Patent ID: 12194304

Like reference characters denote like elements throughout the description and figures.

DETAILED DESCRIPTION

Implantable medical devices (IMDs) can sense and monitor signals and use those signals to determine various conditions of a patient and/or provide therapy to the patient. Example IMDs include monitors, such as the Reveal LINQ™ Insertable Cardiac Monitor, available from Medtronic, PLC, of Dublin, Ireland. Such IMDs may facilitate relatively longer-term monitoring of patients during normal daily activities, and may periodically transmit collected data to a network service, such as the Medtronic CareLink® Network, developed by Medtronic, PLC, or some other network linking patient4to a clinician.

FIG.1illustrates the environment of an example medical system2in conjunction with a patient4, in accordance with one or more techniques of this disclosure. Patient4ordinarily, but not necessarily, will be a human. For example, patient4may be an animal needing ongoing monitoring for cardiac conditions. System2includes IMD10. IMD10may include one or more electrodes (not shown) on a housing of IMD10, or may be coupled to one or more leads that carry one or more electrodes. System2may also include external device12.

The example techniques may be used with an IMD10, which may be configured to be in wireless communication with at least one of external device12and other devices not pictured inFIG.1. In some examples, IMD10may be implanted within patient4. For example, IMD10may be implanted outside of a thoracic cavity of patient4(e.g., pectoral location illustrated inFIG.1). In some examples, IMD10may be positioned near the sternum near or just below the level of the heart of patient4, e.g., at least partially within the cardiac silhouette.

In some examples, IMD10may sense cardiac electrogram (EGM) signals via the plurality of electrodes and/or operate as a therapy delivery device. For example, IMD10may operate as a therapy delivery device to deliver electrical signals to the heart of patient4, such as an implantable pacemaker, a cardioverter, and/or defibrillator, a drug delivery device that delivers therapeutic substances to patient4via one or more catheters, or as a combination therapy device that delivers both electrical signals and therapeutic substances.

In some examples, system2may include any suitable number of leads coupled to IMD10, and each of the leads may extend to any location within or proximate to a heart or in the chest of patient4. For example, other examples therapy systems may include three transveous leads and an additional lead located within or proximate to a left atrium of a heart. As other examples, a therapy system may include a single lead that extends from IMD10into a right atrium or right ventricle, or two leads that extend into a respective one of a right ventricle and a right atrium.

In some examples, IMD10takes the form of the Reveal LINQ™ Insertable Cardiac Monitor (ICM), or another ICM similar to, e.g., a version or modification of, the LINQ™ ICM, available from Medtronic PLC. Such IMDs may facilitate relatively longer-term monitoring of patients during normal daily activities, and may periodically transmit collected data to a network service, such as the Medtronic CareLink® Network.

External device12may be a computing device with a display viewable by a user and an interface for providing input to external device12(i.e., a user input mechanism). The user may be a physician technician, surgeon, electrophysiologist, clinician, or patient4. In some examples, external device12may be a notebook computer, tablet computer, computer workstation, one or more servers, cellular phone, personal digital assistant, handheld computing device, networked computing device, or another computing device that may run an application that enables the computing device to interact with IMD10. For example, external device12may be a clinician, physician, or user programmer configured to communicate wirelessly with IMD10and perform data transfers between external device12and IMD10. External device12is configured to communicate with IMD10and, optionally, another computing device (not illustrated inFIG.1), via wired or wireless communication. External device12, for example, may communicate via near-field communication (NFC) technologies (e.g., inductive coupling, NFC or other communication technologies operable at ranges less than 10-20 cm) and far-field communication technologies (e.g., Radio Frequency (RF) telemetry according to the 802.11 or Bluetooth® specification sets, or other communication technologies operable at ranges greater than near-field communication technologies). In some examples, external device12may include a programming head that may be placed proximate to the body of patient4near the IMD10implant site in order to improve the quality or security of communication between IMD10and external device12. In some examples, external device12may be coupled to external electrodes, or to implanted electrodes via percutaneous leads.

In some examples, the user may use external device12to program or otherwise interface with IMD10. External device12may be used to program aspects of sensing or data analysis performed by IMD10and/or therapies provided by IMD10. In addition, external device12may be used to retrieve data from IMD10. The retrieved data may include cardiac EGM segments recorded by IMD10, e.g., due to IMD10determining that an episode of arrhythmia or another malady occurred during the segment, or in response to a request to record the segment from patient4or another user. In other examples, the user may also use external device12to retrieve information from IMD10regarding other sensed physiological parameters of patient4, such as activity, temperature, tissue impedance, intrathoracic impedance, or posture. Additionally, one or more remote computing devices may interact with IMD10in a manner similar to external device12, e.g., to program IMD10and/or retrieve data from IMD10, via a network.

Processing circuitry of IMD10may be configured to perform the example techniques of this disclosure for using internal sensors to determine when to switch operational modes of IMD10. For example, as described in greater detail elsewhere in this disclosure, the processing circuitry of IMD10may analyze temperature values and other values sensed by IMD10(e.g., impedance values or heart rate values) to determine whether IMD10is implanted. The determination of whether IMD10is implanted may be used to switch the IMD from a first mode to a second mode.

In some examples, IMD10may use a temperature relative to IMD10in order to make a first preliminary determination that IMD10is implanted, e.g., when a temperature satisfies a temperature criterion. In some examples, IMD10may obtain temperature data via one or more temperature sensing device(s) disposed within or otherwise fixed to IMD10, such as fixed to the outer housing of IMD10or with temperature probes/leads entering into and/or extending out of IMD10. The temperature values monitored by IMD10may be raw temperature data sampled by IMD10, or in some instances, post-processed temperature data, such as smoothened temperature data that has been conditioned by a particular signal processing techniques (e.g., low-pass filter, high-pass filter, band-pass filter, band-stop filter, etc.).

In response to the first preliminary determination being that IMD10is implanted, the processing circuitry of IMD10may cause IMD10to evaluate an impedance or an heart rate. IMD10may use the impedance or the heart rate to make a second preliminary determination of whether IMD10is implanted. For example, IMD10may include an impedance sensor configured to provide an electrical signal to fluid and/or tissue of patient4between a first electrode and a second electrode. When IMD is implanted into fluid and/or tissue of patient4, a path between the two electrodes may have a corresponding impedance. The processing circuitry of IMD10may receive signals indicative of the corresponding impedance and may make a second preliminary determination of whether IMD10is implanted, e.g., when the impedance satisfies an impedance criterion. As another example, IMD10may include an electrocardiography (ECG) sensor configured to monitor heart activity of patient4and the processing circuitry of IMD10may receive signals indicative of heart rate of patient4and may make a second preliminary determination of whether IMD10is implanted, e.g., when the heart rate satisfies an heart rate criterion.

Depending on both the first preliminary determination and the second preliminary determination, the processing circuitry of IMD10may determine whether IMD10is implanted and may switch IMD10from a first mode to a second mode based on the determination. In some examples, IMD10may be switched from a dormant mode, e.g., a mode does not include communication with an external computing device, to an activated mode, e.g., a mode include communication with an external computing device.

In examples in which IMD10also operates as a pacemaker, a cardioverter, and/or defibrillator, or otherwise monitors the electrical activity of the heart, IMD10may sense electrical signals attendant to the depolarization and repolarization of the heart of patient4via electrodes coupled to at least one lead. In some examples, IMD10can provide pacing pulses to the heart of patient4based on the electrical signals sensed within the heart of patient4. IMD10may also provide defibrillation therapy and/or cardioversion therapy via electrodes located on at least one lead, as well as a housing electrode. IMD10may detect arrhythmia of the heart of patient4, such as fibrillation of ventricles, and deliver defibrillation therapy to the heart of patient4in the form of electrical pulses.

Although described primarily in the context of examples in which IMD10is an insertable cardiac monitor, the techniques described herein may be implemented by medical device systems including any one or more implantable or external medical devices, such as any one or more monitors, pacemakers, cardioverters, defibrillators, heart assist devices, such as left-ventricular assist devices, neurostimulators, or drug delivery devices.

FIG.2is a functional block diagram illustrating an example configuration of IMD10ofFIG.1in accordance with one or more techniques described herein. In the illustrated example, IMD10includes electrodes16A-16N (collectively, “electrodes16”), communication system26, processing circuitry50, sensing circuitry52, storage device60, switching circuitry58, sensor(s)62, and power source91.

Processing circuitry50may include fixed function circuitry and/or programmable processing circuitry. Processing circuitry50may include any one or more of a microprocessor, a controller, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or equivalent discrete or analog logic circuitry. In some examples, processing circuitry50may include multiple components, such as any combination of one or more microprocessors, one or more controllers, one or more DSPs, one or more ASICs, or one or more FPGAs, as well as other discrete or integrated logic circuitry. The functions attributed to processing circuitry50herein may be embodied as software, firmware, hardware or any combination thereof.

Sensing circuitry52may monitor signals from sensor(s)62, which may include one or more temperature sensor(s)63, accelerometers, pressure sensors, and/or optical sensors, as examples. Any suitable temperature sensor(s)63may be used to detect temperature or changes in temperature. In some examples, temperature sensor(s)63may include a thermocouple, a thermistor, a junction-based thermal sensor, a thermopile, a fiber optic detector, an acoustic temperature sensor, a quartz or other resonant temperature sensor, a thermo-mechanical temperature sensor, a thin film resistive element, etc.

In some examples, sensing circuitry52may include one or more filters and amplifiers for filtering and amplifying signals received from temperature sensor(s)63and/or electrodes16. For example, sensing circuitry52may include one or more low-pass filters having various cutoff frequencies predefined to apply to temperature values obtained from temperature sensor(s)63, such as from one or more temperature sensors. In some examples, sensing circuitry52may include circuitry configured to digitally filter measured temperature values using one or more cutoff frequencies, or otherwise using one or more different filtering processes to achieve different degrees of smoothing of a series of temperature values. For example, sensing circuitry52may include certain processing circuitry configured to smooth temperature values determined over time to create smoothened temperature signals. In some examples, sensing circuitry52may perform smoothing of temperature values measured by temperature sensor(s)63, such that processing circuitry50may perform various other techniques of this disclosure based on the smoothened temperature signals. In some examples, processing circuitry50may be configured to smooth temperature values determined over time to create smoothened temperature signals (e.g., by performing digital and/or analog filtering).

In some examples, sensing circuitry52may be selectively coupled to electrodes16via switching circuitry58(e.g., to select the electrodes16and polarity) in order to sense impedance and/or cardiac signals. Sensing circuitry52may sense signals from electrodes16, e.g., to produce a cardiac EGM or subcutaneous electrocardiogram, in order to facilitate monitoring electrical activity of the heart.

Processing circuitry50may cause sensing circuitry52to periodically measure a physiological parameters or other parameter values of IMD10, such as temperature values. For temperature measurements, processing circuitry50may control sensing circuitry52to obtain a temperature measurement via one or more temperature sensor(s)63. Because IMD10may be configured to include sensing circuitry52, sensing circuitry may be implemented in one or more processors, such as processing circuitry50of IMD10. Similar to processing circuitry50,80,98and other circuitry described herein, sensing circuitry52may be embodied as one or more hardware modules, software modules, firmware modules, or any combination thereof.

In some examples, processing circuitry50may receive temperature measurements from one or more temperature sensor(s)63via sensing circuitry52in order to make a first preliminary determination of whether IMD10is implanted. In some examples, processing circuitry50may control the timing of temperature measurements based on a schedule. For example, processing circuitry50may control the measurement of temperature values on a periodic basis, such as on an hourly or per-minute basis. In one example, temperature sensor(s)63may measure temperature values during a particular portion of a day. As an example, temperature sensor(s)63may measure temperature values every twenty minutes for a predetermined number of hours, such as between 8 am and 5 pm. Processing circuitry50may determine a measured temperature value by calculating an average of measurements. In this case, the value may be the average of the temperature values measured by temperature sensor(s)63during a scheduled measurement period (e.g., a number of measurements taken during one minute each half-hour).

In some examples, sensing circuitry52may be configured to sample temperature measurements at a particular sampling rate. In such examples, sensing circuitry52may be configured to perform downsampling of the received temperature measurements. For example, sensing circuitry52may perform downsampling in order to decrease the throughput rate for processing circuitry50. This may be particularly advantageous where sensing circuitry52has a high sampling rate when active.

As used herein, the term “temperature value” is used in a broad sense to indicate any collected, measured, and/or calculated value. In some examples, temperature values are derived from temperature signals received from one or more temperature sensor(s)63. For example, temperature values may include an average (e.g., mean, mode, standard deviation) of temperature signals received from one or more temperature sensor(s)63.

Once processing circuitry50determines a temperature, processing circuitry50may make a first preliminary determination of whether IMD10is implanted based on the temperature. For example, processing circuitry50may determine whether or not the temperature satisfies temperature criterion64as stored in storage device60.

One or more biosensor(s)53of sensing circuitry52may be configured to detect activity (e.g., electrical or mechanical activity of the heart or other tissue of patient4) or impedance from a patient4.

In some examples, biosensor(s)53may include an impedance sensor. In response to a first preliminary determination being that IMD10is implanted, processing circuitry50may receive impedance measurements from one or more biosensor(s)53of sensing circuitry52and may make a second preliminary determination of whether IMD10is implanted based on the received impedance measurements. In some examples, processing circuitry50controls biosensor(s)53to perform one or more impedance measurements in response to the first preliminary determination being that IMD10is implanted.

In some examples, processing circuitry50may be configured to identify and analyze an impedance of the electrical signal sent by biosensor(s)53through an electrical path including at least two of electrodes16. As described herein, an impedance may change depending upon a location of IMD10. For example, an impedance may decrease when IMD10is implanted into tissue and/or fluid of patient4. Once processing circuitry50determines an impedance, processing circuitry50may a second preliminary determination of whether IMD10is implanted. For example, processing circuitry50may determine whether or not the impedance satisfies impedance criterion66as stored in storage device60.

In some examples, biosensor(s)53may include an ECG senor configured to receive electrical signals representing the electrical activity of heart via electrodes16, and detect a heart rate of patient4. In response to a first preliminary determination being that IMD10is implanted, processing circuitry50may receive a signal indicating heart activity from one or more biosensor(s)53of sensing circuitry52and may make a second preliminary determination of whether IMD10is implanted based on the received signal. In some examples, processing circuitry50turn on biosensor(s)53to monitor heart activity of patient4in response to the first preliminary determination being that IMD10is implanted. Processing circuitry50may identify a heart rate from the received signal and may determine whether or not the heart rate satisfies heart rate criterion68as stored in storage device60. Since performance of detection by biosensor(s)53may consume power, activation of biosensor(s)53for monitoring in response to the first preliminary determination being that IMD10is implanted may conserve power source91of IMD10.

In the example illustrated inFIG.2, processing circuitry50is capable of performing the various techniques described with reference toFIGS.6-11. In various examples, processing circuitry50may perform one, all, or any combination of the plurality of techniques discussed in greater detail below.

Sensing circuitry52may provide one or more temperature, impedance, and heart rate values to processing circuitry50for analysis, e.g., for analysis to determine when to switch IMD10from a first mode to a second mode according to the techniques of this disclosure. In some examples, processing circuitry50may store the temperature, impedance, and heart rate values to storage device60. Processing circuitry50of IMD10may analyze the temperature, impedance, and heart rate values to determine whether IMD10is implanted according to the techniques of this disclosure. The determination of whether IMD10is implanted may be used to switch the IMD from a first mode to a second mode.

Communication system26may include any suitable hardware, firmware, software or any combination thereof for communicating with another device, such as external device12, another networked computing device, or another IMD or sensor. Under the control of processing circuitry50, communication system26may receive downlink telemetry from, as well as send uplink telemetry to external device12or another device with the aid of an internal or external antenna. In addition, processing circuitry50may communicate with a networked computing device via an external device (e.g., external device12) and a computer network, such as the Medtronic CareLink® Network. Communication system26may be configured to transmit and/or receive signals via inductive coupling, electromagnetic coupling, near-field communications, RF communication, Bluetooth®, WI-FI™, or other proprietary or non-proprietary wireless communication schemes. For example, processing circuitry50may provide data to be uplinked to external device12via communication system26and control signals using an address/data bus. In some examples, communication system26may provide received data to processing circuitry50via a multiplexer.

In some examples, as illustrated byFIG.2, communication system26may be selectively coupled to electrodes16by switching circuitry58. In such examples, communication system26may be configured to communicate with external device12or another computing devices external to patient4via tissue conductance communication (TCC). In some examples, e.g., as described with respect toFIG.9, processing circuitry50may be configured to switch IMD10from the first mode to the second mode in response to communication circuitry26receiving a predetermined signal, e.g., a “wake-up” signal, from external device12via electrodes16. The signal may have time-varying frequency and/or amplitude changes that occur in a predetermined pattern detectable by processing circuitry50. In some examples, in response to a first preliminary determination being that IMD10is implanted, processing circuitry50may activate communication circuitry26to the extent necessary to enable receipt of the wake-up signal via electrodes16.

In some examples, storage device60includes computer-readable instructions that, when executed by processing circuitry50, cause IMD10and processing circuitry50to perform various functions attributed to IMD10and processing circuitry50herein. Storage device60may include any volatile, non-volatile, magnetic, optical, or electrical media. For example, storage device60may include random access memory (RAM), read-only memory (ROM), non-volatile RAM (NVRAM), electrically-erasable programmable ROM (EEPROM), erasable programmable ROM (EPROM), flash memory, or any other digital media. Storage device60may store, as examples, programmed values for one or more operational parameters of IMD10and/or data collected by IMD10for transmission to another device using communication system26. Data stored by storage device60and transmitted by communication system26to one or more other devices may include cardiac electrical or mechanical data, impedance values, heart rate values, or temperature values.

The various components of IMD10are coupled to power source91, which may include a rechargeable or non-rechargeable battery. A non-rechargeable battery may be capable of holding a charge for several years, while a rechargeable battery may be inductively charged from an external device, such as external device12, on a daily, weekly, or annual basis, for example.

FIG.3is a conceptual side-view diagram illustrating an example configuration of IMD10ofFIG.1. In the example shown inFIG.3, IMD10may include a leadless device having a housing15and an insulative cover76. Electrodes16may be formed or placed on an outer surface of cover76. Communication system26, circuitries50-60and/or sensor(s)62, described above with respect toFIG.2, may be formed or placed on an inner surface of cover76, or otherwise within housing15. Sensor(s)62may include one or more temperature sensor(s)63located within housing15. In some examples, insulative cover76may be positioned over housing15, such that housing15and insulative cover76enclose communication system26, sensor(s)62, and/or circuitries50-60, and protect them from fluids.

One or more of communication system26, sensor(s)62, and/or circuitries50-60may be formed on the inner side of insulative cover76, such as by using flip-chip technology. Insulative cover76may be flipped onto a housing15. When flipped and placed onto housing15, the components of IMD10formed on the inner side of insulative cover76may be positioned in a gap78defined by housing15. Power source91of IMD10may be housed within housing15. Electrodes16may be electrically connected to switching circuitry58through one or more vias (not shown) formed through insulative cover76. Insulative cover76may be formed of sapphire (i.e., corundum), glass, parylene, and/or any other suitable insulating material. Housing15may be formed from titanium or any other suitable material (e.g., a biocompatible material). Electrodes16may be formed from any of stainless steel, titanium, platinum, iridium, or alloys thereof. In addition, electrodes16may be coated with a material such as titanium nitride or fractal titanium nitride, although other suitable materials and coatings for such electrodes may be used.

FIG.4is a block diagram illustrating an example configuration of components of external device12. In the example ofFIG.4, external device12includes processing circuitry80, communication circuitry82, storage device84, and user interface86.

Processing circuitry80may include one or more processors that are configured to implement functionality and/or process instructions for execution within external device12. For example, processing circuitry80may be capable of processing instructions stored in storage device84. Processing circuitry80may include, for example, microprocessors, DSPs, ASICs, FPGAs, or equivalent discrete or integrated logic circuitry, or a combination of any of the foregoing devices or circuitry. Accordingly, processing circuitry80may include any suitable structure, whether in hardware, software, firmware, or any combination thereof, to perform the functions ascribed herein to processing circuitry80.

Communication circuitry82may include any suitable hardware, firmware, software or any combination thereof for communicating with another device, such as IMD10. Under the control of processing circuitry80, communication circuitry82may receive downlink telemetry from, as well as send uplink telemetry to, IMD10, or another device. Communication circuitry82may be configured to transmit or receive signals via inductive coupling, electromagnetic coupling, Near Field Communication (NFC), RF communication, Bluetooth®, WI-FI™, or other proprietary or non-proprietary wireless communication schemes. Communication circuitry82may also be configured to communicate with devices other than IMD10via any of a variety of forms of wired and/or wireless communication and/or network protocols.

Storage device84may be configured to store information within external device12during operation. Storage device84may include a computer-readable storage medium or computer-readable storage device. In some examples, storage device84includes one or more of a short-term memory or a long-term memory. Storage device84may include, for example, RAM, DRAM, SRAM, magnetic discs, optical discs, flash memories, or forms of EPROM or EEPROM. In some examples, storage device84is used to store data indicative of instructions for execution by processing circuitry80. Storage device84may be used by software or applications running on external device12to temporarily store information during program execution. Storage device84may also store historical temperature data, current temperature data, etc.

External device12can additionally or alternatively include a peripheral pointing device, such as a mouse, via which the user may interact with the user interface. In some examples, a display of external device12may include a touch screen display, and a user may interact with external device12via the display. It should be noted that the user may also interact with external device12remotely via a networked computing device.

Data exchanged between external device12and IMD10may include operational parameters (e.g., such as a communication rate). External device12may transmit data including computer readable instructions which, when implemented by IMD10, may control IMD10to change one or more operational parameters and/or export collected data. For example, processing circuitry80may transmit an instruction to IMD10which requests IMD10to export collected data (e.g., diagnostic data) to external device12. In turn, external device12may receive the collected data from IMD10and store the collected data in storage device84.

A user, such as a clinician or patient4, may interact with external device12through user interface86. User interface86includes a display (not shown), such as a liquid crystal display (LCD) or a light emitting diode (LED) display or other type of screen, with which processing circuitry80may present information related to IMD10, e.g., cardiac EGMs. In addition, user interface86may include an input mechanism to receive input from the user. The input mechanisms may include, for example, any one or more of buttons, a keypad (e.g., an alphanumeric keypad), a peripheral pointing device, a touch screen, or another input mechanism that allows the user to navigate through user interfaces presented by processing circuitry80of external device12and provide input. In other examples, user interface86also includes audio circuitry for providing audible notifications, instructions or other sounds to the user, receiving voice commands from the user, or both.

Power source108delivers operating power to the components of external device12. Power source108may include a battery and a power generation circuit to produce the operating power. In some embodiments, the battery may be rechargeable to allow extended operation. Recharging may be accomplished by electrically coupling power source108to a cradle or plug that is connected to an alternating current (AC) outlet. In addition or alternatively, recharging may be accomplished through proximal inductive interaction between an external charger and an inductive charging coil within external device12. In other embodiments, traditional batteries (e.g., nickel cadmium or lithium ion batteries) may be used. In addition, external device12may be directly coupled to an alternating current outlet to power external device12. Power source108may include circuitry to monitor power remaining within a battery. In this manner, user interface86may provide a current battery level indicator or low battery level indicator when the battery needs to be replaced or recharged. In some cases, power source108may be capable of estimating the remaining time of operation using the current battery.

FIG.5is a block diagram illustrating an example system that includes an access point90, a network92, external computing devices, such as a server94, and one or more other computing devices100A-100N (collectively, “computing devices100”), which may be coupled to IMD10and external device12via network92, in accordance with one or more techniques described herein. In this example, IMD10may use communication system26to communicate with external device12via a first wireless connection, and to communicate with an access point90via a second wireless connection. In the example ofFIG.5, access point90, external device12, server94, and computing devices100are interconnected and may communicate with each other through network92. Network92may comprise a local area network, wide area network, or global network, such as the Internet. The system ofFIG.5may be implemented, in some aspects, with general network technology and functionality similar to that provided by the Medtronic CareLink® Network.

Access point90may include a device that connects to network92via any of a variety of connections, such as telephone dial-up, digital subscriber line (DSL), or cable modem connections. In other examples, access point90may be coupled to network92through different forms of connections, including wired or wireless connections. In some examples, access point90may be a user device, such as a tablet or smartphone, that may be co-located with the patient. IMD10may be configured to transmit data, such as temperature values, heart rate values, impedance values, and/or cardiac electrograms (EGMs), to access point90. Access point90may then communicate the retrieved data to server94via network92.

In some cases, server94may be configured to provide a secure storage site for data that has been collected from IMD10and/or external device12. In some cases, server94may assemble data in web pages or other documents for viewing by trained professionals, such as clinicians, via computing devices100. One or more aspects of the illustrated system ofFIG.5may be implemented with general network technology and functionality, which may be similar to that provided by the Medtronic CareLink® Network.

In some examples, one or more of computing devices100may be a tablet or other smart device located with a clinician, by which the clinician may program, receive data from, and/or interrogate IMD10. For example, the clinician may access data collected by IMD10through a computing device100, such as when patient4is in between clinician visits, to check on a status of a medical condition. In some examples, the clinician may enter instructions for a medical intervention for patient4into an application executed by computing device100, such as based on patient data known to the clinician. Device100then may transmit the instructions for medical intervention to another of computing devices100located with patient4or a caregiver of patient4. For example, such instructions for medical intervention may include an instruction to change a drug dosage, timing, or selection, to schedule a visit with the clinician, or to seek medical attention. In further examples, a computing device100may generate an alert to patient4based on a status of a medical condition of patient4, which may enable patient4proactively to seek medical attention prior to receiving instructions for a medical intervention. In this manner, patient4may be empowered to take action, as needed, to address his or her medical status, which may help improve clinical outcomes for patient4.

In the example illustrated byFIG.5, server94includes a storage device96, e.g., to store data retrieved from IMD10, and processing circuitry98. Although not illustrated inFIG.5computing devices100may similarly include a storage device and processing circuitry. Processing circuitry98may include one or more processors that are configured to implement functionality and/or process instructions for execution within server94. For example, processing circuitry98may be capable of processing instructions stored in storage device96(e.g., stored in memory). Processing circuitry98may include, for example, microprocessors, DSPs, ASICs, FPGAs, or equivalent discrete or integrated logic circuitry, or a combination of any of the foregoing devices or circuitry. Accordingly, processing circuitry98may include any suitable structure, whether in hardware, software, firmware, or any combination thereof, to perform the functions ascribed herein to processing circuitry98.

Storage device96may include a computer-readable storage medium or computer-readable storage device. In some examples, storage device96includes one or more of a short-term memory or a long-term memory. Storage device96may include, for example, RAM, DRAM, SRAM, magnetic discs, optical discs, flash memories, or forms of EPROM or EEPROM. In some examples, storage device96is used to store data indicative of instructions for execution by processing circuitry98.

FIG.6is a flow diagram illustrating an example operation for switching an IMD from a first mode to a second mode based on signals from one or more temperature sensor(s)63and biosensor(s)53, in accordance with one or more techniques of this disclosure.

In some examples, processing circuitry, e.g., processing circuitry50of IMD10, may receive a first signal indicating one or more temperature values from temperature sensor(s)63(602). For example, processing circuitry50may obtain raw temperature data from one or more of temperature sensor(s)63. Temperature sensor(s)63may detect temperature in and/or around IMD10.

In some examples, processing circuitry50may obtain temperature values from temperature sensor(s)63over time. In some examples, processing circuitry50may obtain temperature values from temperature sensor(s)63every second, every minute, hourly, daily, etc. or may obtain temperature values from temperature sensor(s)63in an aperiodic fashion. For example, processing circuitry50may control temperature sensor(s)63to perform random temperature measurements at random times during a set time period (e.g., randomly throughout each day).

Processing circuitry50may receive a first signal from temperature sensor(s)63, e.g., via sensing circuitry52, and may determine a temperature value of IMD10based on the first signal. In some examples, processing circuitry50may determine temperature values of IMD10over time as a series of discrete temperature values and determine a temperature value based on the series of discrete temperature values. In some examples, processing circuitry50may determine the temperature values at a sampling rate during each of a plurality of sampling periods during a predefined time period. For example, processing circuitry50may determine temperature values at a sampling rate of twice every hour over the course of a 24-hour time period. In another example, processing circuitry50may determine temperature values at a sampling rate of once every hour during specific times of the day, such as between 8:00 am and 5:00 pm. In some examples, processing circuitry50may determine temperature values at a sampling rate of once per minute.

In some examples, processing circuitry50of IMD10, may make a first preliminary determination of whether IMD10is implanted based on the obtained temperature (604). For example, processing circuitry50may make the first preliminary determination based on whether or not the temperature value satisfies a temperature criterion64as stored in storage device60. If the first preliminary determination is that IMD10has not been implanted (“NO” branch of604), processing circuitry50may repeat action (602). However, if the first preliminary determination is that IMD10has been implanted (“YES” branch of604), processing circuitry50may obtain a second signal from biosensor(s)53(606).

In some examples, biosensor(s)53may include an impedance sensor. Biosensor(s)53may send a second signal indicating an impedance value to processing circuitry50and processing circuitry50may identify an impedance value based on the second signal. For example, biosensor(s)53may include sample and hold circuitry to sample the voltage across the resistance. Using this voltage, processing circuitry50may calculate the impedance. Processing circuitry50and biosensor(s)53may sample the voltage with a sampling rate that is sufficiently high enough to reliably identify the impedance signal. For example, processing circuitry50and biosensor(s)53may sample the voltage rate with a sampling rate around 1000 hertz.

In some examples, biosensor(s)53may include an ECG sensor. Biosensor(s)53may send a second signal indicating heart activity to processing circuitry50and processing circuitry50may identify a heart rate value based on the second signal. For example, biosensor(s)53may include an ECG sensor configured to detect electrical signals produced by heart activity via electrodes16. Using the electrical signals, processing circuitry50may determine a heart rate of patient4.

In some examples, processing circuitry, e.g., processing circuitry50of IMD10, may make a second preliminary determination of whether IMD10is implanted based on the impedance value or the heart rate value (608). For example, processing circuitry50may make the second preliminary determination based on whether or not the impedance value satisfies impedance criterion66as stored in storage device60. As another example, processing circuitry50may make the second preliminary determination based on whether or not the heart rate value satisfies heart rate criterion68as stored in storage device60. If the second preliminary determination is that IMD10has been implanted (“NO” branch of608), processing circuitry50may repeat actions (602) through (606), as needed. If the second preliminary determination is that IMD10has been implanted (“YES” branch of608), processing circuitry50may determine that IMD10has been implanted based on both the first preliminary determination and the second preliminary determination being that IMD10has been implanted (610).

Use of temperature signals alone to determine whether an IMD has been implanted may be prone to false triggering. For instance, it may be difficult to distinguish based on temperature signals whether an IMD has been implanted in a patient versus whether the IMD has been in a warm environment. The consequences of false triggering may result in wasteful drain on the resources and may shorten the lifespan of the IMD.

The techniques of this disclosure may improve the detection capabilities of IMDs. Using both the temperature signal and the second signal, e.g., the impedance signal or the heart rate signal, to determine whether IMD10has been implanted may be more robust than using only the temperature signal or the second signal alone to determine whether IMD10has been implanted. This is because processor circuitry50may be able to use the second preliminary determination based on the second signal as a check on the first preliminary determination based on the temperature signal. Additionally, examples in which impedance sensing or heart activity monitoring is activated in response to sensed temperature satisfying a temperature criterion may avoid unnecessary expenditure of energy associated with impedance or heart rate measurements.

In response to the determination being that IMD10is implanted, processing circuitry50may then cause IMD10to switch from a first mode to a second mode (612). For example, IMD10may be switched from a dormant mode, e.g., a mode does not include communication with an external computing device such as external device12or access point90, to an activated mode, e.g., a mode include communication with an external computing device, upon a determination that IMD10is implanted in the body of patient4. Processing circuitry50may cause IMD10to switch operation mode in accordance with any of the examples provided elsewhere in this disclosure. Accordingly, the techniques of this disclosure may preserve power source91of IMD10and may reduce unintended communication connection process between IMD10and an external device, such as external device12.

FIG.7is a flow diagram illustrating an example operation for making a first preliminary determination that an IMD is implanted based a first signal from a temperature sensor, in accordance with one or more techniques of this disclosure.

In some examples, processing circuitry50may receive a first signal indicating one or more temperature values from temperature sensor(s)63and determine a temperature based on the first signal (702). For example, processing circuitry50may apply a low-pass filter to smooth the one or more temperature values and determine an average of the one or more smoothened temperature values.

In some examples, processing circuitry50may smooth the temperature values sensed over time to decrease an amount of noise in sensed temperature values caused by various factors, including environmental factors. For example, processing circuitry50may apply a low-pass filter to a plurality of temperature values using a digital filter or in some instances, an analog filter. In one example, processing circuitry50may apply a digital filter that increases signal-to-noise ratio (SNR) to create a smoothened temperature signal by filtering out high frequency noise or other high frequency variations from temperature values determined over time. In another example, processing circuitry50may smoothen the temperature values using a low pass differentiator filter that performs smoothing based on predefined coefficients and/or smoothing differentiator filter functions to remove high frequency variations in temperature values determined over time. In some examples, processing circuitry50may apply a low-pass filter that passes low-frequency temperature variations while impeding high-frequency temperature variations. The low-pass filter may have a predefined cutoff frequency that attenuates temperature variations exceeding that of the cutoff frequency. Processing circuitry50may then determine a temperature value by calculating an average of the smoothened temperature values.

In some examples, processing circuitry50may determine whether or not the temperature satisfies temperature criterion64as stored in storage device60(704). Processing circuitry50may make this determination in any of various ways. In some examples, processing circuitry50may determine that the temperature satisfies temperature criterion64based on the temperature meeting a predefined threshold value (e.g., 37 degree Celsius).

In response to determining that the temperature satisfies temperature criterion64as stored in storage device60(“YES” branch of704), processing circuitry50may make a first preliminary determination that IMD10is implanted in the body of patient4(706). However, if processing circuitry50determines that the temperature has not satisfied temperature criterion64as stored in storage device60(“NO” branch of704), processing circuitry50continue to obtain sample values from temperature sensor(s)63and determine whether IMD10has been implanted.

FIG.8Ais a flow diagram illustrating an example operation for making a second preliminary determination that an IMD is implanted based a second signal from a biosensor, in accordance with one or more techniques of this disclosure.

In some examples, processing circuitry50may receive a second signal indicating one or more impedance values from biosensor(s)53and determine an impedance value based on the second signal (802). For example, processing circuitry50may cause biosensor(s)53to send an electrical signal to fluid and/or tissue in an electrical path between a first electrode16A and a second electrode16B of IMD10. Processing circuitry50may then identify an impedance of the signal between these two electrodes.

In some examples, processing circuitry50may determine whether or not the impedance satisfies impedance criterion66as stored in storage device60(804). Processing circuitry50may make this determination in any of various ways. In some examples, processing circuitry50may determine that the impedance satisfies impedance criterion66based on the impedance meeting a predefined range. For example, processing circuitry50may determine whether or not the impedance that is below an impedance threshold as stored in storage device60. The impedance threshold may include a static value where a momentary spike is sufficient processing circuitry50to determine that IMD10is implanted in the body of patient4. Alternatively, the impedance threshold may include an average impedance magnitude over a period of time (e.g., over one or two seconds).

In response to determining that the impedance satisfies impedance criterion66as stored in storage device60(“YES” branch of804), processing circuitry50may make a second preliminary determination that IMD10is implanted in the body of patient4(806). However, if processing circuitry50determines that the impedance has not satisfied impedance criterion66as stored in storage device60(“NO” branch of804), processing circuitry50continue to obtain sample values from sensor(s)62and determine whether IMD10has been implanted.

FIG.8Bis a flow diagram illustrating another example operation for making a second preliminary determination that an IMD is implanted based a second signal from a biosensor, in accordance with one or more techniques of this disclosure.

In some examples, processing circuitry50may receive a second signal indicating heart activity from biosensor(s)53and determine a heart rate based on the second signal (808). For example, processing circuitry50may receive signal indicating heart activity from biosensor(s)53and may process the signal to obtain a heart rate of patient4.

In some examples, processing circuitry50may determine whether or not the heart rate satisfies heart rate criterion68as stored in storage device60(810). Processing circuitry50may make this determination in any of various ways. In some examples, processing circuitry50may determine that the heart rate satisfies heart rate criterion68based on the heart rate is within a heart rate range. In one example, the heart rate range is between 30 beats per minutes (bpm) to 200 bpm.

In response to determining that the heart rate satisfies heart rate criterion68as stored in storage device60(“YES” branch of810), processing circuitry50may make a second preliminary determination that IMD10is implanted in the body of patient4(812). However, if processing circuitry50determines that the heart rate has not satisfied heart rate criterion68as stored in storage device60(“NO” branch of810), processing circuitry50continue to obtain sample values from sensor(s)62and determine whether IMD10has been implanted.

FIG.9is a flow diagram illustrating an example operation for switching an IMD from a first mode to a second mode based on a wakeup signal, in accordance with one or more techniques of this disclosure. In some examples, processing circuitry50may activate communication system26in response to a first preliminary determination being that IMD10is implanted (902). An external device, such as external device12, may generate a wakeup signal and transmit the wakeup signal to IMD10via TCC. In response to communication system26receiving the wakeup signal from the external device (“YES” branch of904), e.g., via electrodes16processing circuitry50may switch IMD10from a first mode to a second mode (906). However, if processing circuitry50does not receive the wakeup signal (“NO” branch of904), processing circuitry50may inactivate communication system26after a predefined time. In some cases, activation of communication system26in response to a first preliminary determination being that IMD10is implanted may be in addition to activation of biosensor(s)53for impedance or heart rate measurement as described herein, e.g., with respect toFIGS.6and8.

FIG.10is a flow diagram illustrating an example operation for an IMD broadcasting a message using an advertising rate in a second mode, in accordance with one or more techniques of this disclosure.

In some examples, processing circuitry50is configured to switch IMD10from a first mode to a second mode (1002). In some examples, IMD10may be switched from a dormant mode (e.g., a first mode does not include communication with an external computing device) to an activated mode (e.g., a second mode include communication with an external computing device). For instance, processing circuitry50may be configured to activate communication system26upon IMD10being switched to the activated mode (1004). In some examples, IMD10may be switched from a low-power mode to a high-power mode (e.g., from a first mode includes a relatively low power consumption to a second mode includes a relatively high power consumption).

In some examples, processing circuitry50is configured to activate communication system26to transmit a message to an external device (1006), such as external device12. IMD10may transmits the message according to a protocol stored in storage device60. In some examples, the protocol includes Bluetooth® protocol such as a BTLE protocol having a low-power mode and a high-power mode. For example, in the low-power mode, IMD10may transmit a message including a set of advertisements at a first advertisement rate. Additionally, in the high-power mode, IMD10may transmit a message including a set of advertisements at a second advertisement rate, where the second advertisement rate is greater than the first advertisement rate. In other examples, IMD10does not transmit any advertisements in dormant mode and IMD10initiates the transmission of advertisements after switching to activated mode.

Data exchanged between external device12and IMD10may include any data stored in storage device60. External device12may transmit data including computer readable instructions which, when implemented by IMD10, may control IMD10to export collected data. For example, processing circuitry50may transmit an instruction to IMD10which requests IMD10to export collected data to external device12. In turn, external device12may receive the collected data from IMD10and store the collected data in storage device84.

FIG.11is a flow diagram illustrating another example operation for switching an IMD from a first mode to a second mode based on signals from temperature sensor and biosensor, in accordance with one or more techniques of this disclosure.

In some examples, in order to preserve power for testing after explant of an IMD, the IMD may stay locked until certain sensor conditions are met. As illustrated inFIG.11, processing circuitry, e.g., processing circuitry50of IMD10, may receive a signal indicating a temperature from temperature sensor(s)63(1102). Processing circuitry50of IMD10may then determine whether a temperature criterion64is satisfied based on the received signal (1104). In some examples, processing circuitry50may determine that temperature criterion64is satisfied when the temperature is below a certain threshold value (e.g., 37 degree Celsius).

In response to determining that the temperature has not satisfied temperature criterion64as stored in storage device60(“NO” branch of1104), processing circuitry50continue to obtain sample values from temperature sensor(s)63and determine whether temperature criterion64has been satisfied. However, if the temperature satisfies temperature criterion64as stored in storage device60(“YES” branch of1104), processing circuitry50may activate communication system26. For example, processing circuitry50may activate communication system26to enable IMD10to receive unsecured communications from external device12for a predefined time window (1106).

During that time window, processing circuitry50may receive a command from external device12and may verify the command by comparing the received command with a command stored in storage device60(1108). For example, if the received command matches an unlock command stored in storage device60, processing circuitry50may switch IMD10from a first mode to a second mode. In some examples, IMD10may be switched from a locked mode (e.g., a first mode does not permit unsecured communication with an external computing device) to an unlocked mode (e.g., a second mode permit unsecured communication with an external computing device).

The techniques described in this disclosure may be implemented, at least in part, in hardware, software, firmware, or any combination thereof. For example, various aspects of the techniques may be implemented within one or more microprocessors, DSPs, ASICs, FPGAs, or any other equivalent integrated or discrete logic QRS circuitry, as well as any combinations of such components, embodied in external devices, such as physician or patient programmers, stimulators, or other devices. The terms “processor” and “processing circuitry” may generally refer to any of the foregoing logic circuitry, alone or in combination with other logic circuitry, or any other equivalent circuitry, and alone or in combination with other digital or analog circuitry.

For aspects implemented in software, at least some of the functionality ascribed to the systems and devices described in this disclosure may be embodied as instructions on a computer-readable storage medium such as RAM, ROM, NVRAM, DRAM, SRAM, Flash memory, magnetic discs, optical discs, flash memories, or forms of EPROM or EEPROM. The instructions may be executed to support one or more aspects of the functionality described in this disclosure.

In addition, in some aspects, the functionality described herein may be provided within dedicated hardware and/or software modules. Depiction of different features as modules or units is intended to highlight different functional aspects and does not necessarily imply that such modules or units must be realized by separate hardware or software components. Rather, functionality associated with one or more modules or units may be performed by separate hardware or software components, or integrated within common or separate hardware or software components. Also, the techniques could be fully implemented in one or more circuits or logic elements. The techniques of this disclosure may be implemented in a wide variety of devices or apparatuses, including an IMD, an external programmer, a combination of an IMD and external programmer, an integrated circuit (IC) or a set of ICs, and/or discrete electrical circuitry, residing in an IMD and/or external programmer.

Furthermore, although described primarily with reference to examples that provide an infection status to indicate a device pocket infection in response to detecting temperature changes in the device pocket, other examples may additionally or alternatively automatically modify a therapy in response to detecting the infection status in the patient. The therapy may be, as examples, a substance delivered by an implantable pump, a delivery of antibiotics, etc. These and other examples are within the scope of the following claims.