Abstract:
A dual chamber syringe ( 10 ) comprises an inner cylindrical body ( 30 ) having a open end, a closed end with an inner discharge outlet ( 35 ) formed therein, and an inner plunger ( 91 ) sealingly slideable within the inner body, and an outer cylindrical body ( 11 ) enclosing the inner cylindrical body and having an open end, a closed end with an outer discharge outlet ( 20 ) formed therein, and an outer plunger ( 75 ) sealingly slidable between the outer body and the inner body, the inner discharge outlet extending into the outer discharge outlet such that the inner body is in fluid communication through the outer discharge outlet with the exterior of the inner and outer body.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a dual chamber syringe for the injection of contrast media by an injector. 
       BACKGROUND OF THE INVENTION 
       [0002]    Syringes are typically used in medical applications to hold fluids for injection into patients. In some applications such as medical imaging using contrast media, the syringe is engaged to a power injector for driving the syringe plunger to inject fluid at a desired flow rate and/or pressure as needed for the medical procedure. 
         [0003]    Frequently multiple liquids must be injected in a procedure, such as in a CT, Angiography, Ultrasound or other medical imaging procedure where injection of contrast media for medical imaging is followed and/or preceded by injection of saline solution. Similar multiple liquid injections may also appear in nuclear medicine or other applications. 
         [0004]    For such applications, frequently the art has utilized a dual-head injector, having two syringes and two injector drives for driving the respective plungers in each of the dual syringes. This approach, however, raises various difficulties, such as added complexity of managing dual syringes and purging air from connecting tubing extending between the two syringes. 
         [0005]    The art includes various proposals for single syringes including multiple chambers, permitting selective injection of two liquids from the single syringe. However, these various proposals are not readily used in a flexible way as is needed for a typical imaging procedure. For example, many dual-chamber syringes utilize chambers separated along the length of the syringe by a plunger or other divider. Such syringes have the drawback that the two fluids in the syringe may not be selectively injected or mixed in a controllable fashion, since one fluid must flow through the chamber containing the other fluid to reach the patient. 
         [0006]    There have been proposals in the art for dual-chamber syringes in which the two chambers are coaxially positioned; that is, the second chamber annularly surrounds the first chamber. This structure has the advantage that the movement and flow of the fluid from the chambers may be independently injected. However, in these known structures, the outer and inner chambers have a connecting point within the body of the syringe, which raises the same difficulties noted in the preceding paragraph, namely, fluids may not be selectively injected or mixed, since there will always be mixing of fluids at the connection point of the chambers. Hence, the present invention allows fluids to be selectively, and independently, injected into a subject or mixed outside of the syringe chambers prior to injection. 
       SUMMARY OF THE INVENTION 
       [0007]    The present invention is directed to a dual chamber syringe that avoids these difficulties of the prior art, which comprises an inner cylindrical body having a open end, a closed end with an inner discharge outlet formed therein, and an inner plunger sealingly slideable within the inner body, and an outer cylindrical body enclosing the inner cylindrical body and having an open end, a closed end with an outer discharge outlet formed therein, and an outer plunger sealingly slidable between the outer body and the inner body, the inner discharge outlet extending into the outer discharge outlet such that the inner body is in fluid communication through the outer discharge outlet with the exterior of the inner and outer body. 
         [0008]    In specific embodiments of the syringe, the syringe includes a backer plate mounted between the open rearward end of the inner and outer bodies to maintain a spacing therebetween. A ram (or pushrod) extends from the inner plunger through the open end of the inner body outside the inner body, and a ram (or pushrod) extends from the outer plunger through an aperture in the backer plate outside the outer body, thus permitting selective movement of the inner and outer plungers for an injection. 
         [0009]    An injector for use with the syringe described above includes first and second motorized drives, the first drive engaging to the ram coupled to the inner plunger and the second drive coupled to the ram coupled to the outer plunger, the drives independently driving the inner and outer plungers for injection of fluid. 
