APPARATUS AND METHOD FOR IDENTIFYING A COUGHING EVENT
20190336039 ยท 2019-11-07
Assignee
- University Of Maryland, Baltimore (Baltimore, MD)
- University Of Maryland, College Park (College Park, MD)
Inventors
- Stella HINES (Baltimore, MD, US)
- Lucia FERNANDEZ (Monroe, NJ, US)
- Jessica BAER (Holladay, UT, US)
- Andrew KADISH (Pikesville, MD, US)
- Yousuf NAVED (North Potomac, MD, US)
- Farah VEJZAGIC (Baltimore, MD, US)
- Ian WHITE (Ellicott City, MD, US)
Cpc classification
A61B5/6801
HUMAN NECESSITIES
A61B5/1107
HUMAN NECESSITIES
G16H50/20
PHYSICS
A61B5/7264
HUMAN NECESSITIES
A61B5/0816
HUMAN NECESSITIES
International classification
A61B5/08
HUMAN NECESSITIES
A61B5/00
HUMAN NECESSITIES
A61B5/11
HUMAN NECESSITIES
Abstract
Provided is a method for identifying a coughing event, the method including obtaining, from a sensor included in a monitoring device worn by a patient, a plurality of digital voltage values, analyzing the plurality of digital voltage values to identify a physiological event based on (i) a change in magnitude of the digital voltage values and (ii) a duration of the change in the magnitude of the digital voltage values, the change in the magnitude of the digital voltage values and the duration of the change in the magnitude of the digital voltage values representing a first point in a two-dimensional feature space, and categorizing the identified physiological event as the coughing event based on a threshold hyperplane existing in the two-dimensional feature space.
Claims
1. A method for identifying a coughing event, the method comprising: obtaining, from a sensor included in a monitoring device worn by a patient, a plurality of digital voltage values; and analyzing the plurality of digital voltage values to identify a physiological event based on (i) a change in magnitude of the digital voltage values and (ii) a duration of the change in the magnitude of the digital voltage values, the change in the magnitude of the digital voltage values and the duration of the change in the magnitude of the digital voltage values representing a first point in a two-dimensional feature space; and categorizing the identified physiological event as the coughing event based on a threshold hyperplane existing in the two-dimensional feature space.
2. The method for identifying the coughing event according to claim 1, wherein the threshold hyperplane is obtained by linear regression to optimize a margin between (i) a first class of one or more points in the two-dimensional feature space corresponding to a physiological event that is a coughing event and (ii) a second class of one or more points in the two-dimensional feature space corresponding to a physiological event that is not a coughing event.
3. The method for identifying the coughing event according to claim 2, wherein the threshold hyperplane is updated based on a result of categorizing the identified physiological event as the coughing event such that (i) when the identified physiological event is categorized as the coughing event, the first point in the two-dimensional feature space is added to the first class of the one or more points in the two-dimensional feature space and (ii) when the identified physiological event is not categorized as the coughing event, the first point in the two-dimensional feature space is added to the second class of one or more points in the two-dimensional feature space.
4. The method for identifying the coughing event according to claim 2, further comprising: receiving input from the patient identifying a coughing event at an inputted time; creating, using digital voltage values from among the plurality of digital voltage values corresponding to the inputted time, a point in the two-dimensional feature space; and updating threshold hyperplane to add the created point to the first class of the one or more points in the two-dimensional feature space.
5. The method for identifying the coughing event according to claim 1, further comprising when the identified physiological event is categorized as the coughing event, outputting an indication of the coughing event to a display.
6. The method for identifying the coughing event according to claim 1, further comprising: when the identified physiological event is categorized as the coughing event, storing data representing a time at which the coughing event occurred; and outputting, to a display, a graph representing a frequency of coughing events based on the stored data.
7. The method for identifying the coughing event according to claim 1, wherein the sensor is a piezoelectric sensor configured to output a voltage value in response to strain placed upon the piezoelectric sensor by a patient as a result of a physiological event.
8. An apparatus for identifying a coughing event, the apparatus comprising: a processor; and a non-transitory memory having stored thereon executable instructions, which when executed cause the processor to perform operations including: obtaining, from a sensor included in a monitoring device worn by a patient, a plurality of digital voltage values; analyzing the plurality of digital voltage values to identify a physiological event based on (i) a change in magnitude of the digital voltage values and (ii) a duration of the change in the magnitude of the digital voltage values, the change in the magnitude of the digital voltage values and the duration of the change in the magnitude of the digital voltage values representing a first point in a two-dimensional feature space; and categorizing the identified physiological event as the coughing event based on a threshold hyperplane existing in the two-dimensional feature space.
9. The apparatus for identifying the coughing event according to claim 8, wherein the threshold hyperplane is obtained by linear regression to optimize a margin between (i) a first class of one or more points in the two-dimensional feature space corresponding to a physiological event that is a coughing event and (ii) a second class of one or more points in the two-dimensional feature space corresponding to a physiological event that is not a coughing event.
10. The apparatus for identifying the coughing event according to claim 9, wherein the threshold hyperplane is updated based on a result of categorizing the identified physiological event as the coughing event such that (i) when the identified physiological event is categorized as the coughing event, the first point in the two-dimensional feature space is added to the first class of the one or more points in the two-dimensional feature space and (ii) when the identified physiological event is not categorized as the coughing event, the first point in the two-dimensional feature space is added to the second class of one or more points in the two-dimensional feature space.
11. The apparatus for identifying the coughing event according to claim 9, wherein the executable instructions further cause the processor to perform operations including: receiving input from the patient identifying a coughing event at an inputted time; creating, using digital voltage values from among the plurality of digital voltage values corresponding to the inputted time, a point in the two-dimensional feature space; and updating threshold hyperplane to add the created point to the first class of the one or more points in the two-dimensional feature space.
12. The apparatus for identifying the coughing event according to claim 8, wherein the executable instructions further cause the processor to perform an operation of when the identified physiological event is categorized as the coughing event, outputting an indication of the coughing event to a display.
13. The apparatus for identifying the coughing event according to claim 8, wherein the executable instructions further cause the processor to perform operations including: when the identified physiological event is categorized as the coughing event, storing data representing a time at which the coughing event occurred; and outputting, to a display, a graph representing a frequency of coughing events based on the stored data.
14. The apparatus for identifying the coughing event according to claim 8, wherein the sensor is a piezoelectric sensor configured to output a voltage value in response to strain placed upon the piezoelectric sensor by a patient as a result of a physiological event.
15. A system for identifying a coughing event, the system comprising: a monitoring device including a microcontroller and a piezoelectric sensor configured to output voltage values to the microcontroller in response to strain placed upon the piezoelectric sensor by a patient as a result of a physiological event, the microcontroller being capable of performing short-range wireless communication; and a computer device capable of performing the short-range wireless communication, wherein microcontroller converts the voltage values obtained from the piezoelectric sensor to digital voltage values, and outputs the digital voltage values to the computer device using the short-range wireless communication, wherein the computer device analyzes the plurality of digital voltage values to identify a physiological event based on (i) a change in magnitude of the digital voltage values and (ii) a duration of the change in the magnitude of the digital voltage values, the change in the magnitude of the digital voltage values and the duration of the change in the magnitude of the digital voltage values representing a first point in a two-dimensional feature space, wherein the threshold hyperplane is obtained by linear regression to optimize a margin between (i) a first class of one or more points in the two-dimensional feature space corresponding to a physiological event that is a coughing event and (ii) a second class of one or more points in the two-dimensional feature space corresponding to a physiological event that is not a coughing event, wherein the computer device categorizes the identified physiological event as the coughing event based on a threshold hyperplane existing in the two-dimensional feature space, and wherein when the identified physiological event is categorized as the coughing event, the computer device outputs an indication of the coughing event to a display.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements.
