Patent Description:
People with damaged or improperly functioning kidneys may undergo dialysis treatments to remove waste products from blood. One common type of dialysis is peritoneal dialysis ("PD"), in which a cleansing fluid, referred to as PD or dialysis fluid, is delivered to a patient's peritoneal cavity of their abdomen via a catheter. The cleansing fluid absorbs waste products during a dwell period. After the dwell period ends, the cleansing fluid is removed from the patient's peritoneal cavity along with the absorbed waste products and excess water (known as ultrafiltration), thereby compensating for the patient's improperly functioning kidneys.

An automated peritoneal dialysis ("APD") machine is used in many instances to pump a prescribed volume of a PD or dialysis fluid (e.g., a cleansing fluid) into a patient's peritoneal cavity. The APD machine is configured to permit the dialysis fluid to remain in the patient during the dwell period. After the dwell period, the APD machine drains used dialysis fluid or effluent containing waste products from the patient's peritoneal cavity. APD machines typically prime tubes and/or a tubing set that routes the dialysis fluid to the patient. The priming of the tubes and/or tubing set removes air, thereby preventing the air from being transmitted into the patient's peritoneal cavity. Priming may involve pumping the dialysis fluid to an end of a tube, such as a patient line that is later connected to the patient during the PD treatment, to remove the air within the tube.

APD machines are typically located in a patient's home, a clinic, or a hospital. In many instances, a patient prepares the APD machine for treatment by performing a priming sequence. To aid in priming the tubes, APD machines may include a sensor that detects when a tube is properly primed. Known sensors have used light to detect when the dialysis fluid has reached the end of a tube, which is indicative of a successful prime. However, fluctuations in ambient light, tube properties, tube geometries, and/or fluid type may cause the light sensor to be less accurate than desired.

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

A peritoneal dialysis apparatus according to the present invention comprises the technical features as defined in independent claim <NUM>. A priming sensor apparatus according to the present invention comprises the technical features as defined in independent claim <NUM>.

The example system, apparatus, and method disclosed herein are configured to provide an accurate medical fluid treatment priming sensor that is insensitive to ambient light brightness, tube properties, and/or fluid type. The dialysis priming sensor disclosed herein uses capacitance sensing. The priming sensor includes a housing that encloses electrodes and/or conductive plates that are connected to one or more sensors that measure a capacitance between the electrodes and/or conductive plates. The electrodes and/or conductive plates are positioned within the housing to form one or more capacitors. The electrodes and/or conductive plates may be located on opposite sides of the housing for detecting a fluid level based on a capacitance change when a medical fluid (e.g., dialysis fluid, dialysate, tap water, or other conductive fluids) flows through the inserted tube past the electrodes and/or conductive plates. Additionally or alternatively, at least some of the electrodes and/or conductive plates may be placed at different heights with respect to a patient tube placed in the priming sensor. The positioning of the electrodes and/or conductive plates at different heights aids in the detection of the patient tube. Placement of the patient tube in the housing of the priming sensor causes at least one electrode and/or conductive plate to move relative to other stationary electrode(s) and/or conductive plate(s) that are placed at different heights, thereby causing a change in capacitance for detecting the presence of the tube. In some embodiments, the positioning of the electrodes and/or conductive plates at different heights provides for additionally or alternatively detecting a fluid level in the patient tube.

A processor (or a control unit having one or more processors and one or more memories) analyzes the output from the one or more capacitive sensors to determine whether a patient tube is present and inserted within the priming sensor housing (e.g., detecting between a no-tube state and a dry tube state). The processor or the control unit is also configured to determine when a medical fluid such as dialysis fluid reaches a certain level in the patient tube corresponding to a successful prime (e.g., detecting between a dry state and a wet state). After detecting that a tube is present and includes a fluid (e.g., a wet tube state), the processor or the control unit is further configured to provide an indication that priming of a patient line for PD therapy is successful, which permits the priming sequence to continue/end a PD treatment to begin. In some instances, the processor or the control unit may also provide an indication that the dry tube state is not present. The processor or the control unit may also be configured to provide an indication of a failed prime of the patient line if, for example, the tube itself is not detected or the wet tube state of the tube is not detected within a defined period of time.

According to a first aspect of the present invention, there is provided a peritoneal dialysis apparatus including a patient tube configured to receive dialysis fluid from a source of dialysis fluid, at least one pump configured to move dialysis fluid from the source to the patient tube during a priming sequence, and a priming sensor including a housing having a recessed section configured to accept a portion of the patient tube. The recessed section of the housing includes a first side including a first conductive plate, and a member including a second conductive plate. The member is moveably connected to a second side of the recessed section and configured for a desired movement upon insertion of the portion of the patient tube into the housing of the priming sensor. The recessed section also includes a third side opposing the first side. The third side includes a third conductive plate disposed across from a top portion of the first conductive plate, and a fourth conductive plate disposed across from a bottom portion of the first conductive plate. The peritoneal dialysis apparatus also includes a first capacitive sensor positioned and arranged to measure a first capacitance between the first conductive plate and the third conductive plate, a second capacitive sensor positioned and arranged to measure a second capacitance between the third conductive plate and the fourth conductive plate, and a processor configured to operate with the at least one pump, the first capacitive sensor, and the second capacitive sensor. The processor is configured to use the measured second capacitance to determine a first transition between (i) a no-tube state and (ii) a dry tube state based on a distance of the second conductive plate from the third and fourth conductive plates, use the measured first capacitance to determine a second transition between (ii) the dry tube state and (iii) a wet tube state based on a presence of fluid within the patient tube, cause the at least one pump to pump the fluid through to the patient tube for the priming sequence after the dry tube state is determined, and transmit a message indicative that the patient tube is primed after the wet tube state is determined.

In a first embodiment of the peritoneal dialysis apparatus of the first aspect of the present invention, the priming sensor includes a third capacitive sensor positioned and arranged to measure a third capacitance between the first conductive plate and the fourth conductive plate, and wherein the processor is configured to combine values of the first capacitance with value of the third capacitance to determine between at least one of (i) the no-tube state and (ii) the dry tube state, or (ii) the dry tube state and (iii) the wet tube state.

In a second embodiment of the peritoneal dialysis apparatus of the first aspect of the present invention, which may also be used in combination with the first embodiment, the second conductive plate bends or pivots when the portion of the patient tube is inserted into the housing of the priming sensor, causing the first capacitance to increase.

In a third embodiment of the peritoneal dialysis apparatus of the first aspect of the present invention, which may also be used in combination with the first and/or second embodiment, the second conductive plate is at least one of (a) positioned and arranged to electrically float, or (b) formed from a conductive plastic or a conductively painted plastic.

In a fourth embodiment of the peritoneal dialysis apparatus of the first aspect of the present invention, which may also be used in combination with any one of the first to third embodiments, the third conductive plate is at least one of (a) formed with a width that is equal to a width of the fourth conductive plate, or (b) spaced apart from the fourth conductive plate by a distance between <NUM> millimeters and <NUM> centimeters.

In a fifth embodiment of the peritoneal dialysis apparatus of the first aspect of the present invention, which may also be used in combination with any one of the first to fourth embodiments, the first conductive plate, the third conductive plate, and the fourth conductive plate are at least one of (a) formed as metal clips configured to secure the portion of the patient tube within the housing of the priming sensor, or (b) enclosed within the recessed section of the housing of the priming sensor.

In a sixth embodiment of the peritoneal dialysis apparatus of the first aspect of the present invention, which may also be used in combination with any one of the first to fifth embodiments, the processor is configured to determine the first transition between the no-tube state and the dry tube state by determining that a change in values of the measured first capacitance is greater than a first transition threshold, and the processor is configured to determine the second transition between the dry tube state and the wet tube state by determining that a change in values of the measured second capacitance is greater than a second transition threshold.

In a seventh embodiment of the peritoneal dialysis apparatus of the first aspect of the present invention, which may also be used in combination with any one of the first to sixth embodiments, at least one of the first transition threshold and the second transition threshold corresponds to at least a doubling of the respective values of the measured capacitance from a first value to a second value in less than <NUM> seconds, and wherein the second value is at least substantially constant for at least two seconds.

In an eighth embodiment of the peritoneal dialysis apparatus of the first aspect of the present invention, which may also be used in combination with any one of the first to seventh embodiments, the priming sensor includes fifth and sixth conductive plates located on opposing exterior sides of the housing, and third and fourth capacitive sensors positioned and arranged to measure capacitances that change due to an external interference that is detected by at least one of the fifth or sixth conductive plates positioned relative to the first conductive plate, the third conductive plate, and the fourth conductive plate.

In a ninth embodiment of the peritoneal dialysis apparatus of the first aspect of the present invention, which may also be used in combination with any one of the first to eighth embodiments, after detecting a change in the capacitance measured by the third and fourth capacitive sensors, the processor is configured to, at least one of refrain from detecting the states (i) to (iii), stop the priming sequence, or output a message that is indicative of the detected capacitance interference.