         [0010]    These and other objectives of the present invention will be more readily apparent from the following detailed description of the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with a general description of the invention given above, and the detailed description of the embodiments given below, serve to explain the principles of the invention. 
           [0012]      FIG. 1A  is a partial schematic longitudinal section of one embodiment the dual chamber syringe and tip cap. 
           [0013]      FIG. 1B  is a schematic longitudinal section of the front end of another embodiment of the dual chamber syringe. 
           [0014]      FIG. 1C  is a schematic longitudinal section of the front end of an additional embodiment of the dual chamber syringe with internal threads in the nozzle. 
           [0015]      FIG. 1D  is a schematic longitudinal section of the front end of the dual chamber syringe and an adapter. 
           [0016]      FIG. 1E  is a schematic longitudinal section of the front end of the dual chamber syringe with an adapter secured to the nozzle. 
           [0017]      FIG. 1F  is a perspective view of a backplate with gripping edges engaged with syringe. 
           [0018]      FIG. 1G  is a partial schematic longitudinal section of an alternative embodiment of the dual chamber syringe and tip cap. 
           [0019]      FIG. 2  is a perspective view of rear section of backplate. 
           [0020]      FIG. 3  is a perspective view of dual chamber syringe. 
           [0021]      FIG. 3A  is a perspective view of the alternative embodiment of the dual chamber syringe of  FIG. 1G . 
           [0022]      FIG. 4  is a view showing pushrods and drive mechanism. 
           [0023]      FIG. 4A  is a view showing pushrods and drive mechanism used with the alternative embodiment of the dual chamber syringe of  FIG. 1G . 
           [0024]      FIG. 5  is a view of a manually operated pushrod device. 
           [0025]      FIG. 5A  is a view of a manually operated pushrod device used with the alternative embodiment of the dual chamber syringe of  FIG. 1G . 
           [0026]      FIG. 6  is a view showing an alternative embodiment of pushrods and drive mechanism. 
           [0027]      FIG. 7A  is a longitudinal section of an outer piston of the alternative embodiment of the dual chamber syringe of  FIG. 1G . 
           [0028]      FIG. 7B  is a perspective view of an outer piston of the alternative embodiment of the dual chamber syringe of  FIG. 1G . 
           [0029]      FIG. 7C  is a perspective view of the engagement of the pistons of the alternative embodiment of the dual chamber syringe of  FIG. 1G  to the pushrods of  FIG. 4A . 
           [0030]      FIG. 7D  is a perspective view showing the rotation of the alternative embodiment of the dual chamber syringe of  FIG. 1G  to engage its pistons to the pushrods of  FIG. 4A . 
           [0031]      FIG. 7E  is a perspective view showing the rotation of the pushrods of  FIG. 4A  to engage the pistons of the alternative embodiment of the dual chamber syringe of  FIG. 1G . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0032]    As noted in the Background section, there is a need for a dual chamber syringe, which allows fluids to be selectively, and independently, injected into a patient, or mixed outside of the syringe chambers prior to injection. As shown in  FIGS. 1A and 3 , the dual chamber syringe  10  of the invention has an outer body  11  whose inner side or wall  14  provides the outer circumferential wall of the outer chamber  15 . The syringe  10  has a nozzle  20  extending from the apex of the conical cone shaped forward end or nozzle end  25  of the outer body  11 . 
