Abstract:
A low profile wearable infusion device comprises a generally cylindrical reservoir having a diameter greater than its height and a drive that causes a piston to move an incremental distance within the reservoir to cause the device to dispense a dose of medicament.

Description:
PRIORITY CLAIM 
       [0001]    The present application is a Continuation of copending U.S. patent application Ser. No. 11/906,182, filed Sep. 28, 2007, which application is incorporated herein by reference in its entirety. 
     
    
     BACKGROUND 
       [0002]    The present invention relates to infusion devices and more particularly to such devices that enable liquid medicaments to be conveniently and safely self-administered by a patient. 
         [0003]    Tight control over the delivery of insulin in both type I diabetes (usually juvenile onset) and type II diabetes (usually late adult onset), has been shown to improve the quality of life as well as the general health of these patients. Insulin delivery has been dominated by subcutaneous injections of both long acting insulin to cover the basal needs of the patient and by short acting insulin to compensate for meals and snacks Recently, the development of electronic, external insulin infusion pumps has allowed the continuous infusion of fast acting insulin for the maintenance of the basal needs as well as the compensatory doses (boluses) for meals and snacks. These infusion systems have shown to improve control of blood glucose levels. However, they suffer the drawbacks of size, cost, and complexity. For example, these pumps are electronically controlled and must be programmed to supply the desired amounts of basal and bolus insulin. This prevents many patients from accepting this technology over the standard subcutaneous injections. 
         [0004]    Hence, there is a need in the art for a convenient form of insulin treatment which does not require significant programming or technical skills to implement to service both basal and bolus needs. Preferably, such a treatment would be carried out by an infusion device that is simple to use and mechanically driven negating the need for batteries and the like. It would also be preferable if the infusion device could be directly attached to the body and not require any electronics to program the delivery rates. The insulin is preferably delivered through a small, thin-walled tubing (cannula) through the skin into the subcutaneous tissue similar to technologies in the prior art. 
         [0005]    While the idea of such a simple insulin delivery device is compelling, many obstacles must be overcome before such a device may become a practical realty One problem resides in insulin supply. Patients vary greatly on the amount of insulin such a device must carry to provide treatment over a fixed time period of, for example, three days. This is one environment where one size does not fit all. Still further, such devices must be wearable with safety and not subject to possible accidental dosing. Still further, such devices must be capable of delivering an accurately controlled volume of medicament with reliability. While it is preferred that these devices include all of the forgoing features, it would be further preferred if the cost of manufacturing such a device would be economical enough so as to render the device disposable after use. As will be seen subsequently, the devices and methods described herein address these and other issues. 
       SUMMARY 
       [0006]    The invention provides a wearable infusion device for dispensing fluid such as a liquid medicine like insulin. In some embodiments of the invention, the device comprises a component that causes a piston to move an incremental distance and thereby cause a dose of medicament to be dispensed. The dose dispensed may be equal to a bolus of medicament, or it may be equal to a portion of a bolus. Thus, by moving the piston one or more incremental distances, the device may be used to service the bolus needs of a patient. 
         [0007]    The component may be an actuation component that includes an actuation pawl operable to engage a cog in a series of cogs of a drive component. In these embodiments the incremental distance may be the distance between adjacent cogs in the series of cogs, or the distance between two or more cogs in the series of cogs. Thus, the device may be easily used to provide boluses having different amounts of medicament which allows a single device to be easily used by a multitude of people, each requiring a bolus having a different amount of medicament. 
         [0008]    In other embodiments of the invention a wearable infusion device comprises a reservoir to hold more than one dose of a medicament; a piston moveable to cause a dose of the medicament to he dispensed; a drive component to cause the piston to move; and an actuation component to limit the distance that the piston moves for each dose dispensed to control the size of the dose. 
         [0009]    The drive component may rotate relative to the piston to move the piston. The drive component may also include a thread that engages a thread of the piston and that exerts pressure on the piston&#39;s thread when the drive component is rotated relative to the piston. 
