Abstract:
A dialysis disposable sterilization apparatus includes a connector and a protective cap fitted to the connector. The apparatus also includes a sealing ring provided by one of the protective cap or the connector, the sealing ring forming a seal between the cap and the connector, the seal capable of holding pressure. The apparatus further includes a stabilization rib provided by the connector, the stabilization rib positioned and arranged to (i) tend to prevent the protective cap from vibrating about the sealing ring and (ii) enable a sterilizing gas to flow past the stabilization rib to contact the sealing ring.

Description:
PRIORITY CLAIM 
     This application claims priority to and the benefit as a continuation application of U.S. patent application Ser. No. 12/560,022, now U.S. Pat. No. 8,617,465, filed Sep. 15, 2009, entitled, “DIALYSIS CONNECTOR AND CAP COMPATIBLE WITH GAS STERILIZATION”, the entire contents of which are hereby incorporated by reference and relied upon. 
    
    
     BACKGROUND 
     The present disclosure relates to sterile medical fluid delivering and in particular to the delivering of a dialysis solution. 
     Due to disease 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. 
     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. One who has failed kidneys could not continue to live without replacing at least the filtration functions of the kidneys. 
     One type of dialysis is peritoneal dialysis. Peritoneal dialysis uses 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. 
     There are various types of peritoneal dialysis therapies, including continuous ambulatory peritoneal dialysis (“CAPD”) and automated peritoneal dialysis (“APD”). 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 patient&#39;s 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. 
     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 four hours. APD is similar to CAPD in that the dialysis treatment includes a drain, fill, and dwell cycle. APD machines, however, perform three to four cycles of peritoneal dialysis treatment automatically, typically overnight while the patient sleeps. Like CAPD, APD machines connect fluidly to an implanted catheter, to one or more sources or bags of fresh dialysate and to a fluid drain. 
     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. 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. 
     Delivery of dialysis fluid to the patient needs to be as germ free as possible. Germs or pathogens reaching the patient&#39;s peritoneum can cause peritonitis. Peritonitis can cause the patient to feel extreme pain and if not treated properly can result in death. Different methods of sterilization are available, such as gamma radiation and ethylene oxide (“EtO”) gas. Gamma radiation is advantageous because it works from the outside-in, such that the radiation can sterilize the interior surfaces of a structure that trap a volume of gas within the sterilized part, such as a cap. 
     Gamma radiation does however have some negative side effects. One side effect is that the sterilized part, e.g., clean medical grade plastic, tends to yellow. While such yellowing is not harmful to the patient, some patients may find the yellowed disposable part less aesthetically pleasing than a pristine looking clear plastic disposable. Second, gamma radiation can cause the sterilized part to have an odor, especially when the disposable has larger plastic surfaces, which can also be displeasureable to the patient. 
     A need therefore exists for an apparatus and method for sterilizing a sealed part, such as a cap, using a sterilizing gas, such as EtO. 
     SUMMARY 
     The present disclosure sets forth an apparatus and method for sterilizing (or at least substantially sterilizing) a sealed component or one component sealed to another component, such that they form a sealed compartment capable of holding a positive or negative pressure. The present apparatus and method are illustrated as using a tip protector, or cap, which encloses a fluid connector, such as a peritoneal dialysis fluid connector. The connector is illustrated as being a spike connector but does not have to be a spike connector and instead could be a female connector that becomes spiked by an external spike connector. The connector could extend from a disposable cassette directly or alternatively from a line or tube attached to the disposable cassette. Further alternatively, the connector could extend from a tube or pigtail that is attached to a supply bag, heater bag or drain bag. As will be appreciated from the following summary and description, the present system and method are not limited to a cop/connector combination and instead may be applied to other closed volumes found in medical fluid disposables, such as dialysis disposables. 
     In one embodiment, the base of the tip protector or cap includes a sealing rib or ring that extends fully around the inside wall of the cap. This sealing rib press-fits against an outer annular wall of the connector or spike tip. The press-fit is sufficient to hold a specified pressure, e.g., eight psig. While the sealing ring provides the necessary seal, additional structure on the inside wall of the cap is needed to contact the connector or spike to prevent the cap from vibrating with respect to the spike during shipping or otherwise prior to its use. This additional structure is formed so as not to create a separate sealed volume with the sealing rib or ring. For example, the structure could be an additional rib or ring that is not extend fully around the inside wall of the cap. In one embodiment, the additional structure is a segmented, discontinuous or semi-continuous rib or ring that extends around the inside wall of the cap. The semi-continuous ring can for example have notches or grooves to provide openings through the opening, and the press by the semi-continuous ring to reach one side of the base, continuous sealing ring. The additional rib does not thereby create a separate, trapped sealed volume with the base ring when the cap is press-fitted onto the connector or spike. 
     Alternatively, the additional structure is a vertical or slanted rib extending along the inner wall of the cap or tip protector. For example, the rib can be a spiraling rib that allows the sterilizing gas to thread or corkscrew its way to the sealing rib. 
     In yet another alternative embodiment, the sealing ring and/or any of the additional vibration stabilizing structures can be provided on the outer walls of the connector or spike instead of being provided on the inner wall of the cap or tip protector. 
     The above apparatus enables a method of sterilization to take place in which the outside of the cap is exposed to sterilizing gas such as ethylene oxide (“EtO”), which contacts and sterilizes or at least substantially sterilizes the underside of the sealing ring or rib, namely, the rib extending all the way around the cap. Sterilizing gas is also flowed through the connector or spike, around the outside of the connector, through the openings in (or around) the additional stabilizing structures to reach the opposing side of the sealing ring for sterilization. It has been found that line contact between the cap or tip and the connector or spike, which the sterilizing gas may not reach, does not pose a risk to the patient. 
     It is accordingly an advantage of the present disclosure to provide an improved apparatus and method for gas, e.g., EtO sterilization. 
     It is another advantage of the present disclosure to provide an improved apparatus and method for sterilizing (at least substantially) inner walls of a cap sealed to a disposable cassette or set. 
     It is a further advantage of the present disclosure to provide an improved apparatus and method for sterilizing (at least substantially) a sealed surface. 
     Additional features and advantages are described herein, and will be apparent from the following Detailed Description and the figures. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  is a perspective view of a disposable cassette having multiple port connectors that receive protective caps until the caps are removed so that a dialysate supply bag can be connected to the connector. 
         FIG. 2  is a side-sectional view of one of the connectors of the disposable cassette, wherein the connector is a spike connector that penetrates a female connector at the end of a supply bag tube. 
         FIG. 3  is a side-sectional view illustrating one embodiment of a connector/cap construction of the present disclosure. 
         FIG. 4  is a side-sectional view illustrating another embodiment of a connector/cap configuration of the present disclosure. 
         FIG. 5  is a sectional elevation view illustrating a further embodiment of a connector/cap configuration of the present disclosure. 
         FIG. 6  is a schematic elevation view illustrating yet another embodiment of a connector/cap configuration of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to drawings and in particular  FIGS. 1 and 2  disposable dialysis fluid pumping cassette  10  and corresponding supply connectors are illustrated. Pumping cassette  10  is operable in one embodiment with a peritoneal dialysis cycler as set forth in U.S. Pat. No. 7,955,295, filed Jul. 5, 2007, entitled “Fluid Delivery System With Autoconnect Features”, the entire contents of which are incorporated herein by reference. Other relevant peritoneal dialysis machines are set forth in U.S. Pat. Nos. 5,350,357 and 7,410,175, the entire contents of each of which are incorporated herein by reference. While cassette  10  is described as being operable with a peritoneal dialysis machine, cassette  10  is alternatively operable with a different type of medical fluid machine, such as hemodialysis, hemofiltration or hemodiafiltration machine. 
     Still further alternatively, the connector and cap set forth herein does not extend from a cassette, such as cassette  10 , but extends rather from an end of a tube, such as a supply bag tube or pigtail that extends from a supply bag  10  or container. The tube can alternatively can be attached to the cassette, such as cassette  10 , wherein the connector and cap are placed at the distal non-cassette end of the tube. 
     Cassette  10  in the illustrated embodiment includes a rigid portion  12  and a pair of flexible sheets  14   a  and  14   b  welded to or otherwise sealed to rigid portion  12 . Flexible sheets  14   a  and  14   b  are operated mechanically and/or pneumatically to open and close pumps and valves as disclosed in the above referenced patents. Rigid portion  12  includes a sidewall  16  and a base plate  18 . Various structures arise from base plate  18 , such as pumping chambers  20  and flow paths  22 . Valve chambers, not illustrated because they reside on the other side of base plate  18 , also extends out from the base plate  18 . 