In a tenth embodiment of the peritoneal dialysis apparatus of the first aspect of the present invention, which may also be used in combination with any one of the first to ninth embodiments, the processor is further configured such that if the wet tube state is determined, a peritoneal dialysis treatment is enabled.

In an eleventh embodiment of the peritoneal dialysis apparatus of the first aspect of the present invention, which may also be used in combination with any one of the first to tenth embodiments, the peritoneal dialysis apparatus includes a user interface configured to display at least one of text or a graphic corresponding to the determined state (i) to (iii).

According to a second aspect of the present invention, there is provided a priming sensor apparatus comprising a housing including a recessed section configured to accept a portion of a patient tube. The housing includes a first side including a first conductive plate, and a member including a second conductive plate. The member is moveably connected to a second side of the recessed section for detecting insertion of the portion of the patient tube into the housing. The recessed section also includes a third side opposing the first side. The third side includes a third conductive plate disposed across from a top portion of the first conductive plate, and a fourth conductive plate disposed across from a bottom portion of the first conductive plate. The sensor apparatus also includes a first capacitive sensor positioned and arranged to measure a first capacitance between the first conductive plate and the third conductive plate, and a second capacitive sensor positioned and arranged to measure a second capacitance between the third conductive plate and the fourth conductive plate.

In a first embodiment of the sensor apparatus of the second aspect of the present invention, the sensor apparatus is operable with a medical fluid delivery machine including at least one pump and a control unit operable with the first and second capacitive sensors to use the measured second capacitance to determine a first transition between (i) a no-tube state and (ii) a dry tube state based on a distance of the second conductive plate from the third and fourth conductive plates, and cause the at least one pump to pump the fluid through to the tube to conduct a priming sequence after the dry tube state is determined.

In a second embodiment of the sensor apparatus of the second aspect of the present invention, which may also be used in combination with the first embodiment, the control unit is further configured to use the measured first capacitance to determine a second transition between (ii) the dry tube state and (iii) a wet tube state based on a presence of fluid within the tube, and transmit a message indicative that the tube is primed after the wet tube state is determined.

In a third embodiment of the sensor apparatus of the second aspect of the present invention, which may also be used in combination with the first and/or second embodiment, the control unit is further configured to increment a counter each time the wet tube state is determined, compare a value of the counter to a counter threshold, and determine the wet tube state when the value of the counter equals or exceeds the counter threshold.

In a fourth embodiment of the sensor apparatus of the second aspect of the present invention, which may also be used in combination with any one of the first to third embodiments, the control unit includes the first capacitive sensor and the second capacitive sensor.

In light of the present disclosure and the above aspects, it is therefore an advantage of the present disclosure to provide an improved priming system, device, and method for a medical fluid delivery system, such as an automatic peritoneal dialysis ("APD") system.

It is another advantage of the present disclosure to accurately detect when (i) a tube is present and (ii) a fluid reaches a certain position within the tube regardless of ambient light, tube properties, and/or fluid properties.

It is yet another advantage of the present disclosure to provide a priming sensor and methodology that may be applied to different types of medical fluid delivery machines.

The advantages discussed herein may be found in one, or some, and perhaps not all of the embodiments disclosed herein. Additional features and advantages are described herein, and will be apparent from, the following Detailed Description and the figures.

A medical fluid delivery system is disclosed herein. The example medical fluid delivery system may include an automated peritoneal dialysis ("APD") machine, a hemodialysis machine, a medical fluid delivery machine, or any other machine requiring one or more lines to be primed. The medical fluid delivery system includes a priming sensor configured to detect when at least one tube or line set is present and when the tube is fully primed with an appropriate fluid, such as fresh dialysis fluid. The priming sensor includes one or more capacitive sensors. During a priming operation, the capacitive sensors perform capacitance measurements between two or more electrodes or conductive plates. Capacitance measurement values from the one or more capacitive sensors may be compared to one or more thresholds. The comparison is used to determine different possible states of a patient tube including, for example, a no-tube state, a dry tube state, and a wet tube state.

In some examples, the medical fluid delivery system is configured such that if a no-tube state is detected, the medical fluid delivery system provides an alert indicative that a patient tube needs to be inserted into the priming sensor. The medical fluid delivery system may prevent the priming of the patient tube until the tube is detected by the priming sensor. If a dry tube state is detected, the medical fluid delivery system may begin and/or continue a priming sequence by pumping a fluid from a fluid source into the patient tube. If a wet tube state is detected, the medical fluid delivery system may stop the pumping of the priming fluid and/or end the priming sequence. In some embodiments, the medical fluid delivery system may be configured to confirm the wet tube state by detecting the wet tube state multiple times (e.g., between two and ten times in rapid succession to validate the wet tube state) before priming ends.

In some embodiments, the priming sensor disclosed herein includes a housing having a recessed section configured to accept and/or hold a patient tube or line set. At least some of the electrodes and/or conductive plates are located on opposite sides of the recessed section. As such, the electrodes and/or conductive plates are located on opposite sides of a patient tube when the tube is inserted into the priming sensor. Placement of the tube in the priming sensor causes a capacitance to change between the electrodes. In some embodiments, an electrode and/or conductive plate may be placed on a retaining clip that is located within the recessed section. Placement of the patient tube within the priming sensor causes the retaining clip to move toward at least one stationary electrode or conductive plate located in the recessed section of the housing. The movement of the clip caused by the insertion of the patient tube causes a change in capacitance, thereby providing for detection of the patient tube in the priming sensor.

Additionally, at least some of the electrodes and/or conductive plates are located at different heights of the housing of the priming sensor. The electrodes and/or conductive plates are separated by at least one gap. The positioning of the electrodes and/or conductive plates at different heights enables a fluid level to be determined based on a capacitance change when a dialysis fluid flows through the inserted tube and past the electrodes and/or conductive plates. The capacitance increases when the dialysis fluid flows between the electrodes and/or conductive plates because an effective distance between the electrodes or plates is reduced when a fluid replaces air between the electrodes or plates.

The example system, method, and apparatus disclosed herein provide an improvement over known priming sensors that detect a tube state using light. Known light-based priming sensors activate all of the light emitters individually. The emitters are activated to have the same brightness level. The detected light from each emitter is compared to a separate threshold (or combined into a ratio and compared to a threshold), where a tube state is determined based on a weighted average of the threshold comparisons. Increases in ambient light decrease the sensor's ability to discern brightness levels corresponding to the different tube states.

In contrast to known sensors, the example system, method, and apparatus disclosed herein, uses capacitive sensing to detect tube state. Capacitive sensing is not affected by ambient light, environmental contamination, bubbles in a priming fluid, tube thickness, or tube clarity/transparency. As a result, the capacitive sensing used by the priming sensor disclosed herein is not prone to false state detection due to these common problems. Additionally, capacitance detection for each of the states has a relatively high signal to noise ratio, e.g., greater than <NUM>: <NUM>. The example capacitive sensors disclosed herein may seal or otherwise enclose their electrodes, conductive plates, and other electronics within a sensor housing, thereby preventing fluid ingress and the issues that arise if the dialysis fluid contacts the electronics. Capacitive sensors also have fewer parts with fewer tolerance requirements compared to light-based sensors, and may therefore be less expensive to manufacture.

In some embodiments, the priming sensor may be configured to detect electrical interference from, for example, an operator. Generally, since humans affect electric fields, placement of an operator's hand near the priming sensor may cause measured capacitance to change. Similarly, placement of a user device, such as a smartphone near the priming sensor may cause the electric field to change, thereby changing the capacitance measurement. In some embodiments, a processor or control unit for the priming sensor is configured to detect significant variations in capacitance measurements. The processor or control unit may be configured to detect spikes and sharp drops in capacitance over relatively short periods of time, such as less than one or two seconds, which are indicative of the presence of a hand or electronic device. In response to such a detection, the processor or the control unit may refrain from concluding that a tube state change has occurred until the electrical interference is removed. In some instances, the processor or the control unit may also provide an error message on a display screen of the medical device indicating the detected interference and possibly provide an instruction to remove or eliminate the interference.

Additionally or alternatively, the priming sensor may be configured to prevent the external electrical interference. For instance, a housing of the priming sensor may include shielding, such as metallic plates, carbon filled conductive plastic, metal plated plastic, plastic sprayed with conductive paint, etc. The shielding prevents electrical interference from reaching the capacitive electrodes or conductive plates. In other instances, the priming sensor may include an additional capacitive electrode or conductive plate that is positioned adjacent to an external side of the housing of the priming sensor. The additional capacitive electrode or conductive plate is configured to detect a change in electrical field external to the priming sensor. The processor or the control unit for the priming sensor may, for example, subtract the detected change in capacitance due to the external source from the capacitance change detected within the recessed section for determining a tube state.

