Abstract:
A syringe for sequentially administering different fluids includes a floating piston which separates the syringe into a first portion for receiving a first fluid to be administered and a second portion for receiving a second fluid to be administered. The floating piston includes a fluid tight seal which initially separates the first and second portions of the syringe and a piercing needle which penetrates the fluid tight seal to connect the second portion of the syringe to the syringe needle after the first fluid has been discharged from the syringe.

Description:
TECHNICAL FIELD  
         [0001]    This invention relates generally to the sequential administration of different fluids, for example, the administration of a medication followed immediately by the administration of a normal saline solution, and more particularly to an improved syringe design which assures complete delivery of the first fluid followed immediately by complete delivery of the second fluid.  
         BACKGROUND AND SUMMARY OF THE INVENTION  
         [0002]    Various medical procedures require the sequential administration of different fluids. For example, administration of the cardiac drug known as Adenosine must be followed immediately by the administration of a normal saline solution in order to get the drug into circulation rapidly. Heretofore the sequential administration of different fluids has been accomplished utilizing two syringes, one loaded with the first fluid to be administered and the other loaded with the second fluid to be administered. The two needle system is not only awkward but also increases the risk that medical personnel will suffer inadvertent needlesticks.  
           [0003]    A previous attempt to solve the foregoing problem is shown and described in published U.S. patent application US 2002-0035351-A1. Referring to FIG. 1 of the present application, the device disclosed in the published application comprises a single barrel double chamber syringe  10  having a barrel  1  and a plunger  2  which is utilized in the conventional manner to force fluids contained within the barrel  1  outwardly through a hollow needle  8 . This is accomplished by means of a push stopper  3  secured to the plunger  2  and made of a pliable material to maintain a fluid tight seal around its outer periphery. A hollow floating plunger  5  situated within the barrel  1  is likewise comprised of a pliable material to maintain a fluid tight seal around its outer periphery. The floating plunger  5  divides the barrel  1  into a first compartment  4  and a second compartment  6 .  
           [0004]    The hollow needle  8  is secured in a hub  9  situated at the opposite end of the barrel  1  from the plunger  2 . The hollow needle  8  comprises a first component extending outwardly from the barrel  1  and the hub  9  and a piercing component extending from the hub  9  into the second chamber  6  of the barrel  1 . The hollow needle  8  is provided with a porthole  7  to assure full delivery of fluid contained within the second chamber  6 .  
           [0005]    In the operation of the syringe  10  a first fluid is loaded into the second chamber  6  and a second fluid is loaded into the first chamber  4 . As the push stopper  3  is forced downwardly (FIG. 1) into the barrel  1  under the action of the plunger  2  the fluid within the first chamber  4  and the floating plunger  5  function to force the first fluid outwardly from the second chamber  6  through the hollow needle  8 . As the floating plunger  5  moves downwardly it eventually engages the piercing component of the hollow needle  8  which begins to penetrate the floating chamber  5 . Meanwhile, the remainder of the first fluid is forced out of the second chamber  6  through the porthole  7  and the hollow needle  8 .  
           [0006]    Continued downward movement of the push stopper  3  under the action of a plunger  2  causes the piercing component of the hollow needle  8  to fully pierce the floating plunger  5  thereby allowing the second fluid to flow outwardly from the first chamber  4  through the hollow needle  8 . Movement of the push stopper  3  toward the hollow needle  8  under the action of the plunger  2  continues until all of the second fluid has been discharged from the syringe  10  through the hollow needle  8 .  
           [0007]    While eliminating the problems inherent in sequentially administering two different fluids utilizing two syringes, the device shown and described in published application US-2002-0035351-A1 involves different problems. First, the hollow needle through which the different fluids are sequentially administered must be provided with a porthole. As will be appreciated by those skilled in the art, forming a porthole in a hollow needle of the type utilized in medical syringes involves difficult and expensive manufacturing steps. Second, the axial dimensions of the hollow needle utilized in the device disclosed in the published application must be very accurately controlled. Thus, if the piercing component of the needle is too short the floating plunger will not be properly penetrated thereby preventing proper administration of the second fluid. Conversely, if the piercing component of the hollow needle is too long complete delivery of the first fluid cannot be assured.  
           [0008]    The present invention comprises an improved syringe design which overcomes the foregoing and other problems that have long since characterized the prior art. In accordance with the broader aspects of the invention an otherwise conventional syringe is provided with a floating piston comprising upper and lower portions. The lower portion may comprise a spongy material encased in a flexible shell and having a piercing needle mounted therein. Alternatively, the lower portion may comprise a flexible shell filled with a suitable gas such as air. The upper portion comprises a seal formed from a non-coring elastomeric material.  
           [0009]    In the practice of the invention a first fluid to be administered is loaded into the barrel of the syringe below the floating piston. A second fluid to be delivered is loaded into the barrel of the syringe above the floating piston. As the plunger of the syringe is moved into the barrel the first fluid is forced outwardly through the needle of the syringe under the action of the second fluid and the floating piston. The floating piston eventually engages the discharge end of the barrel thereby forcing the entirety of the first fluid outwardly through the needle. Continued movement of the plunger of the syringe causes the penetrating needle of the floating piston to penetrate the seal comprising the upper portion of the floating piston. At this point the second fluid is connected in fluid communication with the syringe needle through the penetrating needle of the floating piston. Further inward movement of the plunger of the syringe forces all of the second fluid outwardly through the penetrating needle of the floating piston and the syringe needle.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    A more complete understanding of the invention may be had by reference to the following Detailed Description when taken in conjunction with the accompanying Drawings, wherein:  
         [0011]    [0011]FIG. 1 is a longitudinal sectional view of a prior art single barrel double chamber syringe;  
         [0012]    [0012]FIG. 2 is a longitudinal sectional view of the syringe of the present invention showing the syringe in a first stage of its operation;  
         [0013]    [0013]FIG. 3 is an enlargement of a portion of FIG. 2;  
         [0014]    [0014]FIG. 4 is a view similar to FIG. 2 showing the syringe at a later stage in its operation;  
         [0015]    [0015]FIG. 5 is a view similar to FIG. 2 showing a syringe of the present invention at a still later stage in its operation; and  
         [0016]    [0016]FIG. 6 is an illustration similar to FIG. 2 showing a syringe of the present invention at the completion of its operation.  
     
    
     DETAILED DESCRIPTION  
       [0017]    Referring now to the Drawings, and particularly to FIG. 2 thereof, there is shown a syringe  20  incorporating the present invention. In many respects the syringe  20  is conventional in construction and operation. Thus, the syringe  20  includes a barrel  22  which receives fluid to be administered. A hollow needle  24  is secured to one end of the barrel  22  by a hub  26  and is coupled in fluid communication with the interior of the barrel  22 . The end of the barrel  22  remote from the needle  24  may be provided with a radially extending flange  28  which is typically engaged by the fingers of an individual operating the syringe  20 .  
         [0018]    The syringe  20  further includes a plunger  30  adapted for axial movement within the barrel  22 . The plunger  30  extends to a piston  32  which forms a fluid tight seal with the interior surface of the barrel  22 . The end of the plunger  30  remote from the piston  32  may be provided with a plate  34  which is typically engaged by the thumb of an individual operating the syringe  20 .  
         [0019]    Referring to FIGS. 2 and 3, the syringe  20  differs from conventional syringes in that it is provided with a floating piston  40 . The floating piston  40  includes a lower portion  42  and an upper portion  44 .  
         [0020]    Referring particularly to FIG. 3, the lower portion  42  of the floating piston  40  comprises a body  46  formed from a resilient material which may be spongy in nature. The body  46  is surrounded by a flexible layer  48  formed from a material approved for medical applications, for example, silicone. Alternatively, the lower portion  42  may comprise a flexible shell filled with a suitable gas such as air. The lower portion  42  of the floating piston  40  further comprises a piercing needle  50 . The piercing needle  50  is mounted and supported by the body  46  of the lower portion  42  of the floating piston  40 .  
         [0021]    The piercing needle  50  is hollow throughout its length and is preferably either equal to or greater in diameter than the needle  24  of the syringe  20 . The piercing needle  50  may be provided with an enlarged portion at the end thereof facing the needle  24  of the syringe  20  in order assure fluid communication between the piercing needle  50  and the syringe needle  24 .  
         [0022]    The upper portion  44  of the floating piston  40  comprises a non-coring elastomeric material. In use, the upper portion  44  forms a fluid tight seal with the interior surface of the barrel  22  of the syringe  20 . As will be appreciated by those skilled in the art, the function of the upper portion  42  of the floating piston  40  is to divide barrel  22  of the syringe  20  into upper and lower chambers and to initially maintain a fluid-tight barrier therebetween.  
         [0023]    Operation of the syringe  20  of the present invention is illustrated in FIGS. 2, 4,  5 , and  6 . Referring first to FIG. 2, a first fluid to be administered is loaded into the portion of the barrel  22  of the syringe  20  situated below the floating piston  40 . A second fluid to be administered immediately following completion of the delivery of the first fluid is loaded into the portion of the barrel  22  of the syringe  20  situated above the floating piston  40 . The floating piston  40 , and particularly the upper portion  42  thereof, comprises a fluid tight seal which maintains separation between the two fluids.  
         [0024]    Referring next to FIG. 4, administration of the first fluid is accomplished by moving the plunger  30  inwardly, that is, from the position illustrated in FIG. 2 toward the position illustrated in FIG. 4. As the plunger  30  is moved inwardly, the floating piston  40  and the second fluid positioned within the barrel  22  of the syringe  20  betweeen the floating piston  40  and the plunger  30  function to force the first fluid out of the barrel  22  through the syringe needle  24 . FIG. 4 illustrates the floating piston  40  bottomed out in the barrel  22  of the syringe  20  with all of the first fluid having been delivered through the syringe needle  24 .  
         [0025]    Referring next to FIG. 5, further inward movement of the piston  30  compresses the resilient material  46  and/or the gas comprising the lower portion  42  of the floating piston  40  thereby causing the piercing needle  50  to penetrate the upper portion  44  of the floating piston  40 . In this manner the second fluid to be administered, which is situated between the floating piston  40  and the plunger  30 , is connected in fluid communication with the syringe needle  24  through the hollow interior of the piercing needle  50 . Further inward movement of the plunger  30  forces the second fluid to be administered out of the barrel  22  of the syringe  20  through the piercing needle  50  and the syringe needle  24 . This action continues until the piston  32  of the plunger  30  bottoms out as illustrated in FIG. 6. At this point the syringe  20  is typically disposed of in accordance with approved syringe disposal techniques.  
         [0026]    It will therefore be understood that the present invention comprises a syringe for sequentially administering different fluids which overcomes the problems that have characterized the prior art. In particular, manufacture of the syringe of the present invention involves the addition of a unique floating piston to an otherwise conventional syringe. Manufacture of the components parts of the syringe of the present invention does not involve complicated and expensive manufacturing techniques, nor does it involve precise control over the dimensions of the component parts of the device.  
         [0027]    Although preferred embodiments of the invention have been illustrated in the accompanying Drawings and described in the foregoing Detailed Description, it will be understood that the invention is not limited to the embodiments disclosed, but is capable of numerous rearrangements, modifications, and substitutions of parts and elements without departing from the spirit of the invention.