Abstract:
A manually operated medicament infusion device is provided. The device is capable of delivering an accurately controlled volume of medicament with reliability. Additionally, the device includes a battery-operated indication device for tracking the number of doses of medication delivered. Optionally, the device includes a ratchet and pawl to prevent inadvertent dispensing of medicament.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to infusion devices. More particularly, the invention relates to manual infusion devices that enable liquid medicaments to be conveniently and safely self-administered by a patient. The pump of the invention includes an indication device suitable for displaying dose information to the pump user. 
       BACKGROUND OF THE INVENTION 
       [0002]    Self-delivery of medicaments by patients dealing with temporary or chronic disease states has been enabled by use of portable, external infusion pumps. Use of these pumps has been shown to improve the quality of life as well as the general health of these patients. However, the size, cost, and complexity of these infusion pumps can be a drawbacks for the users. For example, some of the pumps are electronically controlled and must be programmed to supply the desired amounts of medicaments. This prevents many users from accepting the use of this technology. 
         [0003]    Hence, there is a need in the art for a convenient form of treatment using infusion pumps that do not require significant programming or technical skills to use. Preferably, such a treatment would be carried out by an infusion device that is simple to use and mechanically driven. 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 medicament would be preferably delivered through a small, thin-walled tubing or cannula through the skin similar to known technologies. 
         [0004]    Although the idea of such a simple delivery device is compelling, many obstacles must be overcome before such a device may become a practical realty. One problem resides in medicament supply. Patients vary greatly on the amount of medicament 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 safely wearable and not subject to possible accidental dosing. Still further, such devices must be capable of delivering an accurately controlled volume of medicament with reliability. Finally, a device that provides a means for tracking the number of doses of medication delivered is highly desirable to permit a patient or healthcare provider to ensure that the correct amount of medication is administered over a given period of time. 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. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]      FIG. 1  is a top perspective view of the device of the invention. 
           [0006]      FIG. 2  is a top perspective view of the device of  FIG. 1  with a portion of the housing removed. 
           [0007]      FIG. 3  is a side perspective view of the device of  FIG. 1  with a the housing represented by the dotted line with internal components of the device shown. 
           [0008]      FIG. 4  is a side perspective view of the device of  FIG. 1  with a portion of the housing removed. 
           [0009]      FIG. 5  is a side perspective view of gearing mechanism for the device of  FIG. 1 . 
           [0010]      FIG. 6  is a side perspective view of the gearing mechanism of  FIG. 5  with a piston and encoder. 
           [0011]      FIG. 7  is a side perspective view of the gearing mechanism, piston, and encoder of  FIG. 6  along with optical sensors. 
           [0012]      FIG. 8  is a side perspective view of a medicament cartridge useful in the device of  FIG. 1 . 
           [0013]      FIG. 9  is a side perspective view of cartridge of  FIG. 8  in a cartridge retainer. 
           [0014]      FIG. 10  is a side perspective view of the bottom surface of the cartridge retainer of  FIG. 9 . 
           [0015]      FIG. 11  is a top perspective view of the device of  FIG. 1  with a portion of the housing and the display removed. 
           [0016]      FIG. 12  is a top perspective view of the device of  FIG. 1  with a portion of the housing and components removed to show the leadscrew shaft and piston at full extension. 
           [0017]      FIG. 13  is a side perspective view of a rewind tool useful with the device of  FIG. 1 . 
           [0018]      FIG. 14  is a view of the rewind tool of  FIG. 13  shown in use with the device of  FIG. 12 . 
           [0019]      FIGS. 15A and 15B  are perspective views of a locking mechanism for the device of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0020]    Referring now to  FIG. 1 , a top perspective view of a first infusion device embodying certain aspects of the present invention is shown. The device  10  generally includes housing  11 , which housing includes indication device  12  within an opening in the housing. Drive wheel  13  is also shown. Indication device  12 , as shown, is a display that provides information regarding the medicament doses delivered by, and doses remaining in, device  10 . The display may depict numbers, words, icons or the like, but preferably is a single line, numerical display. Preferably, the display indicates the number of insulin units being delivered (shown in  FIG. 1  as “2.6”) by the device  10  and the number of medicament units remaining (shown in  FIG. 1  as “175”) within the device to be delivered. The indication device may be any known type of display such as an LCD, LED, OLED, but preferably is an OLED display. As shown in  FIG. 2 , a power source, such as a coin cell battery  15 , is provided within the device, which battery powers the display, as well as the sensors, microcontroller and associated circuits of the device described hereinbelow. Removable housing panel  14  of housing  11  shown in  FIG. 1 , provides access to the battery. Because the pumping mechanism of the infusion device of the invention is manually operated, the power required for the device is minimal. 
