US20130264250A1 - Batch filtration system for preparation of sterile fluid for renal replacement therapy - Google Patents

Abstract

A first connector of a connector assembly of a sterile batch container can be unsealed. The connector assembly can be attached to a filling port of the sterile batch container and can have a sterile filter arranged between the filling port and the first connector. The first connector can be coupled so as to receive produced purified water. A transmembrane pressure can be monitored across the sterile filter while flowing the purified water through the connector assembly into the sterile batch container so as to provide a sterile fluid stored therein. The connector assembly can be detached from the filling port of the sterile batch container. After the detaching, the sterile batch container can be coupled to the blood treatment system. In response to a change in the transmembrane pressure exceeding a predefined level, an alarm signal can be generated.

Description

BACKGROUND OF THE INVENTION
• During hemofiltration, hemodialysis, hemodiafiltration, ultrafiltration, and other forms of renal replacement therapy, blood is drawn from a patient, passed through a filter, and returned to the patient. Depending on the type of treatment, fluids and electrolytes are exchanged in the filter between a dialysate and/or extracted from the blood by filtration. One effect may be a net loss of fluid and electrolytes from the patient and/or exhaustion of dialysate, with a concomitant need for its replenishment, again depending on the type of treatment. To replace fluid lost from the patient and keep the patient from dehydrating, replacement fluid may be injected into the patient at a rate that matches a rate of loss, with an adjustment for a desired net change in the patient's fluid complement. To replace exhausted dialysate, fresh dialysate is continuously circulated through the filter.
• Conventionally, dialysate and/or replacement fluid is supplied from either of two sources: batches of fluid, typically in multiple bags, or a continuous source of water that is sterile-filtered and added to concentrated electrolytes to achieve the required dilution level. Because replacement fluid is injected directly into the patient, replacement fluid must be sterile. When either method is used to generate replacement fluid, there is a risk of contamination of the fluid. Contamination may occur, for example, at the point where bags of fluid are accessed (“spiked”) or at any connection in the fluid circuit linking the source to the patient.
• In many instances, such therapies may require a large quantity of sterile fluid. A typical way to provide the large quantity of replacement fluid is to provide multiple bags of replacement fluid, dialysate, or infusate. The connection of these bags of fluid to an extracorporeal blood circuit, there is a risk of touch- contamination resulting in the introduction of biological contaminants into the fluids. Presently, methods of producing large volumes of dialysate from tap water are known, but each requires complex water purification and standardization equipment, since impurities and cleaning additives such as chlorine vary greatly in tap water from municipality to municipality and within a municipality over time. (See Twardowski U.S. Pat. Nos. 6,146,536 and 6,132,616.) Moreover, dialysate solution, whether prepared online or prepackaged, while of the proper concentration for use as a sterile replacement fluid, never enters the patient's body. Instead, dialysate flows past a semipermeable membrane that permits ions to be exchanged across the membrane until a balance between their concentrations in blood and their concentrations in the dialysis is achieved. This is effective to remove impurities from the blood and to add missing electrolytes to the blood. Because it does not have to be infused, dialysate is less expensive than solutions prepared as replacement fluids, which are injected directly into a patient.
• Attempts to render dialysate sufficiently sterile for use as a replacement fluid in hemofiltration and hemodiafiltration have focused on continuous sterilization processes that require a separate dialysate filtration/purification apparatus that must be periodically purged and verified to provide sufficient constant flow of sterile replacement fluid required for hemofiltration. (See Chavallet U.S. Pat. Nos. 6,039,877 and 5,702,597.) Such devices are necessarily complicated and require separate pumping systems for the sterilization process. In addition, the rate of supply of dialysate for such systems is very high, requiring an expensive filter to be used. The same high-rate problem exists for the generation of replacement fluid for hemofiltration, and therefore also requires an expensive filter.
SUMMARY OF THE INVENTION
• In the present invention, sterile replacement fluid or dialysate may be generated in batch form by sterile-filtering. According to embodiments of inventions disclosed, non-sterile fluid is passed through a filter prior to treatment to prepare a batch of replacement fluid. This process may be permitted to take any length of time because the rate of flow of non-sterile replacement fluid (or components thereof) through the filter is completely independent of the rate of consumption by the renal therapy. Because the filters used for sterile-filtering tend to be expensive, it may be desirable for such a batch process to employ a small filter for such filtration. Such a filter can have a flow capacity that is much lower than that required for real-time filtering of the replacement fluid (or components). In addition to preparation of sterile fluid from non-sterile fluid, embodiments of inventions disclosed may be used to sterilize already-sterile fluid as a precaution against touch contamination.
• Generally replacement fluid is heated before being infused into a patient. This is often accomplished by heating the fluid as it is being infused with a heater with sufficient heating capacity. The capacity of the heater must be matched to the mass flow of the fluid and the temperature rise required. In a batch preparation process, where a batch of fluid is prepared over a substantial period before use, a small heater may heat the replacement fluid over a long period of time. Insulation may be provided to prevent heat loss. An insulating outer container for the sterile replacement fluid may be provided. For example, the container may be an insulated box with room for one or more large disposable sterile bags of the type normally used for infusible fluids.
