EP3359029A1 - Dispositif, système et procédé pour obtenir des informations relatives aux signes vitaux d'un être vivant - Google Patents

Dispositif, système et procédé pour obtenir des informations relatives aux signes vitaux d'un être vivant

Info

Publication number
EP3359029A1
EP3359029A1 EP16777692.1A EP16777692A EP3359029A1 EP 3359029 A1 EP3359029 A1 EP 3359029A1 EP 16777692 A EP16777692 A EP 16777692A EP 3359029 A1 EP3359029 A1 EP 3359029A1
Authority
EP
European Patent Office
Prior art keywords
illumination
skin region
unit
vital sign
light
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP16777692.1A
Other languages
German (de)
English (en)
Inventor
Willem VERKRUIJSSE
Gerard De Haan
Andreas Wolfgang SCHLACK
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Koninklijke Philips NV
Original Assignee
Koninklijke Philips NV
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Koninklijke Philips NV filed Critical Koninklijke Philips NV
Publication of EP3359029A1 publication Critical patent/EP3359029A1/fr
Pending legal-status Critical Current

Links

Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/02—Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
    • A61B5/024—Detecting, measuring or recording pulse rate or heart rate
    • A61B5/02416—Detecting, measuring or recording pulse rate or heart rate using photoplethysmograph signals, e.g. generated by infrared radiation
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/0059—Measuring for diagnostic purposes; Identification of persons using light, e.g. diagnosis by transillumination, diascopy, fluorescence
    • A61B5/0062—Arrangements for scanning
    • A61B5/0064—Body surface scanning
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/0059—Measuring for diagnostic purposes; Identification of persons using light, e.g. diagnosis by transillumination, diascopy, fluorescence
    • A61B5/0077—Devices for viewing the surface of the body, e.g. camera, magnifying lens
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/103—Detecting, measuring or recording devices for testing the shape, pattern, colour, size or movement of the body or parts thereof, for diagnostic purposes
    • A61B5/11—Measuring movement of the entire body or parts thereof, e.g. head or hand tremor, mobility of a limb
    • A61B5/1121—Determining geometric values, e.g. centre of rotation or angular range of movement
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/103—Detecting, measuring or recording devices for testing the shape, pattern, colour, size or movement of the body or parts thereof, for diagnostic purposes
    • A61B5/11—Measuring movement of the entire body or parts thereof, e.g. head or hand tremor, mobility of a limb
    • A61B5/113—Measuring movement of the entire body or parts thereof, e.g. head or hand tremor, mobility of a limb occurring during breathing
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/72—Signal processing specially adapted for physiological signals or for diagnostic purposes
    • A61B5/7203—Signal processing specially adapted for physiological signals or for diagnostic purposes for noise prevention, reduction or removal

Definitions

  • the present invention relates to a device, a system and a corresponding method for obtaining vital sign related information of a living being.
  • pulsation of arterial blood causes changes in light absorption.
  • Those changes observed with a photodetector (or an array of photodetectors) form a PPG (photo- plethysmography) signal (also called, among other, a pleth wave).
  • Pulsation of the blood is caused by the beating heart, i.e. peaks in the PPG signal correspond to the individual beats of the heart. Therefore, a PPG signal is a heartbeat signal in itself.
  • the normalized amplitude of this signal is different for different wavelengths, and for some wavelengths it is also a function of blood oxygenation.
  • the image acquisition for challenging cases like strong motion, low light levels, non-white illumination, needs further improvement.
  • biometrical signals such as heartbeat, respiration rate, Sp02 rate, etc.
  • the known methods, systems and devices are generally robust to motion and different lighting environments as long as one dominant light source is present. In such condition the PPG technology has proven to be accurate and robust up to a point that it can be used, at least for some vital signs like heart rate, on a treadmill during fitness exercises.
  • image-based vital signs monitoring occurs when no dominant light is present in the environment. Further, a particular illumination is not always optimal for all measurements, e.g. for different skin types, body postures or after body movements.
  • WO 2014/087310 Al discloses a device and method for obtaining vital sign information of a living being.
  • the disclosed device comprises a detection unit for receiving light in at least one wavelength interval reflected from at least a region of interest of a living being and for generating an input signal from the received light, a processing unit for processing the input signal and deriving vital sign information of said living being from said input signal by use of remote photoplethysmography, an illumination unit for illuminating at least said region of interest with light, and a control unit for controlling said illumination unit based on said input signal and/or said derived vital sign information.
