Abstract:
A medical machine includes: an enclosure defining an opening, at least a portion of the enclosure being electrically conductive and acting as a first capacitor plate; a medical device component located inside the enclosure; a window placed adjacent to the opening; a video display with an at least partially conductive case acting as a second capacitor plate; and a dielectric member placed between the first and second capacitor plates, the plates and dielectric member forming a capacitor configured to prevent leakage of electromagnetic energy from the enclosure.

Description:
BACKGROUND 
       [0001]    In general, the present disclosure relates to medical fluid delivery systems that employ a pumping cassette. In particular, the present disclosure provides systems, methods and apparatuses for cassette-based dialysis medical fluid therapies, including but not limited to those using peristaltic pumps and diaphragm pumps. 
         [0002]    Due to various causes, a person&#39;s renal system can fail. Renal failure produces several physiological derangements. The balance of water, minerals and the excretion of daily metabolic load is no longer possible and toxic end products of nitrogen metabolism (urea, creatinine, uric acid and others) can accumulate in blood and tissue. 
         [0003]    Kidney failure and reduced kidney function have been treated with dialysis. Dialysis removes waste, toxins and excess water from the body that would otherwise have been removed by normal functioning kidneys. Dialysis treatment for replacement of kidney functions is critical to many people because the treatment is life-saving. 
         [0004]    Hemodialysis and peritoneal dialysis are two types of dialysis therapies used commonly to treat loss of kidney function. Hemodialysis treatment utilizes the patient&#39;s blood to remove waste, toxins and excess water from the patient. The patient is connected to a hemodialysis machine and the patient&#39;s blood is pumped through the machine. Catheters are inserted into the patient&#39;s veins and arteries so that blood can flow to and from the hemodialysis machine. The blood passes through a dialyzer of the machine, which removes waste, toxins and excess water from the blood. The cleaned blood is returned to the patient. A large amount of dialysate, for example about 120 liters, is consumed to dialyze the blood during a single hemodialysis therapy. Hemodialysis treatment lasts several hours and is generally performed in a treatment center about three or four times per week. 
         [0005]    Peritoneal dialysis uses a dialysis solution, or “dialysate,” which is infused into a patient&#39;s peritoneal cavity via a catheter. The dialysate contacts the peritoneal membrane of the peritoneal cavity. Waste, toxins and excess water pass from the patient&#39;s bloodstream, through the peritoneal membrane and into the dialysate due to diffusion and osmosis, i.e., an osmotic gradient occurs across the membrane. The spent dialysate is drained from the patient, removing waste, toxins and excess water from the patient. This cycle is repeated. 
         [0006]    There are various types of peritoneal dialysis therapies, including continuous ambulatory peritoneal dialysis (“CAPD”), automated peritoneal dialysis (“APD”), tidal flow APD and continuous flow peritoneal dialysis (“CFPD”). CAPD is a manual dialysis treatment. The patient manually connects an implanted catheter to a drain, allowing spent dialysate fluid to drain from the peritoneal cavity. The patient then connects the catheter to a bag of fresh dialysate, infusing fresh dialysate through the catheter and into the patient. The patient disconnects the catheter from the fresh dialysate bag and allows the dialysate to dwell within the peritoneal cavity, wherein the transfer of waste, toxins and excess water takes place. After a dwell period, the patient repeats the manual dialysis procedure, for example, four times per day, each treatment lasting about an hour. Manual peritoneal dialysis requires a significant amount of time and effort from the patient, leaving ample room for improvement. 
         [0007]    Automated peritoneal dialysis (“APD”) is similar to CAPD in that the dialysis treatment includes drain, fill, and dwell cycles. APD machines, however, perform the cycles automatically, typically while the patient sleeps. APD machines free patients from having to manually perform the treatment cycles and from having to transport supplies during the day. APD machines connect fluidly to an implanted catheter, to a source or bag of fresh dialysate and to a fluid drain. APD machines pump fresh dialysate from a dialysate source, through the catheter, into the patient&#39;s peritoneal cavity, and allow the dialysate to dwell within the cavity, and allow the transfer of waste, toxins and excess water to take place. The source can be multiple sterile dialysate solution bags. 
         [0008]    APD machines pump spent dialysate from the peritoneal cavity, though the catheter, to the drain. As with the manual process, several drain, fill and dwell cycles occur during APD. A “last fill” occurs at the end of CAPD and APD, which remains in the peritoneal cavity of the patient until the next treatment. 
         [0009]    Both CAPD and APD are batch type systems that send spent dialysis fluid to a drain. Tidal flow systems are modified batch systems. With tidal flow, instead of removing all of the fluid from the patient over a longer period of time, a portion of the fluid is removed and replaced after smaller increments of time. 
         [0010]    Continuous flow, or CFPD, systems clean or regenerate spent dialysate instead of discarding it. The systems pump fluid into and out of the patient, through a loop. Dialysate flows into the peritoneal cavity through one catheter lumen and out another catheter lumen. The fluid exiting the patient passes through a reconstitution device that removes waste from the dialysate, e.g., via a urea removal column that employs urease to enzymatically convert urea into ammonia. The ammonia is then removed from the dialysate by adsorption prior to reintroduction of the dialysate into the peritoneal cavity. Additional sensors are employed to monitor the removal of ammonia. CFPD systems are typically more complicated than batch systems. 
         [0011]    Hemodialysis, APD (including tidal flow) and CFPD systems can employ a pumping cassette. The pumping cassette typically includes a flexible membrane that is moved mechanically to push and pull dialysis fluid out of and into, respectively, the cassette. Certain known systems include flexible sheeting on one side of the cassette, while others include sheeting on both sides of the cassette. Positive and/or negative pressure can be used to operate the pumping cassettes. 
         [0012]    As described herein, the present disclosure provides a number of improvements to such fluid delivery systems. 
       SUMMARY 
       [0013]    A first aspect of the embodiments described herein includes improved product configurations. Here, different parts of the cassette-based peritoneal dialysis system are configured advantageously, such as: (i) operational placement of the system; (ii) user interface configuration and orientation; (iii) disposable cassette loading; (iv) cassette/heater and bag/tube management; (v) solution bag configuration; (vi) drain bag configuration; and (vii) storage and supply organization. 
         [0014]    An second aspect of the embodiments described herein includes a capacitance electromagnetic compliance (“EMC”) seal for the display of the user interface of the dialysis system. The seal as seen below does not cover the viewable portion of the display, improving light transmittance and image quality versus known seals. 
         [0015]    A third aspect of the embodiments described herein includes an elastomeric keypad for use with the display of the user interface of the dialysis system. The keypad, among other features, includes an ambient light sensor that provides a signal output, which is used to control adjustment of display brightness and contrast based on a change in ambient light. 
         [0016]    A fourth aspect of the embodiments described herein includes a low battery disconnect circuit for the dialysis system. The circuit allows the battery back-up disconnect voltage to be set closer to the regulated voltage, enabling the dialysis system to operate longer on battery back-up power. 
         [0017]    A fifth aspect of the embodiments described herein includes an improved silent alarm for the dialysis system. The silent alarm system, among other features, includes a transmitter that sends a signal to a remote alarming device, which can alert a caregiver to a dialysis system failure without disturbing the patent and/or people around the patent, who may be sleeping. 
         [0018]    A sixth aspect of the embodiments described herein includes a visual symbol or character shown on the display of the user interface of the dialysis system, which communicates pictorially ongoing happenings of the therapy, such as: (i) patient fill; (ii) solution dwell; (iii) patient drain; (iv) therapy status; (v) alarm status; (vi) patient history; (vii) therapy completed successfully; and (viii) system shut down. 
         [0019]    A first primary embodiment includes improved product configurations. Here, the cassette-based dialysis system can be configured to be placed on a patient&#39;s existing nightstand or be provided with its own nightstand. The instrument or actuator unit of the system can be configured to accept the disposable cassette horizontally or vertically. The display and user interface of the actuator unit may be integral to the actuator unit and for example be mounted at an upright angle or be rotatable and closeable with respect to the remainder of the actuator unit. 
