Abstract:
A needle assembly adapted for fluid communication with a vial containing a substance to be delivered to a subject, the needle assembly including a needle held in a needle holder, the needle holder confined to move in a housing, and an activation mechanism for activating delivery of the substance through the needle, the activation mechanism including a safety latch that initially impedes movement of the needle holder, wherein when the safety latch is placed on the subject, the safety latch moves to a position that permits moving the needle holder to cause the needle to protrude outwards of the housing to pierce the subject to allow administration of the substance to the subject.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention generally relates to external drug pumps, and particularly to a needle assembly for a drug pump with safety features. 
       BACKGROUND OF THE INVENTION 
       [0002]    External drug pumps are typically used to deliver to patients substances which contain large molecules which cannot be digested when administered orally, such as insulin. Typically, the pump is adhered to the abdomen of the patient and delivers the substance to the patient via a cannula that is inserted into the patient&#39;s skin. 
       SUMMARY OF THE INVENTION 
       [0003]    The present invention seeks to provide an improved needle assembly for a drug pump with safety features, as is described more in detail hereinbelow. 
         [0004]    There is thus provided in accordance with an embodiment of the present invention a needle assembly adapted for fluid communication with a vial containing a substance to be delivered to a subject, the needle assembly including a needle held in a needle holder, the needle holder confined to move in a housing, and an activation mechanism for activating delivery of the substance through the needle, the activation mechanism including a safety latch that initially impedes movement of the needle holder, wherein when the safety latch is placed on the subject, the safety latch moves to a position that permits moving the needle holder to cause the needle to protrude outwards of the housing to pierce the subject to allow administration of the substance to the subject. 
         [0005]    In accordance with an embodiment of the present invention the safety latch is pivotally mounted on a base about a pivot. The safety latch may be arranged to selectively pivot in and out of a complimentary shaped groove formed in the base. 
         [0006]    In accordance with an embodiment of the present invention the safety latch includes a first arrestor at a distal end thereof and a second arrestor proximal to and spaced from the first arrestor, the first and second arrestors being arranged for selectively arresting motion of the needle holder. 
         [0007]    In accordance with an embodiment of the present invention the safety latch initially impedes movement of the needle holder by being in a position wherein the first arrestor abuts against an ear that projects from a bottom portion of the needle holder, thereby arresting movement of the needle holder. 
         [0008]    In accordance with an embodiment of the present invention when the safety latch is placed on the subject, the safety latch moves to a position such that the first arrestor moves away from the ear of the needle holder to permit movement of the needle holder. 
         [0009]    In accordance with an embodiment of the present invention a control button is provided that has a shaft. A slanted tongue protrudes from a periphery of the shaft at a lower end thereof. When the safety latch is placed on the subject and the control button is moved, the slanted tongue applies a force against a ramp formed on the needle holder, thereby causing the needle holder to move and to rotate as the needle moves outwards of the housing. The needle holder can rotate sufficiently so that the ear is arrested by the second arrestor. Moving the safety latch off the subject causes the second arrestor to move away from the ear and causes the needle holder to continue to rotate due to the slanted tongue still applying a force on the ramp. The needle holder rotates until the slanted tongue moves off the ramp, whereupon the needle holder moves so that the ear gets caught on a shoulder formed on the housing, thereby trapping the needle in the housing. 
