Abstract:
A retracting tip for a catheter set has telescoping barrels and a spring loaded cannula. Telescoping of the barrels into each other releases the spring compression on the cannula and results in the cannula being withdrawn into said barrels.

Description:
This application is a continuation in part of application Ser. No. 09/620/929 filed Jul. 21, 2000. This application is related to Ser. No. 09/575,007 filed May 19, 2000 and U.S. Pat. No. 5,984,898 issued Nov. 16, 1999. 
    
    
     FIELD OF THE INVENTION 
     This invention relates generally to the collection and infusion of patient fluids, more specifically, to an assembly for coupling a catheter or other flexible tubular device with a retractable cannula/needle assembly. The retracting tip assembly includes two telescoping barrels and a collet which operate to automatically retract the needle into the interior of the barrels. 
     BACKGROUND OF THE INVENTION 
     Many medicaments and fluids are routinely infused and discharged fluids collected through a catheter system connected to the patient and a administration container or a collection container. The typical administration set has a pre-filled plastic bag or bottle connected to one end of a catheter. The catheter may be integrally formed with the bag or the bag may have a puncturable port for connection with a needle on one end of the catheter. The other end of the catheter usually has a needle/cannula for insertion into the patient intravenously or enterally. 
     Collection bags or containers are constructed much the same way, except that the bag or container is initially empty. To infuse or collect from a patient, the needle/cannula at the free end of the catheter is inserted through the dermal layer into the lumen of the blood vessel and taps in to the circulation system of a patient or into other parts of the body. The catheter may have a clamp or valve which is manipulated to open the passageway from the bag to the patient. Once the infusion bag is empty or the collection bag full, each may be disconnected from the patient. 
     The retractable cannula assembly with its contaminated needle presents the danger of an inadvertent needle stick to personnel handling the used equipment. Even trace amounts of body fluids from a person with Hepatitis, Acquired Immune Deficiency Syndrome (AIDS), and other infectious diseases, transferred into another&#39;s blood stream can transmit these diseases. Thus, what is needed in the art is a needle/cannula assembly that protects from inadvertent needle sticks. 
     SUMMARY OF THE INVENTION 
     A retracting tip for a catheter set has telescoping barrels and a spring loaded cannula. Telescoping of the barrels into each other releases the spring compression on the cannula and results in the cannula being withdrawn into the barrels. The retracting tip having a tubular adapter having one end for connecting with an end of the catheter, the adapter having another end connected to the rearward end of a tubular inner barrel. The forward end of the inner barrel telescoped into one end of a tubular outer barrel, the other end of the outer barrel having a restricted opening. The forward end of the inner barrel formed with an enlarged circumferential ring and carrying a resiliently expandable tubular collet engaging the restricted opening. The collet including a portion extending through the restricted opening of the outer barrel, the portion of the collet having an expanded dimension greater than the restricted opening. A tubular cannula holder is inserted through the collet with one end of the cannula holder extending through the collet and having a connection for removably attaching to a cannula. The cannula holder having a shoulder trap adjacent to the connection with the other end of said cannula holder disposed in the forward end of the inner barrel. The end of the cannula holder having an enlarged flange, a first resilient spring disposed in the outer barrel about said restricted opening with said spring engaging the circumferential ring of the inner barrel and urging the cannula holder toward the outer barrel. A shoulder trap engaging the portion of the collet thereby wedging the collet in the restricted opening. A second spring disposed in the collet about the cannula holder and engaging the enlarged flange thereby urging the cannula holder into the inner barrel. 
     An objective of the instant invention is to provide a needle assembly that causes the contaminated hypodermic cannula to retract into the assembly so that the needle is no longer exposed for accidental needle sticks. The retraction of the needle is automatically accomplished by the telescoping movement of one barrel into another barrel that activates a spring release mechanism. 
     It is a further objective of the instant invention to provide a retracting assembly that is attached to the cannula such that it does not interfere with the operation of the catheter set but is easily accessible for retraction of the needle. 
