Patent Publication Number: US-2007112332-A1

Title: Medical access device

Description:
BACKGROUND OF THE INVENTION  
      The present invention relates to a connector for accessing patient fluid lines. In particular, the present invention is an access connector that may be opened by a tubular portion of a medical device, such as a male luer taper of a syringe.  
      In the course of treating patients, clinicians are continually transferring patient fluids between various containers and intravascular (IV) lines or through IV catheters. Transfer of these fluids is preferably through a closed system to prevent microbes from entering the system and causing infections in the patients. Many of these closed systems have relied on the use of a needle to penetrate a rubber or silicone septum to gain access to the fluid lines. The clinician may then inject fluid into or withdraw fluid from the patient via a needle and syringe. The septum reseals after the needle is withdrawn, which prevents backflow of the fluids and closes the system once again.  
      Because of the concern over accidental puncture with needles contaminated with a patient&#39;s blood or other fluids, needleless mechanisms have been developed to access patient fluid lines. One such mechanism utilizes a silicone septum that has a slit in it wide enough to allow a standard male luer taper to access the fluids. In this type of mechanism, the silicone septum is encompassed by a thermoplastic housing. With current connectors, the septum is bonded to the housing with adhesive.  
      Consistent bonding is needed to prevent the septum from rotating within the housing while a male luer-lock taper is locked and unlocked from the connector. In addition, as a male luer taper is drawn out of the septum, the taper tends to stick to the septum and stretches the septum out of the housing. If the septum is not properly bonded to the housing, the septum will pull out, or, as the taper slips off the septum, the septum snaps back into the housing causing fluids to spatter.  
     BRIEF SUMMARY OF THE INVENTION  
      The present invention is an access connector for accessing patient fluid lines. The housing of the connector includes a body and base. A frame is integrally molded to a septum, and the frame is then attached to the top end of the housing. The septum provides a resealable access to the fluid line. The present invention minimizes axial and rotational movement between the housing and the septum to allow optimum performance by the connector. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1A  is a perspective view of a representative embodiment of a first access connector.  
       FIG. 1B  is an exploded view of the first access connector.  
       FIG. 1C  is a cross-sectional view of the septum, ring and housing of the first access connector.  
       FIG. 2A  is a perspective view of the ring of a second access connector.  
       FIG. 2B  is a is a perspective view of the integrally molded ring and septum of the second access connector.  
       FIG. 2C  is a cross-sectional view of the septum, ring and housing of the second access connector.  
       FIG. 2D  is a perspective view of a representative embodiment of the second access connector.  
       FIG. 3A  is a perspective view of the segment of a second access connector.  
       FIG. 3B  is a cross-sectional view of the septum, segments and housing of the third access connector.  
       FIG. 3C  is a perspective view of a representative embodiment of the third access connector.  
       FIG. 4A  is a perspective view of the segment of the fourth access connector.  
       FIG. 4B  is a cross-sectional view of the septum, segments and housing of the fourth access connector.  
       FIG. 4C  is a perspective view of a representative embodiment of the fourth access connector.  
       FIG. 5  is a perspective view of a representative embodiment of fifth access connector.  
       FIGS. 6 and 7  are side views showing a method of deforming a septum assembly.  
       FIG. 8  is a side view of a deformed septum assembly. 
    
    
     DETAILED DESCRIPTION  
       FIGS. 1A-1C  show components of a representative embodiment of access connector  10   a , which housing  12  and septum assembly  14 . Housing  12  includes body  16  with tower  18  and thread  20 , base  22  and fluid line port  24 . Septum assembly  14  includes septum  26  with slit  28  and frame  30 .  
      Housing  12  and frame  30  are typically made of thermoplastic material such as polycarbonate, polyesters and polycarbonate/polyester blends. Septum  26  can be made from silicone or polyisoprene. A suitable material is adhesive grade liquid silicone rubber. Housing  12 , frame  30  and septum  26  may be fabricated from other materials as long as septum  26  is flexible, while housing  12  and frame  30  are relatively rigid.  
      Frame  30  in  FIGS. 1A-1C  is a thermoplastic ring that surrounds the top of septum  26 . Septum assembly  14  is integrally formed by an injection molding process such as insert molding or multi-shot molding. As a result, septum  26  and frame  30  are bonded together as a part of the molding process.  
      Tower  18  and body  16  are fabricated as a single piece, typically by injection molding. Frame  30  is attached or bonded to the top end of tower  18 . Base  22 , which also is typically formed by injection molding, is attached or bonded to the bottom of body  16 . Thread  20  extends around the external surface of tower  18 , and port  24  is at the bottom of base  22 .  
      In use, connector  10   a  is connected to a patient fluid line via port  24 . The patient fluid line may be any of a number of types such as IV lines, saline wells, arterial lines, hemodialysis lines, etc. When connected, the system remains closed to prevent entry of microbes that could cause infection and back flow of any fluids out of the system. The Q-Syte™ closed luer access device from Becton, Dickinson and Company is an example of a connector that may be assembled according to the present invention.  
      Connector  10   a  accepts a tubular portion of a medical device. For example, a medical device having a male luer taper, such as a syringe, is used to infuse or withdraw fluids from the patient fluid line via connector  10   a . The male luer taper is inserted into slit  28  of septum  26  and, if the medical device has a luer lock, rotated to interlock the medical device with connector  10   a  via thread  20 . Medical devices that utilize a luer slip can also be used with connector  10   a  by simply sliding the male luer taper in place. Less typically, connector  10   a  may be fabricated without thread  20 , but then connector  10   a  could only be used in combination with a luer slip and not a luer lock.  
      Once the male luer taper is in place, a clinician is then able to either infuse the patient fluid line or draw fluids from it. Medical devices having a luer lock are rotated in the opposite direction and pulled out for withdrawal from septum  28 , while medical devices having a luer slip are simply pulled out. Frame  30  is shaped to compress septum  26  such that slit  28  closes tightly. (This is discussed below in more detail.) The system remains closed, and the risk of entry by microbes or leakage of contaminated fluids is minimized. In addition, there is no threat of accidental needle sticks.  
      As described above, the male luer taper must be inserted into, withdrawn from and rotated within septum  26 , and connector  10   a  must be able to perform optimally after multiple insertions and withdrawals. Because septum  26  and frame  30  are bonded together, and frame  30  is bonded to housing  12 , axial and rotational movement of septum  26  relative to housing  12  is minimized. For instance, the integral bond between septum  26  and frame  30  minimizes snapback, which was previously discussed.  
      With current connectors, frame  30  and body  16  are fabricated as a single piece and then assembled with septum  26  and base  22  to form a connector. However, that configuration does not allow septum  26  to be molded directly into housing  12 .  
       FIG. 1B  is an exploded view of a representative embodiment of connector  10   a . In addition to the structures identified in  FIG. 1A ,  FIG. 1B  shows top disk  32 , column  33  and bottom disk  34  of septum  26 , rim  18   a  of tower  18 , bottom edge  16   a  of body  16  and wall  22   a , lip  22   b  and slot  22   c  of base  22 .  
      In the present invention, frame  30  and top disk  32  of septum  26  are attached during an injection molding process. The injection molding process is typically carried out in one of two ways, either by insert molding or multi-shot (e.g. two-shot) molding. This molding process involves two dissimilar materials that are being brought together into one molding operation.  
      For insert molding, the thermoplastic material used for frame  30  is rigid at room temperature and melted just prior to injecting under pressure into a mold. The thermoplastic material cools and solidifies taking the shape of the mold cavity. Once cooled, frame  30  is de-molded.  
      Frame  30  is then inserted into a mold cavity shaped for the formation of septum  26 . A two-component silicone is injected into the heated septum-shaped mold cavity under pressure. The two components, which are liquid at room temperature, contact the hot mold, and react and solidify taking the shape of the mold cavity, and the interface between frame  30  and top disk  32  fuse together. Septum assembly  14  is de-molded while still hot and allowed to cool outside of the mold.  
      Frame  30  may also be pretreated prior to the overmolding process to strengthen the bond. Some examples of pretreatment include passing over an open flame, exposing to ultraviolet light, exposing to plasma or electrical energy and coating with chemical primers.  
      For two-shot molding, molten thermoplastic material is injected under pressure into a ring-shaped mold cavity and allowed to at least partially solidify to form frame  30 . The mold system is then adjusted by exchanging one of the mold halves such that frame  30  is within and partially defines a septum-shaped mold cavity. Silicone, as described above, is then injected into the septum-shaped mold cavity and solidified. Septum assembly  14 , formed by the combination of frame  30  fused to septum  26  is de-molded from the septum-shaped mold cavity.  