         [0010]    In accordance with an embodiment of the present invention when the control button is moved so that the slanted tongue applies the force against the ramp, the control button becomes locked in the housing. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    The present invention will be understood and appreciated more fully from the following detailed description taken in conjunction with the drawings in which: 
           [0012]      FIGS. 1 and 2  are simplified illustrations of apparatus for administering a substance to a subject, in accordance with an embodiment of the present invention; and 
           [0013]      FIGS. 3-9  are simplified illustrations of operation of an activation mechanism of the apparatus of  FIGS. 1-2 , constructed and operative in accordance with an embodiment of the present invention, wherein: 
           [0014]      FIG. 3  is a simplified illustration of a safety latch in the down position, this being the nominal (starting) position as long as the apparatus has not yet been placed upon the user&#39;s body, and a needle holder cannot be pushed down; 
           [0015]      FIG. 4  is a simplified illustration of the safety latch in the up position, which is the position when the apparatus  10  has been placed upon the user&#39;s skin; 
           [0016]      FIG. 5  is a simplified illustration of pressing the control button down which moves the needle holder downward, thereby piercing the patient&#39;s skin with the needle; 
           [0017]      FIG. 6  is a simplified illustration of the needle holder held in place; 
           [0018]      FIG. 7  is a simplified illustration of lifting the apparatus off the patient&#39;s body after finishing the drug administration, which causes the safety latch to move back to the down position; 
           [0019]      FIG. 8  is a simplified illustration of the needle holder moving back up and getting stopped in the up position with the needle retracted back into the housing of the apparatus; and 
           [0020]      FIG. 9  is a simplified illustration of the final position of the needle trapped back inside the apparatus in a safe position. 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0021]    Reference is now made to  FIGS. 1 and 2 , which illustrate apparatus  10  for administering a substance, for example, insulin, to a subject, in accordance with an embodiment of the present invention. Typically, apparatus  10  includes a vial  12  ( FIG. 2 ) that contains the substance to be administered to a subject. The term vial encompasses any kind of reservoir or container for storing the substance to be administered and is not limited to any size or shape. 
         [0022]    As seen in  FIG. 2 , vial  12  may be mounted on a housing base  14 . A housing top  16  ( FIG. 1 ) may cover the assembly and may be secured to base  14 . For some applications, a vial piercing mechanism  18  is movably (e.g., rotatably) coupled to housing base  14  and pierces the distal end of vial  12 . The substance to be administered flows from vial  12  to an activation mechanism  20  via a tube (not shown). The activation mechanism  20  may have a control button  22  and is typically coupled to the housing base  14 . The activation mechanism  20  is configured to insert a cannula and/or a needle through the subject&#39;s skin and to deliver the substance via the cannula and/or the needle. The embodiments of the invention are described with reference to a needle alone, but apply as well to a needle disposed in a cannula or any other delivery device. The term “needle” is used throughout the specification and claims to encompass all such delivery devices. 
         [0023]    Apparatus  10  typically includes a motor, a battery and a control unit (all not shown). After the needle has penetrated the skin of the patient, the control unit controls operation of the motor to administer a controlled amount of the substance to the patient at a controlled rate of delivery. Of course, the needle assembly of the present invention can be used in other applications and does not have to be used with a controlled motorized delivery system. 
         [0024]    Reference is now made to  FIGS. 3-9 , which illustrate operation of activation mechanism  20 , constructed and operative in accordance with an embodiment of the present invention. 
         [0025]    In a non-limiting embodiment of the invention, activation mechanism  20  includes control button  22  having a shaft  24  which is arranged to move (vertically downwards in the sense of the drawings) against a needle holder  26  ( FIG. 4 ) which holds a needle  28 . The shaft  24  and the needle holder  26  are both confined to move in a (e.g., tubular) housing  30 , but there is a difference in their movements. Shaft  24  is confined to translate downwards in housing  30  with no rotation. In contrast, needle holder  26  can not only translate but can also rotate in housing  30 , as will be explained more in detail below. 
         [0026]    The movement of needle holder  26  is selectively impeded by a safety latch  32 , which is pivotally mounted on housing base  14  about a pivot  34 . Safety latch  32  is arranged to selectively pivot in and out of a complimentary shaped groove  36  ( FIG. 2 ) formed in housing base  14 . Safety latch  32  includes a first arrestor  36  at a distal end thereof and a second arrestor  38  proximal to and spaced from the first arrestor  36 . The arrestors may be shaped as lugs or other projections or any other structure suitable for arresting motion of needle holder  26  as will be explained below. 
         [0027]      FIG. 3  shows safety latch  32  in the down position, which is its nominal (starting) position as long as apparatus  10  has not yet been placed upon the user&#39;s body. In this position, first arrestor  36  abuts against an ear  40  that projects from a bottom portion of needle holder  26 . It is noted that pushing ear  40  down against a surface  42  of first arrestor  36  will not cause downward movement of needle holder  26  because this will simply pivot first arrestor  36  about the pivot  34  causing another surface  44  of first arrestor  36  to abut against the bottom surface of housing  30 . Thus, when safety latch  32  in the down position, needle holder cannot be pushed down (in the sense of the drawing of course). 
         [0028]      FIG. 4  shows safety latch  32  in the up position (that is, it has pivoted upwards about pivot  34 ), which is the position when apparatus  10  has been placed upon the user&#39;s skin. First arrestor  36  has been moved out of the way of ear  40  of needle holder  26 . 
         [0029]    In this position, control button  22  may be pressed down to the position shown in  FIG. 5 . Pressing control button  22  down causes two actions. First, shaft  24  becomes locked in the down position in housing  30 , such as by means of one or more splines  46 , which radially project outwards from shaft  24 , sliding past one or more chamfered resilient tongues  48  mounted in housing  30 . After splines  46  sliding past tongues  48 , splines  46  become locked in place by the action of the tongues  48  resiliently snapping back in place over them. 
         [0030]    Second, pressing control button  22  down moves needle holder  26  downward. A slanted tongue  50  protrudes from the periphery of shaft  24  at a lower end thereof. Needle holder  26  may be cylindrical and may enter a hollow portion of shaft  24 . When control button  22  is pressed down, the slanted tongue  50  rides against a slanted ramp  52  formed on needle holder  26 . This action causes needle holder  26  to move down (thereby piercing the patient&#39;s skin) and to rotate counterclockwise as viewed from above control button  22 . 
         [0031]    As seen in  FIG. 6 , needle holder  26  rotates sufficiently so that ear  40  is arrested by second arrestor  38 . The needle  28  remains inserted in the patient for the duration of the drug administration. 
         [0032]    It is noted that in the position of  FIG. 6 , slanted tongue  50  applies a downward force on ramp  52  of needle holder  26 , but this force does not result in any movement of needle holder  26  on account of ear  40  being arrested by second arrestor  38 . 
         [0033]    After finishing the drug administration, apparatus  10  is lifted off the patient&#39;s body. This causes safety latch  32  to move back to the down position as shown in  FIG. 7 , thereby moving second arrestor  38  away from ear  40 . A biasing device  47 , such as a leaf spring biased between first arrestor  36  and housing base  14 , may be employed to impart a returning force on safety latch  32  to move it back to the down position. Alternatively, an adhesive (not shown) may be used to stick the apparatus  10  on the patient&#39;s skin. When apparatus  10  is pulled off the skin, the adhesive resists the force to pull the device off the skin and this resistive force may impart the returning force on safety latch  32  to move it back to the down position. Since slanted tongue  50  applies a downward force on ramp  52 , needle holder  26  is now free to continue rotating counterclockwise by the action of slanted tongue  50  on ramp  52 . Needle holder  26  rotates counterclockwise until slanted tongue  50  slides off ramp  52 . At this point, needle holder  26  jumps back up and ear  40  gets caught on a shoulder  54  formed on housing  30  as shown in  FIG. 8 . In this position, needle holder  26  cannot move back down because of ear  40  being arrested against shoulder  54 .  FIG. 9  shows the final position of the needle  28  trapped back inside apparatus  10  in a safe position. Apparatus  10  may now be safely discarded. 
         [0034]    It will be appreciated by persons skilled in the art that the present invention is not limited by what has been particularly shown and described hereinabove. Rather the scope of the present invention includes both combinations and subcombinations of the features described hereinabove as well as modifications and variations thereof which would occur to a person of skill in the art upon reading the foregoing description and which are not in the prior art.