         [0033]    Positioned inside the outer body  11  is an inner body  30 . The outer wall  31  of the inner body  30  provides the inner circumferential wall of the outer chamber  15  and its inner wall  33  circumferentially encloses the inner chamber  32 . The forward end  40  of the inner body  30  has a conical section  27  and a nozzle  35  extending outward from the apex of the conical or cone section  27  of the inner body  30 . The inner body  30  has four evenly spaced projection or tabs  45   a - d , as shown in  FIG. 3 , circumferentially extending from the base portion  29  of the conical section  27  that extends from the body  30  and provides a forward chamber  50  that is continuous with the outer chamber  15 ,  FIG. 1A . The projections  45   a - d  are bonded to the inner surface  16  of the cone shaped forward end  25  of the outer body  11  by methods known to one skilled in the art such as ultra-sound bonding, laser bonding, etc. The nozzle  35  of the inner body  30  is of a size that is insertable into the opening  55  of nozzle  20  of the outer body  11 . The diameter of the nozzle  35  is small enough that a first passageway  60  is provided between the outer surface of nozzle  35  of the inner body  30  and inner surface  21  of nozzle  20  that permits the flow of fluid from the outer chamber  15 . Nozzle  35  has a second passageway or opening  56  that permits the outflow of fluid from the inner chamber  32 . 
         [0034]    A tip cap  120   a  may be inserted over nozzles  20  and  35 . As shown in  FIG. 1A , the cap  120   a  may have a circular recess or slot  121   a  into which nozzle  20  is inserted and cylindrical recessed bore or cavern  122   a  into which nozzle  35  is inserted. 
         [0035]    In another embodiment as shown in  FIG. 1B , there is a cylindrical protrusion  19  that extends from the conical forward end  25  that encircles the outer nozzle  20 . The tip cap  120   b  has a circular recess or slot  121   b  into which protrusion  19  is inserted and a cylindrical barrel shaped recess  122   b  into which both the inner nozzle  35  and outer nozzle  20  are inserted. In the embodiment shown in  FIG. 1C , the inner surface of protrusion  19   c  may also have threads  23 . The top cap  120   c  has circular recess or slot  121   c  and cylindrical recessed bore or cavern  122   c  to engage with the protrusion  19  and nozzles  11  and  35  as described for  FIG. 1B . The slot  121   c  may include threads that mate with threads  23  or may be unthreaded and fit by interference over outer nozzle  20 . The syringe tip  20  of all embodiments of the invention meets the leur taper specifications as set forth in the ISO standard. 
         [0036]    In other embodiments, the nozzle  20  may optionally have one or more external threads  24  as shown in  FIGS. 1A and 1D  or internal threads  23  as shown in  FIG. 1C . The external threads  24  can engage female Luer locks and the internal threads  23  may engage threads of a male Luer lock (Luer locks not shown). The Luer locks are part of a fluid line connected to a patient for injection of fluids. The syringe  10   b  shown in  FIG. 1D  is an enlarged perspective of the syringe  10  in  FIG. 1A . Also shown in  FIG. 1D  is an adapter  125 , which can connect to syringe  10   b  as shown in  FIG. 1E . The adapter  125  allows for the connection of a large syringe tip, which does not meet ISO standards, to a small female Luer lock, which complies with ISO standards. The adapter  125  is made of a hard plastic, and has internal threads  126  in a cylindrical extension on one end thereof, which engage the external threads  24  of nozzle  20 . The adapter  125  also has internal threads  23   a  inside a cylindrical extension on its second end, and a male Luer connector tip or nozzle end  36   a , which enables the syringe  10   b  to connect to a female Luer lock. The cylindrical extensions and Luer connectors are coaxial. As shown in  FIG. 1E , when the adapter  125  is connected to the nozzle  20  the first passageway  60  opens into third passageway  129 , which is formed upon making the connection of adapter  125  and nozzle  20 . The second passageway  56  opens into fourth passageway or opening  57  of the adapter  125 . These connecting passageways or openings allow fluid to flow from the outer chamber  15  and the inner chamber  32  to the Luer lock connection through the fourth passageway  57  of the adapter  125 . 
         [0037]    The rearward edge  65  of the outer body  11  has a flange  66  extending radially outward,  FIG. 1A . The flange  66  adapts to the circumferential recess  67  formed by a tapered ridge  68 , or knurl, on the forward surface  69  of the backer plate  70 ,  70   a . In an alternative embodiment as shown in  FIG. 1F , the backer plate  70  assembly has two griping edges  74   a ,  74   b , which secure flange  67  of the outer body  11 . 
         [0038]    Referring to  FIG. 3 , the backer plate assembly  70  has two semi-lunate, i.e., crescent-shaped, openings  71   a ,  71   b  opposite of each other and positioned a certain distance from a circular opening or aperture  72  as defined by the thickness of the inner girdle or inner circular ring  115 . The aperture  72  is formed by the inner surface of inner circular ring  115 . The circular ring  115  is integrally connected to the outer disc  74  by bridge members  73   a ,  73   b . Welding, adhesion or other means known to one skilled in the art bonds the inner ring  115  of the backer plate  70 ,  70   a  and the end  57  of the inner barrel  30 . The outer disc  74  of the backer plate  70 ,  70   a  and the flange  66  of the outer barrel  11  are also bonded keeping the inner and outer barrels in a coaxial position. Additionally, the backer plate syringe assembly  130 ,  FIGS. 1A and 1F , prevents the inner barrel from coming off the outer barrel when the inner rubber plunger tip  30  is pulled back. 
         [0039]    Inside the outer chamber is a slidable toroidally shaped rubber piston  75  that is in contact with the surface of the inner wall  14  of the outer body  11  and contacts the surface of the outer wall  31  of the inner body  30 . When the syringe  10  is mounted on the drive mechanism  105 , the pushrod  76  engages the rubber piston  75  by inserting at least two or more hooks or locking projections  79   a, b  into corresponding slots for engagement on the rear wall  80  of the rubber piston  75  to secure the pushrod  76  to piston  75 . Additionally, the cylindrical extension  93  of the inner chamber pushrod  81  has two or more locking type projections  90  on the surface of the cylindrial extension  93  of pushrod  81  that engage corresponding slots in the inner wall  96  of the recess  94  to secure the pushrod  81  with piston  91 . In another embodiment the wall  97  of cylindrical extension  93  has threads that engage threads on the wall of recess  94  of piston  91  (threads not shown) to form, a screw lock mechanism may be used to secure the rod  81  to piston  91 . 
         [0040]    Referring to  FIGS. 1G ,  3 A,  7 A and  7 B, in an alternative embodiment of the dual chamber syringe shown in the preceding Figs., an alternative outer piston is formed of a rubber cover  75 ′ over a hard plastic core  80 ′ forming the rear surface of the outer piston. Integrally formed in the hard plastic backer plate/rear surface  80 ′ are hooks  77  for engaging hooks or locking projections  79   a ′ and  79   b ′ on the front surface of outer pushrod  76 ′. Further, an alternative inner piston is formed of a rubber cover  91 ′ over a hard plastic backer plate  99 . Backer plate  99  is engaged to threads or other engagement features on the interior of a recess  94 ′ in the rear side of rubber cover  91 ′. Backer plate  99  includes hooks  92  for engaging a t-shaped hook  90 ′ at the outer end of the inner pushrod  81 ′. Other features of the embodiment of  FIG. 1G  are similar to those previously described and like reference numerals have been used for like features thereon. 
         [0041]      FIG. 7C  illustrates the engagement of the hooks  77  on backer plate  80 ′ and hooks  92  on backer plate  99  to the hooks  79   a ′ and  79   b ′ and t-shaped hook on pushrod  81 ′. Specifically, hooks  77  couple into hooks  79   a ′ and  79   b ′ and hooks  92  couple to t-shaped hook  90 ′ when the syringe  10  and pushrods  76 ′ and  81 ′ are relatively oriented as shown in  FIG. 7C . In one embodiment, illustrated in  FIG. 7D , syringe  10  is installed rotated 90 degrees from the position shown in  FIG. 7C  and then is rotated as shown by the arrow in  FIG. 7D  to an engaged position as shown in  FIG. 7C . In an alternate embodiment, illustrated in  FIG. 7E , pushrods  76 ′ and  81 ′ are rotated 90 degrees from the position shown in  FIG. 7C  and the syringe is installed while the pushrods  76 ′ and  81 ′ are in this position, and once the syringe is installed, pushrods  76 ′ and  81 ′ are rotated as shown by the arrow in  FIG. 7E  to an engaged position as shown in  FIG. 7C . 
         [0042]    Referring to  FIGS. 1A and 3 , inside the inner chamber is a valve assembly  46  comprised of a one-way valve  47  (not shown in  FIG. 1A ), commonly known as a duckbill valve and a valve plate  48  to fix valve  47  in the appropriate position. The valve plate  48  is bonded at a position in the conical section  27  as seen in  FIG. 1A . 
         [0043]    The outer chamber pushrod  76  of the coaxial plunger system  100  is a hollow cylinder having a diameter large enough to allow the insertion, passage, and sliding movement of the inner chamber pushrod  81 . Pushrod  76  has two opposed longitudinal slots  82   a ,  82   b  along its cylindrical wall  83  that extend along its length from its forward section rearward and terminating a distance from its rear section. The slots  82   a ,  82   b  bifurcate the pushrod  76  such that its two halves pass through the apertures  71   a ,  71   b  in the backer plate  70 . In the drive mechanism  105  of  FIG. 4 , pushrod  76  has a track of teeth  77  that extend a length along the rear portion of the rod  76 . The teeth  77  engage the gear mechanism  78  of the injector drive  110  to move the pushrod  76  to slide the piston  75  forward or rearward. The pushrod  76  and piston  75  are engaged as previously described. The pushrods  76  and  81  may also be operated by other driving means as known to one skilled in the art. 
         [0044]    The inner chamber pushrod  81  of the coaxial plunger system  100  is cylindrical with a diameter small enough to be inserted and have slidable movement within the outer chamber pushrod  76 . The pushrod  81  has cylindrical extension  93  with a flat surface extending from its forward end. A rubber piston  91  which is slidably moveable within the inner chamber  32  engages the extension  93  of the pushrod  81  by means of a recess  94  in its rearward end as previously described. A track of teeth  95  extends a length along the rearward end of pushrod  81 . The teeth  95  engage a gear mechanism  98  of the injector drive  112  to slide the pushrod  81  forward or rearward. 
         [0045]    The gears  78  and  98  of the injector drives  110  and  112  are independently controlled. The speed of movement of the pushrods  90  and  76  may be different depending upon the injection conditions that need to be maintained. In one embodiment, the drive mechanism  105  has locking projections  86   a ,  86   b , which engage the backer plate assembly  130 ,  130   a , as the syringe  10  is joined to the drive mechanism  105  in a twisting or rotating motion. 
         [0046]      FIG. 4A  illustrates the use of an alternative inner pushrod  81 ′ and outer pushrod  76 ′ with the embodiment of an injector that is otherwise similar to that shown in  FIG. 4 . 
         [0047]      FIG. 6  illustrates an alternative embodiment of driving pushrods which may be used with any embodiment of the pushrods shown herein. In this embodiment the injector drives  110 ′ and  112 ′ are coupled to screw shafts  114  and  116  respectively. Followers  115  and  117  are threadedly engaged on screw shafts  114  and  116  and coupled to pushrods  76 ′ and  81 ′ respectively. In this embodiment, rotation of drives  110 ′ and  112 ′ causes rotation of screw shafts  114  and  116  and translation of followers  115  and  117  along with pushrods  76 ′ and  81 ′. 
         [0048]    The dual chamber syringe  10  is disposable, and includes walls that will withstand only moderate or low pressure. A pressure jacket is not required in use of this dual chamber syringe assembly. The body of both inner  30  and outer chambers  11  withstand high pressure independently (usually up to about 350 psi pressure). Generally, a contrast media (high viscosity) that requires high pressure is filled in the inner syringe and a saline that requires low pressure is filled in the outer chamber. The pressure resistance of the outer body  11  or barrel is lower than that of the inner body  30  or barrel because the diameter is larger on the same material and thickness. The wall  33  of the inner chamber  32  withstands both expansion and compression pressure. The wall thicknesses of both the inner body  30  and outer body  11  may vary and would be chosen according to the medical solution used and operating pressure, as well as syringe size. As illustrated, the volume of the inner and outer chambers would be approximately 100 ml each, but other volumes are possible; e.g., 50 ml or 200 ml for each chamber. 
         [0049]    The syringe  10  may be prefilled with fluids at the factory, or may be filled at a medical services delivery location. Factory pre-filling may fill the syringe inner and outer chambers to various volumes, as desired for a particular medical application. Factory prefilling may be performed with outer and inner bodies  11  and  30  assembled together without pistons  91  and  75 , and sealed at their nozzles  20  and  35  by a tip cap. In this procedure, inner body  30  is held in place by a filling tool, and the cavity between inner body  30  and outer body  11  is filled and then plunger  75  is inserted into the cavity. Then inner body  30  is filled and plunger  91  is inserted into inner body  30 . Thereafter plungers  75  and  91  are inserted and the backer plate  70  is fixed on the end  57  of inner barrel and flange  66  of outer barrel and the pre-filled syringe is completed. It will be appreciated that the embodiment of the invention shown in  FIG. 3A  may be assembled empty, and subsequently pre-filled using a filling tool having pushrods similar to those shown in  FIG. 3A , to withdraw the plungers  75 ′ and  91 ′ to draw fluid through the nozzle  20  into each of the two chambers. Alternately, the embodiment of the invention shown in  FIG. 3A  may be sold empty and filled at the patient bedside prior to an injection operation. 
         [0050]    The dual chamber syringe may be used to administer fluid agents comprising diagnostic agents (e.g., X-ray, magnetic resonance, optical, etc. agents), therapeutic agents, saline and combinations thereof. Both syringes may have the same agent or each chamber may have different agents than the other. Such combinations are, and not limited to, two diagnostic agents, a diagnostic/therapeutic combination, two therapeutic agents, a diagnostic/saline combination and a therapeutic/saline combination. The agents may be injected from each chamber in a sequential manner, that is, first one agent is injected from one chamber then the other agent is injected from the other chamber. The agents may also be injected from the chambers in an alternate or interchangeable manner, that is, a first amount of one agent from one chamber is injected and then a second amount of another agent from the other chamber is injected. This process is repeated as necessary. The agents may also be injected from the chambers simultaneously, that is, the agents are injected at the same time. The rates of injection from both chambers may be independently varied depending upon the diagnostic or therapeutic procedure used in the subjects as known to one skilled in the art. The injector mechanism may be the drive mechanism as previously described and adapted to a power injector, manually operated devices that have inner and outer pushrods to move the pistons of the dual chamber syringe, or any other device that is capable of moving the pistons to inject fluids into a subject or patient. 
         [0051]    An example of a manually operated pushrod device is shown in  FIG. 5 . There is an inner pushrod  81  that is within an outer pushrod  76 , both pushrods engage pistons  91  and  75  as previously described for the same described for  FIG. 4 . At the end of pushrod  76  and pushrod  81 , there are extensions  108 ,  109  that allow the user to manually move the pushrods in the syringe  10 . The shape of the extensions  108 ,  109 , may be circular, rectangular, have opposing straight and curved edges or other shapes as known to one skilled in the art to allow the user to move the pushrods  76 ,  81 , within the dual chamber syringe  10 . 
         [0052]      FIG. 5A  illustrates the use of an alternative inner pushrod  81 ′ and outer pushrod  76 ′ with the embodiment of a manually operated pushrod device that is otherwise similar to that shown in  FIG. 5 . 
         [0053]    While the present invention has been illustrated by the description of an exemplary embodiment thereof, and while the embodiment has been described in considerable detail, it is not intended to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and methods and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the scope or spirit of Applicants&#39; general inventive concept.