The example disclosure refers to peritoneal dialysis and priming a patient tube. It should be appreciated that the example system, apparatus, and method disclosed herein can be provided to operate with any type of dialysis machine, including a hemodialysis machine or a continuous replacement treatment machine. Moreover, the improved priming sensing discussed herein is not limited to dialysis, and may be used with any type of medical fluid machine, such as a medical delivery machine (e.g., an infusion pump). Further, while the disclosure relates to a patient tube, in other examples, other tubes may be primed using a priming sensor of the present disclosure, such as a heating tube, a drain tube, a medical fluid source tube, etc. Further, while the disclosure references priming a tube using dialysis fluid, it should be appreciated that the example system, apparatus, and method may operate with any type of medical fluid, including an intravenous drug, saline, renal therapy fluid, blood, sterile water, etc. Additionally, the improved sensing may be used for any purpose in which it is desired to know whether a tube is present or not and if so, whether the tube contains a liquid.

Further, while the disclosure refers to capacitive sensors, it should be appreciated that other sensors could be used. For example, the capacitive sensing disclosed herein could be replaced with inductive sensors. Moreover, the capacitive sensors may be replaced and/or used in conjunction with pressure sensors, radio-frequency ("RF") sensors, proximity detection sensors, etc..

Referring now to the drawings, <FIG> illustrates an example medical fluid delivery system <NUM>, according to an example embodiment of the present disclosure. The medical fluid delivery system <NUM> in the illustrated embodiment includes a dialysis machine <NUM> configured to provide renal failure therapy to one or more patients. Renal failure therapy helps a patient balance water and minerals. Renal failure therapy also helps excrete daily metabolic load by removing a patient's toxic end products of nitrogen metabolism (urea, creatinine, uric acid, and others), which accumulate in blood and tissue. Renal failure therapy for the replacement of kidney function is critical to many people because the treatment is life saving.

In some examples, the dialysis machine <NUM> is an APD machine. The example dialysis machine <NUM> is configured to deliver dialysis fluid into a patient's peritoneal cavity via a catheter. The dialysis fluid contacts the peritoneal membrane of the peritoneal cavity for a period of time, which is referred to as a dwell period. Waste, toxins and excess water pass from the patient's bloodstream, through the peritoneal membrane and into the dialysis fluid due to diffusion and osmosis, i.e., an osmotic gradient occurs across the membrane. An osmotic agent in dialysis provides the osmotic gradient. The used or spent dialysis fluid is drained from the patient, removing waste, toxins and excess water from the patient. This cycle is repeated, e.g., multiple times.

There are various types of peritoneal dialysis therapies, including continuous ambulatory peritoneal dialysis ("CAPD"), automated peritoneal dialysis ("APD"), and tidal flow dialysis and continuous flow peritoneal dialysis ("CFPD"). CAPD is a manual dialysis treatment. Here, the patient manually connects an implanted catheter to a drain to allow used or spent dialysis fluid to drain from the peritoneal cavity. The patient then connects the catheter to a bag of fresh dialysis fluid to infuse fresh dialysis fluid through the catheter and into the patient. The patient disconnects the catheter from the fresh dialysis fluid bag and allows the dialysis fluid to dwell within the peritoneal cavity, wherein the transfer of waste, toxins and excess water takes place. After a dwell period, the patient repeats the manual dialysis procedure, for example, four times per day, each treatment lasting about an hour. Manual peritoneal dialysis requires a significant amount of time and effort from the patient, leaving ample room for improvement.

Automated peritoneal dialysis ("APD") is similar to CAPD in that the dialysis treatment includes drain, fill and dwell cycles. APD machines, such as the dialysis machine <NUM>, however, perform the cycles automatically, typically while the patient sleeps. APD machines free patients from having to perform the treatment cycles manually and from having to transport supplies during the day. APD machines connect fluidly to an implanted catheter, to a source or bag of fresh dialysis fluid and to a fluid drain. APD machines pump fresh dialysis fluid from a dialysis fluid source, through the catheter and into the patient's peritoneal cavity. APD machines also allow for the dialysis fluid to dwell within the cavity and for the transfer of waste, toxins and excess water to take place. The source may include multiple sterile dialysis fluid bags.

APD machines pump used or spent dialysis fluid from the peritoneal cavity, though the catheter, and to the drain. As with the manual process, several drain, fill and dwell cycles occur during dialysis. A "last fill" occurs at the end of APD and remains in the peritoneal cavity of the patient until the next treatment.

In some embodiments, the dialysis machine <NUM> may be configured to perform hemodialysis ("HD"). During HD, the dialysis machine <NUM> is configured to use diffusion to remove waste products from a patient's blood. A diffusive gradient occurs across the semipermeable dialyzer between a patient's blood and an electrolyte solution called dialysate or dialysis fluid to cause diffusion. HF is accomplished by adding substitution or replacement fluid to the extracorporeal circuit during treatment (typically ten to ninety liters of such fluid). The substitution fluid and the fluid accumulated by the patient in between treatments is ultrafiltered over the course of the HF treatment, providing a convective transport mechanism that is particularly beneficial in removing middle and large molecules (in hemodialysis there is a small amount of waste removed along with the fluid gained between dialysis sessions, however, the solute drag from the removal of that ultrafiltrate is not enough to provide convective clearance).

The example dialysis machine <NUM> may be located in a center, a hospital, or a patient's home. A trend towards home dialysis exists today in part because home dialysis can be performed daily, offering therapeutic benefits over in-center dialysis treatments, which occur typically bi- or tri-weekly. Studies have shown that frequent treatments remove more toxins and waste products than a patient receiving less frequent but perhaps longer treatments. A patient receiving treatments more frequently does not experience as much of a down cycle as does an in-center patient, who has built-up two or three days' worth of toxins prior to treatment. In certain areas, the closest dialysis center can be many miles from the patient's home causing door-to-door treatment time to consume a large portion of the day. Home dialysis may take place overnight or during the day while the patient relaxes, works or is otherwise productive. Much of the appeal of a home treatment for the patient revolves around the lifestyle flexibility provided by allowing the patient to perform treatment in his or her home largely according to his or her own schedule.

Any of the above dialysis modalities performed by the dialysis machine <NUM> may be run on a scheduled basis and may require a start-up procedure. For example, dialysis patients typically perform treatment on a scheduled basis, such as every other day, daily, etc. Dialysis treatment machines typically require a certain amount of time before treatment for setup, for example, to run a priming and/or disinfection procedure. During a priming procedure, a fluid is pumped through one or more dialysis tubes/lines and/or cassettes to remove air and/or in-line particulates. Priming dialysis tubes/lines and/or cassettes prevents air and/or the particulates from coming into contact with the patient.

The example dialysis machine <NUM> of <FIG> includes a priming sensor <NUM> configured to detect appropriate priming of at least one dialysis tube/line. In the illustrated embodiment, the priming sensor <NUM> is configured to detect priming of a patient tube <NUM>. In other embodiments, the priming sensor <NUM> is configured for priming of additional or alternative tubes, such as to-patient tubes/from-patient tubes of a continuous flow peritoneal dialysis set, drain tubes, heating tubes, source fluid tubes, concentrate tubes, etc. For HD, the priming sensor <NUM> may be configured to prime an extracorporeal circuit, a to-dialyzer tube, a from-dialyzer tube, a source tube, a blood tube, a saline tube, and/or a drain tube. The patient tube <NUM> may be made of any suitable medical grade material, such as polyvinyl chloride ("PVC"), silicone, or other non-PVC material. The tube <NUM> in one embodiment has an inner or outer diameter that is equal to or less than <NUM> millimeters or <NUM> millimeters.

The dialysis machine <NUM> in the illustrated embodiment includes at least one pump <NUM> configured to move dialysis fluid from a fluid source <NUM> to the patient tube <NUM>. The pump <NUM> may include any type of pump, including a peristaltic pump, a rotary pump, a gear pump, a platen, a linear actuator pump, a diaphragm pump, etc. The pump <NUM> is operated to prime the patient tube <NUM> with dialysis fluid. The pump <NUM> is also operated to provide dialysis fluid from the fluid source <NUM> to a patient when the patient tube <NUM> is connected to a catheter that is inserted into a patient's peritoneal cavity. Priming may alternatively or additionally be performed using gravity where, for example, a source of fluid is provided at a head height above the dialysis machine <NUM>.

In some embodiments, the dialysis machine <NUM> includes a disposable cassette, which is connected fluidly to the patient tube <NUM> and other tubing such as fill tubes and drain tubes. The cassette may include one or more flexible membranes and associated chambers that operate with valves and/or pumps in the dialysis machine <NUM>. Priming the patient tube <NUM> may include priming the disposable cassette with the dialysis fluid in addition to the one or more connected tubes.