     In the illustrated embodiment, cassette  10  also includes an integrated inline heater  24 . Cassette  10  includes a pair of ports  26   a  and  26   b  that are preattached to tubing that leads for example to a drain line or patient line. If batch heating is used instead of inline heating here via inline heater  24 , the preattached tubing can run to a heater bag alternatively. 
     Cassette  10  further includes a plurality of shrouds  28  that extend outwardly from base plate  18 . Although shrouds  28 , and connectors  30  protected by the shrouds, are shown extended perpendicular to base plate  18 , the connectors  30  and shrouds  28  can extend alternatively perpendicularly from sidewall  16 . In another alternative embodiment, shrouds  28  are not provided and connectors  30  are instead exposed. In one embodiment, connectors  30  each connect to a supply line running from a dialysis fluid container or bag. 
       FIG. 2  illustrates connector  30  and shroud  28  in more detail. Connector  30  is illustrated having a base portion  32  that extends to a spike  34 . Base section  32  and spike tip  34  define an interior lumen  36 , which allows liquid from a supply bag to enter cassette  10 .  FIG. 2  illustrates that a supply bag connector  40  includes a female head  42 , having a sheet or membrane that is pierced by spike  34  of connector  30 . Connector  40  includes a body  44  that is sealed to an end of a supply tube  46 . It should be appreciated that connector  30  does not have to be a spike connector and instead can be a female connector that is pierced by supply bag connector  40 . In any case, once fluid communication is established between connectors  30  and  40 , fresh dialysate or dialysis solution can flow from a supply bag or container (not illustrated) through supply tube  46 , body portion  44  of female connector  40 , lumen  36  of spike connector  30  and into cassette  10 . 
     Referring now to  FIG. 3 , prior to spiking connector  40 , a tip protector  50  is removed from spike connector  30 . Tip protector  50  protects connector  30  and also seals the connector such that it can be sterilized. Again, connector  30  may be provided in different locations, such as the end of a supply tube. Even so, a tip protector, such as tip protector  50 , is typically provided. 
     Tip protector  50  provides or includes a sealing ring  52  that extends continuously for 360 degrees around an inner wall of  54  of tip protector  50 . Sealing ring  52  press-fits against an outer wall  38  of spike connector  30 . The press-fit is configured to hold a desired amount of positive or negative pressure, such as plus or minus eight psig. That is, if the inner lumen  37  is pressurized with air or a sterilizing gas, such as ethylene oxide (“EtO”), lumen  56  between inner wall  54  of cap or tip protector  50  and outer wall  38  of spike  30  also becomes pressurized. Sealing ring  52  is configured to hold that pressure, for example, up to eight psig. 
     Tip protector  50  also includes or defines one or more stabilizing rib  58   a  and  58   b . Without stabilizing ribs  58   a  and  58   b , tip protector  50  will vibrate about sealing ring  52  when cassette  10  and associated disposable components shipped along with the cassette are transported or moved. Such vibration can cause cap or tip protector  50  to loosen or come free from connector  30 . 
     Stabilizing ribs  58   a  and  58   b  contact outer wall  38  of connector  30  and prevent such vibration from occurring. Although two stabilizing ribs  58   a  and  58   b  are illustrated, it should be appreciated that only one stabilizing rib or more than two stabilizing ribs may be provided as desired. Also, stabilizing ribs  58   a  and/or  58   b  may be moved further towards the distal end of tip protector  50  and connector  30 . 
     Stabilizing ribs  58   a  and  548   b  are not continuous about inner wall  54  of tip protector  50  and instead are provided in segments about the inner wall and outer wall  38  of connector  30 . That is, one or more opening  60  is provided through, within, or otherwise separating the structure of stabilizing ribs  58   a  and  58   b . Openings  60  may provide a total opening that can be as low the micron level around the circumference of inner wall  54  of tip protector  50 . That is, the structure of stabilizing ribs  58   a  and  58   b  may virtually all the way around the entire inner circumference of tip protector  50 . 
