Abstract:
A disposable needle assembly having a holster for receiving and piercing a vial of anesthetic in which means are provided to facilitate the removal of the spent vial from the holster.

Description:
FIELD OF THE INVENTION  
         [0001]    The invention is a flexible conduit and carrier assembly for conveying liquid such as local anesthetic under elevated pressure from a vial to a hollow needle adapted to be implanted in the tissue, particularly the gingival tissue of the mouth.  
         BACKGROUND OF THE INVENTION  
         [0002]    The applicant&#39;s U.S. Pat. Nos. 4,747,824 and 5,180,371 disclose apparatus and method by means of which local anesthetic can be administered virtually without pain into the tissues, particular the mouth. In accordance with this invention, a vial of anesthetic is mounted in a holster unit detachably mounted at a programmed and controllable pumping station which forces the anesthetic from the vial at predetermined flow rates with greater precision than can be achieved with conventional hand syringes. The holster includes means to pierce the rubber diaphragm of the vial and to convey the liquid through a flexible microbore tube to a handle assembly carrying a conventional hollow needle to inject the anesthetic into the tissue.  
           [0003]    Such holster, flexible conduit and needle assemblies must be disposable for sanitary reasons and must, therefore be relatively inexpensive. On the other hand, they must be engineered so they can quickly and easily be mated with anesthetic vials and then attached to the pumping station and just as easily be disassembled and not infrequently re-loaded for use on the same patient. They must also be light in weight, able to withstand high liquid pressures and readily manipulated at difficult injection sites.  
           [0004]    The object of the invention, therefore, is to provide an assembly which meets all of these difficult and somewhat incompatible design criteria.  
         BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION  
         [0005]    In accordance with the invention, a holster design is provided which, as a single die cast unit, is capable of receiving a sealed vial of anesthetic and of automatically puncturing the membrane seal at the head end of the vial by means of an integral, sharppointed, hollow probe at the base of the holster to tap into the reservoir of liquid anesthetic. The holster includes tab means at its forward end to detachably lock it to the pumping station and to actuate a ram to drive the plug or piston in the rearward end of the vial into the vial&#39;s reservoir to force the liquid through the flexible microbore conduit to the needle under a wide range of pressures. The flexible conduit is coupled to both the holster and the needle handle in a high pressure seal.  
           [0006]    Because it is frequently required that a second vial of anesthetic be used for the same patient, it should be possible to quickly detach the disposable assembly from the pump, eject the spent vial and insert a fresh vial. In accordance with the invention, swift removal of the spent vial is facilitated by arranging the geometry of the holster so that the vial can be gripped to detach it from the holster, when it is to be discarded. This can be achieved, for example, by means of a pair of complementary diametrically opposed finger apertures in the side wall of the holster to enable the vial to be tightly gripped and pulled out of the holster against the friction of the probe gripped by the rubber membrane of the vial.  
       
    
    
     DESCRIPTION OF THE DRAWINGS  
       [0007]    [0007]FIG. 1 is a plan view of a holster, flexible conduit and needle assembly embodying the present invention, and also showing, disassembled, an anesthetic vial and a portion of a pumping station;  
         [0008]    [0008]FIG. 2 is a view in longitudinal vertical section of the needle end of the handle portion;  
         [0009]    [0009]FIG. 3A is a view in vertical longitudinal section of the holster portion of FIG. 1;  
         [0010]    [0010]FIG. 3B is a view in horizontal longitudinal section of the holster portion of FIG. 1; and  
         [0011]    [0011]FIGS. 4A and 4B are two views in cross section showing the front end of the holster inserted in the pumping station, the latter showing the holster rotated 90° to engage the locking tabs and to start the microprocessor.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0012]    Referring to FIG. 1, the invention is shown as embodied in a disposable assembly  10  having an open-ended tubular holster  11  for receiving a vial or cartridge  11   a,  of anesthetic and for attachment to a programmed pumping station  12 . The assembly  10  includes a flexible, microbore tube or conduit  13  coupled to a handle assembly  14  having a rigid elongated carrier  15 , the free end of which is joined to a hollow needle  16  connected to the conduit  13  in fluid-tight relationship, as best seen in FIG. 2.  
         [0013]    The flexible conduit  13  is threaded through a central bore  17  in the carrier  15  to receive the base end of the hollow needle  16 . The needle is carried by a cap  18  having a needle sealing hub  19  and fitted over the free end of the carrier  15 , also in sealing relationship. The pencil-like geometry of the handle assembly enables it to be held between the forefinger and the thumb of the doctor to enable the careful implantation of the needle in the most difficult injection sites.  
         [0014]    The holster  11  as best seen in FIGS. 1, 3A and  3 B is preferably cast in plastic as a unitary structure having a hollow cylindrical body to receive at its free or open end the charged anesthetic vial  11   a,  head or front end  11   b  first. The head end of a conventional anesthetic vial includes a penetrable rubber seal  11   c  held by a metal sealing ring while the back end is sealed by a plug or piston  11   d  which is slidable into the anesthetic reservoir  11   e  of the vial to drive the liquid forward.  
         [0015]    The open or forward end of the holster  11  includes a pair of radially extending locking tabs  20  and  21  (best seen in FIG. 3B and 4B) while the base or closed end is formed with a central, external hub  22  adapted to receive the flexible conduit  13  in sealing relationship. The base end is also formed internally with a hollow, molded, piercing probe  22 A having a tip sharpened in at least three planes to define a piercing tip capable of penetration of the rubber seal  11  c of the vial when it is inserted into the holster. Thus the flexible, microbore conduit  13  is connected to the anesthetic reservoir  11   e.    
         [0016]    With the vial  11   a  fully seated in the holster  11  with the probe  22 a penetrating the rubber seal  11   c,  the assembly  10  is ready to be releasably locked to the pre-programmed pumping station  12 . To this end, the wall of the pumping station is formed with a circular aperture  12 a with diametrically opposed radial extensions  12 b and  12 c (best seen in FIG. 4B) to receive the radial tabs  20  and  21  of the holster. The holster is then rotated 90° counter-clockwise as viewed in FIGS. 4A and 4B to dispose the locking tabs behind the wall  12 . At the same time the locking tab  20  rotates into engagement with a programming switch  22  connected to a microprocessor  23  in the pumping station  12  to actuate a plunger  24  to drive the plunger into the piston  11   d  in the vial  11   a.  The plunger is then controlled by the doctor and the micro-processor to complete the injection in accordance with the teaching of the applicant&#39;s aforesaid patents.  
         [0017]    When the injection is completed (or the vial exhausted), the holster is then detached from the pumping station by reversing the insertion procedure. Removal of the vial from the holster requires that the rubber seal  11   c,  which is in tight frictional engagement with the piercing probe  22 a, be readily detached from the probe. This is accomplished in accordance with the invention by forming in the holster diametrically opposed finger apertures  25 a and  25 b so that the vial within the holster can be tightly gripped with a force enabling the doctor or a technician to pull the vial away from the piercing probe in minimum time. A fresh cartridge or vial of anesthetic can then be inserted in the holster to provide for additional anesthetic to be injected into the same patient without any delay which would adversely affect the process. Alternatively, the geometry of the holster can be such that the length of the vial exceeds the length of the holster so that the end of the vial can be gripped when the holster is detached from the pumping station  12 .  
         [0018]    While the invention has been described above in reference to a preferred embodiment thereof, it will be understood that it can take other forms and arrangements. The invention should not, therefore, be regarded as limited except as set forward with the following claims.