Abstract:
A refillable and implantable infusion apparatus and method that includes a needle penetration detector that detects and indications the position of a needle relative to a septum of a drug reservoir of the implantable infusion apparatus. With the needle position data, medical professionals may better ensure they are injecting drugs into the drug reservoir, thus, improving patient safety.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims the benefit of priority to U.S. Provisional Application No. 61/763,277 entitled “Needle Penetration Detection Method and Device for Refillable and Implantable Drug Delivery Systems” filed Feb. 11, 2013, the entire contents of which are hereby incorporated by reference in their entirety for all purposes. 
     
    
     FIELD 
       [0002]    The present invention relates generally to implantable infusion devices for the delivery of medication or other fluids to a patient. 
       BACKGROUND 
       [0003]    Various implantable devices exist for delivering infusate, such as medication, to a patient. One such device is an implantable valve accumulator pump system. This system includes an electronically controlled metering assembly located between a drug reservoir and an outlet catheter. Doctors may refill the drug reservoir on a periodic basis (e.g., once a month) for the patient. 
       SUMMARY 
       [0004]    The systems, methods, and devices of the various embodiments provide an indication to a medical professional when an inserted needle has penetrated a septum of the drug reservoir of an implantable drug delivery device. The various embodiments may enable a medical professional to determine whether to inject drugs into the implantable drug delivery device based on an indication that the inserted needle is in the proper position. In an additional embodiment, the needle penetration detector and its associated devices may give assurances to medical professionals that drugs were delivered to the drug reservoir in the patient properly based on proper needle positioning 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]    The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate example embodiments of the invention, and together with the general description given above and the detailed description given below, serve to explain the features of the invention. 
           [0006]      FIG. 1  is a schematic diagram of an implantable drug delivery system. 
           [0007]      FIG. 2  is a schematic diagram of a needle penetration detector. 
           [0008]      FIG. 3  is a graph of various changes in inductance versus the depth of an approaching needle as observed by a needle penetration detector. 
           [0009]      FIG. 4  is a process flow diagram illustrating an embodiment method for detecting a needle in an implantable drug delivery system. 
       
    
    
     DETAILED DESCRIPTION 
       [0010]    The various embodiments will be described in detail with reference to the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. References made to particular examples and implementations are for illustrative purposes, and are not intended to limit the scope of the invention or the claims. 
         [0011]    The words “exemplary” or “for example” are used herein to mean “serving as an example, instance, or illustration.” Any implementation described herein as “exemplary” or “for example” is not necessarily to be construed as preferred or advantageous over other implementations. 
         [0012]    The systems, methods, and devices of the various embodiments enable delivering metered doses of a drug or other infusate. An embodiment drug delivery system may include a needle penetration detector, an electronics module, and an external programmer to indicate to a medical professional refilling a drug reservoir of the drug delivery system a status of needle insertion into the drug reservoir. In an embodiment, the medical professional may activate the needle penetration detector with the external programmer. The electronics module connected to the needle penetration detector may measure the inductance in a coil surrounding the septum of the drug reservoir prior to insertion of a needle and after insertion of the needle into or near the septum. In an embodiment, a needle penetrating the septum may result in a change in the inductance of the coil compared to the inductance in the coil in normal conditions (i.e., when a needle is not present). In an embodiment, the electronics module may monitor the state of the inductance of the coil and the connected external programmer may indicate the proper or improper position based on the measured inductance of the coil. 
         [0013]    Various embodiments may provide a needle penetration detector that indicates to a medical professional that he has successfully penetrated a needle into the drug reservoir to refill it. Alternatively, the needle penetration detector may indicate to the medical professional that he has not penetrated the needle into the drug reservoir and the medical professional may halt injecting the drug outside of the drug reservoir and re-attempt to penetrate the drug reservoir with the needle. In this way, patient safety is improved and the medical professional may have an instant verification that the needle is in proper position to inject drugs into the reservoir. 
         [0014]      FIG. 1  illustrates an embodiment of an implantable valve accumulator pump system  100  for the delivery of infusate, such as medication. The system  100  may generally include four assemblies. The first major assembly is a rechargeable, constant pressure drug reservoir  10  in series with a bacteria/air filter  24 . In one embodiment, the reservoir  10  comprises a sealed housing  14  containing a bellows  16 . The bellows  16  separates the housing  14  into two parts. Chamber  18  is used to hold the drug or other medicinal fluid. Second zone  20  is normally filled with a two-phase fluid, such as Freon®, that has a significant vapor pressure at body temperature. Thus, as the fluid within the second zone  20  vaporizes, it compresses the bellows  16 , thereby pressurizing the drug in the chamber  18 . The drug can be refilled via a refill septum  12 . The induction coil  42  (shown in  FIG. 2 ) of the needle penetration detector  41  may surround the refill septum  12  and may be electrically controlled by a processor  43  the electronics module  32 . The electronic module  32  may be programmed via an external programmer  34 . 
