Hemodialysis system reservoir level sensor

Abstract

A portable hemodialysis system is provided that includes: a dialyzer, a closed-loop blood flow path that transports blood from a patient to the dialyzer and back to the patient, and a closed-loop dialysate flow path that transports dialysate through the dialyzer. In addition, the hemodialysis system includes two reservoirs that can be alternately placed in the dialysis flow path using various controllable fluid valves. The weight of each reservoir, and therefore the level of the dialysate in each reservoir, is measured by a preferred level sensor having a lever arm, a load cell, and a tilt sensor. The load cell and the tilt sensor are electrically connected to a processor for sending force measurements and tilt measurements to the processor. The processor can analyze the tilt measurements to correct any inaccurate measurements of the load cell caused by tilt.

Description

Technical Field

[0001] The present invention relates to an artificial kidney system for providing dialysis. More particularly, the present invention relates to a hemodialysis system including a reservoir level sensor, which significantly improves hemodialysis safety, thereby providing hemodialysis to a wider patient population and reducing the overall cost of hemodialysis. Background Art

[0002] Applicants hereby incorporate by reference any and all patents and published patent applications referred to or mentioned in this application.

[0003] Hemodialysis is a medical procedure used to achieve extracorporeal removal of waste products (including creatine, urea, and free water) from a patient's blood, involving the diffusion of solutes across a semipermeable membrane. Failure to properly remove these waste products can lead to kidney failure.

[0004] During hemodialysis, a patient's blood is removed through an arterial line, processed by a dialysis machine, and then returned to the body through a venous line. The dialysis machine includes a dialyzer containing a large number of hollow fibers that form a semipermeable membrane through which the blood is transported. In addition, the dialysis machine uses a dialysate that is also pumped through the dialyzer and contains appropriate amounts of electrolytes and other essential components (such as glucose).

[0005] Typically, the dialysate is prepared by mixing water with appropriate proportions of an acid concentrate and a bicarbonate concentrate. Preferably, the acid concentrate and bicarbonate concentrate are kept separate until final mixing prior to use in the dialyzer, as the calcium and magnesium in the acid concentrate precipitate when in contact with the high bicarbonate content of the bicarbonate concentrate. The dialysate may also include appropriate levels of sodium, potassium, chloride, and glucose.

[0006] The dialysis process across the membrane is achieved by a combination of diffusion and convection. Diffusion requires molecules to migrate from areas of high concentration to areas of low concentration through random motion. Convection, meanwhile, requires the movement of solutes, typically in response to differences in hydrostatic pressure. The fibers that form the semipermeable membrane separate plasma from the dialysate and provide a large surface area for diffusion, allowing waste products including urea, potassium, and phosphate to permeate into the dialysate while preventing larger molecules (such as blood cells, polypeptides, and certain proteins) from transferring into the dialysate.

[0007] Typically, the dialysate flows in an extracorporeal circuit in a direction opposite to the direction of blood flow. Countercurrent flow maintains a concentration gradient across the semipermeable membrane, thereby improving dialysis efficiency. In some cases, hemodialysis can be configured for fluid removal, also known as ultrafiltration. Ultrafiltration is typically achieved by reducing the hydrostatic pressure of the dialysate compartment of the dialyzer, thereby allowing water containing dissolved solutes (including electrolytes and other permeable substances) to move from plasma to the dialysate across the membrane. In rare cases, the fluid in the dialysate flow path portion of the dialyzer is higher than the blood flow portion, causing the fluid to move from the dialysis flow path to the blood flow path. This is typically referred to as reverse ultrafiltration. Because ultrafiltration and reverse ultrafiltration increase the risk to the patient, ultrafiltration and reverse ultrafiltration are typically performed under the supervision of trained medical staff.

[0008] Unfortunately, hemodialysis has many disadvantages. An arteriovenous fistula is the most common access point. To create the fistula, doctors connect an artery and a vein. Because this bypasses the patient's capillaries, blood flows rapidly. For each dialysis session, the fistula must be punctured with a large needle to transfer blood to and from the dialyzer. Typically, this procedure is performed three times a week in a dedicated outpatient setting, each lasting three to four hours. To a lesser extent, patients perform hemodialysis at home. Home dialysis is typically performed six days a week for two hours a day. However, home hemodialysis requires more frequent treatments.

[0009] Home hemodialysis presents other disadvantages as well. Current home hemodialysis systems are large, complex, intimidating, and difficult to operate. The equipment requires extensive training. Home hemodialysis systems are currently too large to be portable, which prevents hemodialysis patients from traveling. Home hemodialysis systems are expensive and require a high initial capital investment, especially compared to in-center hemodialysis, which does not require patients to pay for the machine. Current home hemodialysis systems do not adequately provide for the reuse of supplies, making home hemodialysis less financially viable for healthcare providers. Due to the above-mentioned disadvantages, few motivated patients are willing to undertake the drudgery of home hemodialysis.

[0010] Therefore, there is a great need for a hemodialysis system that is transportable, lightweight, easy to use, patient-friendly and can therefore be used in the clinic or at home.

[0011] Furthermore, it would be desirable to provide a hemodialysis system that has no single points of failure in the pump, motor, tubing, or electronics that could endanger the patient.

[0012] Furthermore, it would be desirable to provide a hemodialysis system that can be used in multiple modes, such as with a filter to clean the dialysate or without a filter.

[0013] In another aspect, it is desirable to provide a hemodialysis system including a reservoir having a level sensor for detecting whether the reservoir has sufficient dialysate for treatment, including for dialysis, ultrafiltration, and reverse ultrafiltration.

[0014] In yet another aspect, it is desirable to provide a hemodialysis system comprising a reservoir having a fluid level sensor for detecting the presence of a fault condition during treatment, such as a loss of dialysate or an increase in fluid in the dialysate reservoir, which may indicate a fault in the dialysis membrane.

[0015] Aspects of the present invention satisfy these needs and provide further related advantages as described in the following summary. Summary of the Invention

[0016] According to a first aspect of the present invention, there is provided a hemodialysis system comprising: an arterial blood line for connecting to a patient's artery to collect blood from the patient, a venous blood line for connecting to a patient's vein to return blood to the patient, a reusable dialysis machine, and a disposable dialyzer.

[0017] Arterial and venous blood lines can be of typical configurations known to those skilled in the art. For example, an arterial blood line can be a conventional flexible hollow tube connected to a needle for collecting blood from a patient's artery. Similarly, a venous blood line can be a conventional flexible tube and needle for returning blood to a patient's vein. Various configurations and surgical procedures can be used to obtain blood from a patient, including intravenous catheters, arteriovenous fistulas, or synthetic grafts.

[0018] Preferably, the disposable dialyzer has a construction and design known to those skilled in the art, including a blood flow path and a dialysate flow path. The term "flow path" is intended to refer to one or more fluid conduits, also referred to as channels, for transporting fluid. The conduits can be constructed in any manner as determined by those skilled in the art, for example including flexible medical tubing or non-flexible hollow metal or plastic housings. The blood flow path transports blood in a closed-loop system by being connected to an arterial blood line and a venous blood line that transport blood from the patient to the dialyzer and back to the patient. At the same time, the dialysate flow path transports dialysate from a dialysate supply source to the dialyzer and back to the dialysate supply source in a closed-loop system. Both the blood flow path and the dialysate flow path pass through the dialyzer, but the flow paths are separated by the semipermeable membrane of the dialyzer.

[0019] Preferably, the hemodialysis system includes a reservoir for storing dialysate solution. The reservoir is connected to the dialysate flow path of the hemodialysis system to form a closed-loop system for transporting the dialysate from the reservoir to the dialyzer of the hemodialysis system and returning to the reservoir. More preferably, the hemodialysis system has two (or more) dialysate reservoirs that can be alternately placed in the dialysate flow path. When a reservoir has contaminated dialysate, other reservoirs can be used to continue dialysis treatment while the reservoir with contaminated dialysate is emptied and refilled. The reservoir can be any size required by the clinician to perform appropriate hemodialysis treatment. However, it is preferred that the two reservoirs have the same size and be small enough to make the dialysis machine easy to carry. An acceptable reservoir capacity is 0.5 liters to 5.0 liters.