      After septum assembly  14  has been formed by insert molding or two-shot molding, bottom disk  34  of septum  26  is collapsed and inserted through tower  18 . Bottom disk  34  opens up within body  16 , and frame  30  rests on rim  18   a . Frame  30  may be attached to tower  18  by any of a number of ways such as by ultrasonic welding, solvent bonding, adhesive bonding, etc. Frame  30  and tower  18  readily bond, because they are fabricated from the same or same class of materials.  
      As previously noted, frame  30  is a ring shaped such that it exerts a compressive force on septum  26  to bias slit  28  closed. Specifically, frame  30  is deformed by applying a small force on opposing sides that cause it to take on an elliptical shape. Frame  30  is then positioned relative to slit  28  such that the longitudinal axis of slit  28  is aligned with the longitudinal, uncompressed axis of frame  30 .  
      Deforming frame  30  is relatively easy, because its small size makes it quite malleable. A slight force applied on each side of frame  30  is enough to deform it into the elliptical shape. After being overmolded with septum  26 , frame  30  may be deformed prior to or as it is being attached to tower  18 . Because tower  18  is much more rigid, it will maintain frame  30  in the elliptical configuration after they are bonded together.  
      To finish connector  10   a , bottom edge  16   a  of body  16  is placed into slot  22   c  of base  22 . Because body  16  and base  22  are fabricated from the same or same class of material, they are readily bonded by any of a number of ways such as ultrasonic welding, solvent bonding, adhesive bonding, etc. As seen in  FIG. 1B , the components of housing  12  create a channel through connector  10   a . Septum  26  acts as resealable seal that allows fluid to pass through when septum  26  is opened by a tubular portion of a medical device.  
      The bonded parts are shown in more detail in  FIG. 1C .  FIG. 1C  shows septum  26  fused to frame  30  at fused interface  36 . Frame  30  is, in turn, bonded to tower  18  at bonded interface  38 . It should be noted that septum  26  and frame  30  may be altered such that interface  36  is not tapered but instead, is straight.  
      The present invention improves the manufacture of connector  10   a  by eliminating the use of adhesive to bond housing  12  and septum  26 , which is labor intensive and requires very tight process controls. Thus, restrictions on scaling up to high volume production are reduced. In addition, fused interface  36  is stronger and more consistent than the adhesive bonds. Variations in the configuration of frame  30  may provide additional advantages. For example, the ring may contain reduced cross-sectional areas that allow it to bend in certain directions or geometry that provides mechanical attachment instead of or in addition to the chemical or fused adhesion. Examples of these variations are described below.  
       FIGS. 2A-2D  show components of a representative embodiment of access connector  10   b .  FIG. 2A  shows frame  40 , which includes compression regions  42   a  and ring segments  42   b . Compression regions  42   a  have a reduced cross-section relative to arms  42   b . This makes compression regions  42   a  relatively weak and allows frame  40  to strategically bend to compress slit  28 .  
       FIG. 2B  shows frame  40  molded to septum  44  to form septum assembly  47 . Septum  44  includes slit  28  and projections  46 , which are in line with slit  28 . Projections  46  encompass compressed regions  42   a  and aid in preventing relative rotation between septum  44  and frame  40 .  
       FIG. 2C  shows the combination of frame  40  and septum  44  attached at rim  18   a  to tower  18 . Fused interface  48  between frame  40  and septum  44  and bonded interface  50  between frame  40  and rim  18   a  are indicated. The is resulting access connector  10   b  is shown in  FIG. 2D .  
       FIGS. 3A-3  C show components of a representative embodiment of access connector  10   c .  FIG. 3A  shows arc segment  52   a , which forms a variation of a frame. Here, instead of a extending all the way around, one or more of arc segment  52   a  is used.  
       FIG. 3B  shows septum assembly  55  and tower  18 . Septum assembly  55  is the combination of two arc segments  52   a  to form frame  52  and septum  54 , which is then attached to rim  18   a . Fused interface  56  between frame  52  and septum  54  and bonded interface  58  between frame  52  and rim  18   a  of housing  12  are indicated. In this embodiment, because septum  54  encompasses much of frame  52 , it prevents septum  54  from rotating during use. In addition, frame  52  compresses slit  28  of septum  54  to maintain a closed system.  FIG. 3C  shows connector  10   c  assembled with frame  52  and septum  54 .  
