Abstract:
A stand for a medical fluid treatment, a system for supporting medical fluid bags, and a method for testing and sensing whether a bag or a seal in a chamber of a multi-chamber bag has been broken prior to providing therapy. A stand stores one or more medical fluid bags, each bag stored on a single shelf. Each shelf has a sensor for sensing the presence or absence of fluid in the bag, and reporting the status of the bag to a central location, such as a computer. The sensor can also detect and report on whether fluid has leaked from the bag, or in the case of bags with two or more chambers, if a leak in a frangible seal separating the chambers has developed.

Description:
BACKGROUND 
       [0001]    The present invention generally relates to dialysis systems. More specifically, the present invention relates to an apparatus and method for sensing whether a chamber in a multi-chamber dialysate bag leaks or has been broken. 
         [0002]    Due to disease, injury or other causes, a person&#39;s renal system can fail. In renal failure of any cause, there are several physiological derangements. The balance of water, minerals and the excretion of daily metabolic load is no longer possible in renal failure. During renal failure, toxic end products of nitrogen metabolism (urea, creatinine, uric acid, and others) can accumulate in blood and tissues. 
         [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 sustaining. One who has failed kidneys could not continue to live without replacing at least the filtration functions of the kidneys. 
         [0004]    Hemodialysis and peritoneal dialysis are two types of dialysis therapies commonly used 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 to connect the blood flow to and from the hemodialysis machine. As blood passes through a dialyzer in the hemodialysis machine, the dialyzer removes the waste, toxins and excess water from the patient&#39;s blood and returns the blood back to the patient. A large amount of dialysate, for example about 120 liters, is used to dialyze the blood during a single hemodialysis therapy. The spent dialysate is then discarded. Hemodialysis treatment lasts several hours and is generally performed in a treatment center about three or four times per week. 
         [0005]    Peritoneal dialysis utilizes a dialysis solution or “dialysate”, which is infused into a patient&#39;s peritoneal cavity through a catheter implanted in the cavity. The dialysate contacts the patient&#39;s peritoneal membrane in the peritoneal cavity. Waste, toxins and excess water pass from the patient&#39;s bloodstream through the peritoneal membrane and into the dialysate. The transfer of waste, toxins, and water from the bloodstream into the dialysate occurs due to diffusion and osmosis, i.e., an osmotic gradient occurs across the membrane. The spent dialysate drains from the patient&#39;s peritoneal cavity and removes the 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 and continuous flow peritoneal dialysis. CAPD is a manual dialysis treatment, in which the patient connects an implanted catheter to a drain and allows a spent dialysate fluid to drain from the peritoneal cavity. The patient then connects the catheter to a bag of fresh dialysate and manually infuses fresh dialysate through the catheter and into the patient&#39;s peritoneal cavity. The patient disconnects the catheter from the fresh dialysate bag and allows the dialysate to dwell within the cavity to transfer waste, toxins and excess water from the patient&#39;s bloodstream to the dialysate solution. After a dwell period, the patient repeats the manual dialysis procedure. 
         [0007]    In CAPD the patient performs several drain, fill, and dwell cycles during the day, for example, about four times per day. Each treatment cycle typically takes about an hour. Manual peritoneal dialysis performed by the patient requires a significant amount of time and effort from the patient. 
         [0008]    Automated peritoneal dialysis (“APD”) is similar to CAPD in that the dialysis treatment includes a drain, fill, and dwell cycle. APD machines, however, automatically perform three to four cycles of peritoneal dialysis treatment, typically overnight while the patient sleeps. The APD machines are fluidly connected to a catheter implanted in the patient. The APD machines are also fluidly connected to a source or bag of fresh dialysate and to a fluid drain. 
         [0009]    The APD machines pump fresh dialysate from the dialysate source, through the catheter, into the patient&#39;s peritoneal cavity and allow the dialysate to dwell within the cavity so that the transfer of waste, toxins and excess water from the patient&#39;s bloodstream to the dialysate solution can take place. The APD machines then pump spent dialysate from the peritoneal cavity, though the catheter, to the drain. APD machines are typically computer controlled so that the dialysis treatment occurs automatically when the patient is connected to the dialysis machine, for example, when the patient sleeps. That is, the APD systems automatically and sequentially pump fluid into the peritoneal cavity, allow for a dwell, pump fluid out of the peritoneal cavity and repeat the procedure. 