  • a detection unit for receiving light in at least one wavelength interval reflected from at least a region of interest of a living being and for generating an input signal from the received light
  • a processing unit for processing the input signal and deriving vital sign information of said living being from said input signal by use of remote photoplethysmography
  • an illumination unit for illuminating at least said region of interest with light
  • a control unit
  • WO 2013/186696 Al discloses a system for determining a vital sign of a subject, comprising an imaging unit for obtaining video data of the subject, a marker directly or indirectly attached to a body of the subject, wherein the marker comprises a graphical pattern, an image processing unit for detecting said marker in said video data, and an analysis unit adapted to extract a vital sign parameter related to the vital sign of the subject from said video data and to determine the vital sign from said vital sign parameter.
  • a device for obtaining vital sign related information of a living being comprising:
  • an input unit for receiving an input signal generated from light received in at least one wavelength interval reflected from a skin region of a living being, said input signal representing vital sign related information from which a vital sign of the living being can be derived, a processing unit for processing the input signal and deriving vital sign related information of said living being from said input signal,
  • an orientation estimation unit for estimating the orientation of said skin region
  • control unit for controlling an illumination unit for illuminating said skin region with light to illuminate said skin region based on the estimated orientation of said skin region and/or for controlling said processing unit to derive vital sign related information from said input signal obtained during time intervals selected based on the estimated orientation of said skin region.
  • a system for obtaining vital sign related information of a living being comprising
  • a detection unit for receiving light in at least one wavelength interval reflected from a skin region of a living being and for generating an input signal from the received light representing vital sign related information from which a vital sign of the living being can be derived
  • an illumination unit for illuminating said skin region with light
  • a device as disclosed herein for obtaining vital sign related information of a living being from said input signal.
  • a computer program which comprises program code means for causing a computer to perform the steps of the method disclosed herein when said computer program is carried out on a computer, as well as a non-transitory computer-readable recording medium that stores therein a computer program product, which, when executed by a processor, causes the method disclosed herein to be performed.
  • the irradiated surface is bigger when the angle between the surface-normal and the incident light (in particular the incident main ray of light) increases.
  • the irradiance decreases with increasing angle.
  • cleaner raw signals input signals are acquired. This is achieved by controlling the illumination of the skin region (also called region of interest) based on the estimated orientation of the skin region, e.g. with respect to the illumination or to a known reference plane, so that the skin region gets illuminated in an optimized way with respect to the acquisition of information, from which one or more accurate vital signs can be derived in a robust manner.
  • the control is preferably performed such that the illumination is done at angles at which changes in skin orientation have a minimal impact on the irradiated, and consequently also the reflected, light intensity.
  • a corresponding processing unit for processing the input signal is provided.
  • This provides that as an alternative to the illumination control, light from different illumination angles can e.g. be time-multiplexed, and said processing unit may decide which time interval(s) to use for processing and, optionally, vital sign extraction.
  • the interaction of electromagnetic radiation, in particular light, with biological tissue is complex and includes the (optical) processes of (multiple) scattering, backscattering, absorption, transmission and (diffuse) reflection.
  • the term "reflect” as used in the context of the present invention is not to be construed as limited to specular reflection but comprises the afore-mentioned types of interaction of electromagnetic radiation, in particular light, with tissue and any combinations thereof.
  • vitamin sign refers to a physiological parameter of a subject (herein also called living being or person or patient) and derivative parameters.
  • the term “vital sign” comprises blood volume pulse- signal, heart rate (HR) (sometimes also called pulse rate), heart rate variability (pulse rate variability), pulsatility strength, perfusion, perfusion indicator, perfusion variability, Traube Hering Mayer waves, respiratory rate (RR), skin temperature, blood pressure, a concentration of a substance in blood and/or tissue, such as (arterial) blood oxygen saturation or glucose level.
  • HR heart rate
  • RR respiratory rate
  • skin temperature blood pressure
  • a concentration of a substance in blood and/or tissue such as (arterial) blood oxygen saturation or glucose level.
  • vitamin sign generally includes health indications obtained from the shape of the PPG signal (e.g. shape may say something about partial arterial blockage (e.g. shape obtained from PPG signals of the hand gets more sinusoidal when applying a blood-pressure cuff on the arm), or about the skin thickness (e.g.
  • vitamin sign information as used in the context of the present invention comprises the one or more measured vital signs as defined above. Furthermore, it comprises data referring to a physiological parameter, corresponding waveform traces or data referring to a physiological parameter of a time that can serve for subsequent analysis.
  • a skin pixel area means an area comprising one skin pixel or a group of adjacent skin pixels, i.e. a data signal may be derived for a single pixel or a group of skin pixels.
  • said control unit is configured to control the intensity, direction, distribution, and/or illumination angle of at least part of the light emitted by said illumination unit.
  • the corresponding (optimal) parameter of the illumination unit can thus be appropriately controlled.