         [0010]    The actuation component may be operable to rotate the drive component a first incremental distance to cause the device to provide the dose. The actuation component may also include a button that can be moved to cause the drive component to rotate, and a release biased toward a prevent position and movable to a release position, wherein when the release is in the prevent position, the release prevents the button from moving, and when the release is in the release position, the release allows the button to move. In these embodiments, the button and release may be pinched to rotate the drive component. 
         [0011]    In still other embodiments, the device may include a lockout component to prevent the piston from moving in a direction that does not cause the medicament to be dispensed, and to lock the piston when the piston reaches its maximum stroke. The lockout component may include a lockout pawl that engages a cog of the drive component to confine movement of the drive component to the direction that causes the device to dispense a dose of fluid, and that engages a slot to lock the drive component&#39;s movement when the piston reaches its maximum stoke. 
         [0012]    In yet other embodiments of the invention, a wearable infusion device comprises a reservoir for holding fluid to be dispensed, the reservoir being defined by a fixed wall and a side wall extending away from the fixed wall; and a piston disposed in the reservoir and movable relative to the fixed wall to exert pressure on the fluid. The device also comprises a drive component that engages the piston and is operable to move the piston toward the fixed wall, the drive component positioned relative to the piston such that the side wall lies between the drive component and the piston. The device also comprises an output interface in fluid communication with the reservoir. 
         [0013]    With the side wall lying between the drive component and the piston, the device can be made small enough to be worn directly on the skin under normal clothing at a location such as the abdomen, without causing discomfort, inconvenience, or creating a hazard, and can thus be used to provide a routine interstitial bolus injection of insulin. 
         [0014]    The reservoir may have circular cross-section, and the fixed wall may include an inside surface that is convex relative to the piston. 
         [0015]    The piston may be movable toward the fixed wall without rotating relative to the fixed wall. The piston may also include three tabs, each having an end that the drive component engages, and each extending through a respective slot in the side wall to position the respective end for engagement by the drive component. 
         [0016]    The invention also provides a system for dispensing a fluid In some embodiments of the invention, the system comprises the device discussed elsewhere herein and a cannula subassembly having a cannula for delivering fluid beneath a patient&#39;s skin. The cannula subassembly may be releasably coupled to the output interface of the device and in fluid communication with the reservoir of the device. The output interface may include a needle that is inserted into the cannula subassembly when the device and cannula subassembly are coupled together. 
         [0017]    The invention also provides a method for dispensing fluid. In some embodiments of the invention, the method comprises holding the fluid in a reservoir defined by a fixed wall, a side wall extending from the fixed wall and a piston, exerting pressure on the fluid in the reservoir by moving a drive component to move the piston toward the fixed wall, wherein the drive component is positioned relative to the piston such the side wall lies between the drive component and the piston, and allowing fluid in the reservoir to flow through an output interface to reduce the pressure on the fluid in the reservoir. 
         [0018]    The activity of exerting pressure on the fluid in the reservoir may include rotating the drive component relative to the piston an incremental distance. The activity may also include moving the piston toward the fixed wall without rotating the piston relative to the fixed wall. The activity may also include rotating the drive component an incremental distance in a first direction and preventing the drive component from moving in a direction opposite the first direction. 
         [0019]    In other embodiments of the method, the method may include locking the drive component when the piston reaches its maximum stroke. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0020]    The invention, together with further features and advantages thereof, may best be understood by making reference to the following description taken in conjunction with the accompanying drawings, in the several figures of which like reference numerals identify identical elements, and wherein: 
           [0021]      FIG. 1  shows a top perspective view of an exemplary wearable infusion device.  FIG. 2  shows a bottom perspective view of the wearable infusion device of  FIG. 1 . 
           [0022]      FIG. 3  shows an exploded, cross-sectional view of a portion of the wearable infusion device of  FIG. 1 , along the plane indicated by the line  3 - 3  in  FIG. 1 . 
           [0023]      FIG. 4  shows a cross-sectional view (not exploded) of the wearable infusion device of  FIG. 1 , along the plane indicated by the line  3 - 3  in  FIG. 1 . 
           [0024]      FIG. 5  shows two components (not coupled) of the wearable infusion device, and fluid flow through a portion of the wearable infusion device in  FIG. 1 . 
