Abstract:
A mixing syringe having a first sealed chamber containing a powder (powder housing) and a second sealed chamber containing a liquid (liquid housing). When the user needs to inject a patient, he or she holds the mixing syringe approximately upright and depresses a plunger. This motion causes a piercer to pierce a foil seal separating the two chambers. The liquid then drops down into the powder housing. The liquid flows through a passage in a piston located in the powder housing, where it then comes in contact with the powder itself. As the user continues pressing the plunger downward, the piercer comes to rest within the piston and seals the passage through the piston, thereby locking the piercer and piston together. The device is then ready for an injection. As the plunger is further depressed the piston expels the powder and liquid mixture through a needle.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     This invention relates to the field of medical devices. More specifically, the invention comprises a syringe which can mix a powder with a liquid carrier prior to injection into a patient.  
         [0003]     2. Description of the Related Art  
         [0004]     Syringes have long been used to inject liquid medicinal substances into the human body. Many such medicinal substances can be stored for extended periods in the syringe, ready for use. This is not true for all medicinal substances, however. A significant group of compounds must be stored in crystalline form. The crystalline form is difficult to introduce to the body, so a two step approach has been traditionally used.  
         [0005]     The crystalline substance is stored in a small bottle. A carrier liquid—which will be used to form a solution or colloid of the crystalline substance—is stored in a separate syringe. The bottle is provided with a soft cap. The syringe&#39;s needle can be inserted through this soft cap. The syringe is then used to inject the carrier liquid into the bottle.  
         [0006]     The bottle is then swirled to mix the crystalline substance into the carrier liquid. The syringe is then used to suck the liquid—now containing the crystalline substance—back out of the bottle. Once back in the syringe, the liquid can be injected into the patient in a conventional fashion.  
         [0007]     Medical personnel are familiar with this multi-step approach and generally perform the steps without a problem. Certain substances, however, are by their nature destined for use by untrained persons. One good example would be substances intended to treat hypoglycemia, particularly in diabetic persons.  
         [0008]     Glucogon is used to treat hypoglycemia. It is particularly effective for diabetics who are experiencing dangerously low blood sugar. An injection of Glucogon can remedy this serious problem. Unfortunately, Glucogon cannot be stored for long periods as a solution or colloid. It must instead be stored as a dry powder. Thus, the multi-step process described previously must be used to prepare and administer a Glucogon injection.  
         [0009]     Glucogon must generally be available for emergency use in insulin-dependent diabetics. It is used when the diabetic is showing signs of severe distress. Someone such as a family member must be prepared to give the injection, since time lost waiting for medical personnel or transportation to a hospital can be damaging, if not fatal. The reader will therefore appreciate that the person attempting to administer the Glucogon injection (1) probably has little experience with giving such injections, and (2) is likely to be under considerable emotional stress.  
         [0010]     The multi-step process found in the prior art often goes awry in these circumstances. The needle may be bent while trying to penetrate the bottle&#39;s cap. Other persons have injected the carrier liquid while omitting the mixing step altogether (which obviously does no good). Thus, a product which simplifies the process of mixing a powder medical product into a carrier liquid prior to injection would be quite helpful.  
       BRIEF SUMMARY OF THE INVENTION  
       [0011]     The present invention comprises a mixing syringe. The syringe has a first sealed chamber containing a powder (powder housing) and a second sealed chamber containing a liquid (liquid housing). When the user needs to inject a patient, he or she holds the mixing syringe approximately upright and depresses a plunger. This motion causes a piercer to pierce a foil seal separating the two chambers. The liquid then drops down into the powder housing. The liquid flows through a passage in a piston located in the powder housing, where it then comes in contact with the powder itself.  
         [0012]     As the user continues pressing the plunger downward, the piercer comes to rest within the piston and seals the passage through the piston, thereby locking the piercer and piston together. The syringe is then optionally agitated to promote thorough mixing of the powder and liquid. The device is then ready for an injection. As the plunger is further depressed, the piston expels the powder and liquid mixture through a needle. 
     
