Abstract:
A bidirectional valve for medical use or the like provides different threshold opening pressures in different directions using a valve seat and flapper construction providing improved characterization in operation in contrast to cross-slit valves often used for bidirectional operation. A valve disk supported in a central annular region provides movable portions engaging in valve seats at a peripheral region and a central region.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present invention claims the benefit of U.S. provisional application 61/835,821 filed Jun. 17, 2013 and hereby incorporated by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to normally closed valves providing for bidirectional flow above predetermined pressures. 
       BACKGROUND OF THE INVENTION 
       [0003]    Vascular access catheters may be inserted into a patient to permit the infusion of liquid and drugs into the patient&#39;s blood supply and for periodic sampling of the patient&#39;s blood. A needle-free system may provide a luer or similar connector at the distal end of the catheter to allow a syringe or IV set to be attached to or removed from the catheter as desired. 
         [0004]    When the catheter is not connected to an infusion or sampling device, it is important that it can be closed to prevent the introduction of contaminants into or loss of blood out of the catheter. For this purpose, it is known to place a bidirectional valve in series with the luer connector that opens only under predetermined threshold pressures associated with infusion into the patient or sampling of blood from the patient. 
         [0005]    A common bidirectional valve of this type provides a dome, for example, fabricated of silicon rubber, having a cross-slit that opens under pressure. The dome provides for different threshold pressures for opening the slit depending on the direction of flow, with flow into the concave side of the dome occurring at a lower pressure than flow into the convex side of the dome. Normally it is desired that the infusion threshold pressure be lower than the aspiration or blood sampling pressure. 
         [0006]    When blood is drawn out through such a catheter valve, it is normally desired to flush the valve mechanism with a counter-flow of an infusion liquid such as saline solution. In this respect, it is important that the flushing saline flow occur along substantially the same path as that to which the blood flowed. 
         [0007]    A slit dome valve provides a relatively simple mechanism to generate a bidirectional valve opening under different predetermined pressures associated with different flow directions. Nevertheless, fabrication of the slit valve can be problematic. If the slit is not cut perfectly, the resulting valve may leak under low pressure or exhibit significant variations in threshold pressure. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention provides a normally closed bidirectional valve permitting different threshold pressures with direction of flow, yet avoiding the problems associated with cross slit dome and other similar slit valves. Different regions of a valve disk open and close against different valve seats providing two valve systems associated with different flow directions. The valve systems communicate with valve ports via an overlapping channeling system so that a path of sampled or aspirated blood is fully traversed by the counter-flowing path of flushing or infusing liquid to clean the valve of blood product. 
         [0009]    Specifically, in one embodiment, the invention provides a normally closed bidirectional valve having a housing with a first and second port communicating with an internal housing volume. An elastomeric disk is disposed between the first and second port in the internal housing volume, and retained against the housing within an annular region of the elastomeric disk between a central region and an outer peripheral region. In this way, a central region and outer peripheral region of the valve disk are free to move with respect to the housing. The housing provides a first valve seat engaging the outer peripheral region of the elastomeric disk when the elastomeric disk is in a relaxed state and a second valve seat engaging the central region when the elastomeric disk is in a relaxed state. In addition, the housing provides first flow channels leading from the first port to the elastomeric disk to press the elastomeric disk against the second valve seat and to press the elastomeric disk away from the first valve seat when pressure at the first port is greater than pressure at the second port. The housing further provides second flow channels leading from the second port to the elastomeric disk to press the elastomeric disk against the first valve seat and to lift the elastomeric disk away from the second valve seat when pressure at the second port is greater than pressure at the first port. 
         [0010]    It is thus a feature of at least one embodiment of the invention to provide a valve using a robust, easily manufacturable and well-defined valve seat and valve flapper combination as opposed to a less predictable and more difficult to manufacture cross slit dome valve design. 
         [0011]    The elastomeric disk may interact with the first and second valve seats to provide for a first threshold opening pressure at which fluid flows between the first port and the second port and a second threshold opening pressure different from the first threshold opening pressure when the fluid flows between the second port and the first port. 
         [0012]    It is thus a feature of at least one embodiment of the invention to provide improved control over the valve openings in different flow directions by providing distinct valve structures for those different flow directions. 
         [0013]    The first threshold opening pressure may permit gravity flow of intravenous liquids from a standard IV bag. 
