulant) or other fluid from a mounted vial into the main fluid flow path within the cassette 1000 can be controlled by the metering pump 1015, and periodically, air can be introduced by the metering pump 1015 from the vent port 1019 through the port 1038 into the mounted vial to equalize the pressure within the mounted vial to ambient pressure when the drug or other fluid is withdrawn from the vial.

[0122] The cassette 1000 can also be provided with a vent hole connected to port 1019. Air can be introduced into the flow path of the metering pump 1015 to equalize the pressure in the attached vial with the ambient air. In this case, the valve 1029 closes the flow between the metering pump 1015 and the main flow path of the first pump 1013 (or the second pump 1014). In one embodiment, the metering pump 1015 can also introduce air into the main flow path of the first pump 1013 or the second pump 1014 so that the system controller can control the emptying of the blood or liquid conveyance components of the system.

[0123] The pod pumps 1013 and 1014 are each provided with raised flow paths 1020 and 1021 in the chambers 1005 and 1009. The raised flow paths 1020 and 1021 allow fluid to continue to flow through the pod pumps 1013 and 1014 after the diaphragms (i.e., flexible membranes) 1007 and 1011 reach the end of their stroke.

[0124] The cassette 1000 includes several valves 1022, 1023, 1024, and 1025 formed in the rear plate 1001. The actuating (or pneumatic) sides of the valves 1022 - 1025 and 1028 - 1030 are formed from the lower plate 1001 and have corresponding actuating ports for the control (e.g., pneumatic) fluid to enter or exit. Several diaphragms 1026 and 1027 installed in the intermediate plate 1002 complete the valves, and the diaphragms 1007, 1011, and 1016 complete the pod pumps 1013, 1014, and the metering pump 1015. The metering pump 1015 is completed by the diaphragm 1016. In a preferred embodiment, the valves are pneumatically actuated, and when the valve diaphragm is pulled away from the adjacent hole in the intermediate plate 1002, the liquid is drawn out, and when the diaphragm is pushed towards the hole, the liquid is pushed through. The fluid flow is directed by the appropriate sequencing of the opening and closing of the valves 1022 - 1025 and 1028 - 1030.

[0125] The metering pump 1015 comprises three passages connected to the fluid chamber 1018 formed in the intermediate plate 1002. One passage allows air from the vent hole 1019 to be drawn into the metering pump 1015, the second passage allows air to be pushed into the spike / source container connected to the vial holder 1037, and alternatively draws liquid from the source container or vial, and the third passage allows the liquid from the source container to be pushed by the metering pump 1015 into the main fluid line connected to the first pump 1013 (or pump 1014 in another embodiment). Valves 1028, 1029 and 1030 determine whether the metering pump 1015 moves fluid or air and in which direction.

[0126] Next, referring to FIG. 20C, an internal view of the lower plate 1100 is shown. Inner views of the actuation / air chambers of the pod pumps 1008 and 1012, the metering pump 1015 and the valves 1022, 1023, 1028, 1025, 1029, 1030 and 1024 are shown. The pod pumps 1008 and 1012, the metering pump 1015 and the valves 1022, 1023, 1028, 1025, 1029, 1030 and 1024 are actuated by a pneumatic air source. Now referring to FIG. 20D, the outside of the lower plate 1100 is shown. A source of control fluid (e.g., air under positive or negative pressure) is connected to the outside of this cassette. In one embodiment, the tubes connect to various ports 1031. In other embodiments, the ports 1031 are configured to be plugged into a control port assembly (e.g., control port assembly 615 of FIG. 17A) of the front panel (e.g., front panel 511 of FIG. 17) of the dialysis unit 51.

[0127] Referring now to FIGS. 20A - 20D, the lower plate 1001 incorporates various braiding unit functions. The lower plate 1001 includes an air trap holding member 1032 having tube guides 1033 and 1034 formed therein. The tube guides 1033 and 1034 direct a tube into and out of an air trap disposed within the air trap holding member 1032. The lower plate 1001 also includes additional tube guides 1035 and 1039. The lower plate 1001 also forms a receiving portion 1036 for receiving an electrical connector that can be used in the device to monitor whether an arterial or venous line has become disconnected from the patient during treatment. FIG. 21 is a perspective view of the front panel 511 of a dialysis unit 51 having a blood circuit assembly 17 mounted thereon without a braiding tray 171 (normally, the blood circuit assembly 17 includes a braiding tray 171, but the tray 171 is not shown in this example to more clearly illustrate the components of the front panel 511). At opposite ends of the cassette of the blood pump 13, the front panel 511 has spring tabs 516 that extend forwardly and flexibly with respect to the blood pump cassette and / or the braiding tray 171 to hold the blood circuit assembly 17 in place. The tabs 516 can be provided with prongs or other features that assist in holding the blood circuit assembly 17 in place. The spring tabs 516 are bent outwardly to release the hold on the blood circuit assembly 17 and allow removal. However, if no outward force is applied to the spring tabs 516, the tabs 516 remain engaged with the blood circuit assembly 17. FIG. 22 is a front view of the front panel 511 including the braiding tray 171 of the blood circuit assembly 17. To remove the blood circuit assembly 17 from the front panel 511, the user places a thumb on the inside of the spring tab 516 (the side closest to the blood pump 23), bends the spring tab 516 outwardly away from the pump 23, and at the same time places an index finger behind the handle 172. This causes the spring tab 516 to release the blood circuit assembly 17, for example, separating the prong of the tab 516 from the blood pump 13 and / or the braiding tray 171.Of course, to remove the blood circuit assembly 17, other connections such as the connection to the dialyzer 14 and the blood line connection point 514 must be removed, and the lines 203, 204 must also be removed from the closure 513. When mounting the blood circuit assembly 17 on the front panel 511, for example, the spring tabs 516 are aligned so as to pass through the openings 173, and the braided tray 171 can be properly positioned by grasping the handle 172 so that the control port of the cassette of the blood pump 13 is aligned with the corresponding port 515 on the front panel 511. Thereafter, the blood circuit assembly 17 is simply pushed into place, and the spring tabs 516 engage with the braided tray 171 and / or the blood pump cassette. Next, other connections such as the connection to the dialyzer 14 and the attachment of the blood lines 203, 204 to the closure 513 can be made.

[0128] FIG. 21 also shows slots 517 that hold the blood lines 203, 204 for leading into the closure 513. The slots 517 form a passage that is slightly smaller than the outer diameter of the blood lines 203, 204 so that the lines 203, 204 remain within the slots 517 after placement within the slots. This aids in ensuring proper association of the lines with the closure 513. Once the blood circuit assembly 17 is mounted on the spring tabs 516, the user can engage the blood lines 203, 204 with the slots 517 by extending the lines 203, 204 downward (with the engagement members 174 on the braided tray 171 engaging a stop ring or other feature on each line 203, 204 and resisting downward pull). The lines 203, 204 are flexible and can be pushed into place by pushing the engagement members 174, which bend inwardly with respect to the braided tray 171, inwardly. The lines 203, 204 can then be advanced through the closure 513.

[0129] According to another aspect of the present invention, the front panel 511 has a blood line wrapping function on the outer periphery of the front panel 511. In the present exemplary embodiment, the front panel 511 has flange portions 518 along the upper edge and the lower corners of the front panel 511. Therefore, the user can wind the blood lines 203, 204 around the outer periphery of the front panel 511 by arranging the lines 203, 204 in the passage formed by the flange portions 518. The lines 203, 204 can be wound clockwise from a location near the lower end of the dialyzer 14 to a location near the lower right corner of the front panel 511. Next, the blood lines 203, 204 are connected at the blood line connection point 514, and for example, the fluid circulated through the blood lines 203, 204 can be disinfected. As a result, the blood lines 203, 204 are properly held on the front panel 511, allowing easy access to other components on the front panel 511, and the user can close the door 53 with little concern about whether the blood lines 203, 204 are pinched between the door 53 and the dialyzer unit housing 51. Alternatively, the blood lines 203, 204 can first be connected at the blood line connection point 514 and then wound clockwise from a location near the lower end of the dialyzer 14 to a location near the lower right corner of the front panel 511. Thereby, the blood lines can be ensured to be properly distributed along the flange portion 518 and reach the connection point 514. As an aid to holding the blood lines 203, 204 at a desired position away from the hinge plate 533 and other potentially pinched locations, vertical fences 519 can also be provided on the left and right sides of the front panel 511.

[0130] In another aspect, as shown in FIG. 21A, another embodiment of the front panel assembly 811 can include a modular drain assembly (or drain cassette) 815 having a connection point 814 that can connect arterial and venous blood lines. As shown in FIG. 5A, the drain cassette 815 includes a common passage to the drain line 31 for both the arterial and venous blood lines during priming, washing, and disinfection operations. Water, dialysis solution, or other fluid can be introduced into the blood path of the dialysis system 5 through the semipermeable membrane of the dialyzer 14 to expel air from the blood path and prime the blood path, or to wash and disinfect the blood path. The drain cassette 815 can optionally include valves in one or both of the arterial or venous blood paths. In one embodiment, an electronically controlled valve 831 within or near the modular drain cassette 815 of the venous line enables the blood pump of the blood pump cassette 13 to sequentially fill or empty the arterial line while the valve 831 of the venous line is closed, and then fill or empty the arterial line when the valve is open. In this way, air or contaminants in the arterial line are forced to the drain outlet of the drain cassette 815 rather than into the venous tubing. Alternatively, the valve 831 can be arranged to control the flow between the arterial line and the drain outlet, for example, so that the contents of the venous line can be forced towards the drain outlet rather than into the arterial line. The drain cassette 815 can also optionally include conductivity and / or temperature sensors 834, 835. The temperature sensor can be used to monitor, for example, the temperature of the fluid circulating through the blood lines during thermal disinfection. The conductivity sensor can be used to monitor, for example, the conductivity of the water or dialysis solution circulating through the blood lines during a urea or sodium clearance test of the dialyzer. The electronically controlled drain control valve 207 can be located at the drain outlet of the drain cassette 815 or (as shown in FIG. 5A) outside the drain cassette 815. The drain control valve 207 can be useful, for example, when heated water or chemical disinfectant is circulating within the blood circuit components of the dialysis unit 51.The drain cassette 815 can be configured to facilitate connection to and disconnection from the front panel 511 or 811 of the dialysis unit 51. The drain cassette 815 can include a single-handle operation latch (such as a bayonet connection, etc.) that fixes the drain cassette to the front panel by turning a handle.

[0131] FIG. 21A also shows another embodiment of the blood pump cassette and the braiding tray assembly. In some embodiments, the braiding tray 822 can be incorporated into the pneumatically actuated plate (or rear plate) of the blood pump cassette 824. FIG. 21B shows the front panel assembly 811 from which the upper and intermediate plate components of the blood pump cassette 824 have been removed for clarity. In this example, the braiding tray 822 and the rear plate 816 of the blood pump cassette 824 are combined into a single molded part. In this example, the air trap 819 is supported by an extension of the braiding tray 822 and is positioned at a vertically elevated position compared to the embodiments shown in FIGS. 19 and 29. By moving the air trap to a higher position relative to the closure 813 or the in-line air detector 823, the ability of the blood pump to draw air bubbles present in the venous tubing into the air trap 819 during the reverse flow procedure can be increased. For example, the inlet of the air trap 819 can be supported by the braiding tray 822 at a position above the outlet of the air trap when the blood circuit assembly is mounted on the dialysis unit. Additionally or alternatively, the inlet and / or outlet of the air trap can be supported by the braiding tray at a position above the highest point of the flexible tubing extending from the outlet of the air trap to the closure position. Such an arrangement can help drive the air in the venous tubing into the air trap 819.

[0132] In another aspect of the present invention, a modular drain cassette having a function of monitoring and discharging a fluid (such as water or a dialysis solution) flowing through the blood circuit of the dialysis unit 51 can be included. The blood circuit includes a blood pump, a blood flow compartment of a dialyzer, an air trap, and arterial and venous blood tubes. As shown in FIG. 5A, when not connected to a patient, the arterial and venous blood tubes can be connected to a drain chamber / air trap 4703 that ultimately leads to the drain line 31. This connection allows, for example, heated water to be circulated for cleaning and disinfecting the blood circuit compartment, for determining the clearance characteristics of the dialyzer, or for priming the blood circuit with a dialysis solution. In one aspect of the present invention, the drain cassette 815 includes a drain chamber / air trap 4703, valves 831 for one or both of the arterial and venous blood lines, a check valve 836 for the drain line, and temperature and conductivity sensors 834, 835 within one modular component that can be easily connected to or disconnected from the front panel of the dialysis unit 51. As shown in FIG. 21A, in one embodiment, the arterial and venous blood lines can be connected to the drain cassette 815 through connection points 814 on the front panel 811. The drain cassette 815 can include a channel or chamber that merges the fluid flows from the venous and arterial blood lines and exits to the drain line 31 through a common outlet.

[0133] As described above, the drain cassette 815 can optionally include a valve 831 in the venous line (or alternatively in the arterial line, or in both lines). In a preferred embodiment, the valve 831 is a pneumatically operated diaphragm valve, which is actuated under the control of an electronic controller by an electromechanical valve piped to a pneumatic source. The drain cassette 815 can also optionally include conductivity and thermal probes 834, 835 in the fluid flow channels or chambers within the housing of the cassette 815. In a preferred embodiment, the drain outlet port, the pneumatic control port, and the electrical connections for the conductivity and thermal sensors comprise mating connectors, one member of each pair being rigidly attached to the housing of the drain cassette 815 and the other member of each pair being rigidly attached to the front panel 811 of the dialysis unit 51 so that the user can quickly and easily mount or remove the drain cassette 815 from the front panel 811. Similar to the other blood circuit components of the front panel 511 or 811 (including the dialyzer 14, the blood pump cassette 13 or 824, the air trap 19 or 819, and the arterial and venous blood lines), the drain cassette 815 can be configured to be easily removable from the dialysis unit 51.

[0134] FIG. 31 shows an exemplary modular drain cassette 815. In this figure, the fascia 825 of the drain cassette 815 includes markings identifying the arterial and venous line connection points 814. The handle 821 in front of the fascia 825 can be grasped with one hand and rotated to engage or disengage the drain cassette 815 from the front panel 811. Blood line connectors 802 for each of the arterial and venous blood lines are shown engaged within their respective connection ports or connection points 814 of the drain cassette 815.