[0020] The hemodialysis system preferably has one or more heaters thermally coupled to the reservoir for heating the dialysate stored in the reservoir. In addition, the hemodialysis system includes a temperature sensor for measuring the temperature of the dialysate in the reservoir. The hemodialysis system preferably has a level sensor for detecting the level of the fluid in the reservoir. The fluid level sensor can be any type of sensor for determining the amount of fluid in the reservoir. Acceptable level sensors include magnetic or mechanical float sensors, conductive sensors, ultrasonic sensors, optical interfaces, and weight measurement sensors (e.g., a scale or load cell for measuring the weight of the dialysate in the reservoir).

[0021] In a preferred embodiment, the reservoir level sensor includes a lever arm pivotally secured to the hemodialysis machine housing. The lever arm includes a horizontal member cantilevered outwardly from the machine housing, and a vertical member engaging the horizontal member of the lever arm at (or near) the pivot point of the lever arm and extending downwardly adjacent to the hemodialysis machine housing. The distal end of the horizontal member includes an axis, post, or hook from which the reservoir is suspended. Preferably, the reservoir is in the form of a conventional dialysate bag including a hole or ring at the upper end of the bag for suspending the storage bag from the distal end of the horizontal member. If the reservoir does not have a hole or ring or is not configured as a flexible bag, one skilled in the art may select other fastener configurations for suspending the dialysate reservoir to the horizontal member of the lever arm.

[0022] In addition to the lever arm, the liquid level sensor also includes a load cell connected to the electronic processor of the hemodialysis machine. The load cell can be any type of sensor, such as a transducer or a strain gauge, which can convert a force such as tension, compression, pressure or torque into an electrical signal that can be measured and standardized. As the force applied to the load cell increases, the electrical signal changes proportionally. Preferably, the load cell is fixed to or on the housing of the hemodialysis machine. Importantly, the load cell is positioned to engage with the vertical member of the lever arm so that when the vertical member presses against the load cell, the load cell can convert the force into an electrical signal that is transmitted to the processor.

[0023] Because the lever arm is pivotally secured to the hemodialysis machine's housing at a pivot point, any weight on the lever arm's horizontal member causes the lever arm to rotate, which in turn causes the lever arm's vertical member to exert a force on the load cell. Consequently, the weight of the storage bag on the lever arm's horizontal pivot point exerts a measurable force on the load cell. This force is analyzed by a processor to provide an extremely accurate measurement of the storage bag's weight, and thus, the weight of the dialysate within the storage bag. Any increase or decrease in the amount of dialysate in the storage bag results in a change in the force exerted on the load cell by the lever arm's vertical member. The processor can detect and measure this change in force to determine whether the dialysate storage bag is adding or removing fluid.

[0024] In a preferred embodiment, the horizontal member of the lever arm extends almost completely horizontally and is therefore perpendicular to gravity. Since the storage bag is suspended from the horizontal member of the lever arm due to gravity, it will extend vertically perpendicular to the horizontal member of the lever arm. In order to ensure that the lever arm is horizontal, or to measure the inclination of the lever arm, the liquid level sensor preferably includes a tilt sensor that is also electrically connected to the processor. A tilt sensor (also known as a tilt switch or a rolling ball sensor) is an instrument for measuring the inclination of an object on multiple axes of a reference plane. The tilt sensor measures the tilt position with reference to gravity and is capable of detecting orientation and / or inclination. Here, the tilt sensor is fixed to the hemodialysis machine to determine whether the hemodialysis machine is tilted, and thus whether its horizontal member is tilted. The tilt sensor can be located anywhere on the machine to determine whether the machine has tilted beyond a predetermined inclination, and more preferably, the tilt sensor determines the amount and direction of the tilt of the hemodialysis machine. In a preferred embodiment, the tilt sensor is located on the lever arm to most accurately measure the inclination of the horizontal member of the lever arm.

[0025] The amount of tilt of the hemodialysis machine (more specifically, the vertical tilt of the storage bag relative to the horizontal member of the lever arm) will change the ability of the load cell to accurately measure the weight of the storage bag. Even a degree or two of tilt can result in an erroneous reading. Therefore, a tilt sensor is provided as a fail-safe device so that if the hemodialysis machine is not level within predetermined parameters, the processor will prevent the dialysis treatment from being performed, or if the machine begins to tilt during a treatment, the treatment is stopped. In another preferred embodiment, the tilt sensor measures the amount of tilt of the horizontal member of the lever arm. In the event that the amount of tilt is below a predetermined level, but the tilt is sufficient to substantially affect the force reading of the load cell, the processor runs an algorithm that combines the tilt measurement to correct the amount of tilt, thereby providing an accurate weight measurement of the storage bag.

[0026] Preferably, the dialysis system includes three main pumps. The first and second "dialysate" pumps are connected to the dialysate flow path for pumping dialysate from the reservoir to the dialyzer and back to the reservoir through the dialysate flow path. Preferably, the first pump is positioned in the dialysate flow path "upstream" (meaning in front of the flow path) of the dialyzer, while the second pump is positioned in the dialysate flow path "downstream" (meaning in the flow path) of the dialyzer. At the same time, the third main pump of the hemodialysis system is connected to the blood flow path. The "blood" pump pumps blood from the patient through the arterial blood line, through the dialyzer and through the venous blood line to return to the patient. Preferably, the third pump is positioned in the blood flow path upstream of the dialyzer.

[0027] The hemodialysis system may also include one or more sorbent filters for removing toxins that permeate from the plasma through the semipermeable membrane into the dialysate. The filter material used in the filter is well known to those skilled in the art. For example, suitable materials include resin beds including zirconium-based resins. Acceptable materials are also described in U.S. Patent No. 8,647,506 and U.S. Patent Publication No. 2014 / 0001112. Other acceptable filter materials can be developed and utilized by those skilled in the art without undue experimentation. Depending on the type of filter material, the filter housing may include a vapor membrane capable of releasing gases such as ammonia.

[0028] In a first embodiment, a filter is connected to the dialysate flow path downstream of the dialyzer to remove toxins from the dialysate before it is returned to the reservoir. In a second embodiment, the filter is external to the closed-loop dialysate flow path, but could instead be located within a separate closed-loop "filter" flow path selectively connected to either of the two dialysate reservoirs. Preferably, the hemodialysis system includes an additional fluid pump for pumping contaminated dialysate through the filter flow path and its filter.

[0029] Preferably, the hemodialysis system includes two additional flow paths in the form of a "drain" flow path and a "fresh dialysate" flow path. The drain flow path includes one or more fluid drain lines for draining a reservoir of contaminated dialysate, and the fresh dialysate flow path includes one or more fluid fill lines for delivering fresh dialysate from a fresh dialysate supply to the reservoir. One or more fluid pumps can be connected to the drain flow path and / or the fresh dialysate flow path to deliver the fluids to their intended destinations.

[0030] In addition, the hemodialysis system includes a plurality of fluid valve assemblies for controlling the flow of blood through the blood flow path, for controlling the flow of dialysate through the dialysate flow path, and for controlling the flow of used dialysate through the filter flow path. The valve assembly can be any type of electromechanical fluid valve structure that can be determined by a person skilled in the art, including but not limited to traditional electromechanical two-way fluid valves and three-way fluid valves. A two-way valve is any type of valve with two ports, including an inlet port and an outlet port, wherein the valve simply allows or hinders the flow of fluid through the fluid path. In contrast, a three-way valve has three ports and is used to close the flow of fluid in one fluid path while opening the flow of fluid in another path. In addition, the valve assembly of the dialysis machine can include a safety pinch valve, such as a pinch valve connected to a venous blood line, for selectively allowing or hindering the flow of blood through the venous blood line. A pinch valve is provided to clamp the venous blood line and thereby prevent blood from flowing back to the patient if an unsafe condition is detected.

[0031] Preferably, the hemodialysis system includes sensors for monitoring hemodialysis. To this end, preferably, the dialysis machine has at least one flow sensor connected to the dialysate flow path for detecting the fluid flow (volume and / or velocity) in the dialysate flow path. In addition, it is preferred that the dialysis machine includes one or more pressure sensors for detecting the pressure in the dialysate flow path, or at least one occlusion sensor for detecting whether the dialysate flow path is blocked. Preferably, the dialysis machine also has one or more sensors for measuring the pressure and / or fluid flow in the blood flow path. The pressure and flow sensors can be separate components, or the pressure and flow measurements can be performed by a single sensor.

[0032] Furthermore, it is preferred that the hemodialysis system include a blood leak detector ("BLD") that monitors the flow of dialysate through the dialysate flow path and detects whether blood has improperly diffused through the dialyzer's semipermeable membrane into the dialysate flow path. In a preferred embodiment, the hemodialysis system includes a blood leak sensor assembly comprising a light source that transmits light through the dialysate flow path and a light sensor that receives the light transmitted through the dialysate flow path. After passing through the dialysate flow path, the received light is subsequently analyzed to determine whether the light has changed to reflect the possible presence of blood in the dialysate.

[0033] The dialysis machine preferably includes additional sensors, including an ammonia sensor and a pH sensor, for detecting the ammonia level and pH value within the dialysate. Preferably, the ammonia sensor and the pH sensor are located immediately downstream of the filter in the dialysate flow path. Furthermore, the dialysis machine has a bubble sensor connected to the arterial blood line and a bubble sensor connected to the venous blood line to detect the formation of bubbles in the blood flow path.

[0034] The hemodialysis system has a processor that contains specialized electronics for controlling the hemodialysis system. The processor contains power management and control circuits connected to the pump motor, valves, and dialysis machine sensors for controlling the correct operation of the hemodialysis system.

[0035] The dialysis machine provides a hemodialysis system that is transportable, lightweight, easy to use, patient-friendly, and capable of being used at home.

[0036] Furthermore, the above-described hemodialysis system provides a great deal of control and monitoring not otherwise provided by hemodialysis systems, thereby providing enhanced patient safety.

[0037] Those skilled in the art will appreciate other features and advantages of the present invention after reading the following detailed description with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 is a flow chart illustrating a first embodiment of a hemodialysis system;

[0039] Figure 2 yes Figure 1 A flow chart illustrating an embodiment in which dialysate bypasses a filter by flowing through a bypass flow path;

[0040] Figure 3 yes Figure 1 Flowchart illustrating an embodiment of dialysate flowing through a filter in a closed-loop dialysate flow path including a first reservoir;

[0041] Figure 4 yes Figure 1 Flowchart illustrating an embodiment of dialysate flowing through a filter in a closed-loop dialysate flow path including a second reservoir;

[0042] Figure 5 is a flow chart illustrating a second embodiment of a hemodialysis system including a closed-loop filter flow path for filtering fluid in a first reservoir;

[0043] Figure 6 It shows Figure 5 a flow chart of a second embodiment of a hemodialysis system shown in , wherein the filter flow path filters fluid in a second reservoir;

[0044] Figure 7 is a side cross-sectional view of a hemodialysis system showing two preferred reservoir level sensors;

[0045] Figure 8 is an exploded view of a preferred reservoir level sensor;

[0046] Figure 9 is a side cross-sectional view of a preferred reservoir level sensor; and

[0047] Figure 10 is a block diagram showing two reservoir level sensors and one tilt sensor connected to a processor of a hemodialysis system. DETAILED DESCRIPTION

[0048] While the present invention can be embodied in various forms, there will be described below a presently preferred embodiment of the invention as shown in the accompanying drawings, it being understood that this disclosure is to be regarded as illustrative of the invention and is not intended to limit the invention to the specific embodiments shown.

[0049] like Figure 1-6 As best shown in FIG, the hemodialysis system includes a blood flow path 53 and a dialysate flow path 54. The hemodialysis system also includes a reusable dialysis machine and disposable components for performing hemodialysis. The blood flow path 53 includes an arterial blood line 1 for connecting to a patient's artery to collect blood from the patient, and a venous blood line 14 for connecting to a patient's vein to return blood to the patient. The arterial blood line 1 and the venous blood line 14 can be of typical construction known to those skilled in the art.

[0050] The blood flow path 53 delivers blood to the patient in a closed loop system by connecting to the arterial blood line 1 and the venous blood line 14, for transporting blood from the patient through the dialyzer 8 and back to the patient. Preferably, the hemodialysis system includes a heparin supply 6 and a heparin pump connected to the blood flow path 1. The heparin pump delivers a small amount of heparin anticoagulant into the bloodstream to reduce the risk of blood clotting in the machine. The heparin pump can be in the form of a linearly actuated syringe pump, or the heparin pump can be a bag connected to a small peristaltic pump or infusion pump.

[0051] The hemodialysis system includes a dialyzer 8 in a dialysate flow path 54, the dialyzer having a construction and design known to those skilled in the art. Preferably, the dialyzer 8 includes a plurality of hollow fibers forming a semipermeable membrane. Suitable dialyzers are available from Fresenius Medical Care, Baxter International, Nipro Medical, and other manufacturers of hollow fiber dialyzers. Both the blood flow path and the dialysate flow path pass through the dialyzer 8, the dialyzer having an inlet for receiving dialysate, an outlet for discharging dialysate, an inlet for receiving blood from the patient, and an outlet for returning blood to the patient. Preferably, the dialysate flows in a direction opposite to the direction of blood flow through the dialysis machine, wherein the dialysate flow path is isolated from the blood flow path by a semipermeable membrane (not shown). As Figure 1-6 As shown in FIG and explained in more detail below, the dialysate flow path 54 transports dialysate in a closed loop system in which dialysate is pumped from the reservoir (17 or 20) to the dialyzer 8 and back to the reservoir (17 or 20). Both the blood flow path 53 and the dialysate flow path 54 pass through the dialyzer 8 but are separated by the dialyzer's semipermeable membrane.

[0052] Preferably, the hemodialysis system includes three main pumps (5, 26 and 33) for pumping blood and dialysate. For the purposes of this article, the term "pump" can refer to a pump actuator that uses suction or pressure to move a fluid, and can also refer to a pump motor for mechanically moving the actuator. Suitable pump actuators can include impellers, pistons, diaphragms, cams of cam pumps, screws of screw pumps, rollers or linear moving fingers of peristaltic pumps, or any other mechanical structure for moving fluids, as can be determined by those skilled in the art. Meanwhile, the pump motor is an electromechanical device for moving the actuator. The motor can be connected to the pump actuator by a shaft or the like. In a preferred embodiment, the dialysate and / or blood flows through a conventional flexible tube, and each pump actuator consists of a peristaltic pump mechanism, wherein each pump actuator includes a rotor, and multiple cams that compress the flexible tube are attached to the outer circumference of the rotor in the form of "rollers", "shoes", "wipers" or "blades". When the rotor rotates, the compressed portion of the tube is squeezed closed (or "blocked"), forcing the fluid to be pumped through the tube. Additionally, when the tube opens to its natural state after passing the cam, fluid is caused to flow through the tube.

[0053] The first and second main pumps (26 and 33) are connected to the dialysate flow path for pumping the dialysate from the reservoir (17 or 20) to the dialyzer 8 and back to the reservoir (17 or 20) through the dialysate flow path. The first pump 26 is connected to the dialysate flow path "upstream" (meaning in front of the flow path) of the dialyzer 8, while the second pump 33 is connected to the dialysate flow path "downstream" (meaning in the flow path) of the dialyzer 8. At the same time, the third main pump 6 of the hemodialysis system is connected to the blood flow path. The third pump 6 (also referred to as the blood pump) pumps blood from the patient through the arterial blood line, through the dialyzer 8, and through the venous blood line to return to the patient. It is preferred that the third pump 6 is connected to the blood flow path upstream of the dialyzer. The hemodialysis system can include more or less than three main pumps. For example, the dialysate can be pumped through the dialyzer 8 using only a single pump. However, it is preferred that the hemodialysis system comprises two pumps, including a first pump 26 upstream of the dialyzer 8 and a second pump 33 downstream of the dialyzer 8 .

[0054] Preferably, the hemodialysis system includes two or more reservoirs (17 and 20) for storing dialysate solution. The two reservoirs (17 and 20) can be connected to the dialysate flow path 54 at the same time to form a large dialysate source. However, this is not considered preferred. Instead, the hemodialysis system includes a valve assembly 21 for introducing either, but not both, of the two reservoirs (17 or 20) into the dialysate flow path 54 to form a closed-loop system for transporting dialysate from one of the two reservoirs to the dialyzer and back to that reservoir. After the dialysate in the first reservoir 17 has been used, is no longer sufficiently clean, or does not have the appropriate chemical properties, the valve 21 of the hemodialysis system is controlled to remove the first reservoir 17 from the dialysate flow path and replace the second reservoir 20 with fresh dialysate 75 in the dialysate flow path. Therefore, when one reservoir has contaminated dialysate 76 and needs to be emptied and refilled with newly generated dialysate 75, the other reservoir can be used to continue dialysis treatment.

[0055] In this manner, the hemodialysis system can switch between each reservoir 17 and 20 multiple times during treatment. Furthermore, the presence of two reservoirs, as opposed to one reservoir, allows flow to be measured for pump calibration or ultrafiltration measurements while isolating the other reservoir while it is drained or filled. While the reservoirs can be any size desired by the clinician for adequate hemodialysis treatment, preferred reservoirs have a volume between 0.5 liters and 5.0 liters.

[0056] The hemodialysis system also includes an adsorbent filter (also referred to herein as a "filter") connected to the dialysate flow path 54 for removing toxins that permeate from the plasma through the semipermeable membrane into the dialysate. In a first embodiment, the filter 36 is connected to the dialysate flow path 54 downstream of the dialyzer to remove toxins transferred to the dialysate by the dialyzer before the dialysate is transported to the reservoir. Filter materials for dialysis machines are well known to those skilled in the art. For example, suitable materials include resin beds including zirconium-based resins. Preferably, the filter has a housing including a zirconium oxide layer, a zirconium phosphate layer, and a carbon layer. Acceptable materials are described in U.S. Patent No. 8,647,506 and U.S. Patent Gazette No. 2014 / 0001112. Those skilled in the art can develop and utilize other acceptable filter materials without undue experimentation. The filter housing may or may not include a vapor membrane capable of releasing gas, including ammonia but not liquid, particularly not including the dialysate flowing through the filter.

[0057] In the case of a hemodialysis system with an adsorbent filter, the dialysis flow path 54 preferably includes a safety feature in the form of an ammonium sensor 37 and a pH sensor 38 located immediately downstream of the adsorbent cartridge 36. When the adsorbent filter (36) is exhausted, the filter 36 may begin to release ammonium ions due to a filtration chemical reaction. At a certain level, the ammonium ions in the dialysate can harm the patient. Preferably, the ammonium ion sensor 37 measures the amount of ammonium ions in parts per million (ppm). When the measured value reaches a range of approximately 5 to 20 ppm, a warning state is activated and treatment with the dialysate is stopped. The dialysate can be drained and dialysis treatment can be continued with fresh dialysate by using an alternative reservoir. Similarly, the pH sensor 38 also serves as a safety feature and supports the measurement of ammonium ions. As the pH value of the dialysate changes, the equilibrium state of ammonia (NH3) and ammonium ions (NH4+) changes. If the pH value of the dialysate is measured outside the range of approximately 6.4 to 7.0 pH, a warning state can be activated and the dialysate in use can be drained.

[0058] It is also preferred that the hemodialysis system has a reagent bag 39 and a pump 40 for introducing reagent into the dialysate flow path 54 immediately after the sorbent filter 36. The reagent bag (39) contains a concentrated solution of salts and ions for re-infusing the filtered dialysate. By filtering waste, the sorbent filter (36) also removes beneficial ions, such as calcium and salts, from the dialysate. Before the filtered dialysate can be recirculated, calcium and salts must be re-infused so that the dialysate does not absorb these beneficial ions from the patient's blood. Preferably, the reagent bag 39 will hold 1 to 3 liters of concentrated reagent. The reagent pump 40 can be any type of pump, such as a peristaltic pump or a diaphragm pump. To ensure that the hemodialysis system introduces the appropriate amount of salts and ions into the dialysate, a conductivity sensor 41 can be positioned in the dialysate flow path 54 immediately after the reagent bag 39. The conductivity sensor 41 serves as a safety feature, measuring the total dissolved solids of the regenerated dialysate. In the event that the total dissolved solids are detected to be outside the specified range, the operation of the pump 40 can be increased or decreased, or alternatively, the treatment can be stopped entirely. For example, if a fault condition is detected in the dialysate, the fluid can be redirected through the bypass path 30 by the three-way valves 29 and 32 so that the dialysate does not meet the patient's blood in the dialyzer. More specifically, the three-way valve 29 directs the dialysate to the inlet of the dialyzer, and the three-way valve 32 directs the dialysate back from the dialysate outlet through the dialysate flow path 54. However, if a fault condition is detected in the dialysate, such as if too low a temperature or too many ammonium ions are detected in the dialysate, the dialysate is redirected by the three-way valves 29 and 32 to bypass the dialyzer 8 through the bypass path 30.

[0059] for Figure 1-4In the embodiment shown in FIG, the hemodialysis system includes a drain flow path 55 for disposing of spent dialysate from the reservoirs (17 and 20). Figure 1-4 In the embodiment shown, the drain flow path 55 is connected to both reservoirs (17 and 20). The spent dialysate can be drained via the drain flow path 5 by gravity feed, or the hemodialysis system can include any type of pump 44 selected by one skilled in the art to pump the spent dialysate to be discarded, such as to a conventional building sewage line 45.

[0060] for Figure 1-4 In the embodiment shown, the hemodialysis system preferably includes a dialysate source 46 to replenish each reservoir 17 and 20. Preferably, the dialysate source includes a clean water source 46 mixed with reagents (48 and 50) to provide a dialysate with the desired properties. In a preferred embodiment, the clean water source 46 is provided by a reverse osmosis ("RO") machine located near the device, which produces clean water and then adds chemical concentrates to produce dialysate. The fluid is supplied to the reservoirs (17 and 20) via a "fresh dialysate" flow path 56. Preferably, the hemodialysis system also includes a concentrated reagent source (48 and 50) that can be stored in a disposable bag. Preferably, the concentrated reagent contains one or more of the following: bicarbonate solution, acid solution, lactate solution, saline solution. It is necessary to divide some reagents into two bags (48 and 50) to prevent undesirable interactions or solute precipitation. The concentrated reagent source (48 and 50) is connected to the supply line 46 by a pump (47 and 49). Activation of the pumps (47 and 49) introduces a concentrated reagent into the water source to provide dialysate to the reservoirs (17 and 20).

[0061] As an alternative to using dialyzer 8, the hemodialysis system includes an auxiliary "bypass" flow path 35 that selectively routes dialysate around a sorbent filter 36. The bypass flow path includes a three-way valve 34 upstream of the filter. The three-way valve 34 is switched to direct the dialysate through the sorbent filter 36, or alternatively, the three-way valve 34 is switched to direct the dialysate through the bypass flow path 35 to avoid the sorbent filter 36. For example, if the sorbent filter is unavailable, if the sorbent filter is exhausted, or if a sorbent filter is not required for a particular patient treatment, the three-way valve 34 is switched to direct the dialysate along the bypass flow path 35.

[0062] exist Figure 5 and Figure 6In the alternative embodiment shown, the sorbent filter 71 is located outside the closed-loop dialysate flow path. The hemodialysis system includes a separate closed-loop "filter" flow path 57 selectively connected to either of the two dialysate reservoirs 17 or 20, and the filter 71 is positioned in series in the closed-loop filter flow path 57. The dialysis machine includes an additional fluid pump 58 for pumping contaminated dialysate through the filter flow path and the filter 71. Figure 5 and 6 As shown in FIG, the preferred filter flow path 57 includes a three-way valve 43 that determines which reservoir drains the contaminated dialysate. For example, Figure 5 Three-way valve 43 is shown connecting reservoir 20 to filter flow path 57 instead of reservoir 17 . Figure 6 The three-way valve 43 is shown connecting reservoir 17, rather than reservoir 20, to the filter flow path 57. The filter flow path may include a pump 58, or the dialysate may be gravity-fed to dispense contaminated dialysate from reservoirs 17 or 20. Additionally, the filter flow path 57 preferably includes a pressure sensor 59, a check valve 60, an ammonium sensor 69, and a pH sensor 70.

[0063] This embodiment of the hemodialysis machine includes a system for introducing reagents into the filter flow path. Figure 5 and Figure 6 As shown in FIG, the filter flow path 57 includes a first reagent source 61 containing salt and a second reagent source 65 containing bicarbonate and lactic acid solution. These reagents are introduced into the filter flow path using pumps 62 and 66 and mixers 63 and 67. Preferably, the filter flow path also has a safety feature in the form of an ammonium sensor 69 to ensure that the filter 71 does not become depleted and introduce unacceptable ammonium ions into the dialysate, as well as conductivity sensors 64 and 68 that monitor whether the reagents have been properly introduced into the clean dialysate to provide the appropriate amount of beneficial ions. Finally, the filter flow path 57 includes a pair of check valves 51 and 52 that are opened or closed to ensure that the now clean dialysate returns to the reservoir from which the contaminated dialysate has been drained.

[0064] Still refer to Figure 1-6 The hemodialysis system preferably has a heater 23 thermally coupled to the dialysate flow path or reservoir for heating the dialysate to a desired temperature. Figure 1-6In the embodiment shown, a single heater 23 is thermally coupled to the dialysate flow path downstream of the two reservoirs (17 and 20). However, the hemodialysis system may include additional heaters, and one or more heaters may be located in different locations. For example, in an alternative embodiment, the hemodialysis system includes two heaters, with a single heater thermally coupled to each reservoir. The one or more heaters are preferably electrically activated and include a resistor that generates heat as an electric current passes through it.

[0065] In addition, the hemodialysis system has various sensors for monitoring hemodialysis, in particular for monitoring the dialysate flow path and the blood flow path. To this end, the hemodialysis system preferably has one or more flow sensors 25 connected to the dialysate flow path for monitoring the fluid flow (volume and / or velocity) in the dialysate flow path. In addition, it is preferred that the hemodialysis system includes one or more pressure or occlusion sensors (9 and 27) for detecting the pressure in the dialysate flow path. Preferably, the hemodialysis system also has one or more sensors for measuring the pressure (4 and 7) and / or fluid flow 11 in the blood flow path.

[0066] Preferably, the hemodialysis system includes temperature sensors (22, 24, and 28) for measuring the temperature of the dialysate throughout the dialysate flow path. In addition, the hemodialysis system has a level sensor for detecting the level of the fluid in the reservoir (17 and 20). Preferred level sensors may include capacitive fluid level sensors (15 and 18), ultrasonic fluid level sensors, or load cells (16 and 19), such as those described in U.S. Patent No. 9,649,419.

[0067] like Figure 7-10 As shown in FIG, the weight of each reservoir 17 and 20 and the level of the dialysate are measured by a preferred level sensor (16 or 19) having a lever arm 80, a load cell 90 and a tilt sensor 78. Figure 10 As shown in FIG, a load cell 90 and a tilt sensor 78 are electrically connected to a processor 77 for sending force and tilt measurements to the processor. A lever arm 80 has a horizontal member 81 and a vertical member 83. In addition, the lever arm 80 is pivotally attached to the housing 79 of the hemodialysis machine at or at least near the location where the horizontal member 81 of the lever arm joins the vertical member 83 of the lever arm. The lever arm can be pivotally attached to the housing of the machine using any pivoting configuration that can be determined by one skilled in the art. However, in Figure 7-9 In the preferred embodiment shown, pivoting of the lever arm relative to the machine housing is achieved by the housing 79 having a recess 91 and the lever arm 80 having a pivot pin 92 which rests within the recess and pivots therein.

[0068] The reservoir (17 or 20) is preferably a commonly sold dialysate bag having a hole at its upper end that holds 1-5 liters of dialysate. In order to secure the dialysate bag (17 or 20) to the horizontal member 81 of the lever arm, the distal end of the horizontal member has a rod, shaft, or hook for receiving the hole of the storage bag. Also preferably, the horizontal member 81 has an abutment 93 for holding the reservoir at a predetermined horizontal distance 82 from the pivot point 58 of the lever arm. Reference Figure 9 The distal end of the horizontal member may be beveled or grooved to hold the dialysate bag against the abutment 93 .

[0069] The vertical member 83 of the lever arm extends downwardly adjacent to the housing 79 of the hemodialysis machine. Simultaneously, a load cell 90 of the reservoir level sensor is secured to the hemodialysis machine adjacent to the vertical member 83 of the lever arm. Because the lever arm 80 is pivotally secured at a pivot point 85, any weight on the horizontal member 81 of the lever arm causes the lever arm 80 to rotate, which in turn causes the vertical member 83 of the lever arm to apply a force to the load cell 90.

[0070] like Figure 9 As shown in FIG, the amount of force applied by the lever arm's vertical member 83 to the load cell 90 depends on the distance 82 between the pivot point 85 and the storage bag 17, and on the distance 84 between the pivot point 85 and the location where the vertical member 83 engages the load cell 90. More specifically, the ratio of these two dimensions determines how much leverage the vertical member 83 exerts on the load cell 90. In a first embodiment, the dimensions are identical. Specifically, in a preferred embodiment, the distance 82 between the pivot point 85 and the storage bag (17 or 20) is 40 mm, and the distance 84 between the pivot point 85 and the location where the vertical member 83 engages the load cell 90 is 40 mm. Assuming that the horizontal member 81 is substantially horizontal and that there are negligible friction effects, the force exerted by the vertical member 83 will be the same as the weight of the storage bag 17 containing the dialysate 75. In alternative embodiments, the distance 82 between the pivot point 85 and the storage bag 17 is greater or less than the distance 84 between the pivot point 85 and the location where the vertical member 83 engages the load cell 90. Due to the increase or decrease in leverage applied by lever arm 80, this will result in a force reading by load cell 90 that is different from the weight of storage bag 17. However, processor 77 can convert the load cell measurement to provide an accurate determination of the weight of storage bag 17. For a variety of reasons, including engineering space requirements, consideration of the load cell's measurement range, and / or the load cell's sensitivity, it may be desirable to increase or decrease the ratio of horizontal member length to vertical member length, thereby increasing or decreasing the leverage of lever arm 80.

[0071] In order to correctly measure the dialysate reservoir, it is important to keep the horizontal member of the lever arm almost perfectly horizontal and, therefore, perpendicular to gravity. Any deviation from horizontal will change the force applied to the load cell 90, since the weight of the reservoir (17 or 20) on the horizontal member 81 will no longer be perpendicular to the horizontal member. To overcome this problem, the hemodialysis system preferably includes a tilt sensor 78 connected to the processor 77, such as Figure 10 The tilt sensor 78 can be located anywhere on the hemodialysis machine. However, in order to accurately measure any tilt of the horizontal member 81, it is preferred that the tilt sensor 78 be located on or adjacent to the horizontal member.

[0072] The measurement from tilt sensor 78 is transmitted to processor 79. If the machine's tilt is too great to provide safe dialysis treatment, the processor may disable the dialysis machine. Alternatively, in situations where the machine's tilt significantly alters the weight measurement but does not significantly compromise patient safety, processor 78 may execute an algorithm incorporating relatively simple geometric equations to correct for the machine's tilt, thereby providing an accurate weight measurement of the reservoir bag. Those skilled in the art can develop algorithms and equations for correcting the reservoir bag's weight measurement without undue experimentation.

[0073] like Figure 8 As shown in FIG, the vertical member is preferably engaged and secured to the load cell by a threaded fastener 86. In the preferred embodiment shown, the vertical member 83 includes a female threaded insert 87, and the load cell 90 has a female threaded socket 88 that is mechanically connected by the male threaded fastener 86. Any increase or decrease in the amount of dialysate in the storage bag causes the vertical member 83 of the lever arm to increase or decrease the force acting on the load cell via the male threaded fastener 86. This force and changes in force are transmitted to a processor that determines the amount of dialysate within the reservoir (17 or 20) and whether the dialysate reservoir is gaining or losing fluid.

[0074] Furthermore, it is preferred that the hemodialysis system includes a blood leak detector 31 that monitors the flow of dialysate through the dialysate flow path and detects whether blood improperly diffuses through the semipermeable membrane of the dialyzer into the dialysate flow path.

[0075] Preferably, the hemodialysis system also includes a first pinch valve 2 connected to the arterial blood line 1 for selectively allowing or blocking blood flow through the arterial blood line, and a second pinch valve 13 connected to the venous blood line 14 for selectively allowing or blocking blood flow through the venous blood line. The pinch valves are provided to clamp the arterial blood line 1 and the venous blood line 14 to prevent blood from flowing back into the patient if any sensor detects an unsafe condition. Providing an additional safety feature, the hemodialysis system includes blood line bubble sensors (3 and 12) to detect whether bubbles are traveling backward along the arterial line (blood leak sensor 3) or the venous line (blood leak sensor 12). Furthermore, the blood flow path 53 may include a bubble trap 10 comprising a pressurized air bag within a plastic housing. Bubbles rise to the top of the bubble trap while blood continues to flow toward the trap's lower outlet. This component reduces the risk of bubbles entering the patient's blood.

[0076] In order to control the flow and direction of blood and dialysate by the hemodialysis system, the hemodialysis system includes various fluid valves for controlling the flow of fluid by the various flow paths of the hemodialysis system. Various valves include pinch valves and two-way valves that must be opened or closed, and three-way valves that allow dialysate to be transferred as expected by the required flow path. In addition to the above-mentioned valves, the hemodialysis system also includes a three-way valve 21 at the outlet of the reservoir, which determines from which reservoir (17 or 20) the dialysate passes through the dialyzer 8. Additional three-way valve 42 determines to which reservoir the used dialysate is sent. Finally, two-way valves 51 and 52 (which can be pinch valves) are located at the inlet of the reservoir to allow or hinder the supply of fresh dialysate to the reservoir (17 and 20). Of course, those skilled in the art can determine that alternative valves can be used, and the present invention is not intended to limit the specific two-way valve or three-way valve determined.

[0077] Although not shown in the figures, the hemodialysis system includes a processor and a user interface. The processor contains dedicated electronic components for controlling the hemodialysis system, including power management circuits connected to the pump motor, sensors, valves and heaters for controlling the correct operation of the hemodialysis system. The processor monitors each of the various sensors to ensure that the hemodialysis treatment is performed according to the pre-programmed program input by the medical staff into the user interface. The processor can be a general-purpose computer or a microprocessor, including hardware and software that can be determined by those skilled in the art to monitor the various sensors and provide automatic or directional control of the heater, pump and pinch valve. The processor can be located within the electronics of the circuit board or within the aggregate processing of multiple circuit boards.

[0078] Also not shown, the hemodialysis system includes a power supply for providing power to the processor, user interface, pump motor, valves, and sensors. The processor is connected to the dialyzer sensors (including reservoir level sensors (15, 16, 18, and 19), blood leak sensor 31, ammonia sensor 37, pressure and flow sensors (4, 7, 9, 11, 25, and 27), temperature sensors (22, 24, and 28), blood line bubble sensors (3 and 12), pumps (5, 6, 26, 33, 40, 44, 47, and 49), and pinch valves (2 and 13) via conventional circuitry.

[0079] In operation, the processor is electrically connected to the first, second and third main pumps (5, 26 and 33) for controlling the activation and rotational speed of the pump motors, and then controlling the pump actuators, and then controlling the pressure and fluid velocity of the blood through the blood flow path and the pressure and fluid velocity of the dialysate through the dialysate flow path. By independently controlling the operation of the dialysate pumps 26 and 33, the processor can maintain, increase or decrease the pressure and / or fluid flow in the dialysate flow path in the dialyzer. In addition, by independently controlling all three pumps, the processor can control the pressure difference across the semipermeable membrane of the dialyzer to maintain a predetermined pressure difference (zero, positive or negative), or maintain a predetermined pressure range. For example, most hemodialysis is performed when the pressure difference across the semipermeable membrane is zero or close to zero, and for this reason, the processor can monitor and control the pump to maintain this required zero or close to zero pressure difference. Alternatively, the processor can monitor the pressure sensor and control the pump motor, and then control the pump actuator to increase and maintain the positive pressure in the blood flow path in the dialyzer relative to the pressure of the dialysate flow path in the dialyzer. Advantageously, this pressure differential can be affected by the processor to provide ultrafiltration and transfer of free water and dissolved solutes from the blood to the dialysate.

[0080] In a preferred embodiment, the processor monitors blood flow sensor 11 to control blood pump flow. It uses dialysate flow sensor 25 to control dialysate flow from the upstream dialysate pump. The processor then uses reservoir level sensors (15, 16, 18, and 19) to control flow from the downstream dialysate pump 33. Changes in the fluid level (or volume) in the dialysate reservoir are the same as changes in the patient's volume. By monitoring and controlling the fluid level in the reservoir, forward, reverse, or zero ultrafiltration can be achieved.

[0081] In addition, the processor monitors all of the various sensors to ensure the hemodialysis machine is operating efficiently and safely. If an unsafe or unspecified condition is detected, the processor corrects the defect or halts further hemodialysis treatment. For example, if the venous blood line pressure sensor 9 indicates an unsafe pressure or the bubble sensor 12 detects an air bubble in the venous blood line, the processor issues an alarm, disables the pump, and closes the pinch valve to prevent further blood from flowing back into the patient. Similarly, if the blood leak sensor 31 detects that blood has penetrated the dialyzer's semipermeable membrane, the processor issues an alarm and halts further hemodialysis treatment.

[0082] The user interface of the dialysis machine may include a keyboard or touch screen (not shown) for enabling the patient or medical staff to enter commands regarding treatment or to enable the patient or medical staff to monitor the performance of the hemodialysis system. In addition, the processor may include a Wi-Fi or Bluetooth connection for transmitting information or control to a remote location.

[0083] The various components of the preferred hemodialysis machine will be identified hereinafter by numbers corresponding to the components shown in the figures.

[0084]

[0085]

[0086]

[0087]

[0088] Treatment options

[0089] The hemodialysis system provides increased flexibility in treatment options depending on the desired dialysis frequency, the patient's characteristics, the availability of dialysate or water, and the desired portability of the dialysis machine. For all treatments, the blood flow path 53 delivers blood to the patient in a closed loop system by connecting to the arterial blood line 1 and the venous blood line 14 for transporting blood from the patient to the dialyzer and back to the patient.

[0090] refer to Figure 2The first method of using a hemodialysis system does not require the use of an adsorbent filter 36. Water is introduced into the machine via a fresh dialysate flow path 56 from a water source 46, such as a reverse osmosis (RO) supply. If necessary, chemical concentrates 48 and 50 are added to the clean water using chemical concentrate pumps 47 and 49. The mixed dialysate is then introduced into reservoirs 17 and 20. For this process, dialysate 75 from the first reservoir is recirculated through the dialyzer 8 via a bypass path 35 back to the same reservoir. When the volume of the reservoir has been recycled once, the reservoir is emptied via the drain flow path 55 and refilled via the fresh dialysate flow path 56.

[0091] Simultaneously, as the first reservoir is emptied and refilled, the hemodialysis treatment continues using the second reservoir (17 or 20). Figure 2 As shown in FIG, once the processor determines that all the dialysate has been recycled once, or determines that the dialysate is contaminated, the processor switches all relevant valves (21, 42, 43, 51, and 52) to remove the first reservoir 20 from the patient treatment and insert the second reservoir 17 into the dialysate flow path 54. The dialysate from the second reservoir 17 is recycled through the dialyzer 8 via the bypass path 35 and returned to the same reservoir 17. This switching back and forth between the reservoirs 17 and 20 continues until the dialysis treatment is completed. This operation is similar to but different from a conventional single-pass system in that no sorbent filter is used.

[0092] exist Figure 3 In the second embodiment shown, the sorbent cartridge 36 filters the dialysate after it passes through the dialyzer 8. To do this, the processor switches the three-way valve 34 to incorporate the sorbent cartridge 36 into the dialysate flow path 54, and the processor switches the various valve assemblies (21, 42, 43, 51, and 52) to utilize the reservoir 17 during the dialysis treatment. Clean dialysate 75 is recirculated through the dialyzer 8 and the sorbent cartridge 36, and then the dialysate is returned to the same reservoir 17 via the dialysate flow path 54. This recirculation continues for reasons determined by the processor, including but not limited to, that the sorbent cartridge has been depleted, that the dialysate has become contaminated, or that ultrafiltration has caused the reservoir 17 to become full and needs to be emptied and refilled. Meanwhile, in the event that the fluid in the reservoir 20 is contaminated, it is drained through the drain flow path 45, and the reservoir 20 is then refilled using the fresh dialysate flow path 56.

[0093] like Figure 4As shown, once the processor determines that it is not appropriate to continue using reservoir 17 for dialysis treatment, the processor switches the various valve assemblies (21, 42, 43, 51, and 52) to remove reservoir 17 from the dialysate flow path 54 and instead insert reservoir 20 into the dialysis flow path for dialysis treatment. Clean dialysate 75 is recirculated back to the same reservoir 20 through the dialyzer 8 and the sorbent filter 36. Similarly, this recirculation continues using reservoir 20, as determined by the processor, until switching back to reservoir 17 or until the dialysis treatment is completed. While the dialysis treatment continues using reservoir 20, the contaminated fluid 76 in reservoir 17 is drained through the drain flow path. Thereafter, reservoir 17 is refilled using fresh dialysate flow path 56. Similar to other treatment methods, this switching back and forth between reservoirs 17 and 20 continues until the dialysis treatment is completed.

[0094] exist Figure 5 and Figure 6 In another embodiment shown, hemodialysis treatment is performed with Figure 2 , wherein the sorbent filter 36 is not used in the dialysate flow path 54. Although a filter 36 could be used in the dialysate flow path 54, for this embodiment, it is preferred that the dialysate 75 be directed through the bypass path 35 so as to avoid the sorbent filter 36. During treatment, the dialysate 75 from the first reservoir is recirculated through the dialyzer 8 via the bypass path 35 and directed back to the same reservoir. More preferably for this embodiment, the hemodialysis system does not include a sorbent filter 36. Instead, reference is made to Figure 5 and 6 , the hemodialysis system includes a single sorbent filter 71 located within a separate closed-loop flow path referred to herein as filter flow path 57. Although Figure 5 and 6 A hemodialysis system is shown that includes two sorbent filters 36 and 71 , but the sorbent filter 36 within the dialysate flow path 54 is optional and need not be incorporated in this embodiment of the hemodialysis system.

[0095] Similar to the previous embodiment, dialysis treatment is performed while switching back and forth between reservoirs 17 and 20. Figure 5When a dialysis treatment uses clean dialysate 75 in reservoir 17, the various valve assemblies (21, 42, 43, 51, and 52) are switched to insert the second reservoir 20 into the closed-loop filter flow path 57. Contaminated water 76 is drained from reservoir 20 via pump 58 and pressure sensor 59. Thereafter, the contaminated water 76 is filtered through sorbent filter 71. Reagents 61 and 65 can be introduced into the filter flow path using gravity feed or pumps 62 and 66. The reagents are mixed within mixers 63 and 67 before the now clean dialysate is tested for compliance by conductivity testers 64 and 68, ammonium sensor 69, and pH sensor 70. If the tests indicate that the water is now clean, it is directed back to reservoir 20.

[0096] refer to Figure 6 , the processor continues to monitor the outputs of various sensors, including those within the dialysate flow path 54. Once the water within reservoir 17 becomes contaminated, it is removed from the dialysate flow path and reservoir 20 is replaced in its place by again switching all relevant valve assemblies (21, 42, 43, 51, and 52). Dialysate 75 from the second reservoir 20 is recirculated through the dialyzer 8 in the closed-loop dialysate flow path 54 and directed back to the same reservoir. Simultaneously, the now contaminated water 76 in reservoir 17 is drained by pump 58 and pressure sensor 59 before being filtered through sorbent filter 71. Again, reagents 61 and 65 can be introduced into the filter flow path 57, where they are mixed within mixers 63 and 67. Before filling reservoir 17, the now clean dialysate is tested for compliance by conductivity testers 64 and 68, ammonium sensor 69, and pH sensor 70. This process of alternating reservoirs continues until the prescribed hemodialysis treatment is completed or a fault is detected that requires stopping treatment.

[0097] Finally, with respect to the exemplary embodiments of the present invention as shown and described herein, it should be appreciated that a hemodialysis system is disclosed. The principles of the present invention can be implemented in a variety of configurations beyond those shown and described, and it should be understood that the present invention is not subject to any limitation of the exemplary embodiments, but rather relates generally to hemodialysis systems and can take various forms to do so without departing from the spirit and scope of the present invention. Those skilled in the art will also appreciate that the present invention is not limited to the specific geometries and materials of the disclosed constructions, but may require other functionally equivalent structures or materials now known or later developed without departing from the spirit and scope of the present invention. Furthermore, the various features of each of the above-described embodiments can be combined in any logical manner and are intended to be included within the scope of the present invention.

[0098] The grouping of alternative embodiments, elements, or steps of the present invention should not be construed as limiting. Each group member may be referred to and claimed individually or in any combination with other group members disclosed herein. For reasons of convenience and / or patentability, it is contemplated that one or more members of a group may be included in or deleted from a group. When any such inclusion or deletion occurs, the specification is deemed to contain the group as modified.

[0099] Unless otherwise stated, all numbers used in this specification and claims to represent characteristics, items, quantities, parameters, properties, terms, etc. should be understood to be modified by the term "about" in all cases. As used herein, the term "about" means that the characteristic, item, quantity, parameter, property or term so defined is included in a range of plus or minus ten percent above and below the value of the characteristic, item, quantity, parameter, property or term. Therefore, unless otherwise stated, the numerical parameters listed in the specification and the appended claims are approximate values ​​that may vary. At least, rather than attempting to limit the application of the doctrine of equivalents to the scope of the claims, each numerical indication should at least be interpreted based on the number of reported significant figures and by applying ordinary rounding methods. Although the numerical ranges and values ​​illustrating the broad scope of the present invention are approximate, the numerical ranges and values ​​illustrated in the specific examples are reported as accurately as possible. However, any numerical range or value inherently contains certain errors, which are necessarily caused by the standard deviation found in their respective test measurements. The enumeration of numerical ranges herein is intended only to be used as a shorthand method for individually citing each individual value falling within the range. Unless otherwise indicated herein, each individual value of a numerical range is incorporated into the specification as if it were individually recited herein.

[0100] The terms "a," "an," "the," and similar references used in the context of describing the invention (especially in the context of the following claims) should be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. All methods described herein can be performed in any suitable order, unless otherwise indicated herein or clearly contradicted by context. The use of any and all examples or exemplary language (e.g., "such as") provided herein is intended merely to better illuminate the invention and does not limit the scope of the invention otherwise claimed. No language in this specification should be construed to indicate any non-claimed element as essential to the practice of the invention.

[0101] The specific embodiments disclosed herein may be further limited in the claims using the language consisting of or consisting essentially of. When used in a claim, whether as filed or added by amendment, the transition term "consisting essentially of" excludes any elements, steps, or ingredients not specified in the claim. The transition term "consisting essentially of" limits the scope of the claim to the specified materials or steps, and those that do not materially affect the basic and novel characteristics. The embodiments of the invention so claimed are inherently or expressly described and enabled herein.

[0102] It should be understood that the order in which the logic code, programs, modules, processes, methods, and the corresponding elements of each method are executed is purely exemplary. Depending on the implementation, they can be executed in any order or in parallel unless otherwise specified in this disclosure. In addition, the logic code is not related to or limited to any specific programming language and can include one or more modules executed on one or more processors in a distributed, non-distributed, or multi-processing environment.

[0103] While several particular forms of the present invention have been shown and described, it will be apparent that various modifications may be made without departing from the spirit and scope of the invention. The present invention is not intended to be limited, therefore, except as in the following claims. We claim the following.

Claims

1. A hemodialysis system having a reservoir level sensor, comprising: Machine housing; an arterial blood line for connection to an artery of a patient to collect blood from the patient; a venous blood line for connection to a patient's vein to return blood to the patient; dialyzer; a blood flow path connected to the arterial blood line and the venous blood line for conveying blood from the patient to the dialyzer and back to the patient; a reservoir for storing dialysate; a dialysate flow path isolated from the blood flow path, the dialysate flow path connected to the reservoir and the dialyzer for conveying dialysate from the reservoir to the dialyzer; a first pump for pumping dialysate through the dialysate flow path; a second pump for pumping blood through the blood flow path; a filter connected to the dialysate flow path for removing uremic toxins from the dialysate; a reservoir level sensor for measuring the level of dialysate in the reservoir, the reservoir level sensor comprising a lever arm pivotally secured to the machine housing at a pivot point, the lever arm comprising a horizontal member cantilevered horizontally from the pivot point and a vertical member extending vertically from the pivot point, the reservoir being positioned so as to be suspended from the horizontal member, the weight of the reservoir and the dialysate within the reservoir exerting a downward force on the horizontal member, the reservoir level sensor further comprising a load cell for generating an electrical level sensor signal, the load cell being secured to the machine housing and positioned so as to engage the vertical member, such that the downward force exerted on the horizontal member of the lever arm by the weight of the reservoir and the dialysate causes the lever arm to rotate at the pivot point and causes the vertical member of the lever arm to exert a force on the load cell to generate the electrical level sensor signal; as well as A processor is coupled to the load cell of the reservoir level sensor for processing the level sensor electrical signal to determine the level of dialysate in the reservoir.

2. A hemodialysis system with a reservoir level sensor according to claim 1, wherein the processor disables the hemodialysis system if the reservoir level sensor detects that the level of dialysate in the reservoir is below a predetermined threshold.

3. The hemodialysis system having a reservoir level sensor according to claim 1, wherein the reservoir is a flexible bag having a volume between 0.5 liters and 5.0 liters, and the bag includes a hole for receiving the receiving portion of the horizontal member of the lever arm.

4. The hemodialysis system of claim 1 , further comprising a tilt sensor that measures the tilt of the machine housing to produce a tilt measurement, the tilt sensor being connected to the processor, wherein if the processor detects that the machine housing has tilted beyond a predetermined inclination, the processor disables the hemodialysis system.

5. The hemodialysis system of claim 1 , further comprising a tilt sensor that measures the tilt of the machine housing to produce a tilt measurement, the tilt sensor being coupled to the processor, wherein the processor combines the tilt measurement to determine the level of dialysate in the reservoir.

6. A hemodialysis system comprising: Machine housing; an arterial blood line for connection to an artery of a patient to collect blood from the patient; a venous blood line for connection to a patient's vein to return blood to the patient; dialyzer; a blood flow path connected to the arterial blood line and the venous blood line for conveying blood from the patient to the dialyzer and back to the patient; a first reservoir for storing dialysate and a second reservoir for storing dialysate; a dialysate flow path isolated from the blood flow path, the dialysate flow path connected to the reservoir and the dialyzer for conveying dialysate from the reservoir to the dialyzer; a first pump for pumping dialysate through the dialysate flow path; a second pump for pumping blood through the blood flow path; a filter connected to the dialysate flow path for removing uremic toxins from the dialysate; a first reservoir level sensor for measuring the level of dialysate in the first reservoir, the first reservoir level sensor comprising a lever arm pivotally secured to the machine housing at a pivot point, the lever arm comprising a horizontal member cantilevered horizontally from the pivot point and a vertical member extending vertically from the pivot point, the first reservoir being positioned so as to be suspended from the horizontal member, the weight of the first reservoir and the dialysate within the first reservoir exerting a downward force on the horizontal member, the first reservoir level sensor further comprising a load cell for generating a first level sensor electrical signal, the load cell being secured to the machine housing and positioned to engage the vertical member such that a downward force exerted on the horizontal member of the lever arm by the weight of the first reservoir and the dialysate causes the lever arm to rotate at the pivot point and causes the vertical member of the lever arm to exert a force on the load cell to generate the first level sensor electrical signal; a second reservoir level sensor for measuring the level of dialysate in the second reservoir, the second reservoir level sensor comprising a lever arm pivotally secured to the machine housing at a pivot point, the lever arm comprising a horizontal member cantilevered horizontally from the pivot point and a vertical member extending vertically from the pivot point, the second reservoir being positioned so as to be suspended from the horizontal member, the weight of the second reservoir and the dialysate within the second reservoir exerting a downward force on the horizontal member, the second reservoir level sensor further comprising a load cell for generating a second level sensor electrical signal, the load cell being secured to the machine housing and positioned so as to engage the vertical member, such that a downward force exerted on the horizontal member of the lever arm by the weight of the second reservoir and the dialysate causes the lever arm to rotate at the pivot point and causes the vertical member of the lever arm to exert a force on the load cell to generate the second level sensor electrical signal; as well as a processor connected to the load cell of the first reservoir level sensor for processing the first level sensor electrical signal to determine the level of dialysate in the first reservoir, and the processor connected to the load cell of the second reservoir level sensor for processing the second level sensor electrical signal to determine the level of dialysate in the second reservoir.

7. The hemodialysis system of claim 6, wherein the processor disables the hemodialysis system if the first reservoir level sensor or the second reservoir level sensor detects that the level of dialysate in the first reservoir or the second reservoir is below a predetermined threshold.

8. The hemodialysis system of claim 6, wherein the first reservoir and the second reservoir are flexible bags having a volume between 0.5 liters and 5.0 liters, and each of the flexible bags includes a hole for receiving a receiving portion of a horizontal member of a lever arm.

9. The hemodialysis system of claim 6 , further comprising a tilt sensor that measures the tilt of the machine housing to produce a tilt measurement, the tilt sensor being connected to the processor, wherein if the processor detects that the machine housing has tilted beyond a predetermined inclination, the processor disables the hemodialysis system.

10. The hemodialysis system of claim 6 , further comprising a tilt sensor that measures the tilt of the machine housing to produce a tilt measurement, the tilt sensor being connected to the processor, wherein the processor combines the tilt measurements to determine the levels of dialysate in the first and second reservoirs.

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