Patent 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 apparatus for connecting the second portion of the syringe to the syringe needle after the first fluid has been discharged from the syringe.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is a continuation-in-part application of application Ser. No. 10/231,827 filed Aug. 30, 2002 abandoned. 

   TECHNICAL FIELD 
   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 
   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. 
   A previous attempt to solve the foregoing problem is shown and described in published U.S. patent application Ser. No. 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 . 
   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 compartment  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 compartment  6 . 
   In the operation of the syringe  10  a first fluid is loaded into the second compartment  6  and a second fluid is loaded into the first compartment  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 compartment  4  and the floating plunger  5  function to force the first fluid outwardly from the second compartment  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 compartment  5 . Meanwhile, the remainder of the first fluid is forced out of the second compartment  6  through the porthole  7  and the hollow needle  8 . 
   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 compartment  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 . 
   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. 
   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 a first embodiment 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. 
   In the practice of the first embodiment 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. 
   In accordance with a second embodiment of the invention an otherwise conventional syringe is divided into upper and lower chambers by a floating piston. The floating piston comprises a resilient, spongy material and has an aperture extending therethrough from top to bottom. The aperture may be axially disposed and circular in cross-section, however, neither the location nor the shape of the aperture is critical to the practice of the invention. A substantially rigid valve extends through the aperture of the floating piston. The upper end of the valve comprises an imperforate sealing disk. The lower end of the valve comprises an open construction to allow the passage of fluid therethrough. 
   The length of the valve is slightly less than the thickness of the floating piston such that the piston is normally slightly compressed thereby maintaining the sealing disk in sealing engagement with the upper end of the passageway. As the plunger of the syringe is moved axially through the barrel thereof toward the needle of the syringe, the fluid in the portion of the barrel extending above the floating piston forces the floating piston toward the needle of the syringe thereby forcing the fluid in the lower portion of the barrel of the syringe outwardly through the needle. When the floating piston bottoms out at the needle end of the syringe, further movement of the plunger compresses the spongy material comprising the floating piston thereby disengaging the sealing disk from the upper end of the passageway through the floating piston. This allows the fluid that was originally in the end of the barrel of the syringe remote from the needle thereof to pass through the aperture in the floating piston and outwardly through the needle of the syringe. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     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: 
       FIG. 1  is a longitudinal sectional view of a prior art single barrel double chamber syringe; 
       FIG. 2  is a longitudinal sectional view of a first embodiment of the syringe of the present invention showing the syringe in a first stage of its operation; 
       FIG. 3  is an enlargement of a portion of  FIG. 2 ; 
       FIG. 4  is a view similar to  FIG. 2  showing the syringe at a later stage in its operation; 
       FIG. 5  is a view similar to  FIG. 2  showing a syringe of the present invention at a still later stage in its operation; 
       FIG. 6  is an illustration similar to  FIG. 2  showing a syringe of the present invention at the completion of its operation; 
       FIG. 7  is a longitudinal sectional view of a second embodiment of the syringe of the present invention showing the syringe in a first stage of its operation; 
       FIG. 8  is a view similar to  FIG. 7  showing the syringe at a later stage in its operation; 
       FIG. 9  is a partial perspective view of the floating piston of the syringe of  FIG. 7 ; and 
       FIG. 10  is a sectional view further illustrating the floating piston of the syringe of FIG.  7 . 
   