         [0015]    The two-phase fluid helps maintain the chamber  18  under a constant pressure. When the chamber is refilled, the two-phase fluid is pressurized thereby condensing a portion of the vapor and converting it to liquid. As the chamber  18  is emptied, this liquid vaporizes, thus maintaining the pressure on the bellows  16 . Since the infusate in chamber  18  is under positive pressure, it is urged out of the chamber, through a bacterial filter  24  and toward the metering assembly. 
         [0016]    The second major assembly is an electronically controlled metering assembly comprising two normally closed solenoid valves  26 ,  28 , which are positioned on the inlet and outlet sides of a fixed volume accumulator  30 . The valves are controlled electronically via an electronics module  32 , which may be programmed utilizing the external programmer  34 . The metering assembly is designed such that the inlet valve  26  and the outlet valve  28  are never simultaneously open. 
         [0017]    The third major assembly is an outlet catheter  36  for medication infusion in a localized area. The delivery of fluid occurs at an infusion site that is below the accumulator pressure, thereby forcing discharge through the catheter  36 . 
         [0018]    The drug reservoir, electronically controlled metering assembly, and needle penetration detector may be contained within a biocompatible housing, also containing a power source (e.g., battery), that may be implanted within the body of a human or animal patient. The outlet catheter may be integral with the housing, or may be a separate component that is attached to the housing. An access port  31 , in communication with the catheter  36 , may be provided downstream of the metering assembly. The access port  31  may be used, for example, to manually provide a bolus dose of medication to the patient. 
         [0019]    The fourth assembly of the system of  FIG. 1  is the external programmer  34  used to communicate and program the desired medication regimen and to activate and/or control the needle penetration detector  41 . In an embodiment, the external programmer  34  may be a handheld unit with a touch screen. The external programmer  34  may provide a wireless data transfer link to a wireless communication transceiver within the implanted electronics module  32  and may be enabled to exchange information with the electronic module  32 , including but not limited to battery status, diagnostic information, calibration information, etc. In an embodiment, the external programmer  34  may send an activation instruction to the electronics module  32  to activate the electronics module  32 . In an embodiment, the external programmer  34  may indicate to a medical professional the position of an inserted needle by receiving an indication instruction from the electronics module  32  which may indicate the needle&#39;s location relative to the refill septum  12 . In an embodiment, the electronics module  32  may include a coil configured to send and receive electromagnetic signals to/from the external programmer  34 . 
         [0020]      FIG. 2  illustrates an implantable drug delivery device  200  that includes an embodiment needle penetration detector  41 . In an embodiment, the refill septum  12  may be surrounded by an induction coil  42  of the needle penetration detector  41 . A medical professional may pierce a needle  40  through the refill septum  12  surrounded by the induction coil  42 . The electronics module  32  may include a controller  92 . In an embodiment, the controller  92  may include a processer  43  coupled to a memory  44 . The processor  43  may be any type of programmable processor, such as a microprocessor or microcontroller, which may be configured with processor-executable instructions to perform the operations of the embodiments described herein. Processor-executable software instructions may be stored in the memory  44  before they are accessed and loaded into the processor  43 . The processor  43  may include internal memory sufficient to store the application software. The memory  44  may be volatile, nonvolatile such as flash memory, or a mixture of both. The electronics module  32  may include an alternating current (AC) power source  50 . The AC power source  50  may be coupled to a wireless communication coil  93  of the electronics module  32  via a switch  91  coupled to the controller  92 . The controller  92 , particularly the processor  43 , may control the operation of the switch  91  to induce a modulated magnetic field on coil  93  to communicate information to and receive commands and configuration data from a programmer  34  via a wireless communication link  97 . The use of modulated magnetic fields to induce currents in induction coils to communicate with implanted medical devices is well known. For example, currents flowing through the wireless communication coil  93  may be modulated by the controller or a dedicated wireless communication transceiver to induce currents in a wireless communication coil  94  in an external programmer  34  to communicate information to the external programmer  34 , and vice versa. The controller  92  may be coupled to the wireless communication coil  93  and may monitor the current, voltage, and/or inductance of the coil  93  and function as a wireless communication transceiver to receive information via the wireless communication coil  93  from an external programmer  34 . As an example, the controller  92  may receive operational configuration information such as a dosage regimen via the wireless communication coil  93  from the external programmer  34 . 
         [0021]    In an embodiment, the controller  92  may be coupled to an inductance monitoring circuit  45  of the needle penetration detector  41 . The inductance monitoring circuit  45  may measure the inductance of the induction coil  42  and provide indications of the measurements of the inductance to controller  92 . The AC power source  50  may be coupled to the induction coil  42  via a switch  90  coupled to the controller  92 . The controller  92  may control the operation of the switch  90  to induce a magnetic field on coil  12 . 