[0135] Figure 32 shows the drainage cassette 815 in an exploded view together with the decorative plate 825 in front of the front wall 826 of the drainage cassette 815. In this example, the front wall 826 is formed by sealing the front wall for the common channel or chamber 827 of the housing 828 of the drainage cassette 815. The common outlet 829 from the channel 827 to the drainage line is equipped with a fluid connector 830 mounted on the rear wall of the housing 828, and the fluid connector 830 can optionally include a one-way check valve (such as a duckbill valve, etc.) so that the fluid in the drainage line does not re-enter the channel 827. A mating connector 830a is mounted on the front panel 811, which is connected to a fluid line that ultimately leads to the drainage port. The outlet 829 is preferably located at a higher position than any of the fluid connection points 814a and 814b in order to trap and ultimately expel air that may be present in the arterial or venous blood lines when connected to the drainage cassette 815. In this regard, the fluid channel 827 can have a U-shape, and the venous and arterial blood line connectors 802 are fluidly connected to their respective connection ports 814a, 814b at the ends of the U-shape, and the drainage outlet port 829 is located at the bend of the U-shape. A valve 831 may be present in one or both of the fluid channel portions of the channel 827 leading from the connection points 814a and 814b. Thus, the valve can controllably open and close the fluid communication in the channel 827 between the connection port 814 and the drainage outlet port 829. In an embodiment where only one valve 831 is provided in the channel 827, the flow between one connection port 814 and the outlet drainage port 829 can be controlled by the valve, while the fluid communication between the other connection port 814 and the drainage outlet port 829 can be permanently open. In the illustrated example, a pneumatically actuated diaphragm valve 831 mounted on the rear part of the housing 828 is disposed over a portion of the channel 827a leading to the venous blood line connection point 814a. A mating pneumatic connector 831a mounted on the front panel 811 supplies positive or negative pneumatic pressure to the valve 831 to actuate the valve, the pneumatic line extending from the pneumatic distribution module to the front panel 811, or the manifold located in the rear part of the dialysis unit 51.Both connectors 830 and 831 can be configured to form a radial sealing engagement with the mating connectors 830a and 831a of the front panel 811 (e.g., using an elastomeric O-ring) so that the drain cassette 815 can be inserted into or removed from the front panel 811 relatively easily. Similarly, an electrical connector 833 can be mounted on the rear wall of the housing 828 for making an electrical connection outside the channel 827 with a temperature and / or conductivity probe disposed within the channel 827. The electrical connector 833 can be configured to form a keyed connection with the mating electrical connector 833a of the front panel 811 to facilitate engagement and separation of the connectors when the drain cassette 815 is installed in or removed from the front panel 811. In some embodiments, the connection to each of the connectors 830, 831, and 833 on the panel 511, i.e., the outlet drain port connector, the valve control port connector, and the electrical connector, can be made essentially simultaneously and / or in a single operation, e.g., by pushing the drain cassette 815 into place on the panel 511.

[0136] FIG. 33 shows a perspective view of the front wall 826 of the drain cassette. In the front wall 826 of the drain cassette, an electrical connection between the probes 834 and 835 and the connector 833 is shown. In this example, the probe 834 comprises one of a thermistor and a pair of conductivity sensors that extends into the channel 827 for detecting both fluid temperature and conductivity. The probe 835 similarly extends into the channel 827 as the second probe of the pair of conductivity sensors that extends into the channel 827.

[0137] FIG. 34 shows the main housing 828 of the drain cassette 815, with the front wall 826 removed for clarity. The heat and / or conductivity probes 834 and 835 are shown to illustrate their positioning in the portion 827b of the fluid flow channel 827 (each probe is installed sealed to the front wall 826 but has an elongated element that penetrates the front wall 826 so as to be present in any portion of the fluid channel 827). The electrical connector 833 is shown positioned in the region of the housing 828 outside the channel 827. In one embodiment, a check valve such as the duckbill valve 836 can be mounted within the drain connector 830 (shown in FIG. 32).

[0138] FIG. 35 shows a rear perspective view of the drain cassette 815. The male fluid connector 830 is configured to connect to the mating connector 830a of the front panel 811, which is connected to the drain line. The male pneumatic connector 831 is configured to connect to the mating connector 831a of the front panel 811, which is connected to the pneumatic line. The male electrical connector 833 is configured to connect to the mating connector 833a of the front panel 811, and the mating connector 833a provides an electrical connection from the heat and / or conductivity sensor within the housing 828 to the system controller in the rear portion of the dialysis unit 51. The latch member 837 connected to the handle 821 is configured to be inserted into the keyhole of the front panel 811 to engage and lock the drain cassette 815 to the front panel 811.

[0139] FIG. 36 shows the front panel 811 with the drain cassette 815 removed. The drain cassette recess 838 is configured to receive the drain cassette 815. The user only needs to align the drain connector 830, the pneumatic valve connector 831, and the electrical connector 833 of the drain cassette 815 with their mating connectors 830a, 831a, and 833a on the front panel 811, and push the cassette 815 into place to make the necessary pneumatic and electrical connections. The latch member 837 of the handle 821 of the drain cassette 815 is inserted into the keyhole 837a, and the handle 821 can be rotated 1 / 4 or 1 / 2 turn to lock the drain cassette 815 within the recess 838, thereby achieving the front panel configuration as shown in FIG. 21B.

[0140] Due to the modular function of the drain cassette 815, advantageously, the user can easily install and remove substantially all of the blood-bearing components of the dialysis system (except for the distal portion of the drain line 31 in one embodiment). Thus, the dialysis unit 51 can be used by more than one individual simply by replacing the blood-bearing components (such as the blood circuit assembly and the drain cassette), with each set assigned to an individual user. The microbiological barrier enabled by the dialyzer semipermeable membrane, the ultrafiltration filter for the incoming water or dialysate within the dialysate side circuit, and the dialysate side disinfection treatment between each use of the dialysis unit 51 allows the dialysate side components to be reusable among different users. The modular drain cassette 815, together with other modular blood circuit components, enables the dialysis unit 51 to be conveniently used in a multi-user clinical setting as well as in a single-user home environment.

[0141] According to another aspect of the present invention, the front panel 511 (or other suitable component) of the dialysis unit 51 can be configured to accommodate dialyzer units 14 of various sizes and / or shapes. Different dialyzers can be specified to provide different treatment conditions for different patients, or in one embodiment, for the same patient over a long period of time. Thus, the dialysis unit 51 is preferably configured to operate with a plurality of different types of dialyzers 14. Often, if the dialyzer 14 is different, the dimensions such as the overall diameter and / or length of the dialyzer unit will be different. In the exemplary embodiment shown in FIG. 23, the front panel 511 includes a dialyzer mounting platform having a pair of "keyhole" features 520 configured to engage respective dialysate quick-connect fittings on the dialyzer 14. Each keyhole mechanism 520 includes an upper insertion region 520a sized to accommodate a portion of the quick-connect fitting and a lower flange portion 520b that is narrower than the overall diameter of the quick-connect fitting and engages the groove region of the quick-connect fitting. To assist in understanding these features, FIG. 24 shows a dialyzer 14 with quick-connect fittings 14a attached to the dialysate inlet and outlet ports of the dialyzer 14 (the blood inlet and outlet ports are located at the upper and lower ends of the dialyzer 14 shown in FIG. 24). The quick-connect fittings 14a shown are of a standard type, and many, but not all, dialyzers 14 are configured with dialysate inlet / outlet ports that engage a standard quick-connect fitting 14a. Each quick-connect fitting 14a includes a sliding element 14b that is moved to the right (as shown in FIG. 24) relative to a base 14c to engage the fitting 14a with the dialysate port on the dialyzer 14. When the sliding element 14b is moved to attach the fitting 14a to the dialyzer 14, a groove 14d is closed. However, when the fitting 14a is properly positioned at the inlet / outlet port of the dialyzer 14, the sliding element 14b is released and a spring (not shown) moves the sliding element to the left as shown in FIG. 24 to reset the groove 14d to the state shown in FIG. 24. Thus, when the quick-connect fitting 14a is properly engaged with the dialyzer 14, the groove 14d is present as shown in FIG. 24.

[0142] To attach the dialyzer 14 to the keyhole mechanism 520, the quick-connect fittings 14a are partially inserted into the upper and lower keyhole mechanism upper insertion regions 520a such that the grooves 14d of each quick-connect fitting 14a are arranged alongside the flange of the lower flange portion 520b of the keyhole mechanism 520. (Note that the upper insertion region 520 of the lower keyhole mechanism 520 can be made longer than that shown in FIG. 23 so as to accommodate a wider range of dialyzer lengths.) When the groove 14d is aligned with the flange, the dialyzer 14 can be lowered so that the quick-connect fitting 14a is completely received in the lower flange portion 520b of the keyhole mechanism 520.

[0143] According to another aspect of the present invention, one or both of the keyhole mechanisms 520 are adjustable such that the weight of the dialyzer 14 is shared by both lower flange portions 520b of the keyhole mechanism 520. For example, in the illustrated embodiment, the lower keyhole mechanism 520 has a portion of the lower flange portion 520b that is adjustable in the vertical position relative to the upper keyhole mechanism 520. Thus, since this portion of the lower flange portion 520b is adjustable in the vertical position, with the upper quick-connect fitting 14a supported by the flange portion 520b of the upper keyhole mechanism 520, the movable portion of the flange portion 520b of the lower keyhole mechanism can be moved, for example, upward, so that the lower quick-connect fitting 14a can also be supported by the flange portion 520b. Therefore, the weight of the dialyzer 14 can be shared by both keyhole mechanisms 520. The flange portion 520b can be made adjustable in any suitable manner. In the present embodiment, the flange portion 520b has a "U"-shaped member 520c that is slidable vertically along the vertical flange and can be fixed in place by tightening a set of butterfly screws. The "U"-shaped member 520c can engage the quick-connect fitting 14a such that the "U"-shaped member 520c supports (at least partially) the weight of the dialyzer 14.

[0144] In the above-described embodiment, the dialyzer 14 is supported by the keyhole mechanism of the front panel 511, but the support structure for the dialyzer can also be configured in other ways. For example, the upper insertion region 520a is not necessarily required. As an alternative, only a flange portion (for example, in the shape of a "U" shaped flange having opposing flange portions) can be provided to engage with the dialyzer quick-connect fitting. The flange portion can be offset from the front surface of the front panel 511 to provide a gap for the fitting, and the flange portion can be engaged with the groove of the quick-connect fitting. Further, the flange portion does not necessarily need to be provided in the vertical direction as shown, and can be angled from the vertical direction and, for example, oriented horizontally. The flange portion can have a function of preventing movement, catching, or other functions that assist in holding the dialyzer in place.

[0145] According to another aspect of the present invention, a bicarbonate, an acid and / or other reagent sources can be selectively associated with a dialysis unit. As described above, the dialysis unit 51 requires a supply of specific chemicals that produce the dialysis fluid and / or other materials necessary for system operation. FIG. 25 shows a reagent source 49 used to supply an acid, bicarbonate and / or other materials to the dialysis unit 52 (FIG. 21 shows the reagent source 49 mounted at the acid / bicarbonate connection point 512 on the front panel 511). The reagent source 49 of this exemplary embodiment includes an E-shaped fork connector 491 configured to fit with the acid / bicarbonate connection point 512. Similar to other connections made by the user on the front panel 511, such as the blood line connection at the connection point 514, the mating connectors can be color-coded or otherwise marked to ensure proper connection. For example, the E-shaped fork connector 491 and the acid / bicarbonate connection point 512 can be orange, the arterial line 203 at the connection point 514 and its mating connection can be red, and the venous line 204 at the connection point 514 and its mating connection can be blue. Extending from the E-shaped fork connector 491 are a bicarbonate supply line 492, a water supply line 493, and an acid supply line 494 (see FIG. 6 and the related explanation regarding the functions of these lines). The water supply line 493 supplies water to the bicarbonate source 28 (in this embodiment, a 750 g Altracart Bicarbonate cartridge (#500750A) sold by Baxter International Inc. that contains a powdered bicarbonate material, but any suitable source may be used). The bicarbonate source 28 supplies bicarbonate to the dialysis unit 51 through the bicarbonate supply line 492. In this embodiment, the acid supply line 494 is connected to an acid bag spike 495 that can be used to pierce an IV-type bag or other container and extract the appropriate acid therefrom. In this embodiment, the acid bag spike 495 includes a spike member 495a and a pair of spring clips 495b.The spring clips 495b are joined together at their centers by a connecting bar, so that the spring clips 495b and their connecting bar form an "H" shape. When the proximal ends of the spring clips 495b are clamped together, the spring clips 495b can rotate relative to each other. The spring clips 495b are configured to engage with connector elements on an acid bag (or other acid supply source, not shown), so that the spike member 495a can be engaged with the bag until the user removes the clip 495b. For example, the distal ends of the clips 495b can include barbs that engage with the acid supply source, and by clamping the proximal ends of the clips 495b together and separating the barb elements from the acid supply source at the distal ends of the clips 495b, the clips can be detached from the acid supply source. The acid bag spike 495 can also include a valve 495c (in this case, a pinch clamp) that opens / closes the line of the acid bag spike 495. According to one aspect of the present invention, the acid bag spike 495 can be replaced with another component such as an acid jag straw (not shown) or other structure (disconnected from the acid supply line 494 by the cap connector 496). When used with a jag straw, the cap connector 496 can engage with the opening of the acid jag so as to cover the opening of the acid jag like a cap. Alternatively, the jag straw can have a spiked end and be capable of penetrating a self-sealing (e.g., rubber) membrane that covers the opening of the acid jag. Thus, depending on the acid supply structure (jag, bottle, bag, etc.), various types of components can be attached to the acid supply line 494.

[0146] Figure 26 is a close-up view of the E-shaped fork connector 491 and the corresponding connection point 512 on the front panel 511. The E-shaped fork connector 491 has three parallel forks (corresponding to the bicarbonate line and acid supply lines 492, 494, and the water supply line 493) that engage with the corresponding receiving holes of the connection point 512. The E-shaped fork connector 491 and the receiving holes of the connection point 512 are configured such that the central lumen (water supply line 493) is disposed upward or otherwise outward from the common plane of the two outer lumens (bicarbonate and acid supply lines 492, 494). Thus, the E-shaped fork connector 491 cannot engage with the connection point 512 unless properly oriented, ensuring that the bicarbonate and acid supply lines 492, 494 are properly connected. The E-shaped fork connector 491 includes, for example, a pair of spring tabs 491a that can engage with the corresponding slots 512a of the connection point 512 when the forks are properly positioned in the receiving holes of the connection point 512. With the tabs 491a engaged with the slots 512a, the E-shaped fork connector 491 cannot be easily detached from the connection point 512, providing an auxiliary means for reducing the possibility of accidental separation. The E-shaped fork connector 491 can be severed by pushing the tabs 491a toward each other such that the barbs at the distal ends of the tabs 491a separate from the slots 512a. The connection point 512 has similar spring tabs 512b that can detach the connection point 512 from the front panel 511.

[0147] According to another aspect of the present invention, a disinfection connector (not shown) engages with the connection point 512 for use during the disinfection procedure. The disinfection connector has three parallel forks in the same orientation as the E-shaped fork connector 491, such that the forks can engage with the receiving holes of the connection point 512. The passages within the forks of the disinfection connector terminate in a common chamber within the disinfection connector. Thus, during the disinfection procedure, the bicarbonate flow line, the acid flow line, and the water flow line are all interconnected, and each flow line can be disinfected during the disinfection procedure (this is shown as a dotted reverse "T" line at 49 in FIG. 6).

[0148] According to another aspect of the present invention, the blood lines 203, 204 are provided with connectors capable of making two types of connections. The first type of connection is a plug-in or press-fit connection in which the connector is pushed into the receiving lumen, and is a leak-free connection made without the need for rotation of the connector or the receiving lumen. The second type of connection is a screw-type connection in which the leak-free connection is made by a screwing engagement between the connector and the complementary element. For example, FIGS. 27 and 28 are a perspective view and a side view of a blood line connector 202 used with the blood lines 203, 204 and engageable with a blood line connection point 514 on the front panel 511. The connector 202 includes a tube connection end 202a for connecting to the corresponding blood lines 203, 204 and a patient access connection end 202b configured to connect to both the patient access and the connection point 514 to establish a leak-free connection. At the patient access connection end 202b, the connector 202 includes a frustoconical member 202c having a female thread portion configured to engage with a male thread patient access. For example, the frustoconical member 202c may be part of a male Luer connector including a central tube 202 extending from the center of the frustoconical member 202c. When making a Luer connection, the tube 202e extends into the female Luer connector at the patient access, and the screwing portion inside the frustoconical member 202c can engage with the threads of the female Luer connector of the patient access (artery or vein). Such a Luer connection is standard when connecting the blood line to the patient access. However, the connector 202 can be engaged with the connection point 514 simply by pushing the patient access connection end 202b into the receiving hole of the connection point 514. When making this connection, the outside of the frustoconical member 202c can engage with a suitable sheet or other surface or element within the connection point 514 (e.g., a valve sheet, an O-ring or others) to form a seal between the frustoconical member 202c and the connection point 514. Additionally, or alternatively, the central tube 202e can be used to engage with the connection point 514 to establish a proper seal.The locking arm 202d extending rearward from the frustum-shaped member 202c can engage with the hole 514a of the connection point 514 (for example, the barbed portion of the arm 202d can engage with the hole 514a), and can assist in holding the connector 202 in the receiving hole of the connection point 514. The connector 202 can release the arms 202d by pressing them against each other (for example, by pressing the finger recess at the distal end of the arm 202d), separating the barbs from the hole 514a, and pulling out the connector 202. It should be noted that the connection point 514 includes a spring tab 514b that can selectively engage with / disengage from the front panel 511. The connector 202 can be made by any suitable method such as plastic molding as a single integral part, for example.

[0149] FIG. 29 shows a perspective view of a blood circuit assembly 17 of another embodiment. This embodiment differs in several respects from that shown in FIGS. 18 and 19. For example, in this embodiment, the blood lines 203 and 204 have a cross-section similar in shape to the number "8", with one part of the "8" containing a lumen for transporting blood or other fluid and the other part of the "8" transporting a conductor. That is, the blood lines 203 and 204 have a lumen through which blood and other fluids can flow and another lumen through which a conductor can pass. Further details regarding this and other arrangements will be described later with reference to FIGS. 37-49. Similarly, as will be described in more detail later, a conductor can be used to detect a break in the blood lines 203, 204 from a patient or other connection point. Further, the braiding tray 171 of FIG. 29 differs from that shown in FIG. 19 in the following respect. That is, the engagement member 174 can have slots or holes for the blood lines 203, 204 to engage, but in this embodiment, the engagement member 174 need not engage the blood lines 203, 204 so as to resist tension below the lines 203, 204, for example, to carry the lines in a closure. Instead, in this embodiment, the blood lines 203, 204 can be moved freely with respect to the engagement member 174. Another change in the embodiment is that the engagement member 174 includes a push plate spanning both lines 203, 204. This is in contrast to the configuration of FIG. 19 in which each line 203, 204 is engaged by a separate engagement member 174. The configuration of FIG. 29 can provide advantages in several embodiments in which a user can engage the lines 203, 204 with respect to a slot 517 leading to a closure in a single operation (see FIG. 22). In one embodiment, the slots 517 can each be associated with an air detector that operates to detect whether there are air bubbles in the line 203 or 204 (e.g., by an optical detection method or other detection method such that air in the line 203 or 204 can be detected by one of the respective air detectors of the slot 517).Therefore, in addition to or as an alternative to the closing part or other mechanisms that position lines 203 and 204 in a desired manner, the engaging member 174 can function to associate the lines with an air detector or other functions. In this embodiment, the engaging mechanism 174 includes slots disposed on the lower side of the push plate that engage the narrower portions of lines 203 and 204 (e.g., the portions that carry the conductors) to position the conductors near the push plate. This can help position lines 203 and 204 within slot 517 so as not to interfere with an air detector that operates such that the conductors detect air in lines 203 and 204. As described above, the slots in the push plate that engage lines 203 and 204 can engage the lines such that the lines can advance relative to the push plate along their lengths but not rotate relative to the push plate. FIG. 30 shows a close-up view of a portion of the blood circuit assembly of FIG. 29 and shows an arrangement for at least partially conforming a portion of the braiding tray 171 to the shape of the blood lines 203 and 204 held by the tray 171. Similar to the engaging member 174, the portion of the tray 171 that engages lines 203 and 204 can be configured to orient lines 203 and 204 such that the conductor portions of the lines face outward. This can help properly position lines 203 and 204 relative to the engaging member 174 or other parts of the assembly 17.

[0150] It should be understood that any and all aspects of the inventions described herein can be combined with or otherwise integrated with any of the other aspects of the described inventions and / or embodiments. For example, a dialysis system incorporating one or more aspects of the inventions described herein can have a line cutting function such as that described in connection with FIGS. 37-49. Such cutting functions can include 1) an electrical circuit or other suitable circuit that detects a change in voltage, resistance, or other characteristic indicative of the cutting of blood lines 203, 204 with respect to associated connectors, 2) the positioning of detection electrodes appropriately proximate to a patient or other reference, 3) one or more connector arrangements, 4) a blood line piping configuration or other suitable configuration in which the blood line supports both a fluid flow lumen and an electrically conductive function, and the like. For example, in one aspect of the invention, a blood circuit assembly can comprise electrical circuit components suitable for use in detecting the cutting / connection of one or more of the blood lines of a blood line, one or more blood pumps, an air trap, and a braiding tray. Such a configuration allows a user to make several different connections, whether fluid, pneumatic, and / or electrical, in a relatively uncomplicated and simple manner.

[0151] Accordingly, aspects of the present invention generally relate to systems and methods for detecting the severance of an indwelling vascular line or its attachment tubing used in dialysis treatment, such as a catheter or needle. If severance is not detected promptly, particularly if the blood within the catheter or tubing is under positive pressure, rapid blood loss can occur. Examples of environments with positive intravascular pressure include the positive pressure associated with an artery or arteriovenous fistula, or the positive pressure associated with an extracorporeal blood pump circuit. In hemodialysis, for example, a blood pump can generate a blood flow rate of 400 ml / min to 500 ml / min, making rapid and reliable severance detection particularly desirable. Indeed, any medical treatment involving a relatively high flow or high pressure extracorporeal circulation (such as hemoperfusion or cardiopulmonary bypass, etc.) can be made safer by having an effective system for monitoring the integrity of the artery (draw) and vein (return).

[0152] In hemodialysis, for example, extracorporeal blood circulation can be achieved by a vascular access using either a single indwelling catheter or two separate indwelling catheters. In a single catheter system, blood is alternately withdrawn from and returned to the body through the same cannula. Disconnection in this system can be quickly detected by placing an air monitor in or near the pump inlet, because air will be drawn into the line from the disconnection site during the blood withdrawal phase of pumping. On the other hand, in a two catheter system, blood is typically continuously withdrawn from the body through one catheter inserted into a blood vessel or fistula and returned to the body through a second catheter inserted at some distance from the first catheter in the same blood vessel or in a completely separate blood vessel. In a two catheter system, a sensor can also be used to monitor whether the catheter or tubing is disconnected in the blood withdrawal or "arterial" segment by detecting the presence of air trapped in the arterial tubing when blood is withdrawn from the blood vessel under negative pump pressure and / or positive fistula pressure. However, air detection in the line cannot reliably detect disconnection in the venous (return) segment of the extracorporeal circuit. In this case, if the blood withdrawal path remains intact, air will not be introduced into the line. Therefore, it is particularly important to be able to detect a break in the continuity of the return line from the extracorporeal pump to the vascular access site.

[0153] In one aspect, the present invention includes a system for detecting whether a vascular access device, such as a needle, cannula, catheter, etc., has been severed or detached from a blood vessel or vascular graft. The system includes a fluid delivery device that provides for the flow of fluid into a blood vessel through a tube or conduit through an indwelling needle or catheter at a first site of the blood vessel or graft. The fluid can be an electrolyte solution or other solution suitable for intravenous infusion, or it can be blood or blood components. Electrodes are arranged to contact or be in fluid communication with the lumen of the conduit, and a second electrode is arranged to be in fluid communication with the blood within the blood vessel or graft through a second site of the blood vessel or graft. An electronic circuit is connected to the first and second electrodes and is configured to send control signals to the first and second electrodes to measure the electrical resistance of the fluid between the first electrode and the second electrode, where at least one of the electrodes is arranged closer to the blood vessel or graft than the fluid delivery device. In some embodiments, the electrodes are arranged at about 50% to 70% of the distance from the fluid delivery device to the blood vessel or graft. In other embodiments, the electrodes are arranged at about 70% to 90% or more of the distance from the fluid delivery device to the blood vessel or graft. The fluid delivery device can comprise a pump for blood or other therapeutic or diagnostic fluids. The fluid delivery device can be part of a hemodialysis blood flow circuit that may or may not include a blood pump, a dialyzer cartridge, or an air trap and associated piping. The second electrode can be arranged in contact with the lumen of a second conduit or tube that is in fluid communication with the blood vessel or graft at a second site. The second conduit can form part of the fluid flow path from the blood vessel or graft to the fluid delivery device. The fluid within the second conduit can be blood that is being delivered to an extracorporeal blood flow circuit.

[0154] The system can comprise first and second connectors that connect a pair of vascular access catheters accessing vascular segments or vascular graft segments at two different sites. The first and second connectors can each be connected to a flexible tube leading to a fluid delivery device. Each connector can comprise an electrode exposed in the lumen of the connector. A wire can be attached to each connector, and the wire can be connectable to an electronic circuit at its other end. The flexible tube can be a double-lumen tube having a first lumen for conveying fluid and a second lumen for conveying the wire. The wire of each tube can be connected to a connector for connection to an electronic circuit at the other end of the tube.

[0155] An electronic circuit or associated microprocessor can be configured to convert the voltage measured by the electronic circuit across both ends of a terminal connected to the electrode into a resistance value. The system can comprise a controller configured to receive a signal from the electronic circuit or microprocessor, the signal representing the electrical resistance between the electrodes, and the controller is programmed to trigger an alarm signal when the electrical resistance value exceeds a predetermined threshold. The alarm signal can be an audible or visual signal for the person whose blood vessel is being accessed, and optionally, the alarm signal can include an electrical command for a tubing closure device. The tubing closure device can be actuated to mechanically close one or more of the tubes leading from the vascular access site. The tubing closure can operate in a plurality of ways, such as electromechanically, hydraulically or pneumatically, for example.

[0156] In another aspect, the present invention includes an apparatus for monitoring the continuity between a vascular access device having first and second vascular connectors and a blood vessel or vascular graft segment, wherein the first connector is attached at its proximal end to the distal end of the fluid conveyance lumen of a first double lumen tube, and the second connector is attached at its proximal end to the distal end of the fluid conveyance lumen of a second double lumen tube. The first connector includes a first electrode that contacts the lumen of the first connector and is electrically connected to a wire within the wire conveyance lumen of the first double lumen tube, and the second connector includes a second electrode that contacts the lumen of the second connector and is electrically connected to a wire within the wire conveyance lumen of the second double lumen tube. The wire within the first double lumen tube and the wire within the second double lumen tube are each connected to an electrical connector at the proximal end of the double lumen tube. The distal end of each connector can be configured to have a locking function that provides a reversible airtight connection between the connector and a mating connector of a blood vessel catheter. The proximal end of the double lumen tube can be connected to an arterial side blood pump and a venous side air trap, and in a hemodialysis system, the blood pump and the air trap can each be reversibly connectable to a dialyzer cartridge.

[0157] In another aspect, the present invention includes a vascular connector, the vascular connector comprising a proximal fluid connection end, a distal fluid connection end, and an electrode configured to electrically connect the fluid conveyance lumen of the connector to a wire external to the vascular connector. The proximal end of the connector can be configured to connect to a flexible tube, and the distal end of the connector can be configured to connect to a mating connector of a blood vessel catheter. The electrode can be installed in a conduit of the connector that connects the lumen of the connector to the exterior of the connector. The electrode can be housed within the conduit to provide an airtight seal between the lumen and the outside of the connector. An elastomeric member, such as an O-ring, can be installed between the electrode and the conduit to contribute to the airtight seal.

[0158] In another aspect, the present invention is an electrical circuit for measuring the resistance of a liquid between a first electrode and a second electrode, wherein the first electrode is connected to a first terminal of the electrical circuit, the second electrode is connected to a second terminal of the electrical circuit, a capacitor C1 connected to the first terminal at a first end, a capacitor C2 connected to the second terminal at a first end, a known reference resistance Rref connected to a second end of the capacitor C1 at a first end, and (a) connecting a first reference voltage V+ to the second end of Rref and connecting a lower second reference voltage V- to the second end of C2 to form a first switch configuration, or (b) connecting a first reference voltage V+ to the second end of C2 and connecting a lower second reference voltage V- to the second end of Rref to form a second switch configuration, switching means, and measuring means for measuring a voltage Vsense at a connection between C1 and Rref, whereby the electrical circuit is configured to determine a value of the resistance of the liquid based on the known reference voltage Rref and the observed voltage Vsense for each of the first and second switch configurations. The resistance Rref can be selected to be a value that enables measurement of the conductivity of an electrolyte solution or another solution suitable for intravenous injection. The electrolyte solution can include a dialysis solution. The resistance Rref can also be selected to enable measurement of the resistance of a certain volume of blood between the first electrode and the second electrode. Conductivity circuit Using the exemplary electrical circuit shown in FIG. 37, the conductivity or resistance of a target fluid can be measured. In one embodiment, the fluid can be an electrolyte solution or a dialysis fluid, and the circuit can ultimately provide a measurement of the fluid's conductivity to ensure its compatibility for intravascular administration. In addition to monitoring the concentration of dissolved solutes in the fluid, the electrical circuit can also monitor whether there is a possibility of interruption in the continuity of the fluid between electrodes connected to the circuit. For example, it can be used to monitor an intravenous fluid line for the presence of air bubbles or contaminants. In another embodiment, the fluid can be blood, and using the measured change in electrical resistance of a blood flow path (e.g., within a conduit), it can indicate whether a discontinuity occurs between the blood flow path and the measurement electrodes. For example, the blood flow path may include a column of blood between two electrodes including an indwelling needle or catheter in the body in a segment of a blood vessel, arteriovenous fistula, or graft. Disruption of vascular access can introduce air into the blood flow path, potentially changing the resistance of the blood column between the electrodes. The electrical circuit can be easily modified (depending on its use) to adjust for the difference between the impedance of the blood flow path and the impedance of the dialysis fluid.

[0159] Using the circuit shown in FIG. 37, an unknown resistance Rx of the target medium 1 can be measured using low-cost electronic components, especially when the unknown resistance includes a conductive path through an electrolytic fluid. A switching network 2 with a pair of multiplexers enables connection of the reference voltages V+ and V− to the node VA. The target medium 1 having the unknown resistance Rx is connected to the terminals VTA and VTB 3 to form a voltage divider with the reference resistor Rref 4. To perform conductivity measurement, an alternating voltage can be provided to the target medium 1 through the switching network 2 to a voltage divider generated by the known reference resistor Rref 4 (e.g., 680 ohms in the case of a dialysis fluid) and the unknown resistance Rx of the target medium 1. The midpoint of the voltage divider is measured. The signal Vsense at point 8 is buffered by an amplifier 10 to generate the input signal Vin of an analog-to-digital converter (ADC) 111. When the voltage divider is driven first in one direction and then in the other direction, Vsense switches between two values. This signal is valid only for a short period after the switch, which is because the fluid in the conductivity cell 1 is AC-coupled to the circuit through the capacitors C1 and C2 6. Thus, the DC-blocking capacitors C1 and C2 6 can be used to prevent DC current from passing through the unknown resistance (which may include a conductive path through an electrolytic fluid or blood). In one embodiment, the series capacitor C can include two capacitors in parallel, one having a value of, for example, 0.1 μF and the other having a value of, for example, 10 μF. A series resistor 7 can be used to reduce exposure to noise and surge voltages by the switch network and other sensing circuits. The ADC 111 can acquire multiple samples of the signal when the circuit switches between two configurations.

[0160] The switching network 2 can be driven by a pair of alternating two-valued control signals 131, 144 that connect VA to V+ and VB to V- during one half-cycle and connect VB to V+ and VA to V- during the other half-cycle. As a result, the waveform at the Vsense node 58 will be similar to the waveform 20 shown in FIG. 38. In this embodiment, Vref is 4 volts, and as shown in FIG. 38, the Vsense amplitude is less than 4 volts. The voltage divider 8 provides voltages V+ and V- that are close to the positive reference voltage Vref and close to ground, respectively. In one embodiment, R1 can have a value of 10 ohms and R2 can have a value of 2K ohms. When both multiplexers of the switching network 2 are instructed to zero, the circuit is stopped, and the lower voltage is applied to the terminals VTA and VTB 3. When VA is high and VB is low, the higher voltage is applied to the reference resistor Rref 4, and the lower voltage is applied to the target medium 1 having the unknown resistor Rx. When VB is high and VA is low, the higher voltage is applied to the target medium 1 having the unknown resistor Rx, and the lower voltage is applied to the reference resistor Rref 4.

[0161] The voltage change ΔVsense before and after each rectangular wave edge can be shown to be determined only by the reference resistor Rref 4, the unknown resistor Rx of the target medium 1, and any series resistance (including, for example, Rs 7), and is generally independent of the series capacitors C1 or C2 6 because during this short period, the capacitors act as incremental short circuits. In particular, Δα = ΔVsense / (V+ - V-) = (Ry - Rref - Rth) / (Ry + Rref + Rth) = (ρ - 1) / (ρ + 1), where Ry = Rx + 2Rs + Rth, Rth is the source series resistance from multiplexer 2 and voltage divider 8, and ρ = Ry / (Rref + Rth) (the source series resistance Rth can be derived as the sum of the resistance of multiplexer 2 and the Thevenin equivalent resistance of voltage divider 8. For example, when R1 = 10 ohms and R2 = 2K ohms, Rth = R1∥(R1 + R2) = 9.95 ohms). Thus, when Ry is a short circuit, ρ = 0 and Δα = -1. Then, the change in voltage ΔVsense at the sense node is equal to the change in voltage at VB with an amplitude opposite to that at the drive node VA. When Ry is an open circuit, ρ = ∞ and Δα = 1. Then, the change in voltage ΔVsense at the sense node is equal to the change in voltage at the drive node VA. Therefore, if this change in voltage is measured, the previous equation can be solved for the unknown resistance Rx.

[0162] Rx = ρ(Rref + Rth) - 2Rs - Rth, where ρ = (1 + Δα) / (1 - Δα) As shown in FIG. 37, to remove high-frequency noise, a low-pass filter 9 can be formed by resistor Rf and capacitor Cf. In one exemplary configuration, Rf can have a value of 1K ohms and Cf can have a value of 0.001 μF. Then, buffer amplifier 10 and analog-to-digital converter (ADC) 111 can measure the sensed voltage for a computer or digital signal processor (not shown).

[0163] The reference voltages V+ and V- can advantageously be derived from the voltage divider 8 such that V+ is close to the reference voltage Vref of the ADC111 and V- is close to the ground reference voltage of the ADC111. For example, when R1 = 10 ohms, R2 = 2 k ohms and Vref = 4.0 V, V+ = 3.980 V and V- = 0.020 V. Thereby, both voltages are within the active sensing region of the ADC111 but close to its edges, and they can be used for calibration (described later). The switch SW1 12 can be used to assist in the calibration of the load resistance sensing.

[0164] With some improvements, the errors associated with the variations in component values can be reduced. First, a calibration step can be introduced where VA is switched to V+ for a relatively long period until it stabilizes and becomes approximately equal to V+ (at which point the ADC111 can measure Vsense). The second calibration step can include switching VA to V- for a relatively long time until Vsense stabilizes and becomes approximately equal to V- (at which point the ADC111 can perform another measurement of Vsense). Thereby, the ADC111 can measure both V+ and V-.

[0165] Second, as shown in FIG. 38, during the switching of the rectangular wave, a dimensionless number Δα can be calculated as follows using the ADC111 readings before and after both edges of the switching waveform. Δα = ΔVsense / (V+ - V-) = [(V2 - V1) + (V3 - V4)] / 2(V+ - V-) As a result, ΔVsense = [(V2 - V1) + (V3 - V4)] / 2 can be measured using both edges of the waveform, whereby the asymmetric response to the circuit may be canceled out. Alternatively, the average voltage at approximately the midpoint of the waveform can be used, whereby, for example, Δα = ΔVsense / (V+ - V-) = [(V7 - V6) + (V7 - V8)] / 2(V+ - V-) and ΔVsense = [(V7 - V6) + (V7 - V8)] / 2. Further, only the differential measurement value of the input signal Vin of the ADC111 can be used. Thus, any offset error of the buffer amplifier 10 and the ADC111 can be canceled out. Also, Δα is a metric quantity based on measurements using the same signal path. Thus, any gain error of the ADC111 can be canceled out.

[0166] The reference resistor Rref 4 can be arbitrarily selected to be equal to the geometric mean of the endpoints of the unknown resistance in the desired range, taking into account the series resistance Rs 7. For example, when Rs = 100 ohms and Rx varies from 100 ohms to 3000 ohms, Ry = Rx + 2R varies from 300 ohms to 3200 ohms, and Rref should be approximately the square root of (300 ohms × 3200 ohms) = 980 ohms. To measure an unknown resistance in the range of 100 kΩ to 300 kΩ (such as in a column of blood extending from one electrode to another through an arteriovenous shunt), the reference resistor Rref 4 can be changed to approximately 200 kΩ, and the filter capacitor Rf of the low-pass filter 9 at the input to the buffer amplifier 10 can be completely removed.

[0167] Since the output of the voltage divider is a non-linear function of its resistance ratio, an error or noise in the reading from the ADC111 results in their lowest partial errors (sensitivity) in the calculation of Ry when Ry is equal to Rref, and the greater the sensitivity, the more Ry diverges from the reference resistance Rref. Specifically, it can be shown that the sensitivity in the resistance ratio is as follows.

[0168] Sρ=(1 / ρ)·∂ρ / ∂Δα=2 / [(1+Δα)(1-Δα)]=2 / [1-(Δα 2 When Ry = Rref, ρ = 1, Δα = 0 and Sρ = 2. Thus, for a change in Δα of 0.001 (0.1% of the ADC full scale) around this point, the calculated resistance Ry changes by 0.002, i.e., 0.2%. As shown in Table 1, the sensitivity increases as ρ diverges from 1.

[0169]

Table 1

[0170] Figure 39 shows that the noise / error sensitivity doubles at an unknown / reference resistance ratio of about 6:1 and triples at a ratio of 10:1. Resistance measurements outside this range may be affected by an increased sensitivity to noise and errors.

[0171] For calibration purposes, the resistance measurement can be made using switch SW1 12 to calibrate out the point where Rx = 0. Preferably, this switch 12 should be placed across or as close as possible to terminals VTA and VTB 3, thereby providing a true zero - point calibration. However, in practice, placing switch 12 close to terminals VTA and VTB 3 may make switch 12 susceptible to external noise and surge voltages, and there is a possibility of introducing a DC leakage current into the target medium 1.

[0172] ​The series capacitances C1 and C2 6 and the use of a rectangular wave are important for an unknown resistor that includes an electrolyte conduction path. There are at least two reasons for this. First, in many applications, it may be important to prevent direct current from flowing through an electrolytic solution or a body fluid having similar characteristics, otherwise, electroplating and / or electrolysis of the electrodes at terminals VTA and VTB 3 may occur. In this circuit, capacitors C1 and C2 6 block direct current. Further, since the capacitors can pass a very small current (below microamperes), using an alternating rectangular wave voltage can help further limit the average current.

[0173] Second, if a small electrochemical direct current voltage is induced in the target medium 1 (for example, the electrodes in the fluid path may oxidize at different rates over time), this direct current voltage can be blocked by capacitors C1 and C2 6. Since the method of calculating the resistance performs a differential measurement, any residual direct current voltage can be canceled out during the process of calculating the unknown resistance Rx of the target medium 1.

[0174] Vascular Disconnection Detector By appropriately modifying a conductivity measurement circuit such as the one described above, it is possible to detect the conductivity of blood and changes in conductivity. More specifically, it is possible to detect changes that occur when air enters a volume of blood in terms of its conductivity. This situation may occur, for example, when an intravascular access site becomes disconnected within an extracorporeal blood circuit.

[0175] Using the circuit shown in FIG. 37, the resistance of a volume of fluid in the conductivity cell or line 1 can be measured. When measuring Rx of the conductivity cell 1 representing the resistance or conductivity of a volume of dialysis solution, a convenient value for the reference resistor Rref 4 can be selected to be approximately 680 ohms. When measuring Rx of line 1 representing the resistance or conductivity of a column of blood extending from the first cannula or needle through the arteriovenous shunt to the second cannula or needle, a convenient value for the reference resistor Rref 4 can be selected to be approximately 200 k ohms.

[0176] The advantages of using this circuit to monitor the continuity of a column of body fluid such as blood or plasma include the following. That is, capacitive coupling to the conductivity cell or line 1 blocks direct current that could cause plating and corrosion of the electrodes at terminals VTA and VTB, and for patient safety, the voltage and current levels are very low and isolated, and current flows only briefly while the measurement is being made. No current flows between measurements.

[0177] Using the lower value (e.g., 680 ohms) of the reference resistor Rref 4, this circuit is appropriately configured for dialysis fluid conductivity measurement. Using a much higher value (e.g., 200 k ohms) of the reference resistor Rref 4, this circuit is appropriately configured to measure the resistance between the arterial and venous needles to detect disconnection of the vascular needle from the arteriovenous shunt.