The fluid source <NUM> may include one or more containers of pre-mixed dialysis fluid. In some embodiments, the fluid source <NUM> may include containers or reservoirs of concentrate that have been mixed with pure water to form dialysis fluid. Additionally or alternatively, the fluid source <NUM> may include an on-line source, such as a source of purified water that is mixed with one or more concentrates to form dialysis fluid. Moreover, in some examples, the fluid source <NUM> may include a fluid preparation device that provides prepared dialysis fluid to the dialysis machine <NUM> via one or more fluid connections.

The example dialysis machine <NUM> of <FIG> also includes one or more processors <NUM> and one or more memories <NUM> that form a control unit <NUM>. The processor(s) <NUM> may include any type of device capable of processing inputs and performing one or more calculations to determine one or more outputs. The processor(s) <NUM> may include a microcontroller, a microprocessor unit ("MPU"), a controller, an application specific integrated circuit ("ASIC"), a central processing unit included on one or more integrated circuits, etc. In some embodiments, the processor(s) <NUM> may include a first processing device that is configured to process measured capacitances and determine a tube state and a second processing device that is configured to perform dialysis operations using, in part, data and instructions from the first processing device that are indicative of the tube state.

The memory <NUM> may include any volatile or non-volatile data/instruction storage device. The memory <NUM> may include, for example, flash memory, random-access memory ("RAM"), read-only memory ("ROM"), Electrically Erasable Programmable Read-Only Memory ("EEPROM"), etc. The example memory <NUM> is configured to store one or more instructions executable by the processor <NUM> to cause the processor <NUM> to perform operations disclosed herein. The instructions may be part of one or more software programs or applications. References herein to the processor <NUM> being configured to perform an operation may include embodiments in which the memory <NUM> stores instructions that are configured to cause the processor <NUM> to perform the described operation. The processor <NUM> and the memory are collectively referred to as a control unit <NUM>.

The example memory <NUM> is configured to store instructions that cause the processor(s) <NUM> to detect a tube state and/or operate the dialysis machine <NUM>. The processor <NUM> (or a second processor of the dialysis machine <NUM>) may also provide control signals or instructions to the pump <NUM> and/or cause the pump <NUM> to move dialysis fluid from the fluid source <NUM> to the patient tube <NUM> during a priming sequence and during a dialysis treatment. The operations performed by the processor(s) <NUM>, when called upon to do so, also include periodically (e.g., every <NUM> millisecond ("ms"), <NUM>, <NUM>, <NUM>, <NUM>, <NUM> second, <NUM> seconds, etc.) and/or continually measuring a capacitance between electrodes and/or conductive plates of the priming sensor <NUM>. As disclosed herein, the memory <NUM> includes instructions that cause the processor <NUM> to analyze values indicative of measured capacitance of the priming sensor <NUM> to determine a state of the patient tube <NUM>.

The example processor <NUM> is also configured to transmit one or more messages to a user interface <NUM> of the dialysis machine <NUM> for displaying or otherwise conveying information on a display screen, such as a touchscreen. The processor <NUM> may cause the user interface <NUM> to display instructions to a patient for preparing the dialysis machine <NUM> for a treatment, including actions to prepare for a priming sequence. The user interface <NUM> may also display or otherwise convey indications that are indicative of alert conditions, such as a warning to place the patient tube <NUM> within the priming sensor <NUM> or to connect the patient tube <NUM> to a catheter after a priming sequence has been completed. The user interface <NUM> may include a touchscreen overlay and/or electromechanical actuators, buttons, and/or switches to enable an operator to input information. An input received by the user interface <NUM> may include a prompt from an operator to begin a priming sequence or a dialysis treatment.

In some embodiments, the processor <NUM> and/or the memory <NUM> are included within the control unit <NUM>. Further, the control unit <NUM> may include one or more capacitive sensors <NUM> that operate with the priming sensor <NUM>. In some examples, the sensors <NUM> are separate from the processor <NUM>. In other examples, the sensors <NUM> may be included within the processor <NUM>.

It should be appreciated that the dialysis machine <NUM> may include additional components for system preparation and/or performing dialysis treatments. The additional components may include pump actuators, compressors, pressure tanks, pneumatic equipment, valve actuators, heaters, online fluid generation equipment, fluid pressure sensors, fluid temperature sensors, conductivity sensors, and air detection sensors. The dialysis machine <NUM> may additionally or alternatively include blood leak detection sensors, filters, dialyzers, balance chambers, sorbent cartridges, etc. In addition, the dialysis machine <NUM> may include one or more network connections (e.g., an Ethernet connection) to enable the processor <NUM> to receive data/prescriptions and transmit dialysis therapy status information to a remote or centralized server via a network (e.g., the Internet). In an embodiment, the control unit <NUM> using the processor <NUM> may create a data structure or log that includes an indication of priming, detection of patient tube state changes, a date/time when the state change occurred, and/or indications of alarms provided.

<FIG> illustrates an embodiment of the priming sensor <NUM> positioned relative to the dialysis machine <NUM> of the example medical fluid delivery system <NUM> of <FIG>, according to an example embodiment of the present disclosure. In the illustrated example, the priming sensor <NUM> is provided on or otherwise connected to a housing <NUM> of the dialysis machine <NUM> via a housing <NUM> of the priming sensor <NUM>. The housing <NUM> is configured to retain the patient tube <NUM> in place to enable measurements to be made. The housing <NUM> may include or form a clip configured to engage the patient tube <NUM>, which may include a cap <NUM>. For example, the housing <NUM> may include a cylindrical opening that corresponds to or aligns with corresponding structure of the tube <NUM> to retain the tube in place. A patient inserts, e.g., snap-fits the tube <NUM> into the housing <NUM> by placing the patient tube <NUM> into an open channel of the housing <NUM>. The patient, in one embodiment, lowers the tube <NUM> until it is seated within the housing <NUM>. While the housing <NUM> is shown as being located on a side of the dialysis machine <NUM>, in other embodiments, the housing <NUM> may be located on a top, front, back, and/or opposing surface of the dialysis machine.

The example cap <NUM> is configured to mechanically connect to an end connector <NUM> of the patient tube <NUM>. The cap <NUM> optionally includes a hydrophobic vent or filter that permits air to vent from the patient tube <NUM> during a priming sequence. The vent or filter, in an embodiment, helps prevents fluid from overflowing out of the patient tube <NUM>. However, overfilling the tube <NUM> may cause the cap <NUM> to separate from the tube. The priming sensor <NUM> is configured to detect when fluid reaches the end connector <NUM> (or just below the connector <NUM>) of the patient tube <NUM> to determine when fluid pumping or gravity priming should stop. In such a case, the hydrophobic vent may not be needed. After a priming sequence has been completed, a patient may disconnect the cap <NUM> from the end connector <NUM>. The patient may then connect the end connector <NUM> of the patient tube <NUM> to a catheter, which is fluidly connected to the patient's peritoneal cavity.

<FIG> also illustrates that the patient tube <NUM> may include a tube clamp <NUM>. The tube clamp <NUM> may be clamped to the tube <NUM> prior to priming to prevent fluid from unintentionally exiting the patient tube <NUM>. The tube clamp <NUM> is disengaged prior to the priming sequence but may be clamped after priming while the patient connects the end connector <NUM> to a catheter (or related transfer set) to begin treatment. The tube clamp <NUM> may optionally be omitted.

<FIG> illustrates the housing <NUM> of the priming sensor <NUM> of <FIG> and <FIG>, according to an example embodiment of the present disclosure. The example housing <NUM> of <FIG> includes a recessed section <NUM> configured to accept and engage the tube <NUM>. The recessed section <NUM> may have a u-shape or semi-circular shape that at least partially encircles the tube <NUM>. The recessed section <NUM> in the illustrated embodiment includes a lip <NUM> configured to receive and secure the tube <NUM> in place. The recessed section <NUM> includes walls configured to enclose or otherwise encase one or more electrodes and/or conductive plates, which are discussed in more detail in connection with <FIG>.

The example housing <NUM> also includes a retainer clip <NUM> (e.g., a member). The example retainer clip <NUM> includes a conductive plate or electrode with an end that is connected to an interior section or the recessed section <NUM>. The retainer clip <NUM> is configured to hold the tube <NUM> within the lip <NUM> of the housing <NUM> when the tube <NUM> is inserted. As such, the example retainer clip <NUM> is configured to cause the tube <NUM> to be properly aligned within the priming sensor <NUM>. The retainer clip <NUM> may be configured to provide a compressive force to further retain the tube <NUM> in place after insertion. As discussed in more detail in connection with <FIG>, the movement of the retainer clip <NUM> towards the recessed section <NUM> when the tube <NUM> is inserted changes a measured capacitance, which is used to detect between a no-tube state and a dry tube state.

The example housing <NUM> also includes exterior walls <NUM>. The exterior walls <NUM> may include one or more shields to prevent or at least reduce electrical field interference within the recessed section <NUM> due to external sources. Additionally or alternatively, the exterior walls <NUM> may enclose or otherwise encase one or more electrodes and/or conductive plates to sense changes to an electric field due to an external source, such as a smartphone or a hand of an operator.

