Patent Publication Number: US-2002004652-A1

Title: Protective device for a fillable injection syringe

Description:
[0001] This application is a continuation-in-part of application Ser. No. 09/336,405 filed Jun. 18, 1999, which is currently pending. The contents of application Ser. No. 09/336,405 are incorporated herein by reference. 
    
    
     
       FIELD OF THE INVENTION  
       [0002] The present invention pertains generally to syringes for medical use. More particularly, the present invention pertains to protective devices for injection syringes that are filled by the user prior to the administration of an injection. The present invention is particularly, but not exclusively, useful for passively covering and protecting the needle of an injection syringe after its use.  
       BACKGROUND OF THE INVENTION  
       [0003] Recent research from the Centers for Disease Control and Prevention (CDC) shows that approximately 384,000 needle sticks or similar injuries occur among health care workers in U.S. hospitals each year. Unfortunately, each accidental needle stick has the potential to expose a health care worker to a life-threatening virus such as hepatitis or HIV. In addition to the needle sticks that occur in hospitals, accidental needle sticks can also occur in other health care settings. For example, needle stick injuries can occur at clinics or during home health-care. In fact, some studies have estimated that over 600,000 needle sticks occur in the U.S. each year, and approximately 1,000 of these accidental needle sticks result in a life-threatening infection.  
       [0004] For each accidental needle stick, health care providers are obligated to test and counsel the exposed worker. Further, follow-up testing for HIV must be conducted approximately six months after the exposure. It is to be appreciated that the costs associated with the testing, lab work, the workers lost time, and the associated tracking and administrative costs, can be considerable.  
       [0005] Accidental needle sticks can occur in several ways. For example, sudden movement by the patient can cause a health care worker to lose control of a syringe, resulting in injury. Attempts to manually recap a needle following an injection can also result in injury. Moreover, injuries often result when contaminated unprotected needles are left unattended or disposed of improperly. In addition to accidental needle sticks, unnecessary exposure to bloodborne pathogens can result when a health care worker mistakenly reuses a contaminated needle on a patient.  
       [0006] In light of the above, it is an object of the present invention to provide a protective device that passively covers and protects the needle of a medical syringe after first filling the syringe with medicament and then injecting the medicament into a patient. It is another object of the present invention to provide a protective device for the needle of a medical syringe that regulates the amount of needle that is exposed during a sequence of steps that include filling the syringe with fluid medicament from a medicament vial and then injecting a patient with the medicament. It is yet another object of the present invention to provide a protective device that prevents re-use of a contaminated syringe by providing a clear, visible indication that the syringe has been used. Yet another object of the present invention is to provide a protective device for a medical syringe that is easy to use, relatively simple to implement, and comparatively cost effective.  
       SUMMARY OF THE PREFERRED EMBODIMENTS  
       [0007] A device for protecting a hollow needle, after it has been used with a syringe to inject a fluid medicament into a patient, includes a cylindrical-shaped barrel piece that is slidably mounted over the needle to completely cover or selectively expose different lengths of the hollow needle. Specifically, a relatively short portion of the needle is exposed prior to filling the syringe with the medicament, and subsequently prior to injecting the medicament into the patient. After an injection, however, the barrel piece completely covers the hollow needle.  
       [0008] In accordance with the present invention, the device includes an adapter that is attached to the proximal end of the needle. With this attachment, the needle extends distally from the adapter to define an axis. The barrel piece, which is formed with an aperture, is then slidably mounted on the adapter with the needle projecting through the aperture to allow for axial movement of the barrel piece over the needle. Additionally, a biasing mechanism, such as a spring, is mounted between the adapter and the barrel piece to urge the barrel piece in a distal direction, relative to the adapter.  
       [0009] An important aspect of the present invention involves the cooperative interaction between the adapter and the barrel piece. To effect this interaction, a plug extends from the adapter and into a slot that is formed on the barrel piece. In detail, this slot is formed with a start position (first position), and two axially aligned, parallel tracks which sequentially establish four additional positions (second, third, fourth and fifth positions). Further, one of these tracks (a first track) is positioned between the start position and the other track (a second track). Within this configuration, relative to the axis, the start position is azimuthally offset from the first track, and is on the opposite side of the first track from the second track. Further, a first guide ramp is formed in the slot to direct the plug in its movement from the start position into the first track. Also, a second guide ramp is formed in the slot to direct the plug in its movement from the first track into the second track.  
