Abstract:
Fitting that is compatible with standard fittings is described. In one embodiment, the end of one of a matched set of fittings is provided with an elastomeric material. The elastomeric material deforms when the matched fittings are coupled, resulting in a reduced volume. In certain embodiments, a tube is provided through the tube which is attached at a proximal end and extends to the distal end of the elastomeric material. When the fitting are coupled the tube protrudes past the end of the elastomeric material and into the coupled fitting. In certain embodiments the fitting otherwise conforms to International Standard ISO 594.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 60/939,012, filed May 18, 2007, the entirety of which is incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention generally relates to fittings for connecting tubing, and more particularly to connectors that have small excess internal volumes. 
         [0004]    2. Discussion of the Background 
         [0005]    Medical and instrument tubing is typically joined by providing a connector that includes matching fittings on the ends of tubes to be joined. One common connector includes conical fittings. Conical fittings include a matched set of male and female fittings each having conical surfaces that, when the fittings are connected, provides leak-proof connections between tubes. Conical fittings that form a seal by forcing the fittings together are sometimes referred to as “slip fittings.” Conical fittings that also include threaded elements to secure the fittings are sometimes referred to as “lock fittings.” 
         [0006]    Standards have been developed to permit compatibility of standard fittings. An example of specifications for conical fittings used for medical applications may be found, for example, in the International Standard ISO 594 titled “Conical fittings with 6% (Luer) Taper for syringes, needles and certain other medical equipment,” and referred to herein as the “ISO Luer Standard.” Fittings meeting the ISO Luer Standard are referred to herein as “Luer fittings.” 
         [0007]    To facilitated an understanding of embodiments of the present invention,  FIGS. 1 through 3  are views of a prior art Luer slip fitting, where  FIG. 1  a side view of a male Luer fitting  10  and a matching female Luer fitting  20 , and  FIG. 2  is a sectional view  2 - 2  of the fittings. Male Luer fitting  10  has a distal end  12  for inserting into female Luer fitting  20  and a proximal end  14  for attaching to a tube (shown in  FIG. 3 ). Female Luer fitting  20  has a distal end  22  for accepting male Luer fitting  10  and a proximal end  24  for attaching to a tube (shown in  FIG. 3 ). Proximal ends  14  and  24  may each include, for example, a barb  13  to accept the end of a tube. 
         [0008]    The following discussion relates to fittings  10  and  20  that conform to the ISO Luer Standard. Fittings  10  and  20  each include surfaces having the shape of a conical frustum of a given slope, resulting in a conical angle θ, as shown. More specifically, male fitting  10  has an external frustoconical surface  11  with having a height A from a proximal base  17  to a distal top  16  having a diameter B. Female fitting  20  includes an internal frustoconical surface  21  that matches at least a portion of surface  11 . Specifically, surface  21  has a depth D extending from an opening at the distal base  27  with a diameter C to a proximal top  26 . The height A, diameters B and C and depth D, are mandated by the ISO Luer Standard, and define contacting surfaces. While the shape of contacting surfaces of surfaces  11  and  21  are particularly important for portions where the male and female fittings touch, the shape over other portions may have different conical angles or shapes, particularly at more proximal portions of the male and female fittings (compare, for example,  FIG. 1  with  FIGS. 4 and 5  of the first edition of the ISO Luer Standard). 
         [0009]    Neither the cross-sectional size nor cross-sectional shape of passageways  15  and  25  are specified in the ISO Luer Standards. For illustrative purposes, fittings  10  and  20  are shown having passageways  15  and  25 , respectively, that may each have approximately constant cross-sectional areas in a flow direction. Passageway  15  has a distal end  19  at top  16  and passageway  25  has a distal end  29  at top  26 . 
         [0010]    While standards, such as the ISO Luer Standard, provide a framework for producing interchangeable connectors, the volume and shape of the volume varies from fitting to fitting. This variation may present problems for low flow or low volume systems, or for systems requiring that the fluid within the connectors be exposed to only smooth surfaces. 
