Abstract:
Disclosed is a medical injection assembly in which the assembly is adapted to reduce the risk of accidental injection of a patient and prevent cross contamination of patients or injectors.

Description:
CROSS REFERENCE OF RELATED APPLICATIONS 
     This application claims priority to, and benefit from, U.S. patent application Ser. Nos. 09/685,499, filed 10 Oct. 2000; 09/685,633, filed 10 Oct. 2000; and Russian Patent Application No. 99124268, filed 23 Nov. 1999, which is now Russian Patent No. 2152228; the disclosures of which are entirely incorporated by reference herein to the extent permissible by law. 
     TECHNICAL FIELD OF THE INVENTION 
     The invention relates to a medical injection assembly in which the assembly is adapted to reduce the risk of accidental injection of a patient. 
     BACKGROUND OF THE INVENTION 
     The most effective measure to prevent many diseases is the mass immunization with vaccines. Since medical science has come to understand the principles of viral theory and its importance to the transmission of diseases, the need to break the viral or bacterial transmission chain from host to host has become well-established. There are wide varieties of methodologies accepted by medical science to break the chain depending on the requirements of the situation. The most stringent protocols include: sterilization, disinfection, and sanitization utilizing heat chemicals and/or ionizing radiation. 
     Barriers are another common protocol and can be as simple as establishing an imaginary boundary where one side of the boundary is kept clean and the other is defined as contaminated. Any object being transferred from the clean to the contaminated side of the boundary is not returned to the clean side without being disinfected, sanitized, or sterilized. A typical example of this type of protocol is within the medical surgical fields. The surface of the operating table is defined as the boundary. Any item that is dropped below the surface of the operating table is immediately defined as contaminated. This includes surgical implements or the surgeon&#39;s hands. 
     With needle injection devices there are two common protocols both of which start from the premise that a used syringe is, by definition, contaminated. The first, which is commonly used in dentistry, uses syringes and sometimes needles that are sterilized after each use. The second is more commonly used in general medicine in the U.S. and other developed countries. This is the disposable syringe and needle assembly. Because of the low cost of production typically—less than $0.10 per syringe assembly—this protocol is well-accepted. 
     Jet injector systems on the other hand continue to be characterized by relatively high cost per injection ($1.00 or more) when the syringe portion of the injector is discarded with each use. Additionally, there is the challenge in developing countries where lack of understanding of viral theory and/or a general hoarding mentality discourages following generally accepted protocols within all aspects of health and hygiene. With the identification of blood-borne pathogens like HIV, Hepatitis B, Hepatitis C and others, the need to follow proper protocols becomes more critical. 
     In the past, jet injectors such as Ped-O-Jet®, Ammo-Jet®, and similar mass campaign jet injectors were brought to health care systems. Such injectors had no provision for preventing the transfer of blood-borne pathogens except through the complicated disassembly and disinfecting process. In mass immunization campaigns these types of injector systems fell out of favor starting in the mid and late 1980&#39;s when it was determined that bodily fluids are easily transmitted from one patient to another. 
     To eliminate the possible transmission of blood-borne pathogens between individuals, disposable or partially disposable jet injector systems were developed. Bio-Jet®, J-Tip®, and others characterize this type of jet injector. General acceptance of these units is limited by relatively high direct costs, even in developed countries like the United States. The standard paradigm of breaking the contamination transmission chain has been addressed by either syringe disposal or designing the syringe so it can easily be decontaminated. Currently, there exists a steadily growing danger of the epidemic diseases (AIDS, hepatitis, tuberculosis and other viral diseases transferred through blood) being transmitted between individuals through the use of needleless injectors. 
     The traditional needleless injectors comprise the basic design, a housing with an inner power unit, a medication unit, and a nozzle. The function of the power unit pumps the medication into an under-plunger cavity of the medication unit chamber and to expel the medication through the nozzle. 
