Physiological monitoring after surgery using an implantable medical device

Abstract

An implantable medical device for implantation within a patient includes one or more sensors configured to sense an optical signal. Processing circuitry of the implantable medical device or of an external device may determine a blood pressure of the patient based on the optical signal sensed after the patient undergoes an invasive surgery, determine, based on a normal blood pressure range or a normal rate of blood pressure change over a particular period of time, that the blood pressure of the patient is abnormal, and, in response to determining that the blood pressure of the patient is abnormal, output an alert indicative of the blood pressure of the patient being abnormal.

Description

PHYSIOLOGICAL MONITORING AFTER SURGERY USING AN IMPLANTABLE MEDICAL DEVICE

[0001] This application claims the benefit of U.S. Provisional Patent Application Serial No. 63 / 678,426, filed August 1, 2024, the entire content of which is incorporated herein by reference.FIELD

[0002] The disclosure relates generally to medical devices and, more particularly, medical devices configured to monitor physiological parameters.BACKGROUND

[0003] Some types of medical systems may monitor various patient data of a patient or a group of patients to detect changes in health. In some examples, the medical system may monitor the data to detect one or more health conditions, such as arrhythmia, heart failure, congestion, etc. In some examples, the medical system may include one or more of an implantable medical device or a wearable device to collect the data based on sensing of physiological or other parameters of the patient.SUMMARY

[0004] In general, aspects of this disclosure are directed to an implantable medical device (IMD) that may be used to monitor physical parameters of a patient after the patient undergoes invasive surgery. The implantable device may be implanted in or near the heart of the patient, or may be implanted near the surgery site of the patient. The IMD may include sensors for sensing optical signals that may be used to determine physiological parameters of the patient, such as the blood pressure of the patient.

[0005] After the patient undergoes surgery, the IMD may continuously sense optical signals, such as photoplethysmographic (PPG) signals, and a device, such as the IMD or an external device, may track the blood pressure of the patient based on the optical signals. The device may determine whether the blood pressure of the patient is within a normal range of blood pressures and / or may determine whether changes in the blood pressure of the patient over time deviates from a normal rate of blood pressure change. If the device determines that the blood pressure of the patient is outside a normal range of bloodpressures and / or that the changes in the blood pressure of the patient over time deviates from a normal rate of blood pressure change, the device may output an alert to indicate to users, such as clinicians, the patient, and the like, that the blood pressure of the patient is abnormal.

[0006] In some aspects, the techniques described herein relate to a system including: an implantable medical device for implantation within a patient, the implantable medical device including one or more sensors configured to sense an optical signal; and processing circuitry configured to: determine a blood pressure of the patient based on the optical signal sensed after the patient undergoes an invasive surgery; determine, based on a normal blood pressure range or a normal rate of blood pressure change over a particular period of time, that the blood pressure of the patient is abnormal; and in response to determining that the blood pressure of the patient is abnormal, outputting an alert indicative of the blood pressure of the patient being abnormal.

[0007] In some aspects, the techniques described herein relate to a method including: sensing, by one or more sensors of an implantable medical device for implantation within a patient, an optical signal; determining, by processing circuitry, a blood pressure of the patient based on the optical signal sensed after the patient undergoes an invasive surgery; determining, by the processing circuitry, based on a normal blood pressure range or a normal rate of blood pressure change over a particular period of time, that the blood pressure of the patient is abnormal; and in response to determining that the blood pressure of the patient is abnormal, outputting, by the processing circuitry, an alert indicative of the blood pressure of the patient being abnormal.

[0008] In some aspect, the techniques described herein relate to an apparatus including: means for sensing an optical signal; means for determining a blood pressure of the patient based on the optical signal sensed after the patient undergoes an invasive surgery; means for determining, based on a normal blood pressure range or a normal rate of blood pressure change over a particular period of time, that the blood pressure of the patient is abnormal; and means for, in response to determining that the blood pressure of the patient is abnormal, outputting an alert indicative of the blood pressure of the patient being abnormal.

[0009] The summary is intended to provide an overview of the subject matter described in this disclosure. It is not intended to provide an exclusive or exhaustiveexplanation of the systems, device, and methods described in detail within the accompanying drawings and description below. Further details of one or more examples of this disclosure are set forth in the accompanying drawings and in the description below. Other features, objects, and advantages will be apparent from the description and drawings, and from the claims.BRIEF DESCRIPTION OF THE DRAWINGS

[0010] FIG. 1 illustrates example environment of an example medical system in conjunction with a patient, in accordance with techniques of this disclosure.

[0011] FIG. 2A is a perspective drawing illustrating an example insertable cardiac monitor, in accordance with techniques of this disclosure.

[0012] FIG. 2B is a perspective drawing illustrating another example insertable cardiac monitor, in accordance with techniques of this disclosure.

[0013] FIG. 3 is a functional block diagram illustrating an example configuration of an example medical device, in accordance with techniques of this disclosure.

[0014] FIG. 4 is a functional block diagram illustrating an example configuration of an example external device, in accordance with techniques of this disclosure.

[0015] FIG. 5 is a functional block diagram illustrating an example configuration of a health monitoring system, in accordance with techniques of this disclosure.

[0016] FIG. 6 is a block diagram illustrating an example system that includes a network and computing devices, in accordance with techniques of this disclosure.

[0017] FIG. 7 is a flow diagram illustrating an example technique according to the present disclosure.

[0018] FIG. 8 is a flow diagram that illustrates performing an example technique according to this disclosure.DETAILED DESCRIPTION

[0019] In general, aspects of this disclosure are directed to an implantable medical device (IMD) configured to monitor physiological parameters of a patient, such as the blood pressure of the patient after the patient undergoes invasive surgery. The IMD may be able to perform acute, ambulatory, and high resolution monitoring of blood pressures and other physiological parameters of patients in hospitals or home settings. Example implantable medical devices in accordance with techniques of this disclosure may include an insertable cardiac monitor such as the Reveal LINQ™ or LINQ II™ Insertable Cardiac Monitor (ICM), available from Medtronic, Inc. of Minneapolis, MN, a pacemaker / defibrillator, and the like.

[0020] When a patient suffers trauma or undergoes highly invasive surgeries, the physiological parameters of the patient may be more dynamic and / or inconsistent, such as due to medication changes, increases in movement, and the like. As such, an IMD may be used to perform short-term intensive monitoring of patients after such trauma or major surgeries. The IMD may be used in hospital, prior to surgery, in ambulatory care facilities, in home settings, and / or in any other locations outside of an intensive care unit (ICU) or critical care.

[0021] The IMD may be a temporary ambulatory pacing device. The IMD can be set to a higher resolution or higher power state to increase the accuracy and / or resolution of measurements made by the IMD, which may be useful for monitoring the physiological parameters of a patient for signs of heart failure decompensation, sudden cardiac arrest, or other cardiac conditions. The IMD may include sensors for sensing physiological signals of the patient, such as optical signals. Such optical signals may include photoplethysmographic (PPG) signals of the patient.

[0022] A monitoring device, such as the IMD or an external device, may monitor the blood pressure of the patient after surgery based on the optical signals, such as PPG signals, sensed by the IMD. The monitoring device may monitor the systolic and / or diastolic blood pressure of a patient based on the optical signals and may also monitor additional physiological parameters of the patient, such as the electrical activity of the patient’s heart, based on electrical signals sensed by the IMD.

[0023] The monitoring device may be programmed with thresholds (e.g., high and low thresholds) and / or a desired range for the monitored blood pressure, and may generate analert when the blood pressure of the patient is outside the thresholds and / or the desired range. The monitoring device may send such alerts to an external device or system to alert physicians, patients, and caregivers. Such thresholds and desired ranges may be physician driven or may be closed loop based on trends of the physiological parameters of the patient. In this way, the monitoring device may be able to quickly notify healthcare providers or caregivers when the patient’s blood pressure readings fall outside a safe range, which may enable immediate intervention in potentially life-threatening situations.

[0024] The measurement frequency and other parameters of the monitoring device may also be adjustable as needed. In emergency situations, such as a blood clot postsurgery when the patient is not at the hospital, the monitoring device may communicate with an external device or system to provide alerts directly to medical personnel or family / caregivers of the patient.

[0025] The IMD may be implanted in a patient prior to scheduled surgery, and the monitoring device may use optical signals, such as PPG signals, sensed by the IMD prior to the surgery to monitor the blood pressure and / or other physiological parameters prior to the surgery to establish baseline physiological parameters for the patient. Such baseline physiological parameters may be used as physiological parameter goals for patients to reach as part of their recovery. For example, the monitoring device may stop monitoring the blood pressure of the patient once the blood pressure of the patient reaches such baseline levels. In this way, the techniques of this disclosure may enable the monitoring device to provide personalized monitoring of patients based on the patients’ baseline blood pressure levels prior to surgery.

[0026] The monitoring device may calibrate the blood pressure monitoring algorithm by accepting an independent blood pressure reading from an independent calibration source, such as a cuff blood pressure monitor or an invasive blood pressure monitoring device (e.g., a catheter) that performs intra-arterial blood pressure monitoring of patient 4. By being able to accept an independent blood pressure reading and calibrating the blood pressure monitoring algorithm based on the independent blood pressure reading, the techniques of this disclosure may increase the accuracy of the monitoring device.

[0027] The monitoring device may also be able to accept other hypertension metrics, such as from blood work, urine analysis, and other labs. The monitoring device may accept such data from electronic medical records or may be able to download such datafrom other sources. The monitoring device may also be able to accept data from physician notes, patient notes, symptom markings, and / or family / caregiver / social circle inputs (e.g., encouragement, data points, etc.).

[0028] In some examples, the monitoring device may be able to send and receive physiological data of the patient to and from a wearable device worn by the patient. Such data may include physiological data not related to blood pressure. In some examples, the monitoring device may also receive sensor inputs from other sensors of the IMD, such as accelerometer data for activity, heart sounds, electrocardiogram (e.g., for arrhythmia detection due to medications), fluid status for water retention, and the like.

[0029] In some examples, the monitoring device may communicate with an external computing device or system to send the monitored data to the external device or system for display in a dashboard. Such a dashboard may allow physicians, patients, and caregivers to monitor physiological data, such as blood pressure, for the patient. The dashboard may present trends in the monitored blood pressure as well as other information such as trends, compliance, consistency, and the like.

[0030] The techniques of this disclosure may also provide certain technical advantages and improvements to the medical field of post-surgical monitoring of patients. Because a patient’s condition can change rapidly after undergoing invasive surgery, the techniques of this disclosure may enable continuous and real-time monitoring of blood pressure and other potentially vital physiological parameters of a patient that may aid in early detection and management of possible surgical complications.

[0031] Further, by using an IMD implanted in the patient to monitor blood pressure and other potentially vital physiological parameters of the patient, the techniques of this disclosure enable the patient to be monitored not just in hospitals but also at home or in other non-clinical environments. As such, the techniques of this disclosure supports ambulatory care, allowing patients to recover in the comfort of their homes without compromising on the quality of health monitoring for the patient. Such enhancements to patient comfort may also improve post-surgery patient outcomes.

[0032] FIG. 1 illustrates the environment of an example medical system 2 in conjunction with a patient 4, in accordance with one or more techniques of this disclosure. As shown in FIG. 1, medical system 2 includes an implantable medical device (IMD) 10 that may be in wireless communication with external device 12. In some examples,medical system 2 and / or external device 12 may be in wired or wireless communication with other devices not pictured in FIG. 1.

[0033] External device 12 may be a computing device. External device 12 may, in some examples, include or be communicably coupled to a display viewable by the user and an interface for receiving user input to external device 12. In some examples, external device 12 may be a notebook computer, tablet computer, workstation, one or more servers, cellular phone, personal digital assistant, a smartphone, a wearable device (e.g., a fitness tracker or a smartwatch), or another computing device that may run an application that enables the computing device to interact with IMD 10. External device 12 is configured to communicate with IMD 10 and, optionally, another computing device (not illustrated in FIG. 1), via wireless communication. External device 12, for example, may communicate via near-field communication 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., radiofrequency (RF) telemetry according to the 802.11 or Bluetooth® specification sets, or other communication technologies operable at ranges greater than near-field communication technologies).

[0034] External device 12 may be used to configure operational parameters and / or device settings for IMD 10. External device 12 may be used to retrieve data from IMD 10. The retrieved data may include values of physiological parameters measured by IMD 10, indications of health conditions detected by IMD 10, and physiological signals recorded by IMD 10. As will be discussed in greater detail below, one or more remote computing devices may interact with IMD 10 in a manner similar to external device 12, e.g., to program IMD 10 and / or retrieve data from IMD 10, via a network.

[0035] IMD 10 is a medical device implanted in patient 4. In some examples, IMD 10 is implanted in the heart of patient 4. In some examples, IMD 10 is implanted outside of a thoracic cavity of patient 4 (e.g., subcutaneously in the pectoral location illustrated in FIG. 1). In some examples, IMD 10 may be positioned near the sternum near or just below the level of the heart of patient 4, e.g., at least partially within the cardiac silhouette. In some examples, IMD 10 may be positioned on other locations, such as patient 4’s cranium region. In some examples, IMD 10 may be implanted in a particular location of patient 4’s body, such as at or near a surgical site, to monitoring healing for that location (e.g., limbs after limb reattachment, transplants, etc.). In some examples, IMD 10 takes the form of theReveal LINQ™ or LINQ II™ ICM. In some examples, the one or more sensors are configured to sense patient activity, e.g., one or more accelerometers.

[0036] IMD 10 includes one or more sensors (not shown in FIG. 1) and is configured to sense data via the one or more sensors. For example, IMD 10 may be configured to sense physiological signals such as photoplethysmographic (PPG) signals, electrical signals indicative of electrical activity of the patient 4’s heart, motion signals indicative of patient 4’s posture and / or activity level, and the like.. To capture such physiological signals, IMD 10 may include one or more sensors, such as an accelerometer, electrodes, one or more optical sensors, and the like. The one or more sensors may be configured to continuously (e.g., in a periodic and / or event-driven manner) sense for and capture signals.

[0037] IMD 10 and / or external device 12 may obtain the physiological signals sensed by the one or more sensors and to determine a physiological parameter of the patient. For example, IMD 10 and / or external device 12 may obtain optical signals, such as PPG signals, sensed by the one or more sensors and may determine, based on the optical signals, blood pressure of patient 4, such as the systolic blood pressure and / or the diastolic blood pressure of patient 4.

