Patent Application
20240115782
The present invention relates to an artificial kidney system for use in providing dialysis. More particularly, the present invention is directed to a hemodialysis system directed to a hemodialysis system.
Applicant hereby incorporates herein by reference any and all patents and published patent applications cited or referred to in this application.
Hemodialysis is a medical procedure that is used to achieve the 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 result in renal failure.
During hemodialysis, the patient's blood is removed by an arterial line, treated by a dialysis machine, and returned to the body by a venous line. The dialysis machine includes a dialyzer containing a large number of hollow fibers forming a semipermeable membrane through which the blood is transported. In addition, the dialysis machine utilizes a dialysate liquid, containing the proper amounts of electrolytes and other essential constituents (such as glucose), that is also pumped through the dialyzer.
Typically, dialysate is prepared by mixing water with appropriate proportions of an acid concentrate and a bicarbonate concentrate. Preferably, the acid and the bicarbonate concentrate are separated until the final mixing right before use in the dialyzer as the calcium and magnesium in the acid concentrate will precipitate out when in contact with the high bicarbonate level in the bicarbonate concentrate. The dialysate may also include appropriate levels of sodium, potassium, chloride, and glucose.
The dialysis process across the membrane is achieved by a combination of diffusion and convection. The diffusion entails the migration of molecules by random motion from regions of high concentration to regions of low concentration. Meanwhile, convection entails the movement of solute typically in response to a difference in hydrostatic pressure. The fibers forming the semipermeable membrane separate the blood plasma from the dialysate and provide a large surface area for diffusion to take place which allows waste, including urea, potassium and phosphate, to permeate into the dialysate while preventing the transfer of larger molecules such as blood cells, polypeptides, and certain proteins into the dialysate.
Typically, the dialysate flows in the opposite direction to blood flow in the extracorporeal circuit. The countercurrent flow maintains the concentration gradient across the semipermeable membrane so as to increase the efficiency of the dialysis. In some instances, hemodialysis may provide for fluid removal, also referred to as ultrafiltration. Ultrafiltration is commonly accomplished by lowering the hydrostatic pressure of the dialysate compartment of a dialyzer, thus allowing water containing dissolved solutes, including electrolytes and other permeable substances, to move across the membrane from the blood plasma to the dialysate. In rarer circumstances, fluid in the dialysate flow path portion of the dialyzer is higher than the blood flow portion, causing fluid to move from the dialysis flow path to the blood flow path. This is commonly referred to as reverse ultrafiltration. Since ultrafiltration and reverse ultrafiltration can increase the risks to a patient, ultrafiltration and reverse ultrafiltration are typically conducted while supervised by highly trained medical personnel.
Unfortunately, hemodialysis suffers from numerous drawbacks. An arteriovenous fistula is the most commonly recognized access point. To create a fistula, a doctor joins an artery and a vein together. Since this process bypasses the patient's capillaries, blood flows rapidly. For each dialysis session, the fistula must be punctured with large needles to deliver blood into, and return blood from, the dialyzer. Typically, this procedure is done three times a week, for 3-4 hours at an out-patient facility. To a lesser extent, patients conduct hemodialysis at home. Home dialysis is typically done for two hours, six days a week. However, home hemodialysis requires more frequent treatment.
Home hemodialysis suffers from still additional disadvantages. Current home dialysis systems are big, complicated, intimidating, and difficult to operate. The equipment requires significant training. Home hemodialysis systems are currently too large to be portable, thereby preventing hemodialysis patients from traveling. Home hemodialysis systems are expensive and require a high initial monetary investment, particularly compared to in-center hemodialysis where patients are not required to pay for the machinery. Present home hemodialysis systems do not adequately provide for the reuse of supplies, making home hemodialysis economically less feasible to medical suppliers. As a result of the above-mentioned disadvantages, very few motivated patients undertake the drudgery of home hemodialysis.
Furthermore, hemodialysis systems utilizing sorbent filters have not been widely accepted. Unfortunately, the sorbent filters are relatively expensive and can be spent quickly due to ion exchange that occurs as excess dialyzed ions—K+, Ca++, Mg++ and phosphate (PO4) are exchanged for benign or less toxic ions like Na+, H+, bicarbonate (HCO3-) and acetate.
Accordingly, there is a significant need for a hemodialysis system that is transportable, lightweight, easy to use, patient-friendly and thus capable of in-clinic or in-home use.
Moreover, it would be desirable to provide a hemodialysis system that possessed no single-point of failure in the pumps, motors, tubes, or electronics which would endanger a patient.
In addition, it would be desirable to provide a hemodialysis system that was capable of being used in a variety of modes, such as with a filter to cleanse dialysate or without a filter.
In addition, it would be desirable to operate the hemodialysis system in a manner that maximized the life of the sorbent filter.
Aspects of the present invention fulfill these needs and provide further related advantages as described in the following summary.
According to a first aspect of the invention, a hemodialysis system is provided including an arterial blood line for connecting to a patient's artery for collecting blood from a patient, a venous blood line for connecting to a patient's vein for returning blood to a patient, a reusable dialysis machine and a disposable dialyzer.
The arterial blood line and venous blood line may be typical constructions known to those skilled in the art. For example, the arterial blood line may be traditional flexible hollow tubing connected to a needle for collecting blood from a patient's artery. Similarly, the venous blood line may be a traditional flexible tube and needle for returning blood to a patient's vein. Various constructions and surgical procedures may be employed to gain access to a patient's blood including an intravenous catheter, an arteriovenous fistula, or a synthetic graft.