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DETAILED DESCRIPTION OF THE INVENTION
[0033] Provided is a device configured to identify and monitor a coughing event/chronic cough over long periods of time, therefore aiding pulmonologists in formulating an accurate diagnosis and tracking the efficacy of potential treatments. The device can be further configured to determine cough events, such as by having machining learning processes to analyze data using a support vector machine (SVM) machine learning algorithm, for example, to cluster coughing events together based on change in a digital voltage reading. Information obtained from the device can be transferred to an external device, such as a personal computer, mobile device, or dedicated display device. In one embodiment, the device can communicate with a mobile device using an application wirelessly via Bluetooth. Thus, doctors can securely access patient data in real time. In another embodiment, the device and/or the app can receive input of patient notes to increase the accuracy of subjective cough data for review by pulmonologists. Thus, the device provides pulmonologists with the objective and subjective data needed to best treat their patients' chronic cough.
[0034]
[0035] The attachment portion 104 is a nylon webbing belt. However, the attachment portion 104 is not limited to this configuration, and the attachment portion 104 may be configured in another manner that would allow the monitor device 100 to be comfortably worn by the patient for an extended period of time.
[0036] Additionally, the monitor device 100 is not limited to a configuration including the attachment portion 104, that is, the monitor device 100 could alternatively be configured to be positioned on the patient via an adhesive patch.
[0037]
[0038] The monitor device 100 is configured to be comfortable to a patient such that the patient can wear the device for an extended period time. According to one embodiment, the monitor device 100 is intended to be tightly strapped to the upper abdominal region of the patient in order to obtain accurate readings from the sensor 204. In order to ensure maximum comfort, the monitor device 100 ideally weights less than 2 lbs, the sensor 204 is a flexible sensor capable of lying on an outside of the housing 102, and the size of the housing 102 is smaller than 531. However, one of ordinary skill in the art would understand that monitor device 100 is not limited to such a configuration, and may be configured as necessary to ensure comfort an individual patient
[0039] The power supply 204 is chosen to allow the microcontroller to be remain fully active through a 24 hour period between charging of the monitor device 100. For example, in order to calculate battery requirements for the power supply 204, the typical current draw of the microcontroller 202 of less than 35 mA is rounded up to 40 mA to account for the current draw of sensor 203 and any fluctuations. Since the monitor device 100 is configured to operate for at least 24 hours between charging, the required battery capacity of the power supply 204 is calculated to be approximately 960 mAh. To meet this battery capacity, according to one embodiment of the present invention, the power supply 204 is implemented as a rechargeable lithium ion 3.7 V 2 Ah battery. However, the power supply 204 could be implemented as another battery type or other power supplies could be used in the monitor device 100.
[0040] For example, if the microcontroller 202 has a low power mode, the microcontroller 202 could be programmed to only be fully active when an input from the sensor 206 reaches a predetermined threshold, thereby allowing the microcontroller 202 to draw much less current, that is, only draw the predicted current of 35-45 mA when some physiological phenomenon such as a cough or yawn caused the input to cross that specified value. Configuration of the microcontroller 202 in this manner would allow the power supply 204 to be implemented using a battery with less storage capacity.
[0041] The sensor 206 is a piezoelectric strain sensor configured such that when the patient coughs, the patient's rib cage will push against the sensor 206 thereby changing the resistance of the piezoelectric circuit and creating an overall change in voltage.
[0042] A piezoelectric strain sensor was selected as the sensor 206 over other alternatives such as a microphone, an electromyography sensor, and an accelerometer due to a combination of ease of patient compliance, least amount of interference with daily life of a patient, and ability to differentiate between a couch and other events such as a laugh or deep breathing. However, the sensor 203 is not limited to only a piezoelectric strain sensor, and other types of sensors could be used which could satisfactory achieve the combination of ease of patient compliance, least amount of interference with daily life of a patient, and ability to differentiate between a couch and other events such as a laugh or deep breathing.
[0043] An example of the one embodiment of integration of the microcontroller 202 and the sensor 206 is illustrated in
[0044] As illustrated in
[0045]
[0046] According to one embodiment, the computer device 402 executes a computer program to communicate with the monitor device 100 to obtain data and perform analysis on the received data to determine whether or not a coughing event has occurred.
[0047]
[0048] At Step 502, data indicating digital voltage values is transferred from the microcontroller 202 included in the monitor device 100 to the computer device 402 wirelessly via short-range wireless communication such as Bluetooth. In one embodiment, the data can be continuously transferred from the monitor device 100 to computer device 402 such that the computer device 402 receives the data as a continuous stream of digital voltage values and/or the data at the time of detection of a change in the digital voltage values exceeds a threshold value. Alternatively, the monitor device 100 can include memory or storage, such as a flash memory, to store the digital voltage values with specific timestamps for later syncing with the computer device 402 allowing for batch transfer of the data.
[0049] After the data is received from the monitor device 100, the computer device 402 may perform an optional step 504 of signal normalization to compensate or correct the received data. For example, signal normalization may be performed in order to correct or compensate for a patient's body mass index (BMI), waist size, movement during measurement, and/or incorrect positioning of the monitor device 100.
[0050] Additionally, when the attachment portion 104 is configured as the nylon webbing belt, tension of the belt is important for accurate readings using the sensor 206. At step 504, the computer device 402 may characterize the tautness of the belt based on the received data and perform further normalization of the data as necessary.
[0051] At Step 506, the computer device 402 analyzes the data received from the monitor device 100 to determine whether or not a coughing event has occurred.
[0052] In one embodiment, a machine learning such as support vector machine (SVM) algorithm is utilized to cluster the data received from the monitor device 100 according to the characteristics of a change in the digital voltage values and/or a duration of the change in the digital voltage values in order to identify coughing events from the data received from the monitor device 100 based on corresponding characteristics associated with each of different kinds of physiological phenomena, such as coughing, yawning, laughing, etc., thereby allowing the computer device 402 to distinguish coughing events from other phenomena.
[0053] In particular, the SVM algorithm utilizes a threshold hyperplane in a two-dimensional feature space obtained by linear regression to optimize a margin between a first class of data points in the two-dimensional feature space corresponding to physiological phenomena categorized as coughing events and a second class of data points in the two-dimensional feature space corresponding to physiological phenomena not categorized as coughing events. However, the SVM algorithm is not limited to classifying data into one of two classes, and further classes can be utilized to differentiate between each of the different kinds of the physiological phenomena above, which would result in multiple threshold hyperplanes differentiating between the physiological phenomena.
[0054] The present invention was implemented using a semi-supervised SVM algorithm based on test datasets and training datasets obtained as a result of initial testing the monitor device 100. However, it should be understood that the present invention is not limited in such a manner and that the SVM algorithm may be implemented unsupervised or fully supervised with a larger training dataset.
[0055]
[0056] As can be seen from
[0057] On the other hand,
[0058] As can be seen from
[0059] Similarly, as can be seen from
[0060] Directly comparing the graphs illustrated in
[0061] Based on the results of the testing, the initial testing data was partitioned into feature points in the two-dimensional feature space and categorized according to the physiological phenomena present in order to create test datasets and training datasets representing the first class of data points corresponding to physiological phenomena categorized as coughing events and the second class of data points corresponding to physiological phenomena not categorized as coughing events in order to optimize the SVM algorithm utilized at Step 506.
[0062] The initial testing data may be partitioned into the features points in many different ways, for example, a given dataset could be partitioned into a two-dimensional feature point representing a first numerical feature corresponding to a magnitude of a change in voltage of the digital voltage values and a second numerical feature representing a duration from when the voltage increases and subsequently returns back to an initial value. It should be understood that the SVM algorithm is not limited to a two-dimensional feature space, and n-dimensional feature vectors representing datasets in a n-dimensional feature space may be used.