[0038] IMD 10 and / or external device 12 may be calibrated in order to more accurately sense physiological signals of patient 4. For example, IMD 10 and / or external device 12 may accept an independent blood pressure reading of patient 4 from an independent calibration source, such as a cuff blood pressure monitor, and IMD 10 and / or external device 12 may calibrate the blood pressure reading functionality of IMD 10 and / or external device 12, such as an algorithm used to determine the blood pressure of patient 4 from the sensed optical signal, based on the independent blood pressure reading. IMD 10 and / or external device 12 may calibrate the blood pressure reading functionality of IMD 10 and / or external device 12 so that the blood pressure reading determined by IMD 10 and / or external device 12 corresponds to the independent blood pressure reading. In addition or alternatively, IMD 10 and / or external device 12 may calibrate the blood pressure reading functionality of IMD 10 and / or external device 12 so the blood pressure reading functionality of IMD 10 and / or external device 12 is able to determine relative changes to blood pressure that corresponds to relative changes to the blood pressure that is determined by the independent calibration source.

[0039] In some examples, IMD 10 and / or external device 12 may be programmed to determine, based on the physiological signals, a physiological parameter of patient 4, such as the blood pressure of patient 4, according to a specific frequency and / or cadence. IMD 10 and / or external device 12 may be programmed to determine a physiological parameter of patient 4 more frequently right after patient 4’s surgical operation and to taper the frequency at which IMD 10 and / or external device 12 determines the physiological parameter over time post-surgery. For example, IMD 10 and / or external device 12 may be programmed to very frequently determine a physiological parameter of patient 4 the first two weeks post-surgery, such as every hour, every two hours, every 4 hours, and the like. After the first two weeks have passed, IMD 10 and / or external device 12 may be programmed to reduce the frequency at which IMD 10 and / or external device 12 determines the physiological parameter over time, and IMD 10 and / or external device 12 may be programmed to determine the physiological parameter once a day after thirty days post-surgery. In some examples, IMD 10 and / or external device 12 may be programmed to perform continuous (e.g., 24 hours a day, seven days a week) monitoring of patient 4 for an initial period (e.g., first two weeks) post-surgery. IMD 10 may be able to perform such continuous monitoring of patient 4 via use of a rechargeable battery that can be recharged via inductive charging or other wireless charging techniques.

[0040] IMD 10 and / or external device 12 may monitor the blood pressure of patient 4 and may, based on the blood pressure of patient 4, output an alert. For example, IMD 10 and / or external device 12 may be programmed with a desired range of blood pressure for patient 4. For example, IMD 10 and / or external device 12 may be programmed with one or more thresholds, such as a high threshold and / or a low threshold. IMD 10 and / or external device 12 may, in response to determining, based on the sensed physiological signals, that the blood pressure of patient 4 is outside the desired range, output an alert indicative of the blood pressure of patient 4 being outside the desired range.

[0041] Such an alert may be in the form of an audible alert (e.g., a sound), a haptic alert (e.g., vibrations), or a notification that is sent by IMD 10 and / or external device 12 to another device or system. For example, if IMD 10 and / or external device 12 includes a speaker device, IMD 10 and / or external device 12 may output an audible alert (e.g., a sound) indicative of the blood pressure of patient 4 being outside the desired range. In another example, IMD 10 may output the alert in the form of a notification to externaldevice 12, and external device 12 may, in response, correspondingly output an alert indicative of the blood pressure of patient 4 being outside the desired range, such as by outputting an audible alert or by displaying, at a display device of external device 12, a notification indicative of the blood pressure of patient 4 being outside the desired range. In further examples, IMD 10 and / or external device 12 may output the alert in the form of a notification to another device, such as another external device or to a remote system, and the other external device or remote system may, in response, correspondingly output an alert indicative of the blood pressure of patient 4 being outside the desired range, such as by outputting an audible alert or by displaying a notification indicative of the blood pressure of patient 4 being outside the desired range.

[0042] In some examples, IMD 10 and / or external device 12 may communicate with a remote system to send the monitored physiological parameters of patient 4 the remote system, and the remote system may provide a dashboard that allows physicians, patients, and caregivers to monitor physiological data, such as blood pressure, for the patient 4. The dashboard may present trends in the monitored blood pressure as well as other information such as trends, compliance, consistency, and the like.

[0043] For example, the dashboard may present details of the physiological parameters of patient 4, such as the blood pressure of patient 4 over time, enabling users to view how the physiological parameters of patient 4 are trending over time. Such a dashboard may be useful for tracking patient 4’s recovery after invasive surgery.

[0044] In some examples, the dashboard may present the blood pressure of patient 4, as determined by IMD 10 and / or external device 12 over time, such as in the form of a graph of the blood pressure of patient 4 over time. The graph may plot various other information regarding patient 4, such as the activity level of patient 4 over time, the posture of patient 4 over time, the specific times when patient 4 took doses of medication, times where patient 4 felt pain, the amount of pain felt by patient 4 over time, water retention levels of patient 4 over time, the heart rate of patient 4 over time against the high and low thresholds of the normal range of blood pressure over time, the rate of change in the heart rate of patient 4 over time against a normal rate of change of blood pressure over time, the ECG of patient 4 over time, heart sounds of patient 4 over time, the oxygen saturation (SpO2) of patient 4 over time, the tissue oxygen saturation (StO2) of patient 4 over time, the bioelectrical impedance of patient 4, or any other information that may behelpful for clinicians and other users to track patient 4’s recovery after surgery. The graph may also present additional information such as any data from patient 4’s electronic medical records, patient 4’s lab results such as blood work, urine analysis, and the like, patient 4’s schedule of physical therapy, physician’s notes, patient notes, symptom markings, and / or family / caregiver / social circle inputs (e.g., encouragement, data points, etc.).

[0045] FIG. 2A is a perspective drawing illustrating an IMD 10A, which may be an example configuration of IMD 10 of FIG. 1 as an ICM. In the example shown in FIG. 2 A, IMD 10A may be embodied as a monitoring device having housing 11, proximal electrode 16A and distal electrode 16B. Housing 11 may further comprise first major surface 14, second major surface 18, proximal end 20, and distal end 22. Housing 11 encloses electronic circuitry located inside the IMD 10A and protects the circuitry contained therein from body fluids. Housing 11 may be hermetically sealed and configured for subcutaneous implantation. Electrical feedthroughs provide electrical connection of electrodes 16A and 16B.

[0046] IMD 10A may include one or more optical sensors 67 (“optical sensor 67”), which may be placed at various locations on IMD 10 A.

[0047] In some examples, a battery or other power source of IMD 10 A, such as battery 31, may be included within housing 11. Because IMD 10A is designed for acute (i.e., short term), ambulatory monitoring of physiological parameters of patient 4 after surgery, as compared to chronic (i.e., long term) monitoring, the battery or power source may be designed to provide power for a relatively short period, such as two months or shorter. As such, the battery or power source of IMD 10A may be relatively much smaller than the battery or power source for an IMD that performs chronic monitoring, which may be designed to provide years of power. The battery or power source of IMD 10A may therefore take up less space within housing 11. The smaller size of the battery or power source in IMD 10A may provide space within housing 11 to include optical sensor 67 for sensing optical signals, such as PPG signals. In addition, the battery of IMD 10A may use high-rate battery chemistry that releases energy relatively more quickly compared to traditional battery chemistry for IMDs designed for low current drain applications. The high-rate battery chemistry of the battery of IMD 10A may be designed to support higher- power light emitting diodes (LEDs) and vertical -cavity surface-emitting lasers (VCSELs)of optical sensor 67 for light emission into a larger tissue volume. Supporting such LEDs and VCSELs of optical sensor 67 may enable a better signal to noise ratio for optical sensor 67 and may enable more accurate blood pressure reading of patient 4 based on the optical signals sensed by optical sensor 67.

[0048] In the example shown in FIG. 2A, IMD 10A is defined by a length / ., a width W and thickness or depth D and is in the form of an elongated rectangular prism wherein the length L is much larger than the width W, which in turn is larger than the depth D. In one example, the geometry of the IMD 10A - in particular a width W greater than the depth D - is selected to allow IMD 10A to be inserted under the skin of patient 4 using a minimally invasive procedure and to remain in the desired orientation during insertion. For example, the device shown in FIG. 2A includes radial asymmetries (notably, the rectangular shape) along the longitudinal axis that maintains the device in the proper orientation following insertion. For example, the spacing between proximal electrode 46 A and distal electrode 46B may range from 5 millimeters (mm) to 55 mm, 30 mm to 55 mm, 35 mm to 55 mm, and from 40 mm to 55 mm and may be any range or individual spacing from 5 mm to 60 mm. In addition, IMD 10A may have a length L that ranges from 30 mm to about 70 mm. In other examples, the length L may range from 5 mm to 60 mm, 40 mm to 60 mm, 45 mm to 60 mm and may be any length or range of lengths between about 30 mm and about 70 mm. In addition, the width W of major surface 14 may range from 3 mm to 15, mm, from 3 mm to 10 mm, or from 5 mm to 15 mm, and may be any single or range of widths between 3 mm and 15 mm. The thickness of depth D of IMD 10A may range from 2 mm to 15 mm, from 2 mm to 9 mm, from 2 mm to 5 mm, from 5 mm to 15 mm, and may be any single or range of depths between 2 mm and 15 mm. In addition, IMD 10A according to an example of the present disclosure is has a geometry and size designed for ease of implant and patient comfort. Examples of IMD 10A described in this disclosure may have a volume of three cubic centimeters (cm) or less, 1.5 cubic cm or less or any volume between three and 1.5 cubic centimeters.

[0049] In the example shown in FIG. 2 A, once inserted within patient 4, the first major surface 14 faces outward, toward the skin of patient 4 while the second major surface 18 is located opposite the first major surface 14. In addition, in the example shown in FIG. 2A, proximal end 20 and distal end 22 are rounded to reduce discomfort and irritation to surrounding tissue once inserted under the skin of patient 4. IMD 10A, includinginstrument and method for inserting IMD 10 is described, for example, in U.S. Patent Publication No. 2014 / 0276928, incorporated herein by reference in its entirety.

[0050] Proximal electrode 16A is at or proximate to proximal end 20, and distal electrode 16B is at or proximate to distal end 22. Proximal electrode 16A and distal electrode 16B are used to sense cardiac EGM signals, e.g., ECG signals, thoracically outside the ribcage, which may be sub-muscularly or subcutaneously. EGM signals may be stored in a memory of IMD 10 A, and data may be transmitted via integrated antenna 30A to another device, which may be another implantable device or an external device, such as external device 12. In some example, electrodes 16A and 16B may additionally or alternatively be used for sensing any bio-potential signal of interest, which may be, for example, an EGM, EEG, EMG, or a nerve signal, or for measuring impedance, from any implanted location.

[0051] In the example shown in FIG. 2A, proximal electrode 16A is at or in close proximity to the proximal end 20 and distal electrode 16B is at or in close proximity to distal end 22. In this example, distal electrode 16B is not limited to a flattened, outward facing surface, but may extend from first major surface 14 around rounded edges 24 and / or end surface 26 and onto the second major surface 18 so that the electrode 16B has a three-dimensional curved configuration. In some examples, electrode 16B is an uninsulated portion of a metallic, e.g., titanium, part of housing 11.

[0052] In the example shown in FIG. 2A, proximal electrode 16A is located on first major surface 14 and is substantially flat, and outward facing. However, in other examples proximal electrode 16A may utilize the three dimensional curved configuration of distal electrode 16B, providing a three dimensional proximal electrode (not shown in this example). Similarly, in other examples distal electrode 16B may utilize a substantially flat, outward facing electrode located on first major surface 14 similar to that shown with respect to proximal electrode 16 A.

[0053] The various electrode configurations allow for configurations in which proximal electrode 16A and distal electrode 16B are located on both first major surface 14 and second major surface 18. In other configurations, such as that shown in FIG. 2 A, only one of proximal electrode 16A and distal electrode 16B is located on both major surfaces 14 and 18, and in still other configurations both proximal electrode 16A and distal electrode 16B are located on one of the first major surface 14 or the second major surface18 (e.g., proximal electrode 16A located on first major surface 14 while distal electrode 16B is located on second major surface 18). In another example, IMD 10A may include electrodes on both major surface 14 and 18 at or near the proximal and distal ends of the device, such that a total of four electrodes are included on IMD 10 A. Electrodes 16A and 16B may be formed of a plurality of different types of biocompatible conductive material, e.g. stainless steel, titanium, platinum, iridium, or alloys thereof, and may utilize one or more coatings such as titanium nitride or fractal titanium nitride.

[0054] In the example shown in FIG. 2A, proximal end 20 includes a header assembly 28 that includes one or more of proximal electrode 16 A, integrated antenna 30 A, antimigration projections 32, and / or suture hole 34. Integrated antenna 30A is located on the same major surface (i.e., first major surface 14) as proximal electrode 16A and is also included as part of header assembly 28. Integrated antenna 30A allows IMD 10A to transmit and / or receive data. In other examples, integrated antenna 30A may be formed on the opposite major surface as proximal electrode 16 A, or may be incorporated within the housing 11 of IMD 10A. In the example shown in FIG. 2A, anti-migration projections 32 are located adjacent to integrated antenna 30A and protrude away from first major surface 14 to prevent longitudinal movement of the device. In the example shown in FIG. 2 A, anti-migration projections 32 include a plurality (e.g., nine) small bumps or protrusions extending away from first major surface 14. As discussed above, in other examples antimigration projections 32 may be located on the opposite major surface as proximal electrode 16A and / or integrated antenna 30A. In addition, in the example shown in FIG. 2A, header assembly 28 includes suture hole 34, which provides another means of securing IMD 10A to patient 4 to prevent movement following insertion. In the example shown, suture hole 34 is located adjacent to proximal electrode 16A. In one example, header assembly 28 is a molded header assembly made from a polymeric or plastic material, which may be integrated or separable from the main portion of IMD 10 A.

[0055] FIG. 2B is a perspective drawing illustrating another IMD 10B, which may be another example configuration of IMD 10 from FIG. 1 as an ICM. IMD 10B of FIG. 2B may be configured substantially similarly to IMD lOA of FIG. 2A, with differences between them discussed herein.

[0056] IMD 10B may include a leadless, subcutaneously-implantable monitoring device, e.g. an ICM. IMD 10B includes housing having a base 40 and an insulative cover42. Proximal electrode 16C and distal electrode 16D may be formed or placed on an outer surface of cover 42. Various circuitries and components of IMD 10B, e.g., described below with respect to FIG. 3, may be formed or placed on an inner surface of cover 42, or within base 40. IMD 10B may also include optical sensor 67.