         [0010]    As with the manual process, several drain, fill, and dwell cycles will occur during APD. A “last fill” is typically used at the end of APD, which remains in the peritoneal cavity of the patient when the patient disconnects from the dialysis machine for the day. APD frees the patient from having to manually performing the drain, dwell, and fill steps. 
         [0011]    For each of the above-described dialysis therapies, each of the associated cycles typically consumes a separate bag of solution or dialysate. Over the course of therapy, multiple bags of such solution are used. In many instances, solution bags with a single chamber or pouch are used. In such a case, the solution is completely premixed, sterilized and ready to use. In other instances, the bags include multiple chambers that divide a base solution from an additive. With multi-chamber bags, the patient must break a seal to enable the additive to run to the base solution. It happens sometimes that the patient does not properly open the seal or forgets to open the seal completely. In such a case, therapy does not take place properly. What is needed is a better way to insure that the seal has been broken and the liquids in the chambers properly mixed before use by a patient. 
         [0012]    It is therefore desirable to have a ready apparatus to organize and support multiple solutions bags sequentially or simultaneously such that a sensor can determine whether one of the chambers in the bags has been broken prior to use, and thus mixed. 
       SUMMARY 
       [0013]    One embodiment, is a medical fluid supply bag stand. The medical fluid supply bag stand includes a support pole, at least one shelf movably connected to the support pole, the shelf configured for mounting only an upper portion of the medical fluid supply bag, and a sensor mounted on the shelf for sensing liquid in the upper portion of the supply bag, the sensor suitable for determining whether liquid is present in the upper portion. 
         [0014]    Another embodiment is a method of sensing a medical fluid. The method includes steps of providing a medical fluid supply bag stand, wherein at least one shelf is movably connected to the stand, the at least one shelf configured for mounting only a portion of a medical fluid supply bag, the medical fluid supply bag having at least two chambers. Another step is mounting only one chamber of the medical fluid supply bag on the at least one shelf, and sensing a presence of the one chamber with a sensor mounted on the at least one shelf. Another step is sensing an absence of liquid in the one chamber if a seal separating the at least two chambers leaks or has been broken. 
         [0015]    In another embodiment, the method further comprises connecting the supply bag to a dialysis apparatus selected from the group consisting of: a continuous ambulatory peritoneal dialysis apparatus, an automated peritoneal dialysis apparatus, a hemodialysis apparatus, a hemofiltration apparatus, and a hemodiaflitration apparatus. 
         [0016]    Another aspect is a medical fluid supply bag stand. The medical fluid supply bag includes a base, a support pole mounted on the base, and a plurality of shelves in a vertical row, each shelf movably connected to the support pole, and each shelf configured for mounting only a portion of a medical fluid supply bag, and a sensor mounted on each shelf for sensing liquid in an upper portion of the medical fluid supply bag, the sensor suitable for determining whether a leak has developed in the supply bag. 
         [0017]    Additional features and advantages are described herein, and will be apparent from, the following Detailed Description and the figures. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0018]      FIG. 1   a  shows a medical fluid bag stand with a vertical row of a plurality of shelves. 
           [0019]      FIG. 1   b  shows the medical fluid bag stand of  FIG. 1   a  with a medical fluid bag loaded onto each of a plurality of shelves. 
           [0020]      FIG. 2  depicts a shelf according to the embodiment of  FIGS. 1   a  and  1   b  with a sensor mounted on the shelf. 
           [0021]      FIG. 3  depicts a side view of the shelf embodiment of  FIG. 2 ; and 
           [0022]      FIG. 4  depicts a more detailed view of a second embodiment of a shelf. 
       
    
    
     DETAILED DESCRIPTION 
       [0023]    The present disclosure includes an apparatus and method for supporting one or more medical fluid supply bags during treatment as well as testing such bags to sense and determine whether a seal has been broken, such that fluids flow from one chamber to a second chamber prior to treatment. The stand and method of testing described herein apply to any medical fluid treatment using supply bags having multiple chambers. The apparatus and methods described herein are particularly applicable to dual-chamber bags in which fluids or constituents within the chambers are mixed at the time of therapy. In particular, the stand and test method are well suited for renal failure. For example, the stand and test method are well suited for CAPD, APD, hemodialysis, hemofiltration, hemodiofiltration and any combination thereof. The stand and the method described herein will also suffice for detecting leakage in single-chamber bags. 
         [0024]    The present disclosure is intended to address shortcomings in the use of the prior art, such as dual chamber bags made with a heat seal and disclosed by Richmond et al., in U.S. Pat. No. 4,465,488, and Balteau et al., in U.S. Pat. No. 5,431,496, the entire disclosures of which are hereby incorporated by reference in their entirety. As noted, the systems and methods described herein may be used to insure proper mixing of the dialysate liquid components before they are administered to patients. In addition, the seals between chambers can leak and if mixing occurs too soon, the potency and effectiveness of the mixed solution may not be as intended. Accordingly, the present disclosure has discovered unique, inexpensive ways to discover leaks or unintended, premature mixing and to alert users to the situation. 
         [0025]      FIGS. 1   a  and  1   b  depict perspective views of a first embodiment of a bag stand. As seen in  FIG. 1   a,  the stand  10  includes a base or pedestal  12 , a central pole or stand  14 , a plurality of shelf supports  16 , and a matching plurality of shelves  18  supported on the shelf supports. Each shelf has a sensor  22  for sensing the presence of a container of liquid, such as a 2 L or 5 L bag of dialysis liquid.  FIG. 1   b  depicts the same stand  10  with a plurality of bags  20  mounted on the shelves, one bag per shelf. 
         [0026]    The stand and its components may be made from metal, such as steel alloys, aluminum or aluminum alloys. These strong materials may be needed for the strength and rigidity of the stand. A 5 L bag of dialysis fluid, containing mostly water, contains about 5 kg (about 11 pounds) of water along with the weight of the package, the seals, tubing, and so forth. A rack with only 5 bags, as depicted in  FIG. 1   b,  thus must support over 25 kg (over 55 pounds), in addition to the weight of the shelves, brackets, supports, and so forth. The stand must thus be sturdy. In addition to the metals mentioned above, the stand and its components may be made from plastic, such as engineering plastics, especially fiber-reinforced plastics, such as fiberglass reinforced nylon, and the like. 
         [0027]      FIGS. 2 ,  3 , and  4  depict closer views of the component parts of the stand.  FIG. 2  depicts a shelf support  16  with a hook or attachment for holding an orifice from a bag. Shelf  18  includes a sensor  22  for detecting the presence of a bag on the shelf. The shelf may be made of sheet metal as shown, but instead may be made of sturdy wire or plastic mesh, or other material capable of supporting a bag of dialysis fluid. The sensor is depicted on the top surface of the shelf. However, it is also possible for the sensor to be mounted on the underside of the shelf. As shown below, the shelf may also include an orifice or cutout on its top surface so that the top surface of sensor  22  is flush with the top surface of the shelf. As best shown in  FIG. 3 , the shelf mounts to the central pole at an acute angle A from vertical. 
         [0028]    The sensor may be any sensor capable of sensing a bag of fluid, or a portion of a bag of fluid. As shown in  FIG. 1   b,  the bag  20  may rest on the shelf, or as shown in  FIG. 3 , a lower portion of the bag  20   a  may hang while an upper potion  20   b  rests on the shelf itself. In either version, sensor  22  will sense the presence of the bag  20  or its upper portion  20   b.  Sensor  22  may be a capacitive sensor, sensing the presence of plastic, with a dielectric constant of about 2-6, or water, with a dielectric constant of about 80, rather than air, with a dielectric constant of just over unity. If the frangible or heat seal between the bag portions leaks or is broken so that the liquid may be administered to a patient, the liquid in the upper bag will flow into the lower bag. The sensor will then sense a different dielectric constant after a period of time, such as very quickly for proper mixing, or over several minutes or longer for an inadvertent leak. The sensor is in communication with a system controller or with a separate controller or logic circuit for the bag stand. The change in dielectric constant will be interpreted as a decrease in liquid, due either to proper mixing or to a leak. The controller or logic circuit will send a signal to alert the patient or a caregiver that a decrease has occurred. The decrease in liquid is desirable and required for proper administration of peritoneal dialysis liquid. However, a decrease in liquid at any other time, such as a decrease caused by a leak, is undesirable and should be brought to the attention of the patient or the caregiver. 