       [0010] In operation, the plug on the adapter is initially located in the start position with a relatively short portion of the hollow needle extending distally from the barrel piece. In this configuration, the adapter is engaged with the syringe to establish fluid communication between the syringe and the hollow needle. To then fill the syringe with fluid medicament, the needle is inserted through the stopple of a medicine vial. In response, the medicine vial pushes against the barrel piece to move it in a proximal direction back over the adapter. This also moves the plug from the start position. Specifically, the plug is directed by the first guide ramp into the first track. Further proximal movement of the barrel piece continues until the plug is stopped in the second position at the distal end of the first track. When the needle is disengaged from the medicine vial, the biasing mechanism urges the barrel piece forward in a distal direction until the plug is stopped at the proximal end of the first track (third position). In this configuration, a relatively short portion of the needle again extends distally from the barrel piece. The syringe is now ready for injecting the fluid medicament into the patient.  
       [0011] With the syringe filled and the distal end of the hollow needle slightly exposed, the needle can be accurately positioned against the patient for an injection. Then, as the needle is pushed into the body of the patient, a reaction force is generated against the barrel piece. This reaction force causes the barrel piece to again move in a proximal direction back over the adapter. This time, however, the plug is directed by the second guide ramp into the second track. This movement continues until the plug is stopped in a fourth position at the distal end of the second track. The syringe can then be used to inject the fluid medicament into the patient.  
       [0012] Upon the completion of an injection, the needle is withdrawn from the patient and the reaction force of the body against the barrel piece is removed. The biasing mechanism then causes the plug to move out of the fourth position and along the second track and into the fifth position at the proximal end of the second track. For the present invention, this fifth position can be azimuthally offset from the second track, and it can be configured with a detent that will prevent further axial movement of the plug relative to the slot. Stated differently, the detent (fifth position) will effectively lock the barrel piece to the adapter and over the hollow needle. Importantly, in this configuration, the barrel piece completely covers the hollow needle to protect the user from unwanted needle sticks after the injection has been completed. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0013] The novel features of this invention, as well as the invention itself, both as to its structure and its operation, will be best understood from the accompanying drawings, taken in conjunction with the accompanying description, in which similar reference characters refer to similar parts, and in which:  
     [0014]FIG. 1 is a prospective view of a syringe having a protective device in accordance with the present invention;  
     [0015]FIG. 2 is a sectional view of a portion of the syringe as seen along line  2 - 2  in FIG. 1;  
     [0016]FIG. 3 is a plan view of an adapter in accordance with the present invention;  
     [0017]FIG. 4A is a plan view of a portion of a syringe, shown with the protective device in its initial position wherein the needle tip is slightly extended for locating the opening of a medicament vial;  
     [0018]FIG. 4B is a plan view of a portion of a syringe, shown with the protective device in its second position wherein the needle tip is extended for insertion into a medicament vial to allow the syringe to be filled with medicament;  
     [0019]FIG. 4C is a plan view of a portion of a syringe, shown with the protective device in its third position wherein the needle tip is slightly extended for locating an injection point on a patient;  
     [0020]FIG. 4D is a plan view of a portion of a syringe, shown with the protective device in its fourth position wherein the needle tip is extended to the proper penetration depth for an injection; and  
     [0021]FIG. 4E is a plan view of a portion of a syringe, shown with the protective device in its final position wherein the needle tip is covered and protected by the barrel piece. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
     [0022] Referring to FIG. 1, a syringe in accordance with the present invention is shown and generally designated  10 . As shown in FIG. 1, the syringe  10  includes a protective device  12  for covering the hollow needle  14  of the syringe  10  after use. An optional cap  16  can be included as part of the syringe  10  to cover the exposed part of the needle  14  before use. Referring now to FIG. 2, it can be seen that the protective device  12  includes a barrel piece  18  and an adapter  20 . With cross reference to FIGS. 2 and 3, it can be appreciated that, the adapter  20  is preferably shaped as a hollow cylinder having an inner wall  22  and an outer wall  24 .  
     [0023] In accordance with the present invention, the adapter  20  is formed with a coupling  26 , such as a luer type coupling, mounted on the inner wall  22  of the adapter  20 . As shown, the coupling  26  attaches the hollow needle  14  to the adapter  20 . It is to be appreciated that preferably a substantially straight, hollow needle  14  (thereby defining axis  28 ) is used in conjunction with the present invention. The distal end  30  of the hollow needle  14  is formed as a sharp tip suitable for piercing the skin of the patient, while the proximal end  32  is attached to the adapter  20  via the coupling  26 . For the present invention, the cylindrical adapter  20  is centered on the needle axis  28  when the needle  14  is attached to the adapter  20 , as shown in FIG. 2.  