<FIG> illustrate the housing <NUM> of the priming sensor <NUM> of <FIG>, according to example embodiments of the present disclosure. <FIG> shows the priming sensor <NUM> before a tube <NUM> is inserted. As illustrated, the housing <NUM> includes a cutout area <NUM> configured to accommodate or otherwise receive the retainer clip <NUM>. As such, the cutout area <NUM> is dimensioned to correspond to dimensions of the retainer clip <NUM>. A spring force or other compressive force of an electrode or conductive plate holds the retainer clip <NUM> in a closed position.

<FIG> illustrates the priming sensor <NUM> after the tube <NUM> is inserted. In the illustrated example, an operator inserts the tube <NUM> into the priming sensor <NUM>, which causes the retainer clip <NUM> to move to an open position within the cutout area <NUM>. The tube <NUM> is retained within the recessed section <NUM> via the lip <NUM> and/or through a compressive force provided by the retainer clip <NUM>. In the illustrated example of <FIG>, the patient tube <NUM> includes the end connector <NUM> and the cap <NUM>. The recessed section <NUM> of the priming sensor <NUM> is configured to accept or otherwise secure the end connector <NUM> in place.

<FIG> illustrates electrodes and/or conductive plates of the priming sensor <NUM> of <FIG>, according to an example embodiment of the present disclosure. In the illustrated example, a first electrode or metallic sheet <NUM> is provided at a location that is adjacent to a first portion of the tube <NUM> when the tube is inserted. In addition, a second electrode or metallic sheet <NUM> is provided at a location that is adjacent to a second portion of the tube <NUM> when the tube is inserted. The first and second electrodes <NUM> and <NUM> may be included or encased within the housing <NUM> (not shown) of the priming sensor <NUM>. The electrodes <NUM> and <NUM> are separated by a gap <NUM>, which may have a width that is between <NUM> millimeters ("mm") and <NUM> centimeters ("cm)". The electrodes <NUM> and <NUM> may have a width that is between <NUM> and <NUM>. The electrodes <NUM> and <NUM> are connected to a capacitive sensor <NUM> (e.g., a capacitance measuring device), which is configured to measure a capacitance between the electrodes <NUM> and <NUM>. The electrodes <NUM> and <NUM> (and other electrodes disclosed herein) may include conductive plates, copper traces on a flexible PC board or cable, metallic plates, carbon filled conductive plastic, metal plated plastic, plastic sprayed with conductive paint, etc. The capacitive sensor <NUM> (e.g., capacitive sensor <NUM> of <FIG>) may be included within the processor <NUM> or the control unit <NUM> of <FIG> or be provided separately. The capacitive sensor <NUM> may, for example, be provided on an electronics card or printed circuit board provided with the control unit <NUM>. The processor <NUM>, the capacitive sensor <NUM>, and/or the control unit <NUM> is powered via a power source of the dialysis machine <NUM>.

As shown in <FIG>, at a first time, a fluid level <NUM> in the tube <NUM> is elevationally below the electrodes <NUM> and <NUM>. As a result, the capacitance measured at the sensor <NUM> is primarily based on the dielectric values of the air in the tube <NUM> and the tube itself. Later, the fluid level <NUM> rises in the tube <NUM> during a priming sequence to expel the air. As such, the fluid <NUM> flows past the electrodes <NUM> and <NUM>. The presence of the fluid <NUM> in the portion of the tube <NUM> that is adjacent to the electrodes <NUM> and <NUM> reduces an effective distance between the electrodes <NUM> and <NUM>, thereby increasing a value of the capacitance measured by the sensor <NUM>. While the fluid <NUM> does not bridge the gap <NUM> by physically contacting the electrodes <NUM> and <NUM>, the placement of the fluid <NUM> adjacent to the gap <NUM> is sufficient to change the electric field around and between the electrodes <NUM> and <NUM>. Detection of a change in electric field is indicative that the fluid level <NUM> has reached the end of the tube <NUM> at the electrodes <NUM> and <NUM>, which is indicative that the pump <NUM> can stop the priming procedure. Further, the movement of a floating electrode closer to the electrodes <NUM> and <NUM> also increases the measured capacitance, which may be used for detecting the presence of the tube <NUM>.

<FIG> illustrates the priming sensor <NUM> of <FIG>, according to another example embodiment of the present disclosure. In the illustrated example, the sensor <NUM> includes three electrodes and/or conductive plates <NUM>, <NUM>, and <NUM>, which are positioned at different elevational heights with respect to the tube <NUM>. The electrodes <NUM> and <NUM> are electrically connected to a first capacitive sensor 606a, while the electrodes <NUM> and <NUM> are electrically connected to a second capacitive sensor 606b. The capacitive sensors 606a and 606b may be included within the processor <NUM> (and/or the control unit <NUM> and communicatively coupled to the processor <NUM>) of <FIG> or be provided separately.

The capacitive sensors 606a and 606b collectively provide an indication of fluid level. For example, detection of a fluid by the second sensor 606b but not the first sensor 606a is indicative that the fluid level has reached a height in the tube <NUM> greater than the end of the electrode <NUM> but less than a lower end of the electrode <NUM>. Detection of the fluid level at such a level may cause the processor <NUM> of the control unit <NUM> to decrease a pumping speed of the pump <NUM>. Detection of the fluid by the first sensor 606a is indicative that the fluid has reached at least a height in the tube <NUM> that is adjacent to the electrode <NUM>. Detection of the fluid level at this elevation may cause the processor <NUM> of the control unit <NUM> to stop the priming sequence using the pump <NUM>. If neither of the sensors 606a and 606b detects an increase in capacitance, the processor <NUM> of the control unit <NUM> may be configured to cause the pump <NUM> to operate at normal priming speed to prime the tube <NUM> with fluid.

<FIG> illustrates the priming sensor <NUM> of <FIG>, according to further example embodiment of the present disclosure. In this example, a first electrode or conductive plate <NUM> is placed on a first side of the tube <NUM>, while a second electrode or conductive plate <NUM> is placed on a second side of the tube <NUM>. As illustrated, the first electrode <NUM> is placed on a first side of the recessed section <NUM> of the housing <NUM>, which is opposite to a second side of the recessed section <NUM>, which contains the second electrode <NUM>.

The electrodes <NUM> and <NUM> are electrically connected to a capacitive sensor <NUM>, which is configured to measure a capacitance between the electrodes. The measured capacitance includes values that are indicative of the capacitance. As shown in <FIG>, when a fluid is not present, the capacitive sensor <NUM> measures a capacitance of the tube <NUM> and air within the tube. When the fluid displaces the air, the capacitive sensor <NUM> measures a capacitance of the tube <NUM> and the fluid. The capacitance of the tube <NUM> itself is normalized or otherwise neglected when detecting a change in capacitance due to the transition from air to fluid within the tube <NUM>.

In some embodiments, a fluid level may be determined based on the measured capacitance. For instance, the capacitance may be lower when the fluid level in the tube <NUM> is only aligned with a bottom portion or end of the electrodes <NUM> and <NUM> and greater when the fluid level is aligned with the top portion or end of the electrodes. The value of the capacitive may be correlated via a table or other data structure to a height in the tube <NUM>. This value may be used by the processor <NUM> of the control unit <NUM> for gradually decreasing a speed of the pump <NUM> as the fluid level approaches a top (open) end of the tube <NUM>.

<FIG> illustrates the priming sensor <NUM> of <FIG>, according to yet another example embodiment of the present disclosure. Similar to the example of <FIG>, the electrodes <NUM> and <NUM> are positioned opposite of one another. However, as shown in a plan view <NUM>, the electrode <NUM> is included within the retaining clip <NUM>. As such, the electrode <NUM> is moveable relative to the electrodes <NUM>, <NUM> and <NUM>, which are held stationary via the housing <NUM>. An end or base of the electrode <NUM> is connected to a base or middle portion of the recessed section <NUM>. The retaining clip <NUM> is configured to pivot or bend at the end of the electrode <NUM>, thereby enabling the clip <NUM> to be moved between opened and closed positions. Further, the biased nature of the electrode <NUM> to return to its initial position within the recessed section <NUM> causes the retaining clip <NUM> to provide a spring force on the tube <NUM> when inserted into the priming sensor <NUM>. It should be appreciated that in some examples, the electrode <NUM> is not electrically connected to other portions of the priming sensor <NUM>, thereby enabling it to float electrically.

The example priming sensor <NUM> of <FIG> also includes the electrodes <NUM> and <NUM>. As shown in plan view <NUM>, the electrodes <NUM> and <NUM> are provided on a side of the recessed section <NUM>, which is opposite to that of the electrode <NUM>. The electrodes <NUM> and <NUM> are stationary and are configured to at least partially encircle the tube <NUM>.