         [0021]    The infusion device of the invention includes a gearing mechanism that is manually operated. As shown in  FIG. 5 , in one embodiment, gearing mechanism  20  includes drive wheel  13  with gear  24  extending from a surface thereof. Although a drive wheel is shown, it will be understood that other simple, hand-operated components, capable of providing rotary motion may be used in place of the drive wheel. Gear  24  is designed to mesh with the threads, or gear teeth, of leadscrew base  16 , the rotation of which base turns threaded leadscrew shaft  25 . Rotation of drive wheel  13  correlates to leadscrew shaft  25  rotation via the enmeshment or gearing interaction of gear  24  with leadscrew base  16 . As shown in  FIGS. 3, 4, 6 and 7 , piston  17  with piston end  18  is movably affixed to leadscrew shaft  25 . As leadscrew shaft  25  is rotated by the gearing interaction of gear  24  with leadscrew base  16 , piston  17  indexes away (described in further detail hereinbelow), meaning moves farther in distance in a longitudinal direction away from leadscrew base  16  and along leadscrew shaft  25 . 
         [0022]    For delivery of medicament from the infusion device, small, precise movements of the leadscrew mechanism are desired. The amount of forward movement, or extension, of piston  17  may be directly calculated from the leadscrew pitch. By way of example, the leadscrew may be a #2-56 screw having 56 threads per inch and a gear ratio between the leadscrew base and threaded shaft may be a 4:1 ratio. In this case, one complete turn of drive wheel  13  correlates to a ¼ turn of leadscrew base  16  and a 0.0045 inch extension of piston  17 . Pressure fron the forward movement of piston end  18  drives a plunger in a medicament cartridge. Thus, if the volume of a medicament cartridge, into which the shaft  25  drives piston end  18 , is 0.44 units, this movement would result in infusion of 0.00070 cubic inches (0.11 ml; 1.1. units) of medicament to the user. 
         [0023]    Also included within housing  11  is a sensing mechanism. The sensing mechanism may be any known mechanism capable of electrically connecting to indication device  12 . As shown in  FIGS. 3 and 7 , the sensing mechanism includes a circuit board  24  that includes a microcontroller and display driver (not shown). Circuit board  24  also includes at least one sensor  22  affixed thereto. The sensors may be any sensor type, such as optical sensors, capable of measuring movement of the gears and the piston. As shown in  FIGS. 6 and 7 , a rotary encoder is used that includes rotary wheel  19 . Rotary wheel  19  may contain any desired number of slits or transitions for the optical sensors. Light from optical sensor  22 , for example, beamed perpendicular to rotary wheel  19  is either reflected back to a receiver in the sensor or passed through the sensor. The disruption in the beam caused by the slits is used by the sensor electronics to convert the light to electrical signals. For example, the wheel shown in  FIG. 6  will provide 10 voltage transitions (5 up and 5 down) resulting in emission of 10 signals per wheel revolution. If one revolution is 1.1 units of medicament, the display can depict those units in increments of about 0.1 units of medicament. 
         [0024]    Preferably, additionally provided are sensors for measuring the maximum extension and retraction of the piston  17 . These sensors, shown as  22 ′ and  22 ″ on circuit board  24  in  FIG. 7 , indicate when the medicament cartridge is empty or, as described hereinbelow, fully rewound. Piston  17  is made or coated with a reflective material that reflects beamed light back to the sensors. As the piston moves forward along the threaded shaft  25  and past a sensor, the light beam will not be reflected and provides an indication of the position of the piston. In the fully forward position, no reflection from the piston to either sensor  22 ′ or  22 ″ indicates that the piston is fully extended and, thus, has acted on a plunger within the medicament cartridge to empty the cartridge. 
         [0025]    Any known medicament cartridge suitable for storing the medicament to be used and capable of interacting with piston  17  to expel medicament may be useful with the device of the invention. Preferably, the medicament cartridge is a compact cartridge holding about 200 to about 300 units of medicament, which medicament preferably is insulin. For example, as shown in  FIG. 8 , cartridge  30  includes plunger  31  therein. One end of the cartridge, the infusion end, is suitable for connecting to a cannula, needle or the like for infusion of the substance into the user. As shown, infusion end  32  includes a threaded fitting suitable for, for example, connecting to a conventional luer-type connection. However, any suitable connection may be used for infusion end  32 . 