  • other (additional or alternative) parameters may be used for the control, such as the uniformity of illumination in the ROI, good/stable illumination in all relevant channels (wavelengths), no shadow in the ROI, etc.
  • only particular wavelengths are modified (e.g. the wavelength used for vital signs extraction) whereas other wavelengths (e.g. for orientation measurement) remain unaffected.
  • said orientation estimation unit is configured to estimate the orientation of the surface-normal of said skin region
  • said control unit is configured to control the intensity, direction, distribution, and/or illumination angle of at least part of the light emitted by said illumination unit such that most or all light is emitted from an illumination angle closest or identical to the estimated surface-normal.
  • this embodiment minimizes the amplitude of the variation in irradiance by illuminating the skin region at an angle substantially perpendicular to the average skin orientation of a region of interest (ROI), or at least prevents large angles, e.g. larger than 45 degrees. This reduces the variance in irradiance (noise) due to subject movements and thus leads to more robust and accurate input signals and, consequently, vital signs derived therefrom.
  • ROI region of interest
  • said orientation estimation unit is configured to regularly or continuously estimate the orientation of said skin region and wherein said control unit is configured to adjust the control of the illumination unit accordingly. In this way, movements of the subject can be quickly or even immediately recognized so that the illumination can be adapted accordingly in an automated manner.
  • control unit controls the illumination unit based on the estimated orientation of the skin region
  • control unit is configured to control said illumination unit to illuminate said skin region in subsequent time intervals from different illumination angles and to control said processing unit to derive vital sign related information from said input signal obtained during time intervals selected based on the estimated orientation of said skin region.
  • the illumination is e.g. time multiplexed and only the processing is controlled to use only input signals acquired at certain time intervals at which the illumination has be made from the best illumination angle.
  • said illumination unit comprises two or more illumination elements (also called light sources), e.g. a plurality of LEDs.
  • said two or more illumination elements are preferably arranged at different locations and/or with different orientations for illuminating a skin region from different illumination angles.
  • Said two or more illumination elements are preferably controlled individually and may e.g. be LEDs, laser diodes, conventional light bulbs, neon lights, etc. which can be controlled.
  • the control unit is preferably configured to individually control said illumination elements, in particularly to individually control the intensity of the illumination elements. This allows, for instance, to increase the power of the illumination elements that illuminate the skin region at an angle closest to the surface-normal and to decrease the power of the illumination elements that illuminate the skin region at larger angle(s).
  • control unit is configured to control said illumination elements to illuminate said skin region in a multiplexed and/or modulated manner
  • said detection unit is configured to subsequently receive light reflected from said skin region in response to said subsequent illuminations and to generate reflection signals from the received light
  • said orientation estimation unit is configured to determine the reflection signal with the highest intensity.
  • Said control unit is further configured to control said illumination unit such that the illumination element, whose illumination resulted in the reflection signal with the highest intensity, illuminates said skin region exclusively or with the highest intensity among all illumination elements and/or to control said processing unit to derive vital sign related information from said input signal obtained during time intervals, during which the illumination element, whose illumination resulted in the reflection signal with the highest intensity, illuminates said skin region exclusively or with the highest intensity among all illumination elements.
  • the illumination unit (comprising one or more illumination elements) emits a spectrum comprising a wavelength used for orientation and wavelength used for vital signs measurement.
  • the spectrum of the illumination unit may be changed, i.e. only the intensity of the wavelength used for vital sign measurement may be adapted, while optionally the wavelength used for orientation measurement may be kept at the same level. This provides the advantage that the orientation measurement is not suffering from reduced intensity in some directions.
  • control unit is configured to control said illumination elements to pairwise illuminate said skin region, wherein different pairs of neighboring illumination elements alternately illuminate said skin region with different alternation frequencies, with different wavelengths, at different times and/or with a synchronized flickering, said detection unit is configured to subsequently receive light reflected from said skin region in response to said alternate illuminations and to generate reflection signals from the received light, said orientation estimation unit is configured to determine the reflection signal with the smallest intensity modulation.
  • Said control unit is further configured to control said illumination unit such that the pair of illumination elements, whose illumination resulted in the reflection signal with the smallest intensity modulation, illuminates said skin region exclusively or with the highest intensity among all illumination elements or such that only illumination in time slots with illumination that resulted in the reflection signal with the smallest intensity modulation is used for illumination of said skin region or such that only illumination in time slots with illumination that resulted in the reflection signal with the smallest intensity modulation is used for illumination of said skin region and/or to control said processing unit to derive vital sign related information from said input signal obtained during time intervals, during which the pair of illumination elements, whose illumination resulted in the reflection signal with the smallest intensity modulation, illuminates said skin region exclusively or with the highest intensity among all illumination elements.
  • said detection unit comprises a camera for generating said input signal from light received by the camera and a photodiode for generating said reflection signals from light received by the photodiode
  • said illumination unit comprises a first set of illumination elements for illuminating said skin region to enable the generation of input signals by said camera and a second set of illumination elements for illuminating said skin region to enable the generation of reflection signals by said
  • the photodiode From the input signals the vital sign information is then derived, whereas from the reflection signals the orientation of the skin region is estimated.
  • the photodiode allows higher modulation frequencies so that the light reflected from the skin may be focused to a larger extent.
  • the illumination elements of said second set are configured to illuminate said skin region with light of a wavelength or wavelength range outside the sensitivity interval of said camera so that orientation estimation and acquisition of light for the generation of input signals can be done simultaneously with disturbing each other.
  • the orientation estimation unit may be configured to process distance data, in data, in particular time-of-flight (TOF) data as e.g. acquired by a TOF camera or a radar unit, and to determine a 3D model of the skin surface including said skin region. This provides another simple option to estimate the orientation of the skin region in a rather precise manner.
  • TOF time-of-flight
  • said detection unit preferably comprises two or more detection elements.
  • Said detection elements are, for instance, image sensors, video camera, RGB camera, infrared camera or still image cameras. While the detection elements generally have identical parameters but are located at different positions and/or with different orientations, in an embodiment the detection elements are different and/or have different parameters so that the detection element resulting in the best vital sign information can be selected for signal evaluation. In still another embodiment the input signals from two or more detection elements may be commonly evaluated, e.g. after averaging the input signals.
  • Fig. 1 shows a diagram illustrating illumination of a skin surface at different orientations of the skin surface
  • Fig. 2A shows an enlarged portion of the skin surface
  • Fig. 2B shows a diagram illustrating the effect of the illumination of a skin surface at different orientations of the skin surface
  • Figs. 3A and 3B show diagrams illustrating the effect of different skin orientation on pulsatility
  • Fig. 4 shows a diagram illustrating the effect of the present invention
  • Fig. 5 shows a schematic diagram of a first embodiment of a system according to the present invention
  • Fig. 6 shows a schematic diagram of a second embodiment of a system according to the present invention
  • Fig. 7 shows a schematic diagram of a third embodiment of a system according to the present invention.
  • Fig. 8 shows a schematic diagram of a fourth embodiment of a system according to the present invention.
  • Fig. 9 shows an embodiment of a method according to the present invention. DETAILED DESCRIPTION OF THE INVENTION
  • Fig. 1 shows a diagram illustrating illumination of a skin surface at different orientations of the skin surface.
  • a light source 1 with constant location and radiance (W/sr "1 ) provides illumination on skin 2 (in this example the chest wall) of a subject 3 at an angle different from 0° with respect to the normal of the skin.
  • This has the effect that the angle ⁇ , defined as the angle of the normal Ni and N 2 , respectively, with respect to the direction of the illumination 4 varies between ⁇ and ⁇ 2 .
  • Such changes of the orientation of the skin can, despite motion tracking, significantly impact the PPG signal quality, particularly if the illumination onto the skin is at a large angle with the skin surface-normal. This is because the projected light energy is distributed over a surface, the size of which depends on the angle ⁇ between skin surface- normal and illumination. For illumination from a certain solid angle, the irradiated surface is bigger when the angle between the surface-normal and the incident ray increases, hence the irradiance (W/m 2 ) decreases with increasing angle.
  • Fig. 2B shows a diagram illustrating the effect of the illumination of a skin surface at different orientations of the skin surface.
  • Fig. 2A shows an enlarged portion of the skin 2
  • Fig. 2B shows a diagram of the irradiance I (in W/cm 2 ) over the angle ⁇ .
  • the irradiance of the skin that is illuminated is largest for the surface area S p , perpendicular to the direction of illumination 4.
  • the diffuse radiance (light emitted from the skin) will vary and possibly obfuscate the true PPG signal which is of interest for vital signs measurements such as HR, RR, and Sp02.
  • the reflected light shows pulse-frequent intensity variations, as shown in the diagrams depicted in Figs. 3A and 3B.
  • Fig. 3A shows a diagram illustrating the effect of different skin orientations
  • Fig. 3B shows a diagram of the relative pulsatility P (in %) over the angle ⁇ .
  • a periodic orientation change over 1° of the skin surface gives a negligible pulsatility of the reflected light for perpendicular illumination, but rapidly increases for angles above 45°.