         [0011]      FIG. 3  is a sectional view  2 - 2  where fittings  10  and  20  are connected and a portion of surfaces  11  and  21  are in contact, where the portion is indicated by the length X. The ISO Luer Standard mandates that tops  16  and  26  be separated by a distance, which is indicated as distance between distal ends  19  and  29  as E=X−D. The value of E is not specified by the ISO Luer Standard, but is required to be greater than zero, resulting in a “dead space” within connected fittings  10  and  20 . The “dead space,” as used herein, refers to volume within coupled fittings  10  and  20  that is: 1) not within passageways  15  or  25 ; and 2) is not sealed off from passageways  15  or  25 . In other words, the dead space is any volume outside of the passageways leading into the coupled fittings into which fluid may migrate. Thus, for example, the dead space in the fittings of  FIG. 3  is a volume  300  that is between distal end  19  of passageway  15  and distal end  29  of passageway  25 . Because the distance E is non-zero, there is a finite volume V of dead space  300  within coupled fittings  10  and  20 . 
         [0012]    It is understood that, in some prior art embodiments, one or more of passageway  15  or  25  may terminate at top  16  or  26 , respectively, with a beveled or some other shaped surface, and thus the shape of the dead space may have some other shape. 
         [0013]    In the simplified illustration of  FIG. 3 , the frustoconical dead space  300  is approximately cylindrical, with a diameter of approximately B and height E, resulting in V=E*πB 2 /4. Since the value of E, as well as the cross-sectional diameter of passageways  15  and  25 , are not specified in the ISO Luer Standard, dead space volume V will not necessarily be the same from one fitting to another. For ISO Luer Standard compliant fittings, the minimum height E is approximately 1.75 mm and B is approximately 3.9 mm, for a volume V of approximately 21 μl. This calculation of V is approximate and for illustrative purposes, as there are no ISO Luer Standards for the internal size or shape of Luer fittings. 
         [0014]    The variation in dead space volume and shape from fitting-to-fitting within the ISO Luer Standard may present a problem for low volume or low flow systems. In addition, dead space is believed to be a problem in lines that are used to provide patients with medication. See, for example, the letter to the CANADIAN JOURNAL OF ANAESTHESIA, http://www.cja-jca.org/cgi/reprint/42/7/658.pdf). Thus, for example, if a line with such a connector is used to provide a patient with medication, some of the medication may remain trapped in the dead space. If the line is later flushed with saline, unknown and potentially dangerous amounts of the medication may be flushed from the dead space and infused into the patient. 
         [0015]    For all of these reasons there is need for connectors having predictable, and preferably low, internal volumes. 
       BRIEF SUMMARY OF THE INVENTION 
       [0016]    The present invention overcomes the limitations and problems of the prior art by providing a fitting that reduces the volume of standard fittings. 
         [0017]    In certain embodiments, a male fitting is provided. The male fitting extends longitudinally from proximal end to a distal end, and includes a first portion for mating with a matched female fitting; and a second portion having a length from the first portion to the distal end, where the length is greater than approximately 1.75 mm. 
         [0018]    In certain other embodiments, a male fitting is provided. The male fitting extends longitudinally from proximal end to a distal end, and includes a first portion for mating with a matched female fitting, and a second portion between the first portion and the distal end, where the second portion includes an elastomeric material. 
         [0019]    In certain embodiments, a male fitting conforming to International Standard ISO 594 is provided. The male fitting is connectable to a female fitting conforming to International Standard ISO 594. When the male fitting connected to the female fitting has a dead space, where the dead space has a volume of less than 15 μl. 
         [0020]    In certain embodiments, the dead space has a volume that is: less than 15 μl; less than 10 μl; less than 5 μl; less than 2 μl; less than 1 μl; or is approximately zero. 
         [0021]    In certain embodiment, the extension has a length of: approximately 1.75 mm; approximately 6 mm; greater than 1 mm; greater than 2 mm; greater than 3 mm; greater than 4 mm; greater than 5 mm; greater than 7 mm; greater than 8 mm; or greater than 9 mm. Alternatively, the extension have a length within the following ranges: between 1 mm and 10 mm; between 2 mm and 9 mm; between 3 mm and 8 mm; or between 4 mm and 7 mm. 