• The preparation of warm sterile replacement fluid may be automated by a control process that permits a user to set up the fluids and other materials well in advance of a scheduled treatment. The process would ensure that the replacement fluid is sterilized and heated to the proper temperature when the treatment is to begin.
• The automation process may be permit the user to select how far in advance of the treatment the preparation should be performed. This may be useful, for example, where a particular source of replacement fluid has proved to release more than a usual quantity of dissolved gases upon heating. Heating the replacement fluid and permitting it to settle for a time before it is used may allow gases to come out of solution and settle at the top of the batch vessel or vessels. The automation process may be incorporated in the control functions of renal therapy machine.
• The invention or inventions will be described in connection with certain preferred embodiments, with reference to the following illustrative figures so that it may be more fully understood. With reference to the figures, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present invention or inventions only, and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention or inventions. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention or inventions, the description taken with the drawings making apparent to those skilled in the art how the several forms of the invention or inventions may be embodied in practice.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a schematic illustration of a standalone/retrofit apparatus system for batch filtration of a sterile replacement fluid.
• FIG. 2 is a flow chart illustrating an exemplary control procedure applicable to various embodiments of the invention including those ofFIGS. 1 and 3.
• FIG. 3 is a schematic illustration of a blood treatment machine with an attached subsystem for batch preparation of sterile replacement fluid.
• FIGS. 4A and 4B are illustrations of fluid filters that may be use in various embodiments of the invention.
• FIG. 5 illustrates an exemplary blood treatment system with a filter used to sterilize and/or degas replacement fluid during treatment.
• FIGS. 6-8 illustrate a blood treatment machine and cartridge providing various supporting mechanical features for the embodiment ofFIG. 5 and further embodiments, including one in which a quality of replacement fluid is sensed before infusion.
• FIG. 9 illustrates a disposable fluid circuit kit which may support various embodiments of the invention.
• FIG. 10 illustrates a set up for priming a blood treatment process, which components of the invention may be used to support.
• FIG. 11 illustrates a portion of a blood treatment machine that allows a pump used as part of the blood treatment to also be used to control the filtering of fluid to provide a batch of infusible replacement fluid.
• FIG. 12 illustrates replacement fluid container tubing set.
• FIG. 13 illustrates a replacement fluid preparation apparatus.
• FIGS. 14,15, and16 illustrate portions of the replacement fluid preparation apparatus ofFIG. 13.
DETAILED DESCRIPTION
• Referring toFIG. 1, afilter160 filters fluid from a source offluid150 to generate a batch ofsterile replacement fluid130. Thefilter160 may be, and preferably is, a microporous filter that blocks all materials except dissolved electrolytes and water. Thus, the result of the filtration process is to sterilize the raw fluid from the source offluid150. The source offluid150 may be a container of sterile or non-sterile replacement fluid, one or more containers of constituents which, when combined, form a proper replacement fluid. Any of the latter may include a continuous source such as a water tap. One or more conduit elements form aline120 to convey the source fluid150 through thefilter160 and into abatch container147.
• The latter may be any type of sterile, preferably disposable container, for example, a large IV bag. It may also include a number of such containers appropriately interconnected to permit flow into and out of them in the fashion ofcontainer147.
• Included in the conveyance from source fluid150 tosterile replacement fluid130 may be apump190, such as a peristaltic pump. The pressure at an outlet of thefilter160 may be sensed by apressure sensor162 and thepump190 controlled by acontroller170 to insure a predefined transmembrane pressure (TMP) threshold of thefilter160 is not breached. The TMP may be maintained at a maximum safe level to maximize throughput. Note that complexity may be avoided if thesource fluid150 is arranged such as to maintain a desired TMP at thefilter160 without the need of apump190 orpressure sensor162. For example, the source fluid150 may be provided by a batch container elevated at a certain height to provide a desired head. Note that acontrol valve165 or a speed of thepump190 may be used to regulate the flow rate to maintain desired TMP limits.
• A control/shutoff valve180 may provide thecontroller170 the ability to stop the flow of fluid through thefilter160 once a desired volume is reached. Aheater185 may be provided to warm thesterile replacement fluid130 to prepare it for use. Aninsulated container145 may be used to reduce heat loss so thatheater185 can be a relatively low power type. Theheater185 may be controlled by thecontroller170 to ensure thereplacement fluid130 is at a desired temperature when required to be used. Alternatively theheater185 can be controlled by an independent device actuated by, for example, a pressure sensor (not shown) triggered by the flow of fluid into thebatch container147, a timer (not shown) settable to trigger based on a predefined treatment time, or some other means. Preferably, in either case, a temperature regulator (e.g., atemperature sensor183 combined with logic in controller170) regulates power to the heater to ensure a required temperature is maintained and not exceeded. Thetemperature sensor183 may be used to sense the quantity of sterile replacement fluid by the rate of detected temperature increase versus heater output. Thetemperature sensor183,heater185, andsterile replacement fluid130 can be modeled in any desired fashion. For example one may neglect all but the thermal mass of the RF, assume perfect heat transfer (including assuming the RF fluid to be isothermal). Then, the mass would be given by the product of the temperature change, the thermal capacitance of the fluid, and the heat output rate of the heater. More complex theoretical or empirical algorithms would be a simple matter to derive and implement. Once the mass of fluid is calculated to be below a certain level, thecontroller170 may be programmed to respond in accord with the assumption the sterile RF is exhausted. Equivalently, thecontroller170 may simply respond to some predefined rate of temperature rise of thetemperature sensor183.
• When the temperature of thesterile replacement fluid130 is raised, dissolved gas may come out of solution. This may cause bubbles to accumulate inside thereplacement fluid container247, which is undesirable because of the risk of infusing bubbles into the patient's bloodstream. To help ameliorate that problem, a vibrator or ultrasonic transducer may be provided183 to cause bubbles to coalesce and rise to a top of thecontainer147. As a result, bubble-free replacement fluid may be drawn through theoutlet148.
• Aconnector195 may be provided for connecting the source fluid to theline120. The connector may be a luer, spike, threaded adapter, or any other suitable type. Although the various controls indicated above are shown to be controlled anautomatic controller170, each may be controlled also by manual mechanisms.
• TheFIG. 1 embodiment allows replacement fluid to be prepared in batch for later use. Thus, the rate of filtration of replacement fluid need not match the requirements of the treatment process or preparatory steps such as priming. As a result, a low capacity filter may be used for thefilter160. For example, typically only a small quantity of expensive media is required to make a small-capacity filter and as such, the cost of a low capacity filter can be much smaller than a high capacity filter.
• Also, other features found in high capacity filters, such as a large ratio of media surface to volume of the filter module are achievable only by means of folding or forming media into shapes that can be difficult to manufacture, such as tubes. Thus, savings can be achieved in simplification of the configuration of the filter as well. Relatively small filters with simple planar media held in plastic casings are available and suitable for this purpose.
• The configuration ofFIG. 1 may be retrofitted for use with an existing treatment system. For this purpose, theoutlet148 may provide with any required connection adapter. Auser interface175 for entering data into thecontroller170 may be provided as well.
• Referring now toFIG. 2, a control algorithm for controlling theheater185, pump190,valves165/180, etc. begins with the a setting of a time for treatment S10, for example by entering a time into thecontroller170 via a user interface (UI)175. The time can be entered manually or automatically by means of, for example, a data signal from a remote source via a switched or network circuit. The time for treatment may be obtained from a treatment calendar entered into thecontroller170, which also may be obtained from a remote source. In the present simple algorithm, first and second time intervals T1 and T2 are defined representing the interval required for filtration of RF and the interval required for heating of RF, respectively.
• These values may be obtained from any of the above means (e.g., local manual or remote entry via UI/interface175) or from data encoded on one of the consumables involved in the process. For example, thefilter160, theRF fluid container147, the source fluid150 container (s), or any other consumable may be provided with one or more bar-codes, RFID tags, or other suitable encoding device. Such devices may provide values for T1 and T2, tables of values that depend upon other factors, or other data from which T1 and T2 may be derived.
• controller170 waits until it is time to start the flow of raw RF fluid from source fluid150 towardcontainer147 by comparing a current time (indicated by a clock internal to thecontroller170, which is not shown) to a difference between a scheduled treatment time and T1, which represents the lead time (ahead of the scheduled treatment) required for the filtering process. A loop through step S20 is exited to step S30 when the clock reaches the treatment time minus T1. At step S30, the flow of source fluid150 through thefilter160 is initiated. If thepump190 is present, it may be started and regulated according to a specified TMP. The latter may be provided to thecontroller170 manually or automatically through UI/interface175. Automatic entry may be by way of a data store such as bar-code or RFID attached to the filter, for example which may be read when thefilter160 is installed in a chassis with a corresponding reader device (not shown). Note, as mentioned above, the source fluid may be sterile and the filtration process provided as a guarantee against contamination, for example by accidental touching.
• Once the flow of source fluid150 is initiated, the controller waits for the required time for applying power to theheater185. The delay and the initiation are controlled by step S40 which is exited to step S50 only when the treatment time minus the predefined interval T2 is reached. As mentioned above, alternatively, the heater may be triggered by detecting fluid such as by means of a sensor (not shown) triggered by the presence ofsterile replacement fluid130 in thecontainer147. The sensor may be any of a variety of types, such as an ultrasonic sensor, capacitance sensor, mass sensor, optical sensor, etc.
• Once the heater is started, thecontroller170 may wait for the source fluid to be exhausted at step S60. Step S60 exits to step S70 when the source fluid is determined to be exhausted. The latter may be detected by integrating the flow rate to measure the total volume (the rate may be determined by the pumping rate, for example, or by a flow meter (not shown)). The exhaustion of the source fluid150 may also be indicated by a quantity indicator (e.g., a level indicator) in the sterile replacementfluid container147 or an intermediate container supplied through a drip chamber, for example. Alternatively, the exhaustion of thesource fluid150, if supplied from a fixed-volume container, may be indicated by a sensor such as an ultrasonic sensor, capacitance sensor, mass sensor, optical sensor, a scale, etc. Yet another alternative is to sense gas or a precipitous rise in negative pressure (sensed by a pressure sensor which is not shown) at thepump190 inlet. At step S70, theline120 may be clamped by actuating shutoff/control valve180. Additionally, if appropriate, thepump190 may be deactivated at the point where the exhaustion of thesource fluid150 is detected at step S70.
• According to an embodiment, as the fluid is pumped, the TMP of the filter, as indicated bypressure sensors162, may be monitored. If the TMP is determined by thecontroller170 to be, at any point, below a predetermined nominal value or to have changed precipitously during filtration, thecontroller170 may trigger an alarm or take some other action to insure that the resulting replacement fluid is handled appropriately. For example, a back-up filter could be added during treatment as discussed with respect toFIG. 5. The TMP results could trigger an alarm at any point during filtration or could be assessed and reported at step S70, before treatment would begin.
• Thecontroller170 pauses again at step S80 to wait for the sterile fluid to be exhausted. This may be indicated by a signal from the treatment machine (e.g., received via UI/interface175) or by direct measurement by a sensor, such as an ultrasonic sensor, capacitance sensor, mass sensor, optical sensor, a scale, etc. As mentioned above, thecontroller170, or theheater185 itself, may be provided with a threshold temperature-rise rate that indicates the mass of fluid in thereplacement fluid container147 has fallen below a minimum level. The loop of step S80 is exited to step S90 where power to theheater185 is terminated.
• Note that all the functionality attributed to thecontroller170 may be provided, via a control interface, by a controller (not shown) internal to a treatment machine. For example, the apparatus ofFIG. 1 could be provided as an optional module for such a treatment machine rather than a retrofit module.
• Referring now toFIG. 3, a combination blood treatment system and sterilereplacement fluid device310 has a replacementfluid preparation subsystem305 configured substantially as the device ofFIG. 1. Afilter260 filters fluid from a source offluid250 to generate a batch ofsterile replacement fluid230 as in the embodiment ofFIG. 1. Again, the source offluid150 may be a container of sterile or non-sterile replacement fluid, one or more containers of constituents which, when combined, form a proper replacement fluid and any of the latter may include a continuous source such as a water tap. Aline220 conveys the source fluid250 through thefilter260 and into abatch container247, which may be any type of sterile, preferably disposable container, for example, a large IV bag. It may also include a number of such containers appropriately interconnected to permit flow into and out of them in the fashion ofcontainer247.
• Again, apump290 may be provided and pressure at an outlet of thefilter260 may be sensed by apressure sensor262. Thepump290 may be controlled by acontroller270 to insure a maximum safe TMP to maximize throughput. Again, thepump290 is not required and the source fluid150 may be arranged such as to maintain a desired TMP at thefilter160 without the need of thepump290 orpressure sensor262 by elevation. Acontrol valve265 or a speed of thepump290 may be used to regulate the flow rate to maintain desired TMP limits.
• A control/shutoff valve280 may provide thecontroller270 the ability to stop the flow of fluid through thefilter260 once a desired volume is reached. Aheater285 may be provided to warm thesterile replacement fluid130 to prepare it for use. Aninsulated container245 may be used and the heater controlled as discussed with respect to theFIG. 1 embodiment. Bubbles may be controlled, as discussed above, by means of a vibration orultrasonic transducer230 as discussed above with regard to the previous embodiment.
• Aconnector295 may be provided for connecting the source fluid to theline220. The connector may be a luer, spike, threaded adapter, or any other suitable type. Although the various controls indicated above are shown to be controlled anautomatic controller270, each may be controlled also by manual mechanisms. Other aspects of the control mechanisms for the embodiment ofFIG. 3 may be provided as discussed with respect toFIGS. 1 and 2.
• The benefits of theFIG. 2 embodiment are similar to those of theFIG. 1 embodiment in that it allows replacement fluid over a time period that is not driven by the speed of supply to the treatment process. As a result, a low capacity filter may be used for thefilter260 with the attendant benefits identified above. Note that the UI/interface275 andcontroller270 are shared in the present embodiment by the treatment machine. Thus, any information required for control of both the treatment and preparation ofsterile replacement fluid230 would not need to be communicated to a separate controller such ascontroller170. Note also that the communications among the illustrated components is provided by achannel202 which may be wire harness, separate wires, a bus, a wireless channel or any suitable communications/power transmission device.
• In the embodiment ofFIG. 3, a predicted quantity of replacement fluid may be filtered and stored for use during treatment. If, however, for some reason, more is required, thetreatment machine controller270 could be configured to identify that situation and control thesubsystem305 components to provide it. Many blood treatment process employ afilter220 to filter blood and into which replacement fluid is supplied to apatient225. More details on preferred embodiments of the treatment machine are discussed below.
• In either of the above embodiments, the rate of flow of fluid during preparation of the batch of replacement fluid may be substantially less than the rate of consumption during treatment. In an exemplary embodiment of an application for hemofiltration, the amount of replacement fluid consumed is between 9 and 181. and the rate of consumption is approximately 200 ml./min. Also, the media used for sterile filtration may be any suitable media that insures the quality of the replacement fluid is as desired. In the embodiments discussed above, it was assumed that the end sought was preparation of sterile replacement fluid employed microfiltration to prevent the passage of pathogens. However, the invention could be used with other types of filtration or treatment processes to produce a batch of fluid consumed by a medical treatment process, for example, dialysate for hemodialysis treatment. The benefits accrue in particular when the time scale of preparation may be longer than the time scale of consumption. Moreover, the benefits are more appreciable when some sort of energy-consuming process is required, such as heating, before consumption.
• Here, not only is the time scale of preparation compatible with a small inexpensive filter, but the long time scale permits heating of the replacement fluid over a long interval. To support this benefit, the batch container may be insulated to minimize heat loss so a small heater will be adequate. Also, the preferred application for the present invention is in the context of hemofiltration because the quantity of fluid required for such treatment is relatively small.
• Note that other motivations for filtering the fluid, in addition to or as an alternative to sterilization of a non-sterile fluid, is (1) removal of air bubbles and/or (2) as a safety net for ensuring against accidental contamination. If bubble removal is the only concern, a drip chamber may be used instead of a filter. For removing bubbles, the filter preferably is of a type that permits the passage of fluid, but which blocks the passage of bubbles, for example due to its media pore size and the surface tension of the fluid.
• Referring now toFIG. 4A, a preferred type of filter for some of the present embodiments has aninlet port415 providing aninlet channel410 communicating with aninlet chamber440. Anoutlet leading port405 provides anoutlet channel420 communicating with anoutlet chamber445. A piece offilter media425 separates the inlet andoutlet chambers440 and445. The fluid to be sterilized enters theinlet chamber440, is sterilized by passing through thefilter media425, and exits via theoutlet chamber445. Agas relief gasket425 allows gas accumulating in theinlet chamber440 to be released to the ambient atmosphere.
• Internal supports and structural details are not shown in the illustration for clarity, but a practical embodiment of the filter ofFIG. 4 may have ribs for strength and internal supports for themedia425 andgasket425 so that thefilter400 may be capable of tolerating a substantial TMP.
• Thegas relief gasket425 may be of a porous hydrophobic material such as PTFE. Air bubbles trapped in theinlet chamber440 can coalesce in theinlet chamber440 and exit via theair relief gasket425. It may be, depending on the type ofgas relief gasket425 used, that a substantial TMP will be required to eliminate air.
• An alternative to thegas relief gasket425 is agas relief valve426 as shown inFIG. 4B. Since theinlet chamber440 is connected to the non-sterile side of the filtration system, there is little risk of contamination if microbes were to enter through a mechanical device such as thegas relief valve426. The latter is illustrated figuratively and allows only gas to escape. Other features of the embodiment ofFIG. 4B are labeled with the same numerals as features of the embodiment ofFIG. 4A where they serve substantially identical functions and, thus, their descriptions are not repeated here.
• Referring now toFIG. 5, the filters ofFIGS. 4A and 4B may be used for filtration of replacement fluid in the embodiment ofFIG. 5 as discussed presently.
• Replacement fluid360, which may or may not be sterile, is supplied to ahemofiltration machine490. Areplacement fluid pump360 pumps the replacement fluid into abalancing mechanism330 which meters the replacement fluid before it is introduced, via ajunction485, into the venous (return)line480 and ultimately into the blood stream of apatient225. Waste fluid is drawn through awaste line470 from afilter395 and pumped via awaste pump365 through thefluid balancing mechanism330. Thefluid balancing mechanism330 meters the replacement fluid to match the rate of withdrawal of waste fluid so that the patient's fluid balance is maintained during treatment. Actually, the rate of withdrawal of waste fluid may be less than the rate of metering of replacement fluid by pumping waste fluid through a bypass pump called anultrafiltration pump339. The latter sends some of the waste fluid directly to awaste fluid sump380, thereby bypassing thefluid balancing mechanism330. The fluid balancing mechanism is depicted figuratively and may operate in accord with any suitable control device. Preferably it meters replacement fluid on an equal- volume or equal-mass basis. A preferred mechanism is described in U.S. patent application Ser. No. 09/513,911, filed Feb. 25, 2000, entitled:“Synchronized Volumetric Fluid Balancing Systems and Methods,” which is hereby incorporated by reference as if fully set forth in its entirety herein. Various sensors and line clamps, indicated figuratively at335,355,320,385, and390, may be provided to control flow and ensure safe operation.
• Afilter337, is provided in thereplacement fluid line338 just upstream of thejunction485. Thefilter337 may serve as a last chance safety net for ensuring that replacement fluid is sterile and/or that all bubbles are removed before flowing into thevenous line480. To ensure that air is not infused into the patient's body, anair sensor390 is often provided in hemofiltration systems, but detection of air normally triggers an alarm, automatic shutdown, and skilled intervention to restart the hemofiltration treatment. Obviously, this is undesirable so the system should, as effectively as possible, insure that air or other gas is not injected into thevenous line480.
• Although in the embodiment ofFIG. 5, a hemofiltration machine was discussed, other types of treatment processes may be provided a last-chance filter similar to filter337. For example, hemodiafiltration, hemodialysis, or other treatments may require the infusion of replacement fluid and thereby benefit from a filter such asfilter337. Preferably, thefilter337 is substantially as in the embodiment ofFIG. 4A. Thus, thefilter337 removes both air and pathogens.
• Instead of employing a filter at the location indicated at337, a drip chamber may be used. Suitable drip chambers are currently available with air vents and microfilters effective to remove pathogens, so they may be substituted for thefilter337. Also, in some cases, it may be that there is very little risk that the replacement fluid is contaminated with pathogens, thefilter337 may serve as a mechanism for removing only air or other gases. In such cases, drip chambers which remove gas (either with or without a vent), could be employed at the above location in the fluid circuit.
• Referring now toFIGS. 6,7, and8 the last chance filter or drip chamber (or combination device)510 may be installed in acartridge520 that holds and orients blood and fluid circuits for ahemofiltration machine540. In the embodiment shown, which is described substantially in U.S. patent application Ser. No. 09/513, 773 filed Feb. 25, 2000 and entitled: “Fluid Processing Systems and Methods Using Extracorporeal Fluid Flow Panels Oriented Within A Cartridge,” hereby incorporated by reference in its entirety as if fully set forth herein, fluid circuit components may be held in acartridge520 and clamped (as shown inFIG. 8 with the machine closing as illustrated by the arrow665) within a receivinggap530 in a blood treatment machine such ashemofiltration machine540. Thecartridge520 may have a preferred orientation which may insure a correct orientation for the last chance filter or drip chamber (or combination device)510 if required by the particular device chosen. To insure orientation of the last chance filter or drip chamber (or combination device)510, the latter is preferably held by thecartridge520 in a fixed orientation with respect to thecartridge520.
• In an alternative embodiment, the last chance filter or drip chamber (or combination device)520 may be accompanied by adevice660 for measuring the quality of the replacement fluid, such as conductivity or density. This may provide a last-chance check that the replacement fluid is of the correct type. For example, where such fluids are derived from mixtures, if the proportion is not exactly what is required, infusion could be harmful to thepatient225. An example of adevice660 to test the fluid could be a wettable pair of contacts (not shown) formed in atubing set650 of the cartridge may be used in conjunction with a resistance measurement device to measure the ion concentration of the fluid. Alternatively, a non-wettable sensor, such as an ultrasonic conductivity cell could be used. Other kinds of fluid quality sensors could be employed such as new types of specific-molecule detectors built on silicon wafers.
• Preferably, the tubing set650 andcartridge620 of which it is a part form a disposable component that is used for one treatment and disposed of. Note that thefluid quality sensor660 may used alone or together with the last chance filter or drip chamber (or combination device)510. Note, althoughFIGS. 6 and 7 are detailed, they are intended to show various components figuratively and do not reveal the details of the routing necessary to achieve the flow paths discussed with respect to them or as illustrated elsewhere.
• Referring now also toFIG. 9, the tubing set andcartridge assembly610, discussed previously, may incorporate the batch replacementfluid container625 as part of a sterilereplaceable set690. Thefilter615 may have atube622 with aconnector620 for attachment to asource fluid250. Atube635 may connect the filter to the batch replacementfluid container625, which may be fitted with anothertube630 to convey fluid to the tubing set andcartridge assembly610. Referring now also toFIG. 10, the batch replacementfluid container625 may also be fitted withadditional connectors670 and/or extensions (not shown) to permit the batch replacement fluid container to be used for priming blood, replacement fluid, and/or waste lines. For example, as discussed in U.S. patent application Ser. No. 09/905,246, filed Jul. 12, 2001, entitled: “Devices and Methods For Sterile Filtering of Dialysate,” which is hereby incorporated by reference as if fully set forth in its entirety herein, replacement fluid is circulated through areplacement fluid container740 to flush air out of all the fluid circuiting (not all shown) of a blood treatment apparatus710. As described in detail in the '246 application incorporated by reference above, the venous (return) and arterial (supply)blood lines725 and730 may be temporarily connected viaconnectors750 to thereplacement fluid container740 and fluid circulated through thecontainer740 until gas bubbles are substantially purged from the relevant circuits.
• Note, thereplacement fluid container740 corresponds to the containers147 (FIG. 1),247 (FIGS. 3), and625 (FIG. 9) in the foregoing figures and to respective containers in the application incorporated by reference immediately above. The air and other gases may settle in thereplacement fluid container740 as the fluid circulates. Liberation of the gases would ordinarily be promoted by the application of heat from a heater775 (with power source770), which may be employed as discussed with regard to the embodiments ofFIGS. 1-3 or in any suitable way to bring the temperature of the replacement fluid to body temperature. Replacement fluidcircuits including line735, bloodcircuits including lines725 and730, and waste fluidcircuits including line780 may all be flushed with fluid from thecontainer740. The details of the blood treatment apparatus and its internal plumbing can vary. Replacement fluid may be transferred from thereplacement fluid line735 or from theblood line735 to the waste line, for example through a filter, to flush the waste portion of the circuit including thewaste line780. Replacement fluid may circulate through the bloodcircuit including lines725 and730 as indicated to flush the blood circuit, at least a portion of which may be closed as indicated by the arterial andvenous lines730 and735.
• Disposable components, such as the circuit sets ofFIGS. 8 and 9 or the batch replacementfluid container625 alone, or other components that may be used with the embodiments disclosed may be packaged with instructions for preparing infusible replacement fluid. For example, the source fluid150/1250 or a concentrate which may be mixed to make the same (FIGS. 1 and 3) may be supplied with instructions for sterile filtering the fluid as described in the instant specification. Such may constitute packages of consumables or reusable components.
• Note that benefits of the filtering method and apparatus discussed above may best be achieved by performing the filtration just prior to treatment, although this is not required. The filtering method may be performed at the treatment site. For example, non-sterile concentrate may be stored at the residence of a patient.
• The concentrate may be diluted with distilled water in a source fluid container (e. g.,196 ofFIG. 1) at the residence and processed as discussed in the instant application.
• Because the infusible fluid is generated at the treatment site, the need for regulatory-cleared fluids, such as might be obtained from a manufacturer, is not avoided. Cost savings and storage-space economies can thus be realized by the patient. This is particularly important in view of the fact that renal replacement therapies are often administered many times per week and storage and cost of consumables can present a serious problem in a residence or any other facility.
• Referring now toFIG. 11, a blood treatment machine, a portion of which is illustrated figuratively at810, may permit apump845 that, during treatment, conveys replacement fluid to a patient, to be used for filtering a sterile filtering a non- sterile source fluid. Here, themachine810 has acommon guide850 that accommodates afluid line815 through which fluid is conveyed by thepump845, for example a peristaltic pump. During treatment, the line815-825 may be guided by a firstselected guide830 in a first direction toward other components of an internal fluid circuit (not shown) as indicated at825. During sterile-filtering, fluid may be pumped by thesame pump845 through a line815-820 that is allowed to pass out of theblood treatment machine810 via adifferent guide835. This allows the line815-820 to be fed to an external connection to the sterile fluid container (not shown) as indicated at820.
• Referring now toFIG. 12, another embodiment of a replacement fluid container portion of a disposable tubing set includes areplacement fluid container1, a break-off femaleluer lock connector4, a y-connector,5, apinch clamp6, amale luer8, afemale luer26, a 0.22 micron poreanti pyrogen filter11, a nonreopenable tubing clamp13, anon-breathing cap14 on afemal luer9, an in-line check valve16, apinch clamp18, a break-off male luer cap andfemale luer19, and afemale luer21 andtubing branches3,7,10,12,15,17, and20. Thereplacement fluid container1 is delivered to a patient treatment setting as a sealed sterile container with all terminals sealed. The replacement fluid container contains, as delivered, a concentrate solution sufficient to create a treatment batch of replacement fluid when water is added.
• Concentrate may be added by means of theluer connector21. In the deliverable to the treatment site, thetubing branch20 may be sealed and cut after the concentrate is added. Water is added at the treatment site through connection to a water source vialuer19. The water is preferably metered to provide a predefined quantity. The 0.22 micron filter is sufficient to protect against contamination before water is added to thereplacement fluid container1. A sample of diluted replacement fluid may be drawn through theluer19 before treatment. Thecheck valve16 prevents any contamination due to backflow from the sampling procedure. After water is added to thereplacement fluid container1, theluer9 is disconnected from themale luer8 and the male luer connector connected to the blood treatment system.
• To supply suitable water that is substantially free of unwanted dissolved and undissolved materials, a combination of permanent and replaceable components may be provided at the treatment site.FIG. 13 illustrates such a set up in overview fashion. Apretreatment module900 provides primary filtration from a raw water supply, for example tap water and feeds prefiltered water to acontroller module905 which provides various control functions, a pump, pressure detection and control, and permanent filtering capabilities which are not shown separately here. Water is metered by the control module into a consumabledisposable module910 which may provide deionization, adsorption filtration, microporous filtering, chemical pretreatment, etc. and any other types of filtering that may require replacement of components. The purified water is finally conveyed to the replacementfluid container circuit915 discussed with reference toFIG. 12.
• Referring toFIG. 14,pretreatment module900 is shown in more detail. Acheck valve955 prevents backflow. Anair vent953 removes air from the primary supply and a sediment filter951 (which may be replaceable) provides substantial filtering of solids.
• Referring toFIG. 15, thecontrol module905 is shown in greater detail. Ashutoff valve1010 is provided for safety.Pressure indicators1015 and1025 may be provided for monitoring the respective pressures in and out of apump1020.
• Feedback regulation may be provided to ensure that consistent metering is provided if the pump is relied upon for measuring the total quantity of water supplied to thereplacement fluid container1. A high intensity ultraviolet (UV)lamp1030 provides a sterilization mechanism. Preferably, theUV lamp1030 is ov such intensity and wavelength as to provide disintegration of chloramines. In a preferred embodiment, the lamp is characterized by a 245 nm wavelength and an output power of 750 mJ/cm2 up to 1500 mJ/cm2 which is sufficient to remove chloramines.
• Referring toFIG. 16, the replaceable (disposable or remanufacturable)filter module910 contains afirst stage filter1007 copper-zinc alloy which is used to subject the water to a reduction/oxidation process to remove ions. This removes ions through a chemical reaction. An embodiment is KDF 85 media where about on pound is used for a flow rate of 150 ml./min water flow rate. A activatedcarbon filter1005 follows which is a well-known adsorption type filter. Next three stages ofstrong acid cation1011 andstrong base anion1009 filters follow in series. Asensor1022 detects ion concentration by contact testing of the conductivity of the water. A signal is generated to indicate that this is the last allowed batch before replacement of thereplaceable module910. A mixedbed deionoization filter1030 is provided next and a safeguard conductivity test is provided with an audible alarm at1025 as a back up safety measure. If the conductivity it detects is above a certain level, thepump1020 may be shut off and an alarm sounded. This may come into play if an operator ignores thetester1022 which may provide a visual signal or if thetester1022 fails.
• TP is a hydrophobic membrane air vent which allows air in anultrafilter1035 to be purged. Theultrafitler1035 may be a microtubular filter such as used for dialysis. A 1.2 micron air vent may also be provided as shown at1047.
• Note the final conductivity sensor/alarm1025 may control the pump, as noted. Acontroller1090 may be connectable to thedisposable filter module910 and configured to stop thepump1020. The trigger resistivity safety level to cut-off thepump1020 may be 1 megaohm, but may be raised to 2 megohm to allow the use of required temperature compensated resistivity probes (an FDA & AAMI requirement) This does allow use of low cost in-line resistivity probes in thedisposable filter module910.
• The following is a procedure for using the above devices discussed with reference toFIGS. 12-16.
• 1. Remove the dialysate concentrate tubing set915 and remove thecap14 from thetubing line7 that contains thefilter11. (The 0.22micron filter11 provides additional protection from inadvertent contamination.)
• 2. Connect the water source to the concentratebag luer connection9.
• 3. Break thefrangible luer connector4 which connector is configured to form a permanent seal on the side facing the Y-junction5 when disconnected.
• 4. Add 3 liters of water into the concentrate bag using the purification plant throughtubing branch7 throughluer connector9.
• 5. Write on the bag label the date and time water was first added to the concentrate bag, to assist in ensuring that it is used within 24 hours.
• 6. Shake thereplacement fluid container1 well to mix.
• 7. Confirm solution conductivity prior to use. Remove the break-offcap1 and draw sample from thisbranch16. After removing the sample, clamp the line using thepinch clamp18 provided.
• 8. (The following is normative according to a preferred embodiment and not limiting of the invention) Conductivity must be in the range 13.0 to 14.4 mS.
• Nominal conductivity for the dialysate solution is 13.7 mS at 25 C. If conductivity does not meet this specification do not use it. Verify that the results are accurate. If conductivity is high additional water may be added to bring it within specification. If conductivity is low then the solution must be discarded.
• 9. Using thenon re-opening clamp13 provided, clamp the line that is connected to the water purification plant.
• 10. Using theclamp6 is next clamped on the line that is connected to thedialysate bag1.
• 11. Disconnect the water source at theluer connection26
• 12. Connect the bag of dialysate solution to the dialysis circuit at theconnection8. This leaves thefilter11 andpermanent clamp13 in place to protect the water supply source.
• 13. Unclamp the line going to the dialysate bag (red clamp), and initiate treatment after verifying that dialysate will be used within 24 hours from when water was added.
• Although the foregoing invention has, for the purposes of clarity and understanding, been described in some detail by way of illustration and example, it will be obvious that certain changes and modifications may be practiced that will still fall within the scope of the appended claims. For example, the devices and methods of each embodiment can be combined with or used in any of the other embodiments.

Claims (5)

1. (canceled)

2. A device for preparing replacement fluid for an extracorporeal blood treatment, comprising:

a replaceable fluid circuit including a sealed pre-sterilized replacement fluid container, which contains a replacement fluid concentrate, and a port that allows diluting water to be added to said replacement fluid concentrate by passing through said port; and

a water treatment plant connectable to said replaceable fluid circuit for supplying water to the port, said water treatment plant having a permanent component including a metering pump and a replaceable module configured to decontaminate water provided to the plant from a source.

3. The device according toclaim 2, wherein the replaceable filter module comprises a first stage filter for subjecting the water to a reduction/oxidation process to remove ions, followed by an adsorption filter, followed by stages of strong acid cation and strong base anion filters, followed by a mixed bed deionization filter, followed by a microtubular ultrafilter.

4. The device according toclaim 3, further comprising a sensor detecting ion concentration by contact testing of the conductivity of the water, wherein a signal is generated indicating the last allowed batch before replacement of the replaceable module.

5. The device ofclaim 2, further comprising a microporous filter, the port being configured such that the diluting water to be added to said replacement fluid concentrate passes through said microporous filter.

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