  • the surface Ri also called Lambertian surface
  • the surface R 2 is arranged at an angle a 2 ⁇ 90° to the incident light so that a larger area A 2 > Ai is illuminated with lower luminance.
  • the present invention minimizes the amplitude of the variation in irradiance by adapting the angle of illumination of the skin.
  • the angle of illumination is controlled such that it is substantially perpendicular to the average skin orientation of a region of interest (ROI), or as close as possible to this perpendicular direction.
  • at least illumination from large angles ⁇ e.g. larger than 45 degrees are prevented.
  • Fig. 4 shows particularly the angle ⁇ over time t, the irradiance I over time t and the irradiance I over the angle ⁇ , all for three different angles of irradiation (or lamp positions called positions A, B and C).
  • the irradiance is highly periodic due to the periodic changes in skin orientation.
  • the periodicity in irradiance is somewhat mitigated, i.e. the temporal variation is smaller and the overall irradiance level is higher than at position A.
  • the impact of the skin orientation is minimized. Further, the variation in irradiance is strongly diminished and, in addition, the frequency has doubled.
  • Fig. 5 shows a schematic diagram of a first embodiment of a system 100 for obtaining vital sign related information of a living being 3 according to the present invention.
  • the system 100 comprises a detection unit 30, e.g. a camera, for receiving light 31 in at least one wavelength interval reflected from a skin region 2 (e.g. here the chest wall; other areas may be a hand, an arm, the belly area, the forehead, the check, etc.) of a living being 3 and for generating an input signal 32 from the received light 31 representing vital sign related information from which a vital sign of the living being can be derived.
  • An illumination unit 40 e.g. comprising two or more light sources (e.g. LEDs) 42 illuminates said skin region 2 with light 41.
  • An orientation estimation unit 16 estimates the orientation 26 of said skin region 2, for which step various options exist as will be explained below in more detail.
  • a control unit 18 controls said illumination unit 40 by a control signal 28 based on the estimated orientation 26 of said skin region 2.
  • the orientation estimation unit 16 and the control unit 18 may be part of a separate device 10, which, in this embodiment, comprises an input unit 12, e.g. a signal interface, for receiving the input signals 32 from the detection unit 30. Further, the device 10 may comprise a processing unit 14 for processing the input signal 32 and deriving vital sign information 36 of said living being 3 from said input signal 32, preferably by use of photoplethysmography.
  • an input unit 12 e.g. a signal interface
  • the device 10 may comprise a processing unit 14 for processing the input signal 32 and deriving vital sign information 36 of said living being 3 from said input signal 32, preferably by use of photoplethysmography.
  • One or more units of the device 10 may also be comprised in one or multiple digital or analog processors depending on how and where the invention is applied.
  • the different units may completely or partly be implemented in software and carried out on a personal computer connected to one or more detectors. Some or all of the required functionality may also be implemented in hardware, e.g. in an application specific integrated circuit (ASIC) or in a field programmable gate array (FPGA).
  • ASIC application specific integrated circuit
  • FPGA field programmable gate array
  • a system 100 as illustrated in Fig. 5 may, e.g., be located in a hospital, healthcare facility, elderly care facility or the like. Apart from the monitoring of patients, the present invention may also be applied in other fields such as neonate monitoring, general surveillance applications, security monitoring or so-called live style environments, such as fitness equipment, or the like.
  • the uni- or bidirectional communication between the device 10, the detection unit 30 and the illumination unit 40 may work via a wireless or wired communication.
  • Other embodiments of the present invention may include a device 10, which is not provided as a stand-alone device, but one or more elements of the device 10, e.g. the orientation estimation unit 16 and the control unit 18, may be integrated into the detection unit 30 or the illumination unit, and the processing unit 14 may be integrated into another device, such as a workstation at a nurse station or integrated into a hospital network.
  • the interaction of electromagnetic radiation, in particular light, with biological tissue is complex and includes the (optical) processes of (multiple) scattering, backscattering, absorption, transmission and (diffuse) reflection.
  • the term "reflect” as used in the context of the present invention is not to be construed as limited to specular reflection but comprises the afore-mentioned types of interaction of electromagnetic radiation, in particular light, with tissue and any combinations thereof.
  • vitamin sign refers to a physiological parameter of a subject (i.e. a living being) and derivative parameters.
  • the term “vital sign” comprises blood volume pulse signal, heart rate (HR) (sometimes also called pulse rate), heart rate variability (pulse rate variability), pulsatility strength, perfusion, perfusion indicator, perfusion variability, Traube Hering Mayer waves, respiratory rate (RR), skin temperature, blood pressure, a concentration of a substance in blood and/or tissue, such as (arterial) blood oxygen saturation or glucose level.