     [0024] Referring now to FIGS. 1 and 2, it can be seen that the coupling  26  also attaches the adapter  20  to the body  34  of the syringe  10 . As shown, the body  34  is formed with a medicament chamber  36 . Further shown, the coupling  26  attaches the body  34  of the syringe  10  to the adapter  20  with the medicament chamber  36  in fluid communication with the hollow needle  14 . The syringe  10  also includes a plunger  38 , engageable with the medicament chamber  36 . With this cooperation of structure, the plunger  38  can be advanced into the medicament chamber  36  to expel fluid from the chamber  36 , through the hollow needle  14 , and then out of the distal end  30  of the needle  14 .  
     [0025] Referring still with cross reference to FIGS. 1 and 2, it can be seen that the barrel piece  18  is formed with a cylindrically shaped wall having an inner radius large enough to allow the adapter  20  to be disposed within the barrel piece  18 . As shown, an optional nose  42  is formed in the barrel piece  18 , extending from the cylindrical wall  40  at one end. The other end of the cylindrical barrel piece  18  is preferably open. As shown, the nose  42  of the barrel piece  18  is preferably closed except for a small aperture  44  for receiving the hollow needle  14 .  
     [0026] Referring now with cross reference to FIGS. 1, 2 and  3 , it can be seen that the adapter  20  is formed with a plug  46  that extends radially from the outer wall  24  of the adapter  20 . Further shown, a multi-branch slot  48  extends through the cylindrical wall  40  of the barrel piece  18  for engagement with the plug  46  of the adapter  20 . With this combination of structure, the barrel piece  18  can be positioned over the adapter  20  with the plug  46  formed in the adapter  20  extending into the slot  48  formed in the barrel piece  18 , as shown in FIG. 2. Further, as shown, the barrel piece  18  is substantially centered on the axis  28  of the needle  14  when positioned on the adapter  20 . FIG. 2 further shows that a spring  50  is compressed inside the barrel piece  18  with one end of the spring  50  in contact with the adapter  20  and one end of the spring  50  in contact with the barrel piece  18 . With the spring  50  positioned in this manner, the barrel piece  18  and adapter  20  are urged in opposite directions along the needle axis  28 . It is to be appreciated that the barrel piece  18  and adapter  20  are capable of both axial and rotational movement relative to each other, restricted only by the limited ability of the plug  46  to move within the slot  48 .  
     [0027] Referring to FIG. 2, it is to be appreciated that movement between the adapter  20  and barrel piece  18  is driven by two opposing forces, an internal force caused by a spring  50  and an external force arising when the nose  42  of the barrel piece  18  is pressed against a surface such as the medicament vial  52  (shown in FIG. 4B) or the patient  54  (shown in FIG. 4D). The branched shape of the slot  48  is designed to regulate the distance the distal end  30  of the needle  14  extends from the nose  42  of the barrel piece  18 .  
     [0028]FIGS. 4A through 4E show a sequence of steps that include filling the syringe  10  with fluid medicament from a medicament vial  52  and then injecting a patient  54  with the medicament. During this sequence, as shown, the nose  42  of the barrel piece  18  is pressed against the medicament vial  52 , then released, pressed against the skin of the patient  54  and then released. Also during this sequence, the barrel piece  18  is forced to move axially, back and forth, relative to remaining portions of the syringe  10 . It is to be appreciated, however, that these movements will be limited by the slot  48  and plug  46  assembly. Specifically, five stop points  56 ,  58 ,  60 ,  62  and  64  formed in the slot  48  are provided to stop and hold the plug  46  and thereby regulate axial movement of the barrel piece  18  initially and during the sequence of steps.  
     [0029] Referring now to FIG. 4A, the slot  48  is configured with a stop point  56  to initially hold the plug  46  in a position where the distal end  30  of the needle  14  extends only slightly from the nose  42  of the barrel piece  18 . This slight extension allows the user to locate the tip of the needle  14  in the medicament vial  52  (shown in FIG. 4B). Specifically, the stop point  56  prevents the spring  50  from moving the barrel piece  18  in a distal direction relative to the rest of the syringe  10 .  