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 passageways, for transporting fluids. The conduits may be constructed in any manner as can be determined by those skilled in the art, such as including flexible medical tubing or non-flexible hollow metal or plastic housings. The blood flow path transports blood in a closed loop system by connecting to the arterial blood line and venous blood line for transporting blood from a patient to the dialyzer and back to the patient. Meanwhile, the dialysate flow path transports dialysate in a closed loop system from a supply of dialysate to the dialyzer and back to the dialysate supply. Both the blood flow path and the dialysate flow path pass through the dialyzer, but the flow paths are separated by the dialyzer's semipermeable membrane.
Preferably, the hemodialysis system contains a reservoir for storing a dialysate solution. The reservoir connects to the hemodialysis system's dialysate flow path to form a closed loop system for transporting dialysate from the reservoir to the hemodialysis system's dialyzer and back to the reservoir. Alternatively, the hemodialysis system possesses two (or more) dialysate reservoirs which can be alternatively placed within the dialysate flow path. When one reservoir possesses contaminated dialysate, dialysis treatment can continue using the other reservoir while the reservoir with contaminated dialysate is emptied and refilled. The reservoirs may be of any size as required by clinicians to perform an appropriate hemodialysis treatment. However, it is preferred that the two reservoirs be the same size and sufficiently small so as to enable the dialysis machine to be easily portable. Acceptable reservoirs are 0.5 liters to 6.0 liters in size. Where the hemodialysis system includes only one reservoir, an acceptable reservoir has a volume of 12.0 liters.
The hemodialysis system preferably possesses one or more heaters thermally coupled to the reservoirs for heating dialysate stored within the reservoir. In addition, the hemodialysis system includes temperature sensors for measuring the temperature of the dialysate within the reservoirs. The hemodialysis system preferably possesses a fluid level sensor for detecting the level of fluid in the reservoir. The fluid level sensor may be any type of sensor for determining the amount of fluid within the reservoir. Acceptable level sensors include magnetic or mechanical float type sensors, conductive sensors, ultrasonic sensors, optical interfaces, and weight measuring sensors such as a scale or load cell for measuring the weight of the dialysate in the reservoir.
Preferably, the dialysis includes three primary pumps. The first and second “dialysate” pumps are connected to the dialysate flow path for pumping dialysate through the dialysate flow path from a reservoir to the dialyzer and back to the reservoir. Preferably, a first pump is positioned in the dialysate flow path “upflow”, (meaning prior in the flow path) from the dialyzer while the second pumps is positioned in dialysate flow path “downflow” (meaning subsequent in the flow path) from the dialyzer. Meanwhile, the hemodialysis system's third primary pump is connected to the blood flow path. This “blood” pump pumps blood from a patient through the arterial blood line, through the dialyzer, and through the venous blood line for return to a patient. It is preferred that the third pump be positioned in the blood flow path, upflow from the dialyzer.
The hemodialysis system may also contain one or more sorbent filters for removing toxins which have permeated from the blood plasma through the semipermeable membrane into the dialysate. Filter materials for use within the filter are 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. Pat. No. 8,647,506 and U.S. Patent Publication No. 2014/0001112.
In a first embodiment, the sorbent filter is connected to the dialysate flow path downflow from the dialyzer so as to remove toxins in the dialysate prior to the dialysate being transported back to a reservoir. In a second embodiment, the filter is outside of the closed loop dialysate flow path, but instead is positioned within a separate closed loop “filter” flow path that selectively connects to either one of the two dialysate reservoirs. For this embodiment, preferably the hemodialysis system includes an additional fluid pump for pumping contaminated dialysate through the filter flow path and its filter.
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 the reservoirs of contaminated dialysate, and the fresh dialysate flow path includes one or more fluid fill lines for transporting fresh dialysate from a supply of fresh dialysate to the reservoirs. One or more fluid pumps may be connected to the drain flow path and/or a fresh dialysate flow path to transport the fluids to their intended destination.
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 assemblies may be of any type of electro-mechanical fluid valve construction as can be determined by one skilled in the art including, but not limited to, traditional electro-mechanical 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 permits or obstructs the flow of fluid through a fluid pathway. Conversely, a three-way valve possesses three ports and functions to shut off fluid flow in one fluid pathway while opening fluid flow in another pathway. In addition, the dialysis machine's valve assemblies may include safety pinch valves, such as a pinch valve connected to the venous blood line for selectively permitting or obstructing the flow of blood through the venous blood line. The pinch valve is provided so as to pinch the venous blood line and thereby prevent the flow of blood back to the patient in the event that an unsafe condition has been detected.
Preferably, the hemodialysis system contains 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 fluid flow (volumetric and/or velocity) within the dialysate flow path. In addition, it is preferred that the dialysis machine contain one or more pressure sensors for detecting the pressure within the dialysate flow path, or at least an occlusion sensor for detecting whether the dialysate flow path is blocked. Preferably, the dialysis machine also possesses one or more sensors for measuring the pressure and/or fluid flow within the blood flow path. The pressure and flow rate sensors may be separate components, or pressure and flow rate measurements may be made by a single sensor.
Furthermore, it is preferred that the hemodialysis system include a blood leak detector (“BLD”) which monitors the flow of dialysate through the dialysate flow path and detects whether blood has inappropriately 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 incorporating a light source which emits light through the dialysate flow path and a light sensor which receives the light that has been emitted through the dialysate flow path. After passing through the dialysate flow path, the received light is then analyzed to determine if the light has been altered to reflect possible blood in the dialysate.