  • HR heart rate
  • RR heart rate variability
  • pulsatility strength perfusion
  • perfusion indicator perfusion variability
  • RR respiratory rate
  • skin temperature blood pressure
  • a concentration of a substance in blood and/or tissue such as (arterial) blood oxygen saturation or glucose level.
  • RR respiratory rate
  • skin temperature e.g. shape may say something about partial arterial blockage (e.g. shape obtained from PPG signals of the hand gets more sinusoidal when applying a blood-pressure cuff on
  • vitamin sign related information comprises information, from which one or more vital signs as defined above can be derived. Furthermore, it comprises data referring to a physiological parameter, corresponding waveform traces or data referring to a physiological parameter of a time that can serve for subsequent analysis.
  • the detection unit 30 comprises a camera (also referred to as imaging unit, or as camera-based or remote PPG sensor) including a suitable photosensor for (remotely and unobtrusively) capturing image frames of the subject 3 (at least of the skin region 2, in particular for acquiring a sequence of image frames over time, from which photoplethysmography signals can be derived.
  • the image frames captured by the camera may particularly correspond to a video sequence captured by means of an analog or digital photo-sensor, e.g. in a (digital) camera.
  • Such a camera usually includes a photo-sensor, such as a CMOS or CCD sensor, which may also operate in a specific spectral range (visible, IR) or provide information for different spectral ranges.
  • the camera may provide an analog or digital signal.
  • the image frames include a plurality of image pixels having associated pixel values. Particularly, the image frames include pixels representing light intensity values captured with different photosensitive elements of a photo-sensor.
  • photosensitive elements may be sensitive in a specific spectral range (i.e. representing a specific color).
  • the image frames include at least some image pixels being representative of a skin portion of the subject.
  • an image pixel may correspond to one photosensitive element of a photo-detector and its (analog or digital) output or may be determined based on a combination (e.g. through binning) of a plurality of the photosensitive elements.
  • a skin pixel area means an area comprising one skin pixel or a group of adjacent skin pixels, i.e. a data signal may be derived for a single pixel or a group of skin pixels.
  • the illumination unit 40 in this embodiment comprises at least two
  • illumination elements 42 i.e. light sources such as LEDs or other light emitting elements.
  • the orientation estimation unit 16 determines which of these at least illumination elements 42 emits its light closest along the skin-surface-normal (or closest to the surface-normal of the largest part of the skin-surface should the skin surface not be flat). Once this illumination element has been established, the other illumination elements are e.g. dimmed or switched off completely so that the movement induced signals reflected from the skin are minimized in the input signal 32 (and in a PPG signal derived therefrom) conveyed in the light 31 (diffusely) reflected from the skin.
  • the image data acquired by the camera representing the detection unit 30 in the system 100 may be used to determine (sequentially) which of the illumination elements 42 radiates closest along the surface-normal of the skin.
  • the illumination element that produces the highest illumination is assumed best for that (portion of) skin (and, optionally, used for the actual vital signs determination in the optional processing unit 14, for which purpose the orientation estimation unit 16 informs the processing unit 14 accordingly).
  • these steps representing a kind of calibration, may be repeated to adaptively control the illumination, in particular the angle of illumination of the skin region 2.
  • the illumination unit 40 may generally be configured as a one- or two- dimensional array of illumination elements 42.
  • the illumination elements 42 may be arranged at a flat or slightly curved frame.
  • the illumination elements 42 can be individually controlled.
  • control unit 18 is configured to control the intensity, direction, distribution, and/or illumination angle of the light emitted by the illumination unit 40.
  • Fig. 6 shows a schematic diagram of a second embodiment of a system 101 according to the present invention.
  • an additional distance data acquisition unit 50 is provided to acquire distance data 52 representing the distance between the distance data acquisition unit 50 and the skin region 2 by use of radiation 51 emitted to and reflected back from the subject.
  • the distance data acquisition unit 50 may e.g. be a time-of-flight (TOF) camera or a radar unit.
  • TOF time-of-flight
  • the orientation estimation unit 16 can determine the orientation of the skin surface of the skin region 2 or can generate a 3D model of the skin surface of the skin region 2. This provides another simple option to estimate the orientation of the skin region in a rather precise manner.
  • other methods to establish the 3D model may be employed in other embodiments.
  • Said illumination unit 60 comprises a single illumination element 61 and a shutter element 62 comprising (mechanically or electronically) switchable shutters for allowing or preventing the passage of light from different areas of the illumination element 61.
  • a shutter element 62 comprising (mechanically or electronically) switchable shutters for allowing or preventing the passage of light from different areas of the illumination element 61.
  • an LCD may be used as illumination element 61 together with an array of individually controllable shutters (i.e. controlled by the control signal 26) between the light emitting element 61 and the subject 3.
  • Such an illumination unit 60 can also be used in other embodiments of the proposed system, e.g. the system 101 shown in Fig. 5, and an illumination unit 40 can also be used in the embodiment of system 101 shown in Fig. 6.
  • the skin is not an ideal Lambertian reflector, i.e. also produces specular reflection or reflectance not along the Lambertian 'cosine law'.
  • This model can particularly be useful if shorter wavelengths are used for which the diffuse reflection can be quite absorbed. In this case the camera can see the highest luminance from the
  • two neighboring illumination elements 42 of the plurality of illumination elements 42 of the illumination unit 40 are alternatingly emitting light of equal strength (but under a slightly different angle to the surface-normal). Pairs of illumination elements 42 at different location in the illumination unit 40 alternate at different frequencies.
  • the light 31 reflected from the skin 2 now shows all different frequency components, in particular all different frequency components, but the illumination elements 42 that emit closest to the surface-normal will give the lowest frequency amplitude. Consequently from the (modulation) spectrum of the reflected light 31 it can be determined, which orientation of an illumination element 42 is closest to the surface-normal.
  • the spectrum may be measured with the camera pointed at the skin region 2, but higher modulation frequencies are likely possible with a photodiode to which the skin-reflected light is focused.
  • a further alternative is to run the camera at a higher speed (often possible at a lower resolution, the so-called "binning" option of the camera).
  • Fig. 7 shows a schematic diagram of a third embodiment of a system 102 according to the present invention.
  • the detection unit 30 comprises a camera 33 for generating said input signal 32 from light 31 received by the camera 33 and a photodiode 34 for generating reflection signals 35 from light 31 received by the photodiode 34.
  • the illumination unit 40 comprises a first set 43 of illumination elements 44 for illuminating said skin region 2 to enable the generation of input signals 31 by said camera 33 and a second set 45 of illumination elements 46 for illuminating said skin region 2 to enable the generation of reflection signals 35 by said photodiode 34.
  • the wavelengths used by the first set 43 of illumination elements are the wavelengths used by the first set 43 of illumination elements.
  • the illumination elements 46 are configured to illuminate said skin region 2 with light of a wavelength or wavelength range outside the sensitivity interval of said camera 33. Further, the number of illumination elements 44 and illumination elements 46 may differ.
  • Two neighboring illumination elements may also be separated through other means than modulation frequencies, such as the use of slightly different wavelengths, sequential illumination, synchronized flickering at the same frequency, etc.
  • control unit 18 controls the illumination unit 40 based on the estimated orientation of the skin region 2.
  • control unit 18 may, additionally or alternatively, control the processing unit 14 based on the estimated orientation of the skin region 2.
  • the processing unit 14 may be controlled to derive vital sign related information 36 from the input signal obtained during time intervals selected based on the estimated orientation of said skin region, i.e. during time intervals during which the skin region is optimally illuminated. This is illustrated in Fig. 7 by the control signal 29 from the control unit 18 to the processing unit 14, but may also be provided in other embodiments.
  • the illumination unit may illuminate the skin region 2 continuously in the same manner, optionally without additional control.
  • Fig. 8 shows a schematic diagram of a fourth embodiment of a system 103 according to the present invention, wherein the elements of the device 10 are not explicitly shown.
  • the illumination unit and the detection unit are embedded into a radiant warmer 60. Babies are often kept in such a radiant warmer 60 to help keeping the temperature of the baby regulated. This gives better access to the baby for treatment, care and procedures.
  • a radiant warmer 60 normally has an IR warming lamp 62 centered above the baby 2.
  • the means to hold the heating element 62 makes it also the ideal place to integrate the detection unit 30, here in the form of a camera as explained above, frontend along with this heating element 62 at the same spot as much as space allows.
  • the arm 63 that carries the heating element 62 can also carry the camera 30 inside (basically invisible as it only need a little hole). Further, the arm contain the illumination elements 42 of the illumination unit 40, here in the form of an array around the camera 30. Cable routing can be managed there perfectly inside the warmer 60, in particular the arm 63.
  • the device 10 may also be integrated in the radiant warmer 60. Further, the radiant warmer 60 may share a user interface and any further potential computation means that may be required for the monitoring and the warming functions. In a similar way some or all elements of the proposed system may be integrated into an incubator.
  • FIG. 9 A flowchart of an embodiment of a method according to the present invention is shown in Fig. 9.
  • a first step S10 at least a skin region 2 of a living being 3 is illuminated with light.
  • a second step S12 light 31 in at least one wavelength interval reflected from said skin region 2 is received.
  • an input signal 32 is generated from the received light 31 representing vital sign related information from which a vital sign of the living being can be derived.
  • the input signal 32 is processed to derive vital sign information 36 of said living being from said input signal 32.
  • the orientation of said skin region 2 is estimated.
  • said illumination unit 40 based on the estimated orientation of said skin region 2 to illuminate said skin region 2 and/or said processing to derive vital sign related information 36 based on the estimated orientation of said skin region.
  • vital signs measurement devices derive vital sign information by measuring the subtle change in the skin area of the region of interest, which in turn relies on the illumination.
  • a dedicated illumination is needed.
  • one particular pre-set illumination might not always be optimal for measurement.
  • specular reflection is one of the difficulties, in particular for Sp02 measurement, which should be avoided in the region of interest (ROI) used for measurement. Due to different skin types (conditions) and body postures or after body movement, specular reflections might exist or appear in the ROI. Manually adjusting illumination setup for each measurement, or after each change in the environment or the vital signs measurement device, is subjective and time consuming.
  • the present invention proposes an adaptive device and method for unobtrusive vital signs measurement (e.g. heartbeat monitoring, Sp02 monitoring, etc.), which can be automatically configured for optimal measurement.
  • a control unit is provided that controls said illumination unit, e.g. one or more controllable light sources, and/or the processing unit for deriving vital signs related information, e.g. a vital sign itself or a signal from which a vital sign can be derived, based on the estimated orientation of the skin surface.
  • vital signs related information e.g. a vital sign itself or a signal from which a vital sign can be derived
  • the present invention may be applied in various applications.
  • Heart rate, respiration rate, and Sp02 are very relevant factors in patient monitoring and home- healthcare where remote heart rate monitoring becomes more and more relevant.
  • the present invention may be applied to register heartbeat in fitness devices.
  • the proposed invention can particularly be applied in any application where (contactless) camera-based vital signs monitoring is performed with controllable illumination that is changing or with variable light conditions. Typical application areas are e.g. premature babies with very sensitive skin in NICUs and patients with damaged (e.g. burns) skin. Locations of application include NICU, emergency waiting room, general ward, nursing homes, home healthcare, and psychiatric ward/prison. Normally, the vital signs extraction is extremely challenging and even impossible in some cases, but can now be accurately and reliably achieved. Further, the present invention can be applied in contact PPG device, such as contact pulse oximeters or fingerclip sensors for Sp02 measurement.
  • 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.
  • 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.

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Abstract

La présente invention concerne un dispositif, un système et un procédé pour obtenir des informations relatives aux signes vitaux d'un être vivant (3). Le dispositif de l'invention comprend une unité d'entrée (12) pour recevoir un signal d'entrée (32) généré à partir d'une lumière (31) reçue dans au moins un intervalle de longueur d'onde et réfléchie depuis une région de peau (2) d'un être vivant (3), ledit signal d'entrée représentant des informations relatives aux signes vitaux à partir desquelles un signe vital de l'être vivant peut être obtenu, une unité de traitement (14) pour traiter le signal d'entrée (32) et obtenir des informations relatives aux signes vitaux (36) dudit être vivant à partir dudit signal d'entrée (32), une unité d'estimation d'orientation (16) pour estimer l'orientation de ladite région de peau (2), et une unité de commande (18) pour commander une unité d'éclairage (40) pour éclairer ladite région de peau (3) avec la lumière (41) pour éclairer ladite région de peau (2) sur la base de l'orientation estimée de ladite région de peau (2) et/ou pour commander ladite unité de traitement pour obtenir des informations relatives aux signes vitaux (36) à partir dudit signal d'entrée obtenu pendant des intervalles de temps sélectionné sur la base de l'orientation estimée de ladite région de peau (2).
EP16777692.1A 2015-10-06 2016-10-06 Dispositif, système et procédé pour obtenir des informations relatives aux signes vitaux d'un être vivant Pending EP3359029A1 (fr)

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US201562237737P 2015-10-06 2015-10-06
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PCT/EP2016/073862 WO2017060342A1 (fr) 2015-10-06 2016-10-06 Dispositif, système et procédé pour obtenir des informations relatives aux signes vitaux d'un être vivant

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CN118076301A (zh) * 2021-11-05 2024-05-24 松下知识产权经营株式会社 摄像系统、处理装置及在摄像系统中由计算机执行的方法

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CN108135515A (zh) 2018-06-08
RU2018116893A (ru) 2019-11-07
BR112018006813A2 (pt) 2018-10-16
MX2018004088A (es) 2018-07-06
WO2017060342A1 (fr) 2017-04-13
JP2018534025A (ja) 2018-11-22

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