Abstract:
A medical stopcock is provided that is constructed and arranged to withstand high pressures and gamma irradiation. The stopcock generally includes a housing and a valve member. The valve member is trapped within the housing so that, when subjected to relatively high pressures, the valve member is unlikely to become separated from the housing. A handle member is attached to the valve member and allows the valve member to be rotated from open to closed positions. In some preferred embodiments, the handle member locks the valve member within the housing, when attached. All of the components are constructed of gamma-stable materials so that the stopcock may be sterilized, in its package, using gamma irradiation.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The device of the present invention pertains to a stopcock capable of withstanding gamma radiation. The stopcock is constructed and arranged for high pressure applications.  
           [0002]    Gamma radiation is a form of energy capable of deep penetration. Gamma irradiation is the use of gamma radiation to sterilize medical devices. Gamma radiation kills microorganisms throughout a product and its packaging with very little heating. As a sterilant, gamma radiation is thorough; no area of the product, its components, or packaging is left with uncertain sterility after treatment. Furthermore, gamma irradiation leaves no residue.  
           [0003]    Traditional sterilization techniques include batch sterilization using ethylene oxide (EtO). EtO sterilization leaves a residue and requires an aeration period prior to shipment. The packaging must be gas permeable to allow the EtO to completely evaporate prior to use. Gas permeable packaging, however, increases the possibility of contamination over time. Thus, a relatively early expiration date is assigned to the sterilized device. Gamma radiation, on the other hand, penetrates through the packaging and, again, leaves no residue.  
           [0004]    Commercially-available stopcocks, however, are constructed of materials that are not dimensionally stable when exposed to gamma radiation. Gamma-stable materials are more expensive and more rigid than the softer materials used to form the valve members of the commercially-available stopcocks. FIG. 1 shows a cross-sectional view of a typical, commercially-available stopcock  1 . The stopcock  1  includes a valve member  3  inserted into a housing  5 . The valve member  3  may be hollow, as shown, or solid and includes a port  7  that can be aligned with passage  9  of the housing  5 .  
           [0005]    The two-piece construction of the stopcock  1  relies on an interference fit between the valve member  3  and the housing  5 . In other words, the valve member  3  is slightly larger than the interior of the housing  5 . When the valve member  3  is inserted into the housing  5 , it compresses and forms a fluid-tight fit. Thus, the valve member  3  must be constructed of a softer plastic than that of the housing  5 . Typical materials used to make these valve members  3  include acetal and acrylonitrile butadiene-styrene (ABS).  
           [0006]    Unfortunately, these soft materials used to make the valve members  3  cannot withstand gamma irradiation. When exposed, the valve members  3  change dimension and render the stopcock unusable. Thus, a less effective, more expensive, form of sterilization must be used.  
           [0007]    Another disadvantage of these stopcocks  1  pertains to the design of the snap fit between the soft valve member  3  and the housing  5 . As seen in FIG. 1, the snap fit arrangement is achieved by providing an angled flange  11  at the lower end of the valve member  3  that is configured to mate with a corresponding inwardly-projecting flange  13  that is integral with the housing  5 . To allow assembly and a fluid tight fit, the flanges  11  and  13  have to be relatively small so that the flange  11  on the valve member  3  may deform and reform as it passes over the other flange  13  during assembly. The size relationship between the two flanges  11  and  13  limits the use of these stopcocks  1  for high pressure applications. When subjected to high pressures, there is a tendency for the valve members  3  to be ejected from the housing  5 .  
           [0008]    A further disadvantage of these stopcocks  1  is that they require excessive turning force to open and close the valves. Because the fluid-tight integrity depends on the friction fit between valve member  3  and the housing  5 , and thus the valve member  3  is slightly larger than the housing  5 , it is difficult to turn the valve member  3  within the housing  5 . Users complain that two hands are necessary to operate the stopcocks  1  without causing the tubing attached to the stopcocks from becoming twisted or dislodged. Further, the relatively small size of the stopcocks  1  make it difficult to grasp the housing  5 , to turn the valve member  3 , without having fingers interfere with the handle of the valve member  3 . This problem is especially prevalent when turning the valve members  3  of high pressure stopcocks while wearing wet rubber gloves.  