The dialysis machine preferably includes additional sensors including an ammonia sensor and a pH sensor for detecting the level of ammonia and pH within the dialysate. Preferably, the ammonia sensor and pH sensor are in the dialysate flow path immediately downstream of the filter. In addition, the dialysis machine possesses a bubble sensor connected to the arterial blood line and a bubble sensor connected to the venous blood line for detecting whether gaseous bubbles have formed in the blood flow path.
The hemodialysis system possesses a processor containing the dedicated electronics for controlling the hemodialysis system. The processor contains power management and control electrical circuitry connected to the pump motors, valves, and dialysis machine sensors for controlling proper operation of the hemodialysis system. To this end, the hemodialysis system's processor includes memory which is pre-programmed to store one or more patient treatment plans by which a patient is treated. In accordance with the one or more patient treatment plans, the processor controls the dialysate pumps throughout the patient's hemodialysis treatment to have a dialysate flow rate through the dialysate flow path which is not static throughout treatment. The reason to do this would be to maximize solute removal while minimizing dialysate consumption. Because there are many different types of uremic toxins, with vastly different molecular weights, the optimal kinetics for removing each of those different toxins varies. For example, urea is typically removed quickly during a hemodialysis treatment. Conversely, beta2microglobulin is typically removed slowly during a treatment. Accordingly, the hemodialysis system's control processor preferably includes a plurality of different patient treatment plans wherein the dialysate flow rate either decreases and/or increases over periods of time so as maximize different solute removal. For example, the control processor preferably stores and operates patient treatment plans which include changing dialysate flowrates to maximize the removal rates of solutes from a limited supply of dialysate. Furthermore, the hemodialysis system's control processor preferably stores and operates a plurality of different patient treatment plans which change the dialysate flow rate to increase the solute removal provided by a sorbent filter.
For example, it has been found that decreasing the flow rate of the dialysate through the dialysate flow path increases the capacity of the sorbent filter's zirconium phosphate to capture ammonium from urea. Because urea is high at the beginning of a patient's treatment and then decreases as it is removed during treatment, a constant urea concentration requires starting at a high flowrate and reducing it over the course of the treatment. Advantageously any losses of urea clearance from decreasing the dialysate flow rate can be compensated for by extending the duration of the dialysis treatment. Instead, in some embodiments particularly applicable when the hemodialysis machine is utilizing a sorbent filter, the hemodialysis machine includes a control processor which stores and initiates a preprogrammed patient treatment plan wherein the dialysate flow rate decreases throughout the patient's treatment. The decrease in dialysate flow rate may be incremental in a stepped manner. Alternatively, the dialysate flow rate may be decrease in any manner such as linear, exponential, inverse, polynomial, or other relationship which provides for decreasing the dialysate flow rate over time.
Specifically, each patient treatment plan includes a total time period “T(total)” for treating a patient which in turn comprises a plurality of time segments including time segment T1, time segment T2, time segment T3, etc. The patient treatment plan further including a plurality of flow rates including at least a high flow rate which operates for time segment T1, time segment T2, time segment T3, etc. As would be understood by those skilled in the art, where the decrease in dialysate flow rate is changed slowly, such as in a linear or polynomial manner, the time period for each time segment may be extremely small.
For these preferred embodiments, the dialysate treatment starts at a higher dialysate flow rate between 400 to 800 ml/min and the ends at a lower flow rate between 100 to 500 ml/min. More preferably, the dialysis treatment starts at a higher dialysate flow rate between 450 to 800 ml/min and the ends at a lower flow rate between 100 to 450 ml/min. In a preferred embodiment, the patient treatment plan lasts two-six hours and begins treatment with a dialysate flow rate of approximately 400 to 600 ml/min and decreases linearly until ending at a flow rate between 200 to 300 ml/min. In still a more preferred embodiment, the patient treatment plan begins treatment with a dialysate flow rate of approximately 500 ml/min and decreases linearly for approximately four hours until ending at a flow rate of 250 ml/min.
In alternative embodiments where sorbent filter's capture capacity is not of primary concern, the treatment plans stored within the control processor may increase the dialysate flow rate over time. Like the treatment plans wherein the flow rate decreases, for these treatment plans, the dialysate flow rate may increase in an incremental stepped manner, linearly, exponentially, inversely, polynomially, or other relationship which provides for increasing the dialysate flow rate over time. For example, where removing uremic toxins is more important than sorbent capture capacity, then a treatment plan with an increasing dialysate flow rate may be preferred.
Specifically, modelling data for urea spKt/V shows gains of urea clearance from progressively increasing the dialysate flow rates over the course of a treatment. By increasing the dialysate flow rate, the concentration gradient of urea between the dialysate and blood is maximized by speeding up dialysate flow. Furthermore, maximizing this gradient allows for either a reduced need for dialysate volume, or decreased time, to achieve the same amount of urea removal as compared to a treatment with a constant flowrate.
Again, each patient treatment plan wherein the dialysate flow rate is increased includes a total time period “T(total)” for treating a patient which in turn comprises a plurality of time segments including time segment T1, time segment T2, time segment T3, etc. The patient treatment plan further including a plurality of flow rates including at least a low flow rate which operates for predetermined time segment and a high flow rate which operates for a predetermined time segment. As with treatment plans where the dialysate flow rate is decreased over time, the treatment plans having an increasing flow rate which increase in a linear or polynomial manner, the time period for each time segment may be extremely small.
For the increasing dialysate flow rate treatment plans, preferably the dialysate treatment is preprogrammed to start at a lower dialysate flow rate between 50 to 500 ml/min and the ends at a lower flow rate between 100 to 800 ml/min. More preferably, the dialysis treatment starts at a lower dialysate flow rate between 50 to 400 ml/min and the ends at a higher flow rate between 400 to 800 ml/min. In a preferred embodiment, the patient treatment plan lasts one-four hours and begins treatment with a dialysate flow rate of approximately 200 to 300 ml/min and increases linearly until ending at a flow rate between 400 to 600 ml/min. In still a more preferred embodiment, the increasing dialysate flow rate treatment plan begins treatment with a dialysate flow rate of approximately 250 ml/min and decreases linearly for about three hours until ending at a flow rate of 500 ml/min.
In still alternative embodiments, the dialysate treatment plans may include pre-programmed time periods wherein the dialysate flow rate increases for one or more periods of time and dialysate treatment plans includes preprogrammed time periods wherein the dialysate flow rate decreases for one or more periods of time. For these embodiments, the final dialysate flow rate when treatment ends may be higher, lower, or the same as the dialysate flow rate when treatment began.
Advantageously, the dialysis machine provides a hemodialysis system that is transportable, lightweight, easy to use, patient-friendly and capable of in-home use.
In addition, the hemodialysis system provides an extraordinary amount of control and monitoring not previously provided by hemodialysis systems so as to provide enhanced patient safety.
Moreover, the hemodialysis system maximizes the amount of urea that can be removed by the sorbent filter.
Other features and advantages of the present invention will be appreciated by those skilled in the art upon reading the detailed description, which follows with reference to the drawings.
While the present invention is capable of embodiment in various forms, as shown in the drawings, hereinafter will be described the presently preferred embodiments of the invention with the understanding that the present disclosure is to be considered as an exemplification of the invention, and it is not intended to limit the invention to the specific embodiments illustrated.
As best illustrated in
The blood flow path 53 transports blood in a closed loop system by connecting to the arterial blood line 1 and venous blood line 14 to a patient for transporting blood from a patient through the dialyzer 8 and back to the patient. Preferably, the hemodialysis system includes a supply of heparin 6 and a heparin pump connected to the blood flow path 1. The heparin pump delivers small volumes of heparin anticoagulant into the blood flow to reduce the risk of blood clotting in the machine. The heparin pump can take the form of a linearly actuated syringe pump, or the heparin pump may be a bag connected with a small peristaltic or infusion pump.
The hemodialysis system includes a dialyzer 8 in the dialysate flow path 54 which is of a construction and design known to those skilled in the art. Preferably, the dialyzer 8 includes a large number of hollow fibers which form a semipermeable membrane. Suitable dialyzers can be obtained from Fresenius Medical Care, Baxter International, Inc., Nipro Medical Corporation, and other manufacturers of hollow fiber dialyzers. Both the blood flow path and dialysate flow path travel through the dialyzer 8 which possesses an inlet for receiving dialysate, an outlet for expelling dialysate, an inlet for receiving blood from a patient, and an outlet for returning blood to a patient. Preferably, the dialysate flows in the opposite direction to the blood flowing through the dialyzer with the dialysate flow path isolated from the blood flow path by a semipermeable membrane (not shown). As illustrated in
Preferably, the hemodialysis system includes three primary pumps (5, 26 and 33) for pumping blood and dialysate. For purposes herein, the term “pump” is meant to refer to both the pump actuator which uses suction or pressure to move a fluid, and the pump motor for mechanically moving the actuator. Suitable pump actuators may include an impeller, piston, diaphragm, the lobes of a lobe pump, screws of a screw pump, rollers or linear moving fingers of a peristaltic pump, or any other mechanical construction for moving fluid as can be determined by those skilled in the art. Meanwhile, the pump's motor is the electromechanical apparatus for moving the actuator. The motor may be connected to the pump actuator by shafts or the like. In a preferred embodiment, the dialysate and/or blood flow through traditional flexible tubing and each of the pump actuators consist of a peristaltic pump mechanism wherein each pump actuator includes a rotor with a number of cams attached to the external circumference of the rotor in the form of “rollers”, “shoes”, “wipers”, or “lobes” which compress the flexible tube. As the rotor turns, the part of the tube under compression is pinched closed (or “occludes”) forcing the fluid to be pumped through the tube. Additionally, as the tube opens to its natural state after the passing of the cam fluid flow is induced through the tube.
The first and second primary pumps (26 and 33) are connected to the dialysate flow path for pumping dialysate through the dialysate flow path from a reservoir (17 or 20) to the dialyzer 8 and back to the reservoir (17 or 20). A first pump 26 is connected to the dialysate flow path “upstream”, (meaning prior in the flow path) from the dialyzer 8 while the second pump 33 is connected to the dialysate flow path “downstream” (meaning subsequent in the flow path) from the dialyzer 8. Meanwhile, the hemodialysis system's third primary pump 6 is connected to the blood flow path. The third pump 6, also referred to as the blood pump, pumps blood from a patient through the arterial blood line, through the dialyzer 8, and through the venous blood line for return to a patient. It is preferred that the third pump 6 be connected to the blood flow path upstream from the dialyzer. The hemodialysis system may contain more or less than three primary pumps. For example, the dialysate may be pumped through the dialyzer 8 utilizing only a single pump. However, it is preferred that the hemodialysis system contain two pumps including a first pump 26 upstream from the dialyzer 8 and a second pump 33 downflow from the dialyzer 8.
Preferably, the hemodialysis system contains one or more reservoirs (17 and 20) for storing dialysate solution. Where the system includes two reservoirs, both of the reservoirs (17 and 20) may be connected simultaneously to the dialysate flow path 54 to form one large source of dialysate. Alternatively, 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 a dialysate from one of the two reservoirs to the dialyzer and back to that reservoir. After the dialysate in a first reservoir 17 has been used, is no longer sufficiently clean, or does not possess appropriate chemical properties, the hemodialysis system's valve 21 is controlled to remove the first reservoir 17 from the dialysate flow path and substitute the second reservoir 20, which has fresh dialysate 75, into the dialysate flow path. Thus, when one reservoir possesses contaminated dialysate 76, and the reservoir needs to be emptied and refilled with freshly generated dialysis fluid 75, dialysis treatment can continue using the other reservoir.
In this manner, the hemodialysis system may switch between each reservoir 17 and 20 times over the course of the treatment. Furthermore, the presence of two reservoirs as opposed to one reservoir allows for the measurement of the flow rate for pump calibration or ultrafiltration measurement, while isolating the other reservoir while it is being drained or filled. Though the reservoirs may be of any size as required by clinicians to perform an appropriate hemodialysis treatment, preferred reservoirs have a volume between 0.5 liters and 5.0 liters.
The hemodialysis system also contains a sorbent filter (also referred to herein as a “filter”) connected to the dialysate flow path 54 for removing toxins which have permeated from the blood plasma through the semipermeable membrane into the dialysate. In a first embodiment, the filter 36 is connected to the dialysate flow path 54 downstream from the dialyzer so as to remove toxins transferred by the dialyzer into the dialysate prior to the dialysate being transported to the reservoir. Filter materials for use with the dialysis machine 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 containing layers of zirconium oxide, zirconium phosphate and carbon. Acceptable materials are described in U.S. Pat. No. 8,647,506 and U.S. Patent Application Publication No. 2014/0001112. Other acceptable filter materials can be developed and utilized by those skilled in the art without undue experimentation. The filter housing may or may not include a vapor membrane capable of releasing gases, but not liquids, and particularly not the dialysate liquid flowing through the filter.
In the event that the hemodialysis system possesses a sorbent filter, preferably the dialysis flow path 54 incorporates safety features in the form of an ammonium sensor 37 and a pH sensor 38. These sensors may be located immediately downstream of the sorbent cartridge 36, or immediately downstream of the one or more reservoirs. For example, as illustrated in
It is also preferred that the hemodialysis system possesses a reagent bag 39 and pump 40 for introducing reagents into the dialysate flow path 54 immediately after the sorbent filter 36. The reagent bag 39 holds a concentrated solution of salts and ions to reinfuse the filter dialysis fluid. Through the action of filtering waste, the sorbent filter 36 also removes beneficial ions from the dialysis fluid, such as calcium and salt. Before the filtered dialysis fluid can be recirculated, it must be reinfused with calcium and salts so that the dialysis fluid does not draw these beneficial ions from the patient's blood. Preferably, the reagent bag 39 will hold between 1 and 3 liters of concentrated reagent. The reagent pump 40 can be any type of pump such as a peristaltic pump or diaphragm pump. To ensure that the hemodialysis system is introducing the proper amount of salts and ions into the dialysate, a conductivity sensor 41 may be positioned within 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 dialysis fluid. In the event that the total dissolved solids are detected to not be within a prescribed range, the operation of the pump 40 can be increased or decreased, or alternatively, treatment can be stopped entirely. For example, if a fault state is detected in the dialysis fluid, then the fluid can be redirected by 3-way valves 29 and 32 through the bypass path 30 so that dialysate does not meet the patient's blood in the dialyzer. More specifically, the 3-way valve 29 directs dialysis fluid to the dialyzer's inlet and the 3-way valve 32 directs dialysate from the dialysate outlet back through the dialysate flow path 54. However, if a fault state is detected in the dialysis fluid, such as the temperature being too low or excessive ammonium ions are detected in the dialysate, then the dialysis fluid is redirected by 3-way valves 29 and 32 to bypass the dialyzer 8, through bypass path 30.
For the embodiment illustrated in
For the embodiment illustrated in
As an alternative to using the sorbent filter 36, the hemodialysis system includes a supplemental “bypass” flow path 35 that selectively transports dialysis around the sorbent filter 36. The bypass flow path includes a 3-way valve 34 upstream of the filter. The 3-way valve 34 is switched to direct the dialysis fluid through sorbent filter 36, or alternatively, the 3-way valve 34 is switched to direct dialysate through the bypass flow path 35 to avoid the sorbent filter 36. For example, if a sorbent filter is not available, or if the sorbent filter has become spent, or if a sorbent filter is not required for a particular patient treatment, then the 3-way valve 34 is switched to direct the dialysis fluid down the bypass flow path 35.
In an alternative embodiment illustrated in
This embodiment of the hemodialysis machine includes a system for introducing reagents into the filter flow path. As illustrated in
In the embodiment illustrated in
In the embodiment illustrated in
With reference still to
In addition, the hemodialysis system possesses various sensors for monitoring hemodialysis, and in particular, the dialysate flow path and blood flow path. To this end, the hemodialysis system preferably has one or more flow sensors 25 connected to the dialysate flow path for detecting fluid flow (volumetric and/or velocity) within the dialysate flow path. In addition, it is preferred that the hemodialysis system contain one or more pressure, or occlusion, sensors (9 and 27) for detecting the pressure within the dialysate flow path. Preferably, the hemodialysis system also possesses one or more sensors for measuring the pressure (4 and 7) and/or fluid flow 11 within the blood flow path.
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 possesses level sensors for detecting the level of fluid in the reservoirs (17 and 20). Preferred level sensors may include either capacitive fluid level sensors (15 and 18) embodiment, the weight, and therefore level of dialysate, of each reservoir 17 and 20 is measured by a level sensor (16 or 19) connected to the processor.
Furthermore, it is preferred that the hemodialysis system includes a blood leak detector 31 which monitors the flow of dialysate through the dialysate flow path and detects whether blood has inappropriately diffused through the dialyzer's semipermeable membrane into the dialysate flow path.
Preferably, the hemodialysis system also contains a first pinch valve 2 connected to the arterial blood line 1 for selectively permitting or obstructing the flow of blood through the arterial blood line, and a second pinch valve 13 connected to the venous blood line 14 for selectively permitting or obstructing the flow of blood through the venous blood line. The pinch valves are provided so as to pinch the arterial blood line 1 and venous blood line 14 to prevent the flow of blood back to the patient in the event that any of the sensors have detected an unsafe condition. Providing still additional safety features, the hemodialysis system includes blood line bubble sensors (3 and 12) to detect if an air bubble travels backwards down the arterial line (blood leak sensor 3) or venous line (blood leak sensor 12). Further, the blood flow path 53 may include a bubble trap 10 which has a pocket of pressurized air inside a plastic housing. Bubbles rise to the top of the bubble trap, while blood continues to flow to the lower outlet of the trap.
This component reduces the risk of bubbles traveling into the patient's blood. To control the flow and direction of blood and dialysate through the hemodialysis system, the hemodialysis system includes a variety of fluid valves for controlling the flow of fluid through the various flow paths of the hemodialysis system. The various valves include pinch valves and 2-way valves which must be opened or closed, and 3-way valves which divert dialysate through a desired flow pathway as intended. In addition to the valves identified above, the hemodialysis system includes a 3-way valve 21 located at the reservoirs' outlets which determines from which reservoir (17 or 20) dialysate passes through the dialyzer 8. An additional 3-way valve 42 determines to which reservoir the used dialysate is sent to. Finally, 2-way valves 51 and 52 (which may be pinch valves) are located at the reservoirs' inlets to permit or obstruct the supply of fresh dialysate to the reservoirs 17 and 20). Of course, alternative valves may be employed as can be determined by those skilled in the art, and the present invention is not intended to be limited the specific 2-way valve or 3-way valve that has been identified.
In addition, the hemodialysis system includes a processor 77 and a user interface (not shown). The processors contain the dedicated electronics for controlling the hemodialysis system including the hardware and software, and power management circuitry connected to the pump motors, sensors, valves and heater for controlling proper operation of the hemodialysis system. The processor monitors each of the various sensors to ensure that hemodialysis treatment is proceeding in accordance with a preprogrammed procedure input by medical personnel into the user interface. The processor may be a general-purpose computer or microprocessor including hardware and software as can be determined by those skilled in the art to monitor the various sensors and provide automated or directed control of the heater, pumps, and pinch valve. The processor may be located within the electronics of a circuit board or within the aggregate processing of multiple circuit boards and memory cards.
Also not shown, the hemodialysis system includes a power supply for providing power to the processor, user interface, pump motors, valves, and sensors. The processor is connected to the dialysis machine sensors (including reservoir level sensors (15, 16, 18 and 19), blood leak sensor 31, ammonia sensor 37, pressure and flow rate 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 & 49), and pinch valves (2 and 13) by traditional electrical circuitry.
In operation, the processor is electrically connected to the first, second and third primary pumps (5, 26, and 33) for controlling the activation and rotational velocity of the pump motors, which in turn controls the pump actuators, which in turn controls the pressure and fluid velocity of blood through the blood flow path and the pressure and fluid velocity of dialysate through the dialysate flow path. By independently controlling operation of the dialysate pumps 26 and 33, the processor can maintain, increase, or decrease the pressure and/or fluid flow within the dialysate flow path within the dialyzer. Moreover, by controlling all three pumps independently, the processor can control the pressure differential across the dialyzer's semipermeable membrane to maintain a predetermined pressure differential (zero, positive or negative), or maintain a predetermined pressure range. For example, most hemodialysis is performed with a zero or near zero pressure differential across the semipermeable membrane, and to this end, the processor can monitor and control the pumps to maintain this desired zero or near zero pressure differential. Alternatively, the processor may monitor the pressure sensors and control the pump motors, and in turn pump actuators, to increase and maintain positive pressure in the blood flow path within the dialyzer relative to the pressure of the dialysate flow path within the dialyzer. Advantageously, this pressure differential can be affected by the processor to provide ultrafiltration and the transfer of free water and dissolved solutes from the blood to the dialysate.
In the preferred embodiment, the processor monitors the blood flow sensor 11 to control the blood pump flowrate. It uses the dialysate flow sensor 25 to control the dialysate flow rate from the upstream dialysate pump. The processor then uses the reservoir level sensors (15, 16, 18 and 19) to control the flowrate from the downstream dialysate pump 33. The change in fluid level (or volume) in the dialysate reservoir is identical to the change in volume of the patient. By monitoring and controlling the level in the reservoir, forward, reverse, or zero ultrafiltration can be accomplished.
With reference to
In addition, the following table shows linear reductions in dialysate flow rate wherein the % change in spKt/V is from a baseline of 600 ml/min for a period of 240 minutes. As reflected in the table, for a dialysate flow rate of 500-300 ml/min in a 35 L distributed urea volume patient, the spKt/V is 1.54. This is similar to the 1.57 spKt/V for a constant flow rate of 400 ml/min. Similarly, for a dialysate flow rate of 550-250 ml/min in a 35 L distributed urea volume patient, the spKt/V is 1.52, which is still similar to the 1.57 spKt/V for a constant flow rate of 400 ml/min. This tells us that the average of the dialysate flow rate matters more than ramping the flow rate for affecting urea removal.
But again, the sorbent cartridge 36 is capable of absorbing more urea during treatment operated at the decreasing dialysate flow rate. Also of importance, urea is typically released into the dialysate at greater levels at the beginning of a hemodialysis treatment compared to the end of treatment. Thus, a higher dialysate flow rate at the beginning of treatment is preferred. To balance these counteracting influences, it is preferred that a patient's treatment commence with the dialysate flowing at a high flow rate at the beginning of treatment, but that dialysate flow rate decrease through a patient's treatment.
There are other reasons to change the dialysate flowrates over the course of a treatment besides optimizing urea removal in a sorbent filter. Balancing the volume of dialysate needed for a treatment with the length of a treatment can be accomplished by varying the dialysate flowrate over the course of the treatment. When the urea concentration is high at the beginning of treatment, a high dialysate flowrate is helpful in quickly removing urea from the blood. As the urea concentration decreases, decreasing the flowrate does not overly change the urea that can be removed from the blood, but the amount of dialysate consumed can be decreased.
To implement a preprogrammed patient treatment plan with decreasing dialysate flow rate, the processor 77 is connected to the dialysate flow sensor 25 to monitor the flow of dialysate, and the processor 77 is connected to the dialysate pumps 26 and 33 to control the rate that dialysate flows through the dialysate flow path. In addition, the processor 77 includes memory 78 which stores one or more patient treatment plans by which a patient is treated. The patient treatment plan includes the desired flow rates that dialysate is intended to flow at different time segments throughout the patient's treatment. As illustrated in
Specifically, each patient treatment plan includes a total time period “T(total)” for treating a patient which in turn comprises a plurality of time segments including time segment T1, time segment T2, time segment T3, etc. The patient treatment plan further includes a plurality of flow rates including at least a high flow rate which operates for time segment T1. The treatment plan further includes time segment T2, time segment T3, etc. As would be understood by those skilled in the art, where the decrease in dialysate flow rate is changed substantially continuously, such as in a linear or polynomial manner, the time period for each time segment is considered to be extremely small.
Preferably, the dialysis treatment starts at a higher dialysate flow rate, such as between 400 to 800 ml/min, and the ends at a lower flow rate between 100 to 500 ml/min. However, a dialysis treatment may start even above 800 ml/min and end at a lower flow rate than 100 ml/min. More preferably, the dialysis treatment starts at a higher dialysate flow rate between 450 to 800 ml/min and the ends at a lower flow rate between 100 to 450 ml/min. However, another patient may require a different treatment protocol. For example, in another preferred embodiment, the patient treatment plan lasts four hours and begins treatment with a dialysate flow rate of approximately 400 to 600 ml/min and decreases linearly until ending at a flow rate between 200 to 300 ml/min.
In the preferred embodiment illustrated in
Decreasing the dialysate flow rate throughout the patient's treatment is believed ideal where a sorbent cartridge is employed to maximize the capture of uremic toxins However, where a sorbent cartridge is not employed, in alternative embodiments illustrated in
With reference also to
For the increasing dialysate flow rate treatment plans, preferably the dialysate treatment starts at a lower dialysate flow rate between 50 to 500 ml/min and then ends at a higher flow rate between 100 to 800 ml/min. More preferably, the dialysis treatment starts at a lower dialysate flow rate between 50 to 400 ml/min and the ends at a higher flow rate between 400 to 800 ml/min. In a preferred embodiment, the patient treatment plan lasts one-four hours and begins treatment with a dialysate flow rate of approximately 200 to 300 ml/min and increases linearly until ending at a flow rate between 400 to 600 ml/min. In still a more preferred embodiment, the increasing dialysate flow rate treatment plan begins treatment with a dialysate flow rate of approximately 250 ml/min and increases linearly for about three hours until ending at a flow rate of 500 ml/min.
As illustrated in
These increasing dialysate flow rate treatment plans may be modified in accordance with a patient's needs. For example, an acceptable modified plan may include starting and maintaining treatment at a low flow rate of 250 ml/min for a predetermined time period, such as thirty (30) minutes, to monitor the patient's condition. Thereafter, if the patient's condition seems acceptable, the dialysate flow rate may be increased in a linear, stepped, logarithmic, exponential, or other manner to maximize uremic toxin removal.
With reference to
For these embodiments wherein the patient treatment plan includes both pre-programmed time periods wherein the dialysate flow rate increases and preprogrammed time periods wherein the dialysate flow rate decreases, the final dialysate flow rate may be higher, lower, or the same as the final dialysate flow rate. Again, the increases and decreases in dialysate flow rate may be linear, stepped, logarithmic, exponential, or other manner to provide benefits including, but not limited to maximizing uremic toxin removal by a sorbent cartridge, maximizing solute removal by a limited quantity of dialysate, facilitating patient monitoring, and/or for other reasons as can be determined by those skilled in the art.
To maintain proper treatment of a patient, the processor monitors all of the various sensors to ensure that the hemodialysis machine is operating efficiently and safely, and in the event that an unsafe or non-specified condition is detected, the processor corrects the deficiency or ceases further hemodialysis treatment. For example, if the venous blood line pressure sensor 9 indicates an unsafe pressure or the bubble sensor 12 detects a gaseous bubble in the venous blood line, the processor signals an alarm, the pumps are deactivated, and the pinch valves are closed to prevent further blood flow back to the patient. Similarly, if the blood leak sensor 31 detects that blood has permeated the dialyzer's semipermeable membrane, the processor signals an alarm and ceases further hemodialysis treatment.
The dialysis machine's user interface may include a keyboard or touch screen (not shown) for enabling a patient or medical personnel to input commands concerning treatment or enable a patient or medical personnel to monitor performance of the hemodialysis system. Moreover, the processor may include Wi-Fi or Bluetooth connectivity for the transfer of information or control to a remote location.
Hereinafter will be identified the various components of the preferred hemodialysis system with the numbers corresponding to the components illustrated in the Figures.
The hemodialysis system provides increased flexibility of treatment options based on the required frequency of dialysis, the characteristics of the patient, the availability of dialysate or water and the desired portability of the dialysis machine. For all treatments, the blood flow path 53 transports blood in a closed loop system by connecting to the arterial blood line 1 and venous blood line 14 to a patient for transporting blood from a patient to the dialyzer and back to the patient.
With reference to
Meanwhile, while the first reservoir is being emptied and refilled, hemodialysis treatment continues using the second reservoir (17 or 20). As illustrated in
In a second embodiment illustrated in
As illustrated in
In still an additional embodiment illustrated in
Like the prior embodiments, dialysis treatment is implemented while switching back and forth between reservoirs 17 and 20. With reference to
With reference to
Like embodiments illustrated in
Conversely, the embodiment of the hemodialysis system illustrated in
In closing, regarding the exemplary embodiments of the present invention as shown and described herein, it will be appreciated that a hemodialysis system is disclosed. The principles of the invention may be practiced in a number of configurations beyond those shown and described, so it is to be understood that the invention is not in any way limited by the exemplary embodiments, but is generally directed to a hemodialysis system and is able to take numerous forms to do so without departing from the spirit and scope of the invention. It will also be appreciated by those skilled in the art that the present invention is not limited to the particular geometries and materials of construction disclosed, but may instead entail other functionally comparable structures or materials, now known or later developed, without departing from the spirit and scope of the invention. Furthermore, the various features of each of the above-described embodiments may be combined in any logical manner and are intended to be included within the scope of the present invention.
Groupings of alternative embodiments, elements, or steps of the present invention are not to be construed as limitations. Each group member may be referred to and claimed individually or in any combination with other group members disclosed herein. It is anticipated that one or more members of a group may be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is deemed to contain the group as modified.
Unless otherwise indicated, all numbers expressing a characteristic, item, quantity, parameter, property, term, and so forth used in the present specification and claims are to be understood as being modified in all instances by the term “about.” As used herein, the term “about” means that the characteristic, item, quantity, parameter, property, or term so qualified encompasses a range of plus or minus ten percent above and below the value of the stated characteristic, item, quantity, parameter, property, or term. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the Specification and attached claims are approximations that may vary. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical indication should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and values setting forth the broad scope of the invention are approximations, the numerical ranges and values set forth in the specific examples are reported as precisely as possible. Any numerical range or value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Recitation of numerical ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate numerical value falling within the range. Unless otherwise indicated herein, each individual value of a numerical range is incorporated into the present Specification as if it were individually recited herein.
The terms “a,” “an,” “the” and similar referents used in the context of describing the present invention (especially in the context of the following claims) are to 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 otherwise 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 present invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the present specification should be construed as indicating any non-claimed element essential to the practice of the invention.
Specific embodiments disclosed herein may be further limited in the claims using consisting of or consisting essentially of language. When used in the claims, whether as filed or added per amendment, the transition term “consisting of” excludes any element, step, or ingredient not specified in the claims. The transition term “consisting essentially of” limits the scope of a claim to the specified materials or steps and those that do not materially affect the basic and novel characteristic(s). Embodiments of the present invention so claimed are inherently or expressly described and enabled herein.
It should be understood that the logic code, programs, modules, processes, methods, and the order in which the respective elements of each method are performed are purely exemplary. Depending on the implementation, they may be performed in any order or in parallel, unless indicated otherwise in the present disclosure. Further, the logic code is not related, or limited to any particular programming language, and may comprise one or more modules that execute on one or more processors in a distributed, non-distributed, or multiprocessing environment.
While several particular forms of the invention have been illustrated and described, it will be apparent that various modifications can be made without departing from the spirit and scope of the invention. Therefore, it is not intended that the invention be limited except by the following claims. We claim:
The present application is a continuation-in-part of U.S. patent Ser. No. 17/334,393 filed on May 28, 2021, which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 17334393 | May 2021 | US |
| Child | 18228491 | US |