     [0030] Referring now to FIG. 4B, it can be seen that the nose  42  of the barrel piece  18  is to be pressed against the medicament vial  52  during insertion of the distal end  30  of the needle  14  into the medicament vial  52 . As the barrel piece  18  moves in the proximal direction in response to the pressing force caused by the medicament vial  52 , the plug  46  relocates in the slot  48  toward stop point  58 . When the plug  46  reaches the stop point  58 , further proximal movement by the barrel piece  18  due to the pressing force is prevented. Preferably, as shown, the slot  48  is designed with the stop point  58  located at a point to extend the distal end  30  of the needle  14  at a distance that will allow the syringe  10  to be easily filled with medicament from the medicament vial  52 .  
     [0031] Referring now to FIG. 4C, the syringe  10  is shown after filling (i.e. the needle  14  is removed from the medicament vial  52  (shown in FIG. 4A), releasing the force on the barrel piece  18  due to the medicament vial  52 . Without the external force, the spring  50  (shown in FIG. 2) translates the barrel piece  18  distally to re-cover the portion of the needle  14  that was exposed during filling. During the translation, the plug  46  relocates within the slot  48  towards stop point  60 . When the plug  46  reaches stop point  60 , further distal movement by the barrel piece  18  by the spring  50  is prevented. As shown, stop point  60  is preferably located in the slot  48  at a point where the distal end  30  of the needle  14  is again only slightly extended from the nose  42  of the barrel piece  18 . This slight extension allows the user to locate the distal end  30  of the needle  14  at a suitable injection point.  
     [0032] Comparing FIGS. 4A and 4C, it can be seen that stop point  56  and stop point  60  result in approximately the exposure of needle  14 , yet stop point  56  and stop point  60  are located at different positions along the slot  48 . Specifically, as shown, stop points  56 ,  58  and  60  are azimuthally offset relative to the needle axis  28 . The slot  48  is designed in this manner to allow the plug  46  to sequentially relocate from stop point  56  to stop point  58  and then to stop point  60 , in order, during the fill sequence. To achieve this sequential movement of the plug  46 , the guide ramp  66  of the slot  48  between stop points  56  and  58  is sloped relative to the needle axis  28 . Further, as shown, a guide ramp  68  is formed in the slot  48  between stop points  58  and  60  to catch the plug  46  and guide the plug  46  into stop point  60 . Thus, it is to be appreciated that as the plug  46  relocates along the slot  48  through from stop points  56  to stop point  58 , the barrel piece  18  and adapter  20  rotate relative to each other due to the slope of the guide ramps  66 ,  68 .  
     [0033]FIG. 4D shows the syringe  10  after the syringe  10  has been filled and the distal end  30  of the needle  14  has been inserted into the patient  54  for an injection. During insertion, it is to be appreciated that pressure is exerted on the nose  42  of the barrel piece  18  by the skin of the patient  54 . This pressure moves the barrel piece  18  in the proximal direction causing the plug  46  to relocate in the slot  48  toward stop point  62 . As shown, stop points  60  and  62  are azimuthally offset relative to the needle axis  28 . Guide ramp  70  is formed in the slot  48  between stop points  60  and  62  to catch the plug  46  and guide the plug  46  into stop point  62 . Thus guide ramp  70  ensures that the plug  46  sequentially relocates from stop point  60  to stop point  62  during penetration of the skin  54  by the needle  14 . Once the plug  46  reaches the stop point  62 , further proximal movement by the barrel piece  18  due to the skin pressure is prevented. Through proper positioning of stop point  62  on the barrel piece  18 , the depth of needle  14  penetration into the patient  54  can be controlled.  
     [0034] Referring now to FIG. 4E, the syringe  10  is shown after the injection, with the syringe  10  removed from the patient. As shown, the pressure on the barrel piece  18  due to contact with the skin of the patient  54  (shown in FIG. 4D) has been released. Without the external force, the spring  50  (shown in FIG. 2) translates the barrel piece  18  distally to fully cover the exposed portion of the needle  14 . During the translation, the plug  46  relocates within the slot  48  towards stop point  64 . When the plug  46  reaches the stop point  64 , further movement by the barrel piece  18  is prevented. For the present invention, the slot  48  is formed with a detent at stop point  64  to hold and lock the plug  46 . Thus, after an injection, the barrel piece  18  becomes locked in a position where the needle  14  is fully covered and protected.  
     [0035] While the particular devices and methods as herein shown and disclosed in detail are fully capable of obtaining the objects and providing the advantages herein before stated, it is to be understood that they are merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended to the details of construction or design herein shown other than as described in the appended claims.