     The purpose of openings  60  is to allow sterilizing gas to be introduced up through the lumen  36  of spike connector  30 , out around outer wall  38  and through lumen  56 , through the openings  60 , such that sterilizing gas impinges and sterilizes (or substantially sterilizes) a surface  52   a  of sealing ring  52 . Such flow path is illustrated by the phantom line arrow shown in  FIG. 3  starting as the centerline of connector  30  and cap  50 . 
     At the same time or at a different time, sterilizing gas is flowed around outer wall  62  of tip protector  50  as shown by the other arrowed phantom line. This outside gas impinges and sterilizes (or substantially sterilizes) surface  52   b  of sealing ring  52 . In this manner, virtually all of sealing ring  52  is sterilized (or substantially sterilized) via a sterilizing gas, such as EtO. It should be noted that in a similar manner, stabilizing ribs  58   a  and  58   b  also include line contacts to the spike connector  30  and thus have the same method of sterilization as ring  52  in which sterilizing gas contacts both sides of ribs  58   a  and  58   b  at the line contact, but may not actually impinge the line contacts. 
     It has been found that the line contact between sealing ring  52  and outer wall  38  (and thus ribs  58   a  and  58   b  and outer wall  38 ), which may not be not impacted by the sterilizing gas, does not pose any significant risk of contamination. It is contemplated to provide the sterilizing gas onto surfaces  52   a  and  52   b , sequentially or at the same time, depending upon ease of flowing the gas. Cassette  10  and the associated bags and tubes of the entire disposable set are provided inside of a bag or container that holds the sterilizing gas supplied on the outside of cassette  10  and tip protector  50 . 
     Referring now to  FIG. 4 , an alternative connector  130  and alternative cap  150  are illustrated. Connector  130  and cap  150  are the same as connector  30  and cap  50 , respectively, of  FIG. 3  except that in  FIG. 4 , alternative sealing rings  152  and alternative stabilizing ribs  158   a  and  158   b  are provided on the outer surface  38  of connector  130 . As seen by the phantom arrows, sterilizing gas, such as EtO flows in the same pathways as discussed above to contact surfaces  152   a  and  152   b  of alternative sealing ring  152 . 
     Referring now to  FIG. 5 , a further alternative embodiment of the cap or tip protector is illustrated by cap  250 . Cap  250  can operate for example with connector  30  shown in  FIG. 3 . Cap  250  includes the sealing ring  52  shown above in  FIG. 3 , which compresses against outer wall  38  of connector  30  to create a press-fit seal that holds a desired pressure. Sealing ring  52  includes surfaces  52   a  and  52   b  to be sterilized as described above. 
     Alternative vertical stabilizing ribs  258   a  and  258   b  extend inwardly from inner wall  54  of cap  250 . The vertical ribs  258   a  and  258   b  allow sterilizing gas to proceed down along inner wall  54  through lumen  56 , as seen by the phantom arrowed line, to impinge surface  52   a  of sealing ring  52  and sterilize (or at least substantially sterilize) surface  52   a . Surface  52   b  is impinged via a sterilizing gas from beneath as shown via the upwardly directed arrowed line in  FIG. 5 . As before, ribs  258   a  and  258   b  are provided alternatively on outer wall  38  of connector  30 . 
     Referring now to  FIG. 6 , a further alternative cap  350  is illustrated having a spiral or threadlike stabilizing rib  358 . Here, as seen via the arrowed phantom line, sterilizing gas, such as EtO, spirals or winds its way around the corkscrew or threadlike spiral rib  358  until it reaches the end of the spiral rib and impinges sealing ring  52 . Sealing ring  52  is also contacted via the sterilizing gas beneath as has been described herein. 
     Suitable materials for cassette  10  include a cyclic olefin copolymer (“COC”) or a blend of COC with another olefin or acrylic, or other medically suitable relatively rigid plastic that can be sterilized via gas. Suitable materials for connectors  30  and  130  include any of the materials discussed above for cassette  10 . Suitable materials for caps  50 ,  150 ,  250  and  350  include low density polyetylene (“LDPE”) or a relatively softer or low density, olefin that may be semipermeable to EtO. Each of the structures discussed herein can be blow molded or injection molded. 
     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.