[0057] In some examples, a battery or other power source of IMD 10B may be included within base 40. Because IMD 10B is designed for acute (i.e., short term), ambulatory monitoring of physiological parameters of patient 4 after surgery, as compared to chronic (i.e., long term) monitoring The battery or power source may be designed to provide power for a relatively short period, such as two months or shorter. As such, the battery or power source of IMD 10B may be relatively much smaller than the battery or power source for an IMD that performs chronic monitoring, which may be designed to provide years of power. As such, the battery or power source of IMD 10B may take up less space within IMD 10B. The smaller size of the battery or power source in IMD 10B may provide space within IMD 10B for IMD 10B to include optical sensor 67 for sensing optical signals, such as PPG signals. In addition, the battery of IMD 10B may use high- rate battery chemistry that releases energy relatively more quickly compared to traditional battery chemistry for IMDs designed for low current drain applications. The high-rate battery chemistry of the battery of IMD 10B may be designed to support higher-power light emitting diodes (LEDs) and vertical-cavity surface-emitting lasers (VCSELs) of optical sensor 67 for light emission into a larger tissue volume. Supporting such LEDs and VCSELs of optical sensor 67 may enable a better signal to noise ratio for optical sensor 67 and may enable more accurate blood pressure reading of patient 4 based on the optical signals sensed by optical sensor 67.

[0058] In the illustrated example, antenna 30B is formed or placed on the outer surface of cover 42, but may be formed or placed on the inner surface in some examples. In some examples, insulative cover 42 may be positioned over an open base 40 such that base 40 and cover 42 enclose the circuitries and other components and protect them from fluids such as body fluids. The housing including base 40 and insulative cover 42 may be hermetically sealed and configured for subcutaneous implantation.

[0059] Circuitries and components may be formed on the inner side of insulative cover 42, such as by using flip-chip or wire bond integrated circuit packaging technology. Insulative cover 42 may be flipped onto a base 40. When flipped and placed onto base 40,the components of IMD 10B formed on the inner side of insulative cover 42 may be positioned in a gap 44 defined by base 40. Electrodes 16C and 16D and antenna 30B may be electrically connected to circuitry formed on the inner side of insulative cover 42 through one or more vias (not shown) formed through insulative cover 42. Insulative cover 42 may be formed of sapphire (i.e., corundum), glass, parylene, and / or any other suitable insulating material. Base 40 may be formed from titanium or any other suitable material (e.g., a biocompatible material). Electrodes 16C and 16D may be formed from any of stainless steel, titanium, platinum, iridium, or alloys thereof. In addition, electrodes 16C and 16D may 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.

[0060] In the example shown in FIG. 2B, the housing of IMD 10B defines a length / ., a width W and thickness or depth D and is in the form of an elongated rectangular prism wherein the length L is much larger than the width W, which in turn is larger than the depth D, similar to IMD 10A of FIG. 2A. For example, the spacing between proximal electrode 46C and distal electrode 46D may range from 5 mm to 50 mm, from 30 mm to 50 mm, from 35 mm to 45 mm, and may be any single spacing or range of spacings from 5 mm to 50 mm, such as approximately 40 mm. In addition, IMD 10B may have a length L that ranges from 5 mm to about 70 mm. In other examples, the length L may range from 30 mm to 70 mm, 40 mm to 60 mm, 45 mm to 55 mm, and may be any single length or range of lengths from 5 mm to 50 mm, such as approximately 45 mm. In addition, the width may range from 3 mm to 15 mm, 5 mm to 15 mm, 5 mm to 10 mm, and may be any single width or range of widths from 3 mm to 15 mm, such as approximately 8 mm. The thickness or depth D of IMD 10B may range from 2 mm to 15 mm, from 5 mm to 15 mm, or from 3 mm to 5 mm, and may be any single depth or range of depths between 2 mm and 15 mm, such as approximately 4 mm. IMD 10B may have a volume of three cubic centimeters (cm) or less, or 1.5 cubic cm or less, such as approximately 1.4 cubic cm.

[0061] In the example shown in FIG. 2B, once inserted subcutaneously within patient 4, outer surface of cover 42 faces outward, toward the skin of patient 4. In addition, as shown in FIG. 2B, proximal end 46 and distal end 48 are rounded to reduce discomfort and irritation to surrounding tissue once inserted under the skin of patient 4. In addition, edges of IMD 10B may be rounded.

[0062] FIG. 3 is a functional block diagram illustrating an example configuration of IMD 10 of FIG. 1 in accordance with one or more techniques described herein. In the illustrated example, IMD 10 includes electrodes 16 (e.g., corresponding to any of electrodes 16A-16D), antenna 27, processing circuitry 50, sensing circuitry 52, communication circuitry 54, storage device 56, switching circuitry 58, and sensors 62. Processing circuitry 50 may be operatively coupled to sensing circuitry 52, communication circuitry 54, storage device 56, switching circuitry 58, and sensors 62. Although the illustrated example includes two electrodes 16, IMDs including or coupled to more than two electrodes 16 may implement the techniques of this disclosure in some examples. IMD 10 further comprises a power source 64 to provide operational power for processing circuitry 50, sensing circuitry 52, communication circuitry 54, storage device 56, switching circuitry 58, and sensors 62.

[0063] Processing circuitry 50 may be configured to implement functionality and / or execute instructions within IMD 10. For example, processing circuitry 50 may receive and execute instructions that provide the functionality described herein, such as in FIG. 1. Processing circuitry 50 may include fixed function circuitry and / or programmable processing circuitry. Processing circuitry 50 may 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 circuitry 50 may 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 circuitry 50 herein may be embodied as software, firmware, hardware or any combination thereof.

[0064] Sensing circuitry 52 may be configured to sense cardiac activity of patient 4. In some examples, sensing circuitry 52 may be selectively coupled to electrodes 16 via switching circuitry 58, e.g., to sense electrical signals of the heart of patient 4. For example, sensing circuitry may select electrodes 16 and polarity, referred to as the sensing vector, used to sense cardiac activity data (e.g., electrocardiogram (ECG) data, electrogram (EGM) data, etc.) as controlled by processing circuitry 50. Processing circuitry 50 may detect arrhythmias based on cardiac activity data. In some examples, electrodes 16 may be configured to sense a parameter indicative of heart failure, andprocessing circuitry 50 may be configured to determine a risk of heart failure further based on the parameter indicative of heart failure. For example, electrodes 16 may measure subcutaneous tissue or interstitial impedance values, respiratory rate, heart rate (e.g., day and / or night heart rate), QRS morphology, HRV (e.g., day and / or night HRV), etc.

[0065] In some examples, sensing circuitry 52 may include one or more filters and amplifiers for filtering and amplifying signals received from electrodes 16 and / or sensors 62. Sensing circuitry 52 and processing circuitry 50 may store patient data in storage device 56, e.g., digitized samples of electrical signals. Sensing circuitry 52 may also monitor signals from sensors 62 and may send signals captured by sensors 62 to processing circuitry 50 for processing. Sensing circuitry 52 may capture sensor signals from any one of sensors 62, e.g., to produce other patient data, in order to facilitate monitoring of patient activity and detecting changes in patient health.

[0066] Sensors 62 may include one or more multi-axial accelerometers 65 (“accelerometer 65”), one or more optical sensors 67 (“optical sensor 67”), pressure sensors, as examples. Accelerometer 65 and PPG sensor 67 may each be configured to continuously (e.g., in a periodic and / or event-driven manner) sense for and capture physiological signals of patient 4. While FIG. 3 illustrates sensors 62 as including accelerometer 65 and optical sensor 67, sensors 62 may, in some examples, include additional sensing circuitry, such as blood oxygen saturation sensing circuitry, blood volume sensing circuitry, heart rate sensing circuitry, temperature sensing circuitry, or any combination thereof.

[0067] Accelerometer 65 may be any device configured to measure the proper acceleration of IMD 10 and to generate a signal indicative of the proper acceleration of IMD 10. Optical sensor 67 may be any device configured to measure volumetric variations of blood circulation, such as blood volume changes in the microvascular bed of tissue. Optical sensor 67 may include a light source and a photodetector. The light source may emit light into the tissue of patient 4, and the photodetector may measure the amount of light either transmitted through or reflected back from the tissue of patient 4. Optical sensor 67 may be configured to generate, based on the amount of light either transmitted through or reflected back from the tissue of patient 4, an optical signal, which may include a PPG signal.

[0068] Communication circuitry 54, which may be an example of the communicationcircuitry described in FIG. 1, may include any suitable hardware, firmware, software or any combination thereof for wirelessly communicating with another device, such as external device 12, another networked computing device, or another IMD or sensor. Under the control of processing circuitry 50, communication circuitry 54 may receive downlink telemetry from, as well as send uplink telemetry to external device 12 or another device with the aid of an internal or external antenna, e.g., antenna 27. In addition, processing circuitry 50 may communicate with a networked computing device via an external device (e.g., external device 12) and a computer network, such as the Medtronic CareLink® Network. Antenna 27 and communication circuitry 54 may be configured to transmit and / or receive signals via inductive coupling, electromagnetic coupling, Near Field Communication (NFC), Radio Frequency (RF) communication, Bluetooth, WiFi, or other proprietary or non-proprietary wireless communication schemes.

[0069] In some examples, processing circuitry 50 may control communication circuitry 54 to transmit data to another device, e.g., external device 12 or a cloud computing system comprising one or more computing devices, for analysis, including the determining of various sleep properties of patient 4. In this manner, the techniques of this disclosure may advantageously enable improved accuracy in the detection of changes in patient health and, consequently, better evaluation of the condition of patient 4.

[0070] In some examples, storage device 56 includes computer-readable instructions that, when executed by processing circuitry 50, cause IMD 10 and processing circuitry 50 to perform various functions attributed to IMD 10 and processing circuitry 50 herein. Storage device 56 may include any volatile, non-volatile, magnetic, optical, or electrical media, such as a random-access memory (RAM), read-only memory (ROM), non-volatile RAM (NVRAM), electrically-erasable programmable ROM (EEPROM), ferroelectric RAM (FRAM), dynamic random-access memory (DRAM), flash memory, or any other digital media. Storage device 56 may store, as examples, programmed values for one or more operational parameters of IMD 10 and / or data collected by IMD 10 for transmission to another device using communication circuitry 54. Data stored by storage device 56 and transmitted by communication circuitry 54 to one or more other devices may include patient data (e.g., physiological characteristics, sounds and vibrations captured by sensors 62, etc.).

[0071] Processing circuitry 50 may obtain signals from sensors 62 and / or from sensingcircuitry 52 and may determine, based on the signals, a physiological parameter of patient 4. Such signals may include physiological signals sensed by sensors 62 and / or from sensing circuitry 52. Processing circuitry 50 may determine, based on the signals obtained from sensors 62 and / or from sensing circuitry 52, the blood pressure of patient 4, such as the systolic blood pressure and / or the diastolic blood pressure of patient 4. For example, processing circuitry 50 may determine, based on the optical signal, such as the PPG signal, sensed by sensors 62 and / or from sensing circuitry 52, the blood pressure of patient 4 using any suitable technique for determining the blood pressure from optical signals.

[0072] In some examples, processing circuitry 50 may determine, based on the signals obtained from sensors 62 and / or from sensing circuitry 52, other physiological parameters of patient 4. For example, processing circuitry 50 may obtain motion signals generated by accelerometer 65 and may determine, based on the motion signals, an activity level of patient 4 and / or a posture of patient 4 (e.g., whether patient 4 is laying down, standing up, sitting, etc.). In other examples, processing circuitry may determine, based on the signals obtained from sensors 62 and / or from sensing circuitry 52, physiological parameters of patient 4 such as the blood oxygen saturation of patient 4, the heart rate of patient 4, the temperature of patient 4, an ECG, an EEG, and the like.

[0073] Processing circuitry 50 may use a blood pressure measurement algorithm 55 to determine, based on optical signals sensed by sensors 62 and / or from sensing circuitry 52, the blood pressure of patient 4. Processing circuitry 50 may calibrate the blood pressure measurement algorithm 55 based on an independent blood pressure reading from an independent calibration source, such as a cuff blood pressure monitor. Calibrating the blood pressure measurement algorithm 55 may enable processing circuitry 50 to more accurately sense physiological signals of patient 4.

[0074] Processing circuitry 50 may calibrate the blood pressure measurement algorithm 55 such that the blood pressure of patient 4 determined using the blood pressure measurement algorithm 55 matches the independent blood pressure reading from the independent calibration source. In addition or alternatively, processing circuitry 50 may calibrate blood pressure measurement algorithm 55 so that blood pressure measurement algorithm 55 is able to determine relative changes to blood pressure that matches to relative changes to the blood pressure that is determined by the independent calibration source. That is, if the independent calibration source determines independent bloodpressure readings at two different points in time that changes by a specific millimeters Mercury (mmHg) or by a specific percentage (e.g., 20%), processing circuitry 50 may calibrate the blood pressure measurement algorithm 55 to determine blood pressures of patient 4 at the same two different points in time that also change by the same specific mmHg or by the same specific percentage.

[0075] In some examples, processing circuitry 50 may determine, based on the physiological signals, a physiological parameter of patient 4, such as the blood pressure of patient 4, according to a specific frequency, schedule, and / or cadence. Processing circuitry 50 may more frequently determine the blood pressure of patient 4 based on signals obtained from sensors 62 and / or from sensing circuitry 52 during an initial period after patient 4 undergoes a surgical operation, such as the first two weeks post-surgery. Processing circuitry 50 may also reduce the frequency at which processing circuitry 50 determines the blood pressure of patient 4 over time. For example, processing circuitry 50 may very frequently determine the blood pressure of patient 4 during an initial postsurgery period, such as every hour, every two hours, every 4 hours, and the like.

[0076] Processing circuitry 50 may reduce the frequency at which processing circuitry 50 determines the blood pressure of patient 4 over time after the initial post-surgery period. For example, after the initial post-surgery period, processing circuitry 50 may gradually reduce the frequency at which processing circuitry 50 determines the blood pressure of patient 4 over time, such that, after thirty days post-surgery, processing circuitry 50 may determine the blood pressure of patient 4 once a day.

[0077] Processing circuitry 50 may also be programmed to determine the blood pressure of patient 4 according to specified schedules and / or at specified frequencies. For example, a doctor for patient 4 may interact with a device, such as external device 12, to input a specific schedule and / or frequency for determining the blood pressure of patient 4, and the device may communicate with IMD 10 to program processing circuitry 50 to determine the blood pressure of patient 4 according to the inputted schedule and / or at the inputted frequency. Processing circuitry 50 may store the schedule and / or frequency for determining the blood pressure of patient 4 as blood pressure (BP) schedule 57.

[0078] In some examples, processing circuitry 50 may adjust the schedule and / or frequency for determining the blood pressure of patient 4 based on any other suitable factors, such as the physiological condition of patient 4 and / or other external factors. Forexample, if processing circuitry 50 determines that the blood pressure of patient 4 is in a hypertensive range (e.g., 140 / 90 mmHg or higher), processing circuitry 50 may increase the frequency at which processing circuitry 50 determines the blood pressure of patient 4. When processing circuitry 50 determines that the blood pressure of patient 4 is below the hypertensive range, processing circuitry 50 may lower the frequency at which processing circuitry 50 determines the blood pressure of patient 4.