           [0025]      FIG. 6  shows a top view of an exemplary actuation component included in the wearable infusion device of  FIG. 1 . 
           [0026]      FIG. 7  shows a top view of an exemplary lockout component included in the wearable infusion device of  FIG. 1 . 
           [0027]      FIG. 8  shows a cross-sectional view of an exemplary fill port included in the wearable infusion device of  FIG. 1 . 
       
    
    
     DESCRIPTION 
       [0028]    Referring now to  FIGS. 1 and 2 , they show a wearable infusion device  20  embodying the present invention. The assembly  20  is configured to be worn on a patient&#39;s skin and, when operated, provides a patient a bolus injection of any desired fluid, such as insulin for treating diabetes The assembly  20  is small enough to be worn directly on the skin under normal clothing at a location such as the abdomen, without causing discomfort, inconvenience, or creating a hazard. 
         [0029]    The wearable infusion device  20  includes a cannula subassembly  22  to deliver the fluid into a patient&#39;s body, and a source subassembly  24  to hold the fluid and supply the fluid to the cannula subassembly  22 . In some embodiments, the cannula subassembly  22  and the source subassembly  24  are initially separate units that are releasably coupled together to form the wearable infusion device  20 . In some of these embodiments, one mounts the cannula subassembly  22  to a patient&#39;s body before coupling the cannula subassembly  22  to the source assembly  24 . U.S. patent application Ser. No. 11/803,007, filed May 11, 2007 and titled INFUSION ASSEMBLY, which is hereby incorporated by reference for all of its teachings and disclosures, discusses in greater detail the cannula subassembly  22  and mounting the subassembly  22  to a patient. In other embodiments, the cannula subassembly  22  and source subassembly  24  are not separate units that must be mounted to each other to form the wearable infusion device  20 . 
         [0030]    As may be noted, the cannula subassembly  22  includes a cannula  26  projecting from a first or bottom surface  28  so that when the cannula subassembly  22  is mounted on a patient&#39;s skin, the cannula  26  projects to beneath the patient&#39;s skin. The surface  28  includes an adhesive coated portion  30  to permit the cannula subassembly  22  to adhere to a patient&#39;s skin. 
         [0031]    The source subassembly  24  similarly includes an adhesive coated bottom surface  32  that permits the source subassembly  24  to adhere to the patient&#39;s skin. It is to be particularly noted that, in accordance with one aspect of the present invention, the adhesive coating  30  of the cannula subassembly  22  is separate and independent from the adhesive coating  32  of the source subassembly  24  Hence, each may be independently adhered to the patient&#39;s skin. 
         [0032]    The source subassembly  24  includes a reservoir (not. shown in  FIGS. 1 and 2 , but shown in  FIGS. 3 and 4 ) to hold fluid, a piston  34  that caps the reservoir, and a drive component  36  to move the piston  34  relative to the reservoir. As discussed in greater detail in conjunction with  FIGS. 3 and 4 , when the drive component  36  moves the piston  34  toward the fluid in the reservoir (into the paper as shown in  FIG. 1  of this embodiment), the piston  34  exerts pressure on the fluid. In response to the pressure, some of the fluid flows through an outlet and conduit (not shown in  FIGS. 1 and 2  but shown in and discussed in greater detail in conjunction with  FIG. 5 ) toward the cannula subassembly  22 . 
         [0033]    The source subassembly  24  can also include a gauge that provides a patient with information relating to the amount. of fluid in the reservoir that is available for future delivery. In this and other embodiments, the drive component  36  includes markings  38  that, in combination with a mark  40  on a wall  42  of the reservoir, show a patient how full the reservoir is at all times, i.e. how many boluses remain available for future use Here, the marking  38  that is aligned with the mark  40 , reveals that there are either 150 units (1.5 cc) available for future delivery, or 0 units (0 cc) available depending on whether the wearable infusion device has been used. 