Similar to the example discussed in connection with <FIG>, the electrodes <NUM> and <NUM> are positioned at different elevational heights relative to each other. In the illustrated example, the electrode <NUM> is placed at a greater height or elevation than is the electrode <NUM>, providing a gap therebetween. The electrodes <NUM> and <NUM> may have the same width or different widths.

The electrodes <NUM> and <NUM> are electrically connected to a first capacitive sensor 606a, which is configured to measure a capacitance value between the electrodes <NUM> and <NUM>. In the illustrated example, the capacitive sensor 606a is configured to detect a change between the no-tube state and the dry tube state. In the illustrated example, the capacitive sensor 606a is configured to detect a capacitance change as a result of the electrode <NUM> being moved closer to the electrodes <NUM> and <NUM> when, for example, the tube <NUM> is inserted within the priming sensor <NUM>. Movement of the electrode <NUM> towards the electrodes <NUM> and <NUM> causes the measured capacitance to increase, which is indicative that the tube <NUM> has been inserted within the priming sensor <NUM>.

In some embodiments, the capacitive sensor 606a may also be used to detect a capacitance change when a dialysis fluid level rises to bridge the gap between the electrodes <NUM> and <NUM>. As such, the capacitive sensor 606a may be configured to additionally detect transitions between a dry tube and a wet tube. Outputs from the sensor 606a are used by the processor <NUM> of the control unit <NUM> to determine the dry tube state and the wet tube state, as discussed in connection with <FIG>.

As shown in <FIG>, the electrodes <NUM> and <NUM> are electrically connected to a second capacitive sensor 606b. In the illustrated example, the capacitive sensor 606b is configured to detect a capacitance increase as a result of the fluid level rising between the electrodes <NUM> and <NUM>. The capacitive sensor 606b is used to detect transitions between a dry tube state and a wet tube state.

Similarly, electrodes <NUM> and <NUM> are electrically connected to a third capacitive sensor 606c. The third capacitive sensor 606c is configured to detect a capacitance increase as a result of fluid rising between the electrodes <NUM> and <NUM>. The capacitive sensor 606c is used to detect transitions between a dry tube state and a wet tube state.

In some embodiments, the outputs (or values indicative of measured capacitances) of the capacitive sensors 606b and 606c are added together or otherwise combined by the processor <NUM> of the control unit <NUM> for detecting the dry tube state and the wet tube state. In some embodiments, the processor <NUM> may compare the outputs from the capacitive sensors 606b and 606c for determining a fluid level in the tube <NUM>. For example, a significant difference between the measured capacitances is indicative that the fluid level in the tube <NUM> has not yet reached a height of the electrode <NUM> but has reached the height of the electrode <NUM>. Detection of the fluid at this level may cause the processor <NUM> to reduce a pumping speed of the pump <NUM>.

<FIG> show a plan view of the priming sensor <NUM>, according to an example embodiment of the present disclosure. <FIG> shows the retaining clip <NUM> and the electrode <NUM> in a closed and resting position when the tube <NUM> is not inserted into the priming sensor <NUM>. <FIG> also shows a base or end of the electrode <NUM> connected to a middle-section or base of the recessed section <NUM>. <FIG> shows the electrode <NUM>, including the retaining clip <NUM>, bent, pivoted, or otherwise moved towards the electrode <NUM> as a result of the tube <NUM> being inserted into the priming sensor <NUM>. The retaining clip <NUM> and/or the electrode <NUM> is configured such that the tube <NUM> can only be inserted into a desired alignment. The retaining clip <NUM> and/or the electrode <NUM> may include, for example, a front end that is angled for receiving and directing the tube <NUM> to a middle of the recessed section <NUM>. As discussed above in connection with <FIG>, placement of the tube <NUM> in the recessed section <NUM> causes the electrode <NUM> to move towards electrodes <NUM> and <NUM>, thereby increasing the measured capacitance.

<FIG> shows a circuit diagram <NUM> for one embodiment of the capacitors formed by the electrodes <NUM>, <NUM>, <NUM>, and <NUM> of <FIG>, according to an example embodiment of the present disclosure. As shown, the electrodes <NUM> and <NUM> form a first capacitor while electrodes <NUM> and <NUM> form a second, parallel capacitor. The capacitance of the first and second capacitors is based on a position of the electrode <NUM> relative to the electrodes <NUM> and <NUM>. The electrodes <NUM> and <NUM>, as discussed herein, form a third capacitor.

The example processor <NUM> of the control unit <NUM> of <FIG> is configured, in part, to determine a tube state based on capacitance measured by one or more capacitive sensors. <FIG> shows the processor <NUM> of <FIG>, according to an example embodiment of the present disclosure. The processor <NUM> includes a first processing device 120a and a second processing device 120b. The first processing device 120a is provided on a circuit board or processor board <NUM>. In the example, the first processing device 120a is electrically connected to the electrodes <NUM> and <NUM> via General Purpose Input Output ("GPIO") traces or lines. In some instances, current sources (or one or more power sources) may be connected to the GPIO lines to provide current to enable the capacitance measurements. The current sources may provide, for example, a current of <NUM> nA, <NUM> nA, <NUM> nA, <NUM> nA, <NUM> nA, etc..

Also shown in <FIG>, the electrode <NUM> is electrically connected to ground. The ground may be shared in common with a ground for the processing device 120a, such that the processing device 120a is electrically connected to the electrode <NUM> via ground. In other embodiments, the electrode <NUM> is instead connected to the processing device 120a via a third GPIO line or trace. Further, as discussed above, the electrode <NUM> is not electrically connected to the processing device 120a and is therefore permitted to electrically float.

The processing device 120a includes and/or operates with the capacitive sensors 606a, 606b, and 606c, which measure capacitance via the GPIO lines. For example, the sensor 606a operates with the processing device 120a to measure a capacitance between the electrodes <NUM> and <NUM> by determining a capacitance between the GPIO lines. The sensor 606b operates with the processing device 120a to measure a capacitance between the electrodes <NUM> and <NUM> by determining a capacitance between the second GPIO line and ground. The sensor 606c operates with the processing device 120a to measure a capacitance between the electrodes <NUM> and <NUM> by determining a capacitance between the first GPIO line and ground.

<FIG> shows a graph <NUM> illustrating example capacitance values measured by the sensors 606a, 606b, and 606c of <FIG> over a time period, according to an example embodiment of the present disclosure. The graph <NUM> shows units of normalized capacitance over <NUM> seconds. The capacitance may be normalized from measured values having an order of magnitude of femtofarads ("fF") or picofarads ("pF"). The graph <NUM> shows a transition between a dry tube state and a wet tube state, as measured by the capacitive sensors 606b and 606c. As shown, the normalized capacitance changes by about <NUM> units within a few tenths of a second as the liquid level in the tube <NUM> reaches the electrodes <NUM>, <NUM>, and <NUM>. The magnitude of the capacitance is substantially level or consistent after the wet state is reached. When the liquid level is reduced, the capacitance quickly falls off to return to a normalized value of '<NUM>,' thereby producing a square-shaped waveform. As can be appreciated, the significant capacitance difference between the states provides a robust signal-to-noise ratio that is greater than <NUM>: <NUM>, providing for accurate tube state detection. It should be appreciated that the graph <NUM> is similar in magnitude and shape for transitions between the no-tube state and the dry tube state.

Returning to <FIG>, after measuring a capacitance, the first processing device 120a is configured to transmit one or more signals or messages that are indicative of the capacitance to the second processing device 120b. In the example, the second processing device 120b transmits input instructions or signals via separate input lines. The first processing device 120a may use the input instructions or signals for sampling or performing capacitance measurements. For example, a first input from the second processing device 120b may instruct the first processing device 120a to measure a capacitance of the first capacitive sensor 606a, while the second input may instruct the first processing device 120a to measure a capacitance of the second capacitive sensor 606b, while the third input may instruct the first processing device 120a to measure a capacitance of the third capacitive sensor 606c.

In some embodiments, the first processing device 120a is configured to determine a tube state based on the measured capacitance values determined via the GPIO lines. The first processing device 120a transmits an indication of each tube state or an indication of a tube state change to the second processing device 120b via, for example, a pulse-width modulated ("PWM") signal or an analog signal produced by a digital-to-analog converter ("DAC") within the first processing device 120a. In alternative examples, the PWM signal may be replaced by a digital signal or instruction that is indicative of the tube state.

In some embodiments, the first processing device 120a is configured to sample or perform multiple capacitance measurements before conclusively determining that a tube state has changed. For example, if a threshold number of measurements (e.g., one, two, three, five, ten, etc.) are indicative of the same tube state within a threshold time period (e.g., <NUM>, <NUM>, <NUM>, <NUM>, ms, <NUM> second, <NUM> seconds, <NUM> seconds, etc.), the first processing device 120a determines the tube state has in fact changed. If at least one of the thresholds is not met, the processing device 120a refrains from determining a tube state change. The above-situation may occur when electrical interference is present due to an operator's hand or electronic device.