     Another objective of the instant invention is to provide a collet which expands and releases a spring biased needle retractor in response to the forward movement of the telescoping barrel. The forward end of the outer barrel carries a wedge which insures the collet fingers will spread apart upon forward movement of the collet. 
     It is still another objective to provide an inexpensive, easily manufactured and used retracting needle assembly with a retractable needle mechanism for safe disposal and prevention of diseases. 
     Other objectives and advantages of this invention will become apparent from the following description taken in conjunction with the accompanying drawings wherein are set forth, by way of illustration and example, certain embodiments of this invention. The drawings constitute a part of this specification and include exemplary embodiments of the present invention and illustrate objects and features thereof. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a longitudinal cross sectional view of the assembly; 
     FIG. 2 is a longitudinal cross sectional side view of the fluid collection assembly with the collet in the forward position; 
     FIG. 3 is a longitudinal cross sectional side view of the inner barrel; 
     FIG. 4 is a longitudinal cross sectional view of the forward end of the barrel; 
     FIG. 5 is longitudinal cross sectional view of the adapter of the present invention; 
     FIG. 6 is a longitudinal cross sectional view of the needle retractor; and 
     FIG. 7 is a longitudinal cress sectional view of the assembly in the retracted position. 
    
    
     DETAILED DESCRIPTION 
     As shown in FIGS. 1-2, the invention is a combination of a fluid collection tube holding device  20 . The device features a separately attached needle hub including a metal cannula  12  and a threaded attachment portion  14  cooperating with threads  15  on the needle retractor  30 . This connection may also be a Leur Lok or frictional fit. 
     The fluid collection tube holding device  20  includes a hollow inner barrel  60  which cooperates with a needle retractor  30  to draw the needle  10  into the inner barrel following use of the needle. This action is accomplished by telescoping inner barrel  60  into outer barrel  50 , as shown in FIG.  2 . The continued stroke of the barrel  60  moves collet  66  forward and releases needle retractor  30  which is then propelled by spring action into the body of inner barrel  60 . 
     The retracting tip assembly  20  is made up of an outer barrel or tube  50  and an inner barrel  60 . The inner barrel has a forward end  64  which has an additional seal element  62 , O-ring in this embodiment, held between the enlarged circumferential ring  44  and an adjacent second circumferential ring  45 , which seals the inner barrel to the inner surface of the outer barrel  50 . The inner barrel  60  has an enlarged circumferential ring  44  with a central aperture  75  on the forward end. Aperture  75  is sized to accommodate the needle retractor  30 . The enlarged circumferential ring  44  is sized to fit within the outer barrel. At the rear end of the inner barrel  60 , therte is a push element  46  which is provided to engage the user&#39;s thumb. 
     The rearward end of the inner barrel, shown in FIG. 3, has an annular fitting  80  that accepts an annular adapter  10 . The annular fitting  80  has a circumferential wall  81  surrounding the bore of the inner barrel  60 . The adapter  10  forms the connection between the retracting tip assembly  20  and the catheter  90 . As shown, the adapter  10  and the annular fitting  80  are separate pieces with a friction fit but they may be formed as one piece or adhered together or otherwise permanently bonded together. 
     The adapter  10 , as shown in detail in FIG. 5, has an outer circumferential wall  11  sized to frictionally engage the inside of the circumferential wall  81 . A concentric inner wall  12  of smaller diameter than the outer wall  11  forms a male connection for frictionally connecting a catheter  90 . When connected, the end  91  of the catheter is protected by the outer wall  11 . 
     The forward end  64  of the inner barrel  60  also includes a collet  66  which acts as a movable stop between the outer barrel and the needle retractor. The collet has slots  67  in the external funnel shape which creates a contracting and clamping effect for the collet as it is withdrawn through the opening  72  located at the forward end of the outer barrel  50 . The collet is biased into a clamping or retracted position by a short spring  68  which biases the inner barrel  60  rearwardly with respect to the outer barrel  50 . 
     The needle retractor  30 , shown in detail in FIG. 6, passes fluid to or from the patient&#39;s body through the needle  12  and the bore of the needle retractor  30  into the inner barrel  60 . If desired, the needle  12  may be separated from the assembly at the needle retractor  30  and another infusion bag or collection bag connected at the same site. 