         [0020]    It is also contemplated to arrange the disposable cassette, heater bag, supply bag and tubing in a variety of advantages configurations. In one implementation the disposable cassette is integrated to the heater bag. In another implementation, the heater bag is coupled to ports extending from the disposable cassette. The solution bags may be configured with any one or more of: (i) a spike seal that ensures a solution bag seal prior to pinching the solution bag; (ii) pre-attached tubing; and/or (iii) a delivery tray. The tubing may be configured with any one or more of: (i) the supply tubes tacked together; (ii) a larger diameter draw hose; (iii) the patient and/or drain line coiled; (iv) the patient and/or drain lines pre-attached to the cassette; (v) leur connections provided on the supply tubes for ready attachment to the supply bags; (vi) the patient tube pre-attached to the disposable cassette so as to be in proper orientation for operation with a primary sensor; (vii) clamps color-coded and/or configured with line identification. 
         [0021]    The drainage for the dialysis system may also be configured advantageously in a variety of ways. For example the drain tubes may be provided with adhesive bonding and/or a clamp to help secure the drain bag and/or the drain bag. The drain bag may be configured: (i) with a handle; (ii) to be reusable; (iii) to be a flexible bag or an at least semi-rigid container; (iv) to be a container with a handle oriented to easily tip the container and/or with wheels; and (v) to be pre-attached to the drain tube and/or the disposable cassette. 
         [0022]    The organization of the dialysis system is also configurable in a variety of ways advantageously. One implementation includes an organizational mat that prompts the patient to organize the fluid bags/containers properly and to gather the supplies needed. Another implementation provides a solution bag tray that orients the solution bags for optimum performance. Still a further implementation provides a nightstand, which holds any one or more of: (i) the actuator unit; (ii) additional supplies; (iii) solution/drain bag; (vi) disposable cassette; and (v) tubing. 
         [0023]    A second primary embodiment includes an improved display device, which employs a capacitance electromagnetic compliance (“EMC”) seal. The display device includes an insulating dielectric material (e.g., mylar film) placed between the metal case of the display device or monitor and a conductive coating located on the housing of the dialysis machine. The metal case and metal coating are electrically isolated from each other. The dielectric material and the two conductive surfaces form a capacitor that prevents leakage of electromagnetic energy. 
         [0024]    In one implementation a medical machine includes: an enclosure defining an opening, at least a portion of the enclosure being electrically conductive; an electrically operated component located inside the enclosure; a window placed adjacent to the opening; a conductive border abutting the conductive portion of the enclosure; an insulating border abutting the conductive border; and a video display including a case having an electrically conductive surface abutting the insulating border. 
         [0025]    In one implementation, the electrically operated component includes at least one apparatus selected from the group consisting of: a pump, a heater, a valve, a sensor, a pneumatic source, a disposable cassette, an activator, and an occluder. 
         [0026]    In one implementation, the window includes at least one characteristic selected from the group consisting of: (i) being at least substantially optically transparent; (ii) being electrically insulative; (iii) being at least substantially sealed to the enclosure; and (iv) being at least substantially impact resistant. 
         [0027]    In one implementation, the conductive border includes at least one characteristic selected for the group consisting of: (i) being a conductive film; (ii) being in contact with the conductive portion of the enclosure; (iii) being compressible; and (iv) being in contact with a ridge extending from the enclosure at least partially around the and overlapping the window. 
         [0028]    In one implementation, the enclosure includes at least one characteristic selected from the group consisting of: (i) the conductive portion thereof including an electrically conductive coating applied to the enclosure; (ii) being isolated electrically from the display; (iii) being sized to house components of a peritoneal dialysis machine; (iv) the opening thereof being shaped at least generally the same as the window; and (v) the conductive portion thereof contacting the conductive border to form a first capacitor plate, the conductive surface of the case forming a second capacitor plate, the insulating border forming a dielectric between the first and second capacitor plates. 
         [0029]    In one implementation, the insulative border includes at least one characteristic selected from the group consisting of: (i) being made of a dielectric material; (ii) being made of a plastic; (iii) being made of mylar, (iv) being sized at least substantially the same as the conductive border; (v) being shaped at least substantially the same as the conductive border; and (vi) being sandwiched between conductive portions of the enclosure and the display to form a capacitor configured to prevent leakage of electromagnetic energy from the enclosure. 
         [0030]    In one implementation, the video display includes at least one characteristic selected from the group consisting of: (i) being a color display; (ii) being a monochrome display; (iii) being operable with a touch screen; (iv) the at least partially conductive case forming a first capacitor plate, the conductive border and conductive portion of the enclosure forming a second capacitor plate; and (v) having a portion configured to be in positive engagement with a force providing member so that the display is pushed against the insulative border. 
         [0031]    In one implementation, the medical machine is a dialysis machine. 
         [0032]    In one implementation, a medical machine includes: an enclosure defining an opening, at least a portion of the enclosure being electrically conductive and acting as a first capacitor plate; a medical device component located inside the enclosure; a window placed adjacent to the opening; a video display with an at least partially conductive case acting as a second capacitor plate; and a dielectric member placed between the first and second capacitor plates, the plates and dielectric member forming a capacitor for preventing leakage of electromagnetic energy from the enclosure. 
         [0033]    In one implementation, the first and second capacitor plates contact the dielectric member. 
         [0034]    In one implementation, the dielectric member forms a border having an opening enabling information displayed by the video display to be seen through the window. 
         [0035]    In one implementation, the medical machine includes a conductive border contacting edges of the window and the conductive portion of the enclosure, the conductive border and the conductive portion of the enclosure acting as the first capacitor plate. 
         [0036]    In one implementation, the medical machine includes at least one characteristic selected from the group consisting of: (i) the medical device component including a fluid pump; (ii) the window being plastic; (iii) the conductive portion of the enclosure including a conductive metal coating applied to the enclosure; (iv) the conductive portion of the enclosure being a conductive ridge; (v) the dielectric member being made of plastic; and (vi) the display configured to display at least one of text and indicia relating to a therapy provided by the medical machine. 
         [0037]    In one implementation, the medical device component located inside the enclosure is capable of generating electromagnetic energy (“EMI”), and the capacitor is for preventing EMI from the medical device component from leaking through the enclosure and EMI from outside the medical device from leaking into the medical device. 
         [0038]    A third primary embodiment includes an improved elastomeric keypad. The keypad, among other features, includes an ambient light sensor that provides a signal output that the dialysis system uses to adjust the brightness and contrast of the display based on the amount of ambient light sensed. The ambient light sensor is imbedded into or is otherwise secured by the machine housing such that at least a portion of the sensor is oriented to be able to gather ambient light. The sensor is connected with electronics to a backlight control function. The output of the backlight control function controls the brightness of the user interface display and keyboard backlighting. In one implementation, an increase in ambient light results in a corresponding increase in backlight intensity. Conversely, a decrease in ambient light results in a corresponding decrease in backlight intensity. 
         [0039]    A fourth primary embodiment includes a low battery disconnect circuit for use with the peritoneal dialysis machine. The cassette-based system includes a battery back-up power source. When the system is obtaining power from the battery back-up, the output voltage of the battery back-up gradually declines over time. The battery output is connected to a voltage regulator circuit that regulates the battery output to a constant level. As the battery voltage declines, a point can be reached in which the regulator can no longer hold the output voltage constant. The disconnect circuit serves to optimize this point to increase the life of the battery back-up power source. 
         [0040]    The regulator circuit includes a metal oxide field effect transistor (“MOSFET”). In the circuit, the MOSFET acts as a variable resistor according to its inherent on-resistance versus gate voltage characteristic. The regulator controller compares a feedback voltage at the source of the MOSFET to an internal voltage reference and adjusts the voltage at the gate of the MOSFET to produce a desired, regulated output voltage. As the battery voltage declines, the regulator controller increases the voltage at the gate of the MOSFET, which according to the on-resistance versus gate voltage characteristic decreases the drain to source resistance, reducing the voltage drop across the MOSFET, so as to maintain the MOSFET source pin at a desired regulated voltage. As described in detail below, the MOSFET regulator controller and the remainder of the circuit enable the disconnection of the battery to be made at a voltage very close to the regulated voltage, maximizing battery back-up time. The circuit prolongs the use of the battery back-up and enables more cost effective components to be used. 
         [0041]    A fifth primary embodiment includes a silent or remote alarm apparatus that operates with the cassette-based peritoneal dialysis system. The system contains speakers that can be used to sound audible alarms at the machines. The system also includes a transmitter that can be used alternatively to send a signal to a remote alerting device. The display of the machine shows a visual message detailing the type of the alarm and/or instructions for addressing the alarm. A receiving unit receives a signal sent by the transmitter and generates an audio, visual and/or physical (e.g., vibrating) alarming output to the patient or to a caregiver or hospital member located remotely with respect to the patient. The signal for example can be sent to a bed shaker that wakes only the person that needs to be awakened, e.g., the patient or caregiver. Family members or other patients in the room with the patient do not have to be awakened needlessly. 
