Patent Description:
Hemodialysis and hemofiltration systems circulate blood and dialysis solution through a dialyzer having a filter membrane separating blood and dialysis solution. Toxins and metabolic waste products are exchanged through the dialyzer membrane between the dialysis solution and the blood circulating through the dialyzer.

These treatments are administered using PD and hemodialysis systems, which may include a controlled flow path for transporting fluids used during a therapy session. One or more of the following solutions may be supplied to the patient: a peritoneal dialysis fluid, a priming solution, a physiologically compatible solution for contacting blood, a physiologically compatible solution for infusion to a subject, a solution for blood rinse back to a subject, and the like.

PD systems include machines, which are also referred to as "cyclers", are designed to automatically infuse, dwell, and drain dialysis solution to and from the patient's peritoneal cavity in a process referred to as "continuous cycler-assisted peritoneal dialysis" (CCPD). The treatment typically lasts for several hours, often beginning with an initial drain procedure to empty the peritoneal cavity of used or spent dialysis solution. The sequence then proceeds through the succession of infusion, dwell, and drain phases that follow one after the other. Each phase is called a cycle.

Due to the length of the treatment, the large size of the PD machine and the large volume of dialysis solution required for the treatment, the treatment may be performed at home while the patient sleeps. Although nighttime CCPD treatments are sufficient for some patients, other patients require one or more additional fluid exchanges during the daytime. To permit the patient to participate in normal daily activities outside of the home, continuous ambulatory peritoneal dialysis (CAPD) is performed by connecting a bag of dialysis fluid to the patient's peritoneal catheter, and delivering about <NUM>-<NUM> liters of dialysis solution to the peritoneal cavity. After permitting the dialysis solution to dwell in the peritoneal cavity for a predetermined period of time, the dialysis solution is drained from the peritoneal cavity.

Since these fluids may be directly introduced into a human body and/or contacts blood through the membrane, the fluids are required to be free of biological and chemical contaminants. Thus, single use fluid lines and cassettes are used to minimize contamination during treatment. There is a need for novel cassettes configured to move large amounts of fluids efficiently.

Relevant prior art is for instance disclosed in documents <CIT> and <CIT>.

The present disclosure provides a fluid cassette for use with PD systems. In embodiments, certain features of the cassette may be incorporated into cassettes for use with hemodialysis systems and other systems used in blood treatment.

According to one embodiment of the present disclosure a dialysis cassette is disclosed. The dialysis cassette includes a cassette housing having a plurality of channels fluidly coupled to a plurality of connectors and a plurality of valves disposed within the plurality of channels. The dialysis cassette also includes a pump assembly disposed within the cassette housing. The pump assembly includes a pump housing and a flexible rotor having a plurality of flexible vanes, where the flexible rotor is rotatable in either a clockwise direction or a counterclockwise direction to move a fluid through the plurality of channels.

Implementations of the above embodiment may include one or more of the following features. The pump housing may include an inlet and an outlet coupled to the plurality of channels, and a narrowing portion disposed between the inlet and the outlet. The flexible vanes may be configured to compress when contacting the narrowing portion. The flexible rotor may include an elastomer and a thermoplastic polymer. The flexible rotor may be rotatable about a rotation axis perpendicular to a plane defined by the cassette housing. The pump housing may include a drive shaft and a gasket disposed about the drive shaft. The gasket may be configured to fluidly seal the pump housing. Each of the plurality of valves may be a pinch valve having an undulating shape with a deflectable portion. The cassette housing may further include one or more sensors disposed in fluid contact with the plurality of channels. The sensors may be a pressure sensor, a temperature sensor, a conductivity sensor, or an air bubble detector.

According to another embodiment of the present disclosure a dialysis system is disclosed. The dialysis system includes a peritoneal dialysis cycler having a cassette interface, a patient line, a drain line, and a fluid source. The dialysis system also includes a cassette configured to couple to the cassette interface, the patient line, the drain line, and the fluid source. The cassette includes a plurality of channels fluidly coupled to a plurality of connectors each of which is coupled to a respective one of the patient line, the drain line, and the fluid source. The cassette also includes a plurality of valves, each valve of the plurality of valves disposed within a respective channel of the plurality of channels. The cassette further includes a pump assembly disposed within the cassette housing. The pump assembly includes a pump housing and a flexible rotor including a plurality of flexible vanes, where the flexible rotor is rotatable in either a clockwise direction or a counterclockwise direction to move a fluid through the plurality of channels.

Implementations of the above embodiment may include one or more of the following features. The pump housing may include an inlet and an outlet coupled to the plurality of channels, and a narrowing portion disposed between the inlet and the outlet. The plurality of flexible vanes may be configured to compress when contacting the narrowing portion. The flexible rotor may include an elastomer and a thermoplastic polymer. The flexible rotor may be rotatable about a rotation axis perpendicular to a plane defined by the cassette housing. The pump housing may include a drive shaft and a gasket disposed about the drive shaft. The gasket may be configured to fluidly seal the pump housing. Each valve of the plurality of valves may be a pinch valve having an undulating shape with a deflectable portion. The cassette interface may include a plurality of actuators configured to push on the deflectable portion. The cassette housing may further include one or more sensors disposed in fluid contact with the plurality of channels. The one or more sensors may include one of a pressure sensor, a temperature sensor, a conductivity sensor, or an air bubble detector.

A dialysis system according to the present invention comprises the technical features of independent claim <NUM>.

Embodiments of the present disclosure are described herein with reference to the accompanying drawings, wherein:.

With reference to <FIG>, a peritoneal dialysis (PD) system <NUM> includes a PD cycler <NUM> and a PD fluid cassette <NUM>. The PD cycler <NUM> and the PD cassette <NUM> are used to provide continuous cycler-assisted peritoneal dialysis. The PD cycler <NUM> may be used in a home environment. Due to its size and weight, the PD cycler <NUM> may be supported on a cart <NUM> that is used to improve ease of handling and storage of the PD cycler <NUM>. The PD cycler <NUM> includes a housing <NUM>, a door <NUM>, and a cassette interface <NUM> that abuts an inner portion <NUM> the PD cassette <NUM> when the PD cassette <NUM> is disposed within a cassette compartment <NUM> formed between the cassette interface <NUM> and the closed door <NUM>. A heater tray <NUM> may be positioned on top of the housing <NUM>. The heater tray <NUM> is sized and shaped to accommodate a bag of dialysis solution (e.g., a <NUM> liter bag of dialysis solution). The PD cycler <NUM> also includes a display screen <NUM> and control buttons <NUM>. In embodiments, the display screen <NUM> may be a touchscreen. The display screen <NUM> and control buttons <NUM> may be operated by a user (e.g., a patient) to allow, for example, set-up, initiation, and/or termination of a PD treatment.

Dialysis solution storage bags <NUM> may be suspended from the sides of the cart <NUM>, and a dialysis solution fill bag <NUM> is positioned on the heater tray <NUM>, as shown in <FIG>. The storage bags <NUM> and the fill bag <NUM> are connected to the PD cassette <NUM> via storage bag lines <NUM> and a fill bag line <NUM>, respectively. The storage bag lines <NUM> may be used to pass dialysis solution from storage bags <NUM> to the PD cassette <NUM> during use, and the fill bag line <NUM> may be used to pass dialysis solution back and forth between the PD cassette <NUM> and the fill bag <NUM> during use. In addition, a patient line <NUM> and a drain line <NUM> are connected to the PD cassette <NUM>. The patient line <NUM> may be connected to a patient's abdomen via a catheter and may be used to pass dialysis solution back and forth between the PD cassette <NUM> and the patient during use. The drain line <NUM> may be connected to a drain or drain receptacle and may be used to pass dialysis solution from the PD cassette <NUM> to the drain or drain receptacle during use.

Referring to <FIG>, the PD cassette <NUM> includes a cassette housing <NUM> formed from an inner portion <NUM> and an outer portion <NUM>. The entirety or a segment of the inner portion <NUM> may be formed from single or multiple layer flexible membrane <NUM> (<FIG>). In embodiments, the flexible membrane <NUM> may be formed from polyvinyl chloride, polypropylene, silicone rubber, ethylene propylene diene monomer rubber, and the like. The inner portion <NUM> contacts the cassette interface <NUM> once the PD cassette <NUM> is loaded into the cassette compartment <NUM> of the PD cycler <NUM>. The outer portion <NUM> may be formed from a rigid material and contacts the door <NUM> once the PD cassette <NUM> is loaded into the cassette compartment <NUM> of the PD cycler <NUM>. The outer portion <NUM> may be formed from a thermoplastic polyester including, but not limited to, polyethylene terephthalate glycol, high-density polyethylene, polyvinyl chloride, polyethylene terephthalate glycol, and combinations thereof. The outer portion <NUM> may be transparent. The outer portion <NUM> defines a plurality of fluid channels <NUM>, which are fluidly coupled to a plurality of fluid line connectors 208a, 208b, 208c, which act as inlet/output ports of the PD cassette <NUM>.

The fluid channels <NUM> are fluidly coupled to a plurality of sensor portions, which may be larger than the fluid channels <NUM> and may be of various shapes (e.g., cylindrical, circular, etc.) to accommodate sensors within the PD cassette <NUM>. As shown in <FIG>, the PD cassette <NUM> includes a plurality of sensors, namely, a first pressure sensor <NUM>, a second pressure sensor <NUM>, a temperature sensor <NUM>, a conductivity sensor <NUM>, and an air bubble detector <NUM>. These sensors are used to monitor pressure, temperature, conductivity, and presence of air bubbles in the dialysis fluid, respectively.

With reference to <FIG>, pressure sensors <NUM> and <NUM> may be pressure transducers. Only the pressure sensor <NUM> is shown for simplicity. The pressure sensor <NUM> includes a contact pad 270a biased by a spring 270b and coupled to a pressure transducer. The contact pad 270a is in physical contact with the flexible membrane <NUM> and as the membrane <NUM> is deflected due to increased pressure of the dialysate flowing through the channel <NUM>, the contact pad 270a is pushed away, thereby acting on the pressure transducer, which measures the pressure within the fluid channel <NUM>.

The temperature sensor <NUM> and the conductivity sensor <NUM> may be disposed in a single compartment <NUM>. Conductivity sensor <NUM> may include two pairs of electrodes and is configured to determine conductivity by applying an electric current to a first pair of electrodes, while measuring the current through a second pair of electrodes. Conductivity is calculated based on measured current using the distance, surface area, and resistance of the electrodes. Temperature sensor <NUM> may be a thermocouple, a contactless infrared ("IR") sensor, or any other suitable temperature sensor. With reference to <FIG>, the temperature sensor <NUM> is shown as an IR sensor, which includes an emitter configured to emit IR light and a receiver configured to measure reflected IR light and measure the temperature through the membrane <NUM>. The a portion or the entirety of the membrane <NUM> is transparent to IR light such that the temperature sensor <NUM> can irradiate the dialysate through the membrane <NUM>.

The air bubble detector <NUM> may be an acoustic and/or an optical bubble detector and is configured to detect the presence of air bubbles in the fluid based on disruption in the acoustic and/or optical signals transmitted through the fluid.

The PD cassette <NUM> includes a plurality of valves 250a-m disposed within fluid channels <NUM>, which direct dialysis solution through the PD cassette <NUM>. The PD cassette <NUM> also includes an integrated pump assembly <NUM> having a pump housing <NUM>, which consists of a first pump housing portion <NUM> integrally formed as part of the outer portion <NUM> and a second pump housing portion <NUM> extending from the inner portion <NUM> (<FIG>). During operation, the dialysis solution flows through the pump assembly <NUM> and the flow depends on the speed and direction of the pump assembly <NUM> as well as the state of the valves 250a-m.

Fluid line connectors 208a-g are positioned along the bottom edge of the PD cassette <NUM>. As noted above, the fluid channels <NUM> in the PD cassette <NUM> lead from the pump assembly <NUM> to the connectors 208a-g. The PD cassette <NUM> is configured to move the dialysis solution between the fill bag <NUM> and one or more of the storage bags <NUM>. The connectors 208a-g are configured to receive fittings of storage bag lines <NUM>, the fill bag line <NUM>, the patient line <NUM>, and the drain line <NUM>. In particular, storage bag lines <NUM> are connected to the connectors 208a-d, the fill bag line <NUM> is connected to the connector 208e, the patient line <NUM> is connected to the connector 208f, and the drain line <NUM> is connected to the connector <NUM>. Flow through each of the connectors 208a-g is controlled by a corresponding valve 250a-g. The PD cassette <NUM> also includes a plurality of valves <NUM>-m disposed in the plurality of channels <NUM> disposed therein.

With reference to <FIG>, the pump assembly <NUM> includes the pump housing <NUM>, which is formed from the first and second pump housing portions <NUM> and <NUM>. The pump housing <NUM> is fluidly sealed by coupling the pump housing portions <NUM> and <NUM> using adhesive, welding, or using any other suitable methods. In embodiments, the pump housing <NUM> may be formed as a single component unit via molding. The pump housing <NUM> also includes a first connection <NUM> (e.g., inlet) and a second connection <NUM> (e.g., outlet) formed by the first and second pump housing portions <NUM> and <NUM>. The pump assembly <NUM> may be operated in unidirectional or bidirectional manner such that the first connection <NUM> is the outlet and the second connection <NUM> is the inlet. Each of the first and second connections <NUM> and <NUM> are coupled to the fluid channels <NUM> to allow for movement of fluid therethrough by the pump assembly <NUM>.

The pump assembly <NUM> also includes a flexible rotor <NUM>. With reference to <FIG>, the flexible rotor <NUM> includes a central shaft <NUM> with a plurality of vanes <NUM> extending radially from the shaft <NUM>. Each of the vanes <NUM> terminates in a projection <NUM>, which may have a cylindrical shape whose longitudinal axis is perpendicular to a radial axis defined by each of the vanes <NUM>. The flexible rotor <NUM> may have any number of vanes <NUM>, which for example may be from <NUM> to <NUM>. The distance between the vanes <NUM>, i.e., a straight line between neighboring projections <NUM>, may be equal to the width or diameter of each of the first and second connections <NUM> and <NUM>.

The vanes <NUM> have substantially the same width as the inner width of the pump housing <NUM>, such that the vanes <NUM> contact the inner portion of the pump housing <NUM>. The flexible rotor <NUM> may be formed from any suitable flexible polymeric material and may be formed by co-molding an elastomer, such as silicone rubber, and a thermoplastic polymer, including, but not limited to, polyoxymethylenes, polyurethanes, polycarbonate resins, polyamides, polyphenylene sulfides, acrylonitrile butadiene styrene resins, polyether ether ketones, polyphenylene oxides, polypropylenes, and combinations thereof.

With reference to <FIG>, the pump housing <NUM> has a substantially circular planar cross-section. The pump housing <NUM> also includes a radial narrowing portion <NUM>, which reduces the radius of the pump housing <NUM>. The flexible rotor <NUM> is rotated about a rotation axis that is perpendicular to a plane defined by the cassette housing <NUM>, i.e., the plane between the inner portion <NUM> and the outer portion <NUM>. As used herein, the terms "parallel" and "perpendicular" include relative configurations that are substantially parallel and substantially perpendicular up to about + or - <NUM> degrees from true parallel and true perpendicular. As the flexible rotor <NUM> is rotated within the pump housing <NUM>, the vanes <NUM> are compressed as shown in <FIG>. The narrowing portion <NUM> is disposed between the first and second connections <NUM> and <NUM> and may be arcuately-shaped with a larger radius than the radius of the pump housing <NUM> with the center of the narrowing portion <NUM> being offset from the center of the pump housing <NUM>.

The second pump housing portion <NUM> defines an opening <NUM> for coupling the rotor <NUM> to the cassette interface <NUM>. With reference to <FIG>, the pump assembly <NUM> includes a drive shaft <NUM> configured to couple to and be rotatable by a motor (not shown). The drive shaft <NUM> includes a plurality of fins <NUM> configured to engage a corresponding opening <NUM> within the central shaft <NUM> of the flexible rotor <NUM>. The drive shaft <NUM> is inserted through the opening <NUM>. A gasket <NUM> covers the opening <NUM> and forms a fluid-tight seal between the flexible rotor <NUM> and the drive shaft <NUM> passing through an opening in the gasket <NUM>. The gasket <NUM> may be formed from a polymeric flexible material, which may be formed by co-molding an elastomer, such as silicone rubber, and a thermoplastic polymer, such as, polyester, polyethylene terephthalate glycol, high-density polyethylene, and combinations thereof.

With reference to <FIG> and <FIG>, one of the valves 250a-m is shown as a valve <NUM>, which may be a pinch valve formed from the membrane <NUM> that is compressed by an actuator <NUM>. The valve <NUM> is disposed within the fluid channel <NUM> and a bottom surface of the valve <NUM> abuts the flexible membrane <NUM>. The actuator <NUM> includes a tip <NUM> formed from a conformable material and is shaped to fit within the channel <NUM>. The actuator <NUM> is disposed within the cassette interface <NUM> and is movable along a longitudinal axis that is transverse to a plane defined by the PD cassette <NUM>, thereby pushing the membrane <NUM> into the channel <NUM> blocking the channel <NUM>. The actuator <NUM> may be a spring-loaded pneumatic or solenoid actuator. With reference to <FIG> and <FIG>, the valve <NUM> is shown in an open configuration, in which the actuator <NUM> is withdrawn and may contact the membrane <NUM> without impinging on the membrane <NUM>, keeping the channel <NUM> open. As shown in <FIG> and <FIG>, the valve <NUM> is shown in a closed configuration, in which the actuator <NUM> is advanced longitudinally and compresses the membrane <NUM> into the channel <NUM>, thereby blocking the channel <NUM>. Thus, the flow of dialysis solution through the PD cassette <NUM> is controlled using selective depression of the portions of the membrane <NUM> by selectively activating the actuators <NUM> and rotating the rotor <NUM> in either direction, i.e., clockwise or counterclockwise, at a selected rate of rotation.

With reference to <FIG>, the PD cassette <NUM> is in a filling configuration, in which the fill bag <NUM> is filled with the dialysis solution from one or more of the storage bags <NUM>. The flow of the dialysis solution is shown by an arrow <NUM>. The valves 250a-e are open, with the valves 250a-d opening the connectors 208a-d to the storage bags <NUM> and the valve 250e opening the connector 208e to the fill bag <NUM>. In addition, valves <NUM>, j, k, and m are also open, with the remaining valves being closed, and the pump assembly <NUM> is operated in the first direction, which transfers the fluid from the storage bags <NUM> to the fill bag <NUM>.

With reference to <FIG>, the PD cassette <NUM> is in a first priming configuration for priming a first portion of the channels <NUM> from the fill bag <NUM>. The flow of the dialysis solution is shown by an arrow <NUM>. The valves 250e, g, i, and <NUM> are open and the pump assembly <NUM> is operated in a first direction such that dialysis solution from the fill bag line <NUM> connected to the connector 208e flows to the connector <NUM> and to the drain line <NUM>. In this configuration, the fluid channels <NUM> interconnecting the connectors 208e and <NUM> are primed.

With reference to <FIG>, the PD cassette <NUM> is in a second priming configuration for priming a second portion the channels <NUM> from the fill bag <NUM>. The flow of the dialysis solution is shown by an arrow <NUM>. The valves 250e, i, g, and m are open, with the remaining valves being closed, and the pump assembly <NUM> is operated in a first direction such that dialysis solution from the fill bag line <NUM> connected to the connector 208e flows to the connector <NUM> and to the drain line <NUM>. In this configuration, the fluid channel <NUM> interconnecting the connectors 208e and <NUM> are primed.

With reference to <FIG>, the PD cassette <NUM> is shown in a patient filling configuration, in which the valves 250e, f, i, m, and k are open, with the remaining valves being closed, and the pump assembly <NUM> is operated in the first direction to move the fluid to the patient line <NUM>. The flow of the dialysis solution is shown by an arrow <NUM>. In this configuration, the dialysis solution from the fill bag line <NUM> connected to the connector 208e flows to the connector 208f and to the patient line <NUM> to allow for the dialysis solution to be infused into the patient.

<FIG> shows the PD cassette <NUM> in a drain configuration, in which the dialysis solution is removed from the patient after the infusion is completed and the dialysis solution has dwelled in the patient for the duration of the treatment time. The valves 250f, g, i, j, and m, are open. The flow of the dialysis solution is shown by an arrow <NUM>. The pump assembly <NUM> is operated in the first direction such that the dialysis solution is drained from the patient. In this configuration, the fluid is withdrawn from the patient through the patient line <NUM> connected to the connector 208f and to the connector <NUM> coupled to the drain line <NUM>.

Claim 1:
A dialysis system (<NUM>) comprising:
a peritoneal dialysis cycler (<NUM>) including:
a cassette interface (<NUM>);
a patient line (<NUM>);
a drain line (<NUM>);
a plurality of fluid storage bag lines (<NUM>);
a fill bag line (<NUM>);
and
a cassette (<NUM>) coupled to the cassette interface (<NUM>), the patient line (<NUM>),
the drain line (<NUM>), the fluid storage bag lines (<NUM>) and the fill bag line (<NUM>), the cassette including:
a cassette housing;
a plurality of channels (<NUM>) fluidly coupled to a plurality of connectors (208a-g) each of which is coupled to a respective one of the patient line (<NUM>), the drain line (<NUM>), the fluid storage bag lines (<NUM>) and the fill bag line (<NUM>);
a plurality of valves (250a-m) disposed within the plurality of channels (<NUM>); and
a single pump assembly (<NUM>) disposed within the cassette housing, the pump assembly having:
a pump housing (<NUM>), wherein the pump housing includes an inlet (<NUM>) and an outlet (<NUM>) coupled to the plurality of channels (<NUM>); and
characterized in that the pump assembly comprises a flexible rotor (<NUM>) including a plurality of flexible vanes (<NUM>), wherein the flexible rotor is rotatable in either a clockwise direction or a counterclockwise direction to move a fluid through the plurality of channels (<NUM>).