Device, system and method for detecting a cardiac and/or respiratory disease of a subject

Abstract

The present invention relates to device, system and method for detecting a cardiac and/or respiratory disease of a subject. The proposed device comprises a sound input (20) for obtaining a sound signal representing sounds generated by the subject's body; a motion input (21) for obtaining a motion signal representing motions generated by the subject's body; and a processor (22) for processing the obtained sound signal and motion signal. This processing includes identifying inhalation and/or exhalation periods of the subject based on the motion signal, detecting abnormal lung sounds during inhalation and/or exhalation periods based on the sound signal, determining abnormal lung sound characteristics of the detected abnormal lung sounds, determining breathing characteristics of the subject's breathing based on the sound signal, determining the phase of the abnormal lung sounds in the inhalation-exhalation cycle, and detecting a cardiac and/or respiratory disease of the subject based on the determined abnormal lung sound characteristics, the determined breathing characteristics and the determined phase of the abnormal lung sounds in the inhalation-exhalation cycle.

Claims

1. A device for detecting a cardiac and/or respiratory disease of a subject, comprising: a sound input for obtaining a sound signal representing sounds generated by the subject's body; a motion input for obtaining a motion signal representing breathing motions generated by the subject's body; and a processor for processing the obtained sound signal and motion signal by: identifying inhalation and/or exhalation periods of the subject based on the motion signal, wherein the inhalation and/or exhalation periods determine an inhalation-exhalation cycle, detecting abnormal lung sounds during the inhalation and/or exhalation periods based on the sound signal, determining abnormal lung sound characteristics of the detected abnormal lung sounds, determining breathing characteristics of the subject's breathing based on the sound signal, determining a phase for each of the abnormal lung sounds in the inhalation-exhalation cycle, the phase representing the timing of the abnormal lung sounds in the inhalation-exhalation cycle and the location of the abnormal lung sounds in the inhalation-exhalation cycle, and detecting a cardiac and/or respiratory disease of the subject based on the determined abnormal lung sound characteristics, the determined breathing characteristics and the determined phase of the abnormal lung sounds in the inhalation-exhalation cycle.

2. The device as claimed in claim 1, wherein the processor is configured to normalize the determined abnormal lung sound characteristics based on the motion signal and to use the normalized abnormal lung sound characteristics in the detection of the cardiac and/or respiratory disease of the subject.

3. The device as claimed in claim 2, wherein the processor is configured to determine a count of the detected abnormal lung sounds as abnormal lung sound characteristic, to determine a breathing depth of the subject's breathing as breathing characteristic, to normalize the determined abnormal lung sound count based on the determined breathing depth and to determine a degree of severity of disease proportional to the amount of normalized abnormal lung sound count.

4. The device as claimed in claim 1, wherein the processor is configured to determine a count, amplitude and/or frequency of the detected abnormal lung sounds as abnormal lung sound characteristics.

5. The device as claimed in claim 1, wherein the processor is configured to determine a breathing depth and/or breathing rate of the subject's breathing as breathing characteristics.

6. The device as claimed in claim 1, wherein the processor is configured to determine cardiac characteristics based on the sound signal and/or motion signal and to use the determined cardiac characteristics in the detection of the cardiac and/or respiratory disease of the subject.

7. The device as claimed in claim 6, wherein the processor is configured to determine a heart rate, heart rate variability and/or a third heart sound as cardiac characteristics.

8. The device as claimed in claim 1, wherein the processor is configured to determine artifact sounds, in particular coughing, laughing, talking, snoring and/or crying, based on the sound signal and/or the motion signal and to take one or more of the artifact sounds into account in the detection of a cardiac and/or respiratory disease of the subject.

9. The device as claimed in claim 1, wherein the cardiac and/or respiratory disease is one or more of pneumonia, pulmonary edema and heart failure.

10. The device as claimed in claim 1, wherein the processor is configured to monitor the disease progression over time.

11. A system for detecting a cardiac and/or respiratory disease of a subject, comprising: a sound sensor for sensing sounds generated by the subject's body and generating a sound signal representing the sensed sounds; a motion sensor for sensing motions generated by the subject's body and generating a motion signal representing the sensed motions; coupling means for acoustically coupling the sound sensor to the subject's body and for mechanically coupling the motion sensor to the subject's body; and a device as claimed in claim 1 for detecting the cardiac and/or respiratory disease of the subject based on obtained sound signal and motion signal.

12. The system as claimed in claim 11, wherein said sound sensor comprises a microphone, an air pressure sensor, an accelerometer and/or a gyroscope and said motion sensor comprises an accelerometer, a gyroscope and/or a magnetometer.

13. The system as claimed in claim 11, wherein said sound sensor and said motion sensor are arranged in one or more patches configured for being attached to the subject's skin.