[0079] In some examples, processing circuitry 50 may determine an activity level of patient 4 and may, in response to determining that the activity level of patient 4 corresponds to patient 4 being physically active (e.g., walking, running, etc.), determine the blood pressure of patient 4 to determine whether the blood pressure of patient 4 is abnormal while patient 4 is being physically active. Processing circuitry 50 may determine the activity level of patient 4 via any suitable technique. For example, processing circuitry 50 may communicate with an external device, such as external device 12 or a wearable device (e.g., a fitness tracker or a smart watch) being worn by patient 4, that tracks the activity level of patient 4, and may receive, from the external device, a signal indicative of the activity level of patient 4. In some examples, processing circuitry 50 may determine the activity level of patient 4 by receiving motion signals from accelerometer 65 or from an external device, and may determine, via any suitable technique, an activity level of patient 4 based on the motion signals.

[0080] Processing circuitry 50 may receive any other information from an external device (e.g., external device 12, another device, or a remote system) that patient monitoring module 102 may use to adjust the schedule, frequency, and / or cadence of determining the blood pressure of patient 4. For example, processing circuitry 50 may receive hypertension metrics of patient 4, such as from blood work, urine analysis, and other labs, data from patient 4’s electronic medical records, physician notes regarding patient 4, patient notes by patient 4, and the like. Processing circuitry 50 may also receive additional physiological parameters of patient 4, such as heart sounds, ECGs, fluid retention status, and the like.

[0081] In some examples, processing circuitry 50 may determine that patient 4 has undergone surgery and may, in response to determining that patient 4 has undergone the surgery, start determining blood pressure of patient 4 according to the specified schedule, frequency, and / or cadence. That is, processing circuitry 50 may not start periodicallydetermining the blood pressure of patient 4 until processing circuitry 50 has determined that patient 4 has undergone the surgery and the surgery has been completed. For example, processing circuitry 50 may receive, from external device 12, a signal indicative of patient 4 having undergone surgery. Processing circuitry 50 may, in response to receiving the signal indicative of patient 4 having undergone the surgery, start determining the blood pressure of patient 4 according to the specified schedule, frequency, and / or cadence.

[0082] Processing circuitry 50 may generate an output based on the physiological signals of patient 4 sensed by sensors 62 and / or sensing circuitry 52. In some examples, processing circuitry 50 may continuously obtain the physiological signals of patent 4 sensed by sensors 62 and / or from sensing circuitry 52 and output the physiological signals of patent 4 to an external device or remote system, such as to external device 12.

[0083] In some examples, processing circuitry 50 may monitor the blood pressure of patient 4 and may, based on the blood pressure of patient 4, output an alert. Such an alert may be in the form of an audible alert (e.g., a sound), a haptic alert (e.g., vibrations), or a notification that is sent to another device or system (e.g., to external device 12 and / or a remote system). For example, if IMD 10 includes a speaker device, processing circuitry 50 may cause the speaker device to output an audible alert (e.g., a sound). In another example, processing circuitry 50 may output the alert in the form of a notification to another device, such as external device 12 or a remote system. External device 12 or the remote system may, in response, correspondingly output an alert, such as by outputting an audible alert or by displaying a notification indicative of the blood pressure of patient 4.

[0084] In some examples, processing circuitry 50 may determine whether the blood pressure of patient 4 is abnormal. Processing circuitry 50 may, in response to determining that the blood pressure of patient 4 is abnormal, output an alert indicative of the blood pressure of patient 4 is abnormal. Processing circuitry 50 may be programmed with or may otherwise determine a normal blood pressure range for patient 4. For example, processing circuitry 50 may be programmed with or may determine one or more thresholds, such as a high threshold and / or a low threshold. Processing circuitry 50 may, in response to determining that the blood pressure of patient 4 is outside the normal blood pressure range, output an alert indicative of the blood pressure of patient 4 being abnormal. Processing circuitry 50 may store the normal blood pressure range in normal blood pressure (BP) data 59 in storage device 56.

[0085] In some examples, processing circuitry 50 may determine a normal blood pressure range of patient 4 based on determining a baseline blood pressure of patient 4 prior to patient 4’s surgery. As described throughout this disclosure, IMD 10 may be inserted prior to patient 4 undergoes surgery to measure baseline physiological signals, which are physiological signals of patient 4 prior to undergoing surgery. The baseline physiological signals of patient 4 may include baseline optical signals of patient 4, such as baseline PPG signals. Processing circuitry 50 may, based on the baseline optical signals, determine baseline blood pressure levels of patient 4, For example, processing circuitry 50 may determine, over a period of time, the baseline blood pressure levels of patient 4 during the period of time.

[0086] Processing circuitry 50 may determine the normal blood pressure range of patient 4 based on the baseline blood pressure levels of patient 4. For example, processing circuitry 50 may determine the average baseline blood pressure level of patient 4 over a particular period of time. Processing circuitry 50 may determine the normal blood pressure range to have a high threshold that is a specified millimeters Mercury (mmHg) above the average baseline blood pressure level, or may determine the normal blood pressure range to have a high threshold that is a specified percentage above the average baseline blood pressure level. Similarly, processing circuitry 50 may determine the normal blood pressure range to have a low threshold that is a specified mmHg below the average blood pressure level, or may determine the normal blood pressure range to have a low threshold that is a specified percentage below the average baseline blood pressure level.

[0087] In some examples, processing circuitry 50 may determine a normal blood pressure range of patient 4 that changes over time. For example, if the blood pressure of patient 4 normally rise by a specific slope over time post-surgery, processing circuitry 50 may also determine a normal blood pressure range of patient 4 that rises according to the specific slope over time. That is, processing circuitry 50 may determine an initial normal blood pressure range and may determine a slope by which the high threshold and the low threshold of the normal blood pressure range rises over time. If processing circuitry 50 determines that the blood pressure of patient 4 rises by more than the specific slope, such that the blood pressure of patient 4 is not within the determined normal blood pressure range, processing circuitry 50 may determine that the blood pressure of patient 4 is abnormal.

[0088] In some examples, processing circuitry 50 may determine a normal rate of blood pressure change over a particular time period. Examples of a normal rate of blood pressure change may be an increase by 10 millimeters mercury (mmHg) over a particular time, an increase by 20%, and the like. The particular time period may be over an hour, over two hours, over twelve hours, over twenty four hours and the like. Processing circuitry 50 may determine a rate of change in the blood pressure of patient 4 and may compare the rate of change in the blood pressure of patient 4 over a particular time period to the normal rate of blood pressure change over the particular time period to determine whether the blood pressure of patient 4 is abnormal. For example, processing circuitry 50 may determine whether the rate at which the blood pressure of patient 4 has increased over the particular time period is greater than a normal rate of blood pressure increase over the particular time period. Processing circuitry 50 may, responsive to determining that the rate at which the blood pressure of patient 4 has increased over the particular time period is greater than the normal rate of blood pressure increase over the particular time period, determine that the blood pressure of patient 4 is abnormal. Processing circuitry 50 may store the normal rate of blood pressure change over a particular time period in normal blood pressure (BP) data 59 in storage device 56.

[0089] In some examples, processing circuitry 50 may dynamically adjust the normal blood pressure range of patient 4 and / or the normal rate of blood pressure change over a particular time period based on factors such as time, the activity level of patient 4, the posture of patient 4, or other factors. The blood pressure of a patient may increase while the patient is highly active and may decrease when the patient is relatively less active. As such, processing circuitry 50 may increase the normal blood pressure range of patient 4 and / or the normal rate of blood pressure change of patient 4 when processing circuitry 50 detects that the activity level of patient 4 is high, and / or may decrease the normal blood pressure range of patient 4 and / or the normal rate of blood pressure change of patient 4 when processing circuitry 50 detects that the activity level of patient 4 is low.

[0090] For example, processing circuitry 50 may determine the activity level of patient 4 as low, normal, or high, where a low activity level may denote that patient 4 is completely at rest (e.g., sleeping or sitting still), and where a high activity level may denote that patient 4 is physically exerting themselves (e.g., walking, running, lifting weights, etc.). Processing circuitry 50 may receive, from the external device an indicationof the activity level of patient 4. Processing circuitry 50 may, in response to the activity level of patient being a high activity level, increase the normal blood pressure range of patient 4 and / or the normal rate of blood pressure change of patient 4. Similarly, processing circuitry 50 may, in response to the activity level of patient being a low activity level, decrease the normal blood pressure range of patient 4 and / or the normal rate of blood pressure change of patient 4.

[0091] Processing circuitry 50 may determine the activity level of patient 4 via any suitable technique. For example, processing circuitry 50 may communicate with an external device, such as external device 12 or a wearable device (e.g., a fitness tracker or a smart watch) being worn by patient 4, that tracks the activity level of patient 4. Processing circuitry 50 may receive, from the external device, a signal indicative of the activity level of patient 4, and may, based on the activity level of patient 4, adjust the normal blood pressure range of patient 4 and / or the normal rate of blood pressure change of patient 4. In some examples, processing circuitry 50 may determine the activity level of patient 4 by receiving motion signals from accelerometer 65 or from an external device, and may determine, via any suitable technique, an activity level of patient 4 based on the motion signals.

[0092] In some examples, processing circuitry 50 may determine the posture of patient 4 and may adjust the normal blood pressure range of patient 4 and / or the normal rate of blood pressure change over a particular time period based on the posture of patient 4. Processing circuitry 50 may determine the posture of patient 4, such as whether patient 4 is lying down, whether patient 4 is sitting, whether patient 4 is standing up, and the like. If processing circuitry 50 determines that patient 4 is lying down, processing circuitry 50 may decrease the normal blood pressure range of patient 4 and / or the normal rate of blood pressure change of patient 4. Similarly, if processing circuitry 50 determines that patient 4 is standing, processing circuitry 50 may increase the normal blood pressure range of patient 4 and / or the normal rate of blood pressure change of patient 4.

[0093] Processing circuitry 50 may determine the posture of patient 4 via any suitable technique. For example, processing circuitry 50 may communicate with an external device, such as external device 12 or a wearable device (e.g., a fitness tracker or a smart watch) being worn by patient 4, that tracks the posture of patient 4. Processing circuitry 50 may receive, from the external device, a signal indicative of the posture of patient 4, andmay, based on the posture of patient 4, adjust the normal blood pressure range of patient 4 and / or the normal rate of blood pressure change of patient 4. In some examples, processing circuitry 50 may determine the posture of patient 4 by receiving motion signals from accelerometer 65 or from an external device, and may determine, via any suitable technique, the posture of patient 4 based on the motion signals.

[0094] In some examples, processing circuitry 50 may determine a medication schedule of patient 4 and may adjust the normal blood pressure range of patient 4 and / or the normal rate of blood pressure change over a particular time period based on the medication schedule of patient 4. When patient 4 takes certain medication, the medication may cause the blood pressure of patient 4 to increase or decrease. As such, processing circuitry 50 may increase or decrease the normal blood pressure range and / or the normal rate of blood pressure change over a particular time period.

[0095] For example, each time patient 4 takes a dose of medication, the patient 4 may interact with another device, such as external device 12, to provide input to indicate that patient 4 is taking a dose of medication, and the device may send a signal indicative of patient 4 taking the medication to IMD 10. Processing circuitry 50 may receive, from the device, the signal indicative of patient 4 is taking the medication, and may adjust the normal blood pressure range of patient 4 and / or the normal rate of blood pressure change over a particular time period.

[0096] In another example, processing circuitry 50 may be programmed with the specific time(s) of the day that patient 4 is scheduled to take a dose of medication. For example, if patient 4 takes a dose of medication at 8:00 AM and at 8:00 PM, processing circuitry 50 may be programmed with the specific times of 8:00AM and 8:00 PM. At the time(s) of the day where patient 4 is scheduled to take a dose of medication, processing circuitry 50 may adjust the normal blood pressure range of patient 4 and / or the normal rate of blood pressure change over a particular time period.

[0097] In some examples, processing circuitry 50 may compare the blood pressure of patient 4 and / or the rate of blood pressure change of patient 4 against the adjusted normal blood pressure range of patient 4 and / or the adjusted normal rate of blood pressure change for a specified time period after patient 4 has taken the medication, such as thirty minutes, an hour, and the like. After the specified time period, processing circuitry 50 may revert back to comparing the blood pressure of patient 4 and / or the rate of blood pressure changeof patient 4 against the unadjusted normal blood pressure range of patient 4 and / or the unadjusted normal rate of blood pressure change.

[0098] Processing circuitry 50 may receive any other information from an external device (e.g., external device 12, another device, or a remote system) that patient monitoring module 102 may use to adjust the normal blood pressure range of patient 4 and / or the normal rate of blood pressure change for patient 4. For example, processing circuitry 50 may receive hypertension metrics of patient 4, such as from blood work, urine analysis, and other labs, data from patient 4’s electronic medical records, physician notes regarding patient 4, patient notes by patient 4, and the like. Processing circuitry 50 may also receive additional physiological parameters of patient 4, such as heart sounds, ECGs, fluid retention status, and the like.

[0099] Processing circuitry 50 is configured to output the sensed physiological signals of patient 4 to external device 12. As described above, processing circuitry 50 may output an alert indicative of the blood pressure of patient being abnormal. In some examples, processing circuitry 50 may also continuously output the sensed physiological signals of patient 4 to one or more external devices, such as to external device 12 and / or a remote system. In some examples, processing circuitry 50 may output signals indicative of the blood pressure of patient 4, as determined by processing circuitry 50, to one or more external devices, such as to external device 12 and / or a remote system.

[0100] FIG. 4 is a block diagram illustrating an example configuration of external device 12, which, includes a smartphone, a laptop, a tablet computer, a personal digital assistant (PDA), a smartwatch, or any other suitable computing device. As shown in the example of FIG. 4, external device 12 may be logically divided into user space 70, kernel space 72, and hardware 74. Hardware 74 may include one or more hardware components that provide an operating environment for components executing in user space 70 and kernel space 72. User space 70 and kernel space 72 may represent different sections or segmentations of memory, where kernel space 72 provides higher privileges to processes and threads than user space 70. For instance, kernel space 72 may include operating system 76, which operates with higher privileges than components executing in user space 70.

[0101] As shown in FIG. 4, hardware 74 includes processing circuitry 78, memory 80, one or more input devices 82, one or more output devices 84, one or more sensors 86, andcommunication circuitry 88. Although shown in FIG. 4 as a stand-alone device for purposes of example, external device 12 may be any component or system that includes processing circuitry or other suitable computing environment for executing software instructions and, for example, need not necessarily include one or more elements shown in FIG. 4.

[0102] Processing circuitry 78 is configured to implement functionality and / or process instructions for execution within external device 12. For example, processing circuitry 78 may be configured to receive and process instructions stored in memory 80 that provide functionality of components included in kernel space 72 and user space 70 to perform one or more operations in accordance with techniques of this disclosure. Examples of processing circuitry 78 may include, any one or more microprocessors, controllers, GPUs, TPUs, DSPs, ASICs, FPGAs, or equivalent discrete or integrated logic circuitry.

[0103] Memory 80 may be configured to store information within external device 12, for processing during operation of external device 12. Memory 80, in some examples, is described as a computer-readable storage medium. In some examples, memory 80 includes a temporary memory or a volatile memory. Examples of volatile memories include RAM, DRAM, SRAM, and other forms of volatile memories known in the art. Memory 80, in some examples, also includes one or more memories configured for long-term storage of information, e.g., including non-volatile storage elements. Examples of such non-volatile storage elements include magnetic hard discs, optical discs, floppy discs, flash memories, or forms of electrically programmable memories (EPROM) or electrically erasable and programmable (EEPROM) memories. In some examples, memory 80 includes cloud- associated storage.

[0104] One or more input devices 82 of external device 12 may receive input, e.g., from a patient, a clinician, or another user. Examples of input are tactile, audio, kinetic, and optical input. Input devices 82 may include, as examples, a mouse, keyboard, voice responsive system, camera, buttons, control pad, microphone, presence-sensitive or touch- sensitive component (e.g., screen), or any other device for detecting input from a user or a machine.

[0105] One or more output devices 84 of external device 12 may generate output, e.g., to the patient or another user. Examples of output are tactile, haptic, audio, and visual output. Output devices 84 of external device 12 may include a presence-sensitive screen,sound card, video graphics adapter card, speaker, cathode ray tube (CRT) monitor, liquid crystal display (LCD), light emitting diodes (LEDs), or any type of device for generating tactile, audio, and / or visual output.

[0106] One or more sensors 86 may sense physiological parameters or physiological signals of patient 4. Sensor(s) 86 may include electrodes, accelerometers (e.g., 3-axis accelerometers), IMUs, gyroscopes, optical sensors, impedance sensors, temperature sensors, pressure sensors, heart sound sensors (e.g., microphones or accelerometers), and other sensors.

[0107] Communication circuitry 88 of external device 12 may communicate with other devices by transmitting and receiving data. Communication circuitry 88 may receive data from IMD 10, such as physiological signals (e.g., PPG signals) and / or physiological parameter values (e.g., blood pressure values), from communication circuitry 54 in IMD 10. Communication circuitry 88 may include a network interface card, such as an Ethernet card, an optical transceiver, a radio frequency transceiver, or any other type of device that can send and receive information. For example, communication circuitry 88 may include a radio transceiver configured for communication according to standards or protocols, such as 3G, 4G, 5G, WiFi (e.g., 802.11 or 802.15 ZigBee), Bluetooth®, or Bluetooth® Low Energy (BLE).

[0108] As shown in FIG. 4, processing circuitry 78 may execute health monitoring application 90 in user space 70 of external device 12. Health monitoring application 90 may be logically divided into presentation layer 92, application layer 94, and data layer 96. Presentation layer 92 may include a user interface (UI) component 98, which generates and renders user interfaces of health monitoring application 90. Data layer 96 may include patient data 100, which may be received from IMD 10 via communication circuitry 88 and stored in memory 80 by processing circuitry 78, or may be determined by processing circuitry 78 and stored in memory 80.

[0109] Application layer 94 may include, but is not limited to, a patient monitoring module 102. In some examples, patient monitoring module 102 may receive, from IMD 10, physiological signals (e.g., PPG signals) and / or physiological parameter values (e.g., blood pressure values), as determined by IMD 10. Patient monitoring module 102 may, in response, store data received from IMD 10 and / or data derived from IMD 10, such as the blood pressure of patient 4, as patient data 100. In some examples, patient monitoringmodule 102 may send, via communication circuitry 88, an indication of the one or more physiological parameter values of patient 4 to a remote system.

[0110] In some examples, patient monitoring module 102 may continuously receive, from IMD 10, optical signals sensed by IMD 10, and patient monitoring module 102 may determine, based on an optical signal sensed by IMD 10 and using any suitable technique, the blood pressure of patient 4.[oni] Patient monitoring module 102 may implement any of the techniques described herein, such as described with respect to IMD 10, to determine that the blood pressure of patient 4 is abnormal and to output an alert indicative of the blood pressure of patient 4 being abnormal. For example, patient monitoring module 102 may continuously receive, from IMD 10, optical signals sensed by IMD 10, such as PPG signals, and may periodically determine, based on the optical signals, the blood pressure of patient 4 as well as the rate of change in the blood pressure of patient 4 over time.

[0112] Patient monitoring module 102 may use a blood pressure measurement algorithm to determine, based on the optical signals received from IMD 10, the blood pressure of patient 4. Patient monitoring module 102 may calibrate the blood pressure measurement algorithm based on an independent blood pressure reading from an independent calibration source, such as a cuff blood pressure monitor.

[0113] Patient monitoring module 102 may calibrate the blood pressure measurement algorithm such that the blood pressure of patient 4 determined using the blood pressure measurement algorithm matches the independent blood pressure reading from the independent calibration source. In addition or alternatively, patient monitoring module 102 may calibrate blood pressure measurement algorithm so that blood pressure measurement algorithm is able to determine relative changes to blood pressure that matches to relative changes to the blood pressure that is determined by the independent calibration source. That is, if the independent calibration source determines independent blood pressure readings at two different points in time that changes by a specific millimeters Mercury (mmHg) or by a specific percentage (e.g., 20%), patient monitoring module 102 may calibrate the blood pressure measurement algorithm to determine blood pressures of patient 4 at the same two different points in time that also change by the same specific mmHg or by the same specific percentage.

[0114] Patient monitoring module 102 may determine the blood pressure of patient 4according to a specific frequency, schedule, and / or cadence. Patient monitoring module 102 may more frequently determine the blood pressure of patient 4 based on the optical signals during an initial period after patient 4 undergoes a surgical operation, such as the first two weeks post-surgery. For example, patient monitoring module 102 may very frequently determine the blood pressure of patient 4 during an initial post-surgery period, such as every hour, every two hours, every 4 hours, and the like.

[0115] Patient monitoring module 102 may, after the initial period after the surgical operation, taper the frequency at which patient monitoring module 102 determines the blood pressure of patient 4 over time. For example, after the initial post-surgery period, patient monitoring module 102 may gradually reduce the frequency at which patient monitoring module 102 determines the blood pressure of patient 4 over time, such that, after a specified amount of time, such as thirty days post-surgery, patient monitoring module 102 may determine the blood pressure of patient 4 once a day.

[0116] Patient monitoring module 102 may also be programmed to determine the blood pressure of patient 4 according to specified schedules and / or at specified frequencies. For example, a doctor for patient 4 may interact with input device(s) 82, to input a specific schedule and / or frequency for determining the blood pressure of patient 4, and patient monitoring module 102 may determine the blood pressure of patient 4 according to the inputted schedule and / or at the inputted frequency. For example, if patient monitoring module 102 determines that the blood pressure of patient 4 is in a hypertensive range, patient monitoring module 102 may increase the frequency at which patient monitoring module 102 determines the blood pressure of patient 4. When patient monitoring module 102 determines that the blood pressure of patient 4 is below the hypertensive range, patient monitoring module 102 may lower the frequency at which patient monitoring module 102 determines the blood pressure of patient 4.

[0117] In some examples, patient monitoring module 102 may adjust the schedule and / or frequency for determining the blood pressure of patient 4 based on any other suitable factors, such as the physiological condition of patient 4 and / or other external factors. In some examples, patient monitoring module 102 may determine an activity level of patient 4 and may, in response to determining that the activity level of patient 4 corresponds to patient 4 being physically active (e.g., walking, running, etc.), determine the blood pressure of patient 4 to determine whether the blood pressure of patient 4 isabnormal while patient 4 is being physically active. Patient monitoring module 102 may determine the activity level of patient 4 via any suitable technique. For example, patient monitoring module 102 may communicate with another device, such as a wearable device (e.g., a fitness tracker or a smart watch) being worn by patient 4, that tracks the activity level of patient 4, and may receive, from the external device, a signal indicative of the activity level of patient 4. In some examples, patient monitoring module 102 may determine the activity level of patient 4 by receiving motion signals from an accelerometer of sensor(s) 86, and may determine, via any suitable technique, an activity level of patient 4 based on the motion signals.

[0118] Patient monitoring module 102 may receive any other information from an external device (e.g., external device 12, another device, or a remote system) that patient monitoring module 102 may use to adjust the schedule, frequency, and / or cadence at which patient monitoring module 102 determines the blood pressure of patient 4. For example, patient monitoring module 102 may receive hypertension metrics of patient 4, such as from blood work, urine analysis, and other labs, data from patient 4’s electronic medical records, physician notes regarding patient 4, patient notes by patient 4, and the like. Patient monitoring module 102 may also receive additional physiological parameters of patient 4, such as heart sounds, ECGs, fluid retention status, and the like.

[0119] In some examples, patient monitoring module 102 may determine that patient 4 has undergone surgery and may, in response to determining that patient 4 has undergone the surgery, start determining blood pressure of patient 4 according to the specified schedule, frequency, and / or cadence. That is, patient monitoring module 102 may not start periodically determining the blood pressure of patient 4 until patient monitoring module 102 has determined that patient 4 has undergone the surgery and the surgery has been completed. For example, patient monitoring module 102 may receive, from a remote system, a signal indicative of patient 4 having undergone surgery. Patient monitoring module 102 may, in response to receiving the signal indicative of patient 4 having undergone the surgery, start determining the blood pressure of patient 4 according to the specified schedule, frequency, and / or cadence.

[0120] In some examples, input device(s) 82 may receive user input indicative of patient 4 having undergone surgery. That is, a user, such as patient 4, a clinician, and the like may interact with input device(s) 82 to provide user input to indicate that patient 4 hasundergone the surgery. Patient monitoring module 102 may, in response to input device(s) 82 receiving user input indicative of patient 4 having undergone the surgery, start determining the blood pressure of patient 4 according to the specified schedule, frequency, and / or cadence.

[0121] Patient monitoring module 102 may monitor the blood pressure of patient 4 and may, based on the blood pressure of patient 4, output an alert. Such an alert may be in the form of an audible alert (e.g., a sound), a haptic alert (e.g., vibrations), or a notification that is sent to another device or system (e.g., to a remote system). For example, if patient monitoring module 102 includes a speaker device in output device(s) 84, patient monitoring module 102 may cause the speaker device to output an audible alert (e.g., a sound). In some examples, if output device(s) 84 includes a display device, patient monitoring module 102 may output a notification indicative of the blood pressure of patient 4 at the display device. In another example, patient monitoring module 102 may output the alert in the form of a notification to another device, such as a remote system, displaying a notification indicative of the blood pressure of patient 4.

[0122] In some examples, patient monitoring module 102 may determine whether the blood pressure of patient 4 is abnormal. Patient monitoring module 102 may, in response to determining that the blood pressure of patient 4 is abnormal, output an alert indicative of the blood pressure of patient 4 is abnormal. Patient monitoring module 102 may be programmed with or may otherwise determine a normal blood pressure range for patient 4. For example, patient monitoring module 102 may be programmed with or may determine one or more thresholds, such as a high threshold and / or a low threshold. Patient monitoring module 102 may, in response to determining that the blood pressure of patient 4 is outside the normal blood pressure range, output an alert indicative of the blood pressure of patient 4 being abnormal.

[0123] In some examples, patient monitoring module 102 may determine a normal blood pressure range of patient 4 based on determining a baseline blood pressure of patient 4 prior to patient 4’s surgery. For example, patient monitoring module 102 may determine the average baseline blood pressure level of patient 4 over a particular period of time. Patient monitoring module 102 may determine the normal blood pressure range to have a high threshold that is a specified mmHg above the average baseline blood pressure level, or may determine the normal blood pressure range to have a high threshold that is aspecified percentage above the average baseline blood pressure level. Similarly, patient monitoring module 102 may determine the normal blood pressure range to have a low threshold that is a specified mmHg below the average blood pressure level, or may determine the normal blood pressure range to have a low threshold that is a specified percentage below the average baseline blood pressure level.

[0124] In some examples, patient monitoring module 102 may determine a normal blood pressure range of patient 4 that changes over time. For example, if the blood pressure of patient 4 normally rise by a specific slope over time post-surgery, patient monitoring module 102 may also determine a normal blood pressure range of patient 4 that rises according to the specific slope over time. That is, patient monitoring module 102 may determine an initial normal blood pressure range and may determine a slope by which the high threshold and the low threshold of the normal blood pressure range rises over time. If patient monitoring module 102 determines that the blood pressure of patient 4 rises by more than the specific slope, such that the blood pressure of patient 4 is not within the determined normal blood pressure range, patient monitoring module 102 may determine that the blood pressure of patient 4 is abnormal.

[0125] In some examples, patient monitoring module 102 may determine a normal rate of blood pressure change over a particular time period. Patient monitoring module 102 may determine a rate of change in the blood pressure of patient 4 and may compare the rate of change in the blood pressure of patient 4 over a particular time period to the normal rate of blood pressure change over the particular time period to determine whether the blood pressure of patient 4 is abnormal. For example, patient monitoring module 102 may determine whether the rate at which the blood pressure of patient 4 has increased over the particular time period is greater than a normal rate of blood pressure increase over the particular time period. Patient monitoring module 102 may, responsive to determining that the rate at which the blood pressure of patient 4 has increased over the particular time period is greater than the normal rate of blood pressure increase over the particular time period, determine that the blood pressure of patient 4 is abnormal.

[0126] In some examples, patient monitoring module 102 may dynamically adjust the normal blood pressure range of patient 4 and / or the normal rate of blood pressure change over a particular time period based on factors such as time, the activity level of patient 4, the posture of patient 4, or other factors. The blood pressure of a patient may increasewhile the patient is highly active and may decrease when the patient is relatively less active. As such, patient monitoring module 102 may increase the normal blood pressure range of patient 4 and / or the normal rate of blood pressure change of patient 4 when patient monitoring module 102 detects that the activity level of patient 4 is high, and / or may decrease the normal blood pressure range of patient 4 and / or the normal rate of blood pressure change of patient 4 when patient monitoring module 102 detects that the activity level of patient 4 is low.

[0127] For example, patient monitoring module 102 may determine the activity level of patient 4 as low, normal, or high, where a low activity level may denote that patient 4 is completely at rest (e.g., sleeping or sitting still), and where a high activity level may denote that patient 4 is physically exerting themselves (e.g., walking, running, lifting weights, etc.). Patient monitoring module 102 may receive, from the external device an indication of the activity level of patient 4. Patient monitoring module 102 may, in response to the activity level of patient being a high activity level, increase the normal blood pressure range of patient 4 and / or the normal rate of blood pressure change of patient 4. Similarly, patient monitoring module 102 may, in response to the activity level of patient being a low activity level, decrease the normal blood pressure range of patient 4 and / or the normal rate of blood pressure change of patient 4.

[0128] Patient monitoring module 102 may determine the activity level of patient 4 via any suitable technique. For example, patient monitoring module 102 may communicate with a wearable device (e.g., a fitness tracker or a smart watch) being worn by patient 4, that tracks the activity level of patient 4. Patient monitoring module 102 may receive, from the external device, a signal indicative of the activity level of patient 4, and may, based on the activity level of patient 4, adjust the normal blood pressure range of patient 4 and / or the normal rate of blood pressure change of patient 4. In some examples, patient monitoring module 102 may determine the activity level of patient 4 by receiving motion signals from an accelerometer of sensor(s) 86, and may determine, via any suitable technique, an activity level of patient 4 based on the motion signals.

[0129] In some examples, patient monitoring module 102 may determine the posture of patient 4 and may adjust the normal blood pressure range of patient 4 and / or the normal rate of blood pressure change over a particular time period based on the posture of patient 4. Patient monitoring module 102 may determine the posture of patient 4, such as whetherpatient 4 is lying down, whether patient 4 is sitting, whether patient 4 is standing up, and the like. If patient monitoring module 102 determines that patient 4 is lying down patient monitoring module 102 may decrease the normal blood pressure range of patient 4 and / or the normal rate of blood pressure change of patient 4. Similarly, if patient monitoring module 102 determines that patient 4 is standing, patient monitoring module 102 may increase the normal blood pressure range of patient 4 and / or the normal rate of blood pressure change of patient 4.

[0130] Patient monitoring module 102 may determine the posture of patient 4 via any suitable technique. For example, patient monitoring module 102 may communicate with a wearable device (e.g., a fitness tracker or a smart watch) being worn by patient 4, that tracks the posture of patient 4. Patient monitoring module 102 may receive, from the external device, a signal indicative of the posture of patient 4, and may, based on the posture of patient 4, adjust the normal blood pressure range of patient 4 and / or the normal rate of blood pressure change of patient 4. In some examples, patient monitoring module 102 may determine the posture of patient 4 by receiving motion signals from an accelerometer of sensor(s) 86, and may determine, via any suitable technique, the posture of patient 4 based on the motion signals.

[0131] In some examples, patient monitoring module 102 may determine a medication schedule of patient 4 and may adjust the normal blood pressure range of patient 4 and / or the normal rate of blood pressure change over a particular time period based on the medication schedule of patient 4. When patient 4 takes certain medication, the medication may cause the blood pressure of patient 4 to increase or decrease. As such, patient monitoring module 102 may increase or decrease the normal blood pressure range and / or the normal rate of blood pressure change over a particular time period.

[0132] For example, each time patient 4 takes a dose of medication, the patient 4 may interact with external device 12 via input device(s) 82 to provide input that indicates patient 4 is taking a dose of medication. Patient monitoring module 102 may, based on the input indicative of patient 4 is taking the medication, adjust the normal blood pressure range of patient 4 and / or the normal rate of blood pressure change over a particular time period.

[0133] In another example, patient monitoring module 102 may be programmed with the specific time(s) of the day that patient 4 is scheduled to take a dose of medication. Forexample, if patient 4 takes a dose of medication at 8:00 AM and at 8:00 PM, patient monitoring module 102 may be programmed with the specific times of 8:00AM and 8:00 PM. At the time(s) of the day where patient 4 is scheduled to take a dose of medication, patient monitoring module 102 may adjust the normal blood pressure range of patient 4 and / or the normal rate of blood pressure change over a particular time period.

[0134] In some examples, patient monitoring module 102 may compare the blood pressure of patient 4 and / or the rate of blood pressure change of patient 4 against the adjusted normal blood pressure range of patient 4 and / or the adjusted normal rate of blood pressure change for a specified time period after patient 4 has taken the medication, such as thirty minutes, an hour, and the like. After the specified time period, patient monitoring module 102 may revert back to comparing the blood pressure of patient 4 and / or the rate of blood pressure change of patient 4 against the unadjusted normal blood pressure range of patient 4 and / or the unadjusted normal rate of blood pressure change.

[0135] Patient monitoring module 102 may receive any other information from an external device (e.g., external device 12, another device, or a remote system) that patient monitoring module 102 may use to adjust the normal blood pressure range of patient 4 and / or the normal rate of blood pressure change for patient 4. For example, patient monitoring module 102 may receive hypertension metrics of patient 4, such as from blood work, urine analysis, and other labs, data from patient 4’s electronic medical records, physician notes regarding patient 4, patient notes by patient 4, and the like. Patient monitoring module 102 may also receive additional physiological parameters of patient 4, such as heart sounds, ECGs, fluid retention status, and the like.

[0136] External device 12 may be configured to output the sensed physiological signals of patient 4 to a remote system. As described above, patient monitoring module 102 may output, via output device(s) 84, an alert indicative of the blood pressure of patient being abnormal. In some examples, patient monitoring module 102 may also continuously output the sensed physiological signals of patient 4 to one or more other devices and / or to a remote system.

[0137] In some examples, patient monitoring module 102 may cause UI component to output, for display at a display device of output device(s) 84, a dashboard that enables users such as patient 4, clinicians, patient 4’s family members, and the like to view and monitor the physiological parameters of patient 4. The dashboard may present details ofthe physiological parameters of patient 4, such as the blood pressure of patient 4 over time, enabling users to view how the physiological parameters of patient 4 are trending over time. Such a dashboard may be useful for tracking patient 4’s recovery after invasive surgery.

[0138] In some examples, the dashboard may present the blood pressure of patient 4, as determined by IMD 10 and / or external device 12 over time, such as in the form of a graph of the blood pressure of patient 4 over time. The graph may plot various other information regarding patient 4, such as the activity level of patient 4 over time, the posture of patient 4 over time, the specific times when patient 4 took doses of medication, times where patient 4 felt pain, the amount of pain felt by patient 4 over time, water retention levels of patient 4 over time, the heart rate of patient 4 over time against the high and low thresholds of the normal range of blood pressure over time, the rate of change in the heart rate of patient 4 over time against a normal rate of change of blood pressure over time, the ECG of patient 4 over time, heart sounds of patient 4 over time, the oxygen saturation (SpO2) of patient 4 over time, the tissue oxygen saturation (StO2) of patient 4 over time, the bioelectrical impedance of patient 4, or any other information that may be helpful for clinicians and other users to track patient 4’s recovery after surgery. The graph may also present additional information such as any data from patient 4’s electronic medical records, patient 4’s lab results such as blood work, urine analysis, and the like, patient 4’s schedule of physical therapy, physician’s notes, patient notes, symptom markings, and / or family / caregiver / social circle inputs (e.g., encouragement, data points, etc.).

[0139] FIG. 5 is a block diagram illustrating an operating perspective of a health monitoring system 116 (“HMS 116”). HMS 116 may be implemented in a computing system 110, which may include hardware components such as processing circuitry 112, memory 114, and communication circuitry, embodied in one or more physical devices. FIG. 5 provides an operating perspective of HMS 116 when hosted as a cloud-based platform. In the example of FIG. 5, components of HMS 116 are arranged according to multiple logical layers that implement the techniques of this disclosure. Each layer may be implemented by one or more modules comprised of hardware, software, or a combination of hardware and software.

[0140] Computing devices, such as external device 12, operate as clients that communicate with HMS 116 via interface layer 120. The computing devices typically execute client software applications, such as desktop application(s), mobile application(s), and web application(s). Interface layer 120 represents a set of application programming interfaces (API) or protocol interfaces presented and supported by HMS 116 for the client software applications. Interface layer 120 may be implemented with one or more web servers.

[0141] As shown in FIG. 5, HMS 116 also includes an application layer 122 that represents a collection of services 126 for implementing the functionality ascribed to HMS 116 herein. Processing circuitry of HMS 116 may execute application layer 122 receives information from IMD 10 and / or from client applications, e.g., data from external device 12, some or all of which may have been received from IMD 10, and further processes the information according to one or more of services 126. Application layer 122 may be implemented as one or more discrete software services 126 executed on one or more application server, e.g., physical or virtual machines. That is, the application servers provide runtime environments for execution of services 126. In some examples, the functionality of interface layer 120 as described above and the functionality of application layer 122 may be implemented at the same server.

[0142] One or more storage devices of HMS 116 may implement data layer 124 of HMS 116. Data layer 124 provides persistence for information in HMS 116 using one or more data repositories 128. A data repository 128, generally, may be any data structure or software that stores and / or manages data. Examples of one or more data repositories 128 include, but are not limited to relational databases, multi-dimensional databases, maps, and / or hash tables.

[0143] Software services 126 of application layer 122 includes patient monitoring service 130. In some examples, patient monitoring service 130 may receive, from IMD 10 and / or from external device 12, the blood pressure of patient 4 over time, as determined by IMD 10 and / or external device 12. Patient monitoring service 130 may, in response, store the blood pressure data of patient 4 into one or more data repositories 128 as patient data 142. In some examples, patient monitoring service 130 may cause HMS 116 to output a notification (e.g., to clinician computing devices, external device 12, and / or to othercomputing devices and / or systems connected to HMS 116 via a network) that includes an indication of blood pressure readings of patient 4.

[0144] Patient monitoring service 130 may also receive any other data associated with patient 4 from other devices and / or systems, and may store such received data as patient data 142. For example, patient monitoring service 130 may receive motion data indicative of patient 4’s activity level and / or posture, patient 4’s medication schedule, data from patient 4’s electronic medical records, patient 4’s lab results such as blood work, urine analysis, and the like, data regarding patient 4’s fluid retention, patient 4’s ECGs, patient 4’s schedule of physical therapy, physician’s notes, patient notes, symptom markings, and / or family / caregiver / social circle inputs (e.g., encouragement, data points, etc.).

[0145] In some examples, patient monitoring service 130 may implement any of the techniques described herein to determine the blood pressure of patient 4. For example, HMS 116 may receive, from external device 12 and / or IMD 10, optical signals captured by IMD 10, such as PPG signals. Patient monitoring service 130 may perform any of the techniques performed by processing circuitry 50 of FIG. 3, as described in this disclosure, to determine the blood pressure of patient 4. Patient monitoring service 130 may store such blood pressure data into one or more data repositories 128 as patient data 142. In some examples, patient monitoring service 130 may cause HMS 116 to output a notification (e.g., to clinician computing devices, external device 12, and / or to other computing devices and / or systems connected to HMS 116 via a network) that includes an indication of the physical parameters of patient 4.

[0146] In some examples, patient monitoring service 130 may cause UI component to output, for display at a display device of, a dashboard that enables users such as patient 4, clinicians, patient 4’s family members, and the like to view and monitor the physiological parameters of patient 4. The dashboard may present details of the physiological parameters of patient 4, such as the blood pressure of patient 4 over time, enabling users to view how the physiological parameters of patient 4 are trending over time. Such a dashboard may be useful for tracking patient 4’s recovery after invasive surgery.

[0147] In some examples, the dashboard may present the blood pressure of patient 4, as determined by IMD 10 and / or external device 12 over time, such as in the form of a graph of the blood pressure of patient 4 over time. The graph may plot various other information regarding patient 4, such as the activity level of patient 4 over time, theposture of patient 4 over time, the specific times when patient 4 took doses of medication, times where patient 4 felt pain, the amount of pain felt by patient 4 over time, water retention levels of patient 4 over time, the heart rate of patient 4 over time against the high and low thresholds of the normal range of blood pressure over time, the rate of change in the heart rate of patient 4 over time against a normal rate of change of blood pressure over time, the ECG of patient 4 over time, heart sounds of patient 4 over time, the oxygen saturation (SpO2) of patient 4 over time, the tissue oxygen saturation (StO2) of patient 4 over time, the bioelectrical impedance of patient 4, or any other information that may be helpful for clinicians and other users to track patient 4’s recovery after surgery. The graph may also present additional information such as any data from patient 4’s electronic medical records, patient 4’s lab results such as blood work, urine analysis, and the like, patient 4’s schedule of physical therapy, physician’s notes, patient notes, symptom markings, and / or family / caregiver / social circle inputs (e.g., encouragement, data points, etc.).

[0148] FIG. 6 is a block diagram illustrating an example system that includes a local device 150, a network 152, external computing devices, such as a server 154, and one or more other computing devices 160A-160N (collectively, "computing devices 160"), which may be coupled to IMD 10 and local device 150 via network 152, in accordance with one or more techniques described herein. In this example, IMD 10 may use communication circuitry 54 to communicate with local device 150 via a wireless connection. In the example of FIG. 6, local device 150, external device 12, server 154, and computing devices 160 are interconnected and may communicate with each other through network 152. In some examples, external device 12 is an example of local device 150.

[0149] Local device 150 may be external device 12, in some examples. Local device 150 may include a device that connects to network 152 via any of a variety of connections, such as telephone dial-up, digital subscriber line (DSL), or cable modem connections. In other examples, local device 150 may be coupled to network 152 through different forms of connections, including wired or wireless connections. In some examples, local device 150 may be a user device, such as a tablet or smartphone, that may be co-located with patient 4. IMD 10 may be configured to transmit data, such as patient data, to local device 150. Local device 150 may then communicate the retrieved data to server 154 via network 152.

[0150] In some cases, server 154 may be configured to provide a secure storage site for data that has been collected from IMD 10 and / or external device 12. In some cases, server 154 may assemble data in web pages or other documents for viewing by trained professionals, such as clinicians, via computing devices 160. One or more aspects of the illustrated system of FIG. 6 may be implemented with general network technology and functionality, which may be similar to that provided by the Medtronic CareLink® Network. In some examples, server 154 may implement HMS 116 shown in FIG. 5.

[0151] In some examples, one or more of computing devices 160 may be a tablet or other smart device located with a clinician, by which the clinician may program, receive alerts from, and / or interrogate IMD 10. For example, the clinician may access patient data and / or indications of patient health collected by IMD 10 through a computing device of computing devices 160, such as when patient 4 is 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 patient 4 into an application executed by one of computing devices 160, such as based on a status of a patient condition determined by IMD 10, external device 12, server 154, or any combination thereof, or based on other patient data known to the clinician. One of computing devices 160 then may transmit the instructions for medical intervention to another of computing devices 160 located with patient 4 or a caregiver of patient 4. 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, one of computing devices 160 may generate an alert to patient 4 based on a status of a medical condition of patient 4, which may enable patient 4 proactively to seek medical attention prior to receiving instructions for a medical intervention. In this manner, patient 4 may be empowered to take action, as needed, to address his or her medical status, which may help improve clinical outcomes for patient 4.

[0152] In the example illustrated by FIG. 6, server 154 includes a storage device 156, e.g., to store data retrieved from IMD 10, and processing circuitry 158. Although not illustrated in FIG. 6 computing devices 160 may similarly include a storage device and processing circuitry.

[0153] Storage device 156 may include a computer-readable storage medium or computer-readable storage device. In some examples, storage device 156 includes one ormore of a short-term memory or a long-term memory. Storage device 156 may include, for example, RAM, DRAM, SRAM, magnetic discs, optical discs, flash memories, or forms of EPROM or EEPROM. In some examples, storage device 156 is used to store data indicative of instructions for execution by processing circuitry 158.

[0154] Processing circuitry 158 may include one or more processors that are configured to implement functionality and / or process instructions for execution within server 154. For example, processing circuitry 158 may be capable of processing instructions stored in storage device 156. Processing circuitry 158 may 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 circuitry 158 may include any suitable structure, whether in hardware, software, firmware, or any combination thereof, to perform the functions ascribed herein to processing circuitry 158.

[0155] Processing circuitry 158 of server 154 and / or the processing circuity of computing devices 160 may implement any of the techniques described herein to determine one or more physiological parameters of patient 4. For example, server 154 and / or any one of computing devices 160 may receive, from external device 12, an optical signals captured by IMD 10. Processing circuitry 158 and / or the processing circuity of computing devices 160 may perform any of the techniques performed by processing circuitry 50 of FIG. 4, as described in this disclosure, to determine one or more physiological parameters of patient 4, such as the blood pressure of patient 4.

[0156] Processing circuitry 158 of server 154 and / or the processing circuity of computing devices 160 may output an indication of the one or more physiological parameters of patient 4. For example, server 154 may transmit, to one or more of computing devices 160, a signal indicative of one or more physiological parameters of patient 4. In another example, one of computing devices 160 may transmit, to another one of computing devices 160, a signal indicative of one or more physiological parameters of patient 4.

[0157] In some examples, one of computing devices 160 may output a graphical user interface that includes information regarding the one or more physiological parameters of patient 4, such as the dashboards described with respect to FIGS. 4 and 5. One or more computing devices 160 may a dashboard that enables users such as patient 4, clinicians,patient 4’s family members, and the like to view and monitor the physiological parameters of patient 4. The dashboard may present details of the physiological parameters of patient 4, such as the blood pressure of patient 4 over time, enabling users to view how the physiological parameters of patient 4 are trending over time. Such a dashboard may be useful for tracking patient 4’s recovery after invasive surgery.

[0158] In some examples, the dashboard may present the blood pressure of patient 4, as determined by IMD 10 and / or external device 12 over time, such as in the form of a graph of the blood pressure of patient 4 over time. The graph may plot various other information regarding patient 4, such as the activity level of patient 4 over time, the posture of patient 4 over time, the specific times when patient 4 took doses of medication, times where patient 4 felt pain, the amount of pain felt by patient 4 over time, water retention levels of patient 4 over time, the heart rate of patient 4 over time against the high and low thresholds of the normal range of blood pressure over time, the rate of change in the heart rate of patient 4 over time against a normal rate of change of blood pressure over time, the ECG of patient 4 over time, heart sounds of patient 4 over time, the oxygen saturation (SpO2) of patient 4 over time, the tissue oxygen saturation (StO2) of patient 4 over time, the bioelectrical impedance of patient 4, or any other information that may be helpful for clinicians and other users to track patient 4’s recovery after surgery. The graph may also present additional information such as any data from patient 4’s electronic medical records, patient 4’s lab results such as blood work, urine analysis, and the like, patient 4’s schedule of physical therapy, physician’s notes, patient notes, symptom markings, and / or family / caregiver / social circle inputs (e.g., encouragement, data points, etc.).

[0159] FIG. 7 is a flow diagram illustrating an example technique according to the present disclosure. FIG. 7 is described with respect to FIGS. 3 and 4.

[0160] As shown in FIG. 7, IMD 10 may be implanted in patient 4 prior to patient 4 undergoing surgery (702). After IMD 10 is implanted in patient 4, IMD 10 and / or external device 12 may calibrate the blood pressure measurements made by IMD 10 and / or external device 12 using an independent blood pressure reading from an independent calibration source (704). IMD 10 and / 2 external device 12 may also determine baseline blood pressure readings for patient 4 prior to surgery (706).

[0161] Patient 4 may therefore undergo surgery (708). Post-surgery, IMD 10 and / or external device 12 may determine a schedule, frequency, and / or cadence of determining the blood pressure of patient 4 as well as determining a normal blood pressure range and / or a normal rate of blood pressure change for patient 4 (710). IMD 10 and / or external device 12 may determine the blood pressure of patient 4 and / or the rate of blood pressure change of patient 4 according to the determined schedule (712). For example, IMD 10 and / or external device 12 may determine that patient 4 has undergone the surgery and may, in response, determine the blood pressure of patient 4.

[0162] As IMD 10 and / or external device 12 determines the blood pressure of patient 4 and / or the rate of blood pressure change of patient 4, IMD 10 and / or external device 12 may, in response to determining that the blood pressure of patient 4 is abnormal, output an alert indicative of the blood pressure of patient 4 being abnormal (716). IMD and / or external device 12 may determine that the blood pressure of patient 4 is abnormal if the blood pressure of patient 4 is outside the normal blood pressure range for patient 4 or if the rate of blood pressure change of patient 4 is greater than the normal rate of blood pressure change for patient 4.

[0163] As IMD 10 and / or external device 12 determines the blood pressure of patient 4 and / or the rate of blood pressure change of patient 4, IMD 10 and / or external device 12 may also adjust the normal blood pressure range for patient 4 and / or the normal rate of blood pressure change for patient 4 (714). For example, IMD 10 and / or external device 12 may adjust the normal blood pressure range for patient 4 and / or the normal rate of blood pressure change for patient 4 based on factors such as the activity level and / or posture of patient 4, the medication schedule of patient 4, or any other suitable conditions, as described throughout this disclosure.

[0164] FIG. 8 is a flow diagram that illustrates performing an example technique according to this disclosure. Although primarily described with respect to IMD 10 and external device 12, it should be understood that the techniques of this disclosure may be applied to any medical device described herein.

[0165] As shown in FIG. 8, one or more sensors 62 of an implantable medical device 10 for implantation within a patient 4 may sense an optical signal (802). In some examples, the optical signal may comprise a photoplethysmographic (PPG) signal.

[0166] Processing circuitry 50 of the implantable medical device 10 or processingcircuitry 78 of external device 12 may determine a blood pressure of the patient 4 based on the optical signal sensed after the patient 4 undergoes an invasive surgery (804). In some examples, processing circuitry 50 or 78 may determine that the patient 4 has undergone the invasive surgery and may, in response to determining that the patient 4 has undergone the invasive surgery, determine the blood pressure of the patient 4 based on the optical signal sensed after the patient 4 undergoes the invasive surgery.

[0167] In some examples, to determine the blood pressure of the patient, the processing circuitry 50 or 78 may determine, based on optical signals sensed by the one or more sensors 62, blood pressure levels of the patient 4 according a schedule, where the schedule specifies a frequency of determining the blood pressure levels of the patient 4 during an initial time period after the patient undergoes the invasive surgery, and wherein the schedule tapers the frequency of determining the blood pressure levels of the patient 4 over time after the initial time period.

[0168] In some examples, processing circuitry 50 or 78 may receive independent blood pressure readings from an independent calibration source and may calibrate a blood pressure measurement algorithm used to determine the blood pressure of the patient 4 based on the independent blood pressure readings. In some examples, the independent blood pressure readings specify first relative changes to blood pressure levels of the patient 4, and to calibrate the blood pressure measurement algorithm used to determine the blood pressure of the patient 4 based on the independent blood pressure readings, processing circuitry 50 or 78 may calibrate the blood pressure measurement algorithm to determine, based on optical signals sensed by the one or more sensors, second relative changes to blood pressure levels of the patient that matches the first relative changes to the blood pressure levels of the patient specified by the independent blood pressure readings.

[0169] Processing circuitry 50 or 78 may determine, based on a normal blood pressure range or a normal rate of blood pressure change over a particular period of time, that the blood pressure of the patient 4 is abnormal (806). In some examples, to determine that the blood pressure of the patient is abnormal, the processing circuitry 50 or 78 may determine, based on the blood pressure of the patient, that a rate of blood pressure change over the particular period of time is greater than normal rate of blood pressure change over the particular period of time. Processing circuitry 50 or 78 may, in response to determining that the rate of blood pressure change over the particular period of time is greater thannormal rate of blood pressure change over the particular period of time, determine that the blood pressure of the patient 4 is abnormal.

[0170] In some examples, to determine that the blood pressure of the patient is abnormal, the processing circuitry 50 or 78 may determine that the blood pressure of the patient 4 is outside the normal blood pressure range. Processing circuitry 50 or 78 may, in response to determining that the blood pressure of the patient 4 is outside the normal blood pressure range, determine that the blood pressure of the patient 4 is abnormal. In some examples, processing circuitry 50 or 78 may decrease the normal blood pressure range over time after the patient 4 undergoes invasive surgery.

[0171] In some examples, processing circuitry 50 or 78 may determine an activity level of the patient 4 and may adjust the normal blood pressure range based on the activity level of the patient 4. In some examples, to determine the activity level of the patient 4, processing circuitry 50 or 78 may obtain, from a computing device that senses motion of the patient 4, a signal indicative of the activity level of the patient 4, and may determine, based on the signal indicative of the activity level of the patient 4, the activity level of the patient 4. In some examples, to determine the activity level of the patient 4, processing circuitry 50 or 78 may obtain, from the one or more sensors 62, a signal indicative of a motion of the implantable medical device 10, and may determine, based on the signal indicative of the motion of the implantable medical device 10, the activity level of the patient 4.

[0172] In some examples, to adjust the normal blood pressure range based on the activity level of the patient 4, the processing circuitry 50 or 78 may, based on determining that the activity level of the patient 4 is low, decrease a high threshold of the normal blood pressure range. In some examples, to adjust the normal blood pressure range based on the activity level of the patient 4, the processing circuitry 50 or 78 may, based on determining that the activity level of the patient 4 is high, increase a high threshold of the normal blood pressure range.

[0173] In some examples, the processing circuitry 50 or 78 may determine a posture of the patient 4 and may adjust the normal blood pressure range based on the posture of the patient 4. In some examples, to adjust the normal blood pressure range based on the posture of the patient 4, the processing circuitry 50 or 78 may determine that the patient 4 is lying down and may, based on determining that the patient 4 is lying down, decrease ahigh threshold of the normal blood pressure range.

[0174] In some examples, the implantable medical device 10 is implanted in the patient 4 prior to the patient 4 undergoing the invasive surgery. The one or more sensors 62 may, prior to the patient 4 undergoing the invasive surgery, sense one or more baseline optical signals. Processing circuitry 50 or 78 may determine, based on the one or more baseline optical signals, a baseline blood pressure range for the patient 4. In some examples, processing circuitry 50 or 78 may determine the normal blood pressure range based on the baseline blood pressure range for the patient 4.

[0175] In some examples, processing circuitry 50 or 78 may determine a medication schedule of the patient 4 and may adjust the normal blood pressure range based on the medication schedule of the patient 4.

[0176] Processing circuitry 50 or 78 may, in response to determining that the blood pressure of the patient 4 is abnormal, outputting an alert indicative of the blood pressure of the patient 4 being abnormal (808).

[0177] In some examples, the implantable medical device 10 is an insertable cardiac monitor. In some examples, the insertable cardiac monitor includes a housing configured for subcutaneous implantation in the patient 4, the housing having a length between 40 millimeters (mm) and 60 mm between a first end and a second end, a width less than the length, and a depth less than the width.

[0178] 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.

[0179] 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, DRAM, SRAM, magnetic discs, optical discs, flash memories, or forms of EPROM or EEPROM. The instructions may beexecuted to support one or more aspects of the functionality described in this disclosure.

[0180] 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.

[0181] Example 1. A system comprising: an implantable medical device for implantation within a patient, the implantable medical device comprising one or more sensors configured to sense an optical signal; and processing circuitry configured to: determine a blood pressure of the patient based on the optical signal sensed after the patient undergoes an invasive surgery; determine, based on a normal blood pressure range or a normal rate of blood pressure change over a particular period of time, that the blood pressure of the patient is abnormal; and in response to determining that the blood pressure of the patient is abnormal, output an alert indicative of the blood pressure of the patient being abnormal.

[0182] Example 2. The system of Example 1, wherein the optical signal comprises a photoplethysmographic (PPG) signal.

[0183] Example 3. The system of any of Examples 1 and 2, wherein to determine the blood pressure of the patient based on the optical signal sensed after the patient undergoes an invasive surgery, the processing circuitry is further configured to: determine that the patient has undergone the invasive surgery; and in response to determining that the patient has undergone the invasive surgery, determine the blood pressure of the patient based on the optical signal sensed after the patient undergoes the invasive surgery.

[0184] Example 4. The system of any of Examples 1-3, wherein the processingcircuitry is further configured to: receive independent blood pressure readings from an independent calibration source; and calibrate a blood pressure measurement algorithm used to determine the blood pressure of the patient based on the independent blood pressure readings.

[0185] Example 5. The system of Example 4, wherein the independent blood pressure readings specify first relative changes to blood pressure levels of the patient, and wherein to calibrate the blood pressure measurement algorithm used to determine the blood pressure of the patient based on the independent blood pressure readings, the processing circuitry is further configured to: calibrate the blood pressure measurement algorithm to determine, based on optical signals sensed by the one or more sensors, second relative changes to blood pressure levels of the patient that matches the first relative changes to the blood pressure levels of the patient specified by the independent blood pressure readings.

[0186] Example 6. The system of any of Examples 1-5, wherein to determine that the blood pressure of the patient is abnormal, the processing circuitry is further configured to: determine, based on the blood pressure of the patient, that a rate of blood pressure change over the particular period of time is greater than normal rate of blood pressure change over the particular period of time; and in response to determining that the rate of blood pressure change over the particular period of time is greater than normal rate of blood pressure change over the particular period of time, determine that the blood pressure of the patient is abnormal.