[0178] Electrode arrangement The continuity of the fluid column leading from the fluid delivery device to the patient's blood vessel or vascular graft can be monitored using the electronic circuit described above. The fluid being delivered can include blood or any electrolyte solution including a dialysis fluid. The following discussion includes hemodialysis systems, but the same principles of operation of the present invention can be applied to any device configured to deliver fluid to a patient through a vascular access. In the embodiment shown in FIG. 40, the conductivity of a volume of blood or other fluid within the fluid flow circuit 100 of a hemodialysis machine 200 can be electronically monitored using electrodes at each end of that volume that are in direct contact with the blood or other fluid. Using an electrical circuit such as that shown in FIG. 37, one electrode can be connected to the VTA terminal of the circuit and the other electrode can be connected to the VTB terminal of the circuit. The voltage applied to the electrodes by the circuit can be a sufficiently small (e.g., about 4 volts or less), sufficiently short-duration, and sufficiently isolated DC voltage so as to prevent any damage to the patient. In this example, a fluid flow circuit 100 is shown that includes the intraluminal volume of a portion of the patient's blood vessel or shunt 134 located between the arterial access needle 102, arterial catheter tubing 104, arterial catheter tubing connector 106, arterial blood circuit tubing 108, transition section 110 between the vascular circuit tubing 108 and the hemodialysis machine 200, blood pump inlet line 112, blood pump 13, blood pump outlet line 116, dialyzer 14, dialyzer outlet line 120, air trap 122, transition section 124 between the hemodialysis machine 200 and the venous blood circuit tubing 126, venous catheter tubing connector 128, venous catheter tubing 130, venous access needle 132, and the arterial access needle 102 and the venous access needle 132. The invention described herein also encompasses situations where the arterial access needle may be present within one of the patient's blood vessels and the venous access needle may be present in a separate blood vessel somewhat removed from the arterial access site. Further, using the circuit described above, the integrity of the vascular access within a fluid delivery system that does not have a venous return line as shown in FIG. 40 can be monitored.In that case, for example, the electrode at location B can be paired with an electrode in contact with the fluid of a dead-end line that communicates with a second needle or cannula accessing the blood vessel or vascular graft. In another example, an implantable hollow cannula or solid trocar in a blood vessel segment can be equipped with a conductive wire, which can thereby serve as a second electrode in the monitoring system. The accessed blood vessel segment may be an arteriovenous fistula formed surgically and may include an artificial conduit such as a GoreTex (registered trademark) vascular graft. The term "arterial" is used herein to refer to the portion of the blood flow circuit that conducts blood away from the patient and towards the hemodialysis machine 200. The term "venous" is used herein to refer to the portion of the blood flow circuit that conducts blood away from the hemodialysis machine 200 and back towards the patient. The term "access needle" is used herein to refer to a needle or catheter device that penetrates a patient's blood vessel segment or fistula. In various embodiments, it can be permanently fused or reversibly connected to the corresponding catheter tubing 104, 130.

[0179] The continuity of any segment of the fluid flow circuit 100 can be monitored by positioning two electrodes in contact with the fluid on both sides of the fluid and blood-containing segment. To monitor for breaks in the arterial access needle 102 or arterial catheter tubing 104 or venous access needle 132 or venous catheter tubing 130, one electrode can be placed in continuous communication with the lumen on the venous side of the blood flow circuit, and the second electrode is placed in continuous communication with the lumen on the arterial side of the blood flow circuit. In one embodiment, the two electrodes can be placed at or near the dialysis machine 200, with one electrode contacting the blood upstream of the blood pump 110 and the second electrode contacting the blood downstream of the dialyzer 14 and / or air trap 122. For example, the electrodes can be incorporated at transition locations 110 and 124.

[0180] In another embodiment, one of the electrodes can be positioned to contact the fluid of the fluid flow circuit 100 at a point closer to the vascular access site 134 than a device (e.g., a dialysis machine) used to deliver the fluid flow to the accessed blood vessel or vascular graft. In a preferred embodiment, both electrodes can be positioned closer to the patient's blood vessel or vascular graft than the devices associated with the dialysis machine 200. Thereby, electrical interference associated with the dialysis machine 200 can be further reduced. Electrode A can be conveniently disposed at or near the arterial catheter tubing connector 106, and the second electrode B can be conveniently disposed at or near the venous catheter tubing connector 128. In this configuration, the electrical conduction path from the first electrode through the patient's vascular access to the second electrode is much shorter than the path that extends back towards the dialysis machine 200, i.e., the electrical resistance is low. In one embodiment, the access catheters 104 and 130 can be shortened to about 1 foot, and the arterial tubing 108 and the venous tubing 126 can be about 6 feet long. Due to the conductive properties of the fluid within the circuit, the electrical resistance associated with the paths incorporating the tubing 108 and 126 and the components of the dialysis machine 200 can be made many times greater than the electrical resistance associated with the path through the patient's blood vessel or shunt 134.

[0181] Therefore, the electrical interference related to the dialysis machine 200 is reduced, and the change in electrical resistance due to the disconnection related to access can be detected more easily. Preferably, the electrodes A and B are positioned to exceed 50% of the distance from the dialysis machine to the patient. More preferably, the electrodes A and B are arranged near the last separable fluid connection before reaching the patient. In one embodiment of the hemodialysis system, the blood pipes 108 and 126 are approximately 6 feet in length, and the arterial catheter pipes 104 and the venous catheter pipes 130 are 2 feet or less in length. Then, a convenient position for the electrodes A and B is at the arterial line connectors 106 and the venous line connectors 128 (which can be, for example, Luer-type connectors or variations thereof) that connect the arterial blood circuit tubes 108 and the venous blood circuit tubes 126 to the arterial catheter tubes 104 and the venous catheter tubes 130. Connector electrodes As shown in FIGS. 41A and 41B, in one embodiment, a blood line connector for the blood circuit of a hemodialysis system can incorporate an electrode that can contact the liquid within the lumen of the connector. In one aspect, the electrode can comprise an annular conductive cap 310 disposed at the tube connection or proximal end 302 of any suitable connector, such as connector 300. The electrode is preferably composed of a durable and corrosion-resistant material, such as stainless steel. The distal connection end 304 of the connector 300 can be configured to sealingly engage a corresponding Luer-type connector of an arterial or venous catheter, for example. The inner annular surface 312 of the cap 310 can contact (partially or entirely) the liquid present within the lumen 314 of the connector. As shown in FIG. 41B, an O-ring 316 or a suitable sealant can be disposed between the cap electrode 310 and the proximal end 302 of the connector to maintain a fluid-tight connection between the connector and any flexible tube attached to the connector.

[0182] In a hemodialysis system, or other extracorporeal system where a blood-bearing component is sterilized or disinfected using a heated fluid, an elastomeric O-ring can be particularly useful. The coefficient of thermal expansion of the plastic components of the connector can be significantly different from that of the incorporated metal electrodes, and thus a permanent seal may not be maintained after one or more sterilization or disinfection procedures. By adding an elastomeric component such as an O-ring at the junction between the electrode and the connector seat in which the electrode is disposed, a seal can be maintained by accommodating the different expansion and contraction rates between the electrode and the connector.

[0183] As shown in FIG. 42, in one embodiment, a conductive electrode 310 (e.g., composed of stainless steel) can be incorporated into a portion of the connector 300 (at its proximal end 302 or or at its distal connection end 304), and an end of the flexible tube 318 can be disposed over that portion of the connector 300. In this embodiment, the electrode 310 is generally cylindrical and has a tapered portion 320 at the proximal end to facilitate a slip fit mounting of the end of the segment of the flexible tube 318 onto the outer surface of the electrode 310. As shown in FIG. 42, the inner surface of the electrode 310 has an internal shelf-like protrusion 322 such that the electrode cap 310 can slide over and abut the proximal end 302 of the connector 300. The connector 300 can be composed of any suitable rigid material including metal or more typically a plastic material. The shelf-like protrusion 322 serves to ensure that the smaller diameter inner surface 312 of the electrode 310 is properly positioned to contact the liquid (e.g., blood) passing through the lumen 314 of the connector 300. The connection between the connector 300 and the electrode 310 and the connection between the electrode 310 and the terminal end of the flexible tube 318 that overlays it can be made airtight or permanent using any suitable adhesive that is compatible with the composition of the components.

[0184] To ensure a more secure seal to prevent leakage of blood between the connector and the electrode, and to limit the area under the electrode where blood components may migrate and remain, an O-ring 316 can be incorporated near the internal shelf-like protrusion 320 on the inner surface of the electrode 310. This is shown in enlarged detail in FIG. 42. In this example, the O-ring 316 seals between the stainless steel electrode 310 and the distal end 302 of the connector 300. To hold the extended end of the flexible tube 318 over the proximal end 302 of the connector 300, a piercing element 324 of the proximal end 302 of the connector 300 can be incorporated into the connector design. In one embodiment, the electrode 310 is held in place by a portion of a flexible tube that extends over both the electrode 310 and the piercing 324 of the connector 300.

[0185] A wire 326 can be soldered, welded, or otherwise fixed to the outer surface of the electrode 310 and can proceed under the overlapping extended tubing 318 until it exits further distally along the connector 300. Thus, the wire can convey electrical signals to and from the electrode 310 when the inner surface 312 contacts the fluid within the lumen (e.g., blood). In the illustrated example, the wire 326 is soldered to the distal portion of the electrode 310, moves under the tubing 318, and appears at the abutment of the tubing 318 with the corresponding stopper 326 of the connector 300.

[0186] In another embodiment as shown in FIGS. 43A - 43C, a connector 400 as described in U.S. Patent Application Publication No. 2010 / 0056975 (the content of which is incorporated herein by reference) is modified such that the central portion 406 of the connector 400 can incorporate electrodes. By arranging the electrodes along the central portion 406 of the connector 400, there is no need to modify the distal connection end 404 of the connector, and there is no change in any interaction between the end portion of the flexible tube and the proximal end 402 of the connector. In this example, the blood line connector 400 is configured to make two different types of sealed connections at its distal connection end 404, including a female threaded connection portion 405 for a luer - type connector of a patient access line and an external press - fit connection portion 407 to a dialysis machine port for priming and recirculation of a disinfection fluid through a blood - carrying component of the dialysis system. The press - fit mechanism 407 is formed with a frustoconical shape on the outer surface of the distal end 404 of the connector 400, and the luer - compatible threaded mechanism 405 is formed on the corresponding inner surface of the distal end 404 of the connector 400. The outer surface of the frustoconical member is configured to make a sealed engagement with a seating portion of a mating connector of the dialysis machine 200 or other device. A pair of locking arms 408 extending proximally from the distal connection end 404 of the connector 400 can each have a barbed portion 409 that engages a corresponding locking mechanism of the mating connector of the dialysis machine and a finger recess 410 that aids in removing the barbed portion 409 from the dialysis machine. The barbed portion 409 serves to lock a frustoconical member that makes a sealed engagement with its mating connector of the dialysis machine when making a press - fit connection. The distal ends of the locking arms can be configured to attach to the connector through a flange 411 located proximal to the frustoconical portion 407 of the connector 400. The connector 400 has a proximal pipe - mounting end 402 that makes a sealed engagement with a flexible tube. The pipe - mounting end 402 can have one or more piercing mechanisms 412 that serve to prevent the end of the flexible tube from detaching from the connector 400.

[0187] FIG. 43B shows a side view of the connector 400, enabling the viewing of an access mechanism or port 420 that can allow for the placement of electrodes in direct communication with the lumen of the connector 400. In other embodiments, the access mechanism can accommodate an elastomeric stopper (with or without a diaphragm) to allow for sampling of fluid from within the lumen 414 of the connector 400 using a syringe with a sharp or blunt needle. Alternatively, the mechanism can serve as a port enabling connection of another fluid line to the lumen 414 of the connector 400.

[0188] In yet another embodiment, as shown in the cross-sectional view of FIG. 43C, the intermediate portion 406 of the connector 400 can have two access ports. The fluid access port 420a can serve as a sampling port, and the electrode port 420b can serve as an electrode cradle. The elastomeric stopper 422 within the sampling port 420a can be shaped to extend up to the lumen 414 of the connector 400, allowing for sampling of the fluid within the lumen 414 by a needle while maintaining an airtight seal. Alternatively, a luer-type connector with a capped or sealed diaphragm can be incorporated into the port, and the port can be connected to a syringe or catheter having a mating luer-type connector. The electrode port 420b can serve as a seat or cradle for the electrode 424. It can be press-fitted or cemented in place, sealed using an adhesive, or using an O-ring 416 as shown. The wire 426 can be soldered, welded, or otherwise fixed to the outer surface of the electrode 424, and the wire 426 can proceed in the proximal direction towards the dialysis machine 200 by the arterial tubing 108 or venous tubing 126 to which the connector 400 is attached.

[0189] In any of the above electrode embodiments, for the additional purpose of measuring the temperature of the fluid passing through the connector 300, 400 or a variation thereof, the electrode can be replaced with a properly sized thermistor, or a combination of a thermistor and a conductor. Wire assembly In one embodiment, wires that carry electrical signals to or from a pair of electrodes (one on the arterial side and one on the venous side of the blood flow circuit) of connectors 106, 128 can separately proceed away from blood conduits 108, 126 and back towards dialyzer 200, where they ultimately terminate and connect to a conductivity detection circuit, such as the conductivity circuit shown in FIG. 37. The conductivity circuit then provides a signal appropriately configured to the processor of the dialyzer to determine whether a change in fluid conductivity consistent with an access disruption has occurred. If a change in fluid conductivity has occurred, the processor can trigger an alarm state or initiate the stopping of blood pump 13, for example, triggering a mechanical closure of blood conduits 108 and / or 126.

[0190] Wires that extend together or separately between the dialysis machine and the patient are at risk of becoming entangled, breaking, or being cut. Thus, preferably, each wire 326 or 426 can be attached to, fused with, or otherwise incorporated into its associated tubing 108, 128. Incorporating the wire into its associated tubing provides a convenient way to protect the wire and the connection and to simplify the interface between the patient and the dialysis device. Exemplary ways to achieve this are shown in FIGS. 44A - 44D. In a preferred embodiment, the tubing is composed of a flexible material (such as silicone) that can be formed by an extrusion process. As shown in FIG. 44A, a coarse wire mesh can be embedded in the flexible silicone tubing as it is formed and extruded, similar to the fiber reinforcement of a flexible tube. As shown in FIG. 41A, in a manner similar to the construction of a fiber-reinforced tube, a wire mesh 500 can be embedded within the wall of the flexible tube 502 during extrusion. As shown in FIG. 44B, an insulated wire 504 can be joined to the outer surface of its adjacent tubing 506 during a secondary extrusion process or during a process where two structures are joined, for example, with an adhesive. As shown in FIG. 44C, a secondary extrusion can be performed to produce a secondary coaxial layer of tubing material 508 to capture a wire that extends along the outer surface of the tubing after a primary extrusion. As shown in FIG. 44D, the tubing 502 being formed can also be co-extruded with a wire 504 embedded in the wall of the tubing.

[0191] In some of the above methods, the resulting tube-wire combination may tend to twist because the coefficient of thermal expansion between the wire and the silicone material of the tubing is different. As the material cools after extrusion, the silicone may tightly capture the embedded wire, causing the cooled tube-wire bundle to twist. In a preferred embodiment, the wire lumen of the extrusion die is configured to be large enough to accommodate a cross-sectional area significantly larger than that of the wire to be embedded. Then, as the silicone cools, the passage surrounding the wire does not contract to the extent of tightly enclosing the wire. The coextrusion process incorporating the insulated wire can produce a tube-wire bundle as shown in FIG. 45. In this example, the flexible tube 502 is a coextruded product of the fluid conveyance lumen 601 and the wire conveyance lumen 602. Preferably, the wire 501 is a multi-strand wire for flexibility and durability and is coated or covered with a durable flexible synthetic insulating material 503 such as PTFE. The PTFE-based sheath 503 of the multi-strand wire 501 can withstand the high temperatures associated with the silicone tubing extrusion process, thereby maintaining its integrity along the portion 504 of the wire that ultimately exits the tubing for connection to either the dialysis machine 200 or the patient line connectors 106, 128. The coating or covering can also help prevent the wire from adhering to the sidewalls of the wire conveyance lumen during and after extrusion and during cooling.

[0192] FIG. 46 shows a cross-sectional view of an exemplary connector-wire-piping assembly. The proximal piping connection end of the connector 400 with the end of the double lumen piping 502 attached thereto is shown. The fluid conveyance lumen 601 is press-fitted and / or cemented to the proximal end of the connector 400, enabling fluid flow through the central lumen 414 of the connector 400. The finer wire 501 is soldered or otherwise attached to the electrode 424, and the electrode 424 makes conductive contact with the fluid present within the lumen 414 of the connector 400. The non-connected portion of the wire 501 passing outside the piping 502 is preferably coated with an insulating synthetic coating such as, for example, PTFE. Optionally, this portion of both the exposed wire and the coated wire can also be sealed with a sealing material such as RTV. The coated wire 503 enters the wire conveyance lumen 602 of the piping 502 near its terminal end to the connector 400. The wire / piping bundle then proceeds towards the dialysis machine 200, where, in the dialysis machine 200, the wire emerges from the piping to connect to a conductivity circuit such as that shown in FIG. 37.

[0193] FIG. 47 shows an exemplary extracorporeal circuit 210 that can be used as a detachable and replaceable unit in a hemodialysis device 220 as shown in FIG. 48. In this embodiment, the extracorporeal circuit includes a blood pump cassette 13, a dialyzer 14, a venous return air trap 122, an arterial blood tube 108, a venous blood tube 126, an arterial catheter connector 106, and a venous catheter connector 128. The arterial connector 106 and the venous connector 128 may be of the same type as the connector 300 shown in FIGS. 41A and 41B, or may be of the same type as the connector 400 shown in FIGS. 43A-43C, or may be a modification thereof. The arterial blood tube 108 and the venous blood tube 126 can be of the type shown in FIGS. 44A-44D or FIG. 45. Wires forming terminal connections to the electrodes of the connectors 106 and 128 exit the arterial tube 106 and the venous tube 126 as segments 504A and 504B and connect to the connectors, which ultimately pass that connection to terminals associated with a conductivity circuit such as that shown in FIG. 37 in the dialysis device. In the illustrated embodiment, the connector 526 is mounted on a support structure 214 for the blood pump 13 and the air trap 122.

[0194] FIG. 48 shows an exemplary hemodialysis device 220 configured to receive the extracorporeal circuit 210 shown in FIG. 47. In this example, the dialyzer 14 is already mounted on the device 220. The base portion 227 receives the control port of the mating blood pump cassette 13. A set of raceways or tracks 225 serves to braid pairs of arterial blood tube 106 and venous blood tube 126 when extended and not connected to the patient. Connector 224 receives the connection formed between wire segments 504A and 504B and connector 526 and passes it to the terminal connection portion of the conductivity circuit as shown in FIG. 1. The piping closure 226 is positioned to receive the venous blood tube 126 after exiting the air trap 122 and the arterial blood tube 108 after reaching the blood pump cassette 13. The closure 226 can be actuated pneumatically or electromechanically at any time, for example when an alarm condition requiring cessation of extracorporeal blood flow occurs. A set of arms of the closure 226 can be configured to rotate relative to the wall of the flexible tube to suppress or stop the fluid flow therein. Thus, the controller installed within the device 220 can receive signals from a conductivity circuit similar to that of FIG. 37, the signal representing the electrical resistance of a column of fluid or blood between the electrodes installed at connectors 106 and 128. Since the connectors are positioned fluidly much closer to the patient's blood vessels or fistula 134 than the blood pump 13, the dialyzer 14, and the air trap 122, signals related to the fluid path through the blood vessels or fistula 134 can distinguish between the straight column and the interrupted column of blood or fluid between the connectors 106 / 128 and the patient's blood vessels or fistula 134. The controller can be programmed to respond to the electrical resistance detected by the conductivity circuit that is found to exceed a predetermined value. Depending on the environment, the controller can then trigger an alarm warning the patient of a possible interruption in blood flow and optionally also command the closure 226 to stop the extracorporeal flow to and from the patient. Operation of the disconnection detection circuit FIG. 49 shows the test results using the cut detection circuit shown in FIG. 37 described above. In this case, a hemodialysis blood circuit and apparatus similar to those disclosed in U.S. Patent Application Publication Nos. 2009 / 0114582 and 2010 / 0056975 (the contents of which are incorporated herein by reference) were employed. The extracorporeal circuit 210 shown in FIG. 47 includes a blood pump 13, a dialyzer 14, an air trap 122, a venous blood circuit pipe 126, and an arterial blood circuit pipe 108. The extracorporeal circuit 210 fits into a hemodialysis device 220 similar to that shown in FIG. 48. The blood flow circuit to be tested includes a pair of membrane-based blood pumps disposed in the blood pump cassette 13 shown in FIG. 47, a dialyzer 14, a venous return air trap 122, an arterial blood tubing set 108, a venous blood tubing set 126, an arterial connector 106 and a venous connector 128, and a catheter tubing set 104, 130 connected to the vascular access needles 102, 132 as shown in FIG. 40. The needles 102, 132 were placed in a container holding anticoagulated bovine blood. The blood tubing sets 108 and 126 were approximately 6 feet long, and the catheter tubing sets 104 and 130 were approximately 2 feet long or less. The needles were alternately placed in or withdrawn from the container in the blood stream to simulate the cutting of the needle from the cannula or blood vessel. Periods A, C, and F in FIG. 49 represent the time the needles were immersed in the blood in the container. The electrical resistance measured by the cut detection circuit shown in FIG. 37 during these periods averaged between 120,000 ohms and 130,000 ohms. Periods B and E in FIG. 49 represent the time when the venous return needle 132 (under positive pressure from the blood pump) was withdrawn several centimeters above the surface of the blood in the container and the blood exiting the venous return needle formed a blood flow mixed with air as it entered the lower blood container. The electrical resistance measured during these periods averaged between 140,000 ohms and 150,000 ohms. Period D represents the time when one of the needles was completely removed from the container, creating a completely open electrical circuit. The electrical resistance measured during this period averaged between about 160,000 ohms and 180,000 ohms.Therefore, the controller can be readily programmed to identify the monitored resistance difference of the electrical circuit between an uninterrupted flow and an interrupted flow of blood. These results show that an interruption in the continuity of blood between the arterial needle 102 and the venous needle 132 can reliably result in a detectable change in the measured electrical resistance between two electrodes when they are placed relatively close to the arterial and venous access sites compared to the blood treatment components 13, 14, and 122 of the external blood circuit. Further, even a partial interruption in the continuity of blood flow (such as a flow of air through the blood), can be reliably detected even if the change in the measured electrical resistance is small. Closing section. As described above, using a closing section such as the closing section 513 of FIG. 17, the flow through the lines of the blood circuit assembly can be controlled, for example, at a location between the patient connection portions of the blood lines 203, 204 and the other parts of the assembly. Hereinafter, various aspects of the present invention related to the closing section, which can be employed alone or in any suitable combination with other features described herein, will be described together with one or more specific embodiments.

[0195] According to one aspect of the disclosed invention, a closure assembly is described that compresses at least one flexible tube, for example a pair of flexible tubes. The closure assembly comprises a tube closure portion that includes one or more flexible tubes and a mechanism configured to close the fluid flow in one or more pairs of flexible tubes in some embodiments. In some embodiments, the tube closure portion of the closure assembly comprises at least one closure member, and in a specific embodiment, comprises a closure member for each section of piping disposed within the assembly. In some such embodiments, each closure member is pressed or otherwise pushed or biased to a closed position by an element that slides along the side of the closure member, whereby the closure member pivots at its proximal end and translates towards the piping at its distal end. In one embodiment, the element is positioned between two closure members and acts to spread the distal ends of the closure members away from each other when the closure members are pressed against their respective tubes. In a preferred option, a main spring urges the spreading element towards the distal end of the closure element to a closed position. The spreading element can be moved manually through a button and link assembly connected to the spreading element or, similarly, under the control of a controller that actuates an actuator also connected to the spreading element, against the biasing force of the main spring, to a non-closed position near the proximal end of the closure element. A hinged door can be configured to cover the respective portions of the closure element and the piping. Actuation of the actuator can be blocked if the door does not close properly over the closure element. Optionally, a retainer element can be used to hold the spreading element in the non-closed position when the door is in the open position. By making the retainer element available, the spreading portion can be held in the non-closed position without the user continuously applying force to the button or by continuous actuation of the actuator. The retainer element can be made unavailable when the door is closed, whereby the spreading element can move freely to and from the closed position manually or through the actuator.

[0196] Figures 50 and 51 show perspective views of the deployment of the closure assembly 700 according to an embodiment of the present disclosure. Figure 50 shows a perspective view of the deployment of the closure assembly 700 from the front angle, and Figure 51 shows a perspective view of the deployment of the closure assembly 700 from the back angle.

[0197] The closure assembly 700 is configured to receive a pair of tubes 705 and close the tubes 705 using a pinching action at approximately the same level along the length of the assembly 700. The pinching action reduces the size of the internal fluid passage of each tube 705 to restrict the flow of the fluid flowing therethrough. The closure assembly 700 can be used with an infusion pump and in hemodialysis machines, hemodialysis, peritoneal dialysis, hemofiltration, hemodiafiltration, enterodialysis, etc.

[0198] The closure assembly 700 includes a frame 701. In some embodiments, the frame 701 includes tabs or snaps 709 that secure the frame to corresponding slots in the front panel of a blood filtration device such as a hemodialysis device.

[0199] The frame 701 includes an anvil or block 702 and 703 against which the tube 705 is compressed by the closed ends 713 of a pair of closing arms 710 and 711, and a tube guide 704 that positions each tube 705 relative to the blocks 702 and 703. The tube guide 704 and the blocks 702 and 703 are each configured to position the tube 705 at a predetermined position adjacent to each of the blocks 702 and 703. The closing assembly 700 also includes a door 706 pivotally mounted to the frame 701. The door 706 can be closed relative to the frame 701 to secure the tube 705 between each of the blocks 702 and 703 and the tube guide 704. Integrally formed with the door 706 is a latch 707 through an elastic flexible base (e.g., via a living hinge) 708 that secures the door 706 to the frame 701 in the closed position. However, the latch 707 can be arranged in other suitable ways, including a latch element that is adhered, welded, bolted, or otherwise attached to the door 706. As shown in FIGS. 50, 52, and 53, the door 706 can be opened by pressing the latch 707 laterally to release the catch 740 from engagement with the corresponding slot 741 in the frame 701.

[0200] The closing assembly 700 includes two arms 710 and 711. The first arm 710 has a pivot end 712 and a closed end 713. Similarly, the second arm 711 has a pivot end 714 and a closed end 715. The two arms 710 and 711 operate in concert to close the tube 705 when the button 716 is released and the door 706 is closed, or when the actuator 717 stops.

[0201] Figure 52 shows a front perspective view of the closure assembly 700 with the door 706 open and the button 716 pressed, showing the release of the closure arms 710 and 711 to enable loading and removal of the tube 705, according to one embodiment of the present disclosure. Figure 54 shows the front face of the closure assembly 700 of Figure 50 without the door 706 and the frame 701, showing the closure arms 710 and 711 that fully close the tubes 705a, b. As shown in Figure 54, the wedge element or spread 722 contacts the side facing the closure arms 710 and 711, and the closure arms 710 and 711 can be pressured under spring force to press the closure ends 713 and 715 of the closure arms 710 and 711 against a part of the tubes 705a, 705b. The user can release the closure arms 710 and 711 by pressing the button 716, whereby the spread 722 retracts away from the closure arms 710 and 711, releasing the pressure of the spread 722 applied to the distal ends of the closure arms 710 and 711. In some aspects, the manual actuator (e.g., button 716) acts as an override mechanism for an automatic actuator (e.g., a pneumatic piston / cylinder device, etc.) connected to the pipe closure element (e.g., spread 722). The manual actuator is operably connected to the pipe closure such that it provides a substantially linear movement of at least a part of the pipe closure, moving the closure member from the closed position to the non-closed position upon manual operation of the override mechanism by the user.

[0202] Similarly, by actuating the actuator to retract the spread portion 722 away from the closed ends 713, 715 of the closing arms 710 and 711, the closing arms 710 and 711 can be released. In one embodiment, as shown in FIG. 50, the spread portion 722 can be formed from, integrally molded with, attached to, or otherwise connected to the carriage assembly 723, and the carriage assembly 723 is further connected to the actuator's actuating arm (see, for example, FIGS. 56 and 57). The actuator can comprise, in particular, for example, a motor and gear assembly (such as a rack and pinion assembly or a worm gear assembly), a solenoid, a hydraulic cylinder, or a pneumatic cylinder. In a preferred embodiment, the actuator comprises a pneumatic cylinder 717 that linearly extends an actuating arm with a piston arm 742 against a spring force (which can be, for example, a coil spring 745 within the cylinder 717 as shown in FIG. 60). As shown in FIG. 60, in a side perspective view of the pneumatic actuating linear actuator 717, the piston arm 742 is connected to the carriage 723. When actuated pneumatically, the actuator 717 extends the piston arm 742 and moves the carriage 723 and the attached spread portion 722 in a direction that retracts the spread portion 722 from engagement with the distal ends 713, 715 of the closing arms 710 and 711 (for clarity, in particular, the closing arm 711, the frame 701, the door 706, the block 703, and the tube guide 704 have been removed from FIGS. 58 - 60). Preferably, a main spring external or internal to the cylinder / actuator 717 applies a biasing force to the piston arm 742 or the carriage 723 to move the closing arms 710 and 711 to the closed position with respect to the spread portion 722. When power or pneumatic pressure is lost, the closing arms 710 and 711 default to the closed mode and block the flow of fluid within the tube 705. As shown in the cross-sectional view of the closing assembly 700 of FIG. 60, in one embodiment, a coil spring 745 can be disposed within the cylinder 743 to provide a biasing force, and the piston 744 can move the piston arm 742 under pneumatic pressure against it.Air pressure can be supplied from a pressure source (e.g., a tank pressurized by a pump) that is regulated by an electromechanical valve intervening under the control of an electronic controller to the linear actuator 717.

[0203] As shown in FIGS. 54 and 59, when the linear actuator 717 fully retracts, the carriage 723 carries the spread portion 722 along the side facing the closing arms 710 and 711 and rotates them to the closed position. The first arm 710 pivots about its pivot end 712 to press the closing end 713 against the first tube 705a constrained by the block 702 (see FIG. 54). The second arm 711 pivots about its pivot end 714 so that the closing end 715 can press against the second tube 705 constrained by the block 703.

[0204] FIGS. 55 and 58 show the closing assembly 700 in the non-closed state (for clarity, the frame 701, door 706, blocks 702, 703 and other elements have been removed). When the button 716 is pressed or the linear actuator 717 is activated, the carriage 723 and the attached spread portion 722 move distally away from the actuator 717, allowing the closing portion arms 710 and 711 to rotate to the non-closed position about the pivot points 712 and 714. Due to the elasticity of the tubes 705a, b, the arms 710 and 711 can pivot towards each other. In some embodiments of the present disclosure, small magnets (not explicitly shown) embedded in the arms 710 and 711 pull the arms 710 and 711 towards each other, facilitating the retraction of the closing ends 713 and 715 away from the tubes 705. In other embodiments, a small spring (not shown) can bias the closing arms 710 and 711 to pivot towards each other, and the spring constant is weak enough to be overcome by the main spring (e.g., spring 745) that biases the carriage 723 or the spread portion 722 to the retracted (closed) position.

[0205] FIG. 53 shows a side perspective view of the closure assembly 700 of FIG. 50 (with the frame 701 removed for clarity) showing the state of engagement with the switch 720 when the door 706 is closed. As shown in FIG. 53, the hinge portion 708 of the latch 707 is connected to an engagement member or catch 740 that can fit into an interlocking slot 741 of the frame 701 (see, e.g., FIGS. 50 and 53). When the door 706 is closed, a portion of the catch 740 of the latch 707 of the door 706 engages with the spring-loaded switch 720, and in one embodiment, the spring-loaded switch 720 includes a spring arm 737 of the switch 720.

[0206] Engagement of the switch 720 by closing of the door 706 notifies an electronic controller (not shown) that the door 706 is properly closed and that the closure portions 710 and 711 can be released to allow fluid to flow through the tube 705 by actuating the linear actuator 717. The controller can also perform other functions, such as commanding a pump connected to the tube 705 to disclose pumping of fluid within the tube 705, for example, in response to a door 706 closed signal.

[0207] FIG. 56 shows the rear of the closure assembly 700 of FIG. 50 with the linear actuator 717 in its fully retracted position (i.e., the closed position) according to an embodiment of the present disclosure. FIG. 56 shows the same configuration as shown in the front view of the closure assembly 700 in FIG. 54, but shows the rear side of the closure assembly 700. FIG. 56 shows some of the operating parts of the closure assembly 700 of FIG. 50 to illustrate the operation of the actuator 717 and the carriage 723. The carriage 723 moves by extension or retraction of the piston arm 742 or by actuation of the button 716. The carriage 723 includes a guide 724 that is integrally formed with or otherwise attached to the carriage 723. The guide 724 guides the carriage 723 as it moves via actuation of the piston arm 742 or by actuation of the button 716. The guide 724 interfaces with a track 725 of the frame 701 (see, e.g., FIG. 51).

[0208] In any embodiment, when the door 706 is opened, the carriage 723 and the spread portion 722 are moved to the unclosed position by the actuation of the button 716 by the user or the actuation of the actuator 717 by the controller, and the retainer element or assembly can hold the unclosed position without further force being applied by the user or by the actuator 717. In the exemplary embodiment shown in FIG. 56, the carriage 723 can incorporate a latch pin 726 that interlocks with the slot or hole of the holding member 718. The holding member 718 has a surface 727 positioned such that the pin 738 located inside the closed door 706 contacts it (see, for example, FIGS. 51 and 52). The through hole 739 allows the pin 738 to contact a part of the holding member 718 and displace it in the rearward direction. In the illustrated embodiment, the pin 738 contacts the front plate 727 of the holding member 718. The holding member 718 also has a surface with a slot or hole 729 positioned to receive the head of the latch pin 726, which forms the receiving portion 729 in the illustrated embodiment. The holding member 718 is configured to slide within a groove or guide (not shown) of the frame 701 in response to contact by the pin 738 when the door 706 closes or opens (see, for example, FIG. 51). A spring 730 mounted on the frame 701 can bias the holding member 718 forward to the stopper mechanism (not shown) of the frame 701, such that when the door 706 is opened, the holding member 718 can slide forward and realign the receiving portion 729 with respect to the latch pin 726. When the door 706 closes (see FIGS. 50 and 51), the pin 738 of the door 706 presses against the front plate 727, and the front plate 727 compresses the spring 730, whereby the receiving portion 729 of the horizontal plate 728 is positioned directly over the latch pin 726. When the receiving portion 729 is aligned with the latch pin 726, the area of the receiving portion 729 is wide enough to release the latch pin 726 by the holding member 718, whereby the carriage 723 can receive the spring force of the main spring 745 in the actuator 717.Thereafter, when no air pressure is applied to the actuator 717, the carriage 723 can freely move to the closed position. By the holding member 718 in the inoperative state (i.e., the non-operating state), the latch pin 726 can freely move through the receiving portion 729 when the carriage 723 moves between the fully extended position and the fully retracted position.

[0209] FIG. 57 is a rear view of the closing assembly 700 with the piston arm 742 in the extended position such that the actuator 717 is actuated to bring the closing arms 710, 711 to the non-closed state. In this figure, the head of the latch pin 726 is shown to be above the plane of the horizontal plate 728 of the holding member 718, and the recessed region 731 of the latch pin 726 is shown to be aligned with the receiving portion 729 of the holding member 718. In this figure, the door 706 is in the closed position, which means that the receiving portion 729 is in a sufficiently rearward position so that the latch pin 726 does not catch within the holding member 718.

[0210] When the door 706 is fully opened, the pin 738 of the door 706 does not press the front plate 727, and the spring 730 applies a force to the front plate 727, whereby the receiving portion 729 of the holding member 718 is positioned such that the latch pin 726 can engage with the edge of the receiving portion 729 and be hooked on the holding member 718. When the receiving portion 729 is positioned to be hooked on the latch pin 726, the latch pin 726 moves into the receiving portion 729 and pulls the front plate 727 backward against the force of the spring 730. When the head of the latch pin 726 has moved sufficiently through the receiving portion 729, the recessed region 731 below the head of the latch pin 726 is aligned with the horizontal plate 728 which moves when the edge of the receiving portion 729 moves into the recessed region 731 under the force of the spring 730 applied to the front plate 727. When the pin 738 of the door 706 is fully engaged with the front plate 727, the receiving portion 729 is positioned to release the latch pin 726 from the latch 718. Thus, when the door 706 is opened, the carriage 723 and the spread portion 722 can be held in the unclosed position without continuous application of force by the actuator 717 or by the user pressing the button 716. Thereby, the user can load and remove pipes from the closing assembly 700 without simultaneously applying force to the button 716. However, when the door 706 is closed, the holding member 718 is no longer operable, and without continuous application of force by the actuator 717 or via the button 716, the carriage 723 and the spread portion 722 move into place and rotate the closing arms 710 and 711 to the closed position.

[0211] Figures 58 and 59 show perspective side views of some of the operating parts of the closing assembly 700 of FIG. 50, with the frame 701, blocks 702, 703, tube guide 704, door 706, closing arms 711 and other parts removed for clarity. In FIG. 58, the piston arm 742 is fully extended according to an embodiment of the present disclosure. FIG. 58 shows the latch pin 726 hanging on the retaining member 718. That is, assuming the door 706 is in the open position, the horizontal plate 728 is positioned by the force of the spring 730 to engage the recessed area 731 of the latch pin 726.

[0212] FIG. 59 shows a perspective side view of the closing assembly 700 of FIG. 50 with the piston arm 742 in the fully retracted position, with some elements removed as in FIG. 58 for clarity. In this example, the latch pin 726 is shown as being completely removed from the retaining member 718, and in the absence of an operating force on the actuator 717 or a pressing force on the button 716, the piston arm 742, carriage 723 and spreader 722 can freely retract under the force of the main spring 745 (see FIG. 60) biased against the extension of the piston arm 742. The spreader 722 then moves towards the closing ends 713, 715 of the closing arms 710, 711. In one embodiment, as shown in FIGS. 58 and 59, when the button 716 is pressed, the button 716 pivots about the pivot axis 732 to raise the lever arm 733. The lever arm 733 is pivotally connected to the connecting member 734 through the proximal pivot axis 735. The connecting member 734 is then pivotally connected to the carriage 723 through the distal pivot axis 736. When the button 716 is pressed or the piston arm 742 moves the carriage 723 towards the retaining member 718, as shown in FIG. 58, the connecting member 734 moves with the carriage 723 and rotates the button 716 about the pivot axis 732.

[0213] FIG. 61 shows the closure assembly 700 of FIG. 50 used in the front panel assembly 911 of a dialysis system according to an embodiment of the present disclosure. The closure assembly 700 closes the flexible tubes 901, 902 through which blood flows to and from the patient. The right tube 902 conveys blood from the patient to the blood pump assembly 1000 (arterial blood line), and the left tube 901 conveys blood to return to the patient after passing through the air trap 19 from the dialysis machine 14 (venous blood line). The closure assembly 700 can close the blood flow passing through both of these patient tubes 901, 902 simultaneously.

[0214] As described in detail above, the tubes 901, 902 are connected to a blood pump cassette or assembly 1000, which is a modular unit that can be mounted on and removed from the front panel 911. The patient tubes 901, 902 can both be provided as an assembly including the blood pump cassette 1000 and the air trap 19, and can be loaded into the closure assembly 700 when the blood pump cassette 1000 is mounted on the front panel 911. In this embodiment, the closure assembly 700 forms a permanent part of the front panel 911.

[0215] When the closure assembly 700 is in the open state, the pump located in the blood pump cassette 1000 can be operated to pump blood from the patient through the right tube 902, through the blood pump, and through the dialyzer 14. The blood processed by the dialyzer 14 then returns to the patient through the tube 901 after first passing through the air trap 19 and the in-line air detector 823.

[0216] The following are hereby incorporated by reference in their entirety: U.S. Provisional Patent Application No. 60 / 903,582, filed February 27, 2007, entitled "Hemodialysis System and Methods"; U.S. Provisional Patent Application No. 60 / 904,024, filed February 27, 2007, entitled "Hemodialysis System and Methods"; U.S. Patent Application No. 11 / 787,213, filed April 13, 2007, entitled "Heat Exchange System, Devices and Methods"; "Fluid Pumping Systems, Devices U.S. Patent Application No. 11 / 787,212, filed on April 13, 2007, entitled "Thermal and Conductivity Sensing Systems, Devices and Methods", U.S. Patent Application No. 11 / 787,112, filed on April 13, 2007, entitled "Thermal and Conductivity Sensing Systems, Devices and Methods", U.S. Patent Application No. 11 / 871,680, filed on October 12, 2007, entitled "Pumping Cassette", U.S. Patent Application No. 11 / 871,712, filed on October 12, 2007, entitled "Pumping Cassette", U.S. Patent Application No. 11 / 871,787, filed on October 12, 2007, entitled "Pumping Casette", U.S. Patent Application No. 11 / 871,793, filed on October 12, 2007, entitled "Pumping Cassette", and U.S. Patent Application No. 11 / 871,803, filed on October 12, 2007, entitled "Cassette System Integrated Apparatus". Further, the following is hereby incorporated by reference in its entirety into this specification.That is, U.S. Patent No. 4,808,161, issued February 28, 1989, entitled "Pressure-Measurement Flow Control System"; U.S. Patent No. 4,826,482, issued May 2, 1989, entitled "Enhanced Pressure Measurement Flow Control System"; U.S. Patent No. 4,976,162, issued December 11, 1990, entitled "Enhanced Pressure Measurement Flow Control System"; U.S. Patent No. 5,088,515, issued February 18, 1992, entitled "Valve System with Removable Fluid Interface"; and U.S. Patent No. 5,350,357, issued September 27, 1994, entitled "Peritoneal Dialysis Systems Employing a Liquid Distribution and Pumping Cassette that Emulates Glavity Flow". Also incorporated herein by reference are U.S. Patent Application No. (Docket No. F63, now U.S. Patent Application Publication No. 12 / 038,474), filed on the same date as this application and entitled "Sensor Apparatus Systems, Devices and Methods", and U.S. Patent Application No. (Docket No. F62), filed on the same date as this application and entitled "Cassette System Integrated Apparatus".

[0217] Although various embodiments of the present invention have been described and explained in this specification, those skilled in the art can easily conceive of various other means and / or structures for performing the functions described in this specification and / or obtaining the results and / or one or more advantages described in this specification. Such conceptions and / or modifications are considered to fall within the scope of the present invention. That is, those skilled in the art can easily recognize that all the parameters, dimensions, materials, and configurations described in this specification are examples, and the actual parameters, dimensions, materials, and / or configurations are determined by the specific applications in which the present invention is used. Those skilled in the art can recognize many equivalents of the specific embodiments of the present invention described in this specification by using experiments. Therefore, it should be understood that the above-described embodiments are merely illustrative, and the present invention can be implemented within the scope of the appended claims and their equivalents.

[0218] As used in this specification and the claims, the indefinite articles "a" and "an" should be understood to mean "at least one" unless it is clearly stated to the contrary. 1. A drainage cassette that can be connected to and disconnected from the front panel of the dialysis unit by a user of the dialysis unit, a venous connection port connected to a venous blood line connector that is the end point of the venous line of the blood circuit assembly and in fluid communication with the venous blood line connector; an arterial connection port connected to an arterial blood line connector that is the end point of the arterial line of the blood circuit assembly and in fluid communication with the arterial blood line connector; a fluid channel that fluidly connects the venous connection port and the arterial connection port; a drainage outlet port in fluid communication with the fluid channel and configured to be removably coupled to a drainage connector on the front panel of the dialysis unit; and a valve configured to control the flow in the fluid channel. The drainage cassette is detachable from the front panel, and the valve is configured to controllably open and close the fluid communication of the fluid channel between the drainage outlet port and the venous connection port, or to controllably open and close the fluid communication of the fluid channel between the drainage outlet port and the arterial connection port, and to control in the fluid channel, a drainage cassette. 2. The drainage cassette according to 1., further comprising a main body forming the arterial connection port, the venous connection port, and the fluid channel. 3. The drainage cassette according to 1., further comprising a check valve configured to allow flow from the fluid channel and from the drainage outlet port and to prevent flow from the drainage outlet port to the fluid channel. 4. The valve is a pneumatic control valve, The drainage cassette according to 1., further comprising a pneumatic control port configured to detachably fit with a port of the front panel and fluidly connected to the valve to enable control of the valve by the dialysis unit. 5. The drainage cassette according to 1., further comprising a latch configured to releasably lock the drainage cassette to the front panel. 6. The drainage outlet port of the drainage cassette according to 1. is in fluid communication with the fluid channel at a location above the location where the arterial connection port and the venous connection port communicate with the fluid channel. 7. The fluid channel of the drainage cassette according to 1. is U-shaped. 8. In the drainage cassette according to 7., the arterial connection port and the venous connection port are fluidly connected to the fluid channel at the ends of the U-shape, and the drainage outlet port is fluidly connected to the fluid channel at the central bend of the U-shape. 9. The drainage cassette according to 1., further comprising a conductivity sensor configured to detect the conductivity of the fluid in the fluid channel. 10. The drainage cassette according to 1., further comprising a temperature sensor configured to detect the temperature of the fluid in the fluid channel. 11. The drainage cassette according to 1., further comprising one or more sensors configured to detect the characteristics of the fluid in the fluid channel, the one or more sensors being connected to an electrical connector. 12. The electrical connector is configured to electrically connect the one or more sensors to a corresponding electrical connector on the front panel. Optionally, the electrical connector and the drainage outlet port are configured to be simultaneously connected in a single connection operation to a corresponding electrical connector and a drainage connector on the front panel of the dialysis unit. The valve is a pneumatic control valve. The cassette The drainage cassette according to 11., further comprising a pneumatic control port configured to removably fit with a control port on the front panel, the pneumatic control port being configured to be simultaneously connected in a single connection operation to a corresponding control port. 13. The drainage outlet port is permanently open and in fluid communication with the arterial connection port, and the valve is configured to controllably open and close fluid communication in the fluid channel between the drainage outlet port and the venous connection port, as described in 1. 14. The drainage outlet port is permanently open and in fluid communication with the venous connection port, and the valve is configured to controllably open and close fluid communication in the fluid channel between the drainage outlet port and the arterial connection port, as described in 1. 15. A blood circuit assembly and a drainage cassette for a dialysis unit, the blood circuit assembly A pair of pneumatic pumps that circulate blood received from a patient through a circuit including a dialyzer unit and returned to the patient, the pneumatic pumps having pneumatic control ports, the pneumatic control ports being configured to be aligned and fitted by engaging a corresponding port located on the front panel of the dialysis unit and pressing the control port against the corresponding port by mounting the blood circuit assembly on the front panel, a pair of pneumatic pumps, An air trap configured to remove air from the blood circulating within the circuit, A pair of dialyzer connectors configured to connect to the inlet and outlet of the dialyzer unit, A pair of blood line connectors including an arterial blood line connector that receives blood from the patient and supplies the blood to the pneumatic pump and a venous blood line connector that returns the blood to the patient. The drainage cassette, A venous connection port connected to the venous blood line connector and in fluid communication with the venous blood line connector, An arterial connection port connected to the arterial blood line connector and in fluid communication with the arterial blood line connector, A fluid channel fluidly connecting the venous connection port and the arterial connection port, A drainage outlet port in fluid communication with the fluid channel and configured to be detachably coupled to a drainage connector on the front panel of the dialysis unit, A valve configured to control the flow in the fluid channel. The blood circuit assembly and the drainage cassette are both engageable with the front panel for operation in dialysis treatment and detachable from the front panel for replacement, an assembly and a cassette. 16. The valve is configured to controllably open and close the fluid communication of the fluid channel between the drainage outlet port and the venous connection port, or to controllably open and close the fluid communication of the fluid channel between the drainage outlet port and the arterial connection port, and to control in the fluid channel, the blood circuit assembly and cassette according to 15. 17. The blood circuit assembly and cassette according to 15. further comprising a main body forming the arterial connection port, the venous connection port and the fluid channel. 18. The blood circuit assembly and cassette according to 15. further comprising a check valve configured to allow flow out of the fluid channel and out of the drainage outlet port and to prevent flow from the drainage outlet port to the fluid channel. 19. The valve is a pneumatic control valve, The cassette according to 16. further comprising a pneumatic control port configured to detachably fit with the port of the front panel and fluidly connected to the valve to enable control of the valve by the dialysis unit. 20. The blood circuit assembly and cassette according to 15. further comprising a latch configured to releasably lock the drainage cassette to the front panel. 21. The drainage outlet port fluidly communicates with the fluid channel at a location above where the arterial connection port and the venous connection port communicate with the fluid channel, the blood circuit assembly and cassette according to 15. 22. The fluid channel is U-shaped, the blood circuit assembly and cassette according to 15. 23. The arterial connection port and the venous connection port are fluidly connected to the fluid channel at the ends of the U-shape, and the drainage outlet port is fluidly connected to the fluid channel at the central bend of the U-shape, the blood circuit assembly and cassette according to 22. 24. The blood circuit assembly and cassette according to 15., further comprising a conductivity sensor configured to detect the conductivity of the fluid in the fluid channel. 25. The blood circuit assembly and cassette according to 15., further comprising a temperature sensor configured to detect the temperature of the fluid in the fluid channel. 26. The blood circuit assembly and cassette according to 15., further comprising one or more sensors configured to detect the characteristics of the fluid in the fluid channel. 27. The one or more sensors are connected to an electrical connector, and the electrical connector is configured to mate with a corresponding electrical connector on the front panel when the drain outlet port is connected to the drain connector. The blood circuit assembly and cassette according to 26. 28. The electrical connector and the drain outlet port are configured to be simultaneously connected in a single connection operation to corresponding electrical and drain connectors on the front panel of the dialysis unit. The blood circuit assembly and cassette according to 27. 29. The valve is a pneumatic control valve. The cassette according to 28., further comprising a pneumatic control port configured to removably mate with a control port on the front panel. 30. The drain outlet port is permanently open and in fluid communication with the arterial connection port, and the valve is configured to controllably open and close fluid communication in the fluid channel between the drain outlet port and the venous connection port. The blood circuit assembly and cassette according to 15. 31. The drain outlet port is permanently open and in fluid communication with the venous connection port, and the valve is configured to controllably open and close fluid communication in the fluid channel between the drain outlet port and the arterial connection port. The blood circuit assembly and cassette according to 15.

Claims

**Claim 1**: A hemodialysis system comprising: A dialysis unit configured to perform hemodialysis, A dialyzer, An air-driven blood pump configured to pump blood through the dialyzer, An equilibrium circuit comprising an air-driven dialysate pump for controlling the flow of dialysate through the dialyzer, wherein the flow of blood and dialysate through the dialysis unit is controlled by a plurality of pneumatic actuating valves; and a dialysis unit comprising the equilibrium circuit, A power unit configured to provide pneumatic power to operate the blood pump, the dialysate pump, and the plurality of valves, A housing, A first positive pressure tank, A negative pressure tank, A compressor fluidly connected to the first positive pressure tank, A dehumidifier downstream of the compressor, A metal tube fluidly connected to the compressor, A cooler for cooling the metal tube, A water trap fluidly connected to the metal tube downstream of the compressor and upstream of the first positive pressure tank; and a power unit comprising the dehumidifier, The first positive pressure tank and the negative pressure tank are present in the housing, the housing is removably connected to the dialysis unit, and the power unit has a power conduit and two or more pneumatic lines configured to connect to the dialysis unit. A hemodialysis system. **Claim 2**: The hemodialysis system according to claim 1, wherein the power unit further comprises a vacuum pump fluidly connected to the negative pressure tank. **Claim 3**: The power unit, A first control system for controlling the compressor to achieve a predetermined first positive pressure in the first positive pressure tank, A second control system for controlling the vacuum pump to achieve a predetermined negative pressure in the negative pressure tank. The hemodialysis system according to claim 2, further comprising: **Claim 4**: The power unit, A positive pressure regulator fluidly connected to the first positive pressure tank and set to a second positive pressure less than the first positive pressure; and a positive pressure regulator, A second positive pressure tank fluidly connected to the first positive pressure tank via the positive pressure regulator, The hemodialysis system according to claim 3, wherein the power unit has three or more pneumatic lines configured to connect to the dialysis unit.

5. The hemodialysis system according to claim 1, wherein the cooler includes a Peltier cooling element, a finned heat exchanger, and a fan.

6. The hemodialysis system according to claim 3, wherein the first positive pressure is in the range of 1000 to 1100 mmHg.

7. The hemodialysis system according to claim 3, wherein the first positive pressure is in the range of 700 to 850 mmHg.

8. The hemodialysis system according to claim 3, wherein the negative pressure is -400 to -450 mmHg.

9. The hemodialysis system according to claim 4, wherein the first positive pressure is in the range of 1000 - 1100 mmHg, and the second positive pressure is in the range of 700 to 850 mmHg.

10. The hemodialysis system according to claim 3, wherein the first control system includes a pressure sensor fluidly connected to the first positive pressure tank and a relay for controlling the compressor, and controls the pressure in the first positive pressure tank.

11. The hemodialysis system according to claim 10, wherein the first control system turns on the compressor when the pressure measured by the pressure sensor falls below the first positive pressure by a predetermined value, and turns off the compressor when the pressure measured by the pressure sensor exceeds the first positive pressure by a predetermined value.

12. The hemodialysis system according to claim 10, wherein the first control system drives the compressor with a pulse width modulation signal and controls the compressor with a proportional integral derivative controller.

13. The hemodialysis system according to claim 1, wherein the housing is removably connected to the dialysis unit by a single handle operation.

14. The system according to claim 13, wherein the handle is a manually operable connection handle.

15. A hemodialysis system, A dialysis unit configured to perform hemodialysis, A dialyzer, A pneumatically driven blood pump configured to pump blood through the dialyzer, An equilibrium circuit including a pneumatically driven dialysate pump for controlling the flow of dialysate through the dialyzer, wherein the flow of blood and dialysate through the dialysis unit is controlled by a plurality of pneumatically actuated valves, and the dialysis unit includes the equilibrium circuit. A power unit configured to provide pneumatic power for operating the blood pump, the dialysate pump, and the plurality of valves, a housing, a compressor, a first positive pressure tank, a dehumidifier fluidly connected between the compressor and the first positive pressure tank, a metal tube fluidly connected to the compressor, a cooler for cooling the metal tube, a power unit comprising a dehumidifier including a water trap fluidly connected to the metal tube downstream of the compressor and upstream of the first positive pressure tank, wherein the first positive pressure tank, the compressor, and the dehumidifier are present in the housing, the housing is removably connected to the dialysis unit, and the power unit has a power pipeline and two or more pneumatic lines configured to connect to the dialysis unit, a hemodialysis system.

16. The hemodialysis system according to claim 15, wherein the cooler comprises a Peltier cooling element, a finned heat exchanger, and a fan.

17. The hemodialysis system according to claim 15, further comprising a negative pressure tank and a vacuum pump fluidly connected to the negative pressure tank.

18. The power unit of the hemodialysis system according to claim 15 further comprises a positive pressure regulator fluidly connected to the first positive pressure tank, wherein the first positive pressure tank is characterized by a first positive pressure, and the positive pressure regulator is set to a second positive pressure that is less than the first positive pressure, and a second positive pressure tank fluidly connected to the first positive pressure tank via the positive pressure regulator. The power unit has three or more pneumatic lines configured to connect to the dialysis unit.

15. The hemodialysis system according to claim 15, wherein the housing is removably connected to the dialysis unit by a single handle operation.

19. The hemodialysis system according to claim 15, wherein the handle is a manually operable connection handle. ​ ​ ​ ​

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