         [0034]    The source subassembly  24  also includes an actuation component  44  that moves the drive component  36  an incremental distance. In this and other embodiments the actuation component  44  rotates the drive component  36  clockwise as viewed in  FIG. 1 . In response, the drive component  36  moves the piston  34  an incremental distance, which may or may not be equal to the incremental distance that the drive component  36  is moved The piston  34  then exerts pressure on the fluid in the reservoir to dispense a dose. In this and other embodiments, the actuation component  44  includes a drive button  46  and a release button  48 . As discussed in greater detail in conjunction with  FIG. 6 , when a bolus of fluid is desired, one first moves the release button  48  to a release position and holds the button at this position. Then, to move the drive component  36  an incremental distance one moves the drive button  46  through its full stroke, i.e. until the button  46  won&#39;t move anymore. If the bolus desired is greater than the dose dispensed by moving the drive component  36  a single increment of distance, one can repeatedly move the drive button  46  to move the drive component  36  the required distance. When the release button  48  is not in the release position, the drive button  46  can not be moved to prevent accidental actuation of the device, and thus prevent accidental delivery of a dose 
         [0035]    As discussed in greater detail in conjunction with  FIG. 8 , the source subassembly  24  can also include a port  49  to fill the source subassembly  24  with fluid. This permits the source subassembly  24  to be filled with the desired fluid just before mounting the source subassembly  24  to a patient&#39;s skin. The port  49  also permits the source subassembly  24  to be reused, if desired. 
         [0036]      FIG. 3  shows an exploded, cross-sectional view of a portion of the wearable infusion device  20  ( FIG. 1 ), along the plane indicated by the line  3 - 3  in  FIG. 1 .  FIG. 4  shows a cross-sectional view (not exploded) of the wearable infusion device  20  ( FIG. 1 ), along the plane indicated by the line  3 - 3  in  FIG. 1 . As can be seen in  FIGS. 3 and 4 , the source subassembly  24  is configured to provide a low profile so that the wearable infusion device  20  can be easily held directly on the skin and under normal clothing at a desirable location such as the abdomen, without generating attention to the assembly  20  or a hazard, or without causing discomfort or inconvenience. 
         [0037]    As previously mentioned, the source subassembly  24  includes the piston  34 , the drive component  36 , and a reservoir  50  to hold fluid to be dispensed. The reservoir  50  is defined by a fixed wall  52  and a side wall  42 . In this and other embodiments, the fixed wall  52  is a bottom wall, and the piston  34  caps the reservoir  50  and is moved toward the bottom wall by the drive component  36  to exert pressure on the fluid  51  ( FIG. 4 ) that is held in the reservoir  50 . The bellows  53  ( FIG. 4 ) seals the interface between the piston  34  and the sidewall  42 . To keep the profile of the reservoir  50  low, the top surface  54  of the piston  34  remains even with or below the top surface  56  of the side wall  42 , and the top surface of the drive component  36  also remains even with or below the top surface  56  of the side wall  42 . Thus, the sidewall  42  lies between the piston  34  and the drive component  36 . 
         [0038]    The drive component  36  can engage the piston  34  in any desired manner to move the piston relative to the fixed wall  52 . In this and other embodiments, the piston  34  includes threads  58 , and the drive component  36  includes threads  60  that threadingly engage the piston&#39;s threads  58 . The piston&#39;s threads  58  are located at the end of a tab  62  (three shown in  FIG. 1  but only one shown in  FIGS. 3 and 4 ) that extends through a respective slot  64  (three shown in  FIG. 1  but only two shown in  FIG. 3 ). The slots  64  are configured to confine the piston&#39;s movement to two directions—toward or away from the fixed wall  52 . Thus, when the drive component rotates around the sidewall  42 , the drive component&#39;s threads  60  exert pressure on the piston&#39;s threads  58  and thereby move the piston  34  toward the fixed wall  52 . 