           [0009]    Additionally, materials like acetal and ABS are opaque, which is yet another disadvantage. For purposes of blood and bubble detection, it is preferable to use a fluid network comprised entirely of clear components.  
           [0010]    There is thus a need for a stopcock that can withstand gamma irradiation.  
           [0011]    There is a further need for a stopcock that is constructed and arranged to withstand high pressures.  
           [0012]    There is also a need for a stopcock that can be opened and closed with relative ease.  
           [0013]    There is an additional need for a stopcock that is constructed entirely of clear materials.  
         BRIEF SUMMARY OF THE INVENTION  
         [0014]    The present invention pertains to a stopcock made entirely of materials capable of withstanding sterilization using gamma irradiation. A method of making a stopcock is disclosed that allows a stopcock housing to be formed around the outside of a valve member, thereby providing an improved fit between the valve member and the housing.  
           [0015]    The internal valve member is constructed of a rigid material, such as polyetheretherketone (PEEK), capable of withstanding gamma rays without experiencing a change in dimension. The external housing is also constructed of such a material, usually polycarbonate. The housing includes a cylindrical interior cavity with an inner diameter approximately equal to the outer diameter of the valve member. The valve member has a stop, preferably a flange, extending radially from one end to prevent the valve member from passing completely through the housing. The valve member is secured at the other end by attaching a handle member thereto. The attachment is made with an adhesive, snap fit, friction fit, weld (e.g. ultrasonic), pin connection, or the like.  
           [0016]    PEEK is just an example of many materials acceptable for use in making the stopcock of the present invention. Other example materials include polyesters, glycol modified polyethylene terepthalate (PETG), polycarbonate, polycarbonate alloys, polysulfone, polyurethane, polyetherketoneketone (PEKK), polyetherimide, thermosets, polyamides, polyaryletherketone (PAEK), and flouroplastics other than polytetrafluoroethylene (PTFE) and fluorinated ethylene propylene (FEP). Examples of acceptable thermosets include polyimides, polyurethanes, and polyesters.  
           [0017]    The handle member, valve member and housing all may be made of the same material. However, using materials having slightly different melting points for the housing and the valve member provides an advantageous manufacturing option. If the housing is made of a material with a slightly lower melting point than that of the valve member, the housing may be formed by over molding the valve member. This ensures that the interior cavity of the housing exactly matches the size of the valve member. The difference in melting temperature prevents the housing material from fusing with the valve member.  
           [0018]    Alternatively, the process of over-molding may use materials that are not considered gamma-stable as a way of ensuring a close fit between the outer housing and the inner valve member. If the inner valve member and the outer housing are made of materials that react differently when exposed to gamma radiation, the outer housing may be made to shrink around the inner valve member during gamma irradiation. This concept not only creates a water-tight fit between the housing and the valve member, it permits the use of less expensive, non-gamma-stable materials.  
           [0019]    Additionally, considering the high cost of gamma-stable materials, it may be desired to provide a non-gamma-stable handle, attachable to a gamma-stable valve member. Doing so would not only provide a cost benefit, especially in the case of large stopcocks, it would also allow design flexibility. For example, it may be desired to provide a variety of handle members having different colors. The colors could then be selected to identify the type of fluid travelling through the stopcock. The valve member may also be designed without a handle, for use with an automatic device constructed and arranged to operate the stopcock.  
           [0020]    Further, to provide turning ease, a grip is preferably incorporated into the stopcock housing which can be used to hold the housing while turning the valve member, thereby giving the physician greater turning leverage. The grip may be an axial extension of the housing or may extend radially in a direction where interference with ports is not created.  