14. A method for determining information for use in detecting a cardiac and/or respiratory disease of a subject, comprising: obtaining a sound signal representing sounds generated by the subject's body; obtaining a motion signal representing breathing motions generated by the subject's body; identifying inhalation and/or exhalation periods of the subject based on the motion signal, wherein the inhalation and/or exhalation periods determine an inhalation-exhalation cycle; detecting abnormal lung sounds during the inhalation and/or exhalation periods based on the sound signal; determining a count of the abnormal lung sounds; determining abnormal lung sound characteristics of the detected abnormal lung sounds; determining breathing characteristics of the subject's breathing based on the sound signal; determining a phase for each of the abnormal lung sounds in the inhalation-exhalation cycle, the phase representing the location and the timing of the abnormal lung sounds in the inhalation-exhalation cycle; and issuing the determined abnormal lung sound characteristics, the determined breathing characteristics and the determined phase of the abnormal lung sounds in the inhalation-exhalation cycle for use in detecting the cardiac and/or respiratory disease of the subject based thereon; wherein the count of abnormal lung sounds is indicative of a degree of severity of the cardiac and/or respiratory disease.

15. A computer program product stored on a computer readable medium which includes a set of non-transitory computer readable instructions configured to carry out the steps of the method as claimed in claim 14 when said computer program is carried out on the computer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) These and other aspects of the invention will be apparent from and elucidated with reference to the embodiment(s) described hereinafter. In the following drawings

(2) FIG. 1 shows a schematic diagram of a first embodiment of a system and a device according to the present invention,

(3) FIG. 2 shows a schematic diagram of a second embodiment of a system according to the present invention,

(4) FIG. 3 shows a flowchart of a method for detecting a cardiac and/or respiratory disease of a subject according to the present invention, and

(5) FIG. 4 shows a flowchart of an embodiment of a method for crackle detection according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

(6) FIG. 1 shows a schematic diagram of a first embodiment of a system 1 and a device 2 according to the present invention for detecting a cardiac and/or respiratory disease of a subject 3. The system 1 comprises a sound sensor 4 for sensing sounds generated by the subject's body and generating a sound signal representing the sensed sounds. The sound sensor 4 may e.g. be a microphone that is acoustically coupled to the subject's body, e.g. the subject's chest. The system 1 further comprises a motion sensor 5 for sensing motions generated by the subject's body and generating a motion signal representing the sensed motions. The motion sensor 5 may e.g. be an accelerometer that is mechanically coupled to the subject's body, e.g. the subject's chest or belly area.

(7) For coupling the sound sensor 4 and the motion sensor 5 to the respective portion of the subject's body the system 1 comprises coupling means 6. Said coupling means 6 may be a belt that holds the sensors 4, 5, or a self-adhesive pad that holds the sensors 4, 5, or an adhesive arranged on the bottom side of the sensors 4, 5 for adhering them to the subject's skin. The sensors 4, 5 may also be combined into a sound package that is attached to the subject's body.

(8) The sound signal and the motion signal acquired by the sound sensor 4 and the motion sensor 5 the system 1 may be transferred in a wired or wireless manner to the device 2, e.g. by use of a common interface or separate interfaces for data transfer. Finally, the system 1 comprises the device 2 for detecting a cardiac and/or respiratory disease of the subject based on obtained sound signal and motion signal.

(9) The device 2 is in this embodiment a separate device which is coupled with the sensors 4, 5 in a wired or wireless manner. For instance, via a network, such as a Wifi network, a LAN network, a communications network, or via any other way such as Bluetooth, the signals are retrieved by the device 2 from the sensors 4, 5 or are actively transmitted by the sensors 4, 5. For obtaining the signals the device 2 comprises a sound input 20 for obtaining a sound signal representing sounds generated by the subject's body and a motion input 21 for obtaining a motion signal representing motions generated by the subject's body.

(10) Further, the device 2 comprises a processor 22 for processing the obtained sound signal and motion signal. In said processing inhalation and/or exhalation periods of the subject are identified based on the motion signal. Further, crackles (and/or other lung sounds; only crackles will be used for explanation in the following) are detected during inhalation and/or exhalation periods based on the sound signal. From the detected crackles crackle characteristics are determined, such as a crackle count indicating the number of crackles. From the sound signal breathing characteristics of the subject's breathing are detected. Still further, the phase of the abnormal lung sounds in the inhalation-exhalation cycle is determined. Finally, a cardiac and/or respiratory disease of the subject is detected based on the determined crackle characteristics, the determined breathing characteristics and the determined phase of the abnormal lung sounds in the inhalation-exhalation cycle.

(11) An information about the result of the detection may be issued, e.g. to an external output device 7, which may be doctor's device (e.g. PC, workstation, smartphone, tablet, etc. of the doctor), the central monitor for monitoring patients in a station of a hospital, or a device of the subject 3 (e.g. PC, workstation, smartphone, tablet, etc. of the subject 3). The output device may also be integrated into the device 2, e.g. in the form of a user interface such as a monitor or display.

(12) FIG. 2 shows a schematic diagram of a second embodiment of a system 1′ according to the present invention. In this embodiment the system 1′ comprises a package 8 that may be attached to the chest or back of the subject. The package 8 may include the sensors 4, 5 and the device 2. Hence, the sensed signals are directly processed in the package 8. Additionally, an interface 9 may be provided for outputting the sensed signals and/or the result of the detection performed by the device 2 via a cable 10 (or, alternatively, via a wireless connection). The package 8 is preferably mounted on a pad 11, which may have an adhesive layer on the bottom side so that it can be adhered to the subject's skin.

(13) The combination of motion and sound signals is preferably acquired simultaneously and may be used to diagnose and/or monitor cardiac or respiratory disease (e.g. heart failure or pneumonia) by integrative interpretation of abnormalities in the heart and breathing rates (i.e. too high or too low) and sounds (e.g. a third heart sound in addition to crackling in the lung sounds).

(14) A preferred application of the present invention is an improvement of the Atlas-based respiratory disease detection. The presence of crackles in the lung sounds during inhalation and/or exhalation has been found to be a very specific marker of two of the most common respiratory conditions: pneumonia and pulmonary edema. Pneumonia is the number one cause of death in children under the age of five in Africa and Asia and pulmonary edema is a highly common complication of heart failure and intravenous fluid therapy-associated fluid overload.

(15) For all these conditions, the amount of crackles is proportional to the degree of the condition and the breath volume. Hence, in order to properly interpret and monitor the progression of the condition over time, normalization on basis of the breathing depth is preferably applied. This may be done using the motion sensor. Movements of particular body locations (e.g. the chest wall or the belly portion) are indicative to the breathing depth and may be used to (1) improve the accuracy of a spot-measurement of breathing rate and allow (2) crackle count normalization to (relative) breathing depth; (3) averaging of breathing cycles; (4) trending of disease progression over time; and (5) protocolled standardization of breathing depth (e.g. a minimum relative breathing depth for adults).

(16) For motion sensors, such as accelerometers, to provide an absolute value of the breathing depth, proper patient- and location-specific calibration may be advantageous. However, even without calibration, the motion signals can be beneficially applied to improve accuracy by averaging the crackle characteristics of distinct respiratory cycles and to compare relative (i.e. un-calibrated) breathing depths (which requires consistent placement amongst different subjects). Further, comparing distinct spot-checks (e.g. to determine a trend) requires always the same measuring conditions in terms of sensor position and subject posture.

(17) A flowchart of a method 100 for detecting a cardiac and/or respiratory disease of a subject according to the present invention is shown in FIG. 3. The method 100 comprises the following steps:

(18) S10: obtaining a sound signal representing sounds generated by the subject's body;

(19) S12: obtaining a motion signal representing motions generated by the subject's body;

(20) S14: identifying inhalation and/or exhalation periods of the subject based on the motion signal;

(21) S16: detecting abnormal lung sounds during inhalation and/or exhalation periods based on the sound signal;

(22) S18: determining abnormal lung sound characteristics of the detected abnormal lung sounds;

(23) S20: determining breathing characteristics of the subject's breathing based on the sound signal and determining the phase of the abnormal lung sounds in the inhalation-exhalation cycle; and

(24) S22: detecting a cardiac and/or respiratory disease of the subject based on the determined abnormal lung sound characteristics, the determined breathing characteristics and the determined phase of the abnormal lung sounds in the inhalation-exhalation cycle.

(25) FIG. 4 shows a flowchart of an embodiment of a method 200 for crackle detection according to the present invention. In a first step S30 one or more dedicated algorithms are applied to the sound signals for crackle identification (e.g. using classification via wavelet analysis (as e.g. described in A. Kandaswamy, C. Sathish Kumar, R. P. Ramanathan, S. Jayaraman and N. Malmurugan, “Neural classification of lung sounds using wavelet coefficients,” Computers in Biology and Medicine, pp. 523-537, 2004) or several machine learning methods (as e.g. described in K. Sundaraj, R. Palaniappan, N. U. Ahamed, A. Sundaraj and S. Sundaraj, “Computer based respiratory sound analysis: a systematic review,” IETE Technical Review, vol. 30, no. 3, pp. 248-256, 2013)). In a second step S32 crackle characteristics (e.g. count, timing and/or amplitudes) are determined in relation to the point in time during a respiratory cycle. In a third step S34 crackle characteristics are normalized by using the obtained accelerometer signals as an approximation for the airflow and volume. In a fourth step S36 the crackle characteristics are characterized, in combination with the breathing rate and/or (relative) depth information obtained from the motion signals, to diagnose pneumonia.

(26) In another embodiment coughing, talking and crying may be detected as well from the sound signal and/or the motion signal and may contribute to the accuracy of the diagnosis.

(27) In practical implementations of the proposed system, a dedicated patch, e.g. as shown in FIG. 2, comprises the combination of motion sensor(s) and sound sensor(s), whether or not located at different positions on the body and connected galvanically via e.g. flexible foil or wirelessly to the processor 22, which may also be a central processing unit. Motion may be measured by accelerometer(s), gyroscope(s) or magnetometer(s). Sound signals may be measured by microphone(s), accelerometer(s) or gyroscope(s). Multiple motion sensor and/or multiple sound sensors may be applied to achieve a directional effect or acoustic echo-canceling etc. Such a dedicated patch has the advantage that it maintains the same sensor location over time. This allows trending, which is a very important aspect of lung monitoring.

(28) In another embodiment of the system all elements may be integrated into a portable electronic user device, such as a smartphone. Some existing smartphones comprise already a motion sensor and a sound sensor. Thus, the processor of the smartphone may just be programmed accordingly, e.g. by use of an application program (“app”) to enable the smartphone to carry out the method of the present invention. The network functionality of the smartphone may be used to communicate with e.g. the hospital network, an external output device or another health-network. Other portable electronic user devices, such as smartphones or cameras, that may be worn by the subject in his pocket, e.g. of a jacket, that do not yet have a motion sensor and/or a sound sensor may be equipped accordingly to be able to carry out the method of the present invention. Such portable electronic user devices then represent embodiments of the proposed system.

(29) Generally, different embodiments of the proposed system and device may be implemented on basis of their clinical application. The sensors may e.g. be embedded in a single small patch, but also in e.g. an larger I- or L-shaped patch which holds the motion sensor on the location of the Atlas device (at the lower left rib) and the sound sensor(s) higher on the chest.

(30) Value segment solutions and connected primary and secondary care are directed to improve the Africa and Asia use-case for pneumonia detection. Because the cost of the device is a prime concern, the motion and the sound functionality may be combined in one single sensor, such as a high bandwidth accelerometer/gyroscope or a low frequency microphone comprising a heavy membrane, e.g. an (almost) DC coupled condenser or electret microphone, air pressure sensor, crystal microphone, etc.

(31) For Hospital-to-Home and home healthcare a hand-held device may be designed, which can be used by a general practitioner, nurse, doctor, or non-medical (but preferably trained) personnel like home caregivers and community healthcare workers, for the diagnosis or follow-up (which preferably requires consistent placement and posture) of, for example, pneumonia, heart failure, and COPD patients.

(32) The present invention may also be embedded in a wearable patch that can be work hospital-to-home for, for example, pneumonia, heart failure, and COPD patients. A wearable patch ensures that regular spot-check measurements are always performed at the same body-location. Performing the measurements in the same posture, and basic knowledge about the patient (e.g. age, height and weight), the motion signals provide a stable approximation for the air flow and volume, and can be reliably used for normalization of the lung sound analysis results. This enables valid trending of the disease progression or healing process.

(33) The combination of motion (accelerometer, gyroscope) and sound signals acquired simultaneously with a sensor package attached to the chest or back can also be used to improve the reliability of fall detection.

(34) For patient monitoring the present invention may also be embedded in a bedside monitor for patients in the emergency department, intensive care unit and operating room, to monitor the presence and extent of pulmonary edema, which is a common complication in patients receiving intravenous fluids (fluid overload). This works for both spontaneously breathing as well as for mechanically ventilated patients, e.g. to guide the weaning process in the ICU.

(35) For home respiratory care the sleep quality is of strong interest in the biomedical imaging unit. The appearance and characteristics (e.g. rate, duration, intensity and nature) of sleep apnea, snoring, and coughing and activity during sleep is important clinical information to gather. The combination of motion sensor(s) and sound sensor(s) attached to the body can thus additionally be used to gather this information in a highly consistent and accurate way. This can be used, for example, to optimize the ventilation therapy (type of ventilator and mask, ventilator settings) and improve sleep position and comfort.

(36) The idea of body sound analysis combined with motion sensing can further be used in additional use scenarios like pre-operative training of surgery patients (e.g. to practice abdominal breathing), alarming (improved fall detection), breath-support training for musicians and singers. When a microphone is present to pick up environmental sounds, even more applications in the field of smart-alarming, bed-leave detection, fall detection, nightmare detection etc. are feasible.

(37) While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims.

(38) In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. A single element or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

(39) A computer program may be stored/distributed on a suitable non-transitory medium, such as an optical storage medium or a solid-state medium supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunication systems.

(40) Any reference signs in the claims should not be construed as limiting the scope.