         [0039]    The reservoir  50 , piston  34  and drive component  36  can be configured as desired to provide any desired dose per incremental distance that the piston  34  is moved. In this and other embodiments, the dose amount dispensed is a function of the incremental distance that the piston  34  moves multiplied by the projected area of the piston&#39;s surface  66  onto a plane oriented perpendicular to the direction of the piston&#39;s movement. Therefore, to generate a large dose the diameter of the piston&#39;s projected area can be increased, the length of the incremental distance can be increased, or both. Similarly, to generate a small dose the diameter of the piston&#39;s projected area can be decreased, the length of the incremental distance can be decreased, or both. In this and other embodiments, the length of the incremental distance can be increased or decreased by increasing or decreasing, respectively, the pitch of the threads  58  and  60 . In this manner, the source subassembly  24  can be configured to provide a dose that is equivalent to a desired bolus, and thus a patient need only move the drive button  46  once to obtain the desired bolus. 
         [0040]      FIG. 5  shows a view of the cannula subassembly  22  and the output interface  68  of the source subassembly  24  separate from each other.  FIG. 5  also shows the fluid flow from the reservoir  50  to the output interface  68 . As previously mentioned, in this and other embodiments the cannula subassembly  22  is releasably coupled to the source subassembly  24  via the output interface  68 . 
         [0041]    The output interface  68 , in this and other embodiments, includes a needle  70 , and an annular ring  72  configured to nest in the detent  74  of the cannula subassembly  22 , when the subassembly  24  is inserted into the output interface  68   
         [0042]    To releasably couple the cannula subassembly  22  with the output interface  68 , the cannula subassembly  22  is first aligned with and inserted into the output interface  68 ., As the cannula subassembly  22  is inserted into the output interface  68 , the needle  70  pierces the septum  76  of the cannula subassembly  22 , and the annular ring  72  enters the detent  74  of the cannula subassembly  22 . When the cannula subassembly  22  is fully inserted within the output interface  68 , the needle  70  has established fluid communication with the cannula  26 , and the annular ring  72  nests within the detent  74  to hold the cannula subassembly  22  to the output interface  68 . With fluid communication established between the needle  70  and cannula  26 , fluid  76  in the reservoir  50  can flow through the outlet  78 , through the conduit  80 , through the needle  70 , and through the cannula  26  to enter a patient&#39;s body. To separate the cannula subassembly  22  from the output interface  68 , one exerts force on the cannula subassembly  22  until the annular ring  72 , the detent  74 , or both, sufficiently deform to allow the cannula subassembly  22  to be withdrawn from the output interface  68 . 
         [0043]      FIG. 6  shows a top view of an exemplary actuation component included in the wearable infusion device of  FIG. 1 . As previously mentioned, the actuation component  44  moves the drive component  36  an incremental distance, which may or may not be equal to the incremental distance that the piston  34  ( FIGS. 1 ,  3  and  4 ) moves in the reservoir  50  ( FIG. 3 ). 
         [0044]    In this and other embodiments the actuation component  44  includes a drive button  46  having an actuation pawl  84 . The drive button  46  is configured to move in two directions  88  and  90  relative to the body  92  of the source subassembly  24 . When the drive button  48  moves in the direction  88 , the actuation pawl  84  exerts pressure on a contact surface  94  of a cog  95  disposed on the drive component  36 . The pressure causes the drive component to rotate (clockwise as shown in  FIG. 6 ), which in turn causes the piston  34  to move in the reservoir  50 . When the drive button  46  moves in the direction  90 , the actuation pawl  84  slides past an adjacent cog  96  and is positioned to exert pressure on the contact surface  97  of cog  96  when the drive button is again moved in the direction  88 . A spring  94  urges the drive button  46  to move in the direction  90 , and the shoulders  98  prevent the drive button from moving too far in this direction. An end wall  100  in the body  92  prevents the drive button from moving too far in the direction  88 . The full stroke of the drive component  46  is the movement of the drive component  46  from the position shown in  FIG. 6  to the position where an end  102  of the drive component  46  contacts the end wall  100 . 
         [0045]    As can be seen from  FIG. 6 , the drive button  46  and the drive component  36  are configured to engage each other such that moving the drive button  46  through its full stroke causes the drive component  36  to rotate the distance between the contact surfaces  94  and  97  of adjacent cogs  95  and  96 , respectively. Thus, in this embodiment, the incremental distance traveled by the drive component  46  is the distance between contact surfaces of adjacent cogs. In other embodiments, the drive component  36  can include more cogs on the periphery of the drive component  36  to allow a patient more control over the dose provided by a single movement of the drive button  46  For example, if the drive component  36  shown in the figures had twice as many cogs, the incremental distance traveled by the drive component  36  would remain the same but would comprise the distance between the contact surface of every other cog. Therefore, a patient could move the drive button  46  through half of its full stroke to inject a small dose of fluid, or through the drive button&#39;s full stroke to inject a larger dose. 