         [0022]    In an embodiment, the inductance monitoring circuit  45  may measure the inductance of the induction coil  42  resulting from the change in inductance from an approaching needle and provide the measurement of the inductance to the controller  92 . The controller  92  may compare the change in inductance from the approaching needle to an established baseline inductance. The controller  92  may determine the needle&#39;s position and communicate that determination to the external programmer  34 , which may subsequently indicate the position of the needle  40 . In another embodiment, the controller  92  may generate indications of the measurements of the inductance received from the inductance monitoring circuit  45  and communicate the indications of the measurements to the external programmer  34 . 
         [0023]    In an embodiment, the external programmer  34  may include a processor  47  coupled to a memory  46  and to an indicator  48 . Software instructions may be stored in the memory  46  before they are accessed and loaded into the processor  47 . The external programmer  34  may include an AC power source  95  coupled to a wireless communication coil  94  via a switch  96  coupled to the processor  47 . The processor  47  may control the operation of switch  96  to induce a magnetic field on the wireless communication coil  94  to receive and communicate information. For example, the wireless communication coil  94  may be controlled to communicate information from the electronics module  32 . The processor  47  may be coupled to the wireless communication coil  94  and may monitor the current, voltage, and/or inductance of the coil  94  to receive information from the via the wireless communication coil  94 . As an example, the processor  47  may receive information via the wireless communication coil  94  from the electronics module  32  of the implantable drug delivery device  200  regarding whether a needle has been detected within the induction coil  42 . The processor  47  may be connected to an indicator  48  to indicate the position of a needle based on received indication instructions from the electronics module  32 . For example, the indicator may be a display, a speaker for an audio sound or message, or a vibrator to generate haptic feedback. 
         [0024]    In an embodiment, the external programmer  34  may receive, via the wireless communication link  97  described above, information regarding the position of the needle  40  and/or indications of the measurements of the inductance of the induction coil  42  from the implantable drug delivery device  200 . The information communicated from the implantable drug delivery device  200  may be a direct measure of inductance of the induction coil  42  or data that the external programmer processor  47  can used to determine changes in inductance. For example, the processor  47  may compare the change in inductance from the approaching needle  40  to a baseline inductance established before the needle  40  was inserted into the patient to detect when the needle  40  is in a proper or improper position. Alternatively, the processor  43  of the implantable drug delivery device  200  may compare measurements of the inductance of the induction coil  42  and transmit to the external programmer  34  an indication of whether the needle  40  is in a proper or improper position. If the needle  40  is in an improper position, the external programmer  34  may inform the medical professional via the indicator  48 , thereby allowing the medical professional to reposition the needle into the refill septum  12  of the drug reservoir. 
         [0025]      FIG. 3  illustrates a curve of the measured inductance (L) over the depth of a needle (y) observed by a needle penetration detector interacting with an approaching needle. In an embodiment, the inductance monitor  45  may measure the inductance of coil  42  of a needle penetration detector prior to inserting a needle into a patient to establish a baseline inductance measurement. The graph of inductance (L) over the depth of a needle (y) illustrated in  FIG. 3  illustrates the relative change in inductance (L) from the baseline inductance established before the insertion of as needle into a patient and the change in inductance (L) which may indicate the position of a needle. When AC power is applied to the induction coil of the needle penetration detector the inductance (L) but the needle is not inserted in the induction coil, the inductance in the induction coil may be measured as a baseline inductance indicated by inductance measurement region  51 . When a needle is inserted into the patient a first far distance away from the induction coil of the needle penetration detector and the AC power is applied to the induction coil of the needle penetration detector, the inductance in the induction coil may exceed the baseline inductance by a relatively small value as indicated by inductance measurement region  58 . When a needle is inserted to a second distance closer to the induction coil of the needle penetration detector (e.g., inserted deeper into the patient toward the coil) and the AC power is applied to the induction coil of the needle penetration detector the inductance in the induction coil may exceed the baseline inductance by a larger value as indicated by inductance measurement region  56 . When the needle is inserted in the refill septum (i.e., into the induction coil of the needle penetration detector surrounding the refill septum) and the AC power is applied to the induction coil of the needle penetration detector the inductance in the induction coil may be a high inductance value as indicated by inductance measurement region  58 . In an embodiment, a high inductance value exceeding a threshold inductance  52  may indicate that the needle is positioned in the septum. 
         [0026]      FIG. 4  illustrates an embodiment method  400  for detecting a position of a needle in a refill septum of an implantable drug delivery device. The electronics module  32  determines the position of a penetrating needle relative to the refill septum  12  of the drug reservoir. In block  402  an electronics module  32  of the implantable drug delivery device may activate the needle penetration detector  41 . In an embodiment, an electronics module  32  may receive an activation instruction to activate a needle penetration detector  41  from an external programmer  34 . For example, a medical professional may use the external programmer  34  to send the activation instructions to the electronics module  32  within the implantable drug delivery device implanted within the patient. In an embodiment, the processor  43  of the electronics module  32  within the implantable drug delivery device may periodically activate the needle penetration detector by sending electricity to the induction coil  42 . For example, the electronics module  32  may turn on the needle penetration detector every second, quarter second, one-hundredth of a second, microsecond, five microseconds, millisecond, etc. 
         [0027]    In block  404  the induction monitor  45  of the electronics module may collect a baseline measurement from the needle penetration detector  41 . For example, the electronics module  32  may collect a baseline measurement of the inductance of the induction coil  42  before a needle is inserted into the refill septum. In block  406  the electronics module  32  may indicate the baseline measurement to the external programmer  34 . For example, the electronics module  32  may transmit the baseline measurement to the external programmer  34  via the coils  93 ,  94 . 
         [0028]    In block  408  the induction monitor  45  of the electronics module  32  may collect a new measurement from the needle penetration detector  41 . The new measurement may be collected after the medical professional inserts a needle into the patient. In block  410 , the electronics module  32  may communicate the new inductance measurement to the external programmer  34 . In block  412 , a processor of the external programmer  34  may compare the baseline and new measurements to determine the difference between measurements. The comparison may result in a high state  54 , an intermediate state  56 , or a low state  58  as shown in  FIG. 3 . For example, the processor  47  of the external programmer  34  may compare the difference in inductance between the baseline measurement and the new measurement to one or more threshold values, such as threshold values associated with a high state  54  that indicates when the needle has penetrated the induction coil  42  of the refill septum. 
         [0029]    In determination block  414 , a processor  47  of the external programmer  34  may determine whether the difference in measurements is below a threshold  52 . In response to determining that the difference in measurements is below the threshold  52  (i.e., determination block  414 =“Yes”), the processor  47  of the external programmer  34  may indicate via an indicator  48  or display that the needle did not penetrate the refill septum in block  416 . For example, a medical professional may have inserted the needle  40  outside of the refill septum  12  in which case the indicator  48  of the external programmer may display an appropriate warning or message, such as “FAIL.” Based on the indication, the medical professional may re-insert or move the needle and the electronics module and the external programmer may repeat blocks  408 ,  410 ,  412 . In an embodiment, the processor  47  of the external programmer  34  may provide an intermediate indication via the indicator  48  when the measured inductance indicates that the needle is close but not yet within the refill septum. This intermediate indication may aid a medical professional in aligning the needle with the refill septum before penetrating the skin of the patient. 
         [0030]    In response to determining that the difference in measurements is equal to or greater than the threshold  52  (i.e., determination block  414 =“No”), the processor  47  of the external programmer  34  may indicate the needle did penetrate the septum in block  418 . For example, a medical professional may have inserted the needle  40  directly in the center of the refill septum  12 , in which case the indicator  48  of the external programmer may display an appropriate message, such as “SUCCESS.” 
         [0031]    In alternative embodiment, the processor  43  within the implantable drug delivery device may be configured with processor-executable instructions to perform the operations of blocks  412  and  414  and communicate an indication of success or failure (and optionally an intermediate indication) to the external programmer  34 . In this embodiment, the processor  47  of the external programmer  34  may receive the indication from the implantable drug delivery device and use the received indication to generate a corresponding warning or message on the indicator  48  or display. 
         [0032]    In block  420 , the electronics module  32  of the implantable drug delivery device may deactivate the needle penetration detector based on a received deactivation instruction from the external programmer  34 . For example, a medical professional may press a button labeled “Deactivate” on the external programmer  34 , which prompts the external programmer to send a deactivate instruction via coil  94  to coil  93  of the electronics module  32  of the implantable drug delivery device. Upon receiving the deactivation instructions, the electronics module of the implantable drug delivery device may cut off electricity to the induction coil  42  of the needle penetration detector  41 , thereby conserving the battery life of the electronics module  32 . 
         [0033]    The foregoing method descriptions and the process flow diagrams are provided merely as illustrative examples and are not intended to require or imply that the blocks of the various aspects must be performed in the order presented. As will be appreciated by one of skill in the art the order of blocks in the foregoing aspects may be performed in any order. Words such as “thereafter,” “then,” “next,” etc. are not intended to limit the order of the blocks; these words are simply used to guide the reader through the description of the methods. Further, any reference to claim elements in the singular, for example, using the articles “a,” “an” or “the” is not to be construed as limiting the element to the singular. 
         [0034]    The various illustrative logical blocks, modules, circuits, and algorithm blocks described in connection with the aspects disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and blocks have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention. 
         [0035]    The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.