Alternatively, the first processing device 120a transmits an indication of the measured capacitances to the second processing device 120b via a PWM signal or an analog signal produced by the DAC within the first processing device 120a. A pulse width may correspond to a value of the measured capacitance. In alternative examples, the PWM signal may be replaced by a digital signal or instruction that is indicative of measured capacitance. After receiving capacitance values from the first processing device 120a, the second processing device 120b is configured to determine a tube state. In some examples, the processing device 120b may sample or perform multiple capacitance measurements (by transmitting messages via the separate input lines to the first processing device 120a) for determining tube state. If a threshold number of measurements (e.g., one, two, three, five, ten, etc.) are indicative of the same tube state within a threshold time period (e.g., <NUM>, <NUM>, <NUM>, <NUM>, ms, <NUM> second, <NUM> seconds, <NUM> seconds, etc.), the second processing device 120b determines the tube state has in fact changed. If at least one of the thresholds is not met, the processing device 120b refrains from determining a tube state change.

<FIG> illustrates an example procedure <NUM> for determining a tube state of the patient tube <NUM> of <FIG>, according to an example embodiment of the present disclosure. The example processor <NUM> of the control unit <NUM> is configured to execute or operate the procedure <NUM> shown in <FIG>. To begin, the example processor <NUM> receives an indication or determines that a patient is to start a dialysis treatment (block <NUM>). The example processor <NUM> may receive an input via the user interface <NUM> that a patient has selected to begin a treatment. Alternatively, the processor <NUM> may determine via an electronically stored schedule that a patient is to undergo a dialysis treatment. To prepare for the treatment, the example processor <NUM> operates a setup routine in one embodiment, which may include connecting tubes to appropriate containers and performing a priming procedure. When it is time to prime the patient tube <NUM>, the example processor <NUM> transmits a message <NUM> for display via the user interface <NUM> that the patient is to inset the patient tube <NUM> into the priming sensor <NUM> (block <NUM>). <FIG> illustrates an example screen layout <NUM> that may be displayed by the user interface <NUM> based on the message <NUM>. The screen layout <NUM> includes text and an illustration regarding how the patient tube <NUM> is to be placed within the priming sensor <NUM>.

To determine if the patient correctly inserted the tube <NUM> into the priming sensor <NUM>, the example processor <NUM> is configured to perform one or more capacitive measurements to determine a tube state (block <NUM>). For each capacitive measurement performed, the processor <NUM> receives sampled output data <NUM> from one or more of the capacitive sensors <NUM>, which is processed to determine a tube state, as discussed above in connection with <FIG>. If the no-tube state is detected, the processor <NUM> is configured to transmit one or more messages <NUM> indicative that the patient tube <NUM> is missing. <FIG> illustrates a diagram of a screen layout <NUM> that may be displayed by the user interface <NUM> based on the message <NUM>. The screen layout <NUM> includes a pop-up window alerting the patient that the patient tube <NUM> has not been inserted.

Returning to <FIG>, if a dry tube state is detected, the example processor <NUM> transmits one or more messages <NUM> indicative that the patient is to connect a tube to a fluid source (block <NUM>). In other embodiments, the message <NUM> may instruct a patient to begin a priming sequence. <FIG> shows a diagram of a screen layout <NUM> that may be displayed by the user interface <NUM> based on the message <NUM>. The screen layout <NUM> includes text and images regarding how a fluid source is to be connected to one or more source tubes of a dialysis machine. After the patient has connected the tubes, the patient may select the priming button shown in the screen layout <NUM>. Selection of the priming button provides an indication for the processor <NUM> to begin a priming sequence (block <NUM>). The priming sequence includes causing at least one pump <NUM> to move dialysis fluid from at least one source container <NUM> to the patient tube <NUM>. During this sequence, the processor <NUM> receives sampled output data <NUM> from performing multiple capacitance measurements or sampling of capacitance measurements that are conducted by the capacitive sensors <NUM> (block <NUM>). In addition, during this sequence, the processor <NUM> may cause a screen layout <NUM> shown in <FIG> to be displayed on the user interface <NUM>, which is indicative that a priming sequence is being run.

For each detection of a dry tube state, the processor <NUM> may increment a threshold counter and determine whether the counter exceeds a threshold (block <NUM>). If the threshold is not exceeded within a specified time period (e.g., <NUM>, <NUM>, <NUM> second, <NUM> seconds, <NUM> seconds, <NUM> seconds, <NUM> seconds, etc.), the patient tube <NUM> is not able to prime within an expected time period and may have an occlusion, leak, constriction, or other condition that is preventing dialysis fluid from filling the tube. In an attempt to correct the situation, the processor <NUM> is configured to transmit one or more messages <NUM>, which causes screen layout <NUM> of <FIG> to be displayed. In addition, an alarm may be activated. The screen layout <NUM> includes text indicative of the priming error and instructions for the patient to check the tubes from the source fluid and the patient tube <NUM>. After a patient has identified and corrected the issue with the tubes, the patient may select the next button to re-start the priming sequence.

Returning to block <NUM>, if a wet tube state is detected within a threshold time, the example processor <NUM> may be configured to stop the pump <NUM> from priming (block <NUM>). In some embodiments, the example processor <NUM> is configured to confirm that the prime has been correctly performed. The example processor <NUM> may also transmit one or more messages <NUM> with information instructing the patient to connect the patient tube <NUM> to a patient line set and/or catheter to begin treatment (block <NUM>). <FIG> illustrates a diagram of a screen layout <NUM> that may be displayed by the user interface <NUM> based on the message <NUM>. The screen layout <NUM> includes text and an image providing a patient information regarding how to connect the patient tube <NUM> to a line set or catheter.

Returning to <FIG>, the example processor <NUM> is configured to use the priming sensor <NUM> to determine if the patient tube <NUM> is still present in the sensor (block <NUM>). The processor <NUM> receives one or more sets of sampled output data <NUM> to determine if the tube is still in the priming sensor <NUM>. If the tube is still present, the processor <NUM> transmits one or more messages <NUM> indicative that the patient is to remove the tube from the priming sensor <NUM>. <FIG> illustrates a diagram of a screen layout <NUM> that may be displayed by the user interface <NUM> based on the message <NUM>. The screen layout <NUM> includes a pop-up window providing a warning that that the patient tube has not been removed from the priming sensor for connection to a line set or catheter. If the patient tube <NUM> is no longer detected, the example processor <NUM> is configured to end the priming sequence and/or enable the dialysis therapy to begin.

<FIG> shows a diagram of an example procedure <NUM> configured to determine a tube state of the patient tube <NUM> for a priming sequence, according to an example embodiment of the present disclosure. The example procedure <NUM> may be executed or performed by the processor <NUM> of <FIG>. Further, the processor <NUM> may operate according to one or more instructions stored in the memory <NUM>, which when executed by the processor <NUM>, cause the processor <NUM> to perform the described operations. In some embodiments, the processor <NUM> may additionally normalize the measured capacitance values.

The example procedure <NUM> begins when the processor <NUM> performs a priming sequence and provides power to the priming sensor <NUM> (block <NUM>). The example processor <NUM> calibrates the capacitive sensor 606a of <FIG> (block <NUM>). The processor <NUM> may calibrate the sensor 606a by determining steady state measured capacitance. The processor <NUM> may determine an average of the measured capacitance values for calculating a baseline value <NUM>. After calibration, the processor <NUM> stores the determined baseline capacitance value <NUM> to the memory <NUM>.

The processor <NUM> then computes a sense threshold T (block <NUM>). The threshold T is a capacitance value that is greater than the baseline value <NUM>. In some embodiments, the processor <NUM> determines the threshold T as being 2x, 3x, 4x, 5x, 7x, 10x, 15x, 20x, etc., greater than the baseline value <NUM>. In other embodiments, the processor <NUM> determines the threshold T as being a specified number of fF or pF above the baseline value. Measured capacitance values below the threshold T are determined by the processor <NUM> to correspond to a no-tube state, while measured capacitance values above the threshold T are determined by the processor <NUM> to correspond to a dry tube state. For instance, the processor <NUM> compares measured capacitance values from the sensor 606a to the threshold T (block <NUM>). If the measured capacitance values are less than the threshold T, the processor <NUM> determines the measured values correspond to the no-tube state (block <NUM>). In some instances, the processor <NUM> may also update a counter, where no detections of a no-tube state within a specified time period may cause the processor <NUM> to output an error message or activate an alert. The processor <NUM> then continues to compare (or sample) subsequent measured capacitance values from the capacitive sensor 606a to the threshold T.

Returning to block <NUM>, if the measured capacitance values are greater than or equal to threshold T, the processor <NUM> determines the measured value corresponds to a dry tube state (block <NUM>). In some instances, the processor <NUM> may only determine a dry tube state if a threshold number of dry state tube detections are made within a specified time period (e.g., two, five, or ten detections within <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, etc.).

The processor <NUM> next calibrates the capacitive sensor 606b and/or 606c of <FIG> (block <NUM>). In some embodiments, the processor <NUM> calibrates the capacitive sensors 606a, 606b, and 606c at substantially the same time or at the same time within the example procedure <NUM>. The processor <NUM> may calibrate the sensor 606b and/or 606c by determining steady state measured capacitances. The processor <NUM> may determine an average of the measured capacitance values for calculating a baseline value <NUM>. After calibration, the processor <NUM> stores the determined baseline capacitance value <NUM> to the memory <NUM>.

The processor <NUM> of the control unit <NUM> then computes a sense threshold W (block <NUM>). The threshold W is a capacitance value that is greater than the baseline value <NUM>. In some embodiments, the processor <NUM> determines the threshold W as being 2x, 3x, 4x, 5x, 7x, 10x, 15x, 20x, etc., greater than the baseline value <NUM>. In other embodiments, the processor <NUM> determines the threshold W as being a specified number of fF or pF above the baseline value. Measured capacitance values below the threshold W are determined by the processor <NUM> to correspond to a dry tube state, while measured capacitance values above the threshold W are determined by the processor <NUM> to correspond to a wet tube state.

After the threshold W is determined, the processor <NUM> is ready to determine a tube state. As shown in <FIG>, the processor <NUM> is configured to compare measured capacitance values from the sensor 606a to the threshold T (block <NUM>). If the measured capacitance values are less than the threshold T, the processor <NUM> determines the measured values correspond to the no-tube state (block <NUM>). The processor <NUM> continues this loop until the measured capacitance values are greater than or equal to the threshold T. The processor <NUM> then compares measured capacitance values from the sensor 606b and/or 606c to the threshold W (block <NUM>). In some instances, the processor <NUM> may combine the measured capacitance values from the sensors 606b and 606c for the baseline value <NUM>, the threshold W, and state detection. If the measured capacitance values are less than the threshold W, the processor <NUM> determines the measured values correspond to the dry tube state (block <NUM>). The processor <NUM> may return to block <NUM> and determine if the tube is still present in the priming sensor <NUM> or determine if the tube has been removed. In some instances, the processor <NUM> may also update a counter, where zero detections of a wet tube state within a specified time period may cause the processor <NUM> to output an error message or activate an alert indicative of an occlusion, tube leak, etc. The processor <NUM> then continues to compare (or sample) subsequent measured capacitance values from the capacitive sensors 606b and/or 606c to the threshold W.

Returning to block <NUM>, if the measured capacitance values are greater than or equal to threshold W, the processor <NUM> determines the measured value corresponds to a wet tube state (block <NUM>). In some instances, the processor <NUM> of the control unit <NUM> may only determine a wet tube state if a threshold number of wet state tube detections are made within a specified time period (e.g., two, five, or ten detections within <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, etc.). After detecting a wet tube state, the example processor <NUM> may end a priming sequence, thereby ending the example procedure <NUM>. Alternatively, the processor <NUM> returns to block <NUM> and determines if the tube has been removed from the priming sensor <NUM>.

<FIG> shows a diagram of the priming sensor <NUM> of <FIG>, according to another example embodiment of the present disclosure. In the illustrated example, the priming sensor <NUM> includes a housing <NUM> that is provided in a u-shape. The housing <NUM> includes a first arm or side <NUM> and a second arm or side <NUM>. The housing <NUM> also includes a joint or hinge <NUM> that enables the second arm or side <NUM> to rotate or pivot with respect to the first arm or side <NUM> or a base <NUM> of the u-shaped housing <NUM> (e.g., a third side).

In the illustrated example, the first arm or side <NUM> includes conductive plates <NUM> and <NUM>. The plates may be solid and placed adjacent to the other. Alternatively, the plates may be interleaved in a comb or finger configuration to provide a relatively broad sensitive area. The conductive plate <NUM> is provided at a first height relative to the patient tube <NUM> and the conductive plate <NUM> is provided at a second height, below the conductive plate <NUM>. In some examples, the plates <NUM> and <NUM> have the same lengths, widths, and/or heights. Further, the plates <NUM> may be separated by a few millimeters up to a few centimeters. A capacitive sensor <NUM> is configured to measure a capacitance between the plates <NUM> and <NUM>. The processor <NUM> is configured to use the capacitance values measured by the sensor <NUM> to discriminate between the wet tube state and the dry tube state by determining when capacitance values change as a result of cleansing fluid in the tube <NUM> bridging the gap between the plates <NUM> and <NUM>.

<FIG> also shows that the second side or arm <NUM> of the housing <NUM> includes conductive plate <NUM> while the base side <NUM> of the housing includes conductive plates <NUM> and <NUM>. The conductive plates <NUM> and <NUM> are electrically connected to a capacitive sensor <NUM>, which is configured to measure capacitance between the plates <NUM> and <NUM>. The conductive plate <NUM> is configured to electrically float. The conductive plates <NUM> and <NUM> and sensor <NUM> are configured to detect (via the processor <NUM>) when the conductive plate <NUM> is moved closer to the plates <NUM> and <NUM> by measuring an increase in capacitance.

<FIG> show diagrams illustrating how the joint or hinge <NUM> enables the second arm or side <NUM> to rotate or pivot with respect to the third arm or side <NUM>. The example hinge <NUM> may be molded as part of the housing <NUM> as a living hinge. In other examples, the hinge <NUM> may include a barrel hinge, a pivot hinge, a case hinge, or combinations thereof. In some instances, the hinge <NUM> may be part of a member (e.g., the second arm <NUM>) that is configured for a desired movement upon insertion of a tube <NUM> into the housing <NUM> of the priming sensor <NUM>. In this embodiment, the conductive plates <NUM> and <NUM> may be provided on the third side <NUM> of the housing <NUM> that forms a base of the u-shape, whereby the hinge <NUM> connects the second side <NUM> to the third side <NUM>.

<FIG> shows the second side <NUM> rotated, via the hinge <NUM>, to be parallel with the first side <NUM> of the housing <NUM> when the tube <NUM> is inserted therein. In this configuration, the conductive plate <NUM> is moved closer towards the conductive plates <NUM> and <NUM>, which causes the capacitance measured by the sensor <NUM> to increase. In the illustrated example, the sensor <NUM> measures the capacitance between the conductive plates <NUM> and <NUM>. Moving the conductive plate <NUM> closer towards the plates <NUM> and <NUM> causes the capacitance between (and around) the plates <NUM> and <NUM> to increase. Accordingly, the processor <NUM> uses output from the sensor <NUM> to discriminate between a dry tube state and a no-tube state.

<FIG> shows an example when the tube <NUM> is removed from the housing <NUM>. In this example, the second side <NUM> is rotated or pivoted at the hinge <NUM> to be angled toward or be closer to the first side <NUM>. In this configuration, the conductive plate <NUM> is moved away from the conductive plates <NUM> and <NUM>, which causes the capacitance measured by the sensor <NUM> to decrease. The movement of the second side <NUM> increases an area of a gap <NUM> between the conductive plates <NUM>, <NUM>, and <NUM>. In some embodiments, the gap <NUM> may include air or a compressible foam that fills the gap between the second side <NUM> and the third side <NUM> of the housing <NUM>.

Claim 1:
A peritoneal dialysis apparatus (<NUM>) comprising:
a patient tube (<NUM>) configured to receive dialysis fluid from a source of dialysis fluid;
at least one pump (<NUM>) configured to move dialysis fluid from the source to the patient tube during a priming sequence;
a priming sensor (<NUM>) including a housing (<NUM>) having a recessed section (<NUM>) configured to accept a portion of the patient tube, the recessed section of the housing including
a first side including a first conductive plate (<NUM>),
a member (<NUM>) including a second conductive plate (<NUM>), the member being moveably connected to a second side of the recessed section and configured for a desired movement upon insertion of the portion of the patient tube into the housing of the priming sensor, and
a third side opposing the first side, the third side including
a third conductive plate (<NUM>) disposed across from a top portion of the first conductive plate (<NUM>), and
a fourth conductive plate (<NUM>) disposed across from a bottom portion of the first conductive plate (<NUM>);
a first capacitive sensor (606b) positioned and arranged to measure a first capacitance between the first conductive plate (<NUM>) and the third conductive plate (<NUM>);
a second capacitive sensor (606a) positioned and arranged to measure a second capacitance between the third conductive plate (<NUM>) and the fourth conductive plate (<NUM>); and
a processor (<NUM>) configured to operate with the at least one pump, the first capacitive sensor, and the second capacitive sensor, the processor configured to
use the measured second capacitance to determine a first transition between (i) a no-tube state and (ii) a dry tube state,
use the measured first capacitance to determine a second transition between (ii) the dry tube state and (iii) a wet tube state,
cause the at least one pump to pump the fluid through to the patient tube for the priming sequence after the dry tube state is determined, and
transmit a message indicative that the patient tube is primed after the wet tube state is determined.