         [0046]    The actuation component  44  also includes a release button  48  that must be moved from a prevent position (shown in  FIG. 6 ) to a release position (not shown) before a patient can move the drive button  46  to dispense a dose of fluid. In this and other embodiments, the release button  48  includes an end  104 , and is pivotally attached to the body  92 . In the prevent position, the end  104  contacts the end  102  of the drive button  46  to prevent the drive button from being moved in the direction  88 . To move the release button  48  to the release position, a patient rotates the release button in the direction  106 . To urge the release button  48  toward the prevent position, a spring (not shown) is disposed between the release button  48  and the body  92 . 
         [0047]    In this and other embodiments, the drive button  46  and the release button  48  are arranged relative to each other to allow a patient to pinch the two buttons  46  and  48  to move the drive component  36 . Pinching allows a patient to create and quickly release a compressive force to generate a snapping movement of the drive button  46 , and thus help insure that the drive button  46  is moved through its full stroke. 
         [0048]      FIG. 7  is a top view of a portion of the wearable infusion device  20  ( FIG. 1 ) that shows an exemplary lockout component  110 . The lockout component  110  helps the actuation component  44  restrict the movement of the drive component  36  to a direction (clockwise as shown in  FIG. 7 ) that causes fluid to be dispensed from the source. The lockout component  110  also locks the drive component  36  when the piston  34  reaches the piston&#39;s maximum stroke, i.e. the position relative to the fixed wall  52  ( FIGS. 3 and 4 ) of the reservoir  50  ( FIG. 3 ) that the piston  34  does not cross to exert pressure on the fluid. When the piston  34  reaches its maximum stroke, the source subassembly  24  can not dispense another dose and is in effect empty. Thus, the locking of the drive component  36  can represent an empty condition of the source subassembly  24 . When locked, the drive component  36  can not move to advance or to withdraw the piston relative to the fixed wall  52 . 
         [0049]    In this and other embodiments, the lockout component.  110  includes a lockout pawl  112  nested in a receptacle  114  in the body  92  of the source subassembly  24 . The lockout pawl  112  includes an end  116  that contacts a cog  118 , and the receptacle  114  is configured to allow a portion  120  of the lockout pawl  112  to move relative to the remainder of the lockout pawl  112 . As the drive component  36  rotates (clockwise as show in  FIG. 7 ), the end  116  slides relative to the cog  118 , and the cog  118  exerts pressure on the end  116 . In response to this pressure, the lockout pawl  112  elastically deforms in the receptacle  114  and thereby permits the end  116  to move (to the right as shown in  FIG. 7 ). By elastically deforming, the lockout pawl  112  can remain in contact with the drive component  36  as successive cogs pass the end  116 , and can insert the end  116  into the slot  122  when the slot  122  is aligned with the end  116  to lock the drive component  36 . 
         [0050]      FIG. 8  is a cross-sectional view of a portion of the source subassembly  24  of  FIG. 1  that shows an exemplary fill port  49 . The fill port  49  permits the source assembly  24  to be filled with the desired fluid just before mounting the source assembly  24  to a patient&#39;s skin. The port  49  also permits the source assembly  24  to be reused, if desired. 
         [0051]    In this and other embodiments, the fill port  49  includes a septum  130  that a needle can pierce to inject fluid  76  into the reservoir  50  and that can seal the reservoir after the needle is withdrawn. A cover  132  is configured to be snapped into the opening  134  of the fill port  49  to protect the septum  130 . 
         [0052]    While particular embodiments of the present invention have been shown and described, modifications may be made, and it is therefore intended in the appended claims to cover all such changes and modifications which fall within the true spirit and scope of the invention as defined by those claims.