     Details of the collet  66  of this embodiment are shown in FIG.  3 . The collet includes a plurality of slots  67  which allow for expansion and contraction of the collet as the exterior funnel shape of the collet is urged forwardly and rearwardly through the forward opening  72  in outer tube  50  of the fluid collection tube holding device  20 . The slots  67  are larger at the forward ends  73  of the collet and taper rearwardly. The forward ends  73  of the slots  67  are sized to accommodate the wedges  74 , shown in detail in FIG.  4 . When the collet  66  is urged rearwardly with respect to the outer barrel  50  by a short spring  68 , the slots  67  in the collet forward end are forced into a closed position, without interference from wedges  74 , reducing the diameter of the collet and clamping the holder  30 . This clamping and retention of the holder is helped by the trapped edge  31  which is present of the exterior of the holder  30 . The collet  66  clamps onto the holder just behind thee trapped edge. The trapped edge  31  is shown as an annular element in this embodiment, however, it can take on any shape which binds against the restricting edges of the collet  66  and retains the holder  30  in the forward end of the inner barrel  60 . 
     The retracting holder  30  is biased rearwardly by long spring  38  which pushes on the end cap  34  of the holder. To release the holder  30 , the collet  66  is expanded by forward movement of the collet  66  in response to contact with the inner barrel forward end  64  and  44 . The forward movement of the collet  66  frees the collet from the constriction of the opening  72  and engages the narrowed portions  75  of the slots  67  with the wedges  74  to force the collet to expand clear of the lip on the retracting holder  30 . As shown in FIG. 7, the shoulder trap  31  is freed from engagement with collet  66  and moves into inner barrel  60  under expansion of long spring  38  carrying cannula  12  into the assembly where it is enclosed. The contaminated cannula is held in the inner barrel  60  by the expanded long spring  38 . 
     To use the catheter set with the retracting tip assembly, the user may insert the needle  12  into the patient&#39;s body and then attach the assembly or use a preassembled cannula and assembly. The counterbalanced forces of the short spring and the long spring maintain the relative positions of the inner and outer barrels because the shoulder trap  31  wedges the collet  66  in the restricted opening  72 . The fluid flows through the needle  12  and the retracting holder  30  through the inner barrel  60  and the catheter  90 . 
     When the container is filled or emptied, the cannula is removed from the patient and the inner barrel  60  and outer barrel  50  are telescoped by bringing flanges  46  and  51  together. The user pushes until the annular forward end  44  of inner barrel  60  overcomes the wedging force of spring  68  which in turn pushes the collet  66  forward. By pushing forward, as shown in FIG. 2, the collet  66  expands and the holder  30  disengages from the collet  66  and the holder  30  is propelled rearwardly into the tubular body of the inner barrel  60 . The needle  12  is then disabled with the needle trapped within the assembly, as shown in FIG.  7 . 
     The assembly sequence of the present invention is as follows: The inner barrel  60  and the short spring  68  are loaded into the outer barrel  50  allowing the collet to extend through the restricted opening  72  and compressing the spring; the assembled holder  30  including the long spring  38  is inserted through the inner barrel and the extended collet; compression is released on the short spring by retraction of the inner barrel until the shoulder trap  31  engages the forward edge of the collet wedging the collet in the restricted opening of the outer barrel. The entire assembly includes very few polymer plastic molded parts, namely the adapter, outer and inner barrels, the holder with metal cannula hub and two springs. The optional seal can also be a polymer and consequently be molded together with the respective inner barrel and holder as desired. By virtue of the comparatively few numbers of parts and their simplicity in execution, the present assembly and retractable needle combination can be readily and economically manufactured. 
     It is to be understood that while I have illustrated and described certain forms of my invention, it is not to be limited to the specific forms or arrangement of parts herein described and shown. It will be apparent to those skilled in the art that various changes may be made without departing from the scope of the invention and the invention is not to be considered limited to what is shown in the drawings and described in the specification.