Patent Publication Number: US-9844635-B2

Title: Adjustable height needle infusion device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a division of a U.S. patent application of Ryan Schoonmaker et al. entitled “Adjustable Height Needle Infusion Device”, Ser. No. 13/303,055, filed Nov. 22, 2011, which issued Aug. 5, 2014 as U.S. Pat. No. 8,795,230, and which claims the benefit under 35 U.S.C. §119(e) of a U.S. provisional patent application of Ryan Schoonmaker et al. entitled “Adjustable Height Needle Infusion Device”, Ser. No. 61/344,971, filed on Nov. 30, 2010, the entire content of both of said prior applications being incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to components and elements of infusion sets, including a retraction dial for an infusion set, which ensures proper positioning of needle insertion by removably coupling with an infusion set and allowing a user to adjust a final needle depth by turning the dial. 
     BACKGROUND OF THE INVENTION 
     A large number of people, including those suffering from conditions such as diabetes use some form of infusion therapy, such as daily insulin infusions to maintain close control of their glucose levels. There are two principal modes of daily insulin. therapy. The first mode includes syringes and insulin pens. These devices are simple to use and are relatively low in cost, but they require a needle stick at each injection, typically three to four times per day. The second mode includes infusion pump therapy, which entails the purchase of an insulin pump that lasts for about three years. The initial cost of the pump can be significant, but from a user perspective, the overwhelming majority of patients Who have used pumps prefer to remain with pumps for the rest of their lives. This is because infusion pumps, although more complex than syringes and pens, offer the advantages of continuous infusion of insulin, precision dosing and programmable delivery schedules. This results in closer blood glucose control and an improved feeling of wellness. 
     The use of an infusion pump requires the use of a disposable component, typically referred to as an infusion set or pump set, which conveys the insulin from a reservoir within the pump into the skin of the user. An infusion set typically consists of a pump connector, a length of tubing, and a hub or base from which an infusion needle or cannula extends. The hub or base has an adhesive which retains the base on the skin surface during use, and may be applied to the skin manually or with the aid of a manual or automatic insertion device. 
     Currently, most insulin infusion sets deliver insulin to the sub-cutaneous layers of skin using either fixed metal needles or flexible plastic cannulas. Such infusion sets typically deliver insulin 4-10 mm below the skin surface. However, the upper 3 mm of skin surface, the intradermal space, facilitates better drug absorption. Unfortunately, due to the, relative, thinness of the intradermal layer, inserting a needle at such depth and maintaining an infusion site over an extended period of time within this narrow band is difficult. 
     Further, most insulin infusion sets typically do not provide any features to isolate the inserted needle from shock or other external forces. Since these infusion sets typically deliver insulin 4-10 mm below the skin surface, shock or other external forces to the set have less effect on the deeper inserted needle. However, where an attempt is made to target the upper 3 mm of skin surface, any shock or movement of the set can adversely affect needle insertion and infusion performance. 
     Still further, most insulin sets have inserters that can result in skin surface “tenting” during needle insertion, where the skin surface is deflected somewhat prior to or during needle insertion, which makes precisely targeting the upper 3 mm of skin surface difficult. 
     Accordingly, a need exists for advanced, improved, and novel components and elements of current and future infusion sets that can deliver content to the upper 3 mm of skin surface, the intradermal space, to facilitate better drug absorption, while maintaining a degree of comfort to the user. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide an infusion set which can deliver insulin or other medicament to the upper 3 mm of skin surface, the intradermal space, to facilitate better drug absorption, while maintaining a degree of comfort to the user. 
     Another object of the present invention is to provide an infusion set having an inserter that can insert a needle which can be removed from the infusion set after insertion. 
     Another object of the present invention is to provide an infusion set with a removable retraction dial on its upper surface, wherein the retraction dial can be used to precisely retract an inserted needle to reach a desired depth to deliver insulin or other medicament to the upper 3 mm of skin surface, or retract an inserter needle some distance into a soft cannula after insertion. 
     Another object of the present invention is to provide an infusion set that includes a needle hub in a threaded engagement with a main base, such that rotation of the needle hub relative to the main base results in retraction or advancement of a needle of the needle hub. 
     Another object of the present invention is to provide an infusion set with the removable retraction dial to rotate the needle hub relative to the main base to precisely retract an inserted needle to reach a desired depth to deliver insulin or other medicament to the upper 3 mm of skin surface. 
     Another object of the present invention is to provide an infusion set that can isolate an inserted needle from external forces such that the needle can he maintained at a depth to deliver insulin or other medicament to the upper 3 mm of skin surface during normal use. 
     These and other objects are substantially achieved by providing an infusion set having a retraction dial that can be removably assembled with the infusion set and access a threaded needle hub contained therein such that the dial can be used to advance or retract an inserted needle to a depth to deliver insulin or other medicament to the upper 3 mm of skin surface, or retract an inserter needle some distance into a soft cannula after insertion. Position of the inserted needle can be maintained by providing a needle hub, main base and main hub of the infusion set that can isolate the inserted needle from external forces such that the needle can be maintained at a depth to deliver insulin or other medicament to the upper 3 mm of skin surface during normal use. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The various objects, advantages and novel features of the exemplary embodiments of the present invention will be more readily appreciated from the following detailed description when read in conjunction with the appended drawings, in which: 
         FIG. 1  is a perspective view of an infusion set in accordance with an embodiment of the present invention; 
         FIG. 2  is a bottom perspective view of the infusion set of  FIG. 1 ; 
         FIG. 3  is a cross-sectional view of the infusion set of  FIG. 1  showing the needle in an inserted position, but prior to user retraction, in accordance with an embodiment of the present invention; 
         FIG. 4  is a bottom perspective view of the infusion set of  FIG. 1  shown without an adhesive layer for illustrative purposes in accordance with an embodiment of the present invention; 
         FIG. 5  is a top perspective view of the infusion set of  FIG. 1  with the retraction dial removed in accordance with an embodiment of the present invention; 
         FIG. 6  is a bottom perspective view of the infusion set of  FIG. 1  illustrating a soft cannula insertion in accordance with an embodiment of the present invention; and 
         FIG. 7  is a top perspective view of the infusion set of  FIG. 1  with the retraction dial removed and the infusion pump tube connection in place in accordance with an embodiment of the present invention. 
     
    
    
     Throughout the drawings, like reference numerals will be understood to refer to like parts, components and structures. 
     DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS 
     The exemplary embodiments of the present invention described below provide a novel means of delivering insulin to the intradermal layers of skin via a standard insulin pump. In particular, the exemplary embodiments of the present invention provide an infusion set with a retraction dial to advance or retract an inserted needle to deliver insulin to the upper 3 mm of skin surface, the intradermal space, to facilitate better drug absorption, while maintaining a degree of comfort to the user. 
     As will be appreciated by one skilled in the art, there are numerous ways of carrying out the examples, improvements and arrangements of insulin-associated devices disclosed herein. Although reference will be made to the exemplary embodiments depicted in the drawings and the following description, the embodiments disclosed herein are not meant to he exhaustive of the various alternative designs and embodiments that are encompassed by the disclosed invention. 
     As noted, the exemplary embodiments of the present invention deliver insulin to the intradermal layers of the skin via a standard insulin pump or other similar device. By utilizing a refraction dial, and an isolated needle hub, proper insertion and maintenance of the inserted needle in the intradermal space is ensured. Position of the inserted needle can be maintained by providing a needle hub, main base and main hub of the infusion set, and tube attachment, that can isolate the inserted needle from external forces such that the desired needle depth can be maintained. 
     Proper needle insertion stands as a primary obstacle to infusing insulin via a pump into the intradermal layer. In the exemplary embodiments of the present invention, the initial insertion of the needle is substantially the same as performed using any standard infusion set, but a removable retraction dial is provided to advance or retract the inserted needle, or retract an inserter needle some distance into a soft cannula after insertion. By retracting the inserted needle a slight distance, medicament can be delivered into the thin intradermal layer. Utilizing precision parts, this process can be reliable when compared to a standard manual intradermal injection procedure, such as the Mantoux technique. 
     However, maintaining the position of the needle within the intradermal layers of the skin over the course of a typical three-day period poses significant technical challenges. Accordingly, the exemplary embodiments of the present invention further provide at least two methods of anchoring the needle in place. First, the main base of the device creates and maintains a preload on the skin surface, which locks the needle in place vertically. Second, an adhesive may be applied to the main base in the area of the needle, locking the skin surface to the needle location. 
       FIGS. 1 and 2  are perspective views of an infusion. set in accordance with an embodiment of the present invention. As shown in  FIGS. 1-3 , the exemplary infusion set  10  can comprise an outer hub  12 , main hub  14 , main base  16 , needle hub  18 , and retraction dial  20 . An outer ring  22  rotatably extends between the outer hub  12  and retraction dial  20 . The hub, base and other elements can be constructed of a molded plastic material, polycarbonate, thermoplastic polymer such as polyethylene terephthalate (PET and PETG), or similar materials. 
     As shown in greater detail in  FIGS. 2 and 3 , the needle hub  18  is positioned within the main base  16 , and comprises a needle  24 . The main base  16  contains the needle hub  18  and an optional needle hub adhesive layer  26 . A main base inner adhesive layer  28  can also be provided on the main base  16 , and an outer hub adhesive layer  30  can be provided on the outer hub  12 . 
     The needle hub  18  is held within an opening of the main base  16  via a helical threaded engagement between the needle hub  18  and the main base  16 . A female thread groove  17  in the wall of opening  38  receives a male thread  19  on the needle hub  18 . In doing so, rotation of the needle hub  18  within the opening  38  of the main base  16  serves to advance or retract the needle hub  18  via the threaded engagement, within the opening  38  of the main base  16 , thereby advancing or retracting the needle  24  relative to the main base  16  adhered to the skin surface. 
     The main hub  14  rotatably covers the main base  16  and provides a fluid communication channel  52  between an inner septum  32  and a valve connection septum  34 . The main hub  14  is held in place by the flexible tube connection  48  between the main hub  14  and the outer ring  22 , as shown in  FIG. 4 , and by the geometry of the main base  16  and the outer ring  22 . As illustrated in  FIG. 3 , the needle  24  comprises first and second ends, wherein the first end is configured to penetrate a skin surface (not shown), and the second end (which may be sharpened or unsharpened) is configured to penetrate an inner septum  32  (which may be pre-slit and/or pierceable) as described in greater detail below. The inner septum  32  is held within a protrusion  36  of the main hub  14 , which is configured to slidably engage a similarly shaped opening  54  in the needle hub  18  as the needle hub is advanced or retracted. The needle  24  can comprise a  31  gauge,  3  mm in length, single-bevel stainless steel needle/cannula, but is not limited thereto. In other embodiments of the present invention, the needle  24  can be plastic or other material, between 27 gauge and 34 gauge, between 2 mm and 5 mm in length, and be provided with a tri-bevel or 5-bevel needle. The needle  24  can be bonded to the needle hub  18  with an adhesive, such as a Loctite/UV cured adhesive, or can be over molded with, or threaded into, the needle hub. Further, other embodiments of the present invention, the needle  24  can be replaced with a soft cannula provided with an internal introducer needle that can be retracted inside the soft cannula. The needle  24  can also comprise a needle longer than that used to simply target the intradermal layer, since the needle of the exemplary embodiments of the present invention is first inserted to a depth of, for example, 5 mm to 6 mm, and then retracted to the targeted intradermal depth of for example, 3 mm or less, As described in greater detail below, this allows use of a longer needle, minimizes the risk of tenting or skin deflection affecting the final insertion depth, and creates an opening to minimize pressure. 
     The example shown in  FIG. 3  illustrates an infusion set wherein the needle  24  has been inserted (or, in the case of a soft cannula and internal introducer needle, wherein the soft cannula and introducer needle have been inserted), and the retraction dial  20  exposed. The retraction dial  20  comprises at least one member  40  extending through an opening  56  of the main hub  14  and terminating in an opening  58  of the needle hub  18  to transmit a rotary force thereto. 
     The retraction dial  20  is configured to cover the main hub  14  and main base  16  to permit user adjustment of the needle  24  depth. To do so, the retraction dial  20  comprises the least one member  40  extending through the opening  56  of the main hub  14  and terminating in the opening  58  of the needle hub  18 . Accordingly, when the retraction dial  20  and member  40  are turned, the main hub  14  and needle hub  18  are turned with the retraction dial  20 . However, the main base  16  remains stationary, in adhesive contact with the skin surface. Accordingly, as the needle hub  18  is rotated by the member  40 , the threaded engagement with the stationary main base  16  results in an upward or downward movement of the needle hub  18  and the attached needle  24  (or, in the case of a soft cannula and internal introducer needle, results in the introducer needle being retracted or advanced inside the soft cannula). 
     Accordingly, by turning the retraction dial  20 , a user can retract (i.e., move upward) the needle  24 . In doing so, a desired depth of needle penetration can be achieved more precisely. Further, the passageway initially created by the fully inserted needle, results in an opening or unfilled passageway as the needle  24  is slightly retracted. The benefits associated with infusion to this additional unfilled passageway are described below. Still further, as the needle  24  is retracted, the second end of the needle  24  contacts and pierces the inner septum  32 , such that the needle  24  is in fluid communication with the channel  52  of the main hub  14 . 
     The retraction dial  20  is further configured to simply pull free from the main hub  14  and main base  16  after the desired retraction, as the member  40  is simply held in place by friction engagement with the through-openings  56  and  58 , and the opening  60  between the main hub  14  and outer ring  22 . Accordingly, upon reaching the desired retraction depth, which can be denoted by a positive stop or some other user-detectable feature, the retraction dial  20  can be removed, thereby leaving the device as shown in  FIG. 5 . The retraction dial  20  can be marked to denote needle depth, or can be configured to release from the infusion set when the needle reaches a desired depth (i.e. about one rotation or 360 degrees). Still further, it may be desirable to retain the retraction dial  20  in place for later needle height adjustments. By allowing the user to make minute adjustments to the needle height within the intradermal layer, tissue tolerance of infusion may increase. Also, occlusions caused by foreign body response at the end of the needle may be released by these movements. Such a height adjustment feature is easy to adjust in small increments, yet difficult to move accidentally. A release button (not shown) can also be provided. it can also be possible to allow the user to selectively adjust the height to either a subcutaneous or intradermal height setting. 
     In yet another exemplary embodiment of the present invention shown in  FIG. 6 , an internal introducer needle  124  can be used to insert a soft cannula  126 , and then be partially retracted or withdrawn a distance into the cannula using the retraction dial  20 . In this case, the retraction dial  20  can be used to control a distance the introducer needle is withdrawn into the cannula, and subsequently, to control the length of flexible cannula free of the introducer needle. For example, the device can be used to insert the soft cannula  126  and the retraction dial  20  can be used to retract or withdraw the introducer needle  124  some distance back into the soft cannula. The soft cannula can comprise Teflon or Vialon, and be between 25 gauge and 32 gauge. In such an exemplary embodiment, a steel introducer needle can be provided and be between 27 gauge and 34 gauge for proper fitting inside the soft cannula. 
     At this time, the infusion pump tube attachment  42  and tubing  44  to the infusion pump (not shown) can be attached to the top of the infusion set as shown in  FIG. 7 .  FIG. 7  is a top perspective view of the infusion set of  FIG. 1  with the retraction dial removed and the infusion pump tube connection in place. The infusion pump tube attachment  42  comprises a circular cover piece to which the tubing  44  is attached and routed through to a septum piercing member (not shown) to engage and pierce the valve connection septum  34 . Alignment between the infusion pump tube attachment  42  and the valve connection septum  34  is achieved through the engagement with the self-alignment features, or slots,  46  in the outer ring  22 . For example, an inner surface of the cover piece of the infusion pump tube attachment  42  can comprise one or more projections or boss features (not shown) which mate with the slots  46  to thereby allow complete downward assembly of the infusion pump tube attachment  42  with the infusion set when the valve connection septum  34  is in alignment for piercing. 
     In addition, the infusion pump tube attachment  42  is free to rotate 360 degrees, allowing the tubing  44  to the pump to be arranged in a comfortable orientation. To do so, the outer ring  22  to which the tube attachment  42  is secured, is rotatable between the outer hub  12  and the main hub  14 . Specifically, the outer ring  22  of the device is configured to be rotatable along track-like features  62  in the outer hub  12 , which is fixed to the user&#39;s skin surface. By connecting the outer hub  12  and the outer ring  22  via the track features  62 , and connecting the outer ring  22  to the main hub  14  via the thin flexible length of tubing  48 , the outer ring  22  and valve connection septum  34  can rotate as permitted by the flexible tubing  48 , In doing so, the infusion pump tube attachment  42  is permitted to rotate. In the exemplary embodiment shown, the flexible tubing  48  at least partially encircles the main hub  14  and main base  16 , which permits a shorter or flatter device profile. 
     Vibrational and shock isolation of the main hub  14  and main base  16 , from the outer hub  12 , outer ring  22  and valve connection septum  34 , is achieved in a number of ways, including the provision of the track features  62  between the outer hub  12  and the outer ring  22 , and the flexible tubing  48  between the fluid channel  52  of the main hub  14  and connection valve  50  of the outer ring  22 . Further, once the retraction dial  20  is removed, the main hub  14  and main base  16  are separated from the outer hub  12  and outer ring  22 . That is, first, the main hub  14  and the outer ring  22  are physically separated and are connected only by the flexible tubing  48 , and second, the main hub  14  and main base  16  are secured to the skin surface via adhesive layers  26  and  28 , and the outer hub  12  is secured to the skin surface via adhesive layer  30 , wherein the layers  26 ,  28  and  30  are physically separated. In doing so, the only connection between the main hub  14  and main base  16 , and the outer hub  12  and outer ring  22  (and the attached infusion pump tube attachment  42 ), is the flexible tubing  48 . Further, once covered by the tube attachment described in greater detail below, external contact with the main hub  14  and main base  16  is prevented. 
     The exemplary embodiments of the present invention provide a novel means of delivering insulin to the intradermal layers of skin via standard insulin pumps, but are not limited thereto. The invention can also be applied to patch pumps or other infusion devices. 
     Further, the exemplary embodiments comprise a straight microneedle, needle, or other cannula, that can be inserted by the user into the deeper dermis or the subcutaneous layers of the skin, and can then be withdrawn with a great deal of precision into the dermal layer, where it is held by adhesive and/or mechanical preload. 
     Initial insertion of the infusion set with a user controllable needle depth is similar to the operation of fixed steel cannula devices currently on the market. The user first peels off a flexible backing, removes a needle cover, and then inserts the needle into the infusion site. After ensuring good skin adhesion, the user then turns the retraction dial. The retraction dial can be marked to denote needle depth, reach a positive stop, or can be configured to release from the infusion set when the needle reaches a desired depth (i.e. about one rotation or 360 degrees). In an exemplary embodiment, the retraction dial is configured to turn a quarter turn (i.e., 90 degrees) to reach the desired depth. The user can then remove the retraction dial and attach the pump tube attachment, in the case of an infusion set, from the top of the device. The device is then ready to prime and deliver insulin. In addition, the valve connection is free to rotate up to 360 degrees, allowing the tubing to the pump to be arranged in a comfortable orientation. 
     As the retraction dial  20  turns, the needle  24  and needle -hub  18  of the device move up the threaded engagement  17  and  19  located in the main base  16 . The needle  24  protrudes from both sides of the needle hub  18  and, on the side opposite the side that pierces the skin, the needle  24  pierces through the inner septum  32  as it moves upward, establishing fluid communication with the valve connection interface. As the needle  24  pierces the inner septum  32  in such a manner, it can be locked in place with respect to the main base  16 . To do so, a detent or projection not shown) can be provided on an outer surface of the needle hub  18  that is configured to mate with a similar detent or projection (not shown) provided on an inner surface of the main base  16  when the needle hub  18  reaches the desired position. Once engaged, the detents can lock the needle hub  18  in place with the main base  16 . The fluid path  30  is open through the main hub  14  and the flexible piece of tubing  48  which leads to the valve connection septum  34  located in the outer ring  22 , which is able to rotate about the main hub  14  and main base  16  as permitted by the track in the outer hub  12  and tubing  48 . 
     As shown in  FIG. 3 , the main base  16  also provides a contour on a lower surface that contacts the skin surface around the needle  24 , providing a slight preload, or indentation, on the skin surface which helps maintain the needle position within the intradermal layer. In addition, adhesive layer  26  can be placed on the main base  16  in the vicinity of the needle  24  to help with the anchoring of the needle in the skin surface. 
     The outer ring  22  of the device is configured to be rotatable along the track-like features  62  in the outer hub  12 , which is fixed to the user&#39;s skin surface. By connecting the outer hub  12  and the outer ring  22 , to the main hub  14  and main base  16 , via the thin flexible length of tubing  48 , external forces and vibrations are absorbed by the outer hub  12  and the outer ring  22 , but not by the main hub  14 , main base  16 , needle hub  18  and the needle  24 . Finally, the infusion pump tube attachment  42  can be attached to the outer ring  22 , covering the assembly and providing further isolation of the needle, and the self-centering features of slots  46  ensure that the valve connection needle (not shown) pierces the valve connection septum  34 . 
     As noted above, the passageway initially created by the fully inserted needle, results in an opening or unfilled passageway as the needle  24  is slightly retracted. As known in the art, high pumping pressure (i.e., 20-50 or more psi), can occur during intradermal infusion. However, by first providing the deeper insertion tunnel established by the initial insertion depth as recited above, and the subsequent withdrawal to the infradermal layer, embodiments of the present invention can relieve such pressures by increasing the surface area of the deposition area. 
     Further, by infusing into the intradermal layer of the skin, the exemplary embodiments of the present invention offer the potential for better absorption of insulin when compared to subcutaneous delivery systems. In doing so, it may be possible for the typical user to both consume less insulin and maintain a better medicament regime. 
     Other intradermal infusion set concepts are at risk of “tenting”, which is the undesired effect where skin is deflected at needle insertion before or during insertion, creating a shape similar to a tent. In doing so, the skin surface tents during needle insertion rather than needle penetration into the skin. However, since a longer needle can be used, and then slightly retracted in the exemplary embodiments of the present invention, the risk of tenting or skin deflection otherwise affecting final insertion depth is reduced. Still further, a small intradermal needle placed perpendicular to the skin and isolated from outside forces causes less pain to the user during use. 
     In current steel cannula, infusion sets which deliver to the subcutaneous layer, the needle is not isolated from any undesired outside forces which may cause pain when translated to the needle and the needle moves within the skin. Also, other intradermal devices face problems of premature or otherwise undesired needle removal when the device is bumped, if the needle is not isolated from the outside forces. 
     In the exemplary embodiments of the present invention, the intradermal needle is isolated from outside forces by a cover design, a double ring feature, and the provision of flexible tubing. Such features help to effectively isolate the needle from the outside forces and other interferences. 
     By infusing into the intradermal layer of the skin, the exemplary embodiments of the present invention offer the potential for better absorption of the insulin when compared to subcutaneous delivery systems. It may be possible for the user to maintain a better medicament regimen while using less insulin. Further, the provision of a small intradermal needle placed perpendicular to the skin and isolated from outside forces causes less pain and discomfort to the user during use. 
     Although only a few exemplary embodiments of the present invention have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention as defined in the appended claims and their equivalents.