         [0022]    These features together with the various ancillary provisions and features which will become apparent to those skilled in the art from the following detailed description, are attained by the fitting of the present invention, preferred embodiments thereof being shown with reference to the accompanying drawings, by way of example only, wherein: 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         [0023]      FIG. 1  a side view of a prior art male Luer slip and a matching female Luer fitting; 
           [0024]      FIG. 2  is a sectional view  2 - 2  of the prior art fittings of  FIG. 1 ; 
           [0025]      FIG. 3  is a sectional view  2 - 2  where fittings are fully connected; 
           [0026]      FIG. 4  is a sectional view of one embodiment of a male Luer fitting; 
           [0027]      FIG. 5  is a sectional view of the male Luer fitting of  FIG. 4  mated with a female Luer fitting; 
           [0028]      FIG. 6  is a perspective view of an embodiment of a male Luer lock connector and a matching female Luer lock connector; 
           [0029]      FIG. 7  is a perspective view of the male Luer fitting of  FIG. 6 ; 
           [0030]      FIG. 8  is a sectional view  8 - 8  and  FIG. 9  is a sectional view  9 - 9  of the male Luer fitting of  FIG. 6 ; 
           [0031]      FIG. 10  is a sectional view  8 - 8  of the fitting of  FIG. 8  as attached to a tube; 
           [0032]      FIG. 11  is a detailed sectional view  11 - 11  of the female Luer connector of  FIG. 6 ; 
           [0033]      FIG. 12  is a sectional view  8 - 8  and  11 - 11  showing the male fitting and female fitting of  FIG. 6  connected; and 
           [0034]      FIG. 13  is a detailed sectional view  13 - 13  of  FIG. 12 . 
       
    
    
       [0035]    Reference symbols are used in the Figures to indicate certain components, aspects or features shown therein, with reference symbols common to more than one Figure indicating like components, aspects or features shown therein. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0036]    Embodiments will now be described with reference to Figures of conical Luer fittings. It is understood that the features described herein may be used in other fittings to reduce or otherwise modify the internal volume of connectors, as described herein. In certain embodiments, the coupled fitting presents a nearly uniform flow diameter for fluids within the fitting. 
         [0037]      FIG. 4  is a sectional view of one embodiment of a male Luer fitting  400 , which may be generally similar to fitting  10 , except as further detailed below. 
         [0038]    In one embodiment, fitting  400  includes a fitting  10  and also includes an extension  410  at distal end  12 . Extension  410  has a passageway  411  and an outer surface  415 , and that protrudes away from fitting  10  by a distance F away from top  16  to a distal surface  413 . In one embodiment, fitting  10  includes a rigid or semi-rigid material. Thus, for example and without limitation, fitting  10  includes a metal or a plastic. Examples of plastics for fitting  10  include, but are not limited to, a rigid thermoplastic such as polycarbonate (PC) radiation stable PC, acrylonitrile butadiene styrene (ABS), poly(methyl methacrylate) (PMMA), polyvinyl chloride (PVC), or polypropylene (PP). In another embodiment, extension  410  includes a material that is rigid or semi rigid. In yet another embodiment, extension  410  includes a material that is more compliant that that of fitting  10 , and is preferably resiliently deformable. Examples of materials for extension  410  include, but are not limited to elastomeric materials, such as a thermoplastic elastomer (TPE). Alternate materials for the extension include thermoplastic urethane (TPU) or silicone. 
         [0039]    In one embodiment, fitting  400  includes a passageway  15  and extension  410  includes passageway  411  that can accept a tube  1 . Specifically, an accepted tube  1  passes through passageways  15  and  411 , with a tube end  3  flush with distal surface  413 . In one embodiment, glue is added to proximal location  5 , such that tube  1  is fixed to the proximal end of the fitting. Thus, if extension  410  is compressed tube end  3  will protrude distally beyond distal surface  413 . In another embodiment, tube end  3  is within one of passageways  15  or  411 . 
         [0040]      FIG. 5  is a sectional view of the fitting  400  coupled to female Luer fitting  20 . The coupled connectors are shown for illustrative purposes, and do not limit the scope of claims of fitting  400 . Extension  410 , when located within coupled fittings  400  and  20  may reduce the volume of the dead space in one or more of several ways. First, the presence of extension  410  within coupled fittings  400  and  20 , whether the extension is formed from an elastomeric, rigid, or semi-rigid material, reduces the volume of dead space from that of prior art fittings, as in  FIG. 3 . In one embodiment, extension  410  is sized and is of a material resilient enough to reduce or otherwise modify the volume of connectors comprising the range of sizes permitted under the ISO Luer standards. 
         [0041]    Second, extension  410  may seal against the inner surfaces of fitting  20 , such as surface  21  or top  26 , further reducing the volume into which fluid from passageways  15  or  16  may migrate. 