     At the initial stage of needleless injector development, when no check valves were used as a control for the functioning of the medication chamber, a method to prevent foreign particles from entering the injector nozzle was to use a sealed nozzle cap. Such cap was limited by the filling of the medication chamber with medication and could not guarantee contamination prevention. 
     Another approach to the contamination prevention problem has been the use of a disposable, low cost, one-shot nozzle assembly for jet injectors. The nozzle assembly comprises a two-piece molded device incorporating a generally cylindrical nozzle body having a central longitudinal bore of a predefined diameter, extending from a proximal end of the nozzle towards its distal end, terminating in a conical portion of the nozzle. A very small diameter jet-forming bore is formed at the apex of the conical portion of the bore in general. The disadvantage of this device is its lower efficiency (i.e., low vaccination rate) because of poor flow due to the conical design. Moreover, a plastic nozzle element also increases the vaccination cost. 
     A typical jet injector design has additional drawbacks. Even in the practice of using a protective cap, there is a possibility of infection transfer from one person to another by means of fluids (blood, lymph, medication) reflected from the skin surface during injection (“back splash”) that may get on the nozzle and be transferred from one patient to the next. The protective cap can be a one-shot cap, including the injection nozzle. A purpose of this device is to prevent the multiple use of a cap with a nozzle. This is achieved through the removal, replacement, and/or destruction of the cap at the later stage of the injection. However, cross-contamination continues to be problematic because in the injection stage, the contaminated matter can be transferred through the nozzle to inside the injector such as, for example, into the cavity and be transmitted to a new patient through a new cap and nozzle. 
     With all the known devices, there is no guarantee that the minimum safety requirements for cross-contamination prevention, as recently introduced (Glenn Austin et al.,  Gross Contamination Testing of Vaccine Jet Injectors, A Preliminary Report , PATH, Seattle, Wash., 98109), will be achieved. Other studies indicate a very dangerous situation. For example, Russian and Brazilian studies have shown unfavorable data in up to 1.0% of the subjects studied—a level of risk far too great to ignore. 
     When jet injectors were introduced in the 1940&#39;s, they were popular for needle phobic patients or small veined patients. Improvements permitted jet injectors to administer hundreds of millions of vaccinations that saved countless lives. However, when the discovery of pathogen transfer occurred, jet injectors fell out of favor to such an extent that the WHO and the U.S. Department of Defense no longer recommended jet injector. 
     For example, in the mid-1980&#39;s an outbreak of Hepatitis B was caused by use of one high workload injector in a weight loss clinic. See, Canter et al., An Outbreak of Hepatitis B Associated With Jet Injections In A Weight Loss Clinic, Arch. Intern. Med., 150:1923-1927 (1990). 
     Present parenteral injection technology has recently been deemed by the World Health Organization (WHO) to be incompatible with their requirements for the planned Global Programme of Vaccination and Immunization (GPV) initiatives. It is estimated that 6 additional parenteral vaccines will be recommended for childhood vaccination by the year 2005, requiring a total of 3.6 billion immunization injections per year. The total number of parenteral injections, including injected drugs as well as vaccines, will be roughly ten times this number. This is in addition to the hundreds of millions needed in military induction centers, epidemic situations, worldwide immunizations, and veterinary uses. Major health care providers such as UNICEF, the WHO and CDC have recently confirmed that a radical new technology is required that can be used by personnel with minimal training and that is safer, more convenient, and more comfortable than the syringe and needle. (Jodar L., Aguado T., Lloyd J. and Lambert P-H, (1998) Revolutionizing Immunizations Gen. Eng. News 18, p. 6.) 
     In other words, what used to be a continent wide life saver, became an undesirable product. The present invention solves problems associated with pathogen transfer and solves many problems associated with the high costs of disposable units. 
     Coupled with this was that accidental discharge of the medication sometimes occurred. Premature injection could result in an incomplete injection or an injection in the improper situs. 
     Accordingly, there is a need in the art of needleless injection devices to solve the problem of cross-contamination during mass vaccinations. More particularly, there is a need for a protector designed for the nozzle head of needleless injectors, which halts “back splash” contamination, and which is low enough in cost to ensure its practical application as a disposable unit even for mass vaccinations. There is also a need to ensure that the incidence of premature discharge is reduced or eliminated. 
     SUMMARY OF THE INVENTION 
     The foregoing problems are solved and a technical advance is achieved by the present invention. Disclosed is medical injection assembly in which the assembly is adapted to reduce the risk of accidental injection of a patient. Manners of doing so include permitting the injection assembly to fire but blocking the medication stream or stopping the injection assembly from firing in the first place. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is one simple embodiment of the invention showing the injector and cap. 
         FIG. 2  is another embodiment of the invention showing one cap embodiment. 
         FIG. 3  is another embodiment of the invention showing one blocking mechanism. 
         FIG. 4  is another embodiment of the invention showing one blocking mechanism. 
         FIG. 5  is another embodiment of the invention showing one blocking mechanism. 
         FIG. 6  is another aspect of the invention of  FIG. 5 . 
         FIG. 7  is another embodiment of the invention showing one blocking mechanism. 
         FIG. 8  is another embodiment showing the proximal end of the device. 
         FIG. 9  is another embodiment showing an orifice shield. 
         FIG. 10  is the embodiment of  FIG. 9  in operation. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows an embodiment of the invention. Disclosed is a medical device injection assembly  10 . The injection assembly  10  further includes an injector assembly proximal end  12 , an injector assembly distal end  14 , and a distal end orifice  16 . For the purposes of discussion, the terms distal and proximal are used to denote non-exclusive locations. The term “proximal” is used generally to describe the area normally closest to the physician or user. The term “distal” is used generally to describe the area close to the patient or close to the end where the medication exits the device. The medication is dispensed via an injection piston  18  located generally within the injector lumen  20 . Medication is pushed out by the injector piston  18  and the injector head  22 . As the medication flows, it passes through the cap  24 , by passing through the cap proximal face  28  and through the cap distal face  26 . The cap distal face  26  is the face that generally faces the patient&#39;s skin  30 . 
       FIG. 2  demonstrates the cap. Although one configuration of the cap is shown, it should be understood that the cap may be configured in the many ways shown in U.S. patent application Ser. No. 09/685,499, the disclosure of which is expressly incorporated by reference herein. The cap  24  includes a cap distal face  26  and a cap proximal face  28 . The cap  24  also includes a protective layer such as a film  32 . The film  32  may comprise comprises at least one of a plastic, rubber, polymer, polyethylene, polytetrafloroethylene, polyurethane, polyolefin, polypropylene, and polysulfone material; or combination thereof. While the film  32  is shown sandwiched between a first component  34  and a second component  36 , it is understood that the film  32  may be in other locations. The film  32  generally covers the cap orifice  38 . Therefore, the various placements, configurations, or numbers of films present that permit the covering of the cap orifice  38  is contemplated. The cap orifice  38  is configured so that it is coincident with the injector lumen  20  so that medication flowing out will generally travel through the film  32  and through the cap orifice  38  with minimal resistance. 
       FIG. 3  demonstrates one embodiment of the invention. Shown is an injection prevention component  40  generally, but not exclusively, located distal to the distal end orifice  16 . In other embodiments, the injection prevention component may be proximal to part of the cap distal face  26 . In one embodiment, the injection prevention component  40  may comprise an orifice shield  42 , which generally covers or blocks (either partially or completely) the distal end orifice  16 . One non-exclusive purpose of the orifice shield  42  is to interrupt the medication stream flow from the injector. It may do so by either blocking the entire stream path or part thereof. To facilitate the blocking or covering, the orifice shield  42  may be adapted to have a relatively flat face  44  or flat surface to maximize interruption or deflection. The injection prevention component may be attached to the injector assembly  10  via an injection prevention component attachment  46 , which may include screws, adhesive, pins, slides, male-female receptacles, welds, bonds, bolts, or other well known mechanisms for attaching pieces together. The attachment and component may be anywhere along the injector. 
     The device  10  may also be fabricated as an integral piece or as separate pieces with the attachment  46 . Thus, in the embodiment shown, since the cap  24  is not in place, the prevention component  40  extends out and blocks the path of the injector lumen  20 . Thus, medication that sprays or is shot out, will generally impact the component  40  and prevent the accidental injection into the patient. Even if there is only partial blockage of the stream, then injection will likely not occur because the remaining stream may not have the required penetration velocity. Accordingly, the component  40  may be configured or adapted in such as way to be disposed distal to the distal end orifice  16 , proximal to the cap proximal face  28 , or proximal to part of the cap distal face  26 . 
       FIG. 4  is another embodiment of the invention. Shown is the prevention component  40  moved out of the way by the cap  24 . As the cap  24  moves into position, the cap pushes against the prevention component  40  so that it is no longer blocking the distal end orifice  16 . Since the cap  24  is removable, the assembly  10  may also include a means  48  for biasing the cap. The mechanisms for biasing also are described in U.S. patent application Ser. No. 09/685,633, the disclosure of which is expressly incorporated by reference herein. The assembly  10  may also be configured to provide for an injection prevention component recess  50 , in which the prevention component  40  may reside when the cap is put on. In this regard, the prevention component  40  may be neatly tucked in the recess  50 . The prevention component  40  may also be adapted in such a way that it is totally out of the way of the distal end orifice  16  only when the cap  24  is firmly in place. Thus, as the cap proximal face  28  begins contacting the prevention component  40 , the component  40  will begin to move out of the way of the distal end orifice  16 . Thus, the component  40  can still block until the cap is completely on and in place. Once the cap is ejected off, the component  40  moves back into blocking position. Thus, the component may also include a leaf spring or other resilient/elastic material that can “spring” back into place when unrestrained. 
       FIGS. 5 and 6  demonstrate yet another embodiment of the invention. Shown is the injection prevention component  40  shown as a prevention piston  52 , which is partially disposed within the recess  50 . The prevention piston  52  includes a piston head  54  detachably attached to a lock pin  56 . The lock pin  56  is adapted to move within an injector piston recess  58 . When the lock pin  56  is in the recess  58 , the injector piston  18  cannot move. Also included is a biasing means such as a prevention piston return means  60 , which may include a spring, deformable material (such as rubber or plastic), screw, or the like. One purpose of the return means  60  is to move the prevention piston  52  back out and thus drop the lock pin  56 , and accordingly, any means to bias the prevention piston  52  is contemplated, included those means for biasing the cap described in U.S. patent application Ser. No. 09/685,633. 
     It should be noted that any means for biasing can also include those means known in the art and can further include, but is not limited to, pistons, gears, rods, springs, worm gears, screws, deformable materials, electromagnets, optical components, and jacks. The means for biasing may also include various driving mechanisms, such as pneumatics, hydraulics, or manual drives. In addition, the means for biasing may also include phase change materials or other shape memory materials, such as those materials that change size or shape due to temperature application. One such material is Nitinol, which allows for size or shape transformation in its austenite and martensite states. Accordingly, the means for biasing is meant to include not only the structures described herein, but also, any acts or materials described herein, and also include any equivalent structures, equivalent acts, or equivalent materials; or structural equivalents, act equivalents, or material equivalents, to those described herein. 
     As shown in  FIGS. 5 and 6 , when the cap  24  approaches the distal end, it engages the prevention piston  52  and begins moving it inwards, thus compressing or deforming the return means  60 . The lock pin  60 , which was supported by the piston head  54 , no longer has support and falls onto the piston  52  and thereby out of the injector piston recess  58 . 
     Although not shown, the device  10  may be adapted to include a lock pin  56  that protrudes into the injector lumen  20  such that the lock pin  56  may engage the injector head  22 , or be disposed distal to the injector head  22 . Thus, the lock pin  56  need not solely enter the piston recess  58 , but may interact with the piston  18  (or piston drive or release) in any fashion to keep it from moving forward, or otherwise interfere with the forward motion. Another embodiment of the invention may also include the orifice shield  42  as described above to be used in conjunction with the prevention piston assembly shown anywhere herein. 