       FIGS. 4A-4C  show components of access connector  10   d .  FIG. 4A  shows arc segment  60   a . Arc segment  60   a  includes spine  62   a  with ribs  62   b  extending substantially perpendicular from spine  62   a . Ribs  62   b  provide geometry to mechanically attach to a septum. Typically, at least two of arc segment  60   a  are used to form a frame.  
       FIG. 4B  shows septum assembly  55  and tower  18 . Septum assembly  55  is the combination of two arc segments  60   a  to form frame  60  and septum  64 , which is then attached to rim  18   a . Fused interface  66  between frame  60  and septum  64  and bonded interface  68  between ribs  62   b  and rim  18   a  are indicated.  
      As noted above, this configuration also provides a mechanical attachment that might be used in addition to or instead of the chemical adhesion. In this example the silicone material solidifies around frame  60  without fusion at the interface between the parts. This may provide enough mechanical attachment for the resulting access connector to properly perform. Additionally, frame  60  will bias slit  28  of septum  64  shut to maintain a closed system.  FIG. 4C  shows connector  10   d  assembled with frame  60  and septum  64 .  
      The configurations of frames presented above are only examples. Other geometries may also be used that will impart the advantages of the invention. In another example, arc segments  52   a  of connector  10   c  could be connected to each other to form a continuous ring structure. The connecting sections of the ring would have a smaller cross-sectional diameter to form compressed regions that bend in order to bias slit  28  of septum  54 . The same type of variation could also be formed with arc segments  60  of connector  10   d.    
      Another variation is shown in  FIG. 5 , which is a representative embodiment of connector  10   e . Connector  10   e  includes housing  12  with frame  70  and septum  72  with slit  28 . Here, frame  70  and septum  72  are similar to frame  14  and septum  26  of connector  10   a  except that frame  70  and septum  72  have a saddle configuration at the top of device  10   e . The saddle provides additional bias to compress slit  28  and may be combined with any configuration of connector  10  to give the advantage of biasing slit  28  closed in order to maintain a closed system.  
       FIG. 6  shows a method of forming the saddle shape of frame  70  and septum  72  of connector  10   e  by deforming or shaping frame  70 .  FIG. 6  shows septum assembly  74  with frame  70  and septum  72 , mandrel  76  with inner wall  76   a  and rim  78  and forming base  80  with inner wall  80   a  and rim  82 . Septum  72  includes top disk  72   a  and bottom disk  72   b.    
      Mandrel  76  is saddle-shaped along rim  78 , heated and coated to have a non-stick surface. Forming base  80  is saddle-shaped along rim  82  in a mating fashion with rim  78  and may or may not be heated and/or coated. Both mandrel  76  and forming base  80  are cylindrical as indicated by inner walls  76   a  and  80   a , respectively, and are sized such that rim  78  and rim  82  only contact frame  70 .  
      In operation, septum assembly  74  is inserted into forming base  80  such that top disk  72   a  is over rim  82  and bottom disk  72   b  is underneath forming base  80 . As shown in  FIG. 7 , when a force is applied to mandrel  76  as indicated by arrow  84 , rim  78  is pressed against frame  70 , which is in turn pressed against rim  82  of forming base  80 . The heat and pressure causes the thermoplastic material of frame  70  to form the saddle shape of mandrel  76  and forming base  80 .  
      Depending on the type of thermoplastic material used to fabricate frame  70 , septum assembly  74  may be retained between mandrel  76  and forming base  80  until the part cools in order to maintain the saddle shape. Septum  72  is fabricated from elastomeric silicone, which has a resilient quality, and therefore will have a tendency to return to its original shape. If frame  70  is not stiff enough when hot to hold the saddle shape, then septum assembly  74  will need to remain between mandrel  76  and forming base  80  until cool. On the other hand, if frame  70  is stiff enough when hot it can be removed and allowed to cool without the support of mandrel  76  and forming base  80 .  
       FIG. 8  shows septum assembly  74  after being shaped. Septum assembly  74  is subsequently inserted into and attached to housing  12  to form connector  10   e.    
      Molding the septum onto the first section of the housing in access connectors according to the present invention provides several advantages. The attachment between the parts is strong and consistent. In addition, the process overcomes some of the barriers associated with scaling up for high volume production.  
      Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.