[0187] Example 7. The system of any of Examples 1-5, wherein to determine that the blood pressure of the patient is abnormal, the processing circuitry is further configured to: determine that the blood pressure of the patient is outside the normal blood pressure range; and in response to determining that the blood pressure of the patient is outside the normal blood pressure range, determine that the blood pressure of the patient is abnormal.

[0188] Example 8. The system of any of Examples 1-7, wherein the processing circuitry is further configured to: decrease the normal blood pressure range over time after the patient undergoes the invasive surgery.

[0189] Example 9. The system of any of Examples 1-8, wherein the processing circuitry is further configured to: determine an activity level of the patient; and adjust thenormal blood pressure range based on the activity level of the patient.

[0190] Example 10. The system of Example 9, wherein to determine the activity level of the patient, the processing circuitry is further configured to: obtain, from a computing device that senses motion of the patient, a signal indicative of the activity level of the patient; and determine, based on the signal indicative of the activity level of the patient, the activity level of the patient.

[0191] Example 11. The system of Example 9, wherein to determine the activity level of the patient, the processing circuitry is further configured to: obtain, from the one or more sensors, a signal indicative of a motion of the implantable medical device; and determine, based on the signal indicative of the motion of the implantable medical device, the activity level of the patient.

[0192] Example 12. The system of any of Examples 9-11, wherein to adjust the normal blood pressure range based on the activity level of the patient, the processing circuitry is further configured to: based on determining that the activity level of the patient is low, decrease a high threshold of the normal blood pressure range.

[0193] Example 13. The system of any of Examples 9-11, wherein to adjust the normal blood pressure range based on the activity level of the patient, the processing circuitry is further configured to: based on determining that the activity level of the patient is high, increase a high threshold of the normal blood pressure range.

[0194] Example 14. The system of any of Examples 1-13, wherein the processing circuitry is further configured to: determine a posture of the patient; and adjust the normal blood pressure range based on the posture of the patient.

[0195] Example 15. The system of Example 14, wherein to adjust the normal blood pressure range based on the posture of the patient, the processing circuitry is further configured to: determine that the patient is lying down; and based on determining that the patient is lying down, decrease a high threshold of the normal blood pressure range.

[0196] Example 16. The system of any of claims 1-15, wherein the implantable medical device is implanted in the patient prior to the patient undergoing the invasive surgery; wherein the one or more sensors are further configured to, prior to the patient undergoing the invasive surgery, sense one or more baseline optical signals; wherein the processing circuitry is further configured to determine, based on the one or more baseline optical signals, a baseline blood pressure range for the patient.

[0197] Example 17. The system of Example 16, wherein the processing circuitry is further configured to: determine the normal blood pressure range based on the baseline blood pressure range for the patient.

[0198] Example 18. The system of any of Examples 1-17, wherein the processing circuitry is further configured to: determine a medication schedule of the patient; and adjust the normal blood pressure range based on the medication schedule of the patient.

[0199] Example 19. The system of any of Examples 1-18, wherein to determine the blood pressure of the patient, the processing circuitry is further configured to: determine, based on optical signals sensed by the one or more sensors, blood pressure levels of the patient according a schedule, wherein the schedule specifies a frequency of determining the blood pressure levels of the patient during an initial time period after the patient undergoes the invasive surgery, and wherein the schedule tapers the frequency of determining the blood pressure levels of the patient over time after the initial time period.

[0200] Example 20. The system of any of Examples 1-19, wherein the implantable medical device includes the processing circuitry.

[0201] Example 21. The system of any of Examples 1-19, wherein the system further comprises an external device that includes the processing circuitry.

[0202] Example 22. The system of any of Examples 1-21, wherein the implantable medical device comprises an insertable cardiac monitor.

[0203] Example 23. The system of Example 22, wherein the insertable cardiac monitor comprises: a housing configured for subcutaneous implantation in the patient, the housing having a length between 40 millimeters (mm) and 60 mm between a first end and a second end, a width less than the length, and a depth less than the width.

[0204] Example 24. A method comprising: sensing, by one or more sensors of an implantable medical device for implantation within a patient, an optical signal; determining, by processing circuitry, a blood pressure of the patient based on the optical signal sensed after the patient undergoes an invasive surgery; determining, by the processing circuitry and based on a normal blood pressure range or a normal rate of blood pressure change over a particular period of time, that the blood pressure of the patient is abnormal; and in response to determining that the blood pressure of the patient is abnormal, outputting, by the processing circuitry, an alert indicative of the blood pressureof the patient being abnormal.

[0205] Example 25. The method of Example 24, wherein the optical signal is a photoplethysmographic (PPG) signal.

[0206] Example 26. The method of any of Examples 24 and 25, wherein determining the blood pressure of the patient based on the optical signal sensed after the patient undergoes an invasive surgery further comprises: determining, by the processing circuitry, that the patient has undergone the invasive surgery; and in response to determining that the patient has undergone the invasive surgery, determining, by the processing circuitry, the blood pressure of the patient based on the optical signal sensed after the patient undergoes the invasive surgery.

[0207] Example 27. The method of any of Examples 24-26, further comprising: receiving, by the processing circuitry, independent blood pressure readings from an independent calibration source; and calibrating, by the processing circuitry, a blood pressure measurement algorithm used to determine the blood pressure of the patient based on the independent blood pressure readings.

[0208] Example 28. The method of Example 27, wherein the independent blood pressure readings specify first relative changes to blood pressure levels of the patient, and wherein calibrating the blood pressure measurement algorithm used to determine the blood pressure of the patient based on the independent blood pressure readings further comprises: calibrating, by the processing circuitry, the blood pressure measurement algorithm to determine, based on optical signals sensed by the one or more sensors, second relative changes to blood pressure levels of the patient that matches the first relative changes to the blood pressure levels of the patient specified by the independent blood pressure readings.

[0209] Example 29. The method of any of Examples 24-28, wherein determining that the blood pressure of the patient is abnormal further comprises: determining, by the processing circuitry and based on the blood pressure of the patient, that a rate of blood pressure change over the particular period of time is greater than normal rate of blood pressure change over the particular period of time; and in response to determining that the rate of blood pressure change over the particular period of time is greater than normal rate of blood pressure change over the particular period of time, determining, by the processing circuitry, that the blood pressure of the patient is abnormal.

[0210] Example 30. The method of any of Examples 24-28, wherein determining that the blood pressure of the patient is abnormal further comprises: determining, by the processing circuitry, that the blood pressure of the patient is outside the normal blood pressure range; and in response to determining that the blood pressure of the patient is outside the normal blood pressure range, determining, by the processing circuitry, that the blood pressure of the patient is abnormal.

[0211] Example 31. The method of any of Examples 24-30, further comprising: decreasing, by the processing circuitry, the normal blood pressure range over time after the patient undergoes the invasive surgery.

[0212] Example 32. The method of any of Examples 24-31, further comprising: determining, by the processing circuitry, an activity level of the patient; and adjusting, by the processing circuitry, the normal blood pressure range based on the activity level of the patient.

[0213] Example 33. The method of Example 32, wherein determining the activity level of the patient further comprises: obtaining, by the processing circuitry and from a computing device that senses motion of the patient, a signal indicative of the activity level of the patient; and determining, by the processing circuitry and based on the signal indicative of the activity level of the patient, the activity level of the patient.

[0214] Example 34. The method of Example 32, wherein determining the activity level of the patient further comprises: obtaining, by the processing circuitry and from the one or more sensors, a signal indicative of a motion of the implantable medical device; and determining, based on the signal indicative of the motion of the implantable medical device, the activity level of the patient.

[0215] Example 35. The method of any of Examples 32-34, wherein adjusting the normal blood pressure range based on the activity level of the patient further comprises: based on determining that the activity level of the patient is low, decreasing, by the processing circuitry, a high threshold of the normal blood pressure range.

[0216] Example 36. The method of any of Examples 32-34, wherein adjusting the normal blood pressure range based on the activity level of the patient further comprises: based on determining that the activity level of the patient is high, increasing, by the processing circuitry a high threshold of the normal blood pressure range.

[0217] Example 37. The method of any of Examples 24-36, further comprising:determining, by the processing circuitry, a posture of the patient; and adjusting, by the processing circuitry, the normal blood pressure range based on the posture of the patient.

[0218] Example 38. The method of Example 37, wherein adjusting the normal blood pressure range based on the posture of the patient further comprises: determining, by the processing circuitry, that the patient is lying down; and based on determining that the patient is lying down, decreasing, by the processing circuitry, a high threshold of the normal blood pressure range.

[0219] Example 39. The method of any of Examples 24-38, wherein the implantable medical device is implanted in the patient prior to the patient undergoing the invasive surgery, further comprising: sensing, by the one or more sensors and prior to the patient undergoing the invasive surgery, one or more baseline optical signals; and determining, by the processing circuitry and based on the one or more baseline optical signals, a baseline blood pressure range for the patient.

[0220] Example 40. The method of Example 39, further comprising: determining, by the processing circuitry, the normal blood pressure range based on the baseline blood pressure range for the patient.

[0221] Example 41. The method of any of Examples 24-40, further comprising: determining, by the processing circuitry, a medication schedule of the patient; and adjusting, by the processing circuitry, the normal blood pressure range based on the medication schedule of the patient.

[0222] Example 42. The method of any of Examples 24-41, wherein determining the blood pressure of the patient further comprises: determining, by the processing circuitry and based on optical signals sensed by the one or more sensors, blood pressure levels of the patient according a schedule, wherein the schedule specifies a frequency of determining the blood pressure levels of the patient during an initial time period after the patient undergoes the invasive surgery, and wherein the schedule tapers the frequency of determining the blood pressure levels of the patient over time after the initial time period.

[0223] Example 43. The method of any of Examples 24-42, wherein the implantable medical device includes the processing circuitry.

[0224] Example 44. The method of any of Examples 24-42, wherein an external device that includes the processing circuitry

[0225] Example 45. The method of any of Examples 24-44, wherein theimplantable medical device comprises an insertable cardiac monitor.

[0226] Example 46. The method of Example 45, wherein the insertable cardiac monitor comprises: a housing configured for subcutaneous implantation in the patient, the housing having a length between 40 millimeters (mm) and 60 mm between a first end and a second end, a width less than the length, and a depth less than the width.

[0227] Example 47. An apparatus comprising means for performing the method of any of Examples 24-46.

Claims

WHAT IS CLAIMED:

1. A system comprising: an implantable medical device for implantation within a patient, the implantable medical device comprising one or more sensors configured to sense an optical signal; and processing circuitry configured to: determine a blood pressure of the patient based on the optical signal sensed after the patient undergoes an invasive surgery; determine, based on a normal blood pressure range or a normal rate of blood pressure change over a particular period of time, that the blood pressure of the patient is abnormal; and in response to determining that the blood pressure of the patient is abnormal, output an alert indicative of the blood pressure of the patient being abnormal.

2. The system of claim 1, wherein the optical signal comprises a photoplethysmographic (PPG) signal.

3. The system of any of claims 1 and 2, wherein to determine the blood pressure of the patient based on the optical signal sensed after the patient undergoes an invasive surgery, the processing circuitry is further configured to: determine that the patient has undergone the invasive surgery; and in response to determining that the patient has undergone the invasive surgery, determine the blood pressure of the patient based on the optical signal sensed after the patient undergoes the invasive surgery.

4. The system of any of claims 1-3, wherein the processing circuitry is further configured to: receive independent blood pressure readings from an independent calibration source; and calibrate a blood pressure measurement algorithm used to determine the blood pressure of the patient based on the independent blood pressure readings.

5. The system of claim 4, wherein the independent blood pressure readings specify first relative changes to blood pressure levels of the patient, and wherein to calibrate the blood pressure measurement algorithm used to determine the blood pressure of the patient based on the independent blood pressure readings, the processing circuitry is further configured to: calibrate the blood pressure measurement algorithm to determine, based on optical signals sensed by the one or more sensors, second relative changes to blood pressure levels of the patient that matches the first relative changes to the blood pressure levels of the patient specified by the independent blood pressure readings.

6. The system of any of claims 1-5, wherein to determine that the blood pressure of the patient is abnormal, the processing circuitry is further configured to: determine, based on the blood pressure of the patient, that a rate of blood pressure change over the particular period of time is greater than normal rate of blood pressure change over the particular period of time; and in response to determining that the rate of blood pressure change over the particular period of time is greater than normal rate of blood pressure change over the particular period of time, determine that the blood pressure of the patient is abnormal.

7. The system of any of claims 1-5, wherein to determine that the blood pressure of the patient is abnormal, the processing circuitry is further configured to: determine that the blood pressure of the patient is outside the normal blood pressure range; and in response to determining that the blood pressure of the patient is outside the normal blood pressure range, determine that the blood pressure of the patient is abnormal.

8. The system of any of claims 1-7, wherein the processing circuitry is further configured to: decrease the normal blood pressure range over time after the patient undergoes the invasive surgery.

9. The system of any of claims 1-8, wherein the processing circuitry is further configured to: determine an activity level of the patient; and adjust the normal blood pressure range based on the activity level of the patient.

10. The system of claim 9, wherein to determine the activity level of the patient, the processing circuitry is further configured to: obtain, from a computing device that senses motion of the patient, a signal indicative of the activity level of the patient; and determine, based on the signal indicative of the activity level of the patient, the activity level of the patient.

11. The system of claim 9, wherein to determine the activity level of the patient, the processing circuitry is further configured to: obtain, from the one or more sensors, a signal indicative of a motion of the implantable medical device; and determine, based on the signal indicative of the motion of the implantable medical device, the activity level of the patient.

12. The system of any of claims 1-11, wherein the processing circuitry is further configured to: determine a posture of the patient; and adjust the normal blood pressure range based on the posture of the patient.

13. The system of any of claims 1-12, wherein the implantable medical device is implanted in the patient prior to the patient undergoing the invasive surgery, wherein the one or more sensors are further configured to, prior to the patient undergoing the invasive surgery, sense one or more baseline optical signals, wherein the processing circuitry is further configured to determine, based on the one or more baseline optical signals, a baseline blood pressure range for the patient, and wherein the processing circuitry is further configured to:determine the normal blood pressure range based on the baseline blood pressure range for the patient.

14. The system of any of claims 1-13, wherein the processing circuitry is further configured to: determine a medication schedule of the patient; and adjust the normal blood pressure range based on the medication schedule of the patient.

15. The system of any of claims 1-14, wherein to determine the blood pressure of the patient, the processing circuitry is further configured to: determine, based on optical signals sensed by the one or more sensors, blood pressure levels of the patient according a schedule, wherein the schedule specifies a frequency of determining the blood pressure levels of the patient during an initial time period after the patient undergoes the invasive surgery, and wherein the schedule tapers the frequency of determining the blood pressure levels of the patient over time after the initial time period.

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