US 20080053905 A9
A method and device for blood treatments that use fluids such as dialysate and replacement fluid for renal replacement therapy. In an embodiment, fluid is passed either by pump or passively by gravity feed, through a microporous sterilization filter from a fluid source to a replacement fluid container. The latter forms a batch that may be used during treatment. The advantage of forming the batch before treatment is that the rate of filtering needn't match the rate of consumption during treatment. As a result, the sterilization filter can have a small capacity. In another embodiment, a filter is placed immediately prior to the point at which the sterile fluid is consumed by the treatment process. The latter may be used in combination with the former embodiment as a last-chance guarantee of sterility and/or that the fluid is free of air bubbles. It may also be used as the primary means of sterile-filtration.
1. A method of administering a renal replacement therapy requiring a sterile fluid, comprising the steps of: at least one of carbon-filtering, deionizing, and ultra-filtering water to produce a source fluid; sterile-filtering the source fluid to generate a sterile fluid; flowing said sterile fluid into a sterile batch container; said steps of sterile-filtering and flowing including performing said steps at a location and time at which a patient is to be treated using sterile fluid from the batch container; and flowing said sterile fluid from said sterile batch container to a treatment system, wherein at least one of said steps of sterile-filtering and flowing includes automatically controlling at least one of a flow rate of said sterile fluid and a rate of heating of said sterile fluid responsively to data representing at least one of a statement start time and a volume of said fluid infusible fluid required for a treatment.
2. A method of administering a rental replacement therapy requiring a sterile fluid, comprising:
deionizing water to generate a source fluid;
sterile-filtering the source fluid to generate sterile water, the sterile-filtering include passing the water through an ultrafilter;
flowing the sterile water into a sterile batch container that contains dialysate concentrate to produce a solution;
the sterile-filtering and flowing including performing the steps at a location and time at which a patient is to be treated using the solution; and
flowing the solution from the sterile batch container to a treatment system, wherein the sterile-filtering includes automatically controlling a flow volume responsively to a treatment start time, a volume of the solution required for a treatment, and a required concentration of the solution.
3. The method of
4. The method of
5. The method of
6. The method of
7. The method of
8. The method of
9. The method of
10. The method of
11. The method of
12. A method of administering a renal replacement therapy requiring a sterile fluid, comprising:
deionization-filtering water to produce deionized water;
ultrafiltering the deionized water to generate purified water;
providing a sterile batch container containing a predefined quantity of concentrate;
flowing the purified fluid into the batch container to generate a solution;
storing the solution in the batch container;
the filtering, providing, and flowing being done at a location and time at which a patient is to be treated using the solution; and
flowing the solution from the sterile batch container to a treatment system;
wherein the flowing of the purified fluid into the batch container includes automatically controlling a flow rate responsively to data representing a volume of the fluid infusible fluid required for a treatment.
13. The method of
14. The method of
15. The method of
16. The method of
17. The method of
18. The method of
19. The method of
20. The method of
21. The method of
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.
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.
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 of container 147.
Included in the conveyance from source fluid 150 to sterile replacement fluid 130 may be a pump 190, such as a peristaltic pump. The pressure at an outlet of the filter 160 may be sensed by a pressure sensor 162 and the pump 190 controlled by a controller 170 to insure a predefined transmembrane pressure (TMP) threshold of the filter 160 is not breached. The TMP may be maintained at a maximum safe level to maximize throughput. Note that complexity may be avoided if the source fluid 150 is arranged such as to maintain a desired TMP at the filter 160 without the need of a pump 190 or pressure sensor 162. For example, the source fluid 150 may be provided by a batch container elevated at a certain height to provide a desired head. Note that a control valve 165 or a speed of the pump 190 may be used to regulate the flow rate to maintain desired TMP limits.
A control/shutoff valve 180 may provide the controller 170 the ability to stop the flow of fluid through the filter 160 once a desired volume is reached. A heater 185 may be provided to warm the sterile replacement fluid 130 to prepare it for use. An insulated container 145 may be used to reduce heat loss so that heater 185 can be a relatively low power type. The heater 185 may be controlled by the controller 170 to ensure the replacement fluid 130 is at a desired temperature when required to be used. Alternatively the heater 185 can be controlled by an independent device actuated by, for example, a pressure sensor (not shown) triggered by the flow of fluid into the batch container 147, 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., a temperature sensor 183 combined with logic in controller 170) regulates power to the heater to ensure a required temperature is maintained and not exceeded. The temperature sensor 183 may be used to sense the quantity of sterile replacement fluid by the rate of detected temperature increase versus heater output. The temperature sensor 183, heater 185, and sterile replacement fluid 130 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, the controller 170 may be programmed to respond in accord with the assumption the sterile RF is exhausted. Equivalently, the controller 170 may simply respond to some predefined rate of temperature rise of the temperature sensor 183.
When the temperature of the sterile replacement fluid 130 is raised, dissolved gas may come out of solution. This may cause bubbles to accumulate inside the replacement fluid container 247, 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 provided 183 to cause bubbles to coalesce and rise to a top of the container 147. As a result, bubble-free replacement fluid may be drawn through the outlet 148.
A connector 195 may be provided for connecting the source fluid to the line 120. 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 an automatic controller 170, each may be controlled also by manual mechanisms.
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 of
Referring now to
These values may be obtained from any of the above means (e.g., local manual or remote entry via UI/interface 175) or from data encoded on one of the consumables involved in the process. For example, the filter 160, the RF fluid container 147, the source fluid 150 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.
The controller 170 waits until it is time to start the flow of raw RF fluid from source fluid 150 toward container 147 by comparing a current time (indicated by a clock internal to the controller 170, 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 fluid 150 through the filter 160 is initiated. If the pump 190 is present, it may be started and regulated according to a specified TMP. The latter may be provided to the controller 170 manually or automatically through UI/interface 175. 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 the filter 160 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 fluid 150 is initiated, the controller waits for the required time for applying power to the heater 185. 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 of sterile replacement fluid 130 in the container 147. 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, the controller 170 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 fluid 150 may also be indicated by a quantity indicator (e.g., a level indicator) in the sterile replacement fluid container 147 or an intermediate container supplied through a drip chamber, for example. Alternatively, the exhaustion of the source fluid 150, 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 the pump 190 inlet. At step S70, the line 120 may be clamped by actuating shutoff/control valve 180. Additionally, if appropriate, the pump 190 may be deactivated at the point where the exhaustion of the source fluid 150 is detected at step S70.
According to an embodiment, as the fluid is pumped, the TMP of the filter, as indicated by pressure sensors 162, may be monitored. If the TMP is determined by the controller 170 to be, at any point, below a predetermined nominal value or to have changed precipitously during filtration, the controller 170 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 to
The controller 170 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/interface 175) or by direct measurement by a sensor, such as an ultrasonic sensor, capacitance sensor, mass sensor, optical sensor, a scale, etc. As mentioned above, the controller 170, or the heater 185 itself, may be provided with a threshold temperature-rise rate that indicates the mass of fluid in the replacement fluid container 147 has fallen below a minimum level. The loop of step S80 is exited to step S90 where power to the heater 185 is terminated.
Note that all the functionality attributed to the controller 170 may be provided, via a control interface, by a controller (not shown) internal to a treatment machine. For example, the apparatus of
Referring now to
Again, a pump 290 may be provided and pressure at an outlet of the filter 260 may be sensed by a pressure sensor 262. The pump 290 may be controlled by a controller 270 to insure a maximum safe TMP to maximize throughput. Again, the pump 290 is not required and the source fluid 150 may be arranged such as to maintain a desired TMP at the filter 160 without the need of the pump 290 or pressure sensor 262 by elevation. A control valve 265 or a speed of the pump 290 may be used to regulate the flow rate to maintain desired TMP limits.
A control/shutoff valve 280 may provide the controller 270 the ability to stop the flow of fluid through the filter 260 once a desired volume is reached. A heater 285 may be provided to warm the sterile replacement fluid 130 to prepare it for use. An insulated container 245 may be used and the heater controlled as discussed with respect to the
A connector 295 may be provided for connecting the source fluid to the line 220. 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 an automatic controller 270, each may be controlled also by manual mechanisms. Other aspects of the control mechanisms for the embodiment of
The benefits of the
In the embodiment of
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 to
Internal supports and structural details are not shown in the illustration for clarity, but a practical embodiment of the filter of
The gas relief gasket 425 may be of a porous hydrophobic material such as PTFE. Air bubbles trapped in the inlet chamber 440 can coalesce in the inlet chamber 440 and exit via the air relief gasket 425. It may be, depending on the type of gas relief gasket 425 used, that a substantial TMP will be required to eliminate air.
An alternative to the gas relief gasket 425 is a gas relief valve 426 as shown in
4B are labeled with the same numerals as features of the embodiment of
Referring now to
Replacement fluid 360, which may or may not be sterile, is supplied to a hemofiltration machine 490. A replacement fluid pump 360 pumps the replacement fluid into a balancing mechanism 330 which meters the replacement fluid before it is introduced, via a junction 485, into the venous (return) line 480 and ultimately into the blood stream of a patient 225. Waste fluid is drawn through a waste line 470 from a filter 395 and pumped via a waste pump 365 through the fluid balancing mechanism 330. The fluid balancing mechanism 330 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 an ultrafiltration pump 339. The latter sends some of the waste fluid directly to a waste fluid sump 380, thereby bypassing the fluid balancing mechanism 330. 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 at 335,355, 320,385, and 390, may be provided to control flow and ensure safe operation.
A filter 337, is provided in the replacement fluid line 338 just upstream of the junction 485. The filter 337 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 the venous line 480. To ensure that air is not infused into the patient's body, an air sensor 390 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 the venous line 480.
Although in the embodiment of
Instead of employing a filter at the location indicated at 337, 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 the filter 337. Also, in some cases, it may be that there is very little risk that the replacement fluid is contaminated with pathogens, the filter 337 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 to
In an alternative embodiment, the last chance filter or drip chamber (or combination device) 520 may be accompanied by a device 660 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 the patient 225. An example of a device 660 to test the fluid could be a wettable pair of contacts (not shown) formed in a tubing set 650 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 set 650 and cartridge 620 of which it is a part form a disposable component that is used for one treatment and disposed of. Note that the fluid quality sensor 660 may used alone or together with the last chance filter or drip chamber (or combination device) 510. Note, although
Referring now also to
Note, the replacement fluid container 740 corresponds to the containers 147 (
Disposable components, such as the circuit sets of
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 of
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 to
Referring now to
Concentrate may be added by means of the luer connector 21. In the deliverable to the treatment site, the tubing branch 20 may be sealed and cut after the concentrate is added. Water is added at the treatment site through connection to a water source via luer 19. 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 the replacement fluid container 1. A sample of diluted replacement fluid may be drawn through the luer 19 before treatment. The check valve 16 prevents any contamination due to backflow from the sampling procedure. After water is added to the replacement fluid container 1, the luer 9 is disconnected from the male luer 8 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.
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 the replacement fluid container 1. A high intensity ultraviolet (UV) lamp 1030 provides a sterilization mechanism. Preferably, the UV lamp 1030 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.
1022 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 the replaceable module 910. A mixed bed deionoization filter 1030 is provided next and a safeguard conductivity test is provided with an audible alarm at 1025 as a back up safety measure. If the conductivity it detects is above a certain level, the pump 1020 may be shut off and an alarm sounded. This may come into play if an operator ignores the tester 1022 which may provide a visual signal or if the tester 1022 fails.
TP is a hydrophobic membrane air vent which allows air in an ultrafilter 1035 to be purged. The ultrafitler 1035 may be a microtubular fitler such as used for dialysis. A 1.2 micron air vent may also be provided as shown at 1047.
Note the final conductivity sensor/alarm 1025 may control the pump, as noted. A controller 1090 may be connectable to the disposable filter module 910 and configured to stop the pump 1020. The trigger resistivity safety level to cut-off the pump 1020 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 resisitivity probes in the disposable filter module 910.
The following is a procedure for using the above devices discussed with reference to
1. Remove the dialysate concentrate tubing set 915 and remove the cap 14 from the tubing line 7 that contains the filter 11. (The 0.22 micron filter 11 provides additional protection from inadvertent contamination.)
2. Connect the water source to the concentrate bag luer connection 9.
3. Break the frangible luer connector 4 which connector is configured
to form a permanent seal on the side facing the Y-junction 5 when disconnected.
4. Add 3 liters of water into the concentrate bag using the purification plant through tubing branch 7 through luer connector 9.
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 the replacement fluid container 1 well to mix.
7. Confirm solution conductivity prior to use. Remove the break-off cap 1 and draw sample from this branch 16. After removing the sample, clamp the line using the pinch clamp 18 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 the non re-opening clamp 13 provided, clamp the line that is connected to the water purification plant.
10. Using the clamp 6 is next clamped on the line that is connected to the dialysate bagl.
11. Disconnect the water source at the luer connection 26
12. Connect the bag of dialysate solution to the dialysis circuit at the connection 8. This leaves the filter 11 and permanent clamp 13 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.