   DETAILED DESCRIPTION 
   Referring now to the Drawings, and particularly to  FIG. 2  thereof, there is shown a syringe  20  comprising a first embodiment of 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 . 
   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 . 
   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 . 
   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 . 
   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 to assure fluid communication between the piercing needle  50  and the hollow needle  24 . 
   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 lower 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. 
   Operation of the syringe  20  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. 
   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 hollow 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 hollow needle  24 . 
   Referring next to  FIG. 5 , further inward movement of the piston  32  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 hollow 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 hollow 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. 
   Referring to  FIGS. 7 through 10 , inclusive, there is shown a syringe  60  comprising a second embodiment of the present invention. In many respects the syringe  60  is conventional in construction and operation. Thus, the syringe  60  includes a barrel  62  which receives fluid to be administered. A hollow needle  64  is secured to one end of the barrel  62  by a hub  66  and is coupled in fluid communication with the interior of the barrel  62 . The end of the barrel  62  remote from the needle  64  may be provided with a radially extending flange  68  which is typically engaged by the fingers of an individual operating the syringe  60 . 
   The syringe  60  further includes a plunger  70  adapted for axial movement within the barrel  62 . The plunger  70  extends to a piston  72  which forms a fluid tight seal with the interior surface of the barrel  62 . The end of the plunger  70  remote from the piston  72  may be provided with a plate  74  which is typically engaged by the thumb of an individual operating the syringe  60 . 
   The syringe  60  differs from conventional syringes in that it is provided with a floating piston  80 . The floating piston  80  includes a body  82  formed from a spongy, resilient material. As will be apparent to those skilled in the art, it is necessary that the body  82  is formed from a material having sufficient resiliency to form a fluid tight seal with the interior wall of the barrel  62 . The floating piston  80  further includes a valve  84  which is formed from a substantially rigid material. Both the body  82  and the upper portion  44  are formed from materials which are impervious to attack by the fluids which are administered by the syringe  60 . 
   Referring to  FIGS. 9 and 10 , the body  82  of the floating piston  80  includes an upper portion  86  comprising a right circular cylinder and a lower portion  88  comprising a truncated cone. A passageway  90  extends entirely through the body  82  from the top to the bottom thereof. The passageway  90  may extend along the axis of the body  82  and may be circular in cross section, wherever, other locations and other cross sectional configurations of the passageway  90  may be utilized in the practice of the invention depending upon the requirements of particular applications thereof. 
   The valve  84  includes an imperforate top plate  92  which normally seals the upper end of the passageway  90  formed in the body  82 . The lower end of the valve  84  comprises a perforated plate  94  comprising a plurality of apertures  96  which facilitate fluid flow through the lower end of the passageway  90 . A rod  98  connects the imperforate top plate  92  to the perforated lower plate  94 . 
   Operation of the syringe  60  is illustrated in  FIGS. 7 and 8 . Referring first to  FIG. 7 , a first fluid to be administered is loaded into the portion of the barrel  62  of the syringe  60  situated below the floating piston  80 . A second fluid to be administered immediately following completion of the delivery of the first fluid is loaded into the portion of the barrel  62  of the syringe  60  situated above the floating piston  80 . The floating piston  80 , and particularly the body  82  thereof forms a fluid tight seal which maintains a separation between the two fluids. 
   The administration of the first fluid is accomplished by moving the plunger  70  inwardly, that is, from the position illustrated in  FIG. 7  toward the position illustrated in FIG.  8 . As the plunger  70  is moved inwardly, the floating piston  80  and the second fluid positioned within the barrel  62  of the syringe  60  between the floating piston  80  and the plunger  70  function to force the first fluid out of the barrel  62  through the hollow needle  64 .  FIG. 6  illustrates the floating piston  80  bottomed out in the barrel  62  of the syringe  60  with all of the first fluid having been delivered through the hollow needle  64 . 
   Further inward movement of the piston  72  compresses the material comprising the body  82  of the floating piston  80 . Due to the relative rigidity of the valve  84  as compared with the relative compressibility of the material comprising the body  82 , compression of the body  82  of the floating piston  80  under the action of the plunger  70  causes separation between the top of the passageway  90  formed through the body  82  of the floating piston  80  and the imperforate top plate  92  of the valve  84 . Such separation opens the passageway  90  through the body  82  thereby allowing the second fluid to flow through the body  82  of the floating piston  80  and through the needle  64  for administration to the patient. Inward movement of the plunger  70  continues until all of the fluid that was originally contained in the portion of the barrel  62  located between the plunger  70  and the floating piston  80  is dispensed. 
   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 component 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. 
   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.

Technology Classification (CPC): 0