[0063] The labeling of these datasets enabled the training of the SVM algorithm and allowed for initial measurements of accuracy to estimate the sensitivity and specificity that can be expected for the cough detection system 400. Initial testing after the training of the SVM algorithm resulted in just a 1% error in identification and categorization of coughing events, thereby demonstrating improvement in cough detection by the present invention over the previously described conventional techniques.
[0064] Based on the trained SVM algorithm described above, the computer device 402 is able to, at Step 506, differentiate and identify a coughing event from other physiological phenomena by partitioning the data received from the monitor device 100 into feature points in the two-dimensional feature space based on the characteristics of a change in magnitude of the digital voltage values and/or a duration of the change in magnitude of the digital voltage values indicated by the data and categorizing the feature points according to the threshold hyperplane obtained by training the SVM algorithm.
[0065] Training of the SVM algorithm may be updated based on identified coughing events such that feature points determined to identify a coughing event may added to the first class of data points in the two-dimensional feature space corresponding to physiological phenomena categorized as coughing events, whereas feature points determined not to identify a coughing event may be added to the second class of data points in the two-dimensional feature space corresponding to physiological phenomena not categorized as coughing events, thereby allowing the SVM algorithm to update the threshold hyperplane based on new data obtained from the monitoring device 100.
[0066] Additionally, the initial testing data provided crucial information on the placement of the monitor device 100, and in particular, after testing the monitoring device 100 on the lower and mid-abdominals, it was found that placing the monitoring device 100 so that the sensor 206 is located on the ribs of the patient, specifically the eighth or ninth intercostal space near the costal cartilage, provided the clearest data. Further, it was also discovered, that clearest data is obtained by the monitoring device 100 when the attachment portion 104 has very low elasticity, thereby resulting in the attachment portion 104 being implemented as a nylon webbing belt in the present invention. The computer device 402 may utilize this initial testing data during the optional Step 504 of signal normalization to compensate or correct the received data.
[0067] In order to reduce the need for signal normalization at Step 504, clinicians may first place the monitoring device 100 on the patient under the guidance of carefully crafted instructions, thereby increasing the likelihood that the monitoring device 100 is in the optimal location for sensing the expansion of the lungs and the subsequent contraction associated with coughing and that the monitoring device 100 is also comfortable for the patient.
[0068] At Step 508, the computer device 402 will present the analyzed data received from the monitoring device 100 through the graphical representation of a frequency of coughing events via a display so that it may be viewed by the patient or the patient's doctor.
[0069] As described above, data indicating digital voltage values is transferred from the monitoring device 100 to the computer device 402 for analysis. However, in another embodiment, the analysis functions performed by the computer device 402 may be implemented by the microcontroller 202 included in the monitoring device 100 such that only the results of the analysis are communicated from the monitoring device 100 to the computer device 402 for display via the computer program executed by the computer device 402.
[0070] As noted above, the computer device 402 may be configured as a smartphone. In such a configuration, the computer program executed by the computer device 402 may take the form of a smartphone application (app) and the computer device 402 may be configured to be able to correlate other health data with the frequency of coughing events to provide a better overall idea of the patient's daily health patterns. In other words, a context for the frequency of coughing events can be provided by integrating the functions of the present invention with data from other wearable sensors, such as number of steps/distance traveled obtained from a wearable device that functions as a pedometer, real-time heart rate from a wearable device that functions as a heart-rate monitor, etc.
[0071] Another embodiment of the invention allows the objective measurements of coughing events by the cough detection system 400 with subjective feedback from the patient. Specifically, the computer device 402 is configured to allow patient input using the executed computer program at the time of a coughing event, as illustrated in
[0072] For example, if the patient begins to cough while exercising, the patient could open the computer program on the computer device 402, input the coughing event, and label the coughing event with appropriate keywords so as to indicate that the coughing event is correlated with exercising.