         [0042]    Third, tube  1  may protrude to or into fitting  20 . As shown in  FIGS. 4 and 5 , in one embodiment extension  410  includes an elastomeric material and the distance F is equal to or greater than the distance E—that is, extension  410  is longer than the length of dead space  300  of the prior art fittings of  FIGS. 1-3 . When fitting  400  is used in place of fitting  10 , for example, extension  410  is compressed from a length F (as in  FIG. 4 ) to a length E, and tube end  3  extends to passageway  25  of female Luer fitting  20 , reducing the dead volume to essentially zero. In addition to greatly reducing or eliminating dead space, the smooth transition of flow diameters results in smoother flow through the coupled fittings  400  and  20 . 
         [0043]    In one embodiment, the dead volume in coupled fittings  400  and  20  is less than 20 μl. In alternative embodiments, the dead volume in coupled fittings  400  and  20  is less than 15 μl, is less than 10 μl, is less than 5 μl, is less than 2 μl, or is less than 1 μl. In another alternative embodiment, the dead volume in coupled fittings  400  and  20  is approximately zero. 
         [0044]      FIG. 6  is a perspective view of an embodiment of a male Luer lock connector  610  and a matching female Luer connector  620 , which may be generally similar to fittings  400  and  20 , except as further detailed below. 
         [0045]    Connector  610  is a lock fitting that includes a male Luer fitting  611  having a distal end  12 , and a surrounding lock element  615  having internal threads  617  and features  619  to facilitate handling the fitting. As described subsequently, fitting  610  is connectable to a tube. 
         [0046]    Connector  620  is a matching lock fitting for connector  610 . Connector  620  has a female Luer fitting  621  having an opening  622  to accept distal end  12 , and external threads  627  and features  629  for facilitating handling the fitting. Threads  617  and  627  are matching threads. Connector  620  also includes a tube  623  or an element or mechanism to permit the attaching of a tube to coupling end  621 . In one embodiment, fitting  621  is a prior art fitting  20 . 
         [0047]    In one embodiment, Connector  620  includes a standard locking conical fitting that conforms to a standard which may be, for example, the ISO Luer Standard. In another embodiment, connector  610  conforms to a conical fitting standard for a locking fitting, that is, it can mate with any female fitting conforming to the same standard, and also includes features and/or elements that reduce or otherwise modify the volume internal to connected fittings  610  and  620 . 
         [0048]      FIG. 7  is a perspective view of fitting  611 —that is, connector  620  with lock element  615  removed, Fitting  611  includes an extension  701  at a distal location having a distal end  723 , a frustoconical portion  703  including a surface  711 , and a proximal portion  705 . Surface  711  may be generally similar to surface  11 —that is, it may mate with a matching internal frustoconical surface of a female fitting. Extension  701  may be generally similar to extension  410  in that it extends laterally beyond the distal end of frustoconical portion  703 . 
         [0049]    Fitting  611  is shown in greater detail in  FIG. 8 , which is a longitudinal sectional view  8 - 8  of  FIG. 7  and in  FIG. 9 , which is an orthogonal longitudinal section view  9 - 9  of  FIG. 7 . As shown in  FIGS. 8 and 9 , fitting  611  has a passageway  715  and may be formed from a first material  710  and a second material  720 . Material  710  is structural and includes the majority of fitting  611 . Thus, for example, material  710  includes proximal end  613  and at least part of frustoconical portion  703 . In one embodiment, material  710  is a MAKROLON® RX2530-1118 Polycarbonate (Bayer MaterialScience, Leverkusen, Germany). 
         [0050]    Material  720  may form most of extension  710  and has a portion  803  that protrudes under surface  711  and forms at least part of proximal portion  705 . As shown in  FIG. 8 , an annulus  801  of material  720  is connected via two radial portions  901  to extension  701 . In one embodiment. Annulus  801  functions as an anchor for extension  710  so that the extension is not easily pulled from fitting  611 . Material  720  may be, for example and without limitation, the material of extension  410 . In one embodiment, the first material extension  720  is a G2706 TPE (GSL) (Kraton Polymers, Houston, Tex.). In one embodiment the longitudinal extent of extension  710  is approximately 6 mm. In alternative embodiments, the longitudinal extent of extension  710  is greater than 1 mm, is approximately 1.75 mm, is greater than approximately 1.75 mm, is greater than 2 mm, is greater than 3 mm, is greater than 4 mm, is greater than 5 mm, is greater than 7 mm, is greater than 8 mm, or is greater than 9 mm. In yet other embodiments, the longitudinal extent of extension  710  is between 1 mm and 10 mm, is between 2 mm and 9 mm, is between 3 mm and 8 mm, or is between 4 mm and 7 mm. 
         [0051]      FIG. 10  is a sectional view  8 - 8  of the male Luer lock fitting  611  having a tube  1 . Fitting  611  and tube  1  are generally similar to fitting  400  and tube  1  of  FIGS. 4 and 5 , except as further detailed below. 
         [0052]    In one embodiment, tube  1  is a PVC tube. In another embodiment, tube  1  is a co-extruded tubing having a polyethylene “sleeve” inside a PVC outer tube. As shown in  FIG. 10 , fitting  611  is attached to tube  1  with end  3  that is approximately even with distal end  723 . 
         [0053]    In one embodiment, tube  1  is a small bore tube. Thus in one example, which is not meant to limit the scope of the present invention, the outer diameter of tube  1  is slightly less than the diameter of passageway  715 . In one embodiment, the outer diameter of tube  1  is 0.060 inches and the inner diameter of the tube is 0.030 inches. In one embodiment, the outer surface of tube  1  and an inner surface of proximal end  613  are affixed at location  5  using glue, such as a UV cured glue. 
         [0054]    Extension  701  includes an outer surface  721  having ridges. This shape provides space for extension  701  to compress into when joined with a mating fitting, as in  FIG. 12 and 13 , below. Alternatively, outer surface  721  may form a fluid-tight seal against fitting  620 . 
         [0055]    In one embodiment, fitting  611  is formed by injection molding material  710 , which includes radial portions  901  and annulus  801 . Material  720  is then overmolded or co-molded over material  710  to form extension  720  and fill in annulus  801 , and radial portion  910 . Tube end  3  is then inserted through proximal end  613  to distal end  723 , with glue being applied location  5 . 
         [0056]      FIG. 11  is a sectional view  11 - 11  of the female Luer fitting  620  of  FIG. 6 . Fitting  620  includes a body  621  having an inner surface  1102  including a frustoconical surface  1110 , an extension portion  1120 , and an inner surface  1105  along a portion of the body. Portion  110  may be, for example and without limitation, a conical frustum portion compliant with the ISO Luer Standard for a female fitting, and may be a mating surface to surface  711 . 
         [0057]      FIG. 12  is a sectional view of coupled fittings  611  and  620 , that is, when surfaces  702  and  1110  are in contact, and  FIG. 13  is a detailed sectional view  13 - 13  of  FIG. 12 . 
         [0058]    As shown in  FIG. 12 , extension  701  is forced by extension portion  1120  into a compressed configuration. Thus, for example, extension  701  may compress by up to one half its undeformed length. Since tube  1  is affixed to proximal end  613  at location  5 , the distal end  3  of the tube extends beyond distal end  723  of extension  701 . In one embodiment, tube end  3  extends to the most proximal end of portion  820 . As a result, flow within tube  1  makes a smooth transition as it flows through fittings  610  and  620 . 
         [0059]    Also shown in  FIG. 13  are details of an embodiment where extension  701  seats on the surface of extension portion  1120 . Specifically, ridges of outer surface  721  are forced on to the surface of extension portion  1120  to form a fluid-tight seal, as indicated at a sealing location  1301 . The seal prevents fluid from moving into the fitting. Thus, for example, there is a void  1303  between the surface and inner surface  1120  that is sealed at sealing location  1301 , preventing fluid from moving from tube  1  into the void. The seal at sealing location  1301  thus prevents void  1301  from being included as part of the dead space of coupled fittings  611  and  620 . 
         [0060]    Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to one of ordinary skill in the art from this disclosure, in one or more embodiments. 
         [0061]    Similarly, it should be appreciated that in the above description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. 
         [0062]    In summary, embodiments of fittings include several features, some or all of which may be present in any specific embodiment. In general, fittings of the present invention include one or more of the following elements: 1) an extension to a standard fitting, where the material of the extension may or may not be an elastomeric material; and/or 2) a tube extending through a standard fitting, where the tube may or may not extend to the distal end of the fitting. While embodiments of fittings are shown in various configurations relative to the coupled fitting, the present invention is not limited to specific details of how the fitting coupled to the other fitting, except as explicitly claimed. Thus, for example, in various embodiments, the claimed fitting of the coupled fittings includes a standard fitting with 1) an extension that is or is not compressed; 2) a tube having a distal end that terminates before, at, or within the coupled fitting. 
         [0063]    Thus, the claims following the Detailed Description are hereby expressly incorporated into this Detailed Description, with each claim standing on its own as a separate embodiment of this invention.