         [0029]    A capacitive sensor may be calibrated or adjusted to detect this difference as it is positioned on the top side of the shelf or on the bottom side. A bottom side position will not interfere with frequent and rough placement of the bag on the shelf, and may yield longer life for the sensor and the stand. Suitable capacitive sensors include those available from Omron Corporation, Tokyo, Japan. Some sensors are equipped with their own electronics and thus are easy to calibrate and place in service. Capacitive sensors with a sensing range of about 10 mm are excellent in this application. 
         [0030]    In addition to capacitive sensors, other suitable sensors include optical sensors that will sense the presence or absence of liquid between a source of light and a light detector. Ultrasonic sensors, which return a signal that depends on reflection of sound waves by an object, are also suitable and may be used. Pressure sensors on a top surface of the shelf, sensing a pressure on the shelf caused by the bag or the upper portion of the bag, may also be used. There are many types of pressure sensors that are suitable for this application. 
         [0031]    In this embodiment, shelf stand central pole  16  is in the shape of a hollow square, which is mounted in the base or pedestal, as seen in  FIG. 1   a.  Shelf support  16  in this embodiment is shaped as a hollow rectangle with an inside that is slightly larger than the outside of the central pole, so that each shelf support can be placed over the central pole and slid down upon it. As shown in  FIG. 4 , a pin  28  or other fastener is placed above each shelf support, as it is placed on the pole, the pin used to support the next shelf support that is so placed. Because the shelf supports are only slightly larger than the pole itself, no rocking or back-and-forth motion is possible, and thus only a single pin is needed for each support. Of course, the pin must be able to support the entire shelf, shelf support, and the weight of a bag of liquid, such as a 5 L bag of dialysis fluid. 
         [0032]      FIG. 4  depicts a more complete version of a partial cross section of a stand central pole  14 , a shelf support  32 , and a shelf  18 . The central pole  14  includes a plurality of vertically spaced orifices  14   a,  each pair of orifices suitable for insertion of a pin  28 , the pin suitable for supporting a shelf support  32 , as shown. The shelf support includes a hollow, rectangularly-shaped portion for placing about the central pole  14 . The support also includes a support portion  30 . Support portion  30  is inclined at an angle from about 30 to 60 degrees from the horizontal and includes a hinge  34  at its upper portion the hinge connecting shelf  18  to the shelf support  28 . The shelf includes a hook  36  or other attachment for holding a bag of liquid. As noted previously, shelf  18  may include a recess  24  on its top surface for mounting a sensor, so that a top surface of the sensor is very close to a top surface of the shelf itself. Other shapes may be used. For example, it may be easier to arrange bags if the central pole has a circular cross-section, and each shelf support also has a circularly-shaped inner diameter. With this configuration, each shelf support may be rotatable about the central pole, and it may be easier to place a subsequent bag if each shelf support is easily rotatable and movable. 
         [0033]    In use, if the bag contains a frangible or heat seal that breaks, liquid from the upper portion will leak into the lower portion. An ultrasonic or capacitive sensor will detect a lower level of liquid in the bag. A pressure sensor will also detect a lower level of liquid in the bag since a lower pressure will be sensed. If an optical sensor is used, it will more freely pass light at a given distance above the shelf surface. At least the capacitive sensor may be used on the lower surface of the shelf as well as the upper surface of the shelf. 
         [0034]    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 subject matter and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the appended claims.