         [0014]    It is thus a feature of at least one embodiment of the invention to provide an extremely low opening pressure suitable for infusion. 
         [0015]    In addition or alternatively, the threshold opening pressure may be less than 20 millibars and the second threshold opening pressure is greater than 2 bars. In addition or alternatively, the difference between the first and second threshold opening pressures may be a factor greater than 100. 
         [0016]    It is thus a feature of at least one embodiment of the invention to provide a valve that offers a large difference in threshold opening pressures depending on direction. 
         [0017]    The elastomeric disk may be comprised of a first and second elastic material of different elasticity. 
         [0018]    It is thus a feature of at least one embodiment of the invention to provide greater flexibility in setting different threshold opening pressures by providing the ability to control not only the geometry of the valve disk but also the valve disk materials. 
         [0019]    The first elastic material of greater elasticity may form the outer peripheral region of the elastomeric disk contacting the first valve seat and the second elastic material of lesser elasticity may form the central region contacting the second valve seat. 
         [0020]    It is thus a feature of at least one embodiment of the invention to provide a readily manufactured dual-material elastomeric disk having a relatively simple circumferential seam line. 
         [0021]    The first flow channel may substantially overlap an entirety of the second flow channels to provide cleaning of the valve with flow from the first port. 
         [0022]    It is thus a feature of at least one embodiment of the invention to provide a valve where infusion liquid may cleanse the valve of blood material after aspiration or blood sampling. 
         [0023]    Fluid flow may enter the first port in a first direction toward a first side of the elastomeric disk and the valve may include a diverter wall directing flow from the first port opposite the first direction toward a second side of the elastomeric disk. 
         [0024]    It is thus a feature of at least one embodiment of the invention to provide directed flushing in the contact regions of the valve operating during blood flow. 
         [0025]    The elastomeric first and second valve seats may provide substantially circular and concentric contact lines between the valve seat and the elastomeric disk. 
         [0026]    It is thus a feature of at least one embodiment of the invention to provide two distinct valve structures for different flow directions using a single elastomeric disk component. 
         [0027]    The first and second valve seats may be ridges contacting opposite sides of the elastomeric disk. 
         [0028]    It is thus a feature of at least one embodiment of the invention to provide a simple valve structure that can be realized with fewer components. 
         [0029]    Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims and drawings in which like numerals are used to designate like features. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0030]      FIG. 1  is a fragmentary perspective view of a bidirectional valve of the present invention providing, in one application, a needle-free connection to a syringe for drawing a blood sample; 
           [0031]      FIG. 2  is a perspective view of an elastomeric disk used to provide bidirectional fluid control in a first embodiment of the invention; 
           [0032]      FIG. 3  is a perspective view of a support for the elastomeric disk of  FIG. 2 ; 
           [0033]      FIG. 4  is a cross-section along line  4 - 4  of  FIG. 1  of the first embodiment of the invention showing a normal closed state of the valve; 
           [0034]      FIG. 5  is a figure similar to that of  FIG. 4  showing deformation of a central region of the elastomeric disk to open the valve in a sampling/aspiration direction, for example, for the withdrawal of blood; 
           [0035]      FIG. 6  is a figure similar to that of  FIGS. 4 and 5  showing deformation of a an outer portion of the elastomeric disk to open the valve in a flushing/infusion direction; 
           [0036]      FIG. 7  is a plot of pressure as a function of flow through the valves of the present invention showing the ability to obtain different “cracking” pressures at which flow first begins with different directions of flow; 
           [0037]      FIG. 8  is a figure similar to  FIG. 4  of an alternative embodiment of the valve having fewer housing components and showing the normal closed state of the valve; 
           [0038]      FIG. 9  is a figure similar to  FIG. 8  showing deformation of the central region of the elastomeric disk to open the valve in a sampling/aspiration direction, for example, for the withdrawal of blood; 
           [0039]      FIG. 10  is a figure similar to that of  FIG. 8  showing deformation of an outer peripheral region of the elastomeric disk to open the valve in a flushing/infusion direction; 
           [0040]      FIG. 11  is a fragmentary detail of alternative embodiment of the invention showing a diverter wall for reversing flow of infusion liquid for improved cleaning; and 
           [0041]      FIG. 12  is a fragmentary detail of an alternative embodiment of the invention showing a dual elastomeric disk. 
       
    
    
       [0042]    Before the embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use of “including” and “comprising” and variations thereof is meant to encompass the items listed thereafter and equivalents thereof as well as additional items and equivalents thereof. 
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0043]    Referring now to  FIG. 1 , a bidirectional valve  10  per the present invention may be attached at a lower end  12  to a flexible catheter  14  communicating with a patient  15  (not shown) to provide for vascular access, for example, through a needle or the like placed in the patient  15 . The lower end  12  of the bidirectional valve  10  may provide for a standard needle-free tubing connector  17 , as known in the art, providing, for example, a tube of the flexible catheter  14  with a frustoconical outer surface receiving the IV line and expanding it into a barbed collar around the tube. 
         [0044]    An upper end  16  of the bidirectional valve  10  may provide for a needle-free luer connector  18  such as a female luer lock or luer slip connector that may receive a corresponding connector  20  of a syringe  22 , for example, for flushing, sampling or aspiration. Alternatively, the upper end  16  may receive a corresponding connector of an IV bag, infusion pump, or the like (not shown). 
         [0045]    Referring now to  FIGS. 2, 3 and 4 , the valve  10  may provide a housing  42  constructed of one or more rigid components integrally molded or fixedly assembled together to define a cavity  28  positioned between an upper channel  48  of the needle-free luer connector  18  and a lower channel  50  of the needle-free tubing connector  17 . Generally channels  48  and  50  are aligned and coaxial along an axis  30  and the cavity  28  positioned to receive and conduct fluid flow passing between needle-free luer connector  18  and needle-free tubing connector  17 . The cavity  28  and housing  42  may be radially symmetric about axis  30 . 
         [0046]    The cavity  28  may include a flexible valve element, such as an elastomeric diaphragm  24 , for example, fabricated of injection molded silicone rubber or the like. In this embodiment, the elastomeric diaphragm  24  may be a substantially planar circular disk extending generally perpendicular to an axis  30  of fluid flow and is centered and radially symmetric about that axis  30 . 
         [0047]    The elastomeric diaphragm  24  may provide an outer peripheral region  32  positioned around a central region  34 . A mounting rim  40  may extend upward from an intermediate annular region  35 , the latter separating the outer peripheral region  32  from the central region  34 . The mounting rim  40  is received into a socket in the housing  42  to retain the intermediate annular region  35  substantially fixed with respect to the housing  42  while allowing the peripheral region  32  and central region  34  to move with respect to the housing  42 . 
         [0048]    The central region  34  in this case provides a circular blocking disk  37  attached to an inner edge of the intermediate annular region  35  through flexible struts  36 . The flexible struts  36  extend radially and are separated to provide for flow passages  38  between the struts  36  within the inner edge of the intermediate annular region  35 . 
         [0049]    Natural resilience of the material of the elastomeric diaphragm  24  will hold a lower surface of the outer peripheral region  32  downward against an upwardly directed ridge of a valve seat  44 , the latter extending in a ring about axis  30  beneath the outer peripheral region  32 . The valve seat  44  may be supported by a support structure  45  separately molded and installed in the cavity  28  to be held between upper and lower cavity walls on peripheral crenellated flanges  43  which abut the upper cavity wall and lower cavity wall while providing for the passage of fluid between crenellations. The outer peripheral region  32  is outwardly cantilevered in a direction perpendicular to axis  30  and away from the mounting rim  40  of the intermediate annular region  35  so that it may flex upwardly away from the valve seat  44  or downwardly against the valve seat  44  depending on the direction of flow through the cavity  28  and the resulting differential pressure across the faces of the outer peripheral region  32 . 
         [0050]    The same natural resilience of the material of the elastomeric diaphragm  24  also will hold the blocking disk  37  of the central region  34  downward against an upwardly directed ridge of valve seat  46  extending in a ring concentrically within valve seat  44 . The material of the valve seats  44  and  46  are fixed with respect to the cavity  28  but provide passages therearound as will be described. 
         [0051]    Referring now to  FIG. 5 , the upper channel  48  of the valve  10  may communicate with a syringe  22 , for example, through a flow channel leading downward through the upper housing along axis  30  to the central region  34  of the elastomeric diaphragm  24 . This flow channel may proceed through passages  38  around the edges of the blocking disk  37  to a flow region between valve seat  46  and valve seat  44 . When an aspirating low pressure is applied to the upper channel  48 , for example, by a syringe  22 , the outer edge of blocking disk  37  and the corresponding struts  36  flex so that the outer edge of the blocking disk  37  rises away from valve seat  46  allowing fluid to be drawn through flow channels in the housing  42  from a lower channel  50 , upward around the valve seat  46  and around the blocking disk  37  through the flow passages  38  into the upper channel  48 . It will be appreciated that this flow only occurs when there is sufficient pressure difference between lower channel  50  and upper channel  48  to flex the central region  34  away from valve seat  46 . 
         [0052]    Referring to  FIG. 7 , the upward flow described above represents a negative pressure as depicted in  FIG. 7  and requires threshold opening pressure  47  (cracking pressure) to be exerted against the blocking disk  37  before the blocking disk  37  will rise sufficiently from the valve seat  46  to allow passage of fluid through the passages  38  as indicated by graph line  39 . When the magnitude of the negative pressure difference between lower channel  50  and upper channel  48  is below the necessary threshold opening pressure  47  needed to move the blocking disk  37 , the central region  34  remains in contact with seat  46  preventing flow between channels  50  and  48 . 
         [0053]    Referring now to  FIGS. 6 and 7 , when the pressure in upper channel  48  rises above the pressure of lower channel  50  by a threshold opening pressure  49  such as may occur during a flushing or infusion process, and as represented by positive pressure in  FIG. 7 , flow from the upper channel  48  may pass through the flow passages  38  and into the region between the valve seats  46  and  44 . This pressure causes an upward flexing of the outer rim of the outer peripheral region  32  causing it to rise away from valve seat  44  so that the flow may be received by a channel  51  passing beneath valve seats  46  and  44  into lower channel  50 . Generally, the threshold opening pressure  49  will differ from that of  47  and will desirably be much lower. This permits a low-pressure infusion while requiring a higher pressure for reversing flow to sample blood or the like preventing accidental flow reversal with minor pressure spikes in the IV line, for example, when the patient coughs. A threshold opening pressure is a pressure in which flow first begins when flow pressure is slowly increased from zero in a given direction. 
         [0054]    It will be noted that the path of fluid flow of  FIG. 6  passes on both sides of valve seat  46  and the elastomeric diaphragm  24  contacting valve seat  46  to flush away accumulated blood despite the separation of the flow paths of flushing/infusion versus sampling/aspiration. This flushing process is enhanced by diverter walls  53  which cause the flow of fluid during flushing/infusion to reverse direction with respect to axis  30  to flow upward in a direction opposite the downward direction of flow of fluid entering the upper channel  48 , for example, from an IV bag or the like. 
         [0055]    The present valve design can also be used in other IV set applications requiring bidirectional flow, e.g., designs allowing for pressure relief should the pressure downstream of the valve become very high rather than the application of a low-pressure aspiration on needle-free luer connector  18 . 
         [0056]    Referring now to  FIG. 8 , in an alternative embodiment, the central region  34  of the elastomeric diaphragm  24  may provide for a central circular opening  56  instead of the blocking disk  37  described above. As before an intermediate annular region  35  of the elastomeric diaphragm  24  may be stabilized against the housing  42  in this case by downwardly extending ribs  58  and upwardly extending ribs  60  cooperating with an increased thickness at the intermediate annular region  35 . 
         [0057]    In this embodiment, upwardly directed valve seat  44  is replaced with valve seat  62  extending downward from an upper wall of the housing  42  and in a ring about the axis  30  to abut and seal against the outer peripheral region  32  in a normal relaxed state. The central region  34  just outside of the opening  56 , in a relaxed state, contacts valve seat  64  formed as part of the housing  42  and also extends in a ring about axis  30  concentrically within valve seat  62  and is directed upward to contact the lower surface of the central region  34 . The valve seat  64  provides for multiple passages  68  around its periphery leading into lower channel  50  and is located directly beneath a portion of the elastomeric diaphragm  24  within the intermediate annular region  35  and outside of the valve seat  64 . 
         [0058]    Referring now to  FIG. 9 , when a low pressure is applied on the upper central upper channel  48  of the valve  10  (with respect to the pressure in channel  50 ), the inner periphery of opening  56  rises upward away from the valve seat  64  allowing passage of fluid from the lower channel  50  through passages  68  and opening  56  into upper channel  48 . As before, this flow only occurs when there is sufficient pressure difference between lower channel  50  and upper channel  48  to flex the central region  34  away from valve seat  46  thereby defining threshold opening pressure  47 . 
         [0059]    Referring to  FIG. 10 , when the pressure in upper channel  48  rises above the pressure of lower channel  50  by a threshold opening pressure  49  such as may occur during a flushing or infusion process, and as represented by positive pressure in  FIG. 7 , flow from the upper channel  48  may pass ribs  58  to press downward on the outer rim of the outer peripheral region  32  causing it to drop away from valve seat  62  so that the flow may be received by channel  70  passing radially between ribs  60  and providing a passageway into lower channel  50 . 
         [0060]    Referring now to  FIG. 11  improved flushing, for example, of blood drawn in the aspiration mode of  FIG. 9 , may be provided through the use of the diverter wall  72 , similar to diverter wall  53  of  FIG. 6  but passing along axis  30  and serving to direct flow in an opposite direction of the flow received by upper channel  48  toward the interface between the inner periphery of opening  56  and the valve seat  64 . Diverter wall  72  may be molded integrally with the housing  42  and also integrally molded with the valve seat  64 . Essentially, diverter wall  72  changes the channel  70  shown in  FIG. 10  to reverse flow direction just before it is received by lower channel  50 . 
         [0061]    Referring now to  FIG. 12 , in some embodiments, the elastomeric diaphragm  24  may be formed of two different elastomeric materials having different Shore hardnesses corresponding approximately to different elasticities of the materials. For example, the outer peripheral region  32  of the disk may be constructed of a relatively low hardness silicone elastomeric material whereas the central region  34  forming circular opening  56  may be constructed of a much harder silicone elastomeric material. The threshold opening pressures  47  and  49 , shown in  FIG. 7 , are defined by the geometry of the valve and by the elasticity of the elastomeric diaphragm  24  in the central region  34  and the outer peripheral region  32  and thus adjusting the elasticity of these materials can provide an additional dimension of adjustment and provide a greater difference in threshold opening pressures. For example, it is believed this design can provide a low threshold opening pressure  49  of less than 20 millibars and a very high threshold opening pressure  47  of greater than two bars or approximately 100 times greater than the threshold opening pressure  49 . 
         [0062]    In the embodiment of  FIG. 12 , the geometry of the elastomeric diaphragm  24  about the opening  56  is changed substantially from a planar configuration shown in  FIGS. 8-10  to provide a downwardly opening arch  80  whose inner leg forms a rim of opening  56 . Aspirated flow  82  past valve seat  84  must provide for substantially both a bending and substantial compression of components of the material of the elastomeric diaphragm  24  as a result of this art form. To this end, the upper portion of the arch  80  may be supported by ribs  58  extending downward from an upper wall of the cavity  28  that serve to brace the arch against axial movement along axis  30 . In this design, the valve seat  84  is substantially flat and a sharpened ridge  86  is formed on the lower surface of the periphery of opening  56  that seals against the flat surface of the valve seat  84 . 
         [0063]    Certain terminology is used herein for purposes of reference only, and thus is not intended to be limiting. For example, terms such as “upper”, “lower”, “above”, and “below” refer to directions in the drawings to which reference is made. Terms such as “front”, “back”, “rear”, “bottom” and “side”, describe the orientation of portions of the component within a consistent but arbitrary frame of reference which is made clear by reference to the text and the associated drawings describing the component under discussion. Such terminology may include the words specifically mentioned above, derivatives thereof, and words of similar import. Similarly, the terms “first”, “second” and other such numerical terms referring to structures do not imply a sequence or order unless clearly indicated by the context. 
         [0064]    When introducing elements or features of the present disclosure and the exemplary embodiments, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of such elements or features. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements or features other than those specifically noted. It is further to be understood that the method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed. 
         [0065]    Various features of the invention are set forth in the following claims. It should be understood that the invention is not limited in its application to the details of construction and arrangements of the components set forth herein. The invention is capable of other embodiments and of being practiced or carried out in various ways. Variations and modifications of the foregoing are within the scope of the present invention. It also being understood that the invention disclosed and defined herein extends to all alternative combinations of two or more of the individual features mentioned or evident from the text and/or drawings. All of these different combinations constitute various alternative aspects of the present invention. The embodiments described herein explain the best modes known for practicing the invention and will enable others skilled in the art to utilize the invention.