Abstract:
A disposable device is provided which accurately and reliably delivers an infusable liquid to a patient. The infusion device includes a housing which defines a bladder chamber. A compressible bladder is disposed in the bladder chamber and is compressed by the housing upon filling the bladder with an infusable liquid to create a pressurized bladder. The infusion devices further includes a delivery system for subcutaneously delivering the infusable liquid to a body. The delivery system includes a collapsible member that supports an injection needle and a cannula. The injection needle is used to insert the cannula into the skin of the body being treated. The cannula is in communication with the bladder during delivery of the infusable liquid. The housing includes microfluidic passageways that allow communication between fluid in the bladder and the cannula.

Description:
BACKGROUND OF THE INVENTION 
     Today, there are numerous medical ailments and diseases which can be treated by medicines, such as drugs, hormones, etc. One such disease is diabetes mellitus which can be characterized by the absence of or inappropriate utilization of insulin secreted by the pancreas. Insulin acts to facilitate the delivery of glucose into the cells where it undergoes various biochemical reactions. The result of diabetes is high levels of glucose in the blood and low levels of cellular glucose which can be fatal. 
     Generally, there are two forms of diabetes. Type I diabetes usually emerges before the age of 30 and is characterized by a reduction in the amount of insulin secreted by the pancreas. Type II diabetes is far more common and usually starts after age 30 and is characterized by normal insulin secretion but the biochemical composition of the insulin does not facilitate the glucose transport effectively. 
     To ameliorate this problem, conventional treatment has included one to several subcutaneous injections of insulin per day. More recently, insulin is delivered to the patient on a continuous basal basis as well as a bolus basis by a portable infusion pump, such as disclosed in U.S. Pat. No. 4,498,843 to Schneider et al These pumps typically include a syringe or cartridge filled with insulin, an electromechanical mechanism that advances the syringe or cartridge plunger, and a controller that controls the proper dosage. Catheter tubing delivers the insulin from the syringe to an infusion tubing and needle set which is inserted under the skin of the patient. 
     SUMMARY OF THE INVENTION 
     Prior art systems for delivering an infusable liquid to a body have suffered from at least two deficiencies. First, these portable systems are very expensive. For example, the initial cost alone for the system and accessories can be between 4,000 and 6,000 dollars. Recurring costs of the system and dressings can average between 200 and 300 dollars per month. Second, the catheter tubing of these systems requires a substantial amount of insulin for priming purposes which can induce inaccuracies in the delivery dosage. Further, the tubing may easily kink resulting in a loss of delivery, or insufficient dosing of, the infusable to the patient. 
     Accordingly, there is a need for an inexpensive and hence disposable infusion device which accurately, consistently, and reliably delivers infusable liquids, such as insulin, to a patient. In accordance with the present invention, a disposable infusion device includes a housing which defines a bladder chamber. A compressible bladder is disposed in the bladder chamber and is compressed by the housing upon filling the bladder with an infusable liquid to create a pressurized bladder. The infusion device further includes a delivery system for subcutaneously delivering the infusable liquid to the body of the user. 
     In accordance with one aspect of the present invention, the delivery system includes a collapsible member that supports an injection needle and a cannula. The injection needle is used to insert the cannula into the skin of the body being treated. The cannula is in communication with the bladder during delivery of the infusable liquid. In one embodiment, the housing includes microfluidic passageways that allow communication between fluid in the bladder and the cannula. 
     The housing includes a first side and a second side with an adhesive or adherent on the first side for attaching the infusion device to the skin of the body for a period of time, such as 3-5 days. Preferably, the adhesive forms a seal around the cannula to create a sanitary injection site into the body. 
     In accordance with other aspects of the present invention, the infusion device includes an alarm or radio frequency signal to warn the user when the bladder is substantially or nearly empty. This alarm can include an audible or vibrational alarm. The infusion device can also include an occlusion alarm to warn the user when a predetermined amount of infusable liquid fails to be delivered to the body. 
     In accordance with yet other aspects of the present invention, the infusion device includes a controller, such as a microcontroller, for controlling operation of the infusion device. For example, the controller can assess, diagnose, or transmit information about and operation of the infusion device. A power source or battery is used to power the controller. The controller is programmable, in one embodiment, for injecting predetermined amounts of infusable liquid, preferably selected by a user input, into the body. 
     A remote control device can be used to program and control operation of the infusion device. A signaling mechanism, such as an LED, can be included on the infusion device to confirm programming by the remote control device. The remote control device can include a memory storage device to store the programmed instructions sent to the infusion device, and to provide history information on the performance/operations of the device. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. 
     FIG. 1 is a plan view of a disposable infusion device in accordance with an embodiment of the present invention. 
     FIG. 2 is a top cut-away view of the infusion of device of FIG. 1 taken along different thickness levels to illustrate microfluidic passageways in the housing of the infusion device. 
