Abstract:
A retractable blood collection device having a housing comprised of relatively rotatable parts and a hub in the housing supporting a double ended cannula which is retracted by spring pressure into the housing when the housing parts are rotated to contain the used cannula in the housing for safe disposal.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS, IF ANY 
     None 
     BACKGROUND OF THE INVENTION AND PRIOR ART 
     The present invention relates to a medical apparatus for safely drawing blood or other fluid from a patient wherein the apparatus includes a cannula housing into which the cannula can be withdrawn and contained after use for safe disposal. 
     OBJECTS OF THE INVENTION 
     It is the primary object of the invention to provide a blood collection device in which the cannula may be automatically retracted into a housing by a spring after use merely by turning easily manipulatable rotatable parts of the housing to permit a non-circular portion of the cannula support to pass through a non-circular opening in an end of the housing to withdraw the cannula into the housing. 
     It is a further object of the invention to provide a reliable blood collection device comprised of a small number of parts, each of which are easily formed in mass production. 
     SUMMARY OF THE INVENTION 
     The present invention accordingly provides a retractable blood collection device comprising: 
     a) an elongated tubular housing having an end wall partially closing a first end of said housing; 
     b) a cannula support hub slidably supported in said housing for longitudinal movement therein; 
     c) a cannula affixed to and supported by said hub, said cannula having a first end extending from a first side of said hub exteriorly of said housing through said housing end wall, said cannula having a second end extending from a second side of said hub in said housing, said housing having a greater length than said cannula; 
     d) a cannula retainer ring rotatably affixed to said first end of said housing, said retainer ring having a centrally located aperture through which a portion of said hub and cannula protrude; and 
     e) a compression spring in said housing seated between said hub and said first end of said housing biasing said hub for retracting said first end of said cannula into said housing to position said cannula completely in said housing. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the accompanying drawings: 
     FIG. 1 is a perspective view of a housing for the blood collection device. 
     FIG. 2 is a left side elevation view of the housing showing the end cover. 
     FIG. 3 is a right side elevation view of the housing. 
     FIG. 4 is a perspective view of a cannula support hub. 
     FIG. 5 is cross sectional plan view of the cannula support hub. 
     FIG. 6 is a right side elevation view of the cannula support hub. 
     FIG. 7 is a perspective view of a cannula retainer ring. 
     FIG. 8 is a left side elevation of the retainer ring. 
     FIG. 9 is a longitudinal cross section of the assembled blood collection device. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 is a perspective view of an elongated generally cylindrical housing  10 , preferably made of polypropylene plastic. The elongated tubular housing has a cylindrical side wall  12  and transversely extending end wall  14  which partially closes the right end of the housing as seen in the drawing. The left end of the housing  10  includes an integrally formed finger gripping collar  16  and plastic cover  20  connected to the housing by a hinge  30  of any suitable type, but preferably an integrally formed plastic hinge  30  which has elastic memory to bias the cover  20  to a position in which it ordinarily closes the open left end of the housing. The cover  20  also includes an integrally formed generally semi-circular guide skirt  22  on the inner side wall of the cover which is closely received in the interior of the preferably generally cylindrical wall  12  of the housing. The inherent elasticity of the materials of the cover and housing retain the cover in the closed position but permit easy opening thereof by finger pressure. As seen in FIG. 1, the longitudinally extending wall  12  of the housing is configured with a thickened section to provide a seat  18  of reduced diameter to prevent passage of a cannula support hub  60  (FIGS.  4 - 6 ) to the left past the seat. 
     FIGS. 1 and 3 illustrate the right end of the housing including the transversely disposed end wall  14  which terminates in an integrally formed axially extending cylindrical end  15  of reduced diameter. An annular rounded retainer enlargement  24  and a reduced diameter restraining groove  26  on the exterior of the cylindrical wall  12  of the housing mate with the interior wall of a retainer ring  50  to be described with reference to FIGS. 7 and 8 for holding the retainer ring on the end of the housing while permitting relative rotation between the retainer ring  50  and housing  10 . The retainer ring  50  is preferably made of polypropylene plastic so that the retainer ring  50  can be elastically pressed onto the end of the housing to be retained thereon by the enlargement  24  and groove  26 . Engageable rotation limit stops  42 ,  44 ,  52  are provided on the exterior surface of the end wall  14  of the housing and interior surface of the retainer ring  50  to limit relative rotation therebetween preferably to not exceed about 45° so that the ring  50  can easily be rotated manually relative to the housing  10  with one hand without having to shift the position of the user&#39;s hand. The rotation limit stops  42 ,  44  on the end of the housing can take any suitable form but, as shown, comprise the ends of an annular skirt  40  which are positioned for abutment with the rotation limit stop  52  on the retainer ring. 
     In order to tactilely determine the relative position of the retainer ring  50  and housing  10 , two circumfrentially spaced buttons or enlargements  46 ,  48  are provided on the outside of the end wall  14  of the housing positioned in the arc of the annular stop skirt  40  between the stops  42 ,  44  provided by the ends thereof. The rotation limit stop  52  on the retainer ring  50  is sized to snap into one or the other of the recesses between the limit stops  42 ,  44  and the enlargements  46 ,  48  to enable the user to feel whether the retainer ring is  50  in correct position relative to the housing  10 . As seen in FIG. 7, the retainer ring is a generally cup shaped part having an exterior finger gripping surface  54  preferably formed by grooves or enlargements. As seen in FIG. 8, the retainer ring  50  has a non-circular central opening  56  which may take the shape of a rectangle, and the rotation limit stop  52  is integrally formed and extends radially inwardly from the side wall of the retainer ring to engage the stops  42 ,  44  provided by the ends of the annular skirt on the end wall of the housing  10 . The stop  52  in the retainer ring  50  has an end surface  56  receivable in the spaces between the enlargements  46 ,  48  on the exterior surface of the end wall  14  of the housing and the stops  42 ,  44  provided by the ends of the annular housing skirt  40 . 
     A generally cup-shaped cannula support hub  60  (FIGS.  4 - 6 ), preferably also made of polypropolene plastic, is comprised of a transversely extending disk  62  and an axially extending skirt  64 , preferably having two or more spaced annular sections  64   a ,  64   b  and a centrally located cannula support  66  having a non-circular portion  68 , which for example may be rectangular or square, integrally formed on its end for passage through the opening  56  in the retainer ring  50 . Preferably, the hub also includes an integrally formed retainer  70  having an enlarged lip  72  suitable for retaining a rubber or plastic protective boot  74  initially covering the left end of a double ended cannula  80  firmly supported in a centrally disposed passageway  82  which extends through the hub  60 . The cannula  80  may be permanently attached in the cannula support  66  or the cannula passage in the support  66  may be threaded to receive a cannula of the user&#39;s choice. A permanently attached cannula will have one end which initially protrudes from the housing with the cannula  80  extending from each side of the hub  60  as seen in FIG. 9 which shows the assembled blood collection device. The centrally located non-circular opening  56  in the retainer ring  50  is sized to prevent passage of the non-circular end  68  of the cannula support  66  therethrough when the retainer ring  50  is in a first rotational position with respect to the hub  60  and housing  10  with the opening  56  permitting passage of the end  68  of the cannula support  66  therethrough when the retainer ring  50  is rotated to a second position with respect to the hub and housing. 
     A coil compression spring  90  (FIG.  9 ), preferably of stainless steel, is seated in the housing between the hub disc  62  and the transversely extending end wall  14  of the housing to bias the hub  60  and cannula  80  supported therein to the left so that the double ended cannula  80  is completely enclosed within the housing after use. The compression spring  90  may be cylindrical or, as shown, of generally conical shape and closely surrounds the elongated cannula support  66  to prevent mis-alignment of the hub  60  as it longitudinally slides in the housing  10  to its engagement with the seat  18  where continued leftward motion of the hub and supported cannula is terminated. 
     The spaces between the annular skirt portions  64   a ,  64   b  of the hub conveniently form keyways for receiving longitudinally extending keys  92  integrally formed on the interior cylindrical wall of the housing as seen in FIGS. 1 and 2 to guide the hub  60  in its sliding movement in the housing and prevent relative rotation therebetween. 
     The assembled device preferably also is shipped with a protective sheath  100  of rubber, plastic or otherwise elastically stretchable material for covering the projecting end of the cannula  80  prior to use. The sheath is frictionally retained on the non-circular end  68  of the cannula support which essentially comprises a lip for elastically retaining the sheath. 
     In operation, the elastic boot  74  or cover over the interior end of the double ended cannula  80  is first removed then a suitable blood collection container having a piercable end is inserted into the open end of the housing where it is pierced by the inner end of the cannula  80 . The outer protective sheath  100  covering the cannula is then removed, the blood collection device used in its intended fashion, and, after drawing of the blood sample, the cannula  80  is removed from the patient&#39;s vein. The retainer ring  50  is then easily rotated, preferably clockwise, relative to the housing with one hand through its path of travel to permit the non-circular end  68  of the cannula support hub to align with the non-circular opening  56  in the retainer ring  50  to permit the spring  90  to passively withdraw the end  68  of the cannula support hub and the cannula  80  completely into the housing  10  for safe disposal. 
     While the foregoing constitutes a complete description of the preferred embodiment, it will be appreciated by persons skilled in the art that modifications can be made from the preferred embodiment and the scope of protection is defined by the following claims.