Abstract:
A blood collection assembly designed for one-time use includes a microcollection tube and an adapter for the tube which is sized to fit into the tube slot of an automated analytical instrument. The adapter includes structure which forms a tight and permanent interference fit with the microtube so that the tube, once inserted into the adapter, cannot be removed by hand, and the assembly, after sampling and analysis, must be discarded in one piece.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to blood microcollection assemblies, and more particularly relates to a microcollection assembly which is compatible with analytical instrumentation. 
     2. Background 
     In modern medical practice, a variety of chemical and hematological diagnostic procedures are carried out on very small quantities of blood. In recent years, many collection assemblies have been disclosed for drawing, transporting and analyzing these small samples. In order to protect a phlebotomist or technician from contact with a contaminated blood sample, it has become conventional to draw these samples in equipment designed for single use followed by strict throw away procedures. Nevertheless, it does happen that attempts are made to reuse such equipment, either through operator error or misguided attempts to achieve economy. 
     In designing collection assemblies, an important factor to consider is compatibility of the blood sampling equipment with modern automated instrumentation. Thus, the small containers advantageously used are often not compatible with instruments designed generally for larger containers. 
     Adapters to render small sample collection tubes instrument-compatible have been disclosed. These adapters, however, are not designed for single use and instead provide means to separate the adapter from the collection tube for reuse after analysis. Reuse subjects the user to possible contact with a potentially dangerous blood sample. 
     There is a need in the art of blood collection for a device which would modify a microcollection tube to a size and shape which would enable its insertion directly into an automated blood analyzer, and at the same time have structure assuring one time throw-away use which cannot be defeated by a user wishing to reuse all or part of the assembly. It is toward fulfillment of this need that this invention is directed. 
     SUMMARY OF THE INVENTION 
     One aspect of the invention is an adapter for a blood microcollection container which renders the container compatible with automated analytical instruments. The adapter includes a sleeve dimensioned to fit into the slot of the instrument. A shelf which serves as a false bottom divides the sleeve into upper and lower segments which separate the interior volume of the sleeve into upper and lower regions. A tubular body in the upper region projects upwardly from the shelf and has structure thereon to form a permanent interference fit with a microcollection container inserted through an open end of the sleeve. 
     In an alternate embodiment of the adapter, the sleeve has longitudinal ribs on the inside surface of its upper segment which form an interference fit with the tube. 
     Another aspect of the invention is a blood microcollection assembly which includes the adapter, a microcollection container therein and a cap for the container. 
     Thus, the invention provides an instrument-compatible assembly for blood sampling in which the tube and adapter are permanently affixed by structure which prevents their being separated so that a user cannot defeat the one-time use only purpose of the assembly. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of the tube and cap of the invention; 
     FIG. 2 is a perspective view of the adapter of the invention; 
     FIGS. 3 and 4 are vertical and horizontal sectional views respectively of the adapter of FIG. 2 taken along the lines  3 — 3  and  4 — 4  thereof; 
     FIG. 5 is a perspective view of the assembly of the invention; 
     FIGS. 6 and 7 are vertical and horizontal sectional views respectively of the assembly, taken along the lines  6 — 6  and  7 — 7  of FIG. 5, with the tube in the adapter; 
     FIGS. 8 and 9 are sectional views of an alternative embodiment of the invention; and 
     FIG. 10 is a horizontal sectional view of an embodiment of the invention combining the features of FIGS. 6 and 8. 
    
    
     DETAILED DESCRIPTION 
     While this invention is satisfied by embodiments in many different forms, there will herein be described in detail preferred embodiments of the invention, with the understanding that the present disclosure is to be considered as exemplary of the principles of the invention and is not intended to limit the invention to the embodiments illustrated and described. The scope of the invention will be measured by the appended claims and their equivalents. 
     The invention contemplates an adapter dimensioned to render any conventional blood microcollection container compatible with the container slot of an automated analysis instrument Such slots are generally 13 or 16 mm in external diameter and 75 or 100 mm long. Preferred microcontainers are Microtainer® Brand blood collection tubes sold by Becton Dickinson and Co. and the invention will henceforth be described for a microcollection tube. These preferred tubes and mating caps are fully described in U.S. Pat. No. 5,458,854 to Burns. Another aspect of the invention is a blood collection assembly in which a tube and mating cap are positioned in the adapter. 
     Adverting now to the drawings, FIG. 1 illustrates a preferred tube-cap unit  10  as disclosed in the aforementioned U.S. Pat. No. 5,458,854. Unit  10  includes a blood microcollection tube  12  having cap  14  covering an open top end thereof. Tube  12  has side wall portion  16  with outside wall surface  17  and bottom wall  18 . Skirt  20  depends downwardly from sidewall  16  and is integral therewith. (In this disclosure the term integral means continuous, such as formed by injection molding). Skirt  20  has outside wall surface  22  and inside wall surface  24 . 
     FIGS. 2 and 3 illustrate the adapter of the invention. In FIG. 2, adapter  30  is shown to include a sleeve  32  having inside wall surface  33  and an open top end  34 . An integral bottom wall  36  is preferably curved as shown to form a better fit in a slot of an automated instrument. Sleeve  32  has upper segment  38  and lower segment  39 . Lower segment  39  of sleeve  32  may preferably be textured (not shown in the drawing), as for example by conventional etching or frosting. The texture mimics an adapter slot filled to the top of the texture and causes the instrument sensor to move up and thereby read a tube in the upper segment  38 . Adapter  30  includes structure  40 , shown in phantom in FIG.  2  and in section in FIG.  3 . 
     In FIG. 3, details of structure  40  are illustrated. (In the drawings, elements which are the same or substantially the same in the various embodiments of the invention are given the same reference number followed by a lower case letter). A shelf  42 , which serves as a false bottom for adapter  30   a , positions a tube (not shown) to be immobilized in the adapter at the proper position for reading a bar code on the tube when the assembly of the invention is inserted in an automated analyzer. Shelf  42  may be either a disc or a rim. Tubular body  44  projects perpendicularly up from shelf  42  and has, on its outside wall surface  46 , a plurality of rounded protuberances  48  integral with body  44 . FIG. 4 is a sectional view of the adapter of FIG. 2 showing details of structure  40  as seen from the top. 
     The tube-cap unit and the adapter may be combined in a blood collection assembly. As shown in FIGS. 5-7, assembly  60  includes adapter  30   b  having inside wall  33   b , shelf  42   b  and tubular body  44   b  with integral protuberances  48   b . Tube  12   b  having skirt  20   b  is permanently immobilized in adapter  30   b  by a tight interference fit between skirt inside wall  24   b  and protuberance  48   b . It is seen that outside wall surface  17   b  of the tube is spaced at a distance  66  from inside wall surface  33   b  of adapter  30   b . This space assures that any label, such as a patient information label previously applied to the tube, will not be scratched, crumpled, jammed or in any way be rendered illegible when the tube is immobilized in the adapter. 
     Another embodiment of the invention is illustrated in FIGS. 8 and 9. In this embodiment, inside wall surface  33   c  of adapter  30   c  has a longitudinal rib  70  integral therewith so that the interference fit which immobilizes the tube in the adapter occurs between the outside surface  17   c  of the tube and the rib. In this embodiment, the interference fit between the outer surface of the tube and the rib leaves space  72  (FIG. 9) so that, in this arrangement, a label on the outside of the tube will not be defaced when the tube is inserted into the adapter. 
     Still another embodiment of the invention, illustrated in FIG. 10, combines the immobilization features of FIGS. 6 and 8. Inside wall surface  33   d  of the adapter  30   d  has longitudinal rib  70   d  integral therewith. Rib  70   d  forms an interference fit with the outside wall surface  17   d  of tube  12   d , as in the embodiment of FIGS. 8 and 9. In addition, the inside wall surface  24   d  of the tube skirt forms an interference fit with protuberance  48   d  on tubular body  44   d , as in the embodiment of FIGS. 5 to  7 . The double interference fit thereby achieved between the adapter and both the inside and outside wall surfaces of the tube provides even greater assurance that the interlock between the tube and the adapter cannot be overcome by a user attempting to defeat its purpose. 
     The adapter of the invention may be of any plastic suitable for injection molding, such as polyethylene, polypropylene or polyvinyl chloride. The preferred adapter is clear plastic, preferably textured as described above, so that the bar code or any patient label on the tube can be read directly through the sleeve wall. The adapter may be of several molded parts affixed together into a single unitary device, or most preferably, may be injection molded into a single, integral device in which all components are continuous.