           [0021]    One aspect of the present invention provides a stopcock having a valve member that is attachable to, or integral with, handle members on either side of the stopcock. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0022]    [0022]FIG. 1 is a prior art stopcock;  
         [0023]    [0023]FIG. 2 is a perspective view of a preferred embodiment of the stopcock of the present invention with the handle member separated from the valve member and the housing partially cut away;  
         [0024]    [0024]FIG. 2A is a perspective sectional view of an alternative embodiment of a stopcock of the present invention with the handle member separated from the valve member;  
         [0025]    [0025]FIG. 3 is a perspective view of a stopcock housing of the present invention;  
         [0026]    [0026]FIG. 4 is a perspective view of a valve member of the present invention;  
         [0027]    [0027]FIG. 5 is a cutaway elevation of another preferred embodiment of the stopcock of the present invention;  
         [0028]    [0028]FIG. 6 is a partial perspective view of an embodiment of the second end of the housing of the present invention;  
         [0029]    [0029]FIG. 7 is a cutaway elevation of yet another preferred embodiment of the stopcock of the present invention;  
         [0030]    [0030]FIG. 8 is a perspective view of a preferred embodiment of a stopcock of the present invention, and;  
         [0031]    [0031]FIG. 9 is a perspective view of another preferred embodiment of a stopcock of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0032]    Referring now to FIG. 2, there is shown a stopcock  10  of the present invention. The stopcock  10  generally comprises a housing  12 , a valve member  14 , and a handle member  16 . The housing  12 , the valve member  14  and the handle member  16  are all preferably made of materials that remain dimensionally stable when exposed to gamma radiation.  
         [0033]    The housing  12  is best shown in FIG. 3 and includes at least one inlet port  18  and at least one outlet port  20 . Both ports  18  and  20  lead into an interior cavity  22  sized to receive the valve member  14 . Notably, the housing  12  is open at a first end  24  and a second end  26 , defining the limits of the interior cavity  22 . The importance of these open ends  24  and  26  is discussed below.  
         [0034]    [0034]FIG. 4 shows a valve member  14 . The valve member  14  generally comprises a cylinder sized to be rotatably contained within the interior cavity  22 . The valve member  14  includes a first end  28  and a second end  30  that correspond to the first and second ends  24  and  26  of the housing  12  when assembled. The second end  30  of the valve member  14  includes a stop  32  preferably in the form of a flange. The stop  32  is sized to interfere with the opening at the second end  26  of the housing  12 . The stop  32  thus prevents the valve member  14  from being removed from the housing  12  through the first end  24  of the housing  12 . The valve member  14  further includes a passage  34  that is alignable with the ports  18  and  20  of the housing  12  when it is desired to establish fluid communication between the ports  18  and  20 . Additionally, at the first end  28  of the valve member  14 , there is an attachment area  36 , usable to attach the valve member  14  to the handle member  16 .  
         [0035]    The handle member  16  is shown in FIG. 2 and includes an attachment area  38  that is configured to mate with the attachment area  36  of the valve member  14 . The attachment areas  36  and  38  are shown in FIGS. 2 and 4 as being square female and male couplings, respectively. One skilled in the art will understand that many configurations would perform the desired function of attaching the handle member  16  to the valve member  14 . The male and female coupling arrangement shown in the Figures serves to provide adequate surface area for the application of adhesive, if desired, and also provides sufficient structural interaction between the valve member  14  and the handle member  16  to allow the handle member  16  to be used to twist the valve member  14 . The handle member  16  further includes a contact surface  40 . When the handle member  16  is attached to the valve member  14 , the contact surface  40  acts against the first end  24  of the housing  12 . The contact surface  40  and the stop  32  together prevent the valve member  14  from moving axially, relative to the housing  12 . Thus the valve member  14  is axially locked within the housing  12 , yet still allowed to rotate.  
         [0036]    [0036]FIG. 2A shows an alternative preferred configuration for attaching the handle member  16  to the valve member  14 . Handle member  16  includes a slot  17  configured to mate with a valve member extension  19 . Preferably the valve member extension  19  forms a snap lock fit with the slot  17 . When the handle member  16  is snapped onto the valve member  14 , the underside of the handle member  16  forms the contact surface  40 , which acts against the first end  24  of the housing  12  to prevent the valve member  14  from becoming disengaged from the housing  12 .  