     FIG. 3 is a cross-sectional view taken along line  3 — 3  of FIG.  2 . 
     FIG. 4 is a side view of the infusion device taken along line  4 / 5 — 4 / 5  of FIG. 1 illustrating the injection needle and cannula in a pre-injection position prior to being inserted into the body being treated. 
     FIG. 5 is a side view of the infusion device taken along line  4 / 5 — 4 / 5  of FIG. 1 illustrating the injection needle in an injection position for inserting the cannula into the body being treated. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A description of preferred embodiments of the invention follows. FIG. 1 illustrates a limited-life, disposable infusion device or pump, generally designated as reference numeral  10 . The infusion device  10  is used to deliver predetermined amounts of infusable liquid, such as liquid medicines, insulin, etc., to an injection site on the patient or user in a controlled and reliable manner. It is important that the device  10  deliver controlled amounts of infusable liquid so as to not deliver more infusable liquid than required, would could be fatal. 
     The infusion device  10  includes a housing  12  which is preferably constructed of a strong, heat-stable material, such as polycarbonate or a high impact styrene. The housing  12 , in one embodiment, can be flexible to conform to the body to which it is attached. The housing  12  defines a bladder chamber  14  in which a bladder  16  is situated. In one embodiment, the bladder  16  is filled with insulin prior to use via an injection port  18  with a syringe. As the bladder  16  is filled, the housing  12  including a member comprising, for example, an integral cantilevered arm  20 , compress the bladder to create a biasing force pressurizing the bladder for expelling the infusable therein when the pressure is relieved by actuating buttons  26  as will be described later. In alternative embodiments, arm  20  can be formed from a different material than the housing  12  and attached thereto. 
     The bladder  16  can formed from sheets of a durable material such as silicon, polypropylene, or vinyl sealed together to form a fluid tight compartment. In one embodiment, the bladder  16  holds up to  300  units of U- 100 , U- 50 , or U- 40  insulin. Typically, the average diabetic uses about  40  units per day, not including initial priming. The infusion device  10  is capable of delivering various types of insulin, for example, ultra-fast, rapid, intermediate, and long-lasting insulin. In alternative embodiments, more than one bladder can be included in the housing  12  for delivering different types of insulin with the same infusion device  10 . 
     Prior art devices have employed mechanisms such as stepper motors and peristaltic pumps to force the insulin from a reservoir into the user. These devices typically require heavy, powerful batteries which are carried by the user. In contrast, in one embodiment of the present invention, the housing itself provides the force for delivering the insulin to the user. This avoids heavy and costly stepper motors and the like. 
     Preferably, the infusion device  10  is relatively small and flexible, such as the size of a credit card. The device  10  preferably includes an adhesive  13  on the backside thereof (see FIGS.  4  and  5 ), such that the device can be adhered to the skin of the user for a predetermined amount of time, such as 3-5 days. Preferably, the adhesive  13  forms a seal around the injection site  15  for sanitary purposes. Thus, the device  10  can be worn at virtually all times, such as during water activities (swimming/showering) and even while sleeping. 
     As illustrated in a top cut-away view of the inside of device  10  in FIG. 2, a plurality of microfluidic passageways or channels  22  provide fluid communication between the bladder  16  and the cannula  28 . In one embodiment, the channels  22  vary in both length and width, as illustrated in the view of the channels in FIGS. 2 and 3. The channels  22  can be formed by laminating different layers  24  of bladder material with each layer having a channel formed therein. The channels  22  can be formed by such methods as laser etching and die-cutting. The channels  22  facilitate accurate and varying dosage levels to the user. For example, the six channels can correspond to six basal dosages. These basal rates can correspond to a range of about 0.0 to 35.0 units/hour wherein the insulin is delivered in 0.1 unit increments. In alternative embodiments, conventional tubing, such as miniature spaghetti tubing, can be used to provide fluid communication between the bladder  16  and the cannula  28 . 
     A plurality of buttons  26  actuate stop cocks (not shown) and function as switches which can be actuated by the user to control which of the channels  22  is selected and placed in fluid communication with the cannula  28 . Alternatively, micro-electro-mechanical systems or MEMS can be used to control the channels  22  in accordance with the present invention. 
     The buttons/switches  26  correspond, in one embodiment, to six different basal dosages. It is understood that more basal dosages can be easily incorporated into the preferred embodiment of the invention. Furthermore, an additional button can be provided to correspond to a bolus dosage which is an additional dose of insulin. Typically, this bolus dosage is administered at or before mealtime, when glucose levels will increase with the ingestion of food. The buttons  26  can have embossed numbering thereon to aid the visually impaired. Alternatively, or in addition to, the buttons  26  can provide feedback to the operator, such as tactile or sound feedback, to confirm activation of the buttons. 
