Apparatus and method for detecting an empty reservoir in an infusion pump

Abstract

The empty reservoir state is detected using pump measurement data corresponding to the suction operation of the infusion pump. [Solution] The apparatus and method detect an empty reservoir state in an infusion pump using pump measurements, such as motor current during suction. The infusion pump acquires and analyzes pump measurements indicating pressure during suction and determines whether the pump measurements meet criteria corresponding to an empty reservoir state, such as a pressure threshold corresponding to a pump measurement that would be exceeded when the reservoir is empty, a range of pump measurements indicating a pressure exceeding the normal operating pressure of the pump, and a designated signal waveform corresponding to a pump measurement indicating a pressure exceeding the normal operating pressure of the pump. The apparatus and method can be configured to ignore one or more pump measurements obtained in one or more parts of the duration of the suction operation, which are characterized by transient increases resulting from the normal operation of the pump mechanism.

Description

Technical Field

[0001] Exemplary embodiments generally relate to a technique for detecting an empty reservoir state using pump measurement data corresponding to the suction operation of an infusion pump.

Background Art

[0002] Infusion pumps generally employ a reservoir having a known quantity of liquid and a known discharge stroke volume, and count down the dosing to estimate how much liquid remains in the reservoir. If the amount of liquid in the reservoir is not known precisely, the infusion pump may fail to deliver some of the dosing at the end of its life (e.g., the end of the count down), such as when the dosing stroke volume exceeds the nominal amount.

[0003] One solution for monitoring the filling level or empty state of the reservoir of an infusion pump is to use a dedicated sensor. However, adding a sensor to an infusion pump increases the complexity of the system (e.g., increases mechanical, electrical, and / or software complexity), increases the power consumption of the system, and increases the cost of the infusion pump.

[0004] For medical devices where some or all of the components, such as wearable drug delivery pumps, are disposable for ease of use and cost effectiveness, it is not desirable to add another component such as a reservoir status sensor and increase the associated costs and complexity. Therefore, there is a need to accurately detect that the reservoir of an infusion pump is in an empty state without adding components and thereby increasing the complexity and cost of the infusion pump.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

[0006] By exemplary embodiments, the above-mentioned and other problems are overcome, and additional advantages are realized.

[0007] According to an exemplary embodiment, an infusion device is provided, comprising: a liquid chamber; a pump including a pump mechanism configured to control the suction of liquid from a reservoir to the chamber during an aspiration operation and the discharge of the liquid from the chamber during a discharge operation; and a processing device for analyzing one or more pump measurements obtained during the aspiration operation and determining when the one or more pump measurements meet a specified criterion related to the empty reservoir state of the reservoir.

[0008] According to an exemplary embodiment, the pump measurement value is a measurement value of the motor current of the pump.

[0009] According to an exemplary embodiment, the processing device is configured to terminate the operation of the pump mechanism when one or more pump measurements meet the specified criteria.

[0010] According to an exemplary embodiment, the processing device analyzes additional pump measurements if one or more pump measurements meet the specified criteria, and determines when the additional pump measurements will meet the specified criteria before the termination operation of the pump mechanism. For example, the processing device can be configured to terminate the operation of the pump mechanism if the additional pump measurements meet the specified criteria.

[0011] According to an exemplary embodiment, the designated criterion is one or more criteria selected from a pressure threshold corresponding to a pump measurement value that is exceeded when the reservoir is empty, a range of pump measurement values ​​that indicate a pressure exceeding the normal operating pressure of the pump, and a designated signal waveform corresponding to a pump measurement value that indicates a pressure exceeding the normal operating pressure of the pump.

[0012] According to an exemplary embodiment, the processing device is configured to analyze one or more pump measurements obtained during a selected portion of the duration of the suction operation.

[0013] According to an exemplary embodiment, the processing device is configured to ignore one or more pump measurements obtained during one or more parts of the duration of the suction operation, which are characterized by transient increases resulting from the normal operation of the pump mechanism.

[0014] According to an exemplary embodiment, the pump measurement is selected from one or more pump motor currents, pump motor voltages, pump encoder counts, pump motor drive counts, and pump motor drive times.

[0015] Additional embodiments, and / or other embodiments, as well as the advantages of the exemplary embodiments, are described in the following description, or are evident from the following description, or can be learned through practice of the exemplary embodiments. Exemplary embodiments may include an apparatus having one or more of the above embodiments, and / or one or more of the above features and / or combinations thereof, and a method for operating such an apparatus. Exemplary embodiments may include one or more of the above features and / or combinations thereof, for example, as described in the appended claims. [Brief explanation of the drawing]

[0016] The above and / or other aspects and advantages of the exemplary embodiments will be more readily apparent from the following detailed description, along with the accompanying drawings.

[0017] [Figure 1] This is a partial perspective view showing an example of a pump component of an exemplary drug delivery device operating according to an occlusion detection algorithm in an exemplary embodiment of the present invention. [Figure 2]A partial perspective view showing an example of a pump component of an exemplary drug delivery device operating according to an occlusion detection algorithm in an exemplary embodiment of the present invention. [Figure 3A] A perspective view showing the arrangement of the pump components shown in FIGS. 1 and 2 of an exemplary drug delivery device in a state where the discharge stage is ready to operate. [Figure 3B] A perspective view showing the arrangement of the pump components shown in FIGS. 1 and 2 of an exemplary drug delivery device in a state where the suction stage is ready to operate. [Figure 3C] A perspective view showing components in an exemplary drug delivery device including the examples of the pump components shown in FIGS. 1 and 2, and related electronic circuits on a printed circuit board. [Figure 4A] A block diagram showing components of an exemplary drug delivery device. [Figure 4B] A circuit diagram of a drug delivery device pump motor having a current sensor in an exemplary embodiment of the present invention. [Figure 5] A diagram showing pump measurement data from an exemplary delivery device showing motor current during the discharge period and changes at different voltages. [Figure 6A] A diagram showing raw pump measurement data (e.g., motor current) from an exemplary delivery device during the suction and discharge strokes. [Figure 6B] A diagram showing filtered pump measurement data (e.g., motor current) from an exemplary delivery device during the suction and discharge strokes. [Figure 7A] A diagram showing the change in pump motor current during suction after the pump reservoir has emptied. [Figure 7B] A diagram showing the change in pump motor current during suction after the pump reservoir has emptied. [Figure 8] Pump measurement data from an exemplary delivery device, showing motor current versus the suction stroke and the empty reservoir point. [Figure 9]A flowchart showing an example of the operation of an exemplary drug delivery device that executes an empty reservoir detection algorithm in an exemplary embodiment of the present invention.

[0018] Throughout the drawings, like reference numerals are understood to refer to like elements, features, and structures.

Best Mode for Carrying Out the Invention

[0019] Next, exemplary embodiments of the present disclosure shown in the accompanying drawings will be described in detail. The exemplary embodiments described herein illustrate the invention and the present disclosure with reference to the drawings, but are not limited thereto.

[0020] Occlusions in an infusion pump can be caused by restrictions in flow or stenosis of a passage, such as a pinched catheter or tissue occlusion in a liquid delivery device such as a drug dosing pump, or by an empty drug reservoir. It is important to measure and detect early changes in pump pressure due to pump conditions such as occlusion or empty reservoir, and to reduce inaccuracies in liquid delivery that can lead to failed dosing.

[0021] Some infusion pumps rely on a countdown of the dosage to determine when their reservoir is empty. These pumps operate based on a known reservoir capacity and known stroke volume, counting doses until the reservoir or fluid chamber is theoretically empty. This countdown method can lead to failed doses when the reservoir is nearing the end of its life if the stroke volume exceeds the nominal value. Some such infusion pumps require over-pumping of empty reservoirs to ensure that all medication is administered in the worst-case scenario. Over-pumping has the disadvantage of prolonging delivery time without benefiting the patient. In addition, significant power is used because the suction stroke requires excessive power when the reservoir is empty compared to the power used for suction strokes when the reservoir is not empty. Another method of detecting an empty reservoir condition involves the use of an empty reservoir sensor, but this undesirably increases the complexity, cost, and expected power consumption of the infusion pump.

[0022] Exemplary embodiments for detecting an empty reservoir state, as described herein, provide a technical solution to the technical problems described above. According to an advantageous aspect of the exemplary embodiments of this disclosure, a pump and a method for operating the pump are provided, employing an empty reservoir algorithm for detecting an empty reservoir state using measured pump parameters, and software for controlling the operation of a pump control device or processor based on the measured pump parameters.

[0023] The measured pump parameters may include, but are not limited to, pressure, motor current, motor voltage, encoder count, motor drive count, delivery pulse energy, and motor drive time. For example, since motor current can indirectly correlate with pump pressure, current sensing is considered a reliable method for detecting blockages in the flow path of a liquid delivery device, such as those caused by an empty reservoir. When the reservoir becomes empty, the liquid flow rate in the pump decreases, resulting in an increase in back pressure. This increase in back pressure acting on the piston surface of the pump causes, for example, an increase in the torque demand required by the pump and motor to overcome this pressure. This increase in torque demand corresponds to an increase in the current drawn into the pump motor, which is one way to detect a downstream blockage.

[0024] High positive downstream pressure can be detected based on current demand, but high upstream pressure is not easily detected because it theoretically assists the pump and slightly reduces current demand. However, in some positive displacement pumps, the pump first draws in a certain amount of fluid and then discharges it. While it can be very difficult to detect positive upstream pressure associated with fluid suction due to the decrease in current demand, it is possible to detect low pressure or events that obstruct upstream flow (e.g., an empty reservoir) because the current increases during the suction stroke.

[0025] According to an advantageous aspect of an exemplary embodiment of the present disclosure, the empty reservoir algorithm provides reliable and timely detection of an empty reservoir condition to mitigate failed or inaccurate dosing. The empty reservoir algorithm controls the liquid delivery device to obtain measured values ​​of device parameters indicating the liquid pressure during a period of inhalation or aspiration (e.g., a suction stroke), and a specified criterion that is a threshold value (T) of the motor current. EMPTYThe pump mechanism in a liquid delivery device is controlled to stop pump operation when the measured values ​​meet criteria corresponding to an empty reservoir state, such as an empty reservoir, or other criteria such as the expected shape of the current motor data during the suction period. For example, it is possible to detect an empty state by monitoring pump parameters (e.g., motor current) measured in a critical portion of the suction stroke, as described below. According to the technical principles underlying the technical solutions described herein, pulling an empty reservoir requires an increase in torque during the suction portion of the pumping cycle. This increased torque demand increases the current in a characteristic shape during a specific period of the suction stroke. It is possible to specify criteria for detecting the characteristic shape of the suction current when the pump is empty in the pump measurements.

[0026] In exemplary embodiments of this disclosure, motor current is the parameter measured as an indicator of pressure. It should be understood that, without limitation, other parameters may also be measured, including but are not limited to, motor voltage, motor drive time, motor coasting time, delivery pulse energy, motor drive count, motor coasting count, and delta encoder count.

[0027] The empty reservoir algorithm of the exemplary embodiment is particularly useful for volumetric pumps. A volumetric pump is understood to be a type of pump that operates on the principle of filling a chamber (e.g., with liquid drug from a reservoir) in one stage and emptying the liquid from the chamber (e.g., to a delivery device such as a cannula placed in the patient) in another stage. For example, a reciprocating plunger pump or a rotary metering pump can be used. In either case, a piston or plunger is retracted from the chamber, drawing or drawing drug into the chamber and filling the chamber with a certain amount of drug (e.g., from a drug reservoir or cartridge to an inlet port). Then, the piston or plunger is reinserted into the chamber, and a certain amount of drug is administered or dispensed from the chamber (e.g., via an outlet port) into a liquid passage extending between the pump and the cannula in the patient.

[0028] For illustrative purposes, reference is made to an exemplary rotary metering pump described in Common-Owned Patent Document 1, the contents of which are incorporated herein by reference in their entirety. Referring to Figures 1, 2, 3A, 3B, and 3C, an exemplary infusion pump (e.g., a wearable drug delivery device such as an insulin patch pump) comprises a pump assembly 20 connectable to a DC motor and a gearbox assembly (not shown) that rotates a sleeve 24 in a pump manifold 22. The sleeve is provided with a helical groove 26. A coupling pin 28 connected to a piston 30 moves parallel along the helical groove to guide the retraction and insertion of the piston 30 into the sleeve 24, respectively, as the sleeve 24 rotates in one direction and then in the opposite direction. The sleeve has an end plug 34. Two seals 32, 36 at the piston and the respective ends of the end plug within the sleeve 24 define a cavity or chamber 38 when the piston 30 retracts following the suction stroke and is therefore ready for discharge, as shown in Figure 3A. Therefore, the volume of chamber 38 changes depending on the degree of retraction of the piston 30. As shown in Figure 3B, when the piston 30 is fully inserted and the seals 32, 36 are substantially in contact with each other after the discharge stroke, and therefore ready for aspiration, the volume of chamber 38 is negligible or substantially zero. Two ports 44, 46 are provided on the pump manifold 22. Through the inlet port 44, it is possible for the drug to flow from the reservoir 70 (Figure 4A) for the pump 64 (Figure 4A). Through the outlet port 46, the drug drawn into chamber 38 can be discharged from chamber 38 into a fluid passage, for example, a cannula 72 (Figure 4A) in the patient, by reinserting the piston 30 into chamber 38.

[0029] Continuing to refer to Figures 1, 2, 3A, 3B, and 3C, the sleeve 24 may be provided with an opening (not shown) that allows the drug in the chamber 38 to flow through the corresponding one of the ports 44, 46, aligned with either the outlet port 46 or the inlet port 44 (i.e., depending on the degree of rotation of the sleeve 24, and therefore the degree of translation of the piston 30). A pump measuring device 78 (Figure 4A) may be provided, for example, a sleeve rotation limiting switch having an interlock 42 and one or more detents 40 on the sleeve 24 or its end plug 34 cooperating with the interlock 42. The interlock 42 can be attached to the manifold 22 at each of its ends. The detents 40 on the end face of the sleeve 24 are adjacent to the bump 48 of the interlock 42 when the pump 64 is in a first position, thereby aligning the side hole of the sleeve 24 with the inlet port 44 to receive liquid from the reservoir 70 into the chamber 38. Under certain conditions, such as back pressure, friction between the piston 30 and the sleeve 24 may be sufficient to rotate the sleeve 24 before the piston 30 and coupling pin 28 reach either end of the helical groove 26. This could result in an incomplete volume of fluid being pumped per stroke. To prevent such a situation, the interlock 42 prevents the sleeve 24 from rotating until the torque exceeds a predetermined threshold, as shown in Figure 3A. This ensures that the piston 30 rotates completely within the sleeve until the coupling pin reaches the end of the helical groove 26. Once the coupling pin 28 hits the end of the helical groove 26, further movement by the DC motor and gearbox assembly or other types of pump and valve actuators 66 (Figure 4A) increases the torque of the sleeve 24 beyond the threshold, causing the interlock 42 to bend and allowing the stopper 40 to pass the bump 48. When the sleeve 24 has finished rotating so that the side hole of the sleeve 24 is aligned with the cannula 72 or the outlet port 46, the stopper 40 moves through the bump 48 of the interlock 42, as shown in Figure 3B.It is also possible to provide another sleeve mechanism 41 that engages with an electrical switch (for example, an endstop switch 90 provided on the printed circuit board 92 and positioned relative to the sleeve and / or end plug 34 to cooperate with the pump measuring device 78 as shown in Figure 3C).

[0030] Figure 4A is a system diagram showing exemplary components of an exemplary drug delivery device 10 having an infusion pump, such as the pumps in Figures 1, 2, 3A, 3B, and 3C. The drug delivery device 10 may include an electronics subsystem 52 for controlling the operation of components in the liquid subsystem 54, such as a pump 64, and an insertion mechanism 74 for positioning a cannula 72 for insertion into the injection site in the patient's skin. A power storage subsystem 50 may include, for example, a battery 56 for supplying power to the components in the electronics subsystem 52 and the liquid subsystem 54. The liquid subsystem 54 may have an optional infusion port 68 to fill a reservoir 70 (e.g., with drug), although the drug delivery device 10 may optionally be transported from the manufacturer with the reservoir already filled. The liquid subsystem 54 also has a measuring subsystem 62 including a pump 64 and a pump actuator 66. As described above, the pump 64 may have two ports 44, 46 and associated valve subassemblies that control when liquid enters and exits the pump chamber 38 through the respective ports 44, 46. One of the ports is, for example, an inlet port 44 through which liquid, such as a liquid medicine, flows from the reservoir 70 into the pump 64 as a result of a pump suction or pull stroke against the pump plunger or piston 30. The other port is an outlet port 46 through which the liquid flows out of the pump chamber 38 and flows toward the cannula 72 for administration to the patient pump as a result of a pump discharge or push stroke of the pump plunger or piston 30. The microcontroller 58 may be provided with an integrated or separate memory device having computer software instructions, for example, to rotate the sleeve 24 in a selected direction, to move the piston 30 within the sleeve 24 in a parallel or axial direction for a suction or discharge stroke, and optionally to rotate the sleeve 24 and piston 30 together during a valve state change, as described in Patent Document 1.As described below, the microcontroller 58, which monitors pump parameter measurements and detects when an empty reservoir state occurs in relation to the infusion pump, can be equipped with an empty reservoir algorithm according to an exemplary embodiment.

[0031] Figure 4B shows an exemplary apparatus for motor current sensing. By adding a sensing register 142 to the PCB 92, motor current can be measured. The voltage drop across the sensing register 142 is fed to the analog-to-digital converter (ADC) of the microcontroller 58. The microcontroller 58 then calculates the blockage state, and if a specified characteristic property of the blocked or empty reservoir motor current is detected, for example, the blocked or empty reservoir event is reported by the microcontroller 58. Other components can be used for current sensing to facilitate pump motor current measurement. For example, a pulse-width modulation (PWM) driven motor can be used as the pump actuator 66 to estimate motor current information from PWM data.

[0032] Figure 5 shows pump measurement data from an exemplary delivery device, illustrating the change in motor current during administration at different pressures (e.g., 6 psi, 30 psi, 70 psi). As can be seen from Figure 5, the pump measurement data has a somewhat consistent waveform (e.g., spikes 144 and 146 corresponding to the motor start-up and stroke-end interlock operation at the beginning of the stroke), but shows that the motor current level increases as the pressure increases, as roughly indicated by reference numeral 148. Thus, the motor current waveform can reflect pressure changes from a blocked or empty reservoir state, as described above.

[0033] Figures 6A and 6B show raw and filtered pump measurement data (e.g., motor current) from an exemplary delivery device during the suction and discharge strokes, respectively. As shown in Figures 6A and 6B, waveform shapes or spikes 144 and 146 can be seen in both the suction and discharge strokes, and regardless of whether the pump measurement data is raw or filtered.

[0034] Figures 7A and 7B show the changes in pump motor current during suction after the pump reservoir is empty (e.g., during the suction stroke in the exemplary pumps shown in Figures 1, 2, and 3A-3C), respectively. Figure 7A shows filtered pump measurement data, including the measured motor current for a series of suction strokes when liquid remains in the reservoir 70. Figure 7B shows the changes in filtered pump measurement data, including the measured motor current for a series of suction strokes when the reservoir 70 is empty, particularly the changes in the waveform portion 148 between motor current spikes 144 and 146 that occur during motor operation in response to interlocks at startup and stroke end. For example, when the reservoir 70 is empty, the motor current increases to between approximately 22-30 mA, as shown in Figure 7B, compared to the motor current level when the reservoir 70 is not empty, which is approximately 10-21 mA, as shown in Figure 7A. Figure 7B also shows that in the latter half 148b of portion 148 of the motor current waveform during the suction stroke, there is an increase in motor current indicating the occurrence of an empty reservoir state.

[0035] Figure 8 shows pump measurement data (e.g., motor current) from an exemplary delivery device over several suction strokes, and point 150 in the measured motor current data indicating an empty reservoir. By using a relatively simple averaging scheme (i.e., without using additional criteria to identify changes in the shape of the measured data waveform), Figure 8 shows that the empty reservoir point 150 is relatively easily identifiable in the pump measurement data, depending solely on the suction motor current.

[0036] According to exemplary embodiments of this disclosure, criteria for detecting an empty reservoir state (e.g., thresholds and other criteria such as changes in the waveform shape of the measured data) are established using an empty reservoir detection algorithm in the control software of the infusion pump. The exemplary motor current data waveforms shown in Figures 5, 6A, 6B, 7A, 7B, and 8 are waveforms for a particular type of infusion pump, and it should be understood that the pump measurement data and the criteria for detecting an empty reservoir state may vary based on the pump type, the type of fluid to be delivered, the amount of fluid to be delivered, ambient temperature, ambient pressure or other environmental considerations, and other factors. For example, as mentioned above, the pump measurement data may be, but are not limited to, any of the following pump operating parameters: motor current, motor voltage, motor drive time, motor coasting time, delivery pulse energy, motor drive count, motor coasting count, and delta encoder count. Furthermore, the measured parameters may be characteristics of these signals or combinations of characteristics from different signals. Criteria for detecting an empty reservoir can be determined experimentally, for example, by testing a specific infusion pump, reservoir, and fluid setup, identifying patterns in the measured pump parameter test data, and specifying pattern-based criteria for use by an empty reservoir detection algorithm.

[0037] Figure 9 is a flowchart illustrating an example of the operation of an exemplary drug delivery device according to an exemplary embodiment of the present invention. The microcontroller 58 or other processing device controlling the pump operation starts aspiration (e.g., aspiration stroke) according to an empty reservoir detection algorithm (block 160) and starts acquiring pump measurement data during aspiration (block 162). The microcontroller 58 analyzes the pump measurement data (block 164) and determines whether a specified empty reservoir criterion is met (block 166). The criterion can be determined experimentally, for example, using a given pump, liquid, reservoir size, and liquid delivery volume test. The criterion may include a selected threshold or range of measured pump data values ​​that indicate the pressure rise associated with an empty reservoir. For example, averaging multiple measurement data points and setting the averaged pump measurement data value or the value of each data point over a given aspiration period to a threshold T EMPTY It is possible to compare this. The analysis in block 164 may also include the waveform shape or area under curve analysis of selected portions of the pump measurement data obtained during suction in order to determine whether other criteria (e.g., shape-related criteria such as slope, curved area, etc.) are met and an empty reservoir state is indicated. For example, as described above, the microcontroller 58 has a threshold T of 22mA or higher than 22mA. EMPTY It is possible to program the system to focus on pump measurement data in the latter half of the suction stroke, exceeding a certain threshold. The microcontroller 58 can also analyze some suction strokes differently from others, taking into account motor drive time, or the number of suction strokes, or the estimated amount of fluid delivered, to determine whether the empty reservoir condition criterion is met. For example, the microcontroller 58 can be configured to ignore one or more pump measurements obtained in one or more parts of the suction operation period characterized by a transient increase from the normal operation of the pump mechanism.

[0038] Continuing to refer to Figure 9, if the empty reservoir condition criterion is not met (block 166) and aspiration is not yet complete (block 168), the microcontroller 58 then continues to acquire pump measurement data (block 162) and continues to analyze the pump measurement data (block 164). On the other hand, once aspiration is complete (block 168) and the intended liquid delivery is complete (block 170), the drug delivery device can then be powered off and / or replaced, depending on the type of pump or reservoir it uses. Alternatively, in the case of a metering reciprocating pump having alternating aspiration and discharge strokes to deliver incremental amounts of liquid into the metering chamber 38, completion of delivery (block 170) can refer to the delivery of incremental amounts of liquid into the metering chamber 38, and the microcontroller can wait until another discharge stroke occurs before initiating another aspiration stroke (block 160).

[0039] Continuing to refer to Figure 9, if the empty reservoir condition criterion is met (block 166), additional pump measurement data (block 172) may need to be acquired (block 162) and analyzed (block 164) for other thresholds or waveform shape-related metrics and / or other parts of aspiration before it is possible to determine whether the reservoir is empty or has reached the end of its life (EOL). If additional pump measurement data is not needed, the microcontroller 58 can stop the pump by the empty reservoir detection algorithm (block 176), thereby avoiding dose inaccuracies due to over-pumping. On the other hand, if aspiration is incomplete and additional pump measurement data is needed, the microcontroller 58 is programmed to continue acquiring (block 162) and analyzing (block 164) the pump measurement data.

[0040] Equivalent matters can also be calculated based on other measurable characteristics of the electrical system. For example, it is possible to measure the motor voltage instead of, or in addition to, the motor current, and the motor voltage is characterized by a change in shape similar to the characteristics shown in Figure 7B when the reservoir is empty. This is because as the motor decelerates, more current is drawn in, and the motor's back electromotive force and impedance decrease. The decrease in impedance increases the current flowing through the motor. At the same time, the voltage source has some internal resistance (impedance). This impedance crossing the motor changes on a similar scale to the battery's impedance, so the voltage drop seen with respect to the battery also changes.

[0041] As mentioned above, a typical solution for detecting an empty reservoir is to place an additional sensor within the pump control system and report the empty reservoir status when detected by the sensor. However, adding a sensor comes with drawbacks such as increased system complexity (e.g., mechanical, electrical, and / or software complexity), increased system power consumption, and / or increased pump costs. These drawbacks can be particularly disadvantageous for wearable pump designs where all or part of the pump is intended to be disposable once the reservoir 70 is empty, or the pump 64 has been used for a selected time, and / or the pump 64 has been used to deliver a selected amount of drug.

[0042] According to an exemplary embodiment, empty reservoir detection is achieved without adding any components. Alternatively, a microcontroller 58 or other processing device for controlling pump operation may be further controlled to determine if motor parameter measurements are outside a specified range for normal operation, indicating an empty reservoir (e.g., meeting a predetermined threshold or other criterion), terminating pump operation, and optionally generating an empty reservoir status indicator. The pump reservoir 70 and / or the entire drug delivery device 10 can be replaced sequentially, thereby ensuring that the patient receives the full dose intended to be provided under normal operating conditions.

[0043] Those skilled in the art will understand that the application of this disclosure is not limited to the structural details and arrangement of components described above or illustrated in the drawings. The embodiments described herein are not limited to other embodiments and can be carried out or implemented in various ways. Furthermore, it will be understood that the expressions and terms used herein are for illustrative purposes only and should not be considered limiting. The use of “includes,” “equipped,” or “has,” and their variations herein, means to include additional items in addition to the items and their equivalents listed thereafter. Unless specifically limited, the terms “connected,” “joined,” and “installed,” and their variations herein, are used broadly and include direct and indirect connections, combinations, and installations. Furthermore, the terms “connected,” and “joined,” and their variations, are not limited to physical or mechanical connections or combinations. Additionally, terms such as top, bottom, base, and upper surface are relative and used to aid in illustration, but are not limiting.

[0044] The components of the illustrated apparatus, system, and method adopted according to the illustrated embodiments can be implemented, at least in part, as digital electronic circuits, analog electronic circuits, or computer hardware, firmware, software, or a combination thereof. These components can be implemented as computer program products, such as computer programs, program code, or computer instructions, clearly embodied in an information medium or machine-readable storage device for execution by or control of data processing devices such as a programmable processor, computer, or multiple computers.

[0045] Computer programs may be written in any form of programming language, including compiled or interpreted languages, and may be deployed in any form, including as standalone programs or as modules, components, subroutines, or other units suitable for use in a computing environment. Computer programs may be arranged to run on one computer or multiple computers at one site, or they may be distributed across multiple sites and interconnected by a communication network. Furthermore, functional programs, code, and code segments for achieving exemplary embodiments can be readily interpreted by a programmer skilled in the art to which the exemplary embodiments belong as being within the scope of the claims illustrated by the exemplary embodiments. Method steps relating to exemplary embodiments of the present invention can be performed by one or more programmable processors that execute computer programs, code, or instructions for performing functions (e.g., by manipulating input data and / or generating outputs). For example, method steps may also be performed by special-purpose logic circuits such as FPGAs (Field-Programmable Gate Arrays) or ASICs (Application-Specific Integrated Circuits), and the apparatus of the exemplary embodiments can be implemented in this manner.

[0046] Various exemplary logic blocks, modules, and circuits described in relation to embodiments disclosed herein may be implemented or run by a general-purpose processor, a digital signal processor (DSP), an ASIC, an FPGA, or other programmable logic device, individual gates, or transistor logic, individual hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but alternatively, a processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors combined with a DSP core, or other such configurations.

[0047] Processors suitable for executing computer programs include, for example, both general-purpose and special-purpose microprocessors, and any one or more processors in any type of digital computer. Generally, processors receive instructions and data from read-only memory, random-access memory, or both. Essential elements of a computer are the processor for executing instructions and one or more memory devices for storing instructions and data. Generally, a computer also includes one or more mass storage devices for storing data, such as magnetic, magneto-optical, or optical disks, or is operablely coupled to them to receive or transfer data, or both. Information media suitable for embodying computer program instructions and data include, for example, electrically programmable read-only memory or ROM (EPROM), electrically erasable programmable ROM (EEPROM), semiconductor memory devices such as flash memory devices, and all forms of non-volatile memory, including data storage disks (magnetic disks, internal hard disks, or removable disks, magneto-optical disks, CD-ROMs, and DVD-ROMs). Processors and memory can be complemented or incorporated by special-purpose logic circuits.

[0048] Those skilled in the art will understand that information and signals can be represented using any of a variety of different techniques and methods. For example, data, instructions, commands, information, signals, bits, symbols, and chips, which may be referenced throughout the above description, may be represented by voltage, electric current, electromagnetic waves, magnetic fields or magnetic particles, optical fields or light particles, or any combination thereof.

[0049] Those skilled in the art will further understand that various exemplary logic blocks, modules, circuits, and algorithmic steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or a combination of both. To clearly demonstrate this hardware- and software compatibility, various exemplary components, blocks, modules, circuits, and steps have been generally described in terms of their function. Whether such functions are implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system. Those skilled in the art may implement the described functions in various ways for specific applications, but such decisions on implementation should not be construed as resulting in a departure from the claims illustrated by the exemplary embodiments. Software modules may reside in random access memory (RAM), flash memory, ROM, EPROM, EEPROM, registers, hard disks, removable disks, CD-ROMs, or any other form of storage medium known in the art. The exemplary storage medium is coupled to the processor so that the processor can read information from and write information to the storage medium. Alternatively, the storage medium may be integrated into the processor. In other words, the processor and storage medium can reside within an integrated circuit or be implemented as separate components.

[0050] Computer-readable non-temporary media include all types of computer-readable media, including magnetic storage media, optical storage media, flash media, and solid-state storage media. It should be understood that software can be installed on a central processing unit (CPU) device and sold. Alternatively, software can be acquired and loaded onto a CPU device, which includes acquiring the software through physical media or distribution systems, for example, from a server owned by the software creator, or from a server used by the software creator but not owned by them. Software can also be stored on a server for distribution, for example, over the internet.

[0051] The above description and figures are intended for illustrative purposes only and are not intended to limit the invention in any way except as described in the following claims. Those skilled in the art should note that various technical aspects of various elements of the various exemplary embodiments described above can be readily combined in many other ways, all of which are considered to be within the scope of the claims.

Claims

1. A pump comprising a liquid chamber and a pump mechanism configured to control the amount of liquid drawn from a reservoir to the chamber during a suction operation and the discharge of the liquid from the chamber during a discharge operation, A processing device configured to analyze one or more pump measurement values ​​obtained during a selected portion of the suction operation period, and to determine when the one or more pump measurement values ​​meet a specified criterion related to the empty reservoir state of the reservoir, Equipped with, An infusion device wherein the duration of the suction operation is characterized by a first time period and a remaining time period following the first time period, and the selected portion of the duration of the suction operation falls within the remaining time period of the duration of the suction operation.

2. The infusion device according to claim 1, wherein the processing device is configured to analyze data selected from the driving time of the motor in the pump mechanism, the number of suction operations performed by the pump, and the estimated amount of fluid delivered by the pump, and is configured to analyze some suction operations in a different manner from other suction operations based on the data when determining whether the condition that the reservoir is empty is met.

3. The infusion device according to claim 1, wherein the processing device is configured to analyze additional pump measurements when one or more pump measurements satisfy the specified criteria, and to determine when the additional pump measurements satisfy the specified criteria before the termination operation of the pump mechanism.

4. The infusion device according to claim 3, wherein the processing device is configured to terminate the operation of the pump mechanism when the additional pump measurement value meets the specified criterion.

5. The infusion device according to claim 1, wherein the pump measurement value is selected from one or more pump motor current, pump motor voltage, pump encoder count, pump motor drive count, and pump motor drive time.

6. The infusion device according to claim 1, wherein the processing device is configured to ignore the one or more pump measurements obtained during the selected partial period if the one or more pump measurements are characterized by a transient increase resulting from the normal operation of the pump mechanism.

7. The infusion device according to claim 1, wherein the designated criteria further include one or more criteria selected from a range of pump measurement values ​​indicating a pressure exceeding the normal operating pressure of the pump, and designated signal waveforms corresponding to the pump measurement values ​​indicating a pressure exceeding the normal operating pressure of the pump.

8. The infusion device according to claim 1, wherein the processing device is configured to terminate the operation of the pump mechanism if one or more pump measurements obtained during the selected partial period of the suction operation meet the specified criteria.

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