         [0037]    The materials used to make the housing  12 , the valve member  14 , and the handle member  16 , are preferably clear and gamma-stable, and thus allow the entire valve to be assembled and packaged prior to sterilization using gamma irradiation. Depending on the manufacturing method chosen to make the valve  10 , discussed below, the materials used in the housing  12 , the valve member  14 , and the handle member  16  may be the same or different. For example, to reduce costs, the handle member may be made out of less expensive, non-gamma-stable materials. Acetal and ABS provide two examples of acceptable materials.  
         [0038]    Gamma-stable materials, acceptable for use in making the valve  10  of the present invention include PEEK, polyesters, PETG, polycarbonate, polycarbonate alloys, polysulfone, polyurethane, PEKK, polyetherimide, thermosets, polyamides, PAEK, and flouroplastics other than PTFE and FEP. Examples of acceptable thermosets include polyimides, polyurethanes, and polyesters. These materials are provided by way of example and are not intended to represent an exclusive list of acceptable materials. Any gamma-stable material exhibiting sufficient structural integrity is acceptable.  
         [0039]    Once materials are selected and used to form the housing  12 , valve member  14  and handle member  16 , the valve  10  is assembled by introducing the first end  28  of the valve member  14  into the second end  26  of the housing  12 . The valve member  14  slides into the interior cavity  22  of the housing  12  until the stop  32  abuts against the second end  26  of the housing  12 . Next the handle member  16  is attached to the valve member  14  by aligning the respective attachment areas  36  and  38  with each other, and securing them together using a gamma-stable adhesive, ultrasonic weld, mechanical connection, or the like.  
         [0040]    Various embodiments of the present invention provide a stopcock  10  whereby the handle member  16  and the valve member  14  are integral. One such embodiment is shown in FIG. 5. The valve member  14  defines a hole  42  at its second end  30  through which a pin  44  is placed after the valve member  14  is inserted into the housing  12 . A stop (not shown) may be provided to act against the first end  24  of the housing  12 , such as stop  40  shown in FIG. 2. Alternatively, as shown in FIG. 5, the valve member  14  and the interior cavity  22  are slightly conical, obviating the need for a stop  40 , and better ensuring a seal is formed between the valve member  14  and the housing  12 . The hole  42  is placed to create a slight downward force on the valve member  14  when the pin  44  is in place.  
         [0041]    [0041]FIG. 6 shows an embodiment of a housing  12  that is shaped to increase the downward force on the valve member  14 . The second end  26  of the housing  12  is shaped to form a recessed area  46  that provides adequate clearance to place the pin  44  through the hole  42  in the valve member  14 , when the hole  42  is aligned with the recessed area  46 .  
         [0042]    Adjacent to the recessed area  46  is an angled ramp surface  48 . Once the pin  44  is in place, the valve member  14  is rotated so that the pin  44  meets with increasing resistance by the ramp surface  48 , as the valve member  14  is pulled deeper into the interior cavity  22 . If the valve member  14  and interior cavity  22  are conical, this ramp effect creates a greater seal between the side wall of the valve member  14  and the inner side wall of the housing  12  defining the interior cavity  22 . If a cylindrical valve member  14  and interior cavity  22  are used, along with a stop  40  such as that shown in FIG. 2, the ramp effect creates a tighter seal between the stop  40  and the first end  24  of the housing  12 .  
         [0043]    At the end of the angled ramp surface  48  is a catch  50 . Once the valve member  14  is rotated sufficiently, the pin  44  will overcome the ramp  48  and snap behind the catch  50 . The catch  50  prevents counter rotation of the valve member  14  to the extent that the pin  44  reenters the recessed area  46  and becomes dislodged. The catch  50  thus defines a rotational limit on the valve member  14 .  
         [0044]    Adjacent the catch  50  is an operating surface  52 . This surface  52  is relatively parallel to the plane the pin  44  defines as the valve member  14  is rotated. Preferably, the operating surface  52  also includes level portions  53  and tightening portions  55 . The level portions  53  are positioned to provide a minimal amount of downward force on the pin  44  so the valve member  14  may be rotated with ease. The tightening portions  55  are positioned to correspond with alignment positions between the valve member passage  34  and the housing ports  18  and  20 . Thus, when the valve member  14  is in alignment with the ports of the housing  12 , the valve member  14  is pulled into tight contact with the interior walls of the housing  12 , thereby creating a fluid-tight seal acceptable for high pressure operation. A notch  57  may be included to provide a tactile feedback to the operator as to when the valve member  14  is in alignment with the housing ports  18  and  20 . The angular operating range of the valve member  14  is defined at one extreme by the catch  50 , as discussed above, and is defined at an opposite extreme by a rotational stop  54 . The rotational stop  54  prevents the pin  44  from rotating to the point where it enters the recessed area  46  on the opposite side of the housing  12 , designed to accommodate the other end of the pin  44 .  
         [0045]    One manufacturing method of the present invention allows the use of a valve member  14 , which is integral with a handle member  12 , and does not require the use of a pin  44 . FIG. 7 shows an embodiment of stopcock  10  whereby the valve member  14  and the interior cavity  22  of the housing  12  are curved such that the first end  24  and the second end  26  of the housing  12  are narrower than the other parts of the housing  12 . Thus, the valve member  14  is locked inside the housing  12 .  
         [0046]    To manufacture the stopcock  10  of FIG. 7, the valve member  14  is molded of a first gamma-stable material. A rod (not shown) is then placed through the passage  34  to keep the passage  34  open during the remainder of the manufacturing process and to form the inlet port  18  and outlet port  20  of the housing  12 . The housing  12  is then cast around the valve member  14  and rod using a second gamma-stable material that has a lower melting temperature than that of the first gamma-stable material. Using materials with different melting points and different molding temperatures ensures that the valve member  14  won&#39;t melt and adhere to the housing  12 . A light agent, such as a lubricant, may be applied to the valve member  14  to further prevent the housing  12  from adhering thereto. For example, PEEK may be used as a first material to make the valve body  14 . Polycarbonate could then be used as the second material to mold the housing  12 . Polycarbonate has a melting temperature of about 540-575° F. but a relatively low molding temperature of about 150-220° F.  
         [0047]    Once the housing  12  has solidified, the rod is removed and the valve member  14  may be rotated within the housing  12 . An alternative to casting the housing  12  around the valve member  14  is a dip coating process whereby the valve member  14  and rod are repeatedly dipped into a liquid volume of the second material to form the housing  12 .  
         [0048]    [0048]FIG. 8 is a preferred embodiment of the stopcock  10  of the present invention. The stopcock  10  is shown as a three-way stopcock with one inlet port  18  and two outlet ports  20 . A flange  60  is integral with the ports  18  and  20  and extends therefrom. The flange  60  may be a different material than the rest of the housing  12  but is preferably the same material. The flange  60  adds rigidity to the housing  12  for high pressure operations and also provides an area  62  to grip the valve  10  while turning the handle member  16 . Gripping the flange  60  provides increasing turning power and prevents fingers from interfering with the movement of the handle member  16 .  
         [0049]    [0049]FIG. 9 is another preferred embodiment of the stopcock  10  of the present invention. The stopcock  10  is shown as a three-way stopcock with one inlet port  18  and two outlet ports  20 . A grip  64  extends from the housing  12  at an angle that does not interfere with the range of motion of the handle member  16 , the various positions of which are shown in phantom lines. Like the flange  60  shown in FIG. 8, using the grip  64  increases turning power and prevents fingers from interfering with the movement of the handle member  16 .  
         [0050]    The foregoing description addresses embodiments encompassing the principles of the present invention. The embodiments may be changed, modified and/or implemented using various types of arrangements. For example, the stopcock of the present invention has been herein described as pertaining to medical applications. However, it is envisioned, and would be clear to one skilled in the art, that the teachings of the present invention could be applied to applications in fields such as electronics, microbiology, or others requiring sterility. Thus, those skilled in the art will readily recognize various modifications and changes that may be made to the invention without strictly following the exemplary embodiments and applications illustrated and described herein, and without departing from the scope of the invention, which is set forth in the following claims.