Device, system and method for detecting apnoea of a subject
First Claim
1. A medical monitor device for detecting apnoea of a subject, comprising:
- a video camera configured to monitor the subject and generate image data indicative thereof, said image data including a sequence of images over time,an input unit for receiving the image data of subject from the video camera,a cardiac activity extraction unit for extracting from said image data a cardiac activity signal representing the subject'"'"'s cardiac activity from a skin area of the subject using remote photoplethysmography,a motion signal extraction unit for extracting from said image data a motion signal representing motion of a subject'"'"'s body part caused by breathing of the subject,an analysis unit for determining the similarity between said cardiac activity signal and said motion signal, anda decision unit for detecting apnoea of the subject based on the determined similarity, and generating an apnoea warning signal in response to detecting the apnoea,wherein the motion signal represents motion of the subject'"'"'s body part caused by the breathing of the subject and motion of the subject'"'"'s body part caused by cardiac activity of the subject such that the motion signal has a fundamental frequency of a respiratory rate of the subject when the subject is breathing and has a fundamental frequency of a heart rate of the subject during apnoea, and whereinduring apnoea, the cardiac activity signal and the motion signal have a higher similarity, andwhen the subject is breathing normally, the similarity between the cardiac activity signal and the motion signal is lower.
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Accused Products
Abstract
A device, system and method unobtrusively and reliably detect apnoea of a subject (2). An input unit (11) receives image data of subject. The image data includes a sequence of images over time. A cardiac activity extraction unit (12) extracts from the image data a cardiac activity signal representing the subject'"'"'s cardiac activity from a skin area of the subject using remote photoplethysmography. A motion signal extraction unit (14) extracts from said image data a motion signal representing motion of a subject'"'"'s body part caused by breathing of the subject. An analysis unit (16) determines a similarity between said cardiac activity signal and said motion signal. A decision unit (18) detects apnoea of the subject based on the determined similarity.
41 Citations
17 Claims
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1. A medical monitor device for detecting apnoea of a subject, comprising:
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a video camera configured to monitor the subject and generate image data indicative thereof, said image data including a sequence of images over time, an input unit for receiving the image data of subject from the video camera, a cardiac activity extraction unit for extracting from said image data a cardiac activity signal representing the subject'"'"'s cardiac activity from a skin area of the subject using remote photoplethysmography, a motion signal extraction unit for extracting from said image data a motion signal representing motion of a subject'"'"'s body part caused by breathing of the subject, an analysis unit for determining the similarity between said cardiac activity signal and said motion signal, and a decision unit for detecting apnoea of the subject based on the determined similarity, and generating an apnoea warning signal in response to detecting the apnoea, wherein the motion signal represents motion of the subject'"'"'s body part caused by the breathing of the subject and motion of the subject'"'"'s body part caused by cardiac activity of the subject such that the motion signal has a fundamental frequency of a respiratory rate of the subject when the subject is breathing and has a fundamental frequency of a heart rate of the subject during apnoea, and wherein during apnoea, the cardiac activity signal and the motion signal have a higher similarity, and when the subject is breathing normally, the similarity between the cardiac activity signal and the motion signal is lower. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A medical monitor for detecting apnoea of a subject, comprising:
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a video camera for generating image data of the subject, said image data including a sequence of images over time, an input unit for receiving the image data, a cardiac activity extraction unit for extracting from the received image data a cardiac activity signal representing cardiac activity of the subject from a skin area of the subject using remote photoplethysmography, a motion signal extraction unit for extracting from said received image data a motion signal representing motion of a subject'"'"'s body part caused by breathing of the subject, an analysis unit configured to determine a similarity between said cardiac activity signal and said motion signal by; comparing fundamental frequencies present in said cardiac activity signal and said motion signal, and determining a Euclidian distance between the fundamental frequencies, a ratio between the fundamental frequencies and/or an energy ratio of the fundamental frequencies, in particular at the heart rate frequency, and a decision unit for detecting apnoea of the subject based on the determined similarity and outputting an apnoea warning in response to detecting the apnoea.
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12. A method of monitoring for apnoea in a subject, comprising:
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receiving video image data of subject, said image data including a sequence of images over time, the images of the sequence each including (i) a skin area which changes color with cardiac activity and (ii) a body region which moves with respiration and cardiac motion, extracting from said video image data a cardiac activity signal representing the subject'"'"'s cardiac activity from the skin area of the subject using remote photoplethysmography, extracting from said video image data a motion signal representing motion of the body region caused by breathing and cardiac activity of the subject, wherein during apnoea, the cardiac activity dominates the motion signal, determining a similarity measure between said cardiac activity signal and said motion signal indicating occurrence of apnoea of the subject when the similarity measure exceeds a predetermined threshold, in response to the motion signal indicating the occurrence of apnoea, generating an apnoea warning, wherein the motion signal represents motion of the subject'"'"'s body part caused by the breathing of the subject and motion of the subject'"'"'s body part caused by cardiac activity of the subject, such that when the subject stops breathing, the motion signal represents cardiac activity. - View Dependent Claims (13)
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14. A monitor for monitoring a subject for apnoea, comprising:
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a camera configured to generate a sequence of images of at least a skin area and a body part area of the subject over time; one or more computer processors configured to; from a first portion of the images of the sequence corresponding to the skin area of the subject, extracting a cardiac activity signal using remote photoplethysmography, the cardiac activity signal representing cardiac activity of the subject; from a second portion of the images of the sequence of images corresponding to the body part area of the subject, extracting a motion signal representing motion of the body part area of the subject, the motion signal representing breathing and cardiac activity motion of the body part area of the subject; determining a similarity measure between the cardiac activity signal and the motion signal over time; comparing the similarity measure with a threshold; and in response to the similarity measure meeting or exceeding the threshold, controlling an apnoea indicating device to indicate apnoea of the subject, wherein when the subject is breathing normally, the breathing motion dominates the motion signal and when the subject undergoes apnoea, the motion signal is dominated by the cardiac activity motion, and wherein when the cardiac activity motion dominates the motion signal, the similarity measure between the motion signal and the cardiac activity is high, and wherein when the subject is breathing normally, the motion signal is dominated by the breathing of the subject and the similarity measure is low. - View Dependent Claims (15, 16, 17)
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Specification