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0013]      FIG. 1  is an exploded perspective view with a cutaway, showing all the components of the present invention.  
         [0014]      FIG. 1B  is a detailed perspective view, showing the secondary piston.  
         [0015]      FIG. 1C  is a detailed perspective view, showing the primary piston.  
         [0016]      FIG. 2  is a sectional elevation view, showing the powder housing.  
         [0017]      FIG. 3  is a perspective view, showing the powder housing.  
         [0018]      FIG. 4  is a sectional elevation view, showing the liquid housing.  
         [0019]      FIG. 5  is a perspective view, showing the liquid housing.  
         [0020]      FIG. 6  is a perspective view, showing the liquid and powder housings united.  
         [0021]      FIG. 7  is a perspective view, showing the use of a linking clip to lock the liquid and powder housings together.  
         [0022]      FIG. 8  is a sectional elevation view, showing the operation of the invention.  
         [0023]      FIG. 9  is a detailed perspective view with a cutaway, showing the operation of the invention.  
         [0024]      FIG. 10  is a sectional elevation view, showing the operation of the invention.  
         [0025]      FIG. 11  is a sectional elevation view, showing the operation of the invention. 
     
    
     REFERENCE NUMERALS IN THE DRAWINGS  
       [0026]    
       
         
               
               
               
               
             
           
               
                   
               
               
                   
               
             
             
               
                 10 
                 mixing syringe 
                 12 
                 needle 
               
               
                 14 
                 needle anchor 
                 16 
                 powder housing 
               
               
                 18 
                 liquid housing 
                 20 
                 primary piston 
               
               
                 22 
                 flange 
                 24 
                 flange 
               
               
                 26 
                 foil seal 
                 28 
                 foil seal 
               
               
                 30 
                 linking clip 
                 32 
                 flange 
               
               
                 34 
                 retaining clip 
                 36 
                 bore 
               
               
                 38 
                 bore 
                 40 
                 vent block 
               
               
                 42 
                 piercer 
                 44 
                 secondary piston 
               
               
                 46 
                 vent 
                 48 
                 piercer rod 
               
               
                 50 
                 plunger head 
                 52 
                 plunger rod 
               
               
                 54 
                 piercer seat 
                 56 
                 powder 
               
               
                 58 
                 needle inlet 
                 60 
                 powder assembly 
               
               
                 62 
                 needle cap 
                 64 
                 liquid assembly 
               
               
                 66 
                 liquid 
                 68 
                 passage 
               
               
                 70 
                 mixing chamber 
                 72 
                 escaping air 
               
               
                 74 
                 mixture 
                 76 
                 plunger 
               
               
                   
               
             
          
         
       
     