         [0042]    In an sixth primary embodiment, the user interface displays a figure or character that shows the progress of a number of treatment steps for the dialysis treatment. In the embodiments illustrated herein, the display of the user interface displays a cartoon, video or other changeable image of a drinking glass. The glass is filled during fill, dwell and drain cycles. The filling of the glass in essence tracks the time or percentage of completeness of the particular cycle. The glass includes indicia indicating whether the cycle is a fill, dwell or drain cycle. 
         [0043]    The glass is non-imposing and provides a friendlier way to instruct the patient during therapy. The glass is incorporated into other aspects of peritoneal dialysis, such as alarm conditions, status reports, patient history, therapy completed successfully and system shut down. 
         [0044]    It is therefore an advantage of the embodiments described herein is to provide improved configurations for the components of a cassette-based dialysis system. 
         [0045]    Another advantage of the embodiments described herein to provide improvements to the user interface of the dialysis system, such as an improved display, an improved keypad, an improved alarming capability and an improved state of therapy and therapy feature indication. 
         [0046]    Yet a further advantage of the embodiments described herein is to provide an improved battery back-up feature for a cassette-based dialysis system. 
         [0047]    Additional features and advantages of the embodiments described herein are described in, and will be apparent from, the following Detailed Description of the Disclosure and the figures. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0048]      FIGS. 1A to 1F  are perspective views illustrating different components of one configuration of a dialysis system employing the embodiments discussed herein. 
           [0049]      FIGS. 2A to 2F  are perspective views illustrating different components of another configuration of a dialysis system employing the embodiments discussed herein. 
           [0050]      FIGS. 3A to 3E  are perspective views illustrating different components of a further configuration of a dialysis system employing the embodiments discussed herein. 
           [0051]      FIG. 4  is a perspective view illustrating one example of a user interface for the dialysis system having a capacitance electromagnetic compliance (“EMC”) seal. 
           [0052]      FIGS. 5 to 7  are schematic and elevation views showing one example of a user interface for a dialysis system employing the embodiments discussed herein. 
           [0053]      FIGS. 8 and 9  are schematic views illustrating one example of a system employing the embodiments discussed herein having a low battery disconnect circuit. 
           [0054]      FIG. 10  is a schematic view illustrating one example of a dialysis system employing the embodiments discussed herein having a silent alarm capability. 
           [0055]      FIGS. 11A to 11D  are machine screenshots illustrating an embodiment of a graphical depiction of a fill cycle of a dialysis system employing the embodiments discussed herein. 
           [0056]      FIG. 12  is a machine screenshot illustrating an embodiment of a graphical depiction of a dwell cycle of a dialysis system employing the embodiments discussed herein. 
           [0057]      FIGS. 13A to 13D  are machine screenshots illustrating an embodiment of a graphical depiction of a drain cycle of a dialysis system employing the embodiments discussed herein. 
           [0058]      FIG. 14  is a machine screenshot illustrating an embodiment of a graphical depiction offering treatment information for a dialysis system employing the embodiments discussed herein. 
           [0059]      FIG. 15  is a machine screenshot illustrating an embodiment of a graphical depiction offering alarm information for a dialysis system employing the embodiments discussed herein. 
           [0060]      FIG. 16  is a machine screenshot illustrating an embodiment of a graphical depiction offering patient information for a dialysis system employing the embodiments discussed herein. 
           [0061]      FIG. 17  is a machine screenshot illustrating an embodiment of a graphical depiction allowing the patient to change graphics/color settings in a dialysis system employing the embodiments discussed herein. 
           [0062]      FIG. 18  is a machine screenshot illustrating an embodiment of a graphical depiction allowing the patient to change alarm settings in a dialysis system employing the embodiments discussed herein. 
           [0063]      FIG. 19  is a machine screenshot illustrating an embodiment of a graphical depiction allowing the patient to change alarm settings in a dialysis system employing the embodiments discussed herein. 
           [0064]      FIG. 20  is a machine screenshot illustrating an embodiment of a graphical depiction signifying that therapy has been successful for a dialysis system employing the embodiments discussed herein. 
           [0065]      FIG. 21  is a machine screenshot illustrating an embodiment of a graphical depiction signifying that the machine has gone into a standby mode for a dialysis system employing the embodiments discussed herein. 
       
    
    
     DETAILED DESCRIPTION 
       [0066]    The embodiments described herein relate to medical fluid delivery systems that employ a pump, such as a peristaltic pump. In particular, systems, methods and apparatuses for cassette-based dialysis therapies including but not limited to hemodialysis, hemofiltration, hemodiafiltration, any type of continuous renal replacement therapy (“CRRT”), congestive heart failure treatment, CAPD, APD (including tidal modalities) and CFPD are disclosed. The cassette is disposable and typically discarded after a single use or therapy, reducing risks associated with contamination. 
       Product Configurations 
       [0067]    Referring now to  FIGS. 1A to 1F  a first configuration for the components of system  10  is illustrated by configuration  350 . As discussed herein, in one embodiment the pumping technology used for system  10  is a peristaltic pump. It is expressly contemplated, however, that many features and embodiments discusses herein can be used with peristaltic pumps, volumetric pumps, pumps operated pneumatically, pumps operated mechanically, pumps operated hydraulically and any combination thereof. The component features discussed in connection configuration  350  and indeed in connection with configurations  370  and  390  shown in connection with  FIGS. 2A to 2F  and  3 A to  3 F, respectfully, are applicable to any of the different types of pumping technologies just previously described. Indeed, while cassette  50  is shown in connection with each of configuration  350 ,  370  and  390 . 
         [0068]    As seen in  FIG. 1A , configuration  350  of system  10  includes supply bags,  14 ,  16 , and  22  and drain bag  24 . Those bags are connected fluidly to machine or unit  60  via lines  28 ,  54 ,  20  and  32 , respectfully, as seen in  FIG. 1C  additionally.  FIG. 1A  further illustrates that configuration  350  of system  10  includes an organizational mat  352 , which is shown and discussed in more detail in connection with  FIG. 1F .  FIG. 1A  further illustrates that configuration  350  can be placed partly on a desk or nightstand, with drain bag  24  being placed on the floor. In the illustrated embodiment, supply bags  14 ,  16  and  22  and cassette  50  are loaded and maintained in an at least substantially horizontal configuration. 
         [0069]    Referring now to  FIG. 1B , machine or unit  60  is illustrated in more detail. Here, unit  60  is a single integrated device, which includes a horizontal front drawer  354 , the back of which curves vertically, so that a portion of cassette  50  is turned vertically for air separation purposes. Cassette  50  and heater bag  356 , shown in more detail in connection with  FIG. 1C , are loaded via drawer  354  simultaneously into unit  60 . Drawer  354  also aids in organizing cassette  50  and heater bag  356  to aid the patient in aligning, inserting and removing those items. To that end, the identification of the separate lines  28 ,  54 ,  20  and  32  is also shown on drawer  354 , so that the patient can match corresponding indicia on the lines with the markings on drawer  354  for proper cassette installation. In the illustrated embodiment, display  66  of machine or unit  60  is tilted at an angle of about forty-five degrees to about sixty degrees from vertical for ready viewing. Other angles could also be used. Unit  60  also includes controls  62  and  64 , which can be off-screen controls, such as membrane switches, or on-screen controls, such as a touch screen overlay. 
         [0070]    Referring now to  FIG. 1C , the disposable, sterile, fluid carrying portion of configuration  350  is illustrated. The disposable set includes cassette  50  and separate heater bag  356 , which are connected together via heater tubes. Thus, in configuration  350 , heater  38  is located inside machine  60 . As discussed above, unit  60  cooperates with drawer  354  to turn a portion of heater bag  356  upwards for air separation. In the illustrated embodiment, heater bag  356  is loaded first via drawer  354  into unit  60 . The distill or free end of heater bag  356  is turned upward. That end may contain a vent or a filter, such as a hydrophobic membrane, which enables air escaping from the fluid in the heating pathway to collect at the vertical upper end of heater bag  356  and to eventually be vented through such a vent or filter. 
         [0071]    The disposable set includes a tubing organizer  358 , which can be placed on the table or night stand to further assist the loading of cassette  50  and heater bag  356 . Organizer  358  holds supply lines  28 ,  54  and  20  next to one another. Those lines in an embodiment are tacked or otherwise held together, so that the patient knows that those lines are intended to be connected to supply bags  22 ,  16  and  14 , respectively. Drain line  32  in an embodiment has a larger diameter hose than do supply lines  28 ,  54  and  20 . This also helps the patient to keep the different lines straight in memory. Thus it should be appreciated that in configuration  350 , cassette  50  and the lines connected to organizer  358  are loaded through the front of the unit  60 , which places the tubes in an advantageous viewing area in front of the patient. 
         [0072]    The identification of supply lines  28 ,  54  and  20 , drain line  32  and patient line  12  is further aided via identifying markings. For example, clamps  360  ( FIG. 1C ) located at the distil ends of supply lines  20 ,  54 , and  28  and drain line  32  are color-coded. Furthermore, the clamps can have molded line identification or indicia. Patient line  12  is identified via a connector  362  at its distil end. Connector  362  is removably fixed to unit  60  as seen in  FIG. 1A  for priming. Unit  60  in one embodiment has a sensor, which senses whether connector  362  of patient line  12  is in proper position for priming before allowing therapy to begin. 
         [0073]    As seen in  FIG. 1D , supply bags  14 ,  16  and  22  each include a port  364  and a vent  366 . Vent  366  for example includes a filter or a membrane, such as a hydrophobic membrane, which enables gas to be purged from the supply bags. Ports  364  each include a seal, which is spiked via the ends of supply lines  28 ,  54  and  20 . The seal eliminates the need for a clamp on supply bag port  364 . 
         [0074]    Referring now to  FIG. 1E , an embodiment for drain bag  24  is illustrated. Drain bag  24  also includes a port  364  and vent  366  as described above in connection with  FIG. 1D . Bag  24  also includes a handle  368   a , which aids in carrying bag  24  when it is full of spent fluid. A handle  368   b  is also provided with machine  60  as seen in connection with  FIG. 1B  for its ready transport. As seen in  FIG. 1E , drain line  32  is provided with one or more apparatus, which enables the drain line to be fixed and held in a desired position. For example, drain line  32  can be provided with a flexible, adhesive-backed strip  372 , which may enables the drain line to be adhered to the desk or night stand, for example. Strip  372  in an embodiment slidably engages drain line  372  in frictional manner, so that strip  372  can be moved along drain line  32  to a desirable position. Additionally or alternatively, a clamp  374 , which can be reusable, is provided so that drain line  32  can be clamped in a desirable position. Clamp  374  slides over drain line  32  and in embodiment can be positioned frictionally along different areas of the drain line. 
         [0075]    As seen in  FIG. 1F , organizational mat  352  includes indicia  376   a  to  376   e , which identifies the component at the illustrated location and where a component, such as the supply bag and drain bag, should be located. Mat  352  is reusable and made of a washable material. The indicia can further include written instructions, reminders and other useful information, such as color codes for the clamps and lines. 
         [0076]    Referring now to  FIGS. 2A to 2F , a second configuration  370  for system  10  is illustrated. As before, configuration  370  is applicable to a dialysis system employing any of the different types of pumping technologies described herein.  FIG. 2A  shows configuration  370  using different shelves or levels of a desk, night stand, etc. Configuration  370  is advantageous in one respect because supply bags may be tucked out of the way, leaving unit or machine  60  as the primary component that the patient views. As seen additionally in  FIG. 2F , configuration  370  includes a bag stand  378 , which orients supply bags  14 ,  16 , and  22  in a position which allows gravity to help fluid travel from the supply bags to cassette  50 . Stand  378  also organizes supply bags  14 ,  16  and  22  and includes or defines a plurality of notches or openings that hold the tubing or connectors, which extend from the supply bags. Bag stand  378  in one embodiment is made of vacuum-formed plastic or metal or is otherwise made of any suitable material. 
         [0077]      FIGS. 2A and 2E  illustrate that configuration  370  includes or uses a reusable drain container  24 , which in the illustrated embodiment includes a rigid or semi-rigid housing  380 . Housing  380  defines or includes a handle  368   c . In the illustrated embodiment, housing  380  is attached to wheels  382  which further aid in the transporting of the housing.  FIG. 2E  also shows that handle  368   c  is positioned so that housing  382  maybe tipped easily for drainage. To that end, an opening  384  of container  24  positioned so as to be located at the bottom of housing  380  when it is tipped over. Housing  380  of reusable drain container  24  includes a reusable cap  386 , which when tightened on to mating threads of housing  380  compresses a ferral or other type of compressible apparatus or seal, located at the end of line  32 , into a mating connector located or defined by housing  380 . 
         [0078]      FIG. 2B  illustrates unit or machine  60  in more detail. As with unit  60  of configuration  350 , unit  60  of configuration  370  is a single integrated machine in the illustrated embodiment. Cassette  50  is loaded into unit  60  horizontally as illustrated. Supply and drain tubes again enter device  60  from the front for easy access. Video monitor  66  is hinged so that it maybe adjusted to a suitable angle relative to a table or nightstand on which it is placed, while closing to form a compact and portable unit. Rotatable monitor  66  operates in conjunction with controls  62  and  64 , which again can be off-screen input devices (e.g., membrane switches) or on-screen input devices that use a touch screen overlay. Unit  60  can also have a handle (not illustrated) or be provided with a bag or carrying case (not illustrated) for ready transport. 
         [0079]    Referring now to  FIG. 2C  cassette  50  is shown loaded into unit  60 . Cassette  50  includes an integrated fluid heating pathway  388 . Integrated fluid heating pathway  388  can be a spiral path, which communicates with pathways located within the valve portion of cassette  50 , such that to-and from-heater ports are not needed. Fluid heating pathway  388  operates with a heater  38  located within dialysis unit  60 . 
         [0080]    In the illustrated embodiment, patient line  12  and drain line  32  are preattached to ports of cassette  50 . Drain line  32  can again have a larger diameter than patient line  12  for reasons discussed above. Cassette  50  also has fluid connector or ports  392 , which connect to supply lines  20 ,  54 , and  28 . The supply lines or pigtails are preattached to supply bags,  14 ,  16  and  22 , respectfully. 
         [0081]    As seen additionally in  FIG. 2C , patient line connector  362  located at the end of patient line  12  is pre-clipped or fastened to cassette  50  to orient the patient connector in proper position for priming. Further, drain line  32  and patient line  12  are coiled, so that cassette  50  can be moved more easily. Clamps  360  located at the ends of drain line  32  and supply lines  28 ,  54  and  20  can be color-coded as discussed above in connection with configuration  350 . In an embodiment, connectors located at the ends of supply lines  28 ,  54  and  20  match with colors of luer connectors or ports  392  on cassette  50 . 
         [0082]    Referring now to  FIGS. 3A to 3E , a third product configuration  390  is illustrated for system  10 . Configuration  390  includes a dialysis machine or unit  60 , having input devices  62  and  64  and a display device  66 , including each of the alternative embodiments discussed above regarding those components. As seen in  FIGS. 3A and 3E , configuration  390  is provided with an APD night stand  394 . In  FIG. 3E , a bottom drawer opening  396   a  receives a tray  398   a . Tray  398   a  holds drain bag  24 . In the illustrated embodiment, drain bag or container  24  is placed in a tray  398   a , which is then slid into bottom opening  396   a . A middle tray  398   b  holds supply bags  14 ,  16  and  22  and cassette  50  in a middle opening  396   b . Tray  398   b  is shown in more detail in connection with  FIG. 3D . Top drawer  398   c  located in top opening  396   c  can be used for extra supplies for example. Drain container  24  can be pre-attached to cassette  50  or reusable as discussed above. 
         [0083]    As seen in  FIGS. 3C and 3D , the disposal portion of configuration  390  in one embodiment is integrated, so that the patient does not have to connect any solution bag lines  20 ,  28  and  54 . Also, patient line  12  and drain line  32  are pre-attached to cassette  50 . Here, patient setup merely requires the patient to place patient line connector  362  located at the end of patient line  12  on a hook or other attachment device  402  provided on the housing of unit  60  for prime. The patient connects drain line  32  to drain bag or container  24  and places container  24  in lower tray  398   a . As seen in  FIG. 3D , solution bags  14 ,  16  and  22 , which are preattached to cassette  50  are loaded together as packaged in tray  398   b . Here, the patient pulls cassette  50  from tray  398   b  and places it into a vertical slot  404  defined by machine  60 . Thus in configuration  390 , cassette  50  is monitored vertically, which can be advantageous from an air separation stand point. Tubing connected to cassette  50  enters unit  60  via the side of cassette  50  in the illustrated embodiment. Cassette  50  includes an integrated fluid heating pathway  386 , similar to or the same as that for configuration  370 . Drain line  32  can also have a larger diameter than the supply and patient lines. 
       Display with Electromagnetic Compliance (“EMC”) Seal 
       [0084]    Referring now to  FIG. 4 , one embodiment of a display usable with any of the machines or units  60  (e.g.,  FIGS. 1B ,  2 B and  3 B) described herein is illustrated by machine display  400 . Display  400  includes a video display device  406 . Video display device  406  is the component of machine display  400  that generates the various images, e.g., color or monochrome, seen by the patient. The metal case of video display device  406  makes intimate contact with an insulating dielectric film  408 , which in turn makes intimate contact with an electrically conductive foam  410 . One suitable display device  406  is provided for example, by Sharp Electronics, Color Thin Film Transistor (“TFT”) Liquid Crystal Display (“LCD”), model LQ057. Suitable materials for insulative dielectric film  408  include polyester, polycarbonate and mylar. The material can have a thickness of about 0.003 inch (0.075 mm). One suitable material for electrically conductive foam  410  is made by Schlegel or Insul-Fab, IFT-CF2-3030FR. 
         [0085]    In an embodiment, conductive foam  410  is pressed against conductive coated ridge  412 , which is built into or formed with the non-conductive machine casing  414 . Ridge  412  extends around the perimeter of opening  416  defined by machine casing  414 , positions window  418  within casing  414  and creates a surface for the conductive coating of ridge  412  to contact conductive foam  410 . Electrically conductive foam  410  has a larger outer dimension than does transparent window  418 , which in an embodiment is an optically transparent, impact resistant, plastic piece. Accordingly, the outer edges of conductive foam  410  extend beyond window  418  and thereby contact metal ridge  412 . Insulating dielectric  408  is the same size or wider in the inner and outer dimensions than is conductive foam  410 . Therefore, insulating dielectric  408  prevents conductive foam  410  from contacting the metal case of display device  406 . Insulating dielectric  408  thereby provides an electrically isolating barrier between conductive foam  410  and metal display  406 . 
         [0086]    Conductive foam  410  contacts ridge  412  of machine casing  414  establishing an electrical connection. In this configuration, the conductive surfaces  410 / 412 , the metal casing of display device  406  and the insulating dielectric material  408  sandwiched between those conductive surfaces form a capacitive electromagnetic compliance (“EMC”) seal. A pressure sensitive adhesive (“PSA”)  420  forms an environmental seal between transparent plastic window  418  and machine casing  414 . That is, PSA  420  prevents dust and dirt from entering the inside of machine display  400  via opening  416 . A mounting bracket (not shown) is fixed to machine casing  414 , for example, via threaded couplers  422  welded to, heat staked or otherwise formed with machine casing  414 . The bracket holds display device  406  and also compresses conductive foam  410  against display device  406  and ridge  412  of machine casing  414  to ensure good electrical contact between conductive foam  410  and the conductive coated ridge  412  of machine casing  414 . 
         [0087]    Machine display  400  takes advantage of the metal ridge  412  of casing  414 , which surrounds window  418 , and the metal casing of display device  406 . The resulting EMC seal prevents electromagnetic energy (“EMI”) generated by the electronics within machine casing  414  from exiting or passing through the casing  414  or display device  406 . The EMC seal also prevents EMI generated by outside electronic devices from entering the machine through the paths just described. The above-described apparatus eliminates the need for shielding the entire display opening with an electrically conductive window, which adds expense and can also adversely effect image quality. Machine display  400  eliminates the need for an electrically conductive window altogether and thus eliminates the disadvantages just described. 
       Display with Elastomeric Keypad 
       [0088]    Referring now to  FIG. 5 , one embodiment for a user interface operable with any of the machines  60  of system  10  (e.g.,  FIGS. 1A ,  2 A and  3 A) is illustrated schematically by user interface  430 . User interface  430  includes an ambient light sensor  432 , and interface circuit  434 , control electronics/control function  436 , a manual brightness button or other type of manual input  438 , a display backlight  440  and a keypad backlight  442 . Any one or more of the above-listed components can be provided on a printed circuit board (“PCB”) located within dialysis machine  60 . In an alternative embodiment, interface circuit  434  is provided with sensor  432 , located separately from the PCB. 
         [0089]    Ambient light sensor  432  senses an amount of ambient light in the room in which machine  60  is positioned and sends a signal such as a zero to ten volt or 4 to 20 milliamp variable output signal to the interface circuitry  434 . Interface circuit  434  conditions the signal from the ambient light sensor to make it readable or useful to the control electronics/control function  436 . 
         [0090]    The user interface backlight electronics  436  also receives a variable input signal from manual brightness input or rotary knob  438 . As described below in detail, input or knob  438  in one embodiment sets an initial brightness setting desired by the patient or operation. In an alternative embodiment, the signal from the manual brightness input  438  overrides the automatic backlighting provided via ambient sensor  432 , interface circuit  434  and backlight electronics  436 . As seen in  FIG. 6 , rotary knob operates with directional arrows  446 . 
         [0091]    Whether user interface backlight electronics  436  is controlled via sensor  432  and interface  434  or via a signal from manual controller  438 , the user interface backlight control function  436  outputs a variable amount of power to backlight display  440  and keypad backlight  442 . The power to display backlight  440  can be the same as the power to keypad backlight  442 , or the power to one of the backlights can be different, e.g., scaled by a factor, of the power to the other backlight. For example, the keypad backlight may be controlled automatically to be slightly less bright than the display backlight  440  set initially via input  438  or vice versa. In an alternative embodiment, display backlight  440  can be controlled independently from keypad backlight  442 . For example, although not illustrated, a second manual brightness control button, knob or controller can be provided, so that there is separate manual control of display backlight  440  and keypad backlight  442 . The user or patient may want to set the display backlight to be more brightly lit, while the keypad backlight is set to be more dim or vice versa. Separate controls would also allow the user to turn one of the backlights off, while keeping the other on if desired. 
         [0092]    It is expected that machine  60  (e.g.,  FIGS. 1B ,  2 B and  3 B) will be operated in a varying ambient light environment because the machine may be used to perform dialysis at home and at any time during the day or night. For example, the machine may be set up at night under normal room light conditions and perform therapy thereafter while a person sleeps with the lights off. Machine  60  at any time during therapy may need to warn the patient of an error or alarm and wake the patient potentially in a dark or dimly lit room. User interface  430  including automatically variable lighting automatically adjusts backlight intensity to compensate for changes in ambient light level so that such errors or alarms may be seen easily. 
         [0093]      FIG. 6  shows machine  60  operating with variable ambient light user interface  430 . Ambient light sensor  432  is positioned to receive light impinging on machine  60 . Light sensor  432  in an embodiment includes a photo receptor having a spectral response approximately that of the human eye, such as an LX1970 Visible Light Sensor provided by Microsemi Corporation, Garden Grove, Calif. This sensor includes processing that provides a photopic light wavelength response curve that nearly duplicates that of the human eye. Control function  436  shown in  FIG. 5  sets the backlight brightness  440  and  442  to the level set by the user and modifies the backlight in response to changing ambient light levels. For example, control function  436  can be configured so that an increase in ambient results in a corresponding increase in backlight intensity  440  and  442 . Conversely, a decrease in ambient light results in a corresponding decrease in backlight intensity  440  and  442 . Backlight control function  436  also compensates for any non-linearity of ambient light sensing. Backlight control function/electronics  436  can be a dedicated analog circuit, a dedicated digital circuit (such as a microcontroller), hybrid of both or be a functional element of a shared-embedded application processor. The function may also be implemented on an application specific integrated circuit (“ASIC”). 
         [0094]    As discussed above, the patient adjusts the ambient light setting via adjustment device  438 , which includes a dial or knob for example. Device  438  controls a variable electrical output signal to backlight control function  436 . Function  436  can be set to time-out after a period of non-adjustment, following a period of adjustment or control  436  to know when the desired setting has been made. Thus after the patient changes the desired amount of light, circuitry  434  waits a period of time after the change to know that the change has been set. After this amount of time, control function/electronics  436  is set to assume that the desired backlight setting has been made. 
         [0095]    The setting can be made in any ambient condition. Control function/electronics  436  is configured to modify its output if the ambient conditions change, so that the overall backlight brightness level stays at the level set by the user. For example, if the patient sets a desired level during normal lighting conditions to a high backlit level and then night falls or the patient turns out room lights, electronics  436  would decrease the power to backlights  440  and  442  and maintain the relative brightness between the backlights  440  and  442  and the ambient light. In this embodiment, a fixed level is adjustable after which circuitry  434  adjusts the backlight  440  and  442  to achieve or maintain that setting made by the patient. In another embodiment, manual control or rotary knob  438  overrides an automatic, e.g., optimized setting made in software in which power is adjusted based on ambient light compared to the automatic setting. 
         [0096]    In an alternative embodiment, control function  436  is configured to compensate for the human eye&#39;s change in sensitivity due to ambient light levels integrated over time. As is known, the longer a person resides in the dark, the more sensitive the person&#39;s eye becomes. This phenomenon is sometimes termed as “dark adaptation” or “unaided night vision.” In this alternative embodiment, control function  436  would gradually reduce power to one or both of display backlight  440  and keypad backlight  442  over time and over a steady ambient light reading via sensor  432 . This feature in an embodiment is performed only when control function  436  determines that it is dark enough to do so, such as at a particular ambient light, read from sensor  442 , or lower. 
         [0097]    In  FIG. 6 , user interface  430  includes buttons that are visible to the user, such as buttons  62   a  to  62   d . User interface  430  also includes “hidden” buttons or inputs  64   a  and  64   b . In an embodiment, visible buttons  62   a  to  62   d  are three dimensional and raised to allow the patient to have enhanced finger traction and feel and for ease in locating a desired function. Buttons  62   a  to  62   d  provide tactile feedback when pressed. Each visible button  62   a  to  62   d  includes a three dimensional icon or indicia, which can be raised or inset so that a visually impaired person can identify a particular button through touch alone. Visible buttons  62   a  to  62   d  in an embodiment are color-coded or otherwise unique visually and/or tactily to further aid in their identification. As seen in  FIG. 7 , each visible button  62   a  to  62   d  is backlit individually, wherein control function  436  of  FIG. 5  can be configured to light only buttons which are currently operational. 
         [0098]    Hidden buttons  64   a  and  64   b  are provided behind front panel  428 . Inputs  64   a  and  64   b  are accordingly shown in phantom. Front panel  428 , however, may include indicia  444  that mark the areas of hidden buttons  64   a  and  64   b . The patient presses icons  444  displayed on front panel  428  to activate hidden buttons  64   a  and  64   b . Hidden buttons  64   a  and  64   b  can also provide tactile feedback through front panel  428  to inform the patient that the hidden button is being activated. Further, the patient can view changes occurring on video monitor  66  to receive such feedback and recognition. Hidden buttons  64   a  and  64   b  are advantageous for certain applications, including but not limited to nurse mode or service mode buttons or other buttons that are not used typically by the patient but used instead by clinicians or service personnel. 
         [0099]    Although four visible buttons  62  and two hidden buttons  64  are illustrated, user interface  430  can have any suitable number of visible and hidden buttons, which can be push type buttons, rotary knobs, such as rotary knob  438 , toggle switches, maintained or momentary buttons, sliding input devices, and any suitable combination thereof. 
         [0100]    As discussed throughout this application, electromechanical buttons  62  (referring collectively to button  62   a  to  62   d ) and hidden buttons  64  (referring collectively to buttons  64   a  and  64   b ) can instead be provided on a touch screen overlay, which operates with video screen  66 . It is advantageous to use the electromechanical configuration in one respect because the electromechanical buttons allow for the buttons to be three-dimensional, which enhances tactile feedback and recognition. 
         [0101]    Referring now to  FIG. 7 , a light emitting diode (“LED”) board  426  is illustrated. LED board  426  shows different patterns for keypad backlighting  442  ( 442   a  to  442   f ) discussed above in connection with  FIG. 5 . In particular, LED board  426  includes backlight pattern  442   a  operable with visible button  62   a  ( FIG. 6 ), backlight pattern  442   b  operable with visible button  62   b  ( FIG. 6 ), backlight pattern  442   c  operable with visible button  62   c  ( FIG. 6 ), backlight pattern  442   d  operable with rotary knob  438  ( FIG. 6 ), backlight pattern  442   e  operable with directional arrows  446  ( FIG. 6 ), and keyboard backlight pattern  442   f  operable with visible button  62   d  ( FIG. 6 ). Patterns  442   a  to  442   f  are arranged as desired to provide a desired amount and spacing of backlighting behind buttons  62  ( 62   a  to  62   d ) and control knob  438 . As discussed previously, LED arrangements  442   a  to  442   f  can be lit individually, so that only active buttons are lit for example. This can help in machine setup and operation to guide the patient through different screens of therapy. 
       Low Battery Disconnect Circuit 
       [0102]    Referring now to  FIGS. 8 and 9 , circuit  470  illustrates one embodiment of a low battery disconnect circuit used with the electronics and user interface of system  10 . Circuit  470  is located within control unit  60  (e.g.,  FIGS. 1B ,  2 B and  3 B) and in an embodiment is provided on a printed circuit board, such as a delegate circuit board, which communicates with a supervisory PCB. Circuit  470  provides back-up power to machine  60  in an event that the main power source is interrupted. When the back-up power is used its output voltage level gradually declines over time as is known. The electronics driven by the battery back-up however need a steady voltage to operate reliably. A voltage regulator can be used to regulate the voltage at a steady level. As battery voltage declines, the regulator reaches a point that it cannot hold the voltage output steady based on the voltage it sees from the battery. If the duration of the main power source interruption continues long enough, the battery discharge continues to the point that loss of regulation occurs. When this happens the machine must be shutdown. This result should be avoided to ensure reliable machine operation. Circuit  470  enables the disconnect point to be safely near the point of loss of voltage regulation. Accordingly, circuit  470  lengthens the amount of time that machine  60  can run on battery back-up. 
         [0103]    Circuit  470  includes a battery  472 , a metal oxide semiconductor field effect transistor (“MOSFET”)  474 , a voltage regulator  476 , a voltage comparator  478 , which receives a reference voltage  480 , a regulated voltage output  482  and system ground  484 . A negative terminal of battery  472 , the voltage regulator  476  and the regulated voltage output  482  are all referenced to system ground  484 . 
         [0104]    Voltage regulator  476  receives a disable input  486   a  from voltage comparator  478  and a feedback input  486   b  from the source  488  of MOSFET  474 . Regulator  476  also provides a voltage output  494  to the gate  490  of MOSFET  474  as well as to a positive terminal of voltage comparator  478 . One suitable voltage regulator  476  is provided by Micrel Semiconductor Inc, San Jose, Calif., part # MIC 5158, which is used in combination with a latch (not illustrated) that latches the disabled state. The positive terminal of battery  472  is connected electrically to the drain  492  of MOSFET  474 . 
         [0105]    Circuit  470  takes advantage of an inherent characteristic MOSFET  474 , which is an on-resistance versus gate voltage characteristic.  FIG. 9  illustrates this characteristic. The characteristic is as follows. As discussed, the voltage of battery  472  needs to be higher than the regulated output  494  of voltage regulator  476  to provide a linear regulator typology. For example, the starting voltage of battery  472  can be six VDC, while the regulated output  494  is five VDC. The initial fully charged battery  472  can actually have a voltage of 6.1 VDC, for example. A voltage reference  480  supplied to the negative terminal of voltage comparator  478  in this example could be five VDC. Regulator  494  compares feedback voltage  486   b  to the voltage reference and adjusts its output  494  to gate  490  of MOSFET  474  so that the regulated output  482  is five VDC. 
         [0106]    When drain  492  of MOSFET  474  for example sees an initial voltage 6.1 VDC from battery  472  and source  488  is set to five VDC, a voltage drop (“VDS”) of 1.5 VDC occurs across MOSFET  474 . As voltage of battery  472  declines, regulator  476  increases its output  494  at gate  490  of MOSFET  474 , which decreases the drain to source on-resistance as seen in  FIG. 10 , and which therefore reduces the voltage drop across MOSFET  474  to maintain the voltage at MOSFET source  488  to be 5 VDC. 
         [0107]    In circuit  470 , MOSFET  474  therefore acts like a variable resistor. If for example the load being driven by regulated output  482  is drawing 1 Amp and batter  472  has already been drained to the point at which its voltage is 5.1 VDC, the drain-to-source voltage (“VGS”) is 0.1 VDC and the drain-to-source resistance is 0.1 Ohms (0.1 VDC÷1 Amp=0.1 Ohm). When RDS is at 0.1 Ohm as seen in  FIG. 10 , VGS is about three VDC. As battery voltage continues to decline, the operating point of MOSFET  474  moves down along the curve of  FIG. 9 . Here, regulator  476  continues to increase VGS, while the resistance of MOSFET  474  continues to decrease in compensation. 
         [0108]    As seen in  FIG. 9 , when RDS drops to about 0.03 Ohm, the curve begins to flatten considerably, so that VGS has to increase more and more dramatically to effect the same change in RDS. When VGS reaches 12 VDC, the curve is almost completely horizontal, meaning MOSFET  474  is almost fully on and RDS is about 0.022 Ohm. Here the threshold of comparator  478  is finally reached or surpassed when VGS becomes more positive than the threshold voltage. When VGS reaches this 12 VDC threshold in the example, comparator  478  switches and regulator  494  becomes disabled, driving VGS to zero, disconnecting battery  472  from the load connected to regulated output  482  effectively. 
         [0109]    In one embodiment, the minimum achievable RDS for MOSFET  474  is about 0.02 Ohm. Regulator  476  is chosen such that it can drive VGS to at least 15 VDC, so that RDS can reach 0.02 Ohm according to  FIG. 10 . If it is assumed again that the load driven by regulated output voltage  482  is one Amp, then for example VDS is 0.02 VDC at the minimum RDS of MOSFET  474  of 0.02 Ohm. In the example, the lowest voltage that battery  472  could provide to yield a regulated output voltage at  482  would therefore be 5.02 VDC. Reference voltage  480  for comparator  478  is set in one embodiment to 12 VDC. As discussed above, this yields an on-resistance of 0.022 Ohms, which in the one Amp example occurs when battery voltage drops to 5.022 VDC. Thus, the theoretical minimum for battery  472  is 5.02 VDC, while the actual sustainable voltage minimum for battery  472  is 5.022 VDC. This results in a mere loss of 2 millivolts above the theoretical limit. 
         [0110]    Circuit  470  accordingly provides topology that allows for lower tolerances and therefore lower precision and thus lower cost parts to be used in a safe and reliable circuit. It should be appreciated that even if the actual to theoretical low voltage output varies by plus or minus 25%, the resulting disconnect threshold varies by less than 5 millivolts. It should also be appreciated therefore that circuit  470  eliminates the need for a precision comparator function and safety margin, which has been used in the past to ensure that the threshold does not drop below the level at which regulation can be maintained. Adding a safety margin means that the nominal threshold voltage is moved higher, which results in a disconnected or battery voltage higher than that achievable with a topology of circuit  470 . Disconnecting at a higher voltage means less time available to operate on battery back-up. 
         [0111]    In an alternative embodiment, the output of comparator  478  is used to trigger an interrupt to one or more processors of system  10 , trigger a delay circuit (not illustrated) and have the output of the delay circuit trigger the shutdown of system  10 . This approach signals to the one or more processor that power is to be disconnected shortly, giving the processor an opportunity to prepare for shutdown of system  10 . For example, the system could send an alarm to the patient, close one or more valve, ramp down one or more pump and record the status of therapy (such as the amount of fluid pumped per current cycle, amount of ultrafiltrate removed, etc.) and perform any other safety measure needed to prepare for shutdown. 
         [0112]    It is also contemplated to use circuit  470  or the alternative interrupt circuit to notify a processor whenever a switch to battery back-up occurs, wherein the processor has the further capability to shut off power. In such case, circuit  470  or the alternative interrupt circuit can provide a back-up shut-off circuit in case the processor fails to shut itself off. 
         [0113]    In a further alternative embodiment, a second comparator is provided having a voltage threshold less than that of comparator  478 . The lower threshold voltage second comparator generates a processor interrupt signal when VGS becomes more positive than the threshold voltage. The higher threshold voltage of comparator  478  causes the system to be shut down when VGS becomes more positive than the higher threshold voltage. This causes a time delay. 
       Silent Alarm Capability/Remote Alerting 
       [0114]    Referring now to  FIG. 10 , one embodiment of system  10  having a silent alarm capability is illustrated. As discussed above, it is desirable in certain circumstances not to have machine or unit  60  of system  10  (e.g.,  FIGS. 1A ,  2 A and  3 A) sound an alarm itself. For example, unit  60  may have to be located near other sleeping people who do not need to be awoken upon an alarm condition. In other instances, the patient and/or patient&#39;s spouse can be hearing impaired or deaf and not be able to respond to an audible alarm from unit  60  of system  10 . As discussed below, the silent alarm capability of system  10  solves these dilemmas. 
         [0115]      FIG. 10  shows the machine  60 , which is configured similar to that shown in connection with  FIG. 3B . It should be appreciated, however, that the silent alarm capability can be provided with any of the machines  60  described herein for system  10 . Machine  60  houses a transmitter  500 . One suitable transmitter  500  is provided by Harris Corporation SC-DOT1003-1 transmitter. Another suitable transmitter is an Alert Master Model 6000, part number AMER-AM 6000. In an embodiment, transmitter  500  is microprocessor controlled. The microprocessor in an embodiment is provided on a safety controller or safety PCB, which operates with a supervisory microprocessor. The integration of transmitter  500  and microprocessor control helps to prevent false alarms because the microprocessor decides when transmitter  500  should send signal  502 . 
         [0116]    Transmitter  500  transmits a radio frequency (“RF”), microwave, ultrasonic or infrared signal  502 , which can be received by one or more remote receiver. For example, the remote receiver can be a remote alarm, headset or computer  504 , which generates a visual or audible alarm in a place located remotely from machine  60 . Alarm  504  alerts a caregiver or relative that machine  60  of system  10  is experiencing an alarm condition. Video monitor  66  of machine  60  posts an alarm message  506 , which can (i) describe the nature of the alarm and/or (ii) provide a suggested course of corrected action. Signal  502  can be continuous, e.g., for three seconds, or pulsed as desired. 
         [0117]    In an alternative embodiment, transmitter  500 , as provided by Harris Corporation CC-PS1001, Private Page, is a local wireless paging system that sends its signal  502  to a remote pager or cellphone  508 . Pager or cellphone  508  is worn by a caregiver or relative. The pager responds to signal  502  in a known manner, alerting the caregiver or relative to proceed to machine  60  and observe visual message  506 . 
         [0118]    In still a further alternative embodiment, transmitter  500  sends signal  502  to a bed shaker  510 . One suitable bed shaker is provided by Harris Communications Super-Shaker Model SA-SS120V, 120VAC. DC Model is SA-SS12V. Bed shaker  510  is placed beneath the patient or is otherwise coupled to the patient&#39;s bed, so that the patient is awakened upon an alarm. This can be done so as not to wake other people nearby. 
         [0119]    In further alternative embodiments, signal  502  can be sent to any combination of remote alarm  504 , pager  508  and/or bed shaker  510 . Further, machine  60  can be configured with one or more speakers  512 . Speakers  512  provide an audible alarm at machine  60 , which can be made in lieu of or in addition to the signaling of the remote devices. Speakers  512  can alternatively provide an audible version of message  506 , which audibly tells the patient, caregiver or relative what to do to correct the current alarm condition. For example, signal  502  can be sent to remote alarm  504  or pager  508 , alerting a person to come to machine  60 , at which point the person hears an audible message from speaker  512  informing the person of the nature of the alarm and likely corrective action. 
         [0120]    In any of the previously mentioned embodiments involving transmitter  500 , the transmitter  500  exist alternatively externally to machine  60  and its display  66 . This is done via an external interface connection through machine  60 . The interface of machine  60  provides a polar/binary signal, ON/OFF signal or data stream interface, such as serial or parallel interface, depending upon the type of remote transmitter  500  used. 
       Graphical Display of Progress Dialysis Treatment Steps 
       [0121]    Referring now to  FIGS. 11A to 11G , screen shots of video monitor  66  of dialysis machine  60  of system  10  (e.g.,  FIGS. 1A ,  2 A and  3 A) illustrate a fill cycle, such as a PD fill cycle graphically via a character  520 . As shown here and in subsequent figures, character  520  is used throughout the therapy, to provide the patient with a consistent and familiar treatment display. 
         [0122]    In the illustrated embodiment, a character  520  is shown as an animated drinking glass. It should be appreciated, however, that character  520  can have other suitable forms, shapes and/or indicia. In one embodiment, different characters or shape of a same character are provided as choices to the patient in a set-up mode. The character or shape chosen is used thereafter throughout the screens to display therapy progress and other information discussed below. The patient can change the character or shape at any time or in between treatments. 
         [0123]    In a preferred embodiment, character  520  has a friendly appearance, which also aids in relieving the stress of treatment. Character  520  adds a human element to therapy and provides useful information to the patient. It is contemplated that when such information is presented in a user-friendly format, the patient has a better probability of receiving and understanding the information. 
         [0124]    In the fill cycle of  FIGS. 11A to 11D , glass  520  is shown initially empty in  FIG. 11A  and is filled incrementally in  FIGS. 11B and 11C , before being filled completely in  FIG. 11D , indicating that the fill cycle is complete. Character  520  includes or has a therapy indicator  522 , which in the illustrated embodiment is a hand extending from the body of glass  520 , which points to or otherwise indicates which cycle of the therapy is currently underway. An up arrow  524   a  is provided initially to illustrate that the level of dialysis fluid is increasing, i.e., that a fill cycle is occurring. The water level in glass  520  on the other hand indicates a stage of a particular cycle. A fuller glass indicates that a later portion of the current cycle is taking place. The indicia of character  520 , e.g., the face shown on the glass, is also consistent with the fact that system  10  is currently in an active, e.g., fill mode. 
         [0125]    Referring now to  FIG. 12 , a screen shot of video monitor  66  illustrates a dwell cycle, which occurs after the patient&#39;s peritoneum has been filled with a fill volume of dialysate. The dwell cycle is a relatively inactive cycle for system  10 . Machine  60  is not pumping liquid to or from the patient. Thus, indicia  526  illustrates that the glass appears to be resting or sleeping. Up arrows  524   a  ( FIGS. 11A to 11D ) are replaced by circular or dwell arrow  524   b . Dwell arrow  524   b  indicates that the volume of fluid within the patient&#39;s peritoneum is currently not changing but is instead circulating or moving within the patient to remove waste and toxins. Glass  520  remains full of fluid during this period because the patient&#39;s peritoneum also remains full of fluid. 
         [0126]    Referring now to  FIGS. 13A to 13D , character  520  animates a drain cycle. Animations for any of the cycles can be cartoon animations, video clips and any combination thereof. Here, glass  520  is drained progressively in  FIGS. 13A to 13D  to indicate that drain is taking place and how much of the drain cycle has occurred. Glass  520  is full at the beginning of the drain cycle in  FIG. 13A . At the end of the drain cycle in  FIG. 13D , glass  520  is emptied completely, indicating the end of the drain cycle. Character indicator  522  and down arrow  524   c  both point downward, indicating fluid is leaving the patient, that is, indicating that machine  60  is currently in a drain cycle. 
         [0127]    Any of the fill, dwell and drain cycle sequences can be accompanied by an elapsed time display, a time remaining display, an indication of whether the cycle, e.g., drain cycle is a first drain cycle, a second drain cycle, for example. The face of glass  520  also indicates that the glass is awake, e.g., that machine  60  of system  10  is in an active pumping cycle. 
         [0128]    In an embodiment, the filling of glass  520  in any cycle occurs continuously, that is, the fill level is moving continuously albeit slowly during a particular cycle. In another embodiment, the level changes after an increment of time, e.g., every ten seconds, every thirty seconds, every minute, every five minutes, etc. Or, the level changes after an increment of volume, e.g., after every 10 millimeters pumped, 30 millimeters pumped, etc. The filling of glass  520  is also tied to other events that occur during treatment that may stop the filling. For example, if an alarm condition occurs in which pumping is stopped, video monitor  66  is configured to stop the display of the filling of glass  520 . 
         [0129]    Referring now to  FIGS. 14 to 16 , video monitor  66  is further configured to display other aspects of therapy, such as PD. As seen in  FIGS. 14 and 16 , character  520  is used in certain of these additional displays, while  FIG. 15  illustrates that character  520  does not have to be displayed in each screen shot or for each feature of system  10 . 
         [0130]      FIG. 14  illustrates a therapy report or therapy tracking screen in which character  520  holds a report  528  indicating that particular parameters of a previous treatment or therapy have been recorded. In an embodiment, video monitor  66  operates with a touch screen overlay, in which case the patient can press therapy report  528  to review treatment information. Treatment information can include any potentially desirable information, such as, treatment time, volume delivered, fill times, dwell times, drain times, number of cycles, UF removed, average dialysate temperature, alarm information, etc. In an alternative embodiment, electromechanical inputs, such as visible buttons  62  or hidden button  64  are used to recall information indicated by therapy report  528 . 
         [0131]      FIG. 15  illustrates an alarm screen, which includes an alarm indicator  530  and an alarm report  532 . In an embodiment, the screen of  FIG. 15  is displayed upon an alarm condition. If video monitor  66  operates with a touch screen overlay, either one or both of alarm indicator  530  and alarm report  532  can be touched to cause visual, audio or audiovisual alarm information to be given to the patient. In an alternative embodiment, the screen of  FIG. 15  is shown at the end of treatment so that the patient can review a separate alarm report  532  to learn of any alarm conditions that occurred during the previous therapy or to learn of any alarms that have occurred over recent therapies, such as over the last week or month. 
         [0132]    In  FIG. 16 , video monitor  66  shows a patient information screen. Here, character  520  is shown in combination with a file or folder  534 , which represents a patient file or patient history. Here again, if video monitor operates with a touch screen overlay, file  534  can itself be selected to show patient history, treatment parameters, background information and any other desirable patient-specific information. Otherwise, electromechanical inputs are used. 
         [0133]    In an embodiment, the screens of  FIGS. 14 to 16  are sub-screens obtained selectively via a main screen or supervisory sub-screen. Sub-screen selection can be done via a touch screen input or via electromechanical input, such as a scrolling input device that enables the patient to scroll through the icons representing the different screens (e.g., characters  520  in different settings) before selecting one of the icons to display the selected screen. 
         [0134]    Referring now to  FIGS. 17 to 19 , different screen shots of video monitor  66  show different icons in combination with an up and down arrow  536 . Up/down arrow  536  indicates that corresponding settings can be changed for a particular function indicated by its associated icon  520 ,  530  or  538 .  FIG. 17  for example shows glass  520 , which if pressed allows the user to change characters, e.g., from a glass to a person, color of the character, e.g., blue to red, or shape of the character, e.g., glass as shown to a mug, for example. To these ends, any of the screens discussed herein can be associated with a touch screen overlay, which communicates with a touch screen controller, which in turn communicates directly or indirectly with a supervisory processor, controller or printed circuit board. Thus, glass  520  and arrow  536  can correspond to selectable areas or the touch screen. Alternatively, membrane switches or other types of electromechanical input devices are provided to enable the user to interact with glass  520  and arrow  536 . 
         [0135]      FIG. 18  shows arrow  536  operable with alarm  530 . This screen enables the patient to change (as indicated by up and down arrow  536 ) the alarm settings. Alarm  530  can be colored yellow or red or otherwise brightly to indicate that the function is significant or to caution or warn the patient of a particular condition.  FIG. 19  shows arrow  536  operable with a control panel  538 . This screen allows the operator to change instrument settings, such as, volume settings, brightness settings and other user preferences relating to the operation of the dialysis machine. 
         [0136]    Referring now to  FIGS. 20 and 21 , video monitor  66  illustrates character  520  at the end of therapy or cycle.  FIG. 20  illustrates a therapy successfully completed screen. Here character  520  and character indicator  522  indicate that the previous treatment or treatment cycle has been completed successfully.  FIG. 21  shows character  520  in a rest or sleep mode. Here, character  520  is indicating that the machine, while powered, is in a shut-down or dormant mode, in which therapy has ended or is in a paused or waiting state for a task to be completed or command to be entered. 
         [0137]    Character  520  is shown above displaying parameters for a PD system. In an alternative embodiment, character  520  is used in a blood filtering dialysis therapy, such as, HD, HF or HDF. Here, character  520  can indicate ultrafiltration and the percentage of a prescribed amount of ultrafiltrate that has been removed at a certain point during treatment. 
         [0138]    It should be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the present disclosure and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the appended claims.