         [0026]    As shown in  FIGS. 9, 10 and 11 , within housing  11  is retainer  26  for holding cartridge  30  within the device.  FIG. 11  depicts cartridge  30  assembled in retainer  26  within housing  11 . As shown, retainer  26  is sized and shaped so that cartridge  30  may nest within one end of retainer  26  ( FIGS. 9 and 10 ) and piston  17  nests in an opposite end ( FIG. 11 ). Retainer  26  prevents piston  17  from rotating in response to leadscrew shaft  25  being rotated by the gearing interaction of gear  24  with leadscrew base  16 . Snap  23 , which is a flange integral with and extending from bottom surface  29  of retainer  26 , abuts surface  28  of housing  11  against which it is held. Depression of snap  23  allows retainer  26  to pass under surface  28  and permits its removal from, or insertion into, the housing along with cartridge  30 . Channel  27  within retainer  26 , shown in  FIG. 9 , provides for access to plunger  31  by piston  17  and piston end  18 . As piston  17  is extended by manual turning of wheel  13  and indexes along threaded shaft  25  and through channel  27  forcing piston end  18  to move plunger  31  resulting in expulsion of medicament from cartridge  30 . Piston  17  is shown with piston end  18  engaged with plunger  31  in  FIG. 11 . 
         [0027]    One feature of the device of the invention is the ability to manually rewind the piston on the leadscrew enabling reuse of the device once the medicament cartridge is empty.  FIG. 12  depicts housing  11  with an empty medicament cartridge and its retainer removed from the device and piston  17  is shown in its fully extended position along leadscrew shaft  25 . If manual returning of piston  17  to its retracted start position within the device was performed against the gearing mechanism, hundreds of turns of the piston would be required to overcome the gearing ratio and index the piston to its original position. With the device of the invention, removal of the retainer and use of a rewind tool  40 , shown in  FIGS. 13 and 14 , can be used to easily rewind the piston to its starting position. After cartridge  30  is emptied, retainer  26  along with the empty cartridge  30 , are removed from the device. Removal of retainer  26  allows for rotation of piston  17 . Rewind tool  40  includes turn handle  41 , wheel  43  that preferably is grooved, indented or the like therearound to facilitate gripping, shaft  42  and opening  44 . Opening  44  is sized and shaped to releasably engage piston end  18 .  FIG. 14  shows the rewind tool seated on the piston end. As the tool is turned in a clockwise direction, the piston rotates in a direction shown by arrow A resulting in indexing of the piston along shaft  25  in the direction indicated by arrow B. 
         [0028]    The device of the invention may be worn by an individual on a belt, in a pocket of other suitable clothing compartment. Thus, additionally a removable adhesive pad may be provided to removably affix the device to the user&#39;s body. Preferably, the device is compact and sized and shaped to be unobtrusively worn and is between about 2.8×0.1.0.×0.9 inches to about 3.5×1.7×1.6 inches. 
         [0029]    In one embodiment, a suitable locking mechanism that prevents the inadvertent forward indexing of piston  17  may be used. For example, and as shown in  FIGS. 15A and 15B , a ratchet  51  may be mounted on drive wheel  13 . In  FIG. 15A , drive wheel  13  is shown in dotted line form and positioned so that ratchet  51  lies underneath it. Ratchet  51  cannot turn unless sufficient force is imposed by the device user on drive wheel  13  for the teeth of ratchet  51  to push past pawl  52 , permitting rotation of the drive wheel and ultimately, medicament dispensing. Pawl  52  is of sufficient stiffness so that ratchet  51  cannot be turned in the non-dispensing direction. Because sufficient force is needed to overcome pawl  52 , inadvertent turning of drive wheel  13 , and thus inadvertent medicament dispensing, is prevented. A secondary advantage of the ratchet-pawl mechanism is the tactile feel the user experiences in turning drive wheel  13 . When turned, every time pawl  52  is over-ridden by one of the ratchet&#39;s teeth, a snap and will be felt through drive wheel  13  to the user&#39;s hand. As yet another advantage, each snap will correspond to a set amount of turn and medicament being dispensed. 
         [0030]    Alternatively, methods for completely locking drive wheel  13  may be used. Such methods may use a resilient, force loaded component, such as a pin to engage a corresponding hole in drive wheel  13 . The user would pull the pin out to enable turning of the wheel. 
         [0031]    In another embodiment, visual, audible or vibratory alarms may be added. Visual alarms could be provided via the indication device. Audible alarms may be provided through a speaker included within the device. A vibratory motor may be used to provide vibratory alarms to the user. The alarms may be used in combination, in escalating frequency, volume or the like or combinations thereof. The circuitry for such alarms and speaker may be incorporated onto the circuit board  24 . 
         [0032]    In yet other embodiments, a transmitter may be provided to transmit data, alarms or both to another device such as phone, computer, server, cloud or the like. Suitable transmitters for incorporation into such a pump are well known. Preferably, the transmitter is a BlueTooth® low energy transmitter. 
         [0033]    It will be apparent that other modifications and variations of the device described are possible within the scope of the described invention. To the extent there are variations of the invention, which are within the spirit of the disclosure or equivalent to the inventions found in the claims, it is the intent these variations are covered as well herein.