       DETAILED DESCRIPTION OF THE INVENTION  
       [0027]      FIG. 1  shows all the invention&#39;s components in an exploded view. Needle  12  is attached to powder housing  16  at needle anchor  14 . The lower portion of the powder housing is fluidly connected with the needle&#39;s hollow interior (Throughout this disclosure, directional terms such as “upper” and “lower” will be understood to refer only to the orientations of objects shown in the views, and should not be construed as limitations on the scope of the invention). Bore  38  runs through the center of powder housing  16 . Primary piston  20  can slide downward within bore  38 , though it is ordinarily held in place by friction and does not move freely.  
         [0028]     The upper end of the powder housing  16  is open. Flange  22  surrounds this opening. The opening is ordinarily covered by some type of seal. In the embodiment shown, foil seal  26  is glued to the upper surface of flange  22  in order to seal the opening. The particular construction of the seal is unimportant, so long as it can be pierced (the significance of which will be explained subsequently).  
         [0029]     Liquid housing  18  is located above powder housing  16 . Bore  36  passes completely through the liquid housing, meaning that both ends of the liquid housing are open. Flange  24  is located on the open lower end of the liquid housing. The lower opening is sealed by gluing foil seal  28  to flange  24 .  
         [0030]     In assembling the device for use, flange  24  is pressed against flange  22 . Linking clip  30  can then be locked over the two flanges to mate liquid housing  18  to powder housing  16 . The linking clip is preferably made of a resilient material so that it can “snap” into place. It thereby holds the two housings firmly together.  
         [0031]     Plunger  76  is designed to slide into bore  36 . Secondary piston  44  slides tightly within the bore. Piercer  42  is a conical surface located well below the secondary piston. Piercer rod  48  locates piercer  42  with respect to secondary piston  44 . Plunger head  50  is connected to secondary piston  44  by plunger rod  52 . The user actually presses on the plunger head to actuate the device.  
         [0032]     Once the plunger is installed within bore  36 , it may be desirable to prevent its accidental removal (which may inadvertently release the contents of the liquid housing). Retaining clip  34  is provided to prevent the plunger&#39;s removal. It slides over flange  32  and locks into place. The reader will observe that the retaining clip features a center hole which is large enough to allow the passage of plunger rod  52  but not large enough to allow the passage of secondary piston  44 . Thus, with the plunger installed and the retaining clip in position, the user cannot pull the plunger out of the liquid housing.  
         [0033]      FIGS. 1B and 1C  shows certain features in more detail.  FIG. 1B  shows how the upper portion of bore  36  incorporates a pair of vent blocks  40 . The reader will observe that secondary piston  44  incorporates a pair of corresponding vents  46 . When the secondary piston is near the top of bore  36 , the two vent blocks  40  seal the two vents  46 . Thus, when the user presses the plunger downward into the bore, air within the liquid housing cannot escape past the secondary piston. The air must be compressed by the piston. However, once secondary piston  44  has moved downward enough to clear the two vent blocks  40 , air can pass through the two vents  46 . The operational significance of these features will be explained subsequently.  
         [0034]      FIG. 1C  shows how piercer  42  interacts with primary piston  20 . Primary piston  20  includes a passage  68  which opens into piercer seat  54 . Piercer  42  has a male conical shape whereas piercer seat  54  has a female conical shape. Those skilled in the art will realize that if the piercer is pushed against the primary piston, the piercer will seal against the piercer seat, thereby closing passage  68 . If the plunger is then depressed further, the piercer will push the primary piston downward.  
         [0035]      FIG. 2  is a sectional elevation view through the powder housing, showing it ready for assembly into a completed syringe. Some explanation of how this component might be manufactured is helpful. The needle is attached to the empty powder housing prior to the addition of any other components. The housing is then oriented upright as shown. Foil seal  26  and primary piston  20  are not yet present. Powder  56  is introduced through the open top and allowed to settle in the bottom. Primary piston  20  is then pushed downward to the position shown, where it will be retained by friction. The area below the primary piston is designated as mixing chamber  70 . In this view, the reader can easily perceive the shape of piercer seat  54  and passage  68  in primary piston  20 .  
         [0036]     Once all the items are placed within the powder housing, the upper opening is sealed by the addition of foil seal  26 .  FIG. 3  shows the completed powder assembly  60 , with foil seal  26  in place. Those skilled in the art will know that many materials could be substituted for the foil seal, such as a thin plastic membrane. Needle cap  62  is shown snapped over the needle in the view. This protects the needle and also protects the user from inadvertent injury. The needle cap is, of course, removed prior to using the syringe.  
         [0037]      FIG. 4  shows an elevation view through liquid assembly  64 . A brief understanding of its manufacturing process may also be helpful. Foil seal  28  is placed over the open lower end of liquid housing  18 . A desired volume of liquid  66  is then introduce through its open upper end. Next, plunger  76  is inserted through the open upper end, with secondary piston  44  sealing off the open upper end.  
         [0038]     Referring now to  FIG. 5 , retaining clip  34  can then be locked over flange  32  to retain the plunger within the liquid housing. Liquid assembly  64  is thereby complete. The reader will appreciate that the powder assembly and the liquid assembly can be manufactured on different production lines. They could even be made in completely separate facilities. They need only be united just prior to use.  
         [0039]     In  FIG. 6 , liquid assembly  64  has been placed over powder assembly  60 , with the two foil seals touching. Linking clip  30  is then locked over flange  22  and flange  24 . The linking clip is preferably made of a resilient polymer, sot that once it snaps into place it will hold the liquid and powder assemblies firmly together.  FIG. 7  shows the completed mixing syringe  10 , with linking clip  30  in position.  
         [0040]     Those skilled in the art will know that the two assemblies could be joined using many different techniques. They could, for instance, be glued together. A threaded connection between the two could also be provided. Thus, the linking clip should be understood as being only one example.  
         [0041]     Once in the state shown in  FIG. 7 , the mixing syringe is ready for use.  FIGS. 8 through 11  illustrate the operation of the device. The user must first hold the syringe approximately upright, as shown in  FIG. 8 . He or she then presses down on plunger head  50 . The reader will recall that at this point vent blocks  40  are occluding vents  46  in secondary piston  44 . Thus, the secondary piston pressurizes the gas lying beneath it (and lying on top of the water within the liquid housing). The gas is moderately compressed by the time piercer  42  ruptures foil seal  26  and foil seal  28 .  
         [0042]     Once the foil seals are ruptured, the liquid within the liquid housing shoots down (under pressure) into powder housing  16 . The liquid flows down through primary piston  20  and into mixing chamber  70 , where it mixes with the powder. As the user continues depressing the plunger head, vents  46  slide down past vent blocks  40 . The compressed air is then able to slide past the secondary piston at a metered rate.  
         [0043]      FIG. 9  shows the secondary piston just as it has traveled past the vent blocks. A cutaway through the liquid housing and the plunger is provided to aid visualization. As the secondary piston is propelled downward, escaping air  72 .passes through vents  46 . The size of the vents limits the rate at which the user can depress the plunger. In effect, the vent sizing meters the downward rate of travel for the plunger. This is a desired feature, since it allows time for an appropriate amount of liquid to spray downward past primary piston  20 .  
         [0044]     The user continues depressing the plunger until piercer  42  makes contact with piercer seat  54 —as shown in  FIG. 10 . The user will feel a resistance at this point and should stop depressing the plunger. The liquid and powder housings are preferably made of transparent material so that the user can actually see the piercer seat within the primary piston.  
         [0045]     At this point the volume beneath primary piston  20  will be filled with liquid and powder. An additional amount of liquid  66  is often left above primary piston  20 . This is true because an excess amount of liquid is preferably employed to ensure complete or near-complete filling of the volume beneath the primary piston.  
         [0046]     At this point the fairly violent injection of the liquid into the powder will have frequently produced a good mixture. However, it is advantageous for the user to swirl or shake the syringe to mix any remaining solid clumps. The syringe is then ready for injection.  
         [0047]     If the needle cap has not already been removed, it is removed at this point. The volume to be injected is now completely sealed beneath piercer  42  and primary piston  20  (the piercer has sealed the passage through the primary piston). The syringe can be inverted at this point (or placed in any desired orientation). If the plunger is depressed further—as shown in  FIG. 11 —piercer  42  drives primary piston  20  toward the needle, thereby forcing mixture  74  out through the needle. The user can invert the syringe and force a few drops out through the needle to ensure purging of any air within the mixture. The needle is then inserted into the patient at an appropriate point and the mixture is injected.  
         [0048]     The reader will thereby appreciate that the present invention can automate the mixing of a powder into a carrier liquid prior to injection into a patient. The device functions well even after an extended period of storage. This is true because the liquid and the powder are housed in completely separate containers. Even though the containers may be stacked in line, they are still separate. No water will seep into the powder housing, thereby potentially contaminating the powder.  
         [0049]     Nor will the orientation of the device during storage affect its utility. Returning to  FIG. 2 , the reader will recall that powder  56  is initially stored within mixing chamber  70 . If the powder housing is inverted (with respect to the position shown in the view), some of the powder may flow through passage  68  and wind up on the opposite side of primary piston  20 . This fact will not significantly alter the device&#39;s operation. Returning now to  FIG. 8 , the reader will recall that at the point the foil seals are ruptured, the gas residing above the liquid in the liquid housing has been compressed by the secondary piston&#39;s downward travel. When the seals rupture, the liquid is propelled violently down into the powder housing. It swirls around and washes any powder above the primary piston down into the mixing chamber.  
         [0050]     This process is not perfect, and a small amount of powder may ultimately remain above the mixing chamber. The vast majority will be mixed, however, and any lost powder will not be significant.  
         [0051]     The embodiment shown up through  FIG. 11  places the liquid housing above the powder housing during the mixing process. While this represents the preferred embodiment, it is obviously not the only possible arrangement.  FIG. 12  shows an alternate embodiment in which powder housing  16  is placed above liquid housing  18 . When the piercer pierces the foil seal, the powder is propelled downward into the liquid housing. The user must generally shake the syringe to ensure that all the powder passes through the primary piston and down to liquid  66 . The plunger is depressed until the piercer seals the primary piston. The syringe is then swirled and the mixture is injected.  
         [0052]     Although the preceding description contains significant detail, it should not be construed as limiting the scope of the invention but rather as providing illustrations of the preferred embodiments of the invention. Thus, the scope of the invention should be fixed by the following claims, rather than by the examples given, with the understanding that a single device could incorporate several emitters or detectors.