       FIG. 7  shows yet another embodiment of the invention. Shown is the injector assembly proximal end  12 . In this embodiment, shown is the injector piston  18  and the injector piston biasing means  70 . As described throughout, the means for biasing can also include those means known in the art and can further include, but is not limited to, pistons, gears, rods, springs, worm gears, screws, deformable materials, electromagnets, optical components, and jacks. The means for biasing may also include various driving mechanisms, such as pneumatics, hydraulics, or manual drives. In addition, the means for biasing may also include phase change materials or other shape memory materials, such as those materials that change size or shape due to temperature application. One such material is Nitinol, which allows for size or shape transformation in its austenite and martensite states. Accordingly, the means for biasing is meant to include not only the structures described herein, but also, any acts or materials described herein, and also include any equivalent structures, equivalent acts, or equivalent materials; or structural equivalents, act equivalents, or material equivalents, to those described herein. 
     In operation, as the prevention piston  52  is pushed in the direction from distal to proximal (the direction arrow X), then the piston  52  impacts against an injection prevention component  40 , such as a latch  72 . Latch  72  is adapted to interfere with the means for biasing the injection piston  74 , which as described herein may include any biasing means above. In this regard, as the latch  72  engages or interferes with the means  74 , it prevents the means from biasing the injection piston  18 . As the cap  24  is placed on, it pushes the prevention piston  52  along, which impacts against the latch  72  and pushes the latch  72  into a latch recess  76 . Associated with the latch recess  76  and the latch  72  is a means  78  for biasing the latch  72  back up into the interference position. The means  78  may also include a small wad of rubber or a spring that pushes the latch  72  back into the injector lumen  20 . 
     In addition, the injection prevention component  40  may also be adapted to work in conjunction with orifice shields and/or prevention pistons as described herein. Moreover, the prevention component  40  may be adapted to work in conjunction with pneumatically driven locking means, as described in the contemporaneously filed U.S. patent application, (serial number unknown to be inserted later), entitled Injector Assembly with Driving Means and Locking Means, naming the following inventors, Boris V. Smolyarov and Victor T. Rogatchev, filed on (herewith); the disclosure of which is expressly incorporated by reference herein. In that disclosure, a mechanism including rollers, retainers, annular grooves, and ball locks are disclosed. 
       FIGS. 9 and 10 , show another embodiment of the invention in which the orifice shield  42  interacts with a contained compression means  81 , such as compression spring  81 . The shield  42  pivots along an axle  80 . In  FIG. 9 , when there is no cap pushing against the shield  42 , the spring  81  is uncompressed and thereby pushes shield  42  in the way of the orifice. As the cap is put on, the shield  42  moves out of the way and compresses spring  81 . As with any embodiment, the device may be adapted to hide the shield  42  away into a recess or otherwise out of the way. 
     In yet another embodiment of the invention, the invention may also comprise the various steps of operation. For example, also disclosed is a method of preventing the accidental injection of medication into a patient and reducing the risks of cross contamination during injections, comprising the steps of: 
     (a) loading a cap onto a distal end of an injector; 
     (b) disengaging a locking mechanism to permit a stream of medication to exit the injector; 
     (c) removing the cap after injection; and 
     (d) engaging the locking mechanism to prevent a discharge of the medication. 
     Other steps parallel the steps described herein and the person of ordinary skill in the art would understand how to adapt the mechanism to further perform other steps. Thus, one embodiment of the invention may also include the process of adapting the device to include safety mechanisms as described herein. 
     It should be understood that the foregoing relates only to a limited number of embodiments that have been provided for illustration purposes only. It is intended that the scope of invention is defined by the appended claims and that modifications to the embodiments above may be made that do not depart from the scope of the claims.