     As is well known in the art, the cannula  28  may be subcutaneously inserted by an injection needle or introducer needle  30 . In one embodiment, the injection needle  30  is a  26  gauge needle potted in a retaining member  32 . The cannula  28  is preferably made of a soft and flexible material, such as polytetrafluorethylene (PFTE). The housing  12  can be substantially transparent such that the user can visually inspect the bladder  16 , the channels  22 , and the injection site  15 . 
     As shown in FIG. 4, the injection needle  30  and cannula  28  are supported and protected by a collapsible member  46  prior to injection. To insert the cannula  28  below the skin of the user, the retaining member  32  and needle  30  are extended toward the body being injected. FIG. 5 illustrates the introducer needle  30  in the extended position outside the housing  12  inserting the cannula  28  to a sufficient depth below the skin of the user. Because the infusion device  10  attaches directly to the skin of the user, the cannula  28  is relatively short such that kinking is avoided. Furthermore, the collapsible member  46  provides a stable base such that the cannula  28  is not easily moved around under the skin of the body. The retaining member  32  and needle  30  are withdrawn leaving the cannula  28  in place. 
     A firing mechanism can be used to inject the needle  30  and cannula  28  into the body. For example, a spring-loaded injector device can be used, such as disclosed in U.S. Pat. No. 5,851,197, issued on Dec. 22, 1998 to Marano et al., the contents of which are incorporated herein by reference in its entirety. In alternative embodiments, the retaining member  32  can be manually pushed into the skin by the user. 
     The infusion device  10  can also include an electro/mechanical start button  34  for initiating the insulin delivery process. A controller  36 , powered by a power source or battery  38 , functions to control operation of the device  10 . In a preferred embodiment, the controller  36  is a programmable microcontroller to control functionality of the device such as varying the basal dosage(s). Preferably, the power source is permanently attached to the housing  12 . 
     In one embodiment, a remote control device  42  can be used to control operation of the device  10 . Preferably, the device  42  includes a controller  43 , such as a microcontroller, to control operation of the infusion device  10 . The device  42  can employ any wireless connectivity standards, such as RF, IR, and BLUETOOTH standards, the latter being a trademark of Telefonaktiebolaget LM Ericsson, a Sweden corporation. The remote control device  42  can include functional buttons, such as a start button or bolus button to reduce accidental actuation of the same. Additionally, the device  42  can be used to program the controller  36  to vary the basal rates, for example. 
     The remote control device  42  in one embodiment includes a memory storage device  44  to store the programmed instructions sent to the device  10 . These instructions can be later uploaded to a computer for tracking. Additionally, the memory storage device  44  can receive other information from the infusion device  10 , such as how much insulin has been delivered to the body, i.e., the history of the infusion treatment. A signaling device, such as an audible or visual indicator (LED or LCD) can be incorporated onto the device  10  to confirm receipt of the instructions. Another signaling device can be incorporated onto the remote control device  42  which alerts the user when the device  42  is out of programming range, i.e., when the device  42  is too far from the infusion device  10  to program the same. This type of an alarm can be referred to as a proximity alarm. In a preferred embodiment, the remote control device  42  is small enough so as to be operable by one hand. 
     Preferably, the device  10  includes an alarm  40  which can be, for example, an audible alarm or a vibrational alarm. In one embodiment, the alarm  40  signals to the user when the bladder  16  is substantially or nearly empty. In another embodiment, the alarm  40  can signal when a predetermined number of insulin units (e.g., 2-4 units) are missed. This type of an alarm can be referred to as an occlusion alarm. 
     The housing  12  can include a unidirectional breathable material, such as Tyvek® material, disposed on the side of the housing which contacts the skin of the user. Tyvek® is a registered trademark of E.I. Du Pont de Nemours and Company. A light coating of adhesive  13  is applied over the breathable material. This allows the user&#39;s skin to breathe allowing the device  10  to remain comfortably on the user for an extended period of time. Preferably, the device  10  is waterproof such that it can be worn continuously, even in the shower. 
     The operation of the device will now be described. The device is provided in a sterile package and is removed therefrom for use. The bladder  16  is filled by a syringe by the user via injection port  18 . The device  10  is pre-primed by the user to fill the cannula  28  with insulin. The user then removes a release liner (not shown) from the adhesive side of the infusion device  10 . The device  10  is then adhered to the user, for example, at a sanitarily cleaned area of the abdomen. The cannula  28  is inserted into the skin via injection needle  30  by pressing insertion button  32 . The user activates the device by pressing the start button  34  and chooses the desired dosage level by pressing a button  26 . Preferably, the device  10  is discarded after a predetermined amount of time, for example, 3-4 days. Another disposable device  10  can be attached to the skin to continue the delivery process, preferably at another injection location. 
     While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims.