Method for monitoring side-lying respiration

Abstract

A mobile medical device includes a multi-axis gesture sensor and processing circuitry. The multi-axis posture sensor is configured to provide an electrical posture sensor output representative of alignment of the respective first, second, and third non-parallel axes of the mobile medical device with the earth's gravitational field. The processing circuit is configured to use the gesture sensor output to determine that the subject is prevented from lying on its left side, and to calculate a metric that predicts one or both of seated and side-lying breaths in response to determining that the subject is prevented from lying on its left side.

Description

[0001] Priority requirements

[0002] This application claims priority to U.S. Provisional Application No. 63 / 528,187, filed July 21, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This document generally relates to cardiac rhythm management systems, and in particular, but not in a limited manner, to methods, systems, and devices for automatically monitoring a patient's lateral respiration (trepopnea) using mobile medical devices. Background Technology

[0004] Ambulatory medical devices (AMDs) include implantable medical devices (IMDs), insertable cardiac monitors (ICMs), and wearable cardiac monitors. Some examples of IMDs include cardiac function management (CFM) devices, such as implantable pacemakers, implantable cardioverter defibrillators (ICDs), cardiac resynchronization therapy devices (CRTs), and devices that include combinations of these functions. These devices can be used to treat patients or subjects using electrotherapy or other therapies, or to assist physicians or caregivers in patient diagnosis through internal monitoring of a patient's condition. Devices may include one or more electrodes communicating with one or more sensing amplifiers to monitor cardiac electrical activity within the patient's body, and typically include one or more sensors to monitor one or more other internal patient parameters. Other examples of IMDs include implantable diagnostic devices, implantable drug delivery systems, or implantable devices with neurostimulation capabilities.

[0005] Wearable cardiac monitors may include surface electrodes. These surface electrodes are positioned to provide monitoring of surface electrocardiograms (ECG) and delivery of one or more cardioverter-defibrillator shocks.

[0006] Some AMD devices include one or more sensors to monitor different physiological aspects of a patient. Sensing patient posture can provide information related to the patient's condition or disease. For example, as their condition worsens, a patient with congestive heart failure (CHF) may tend to sleep in a higher position. Monitoring a patient's orientation can provide useful information for caregivers to diagnose the patient's condition. Summary of the Invention

[0007] Device-based monitoring of heart failure patients, which avoids them lying on their left side, can provide information about their condition. This information and analysis can be performed outside the clinical setting.

[0008] Example 1 includes a subject (such as a method of operating a mobile medical device or an AMD) comprising using the AMD's multi-axis posture sensor to determine that the subject avoids lying on their left side, and in response to determining that the subject avoids lying on their left side, calculating a metric of one or both of predicted sitting-up breathing and lateral breathing. The posture sensor is configured to provide an electrical posture sensor output representing the alignment of the AMD's respective first, second, and third non-parallel axes with the Earth's gravitational field.

[0009] In Example 2, the subject matter described in Example 1 may optionally include trend analysis by the AMD on the amount of time the subject spends lying on the left side, and using the trend to generate an indication of the subject's heart failure state.

[0010] In Example 3, the subject matter described in one or both of Examples 1 and 2 may optionally include using the output of a calibrated posture sensor to determine the subject's elevation angle, using the output of a calibrated posture sensor to determine the subject's lateral angle, and performing trend analysis on the amount of time the determined elevation and lateral angles indicate that the subject is on its left side.

[0011] In Example 4, the subject matter described in Example 3 may optionally include generating one or both of the subject’s sitting-up breathing and lying-down breathing states using the determined elevation angle and the determined lateral angle.

[0012] In Example 5, the subject matter described according to one or any combination of Examples 1-4 may optionally include determining the direction of the current gravity vector relative to the axis of the posture sensor, calculating the angular change between the current gravity vector and the direction of a previously measured gravity vector relative to the axis of the posture sensor, calculating multiple angular changes, and using the determined angular changes to determine the subject on its left side.

[0013] In Example 6, the subject matter described in Example 5 may optionally include using the dot product of the current gravity vector and the previously measured gravity vector to determine the angle change.

[0014] In Example 7, the subject may optionally be determined to be on the left side using a predetermined percentage of the largest angle change among the plurality of angle changes, based on one or both of the topics described in Examples 5 and 6.

[0015] In Example 8, the subject matter described according to one or any combination of Examples 1-7 may optionally include calibrating the output of the multi-axis posture sensor to the orientation of the AMD relative to the orientation of the subject, and using the calibrated output of the multi-axis posture sensor to determine that the subject is stationary and lying on his left side.

[0016] Example 9 includes a subject (such as AMD), or may optionally be combined with one or any combination of Examples 1-8 to include a subject comprising a multi-axis posture sensor configured to provide an electrical posture sensor output representing the alignment of the respective first, second, and third non-parallel axes of the AMD with the Earth's gravitational field; and processing circuitry communicatively coupled to the multi-axis posture sensor. The processing circuitry is configured to use the posture sensor output to determine that the subject avoids lying on their left side, and in response to determining that the subject avoids lying on their left side, to calculate a measure of one or both of predicted sitting-up breathing and lateral recumbent breathing.

[0017] In Example 10, the subject matter according to Example 9 may optionally include processing circuitry configured to: detect that the subject is stationary using the output of a calibrated posture sensor, determine that the subject avoids lying on its left side using the output of the calibrated posture sensor, and, in response to determining that the subject avoids lying on its left side, calculate a metric of one or both of orthopneic breathing and lateral breathing.

[0018] In Example 11, the subject matter according to one or both of Examples 10 and 11 may optionally include processing circuitry configured to calculate the subject's elevation angle using the posture sensor output, calculate the subject's lateral angle using the posture sensor output, and calculate the subject's elevation angle within a predetermined range of supine elevation angles, with the lateral angle indicating the amount of time the subject is on their left side as the metric.

[0019] In Example 12, the subject matter according to Example 11 may optionally include processing circuitry configured to generate one or both of the subject’s sitting-up breathing and lying-down breathing states using a determined elevation angle and a determined lateral angle.

[0020] In Example 13, the subject matter according to one or any combination of Examples 9-12 may optionally include processing circuitry configured to: calculate the direction of a first gravity vector relative to the axis of the posture sensor; calculate the direction of a second gravity vector relative to the axis of the posture sensor; calculate the angular change between the second gravity vector and the first gravity vector; and calculate the continuous angular change between the second gravity vector and the first gravity vector, using the calculated continuous angular change to determine that the subject should avoid lying on his left side.

[0021] In Example 14, the subject matter according to Example 13 may optionally include processing circuitry configured to calculate the dot product of the second gravity vector and the first gravity vector to calculate the angular change between the second gravity vector and the first gravity vector.

[0022] In Example 15, the subject matter according to one or both of Examples 13 and 14 may optionally include processing circuitry configured to calculate a plurality of gravity vectors and calculate a plurality of angular changes between the gravity vectors; identify a predetermined percentile of the calculated angular changes having the highest value; calculate an average of the calculated angular changes; and, based on the average of the calculated angular changes, determine that the subject should avoid lying on his left side.

[0023] In Example 16, the subject matter described according to one or any combination of Examples 9-15 may optionally include a posture sensor that is a multi-axis accelerometer, and processing circuitry configured to calibrate the output of the multi-axis accelerometer to the orientation of the AMD relative to the subject, and to determine, using the calibrated output of the multi-axis accelerometer, that the subject is stationary and lying on his left side.

[0024] In Example 17, the subject matter according to one or any combination of Examples 9-16 may optionally include communication circuitry operatively coupled to the processing circuitry and configured to transmit information to a separate device; and processing circuitry configured to use the amount of time the subject has been lying on his left side to generate an indication of the subject's heart failure state, and to send the indication to the separate device.

[0025] Example 18 includes a subject (such as a programming device for an AMD), or may optionally be combined with one or any combination of Examples 1-17 to include a subject comprising communication circuitry configured to wirelessly communicate information with the AMD, a user interface, and programming control circuitry operatively coupled to the communication circuitry and the user interface. The programming control circuitry is configured to receive orientation information of a subject from the AMD, use the orientation information to calculate a metric instructing the subject to avoid lying on their left side, and generate an indication of the subject's heart failure state based on a comparison of the metric with a lateral recumbency detection threshold.

[0026] In Example 19, the subject matter according to Example 18 may optionally include a programmable control circuit configured to receive a trend of the subject’s lateral angle information from the AMD and use the trend of the lateral angle information to generate the indication of a heart failure state.

[0027] In Example 20, the subject matter according to Example 18 may optionally include a programmable control circuit configured to receive a trend of orientation angle change information from the AMD, wherein the angle change information includes an angle change calculated between consecutive gravity vectors measured by the AMD; and use the trend of the angle change information to generate the indication of a heart failure state.

[0028] These non-limiting examples can be combined in any arrangement or combination. This summary is intended to provide an overview of the subject matter of this patent application. It is not intended to provide a unique or exhaustive interpretation of this disclosure. The detailed description is included to provide further information about this patent application. Other aspects of this disclosure will be apparent to those skilled in the art upon reading and understanding the following detailed description and viewing the accompanying drawings, which form a part of it, and each of the drawings should not be construed as limiting. Attached Figure Description

[0029] In accompanying drawings that are not necessarily drawn to scale, the same numbers may describe similar parts in different views. The same numbers with different letter suffixes may represent different instances of similar parts. The accompanying drawings illustrate various embodiments discussed in this document by way of example and not by way of limitation.

[0030] Figure 1 An example Cardiac Rhythm Management (CRM) system is shown.

[0031] Figure 2 An example of a mobile medical device (AMD) and its operating environment is shown.

[0032] Figure 3 This is a block diagram of AMD's electronic circuitry.

[0033] Figure 4 This is a block diagram of an external device that communicates with AMD.

[0034] Figures 5A-5C An example of patient orientation is shown.

[0035] Figure 6 This is a flowchart of the method for operating a CRM system.

[0036] Figure 7 An example of the trend in the lateral angle information of the subjects is shown.

[0037] Figure 8 An example of a coordinate system for the patient's body is shown.

[0038] Figure 9 An example of AMD's device coordinate system is shown.

[0039] Figure 10 This illustrates another example of a deviation between the device coordinate system and the body coordinates of the patient using the device.

[0040] Figures 11A-11B Examples are shown of trends in side angle measurements taken with a calibrated multi-axis accelerometer and trends in maximum gravitational vector angle change (Max GVAC) measured with an uncalibrated multi-axis accelerometer.

[0041] Figure 12A and Figure 12B This is a diagram showing the patient's upward angle.

[0042] Figure 13 A graph showing the average of the maximum GVAC values ​​for patients is presented. Detailed Implementation

[0043] Mobile medical devices (AMDs) can be used to provide cardiac pacing therapy to patients or other subjects. An AMD may include or be configured to receive physiological information from one or more sensors located within, on, or near the patient's body. Among other things, the patient's physiological information may include respiratory information (e.g., respiratory rate, respiratory volume (tidal volume), acceleration information (e.g., cardiac vibration information, heart sound information, endocardial acceleration information, activity information, posture information, etc.); impedance information; electrocardiographic information; pressure information; plethysmography information; chemical information; temperature information; or other physiological information of the patient.

[0044] Posture sensing in medical devices can improve patient monitoring. Some examples of posture sensors include multi-axis accelerometers and tilt switches. With posture sensors, medical devices can detect whether a patient is upright, supine, prone, on their left or right side, or tilted. For patients with heart failure, posture sensing allows monitoring orthopneic breathing; situations where a patient can only breathe easily in an upright or near-upright posture (e.g., standing or sitting with the trunk upright). Posture sensing allows monitoring lateral recumbent breathing; situations where a patient avoids lying on their left side. Patients with congestive heart failure may avoid sleeping on their left side. Monitoring a patient's lateral recumbent breathing can provide information about the patient's heart failure status.

[0045] Figure 1 A portion of an example of a CRM system 100 and a portion of an environment in which the CRM system 100 can be used are shown. The CRM system 100 may include an implantable AMD 102, an external system 104, and communication links such as a telemetry link 106. The AMD 102 may include an electronic unit coupled to the heart 110 of a subject 112 via a cardiac lead 108 or an additional lead. Examples of the AMD 102 may include, but are not limited to, one or more pacemakers / defibrillators, cardiac resynchronization devices, cardiac remodeling control devices, and cardiac monitors. In the example, the AMD 102 may be configured to monitor the health status of the heart 110 and identify one or more abnormalities associated with the heart 110. The AMD 102 may take necessary actions, such as stimulating one or more portions of the heart 110 via the lead 108, to treat one or more abnormalities.

[0046] In the example, external system 104 may include external device 107 configured to communicate bidirectionally with AMD 102, such as via wireless telemetry link 106. For example, external device 107 may include a programmer for programming AMD 102 to deliver one or more therapies to heart 110. In the example, external device 107 may program AMD 102 to detect the presence of conduction block in heart 110 and prevent asynchronous contraction of heart 110 by delivering cardiac resynchronization therapy (CRT) to heart 110.

[0047] In the example, external device 107 can be configured to send data to AMD 102 via telemetry link 106. Examples of such data transmission may include programmed instructions for AMD 102 to acquire physiological data, perform at least one self-diagnostic test (such as for device operating status), or deliver at least one therapy or any other data. In the example, AMD 102 can be configured to send data to external device 107 via telemetry link 106. The transmitted data may include real-time physiological data acquired by or stored in AMD 102, therapy history data, operating status of AMD 102 (e.g., battery status or lead impedance), etc. Telemetry link 106 may include an inductive telemetry link or a radio frequency telemetry link.

[0048] In this example, external device 107 may be a component of a CRM system, which may include other devices such as a remote system 114 for remotely programming the AMD 102. In this example, remote system 114 may include a server 116 that can communicate with external device 107 via an electrical communication network 118 to access the AMD 102 to remotely monitor the health of the heart 110 or adjust parameters associated with one or more therapies.

[0049] Figure 2 A CRM system 100 is illustrated, comprising an AMD 102, which is implantable and electrically coupled to a heart 110 via one or more leads 108A, 108B, 108C, coupled to the AMD 102 through one or more lead ports in a connector 203. In the example, the AMD 102 may include an antenna (such as in connector 203) configured to communicate with external systems and one or more electronic circuits (e.g., evaluation circuitry) in a hermetically sealed enclosure (CAN) 201. The AMD 102 illustrates an exemplary mobile medical device (or medical device system) as described herein. System 100 also includes an AMD programmer or other external device 107 that communicates wirelessly with the AMD 102 using a telemetry link 106.

[0050] Cardiac leads 108A, 108B, and 108C include a proximal end coupled to AMD 102 and a distal end coupled to one or more portions of heart 110 by electrical contacts or "electrodes." The electrodes typically deliver cardioversion, defibrillation, pacing, or resynchronization therapy, or combinations thereof, to at least one chamber of heart 110. The electrodes may be electrically coupled to a sensing amplifier to sense electrocardiographic signals.

[0051] Heart 110 includes a right atrium 220A, a left atrium 220B, a right ventricle 222A, a left ventricle 222B, and a coronary sinus 224 extending from the right atrium 220A. Right atrial (RA) lead 108A includes electrodes (electrical contacts, such as ring electrodes 225 and tip electrodes 230) disposed in the right atrium 220A of heart 110 for sensing signals or delivering pacing therapy to atrium 100A, or both.

[0052] The right ventricular (RV) lead 108B includes one or more electrodes (such as a tip electrode 235 and a loop electrode 240) for sensing signals, delivering pacing therapy, or simultaneously sensing signals and delivering pacing therapy. Lead 108B may optionally also include additional electrodes, such as those for delivering atrial cardioversion, atrial defibrillation, ventricular cardioversion, ventricular defibrillation, or combinations thereof to the heart 110. Defibrillation electrodes typically have a larger surface area than pacing electrodes to handle the greater energy involved in defibrillation. Lead 108B may optionally provide resynchronization therapy to the heart 110. Resynchronization therapy is typically delivered to the ventricles to better synchronize the timing of depolarization between the ventricles.

[0053] Lead 108B may include an RV defibrillator coil electrode 275 located proximal to the tip electrode 235 and the loop electrode 240 for placement in the right ventricle; and a second defibrillator coil electrode 280 located proximal to the RV defibrillator coil 275, the tip electrode 235, and the loop electrode 240 for placement in the superior vena cava (SVC). In some examples, high-energy electrical shock therapy is delivered from the RV coil 275 to the second or SVC coil 280. In some examples, the SVC coil 280 is electrically linked to an electrode formed on CAN 201. This improves defibrillation by delivering current more uniformly from the RV coil 275 across the ventricular myocardium. In some examples, therapy is delivered only from the RV coil 275 to the electrode formed on CAN 201.

[0054] The AMD 102 may include a third cardiac lead 108C attached to the AMD 102 via a connector 203. The third cardiac lead 108C includes ring electrodes 260 and 265, which are positioned via coronary vein 216 in the coronary vein on the epicardium of the left ventricle (LV) 222B. The third cardiac lead 108C may include a ring electrode 285 located near the coronary sinus (CS) 224.

[0055] Please note that although the illustrations show a specific arrangement of leads and electrodes, this method and system will operate with a variety of configurations and electrodes. Other forms of electrodes include meshes and patches, which can be applied to certain parts of the heart 110 or implanted in other areas of the body to help “direct” the current generated by the AMD 102.

[0056] AMD can be configured with various electrode arrangements, including transvenous electrodes, endocardial electrodes and epicardial electrodes (i.e., intrathoracic electrodes), and / or subcutaneous electrodes, non-intrathoracic electrodes, including canisters, connectors and neutral electrodes, as well as subcutaneous arrays or leaded electrodes (i.e., non-intrathoracic electrodes).

[0057] Figure 3 This is a block diagram of the electronic circuitry of the implantable AMD 102. The AMD 102 can be coupled to multiple implantable electrodes, such as... Figure 2 The electrode arrangement is described in the example. The AMD 102 includes cardiac signal sensing circuitry 304, treatment circuitry 306, posture sensor 314, switching circuitry 310, communication circuitry 312, and control circuitry 308. When treatment circuitry 306 is operatively connected to the system's pacing electrodes, treatment circuitry 306 provides electrical pacing stimulation energy to the patient's heart. The pacing electrodes may include... Figure 2 Any pacing electrode, such as electrodes configured to be placed in or near the RA, RV, LV, His bundle or left bundle branch, and the CAN electrode.

[0058] The cardiac signal sensing circuit 304 includes one or more sensing amplifiers for sensing one or both of a voltage signal or a current signal at the sensing electrodes. The cardiac signal sensing circuit 304 can be used to sense a patient's electrocardiogram (ECG) information. Timing measures between different features (e.g., first cardiac features and second cardiac features) in the sensed electrical signals can be determined, for example, by the control circuit 308. In some examples, the timing measures may include the interval or measure between the first and second cardiac features of a patient's first cardiac interval (e.g., the duration of the cardiac cycle or interval, QRS width, etc.), or the time interval or measure between the first and second cardiac features of corresponding consecutive first and second cardiac intervals of the patient. In examples, the first and second cardiac features include equivalent detection features in consecutive first and second cardiac intervals, such as consecutive R waves (e.g., RR intervals, etc.) or one or more other features of the ECG signal. Far-field cardiac signals can be sensed using the electrodes of the CAN 201.

[0059] Switching circuit 310 electrically couples different combinations of electrodes to treatment circuit 306 and cardiac signal sensing circuit 304. Switching circuit 310 can configure any combination of electrodes as a pacing vector to deliver cardiac pacing stimulation energy, or configure any combination of electrodes as a sensing vector to sense cardiac signals.

[0060] Control circuitry 308 may include a digital signal processor, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a microprocessor, or other type of processor for interpreting or executing instructions in software or firmware. In some examples, control circuitry 308 may include a state machine or sequencer implemented in hardware circuitry. Control circuitry 308 may include any combination of hardware, firmware, or software. Control circuitry 308 includes one or more circuits to perform the functions described herein. Circuitry may include software, hardware, firmware, or any combination thereof. For example, the circuitry may include instructions in software executing on control circuitry 308. One or more circuits of control circuitry 308 may perform multiple functions. Control circuitry 308 uses communication circuitry 312 to wirelessly communicate information with individual devices.

[0061] Figure 4 Is with Figure 3 External devices 107 that communicate with the AMD 102 (e.g., Figure 1 This is a block diagram of a portion of an example of an external device 107 of a CRM system 100. External device 107 may be a programming device for an AMD 102. The programming device includes a storage device 418, programming control circuitry 416, a user interface 420, and communication circuitry 422. Programming control circuitry 416 may be implemented using an application-specific integrated circuit (ASIC) configured to perform one or more specific functions or general-purpose circuitry programmed to perform those functions. Among other things, general-purpose circuitry may include a microprocessor or a portion thereof, a microcontroller or a portion thereof, and programmable logic circuitry or a portion thereof. Storage device 418 may be a memory integrated with programming control circuitry 416 or a separate memory device. Communication circuitry 422 communicates wirelessly with the AMD 102 using near-field inductive wireless signals or far-field radio frequency signals. The programming device can be used to program pacing therapy parameters and other information in the AMD 102.

[0062] Back Figure 3 The patient's orientation information can be determined using the output of the posture sensor 314. Using the output from the posture sensor 314, the control circuit 308 can determine the elevation and lateral angles. Elevation angle It is the angle between the patient's torso and the horizontal plane.

[0063] Figures 5A-5C An example of patient orientation is shown. Figure 5A In the middle, the patient is standing upright at an angle of supine. .exist Figure 5B and Figure 5C In the middle, the patient is lying face up at a supine angle. When the patient is lying down, the lateral angle This indicates which side the patient is lying on. Figure 5B In the middle, the patient is shown lying supine at an angle of [missing information]. The side angle is also .exist Figure 5C In the middle, the patient is shown in a prone position with an upward angle of [missing information]. lateral angle is When the patient is lying on their right side, the supine angle is... The side angle is close to When the patient is lying on their left side, the supine angle is... The side angle is close to .

[0064] By monitoring the amount of time patients spend lying on their left side, the AMD 102 can detect when patients avoid lying on their left side. Trend analysis of information about patient orientation can provide information about disease progression.

[0065] Figure 6 This is a flowchart of a method 600 for operating a CRM system including an AMD 102 and an external device 107. The AMD 102 can be implanted in a patient or worn by the patient. The AMD 102 includes a posture sensor 314. The posture sensor 314 provides electrical posture sensor outputs representing the alignment of the corresponding first, second, and third non-parallel axes of the AMD 102 with the Earth's gravitational field.

[0066] The AMD 102 uses the output of posture sensor 314 to detect that the subject is stationary. For example, the posture sensor could be a multi-axis accelerometer, and the control circuitry 308 of the AMD 102 can detect that the subject is stationary when the patient's acceleration is below a threshold acceleration or when the accelerometer output is constant and does not change over time (e.g., due to Earth's gravitational field). In some examples, the control circuitry 308 can detect that the subject is stationary when the patient's average acceleration is below a threshold average acceleration value over a predetermined amount of time.

[0067] At block 605, when the subject is determined to be stationary, the AMD 102 uses the posture sensor output to determine that the subject should avoid lying on their left side. Control circuitry 308 can calculate the subject's elevation angle. and the lateral angle of the subject By storing information in the memory 316 of the AMD 102, the control circuitry 308 can record patient orientation information and the amount of time the patient spends in one or more detected orientations. At block 610, in response to determining that the subject avoids lying on their left side, the AMD 102 calculates measures of predicted sitting-up breathing and lateral recumbent breathing. The calculated measures can be a trend in the amount of time the patient is lying on their left side. This trend can be used to generate an indication of the patient's heart failure status.

[0068] Figure 7 An example of trend 700 is shown, illustrating the patient's lateral angle information. In this example, the trend begins with the patient lying on their left and right sides, then gradually stops at the end of the trend, with the patient lying on their left side. To create trend 700, when AMD 102 determines that the patient is stationary and the patient's supine angle... Less than At this time, control circuit 308 periodically (e.g., every ten minutes) records the patient's lateral angle. Control circuit 308 can be programmed to record lateral angles at other elevation angles or within a range of elevation angles. In some examples, when the calculated lateral angle is... or close to At this time, the patient's left-sided orientation can be identified. In some examples, a range of lateral angles (e.g.) are used. to This is used to identify the patient's left-side orientation.

[0069] In some examples, AMD 102 sends lateral angle information and the time spent in the lateral angle to external device 107. External device 107 calculates the amount of time the patient spends lying on their left side and can generate a trend 700 to display to the physician. The external device can use the orientation and time information to generate an indication of the patient's heart failure status. This indication can be presented on the display of external device 107. The heart failure status can be an indication of one or more of the patient's lateral recumbent breathing and orthopneic breathing. The indication of the heart failure status can be presented together with the trend 700 of the lateral angle information. Figure 7 In the example, an indication of heart failure status could be an alert that a patient's heart failure status is worsening, showing a trend of 700.

[0070] In some examples, the control circuitry 308 of the AMD 102 uses lateral angle information to determine when the patient is on their left side and calculates the amount of time the patient has been lying on their left side. The AMD 102 can use the communication circuitry 312 to send indications of the heart failure status (e.g., signals or messages) to an external device 107.

[0071] A potential complication is that the AMD 102 and posture sensor 314 may not be ideally oriented inside or on the patient's body, and the orientation may vary from patient to patient. In such cases, the posture sensor 314 may require "body calibration."

[0072] Figure 8 A coordinate system for the patient's body is shown. The body coordinate system uses the x, y, and z axes to describe the front-back, left-right, and up-down directions, respectively. Figure 9 The device coordinate system using the u, v, and w axes is shown in the figure. The ideal orientation of the AMD 102 is within the coronal plane, such that the device axes align with the body axes (e.g., ...). , , However, equipment orientation is usually not ideal.

[0073] Figure 10 This illustrates a more typical scenario where device coordinates deviate from body coordinates. As previously mentioned, this could be due to patient anatomy or the movement of the AMD 102. A calibration procedure is used to determine device orientation or convert device coordinates to body coordinates, allowing algorithms running on the medical device using posture sensing to correct the device orientation.

[0074] The calibration process involves determining the elements of a calibration matrix, which can be used to calculate a coordinate transformation to convert device coordinates to body coordinates. To determine the calibration matrix, the patient is placed in a first posture (e.g., an upright posture). Control circuitry 308 measures the output of the posture sensor against both axes. The patient is then placed in a second posture (e.g., a more supine posture than the upright posture), and control circuitry 308 again measures the output of the posture sensor against the same two axes.

[0075] Measurements for the two postures are used to calculate a calibration matrix. Once the calibration matrix is ​​determined, the posture sensor output is multiplied by the calibration matrix to generate an output calibrated to body coordinates. The calibration output of posture sensor 314 can be used to determine the patient's elevation and lateral angles. A method for calibrating a posture sensor can be found in U.S. Patent No. 10,328,267 to Hatlestad et al.

[0076] The manual steps of positioning the patient in a designated position and prompting the AMD 102 to calibrate its posture sensor 314 consume clinicians' time and effort, and sometimes the AMD 102's posture sensor 314 is not calibrated. Using an uncalibrated sensor, the AMD 102 cannot directly measure the elevation and lateral angles to independently assess the degree of orthopneic and lateral recumbent breathing. However, the AMD 102 can execute algorithms to calculate measures predicting orthopneic and lateral recumbent breathing using the axis of the posture sensor 314.

[0077] For example, the posture sensor 314 could be a multi-axis accelerometer. When the AMD 102 determines that the patient is stationary, the control circuit 308 performs acceleration measurements periodically throughout the day (e.g., every ten minutes). The measurement is the direction of the gravity vector relative to the accelerometer axis. When a new gravity vector is measured, the control circuit 308 calculates the angular change between the direction of the new gravity vector and the previously measured gravity vector. This produced and angular changes between The value of . In some examples, the angle change is calculated using the normalized vector dot product.

[0078] .

[0079] In some examples, trend analysis can be performed on the normalized vector dot product without inverse cosine, or

[0080] .

[0081] This can reduce the energy consumption used for calculations by the control circuit 308.

[0082] The maximum running value of the continuous angular change between gravity vector measurements was stored for multiple days (e.g., 7 to 28 days). This measurement may be referred to as the maximum gravitational vector angular change (Max GVAC). For approximately [time period missing] when the subject is lying down... The angle change can be assumed by the patient rolling from their left side to their right side and vice versa. The angle change shows a trend (by AMD 102, external device 107, or remote server 116). The maximum GVAC decreases when the patient is never lying on their left side.

[0083] Figure 11A The trend 700 of the side angle measurement using a calibrated multi-axis accelerometer is shown, and Figure 11B Trend 1100 of GVAC measured using an uncalibrated multiaxial accelerometer is shown. As described earlier in this document, lateral angle trend 700 shows the patient ceasing to lie on their left side at the end of the trend, and the trend shows the patient's lateral recumbent breathing. A comparison with GVAC trend 1100 shows that the maximum value of GVAC decreases as the patient stops lying on their left side (as indicated by arrow 1130).

[0084] The maximum value of GVAC also decreases when a patient's heart failure worsens and the patient begins to sleep at an elevated position. Figure 12A It represents the elevation angle of the rectangle representing the patient. The illustration. Figure 12B This indicates the patient after turning over. If the rectangle is in a supine position ( =0), then Figure 12A and Figure 12B The GVAC between will be the side angle However, because the rectangle increased the angle... GVAC decreased by 2 (or This indicates that the decrease in maximum GVAC in trend 1100 in Figure 11 can also detect orthopnea in the subjects.

[0085] Figure 13 Figure 1332 shows the average maximum GVAC values ​​from an uncalibrated accelerometer in heart failure (HF) patients who did not experience HF dyspnea events, and Figure 1334 shows the average maximum GVAC values ​​in heart failure patients who did experience HF dyspnea events. This figure shows that maximum GVAC values ​​are lower for high-risk patients. Therefore, maximum GVAC is an effective risk stratification indicator for hospitalization in heart failure.

[0086] In some examples, trend analysis can be performed on more angular changes over time, beyond the maximum value, to detect lateral and orthopnea. For example, the trend may include the percentile of the highest angular change, not just the maximum angular change. In some examples, the trend may include more than just continuous angular changes. For example, all angular changes occurring within a predetermined time window (e.g., a one-hour or two-hour time window).

[0087] By measuring maximum GVAC when the patient is asleep, not just at rest, the detection of lateral and orthopnea can be improved. The AMD 102 may include additional sensors (such as a heart rate sensor or respiratory rate sensor). The control circuitry 308 can use the output of the posture sensor 314, and the additional sensors can be used to detect whether the patient is asleep.

[0088] The systems, methods, and devices described herein provide for the collection and analysis of orientation data in device-based patients with heart failure. Data is collected using multi-axis posture sensors in devices worn or implanted in the patient. The data can be analyzed by a CRM system to monitor the patient's condition or progression.

[0089] Additional description

[0090] The above detailed description includes reference to the accompanying drawings, which form part of the detailed description. The drawings illustrate specific embodiments in which the invention can be practiced. These embodiments are also referred to herein as "examples". All publications, patents, and patent documents referenced in this document are incorporated herein by reference in their entirety as if individually incorporated. In the event of any inconsistency between the usage of this document and the documents incorporated by reference, the usage in the incorporated references shall be considered supplementary to the usage in this document; in the case of irreconcilable inconsistencies, the usage in this document shall prevail.

[0091] In this document, the terms “a” or “an” are used as commonly found in patent documents to include one or more, independent of any other instances or uses of “at least one” or “one or more.” In this document, the term “or” is used to refer to something non-exclusive, such that “A or B” includes “A but not B,” “B but not A,” and “A and B,” unless otherwise stated. In the appended claims, the terms “comprising” and “therein” are used as concise English equivalents to the corresponding terms “including” and “wherein.” Furthermore, in the following claims, the terms “comprising” and “including” are open-ended, meaning that a system, apparatus, article, or process that includes elements other than those listed after the term in a claim is still considered to fall within the scope of that claim. Additionally, in the following claims, the terms “first,” “second,” and “third,” etc., are used merely as labels and are not intended to impose numerical requirements on their subjects.

[0092] The methods described herein can be implemented, at least in part, by a machine or computer. Some examples may include a computer-readable medium or a machine-readable medium encoded with instructions operable to configure an electronic device to perform the methods described in the examples above. Implementations of these methods may include code, such as microcode, assembly language code, high-level language code, etc. Such code may include computer-readable instructions for performing various methods. The code may form part of a computer program product. Furthermore, during execution or at other times, the code may be tangibly stored on one or more volatile or non-volatile computer-readable media. These computer-readable media may include, but are not limited to, hard disks, removable disks, removable optical discs (e.g., optical discs and digital video discs), magnetic tape cassettes, memory cards or memory sticks, random access memory (RAM), read-only memory (ROM), etc. In some examples, a carrier medium may carry the code implementing these methods. The term "carrier medium" may be used to refer to a carrier wave carrying the code.

[0093] The foregoing description is intended to be illustrative and not limiting. For example, the foregoing examples (or one or more aspects thereof) may be used in combination with each other. Other embodiments may be used, such as those that a person skilled in the art would use after reading the foregoing description. The abstract is provided to comply with 37 CFR §1.72(b) so that the reader can quickly determine the nature of the technical disclosure. This document is submitted on the premise that it should not be construed as interpreting or limiting the scope or meaning of the claims. Furthermore, in the foregoing detailed description, various features may be combined to simplify this disclosure. This should not be construed as meaning that any unclaimed disclosed feature is essential to any claim. Rather, the subject matter of the invention may not be all the features of a particular disclosed embodiment, but only some of them. Therefore, the following claims are hereby incorporated into the detailed description, each claim existing independently as a separate embodiment. The scope of the invention should be determined by reference to the appended claims and the full scope of their equivalents.

Claims

1. A mobile medical device (AMD), the device comprising: A multi-axis attitude sensor is configured to provide an electrical attitude sensor output, the electrical attitude sensor output representing the alignment of the respective first non-parallel axis, second non-parallel axis, and third non-parallel axis of the AMD with the Earth's gravitational field; as well as The processing circuitry, communicatively coupled to the multi-axis attitude sensor, is configured to: The posture sensor output is used to determine that the subject should avoid lying on their left side; and In response to determining that the subject avoids lying on their left side, a measure is calculated to predict one or both of orthopneic and lateral respiration.

2. The device according to claim 1, wherein the processing circuit is configured to: The calibrated posture sensor output is used to detect that the subject is stationary; The calibrated posture sensor output is used to determine that the subject should avoid lying on their left side; and The amount of time the subject lay on their left side was calculated as the metric.

3. The device according to claim 1, wherein the processing circuit is configured to: The subject's elevation angle is calculated using the output of the posture sensor; The lateral angle of the subject is calculated using the output of the posture sensor; as well as The subject's supine angle is calculated to be within a predetermined range of supine supine angles, and the lateral angle indicates the amount of time the subject spends on their left side as the metric.

4. The device of claim 3, wherein the processing circuitry is configured to generate one or both of the subject’s sitting-up breathing and lying-down breathing states using a determined elevation angle and a determined lateral angle.

5. The device according to claim 1, wherein the processing circuit is configured to: Calculate the direction of the first gravity vector relative to the axis of the posture sensor; Calculate the direction of the second gravity vector relative to the axis of the posture sensor; Calculate the angular change between the second gravity vector and the first gravity vector; and Calculate the continuous angular change between the second gravity vector and the first gravity vector, and use the calculated continuous angular change to determine that the subject should avoid lying on his left side.

6. The device according to claim 5, wherein the processing circuit is configured to: Calculate the dot product of the second gravity vector and the first gravity vector to calculate the angular change between the second gravity vector and the first gravity vector.

7. The device according to claim 5, wherein the processing circuit is configured to: Calculate multiple gravity vectors and calculate multiple angular changes between the gravity vectors; Identify the predetermined percentile of the calculated angle change that has the highest value of the calculated angle change; Calculate the average value of the calculated angle changes; and Based on the average value of the calculated angle changes, it was determined that the subject should avoid lying on his left side.

8. The device according to any one of claims 1 to 7, The attitude sensor is a multi-axis accelerometer; and The processing circuit is configured as follows: The output of the multi-axis accelerometer is calibrated to the orientation of the AMD relative to the subject; and The calibrated output of the multi-axis accelerometer was used to determine that the subject was stationary and lying on his left side.

9. The device according to claim 8, comprising: A communication circuit that is operatively coupled to the processing circuit and configured to transmit information to a separate device; as well as The processing circuit is configured as follows: The amount of time the subject spent lying on their left side was used to generate an indication of the subject's heart failure status; and The instruction is sent to the individual device.

10. A method of operating a mobile medical device (AMD) that can be worn by a subject or implanted in the subject, the method comprising: The AMD's multi-axis posture sensor is used to determine that the subject avoids lying on his left side, wherein the posture sensor is configured to provide an electrical posture sensor output indicating the alignment of the AMD's respective first non-parallel axis, second non-parallel axis, and third non-parallel axis with the Earth's gravitational field. as well as In response to determining that the subject avoids lying on their left side, a measure is calculated to predict one or both of orthopneic and lateral respiration.

11. The method of claim 10, wherein calculating the metric comprises: The AMD performs trend analysis on the amount of time the subject spends lying on the left side; as well as Trends were used to generate an indication of the subject's heart failure status.

12. The method according to claim 10, in, Determining that the subject avoids lying on their left side includes: The subject's elevation angle is determined using the output of the calibrated posture sensor; The lateral angle of the subject is determined using the output of the calibrated posture sensor; and The calculation of the metrics includes trend analysis of the time the determined elevation and lateral angles indicate the subject's left side.

13. The method of claim 11, comprising: The determined elevation angle and the determined lateral angle are used to generate one or both of the subject's sitting and lying-back breathing states.

14. The method according to any one of claims 10-13, wherein, Determining that the subject avoids lying on their left side includes: Determine the direction of the current gravity vector relative to the axis of the attitude sensor; Calculate the angular change between the current gravity vector and the previously measured gravity vector relative to the axis of the attitude sensor; and Calculate multiple angle changes and use the determined angle changes to determine that the subject is on his left side.

15. The method of claim 14, further comprising determining the angle change using the dot product of the current gravity vector and a previously measured gravity vector.

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