[0073] Additionally, by identifying a coughing event, the cough detection system 400 may be able to combine the subjective feedback from the patient with characteristics of the digital voltage values at the time of the patient feedback in order to update the SVM algorithm.
[0074] By receiving input from the patient identifying a coughing even at a given time, the cough detection system 400 is able to retrieve data indicating characteristics of a change in the digital voltage values and/or a duration of the change in the digital voltage values received form the monitoring device 100 at the given time, create a feature point in the two-dimensional feature space using the retrieved data, and add the newly created feature point to the first class of data points in the two-dimensional feature space corresponding to physiological phenomena categorized as coughing events, thereby allowing the SVM algorithm to update the threshold hyperplane based on input from the patient.
[0075] In addition to being able to label coughing events with keywords, a patient can also keep a journal consisting of any and all notes the patient thinks might be helpful to a pulmonologist. Specifically, the patient could discuss use of the cough detection system 400 with a pulmonologist, and the pulmonologist will be able to give patients examples of pertinent information they would like noted. By using the cough detection system 400 in such a manner, both the objective measurements of coughing events by the cough detection system 400 with subjective feedback from the patient are able to provide the pulmonologist with more reliable when making a diagnosis or monitoring the success of a treatment than current techniques.
[0076] As described above, the cough detection system 400 has demonstrated an improvement over conventional technique related to identification of a coughing event from among other physiological phenomena. Further, as described above, the principles of design for the monitoring device 100 of the cough detection system 400 are based around patient comfort, and as such, allow the monitoring device 100 to be used for long periods of time, e.g., 24 hour periods, and allow the monitoring device 100 to be easily used by the patient, thereby increasing patient compliance with prescribed use by a doctor.
[0077] The present disclosure includes the use of computer programs or algorithms. The programs or algorithms can be stored on a non-transitory computer-readable medium for causing a computer, such as the one or more processors, to execute the steps described in
[0078] The computer programs, which can also be referred to as programs, software, software applications, applications, components, or code, include machine instructions for a programmable processor, and can be implemented in a high-level procedural language, an object-oriented programming language, a functional programming language, a logical programming language, or an assembly language or machine language. The term computer-readable recording medium refers to any computer program product, apparatus or device, such as a magnetic disk, optical disk, solid-state storage device, memory, and programmable logic devices (PLDs), used to provide machine instructions or data to a programmable data processor, including a computer-readable recording medium that receives machine instructions as a computer-readable signal.
[0079] By way of example, a computer-readable medium can comprise DRAM, RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired computer-readable program code in the form of instructions or data structures and that can be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor. Disk or disc, as used herein, include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and Blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above are also included within the scope of computer-readable media.
[0080] Use of the phrases capable of, capable to, operable to, or configured to in one or more embodiments, refers to some apparatus, logic, hardware, and/or element designed in such a way to enable use of the apparatus, logic, hardware, and/or element in a specified manner.
[0081] The subject matter of the present disclosure is provided as examples of apparatus, systems, methods, and programs for performing the features described in the present disclosure. However, further features or variations are contemplated in addition to the features described above. It is contemplated that the implementation of the components and functions of the present disclosure can be done with any newly arising technology that may replace any of the above implemented technologies.
[0082] Additionally, the above description provides examples, and is not limiting of the scope, applicability, or configuration set forth in the claims. Changes may be made in the function and arrangement of elements discussed without departing from the spirit and scope of the disclosure. Various embodiments may omit, substitute, or add various procedures or components as appropriate. For instance, features described with respect to certain embodiments may be combined in other embodiments.
[0083] Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the spirit or scope of the present disclosure. Throughout the present disclosure the terms example, examples, or exemplary indicate examples or instances and do not imply or require any preference for the noted examples. Thus, the present disclosure is not to be limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed.