System and method for determining a vital sign of a subject.

(54) Title: SYSTEM AND METHOD FOR DETERMINING A VITAL SIGN OF A SUBJECT. (54) Title: SYSTEM AND METHOD FOR DETERMINING A VITAL SIGN OF A SUBJECT.

(57) Summary

The present invention relates to a system (1,1 ', 1) for determining a vital sign of a subject (100) by means of which the probability of generating and sending false alarms is reduced. The system comprises a vital sign processor (30, 30a) to process the vital sign information signal measured by a sensor (10,10 ', 10a, 10b) attached to a subject to obtain a vital sign from the subject, a unit analysis unit (50) to detect the movement of a marker (20, 20 ', 20a, 20b) attached to the sensor from image data obtained by a graphics display unit (40) from at least one graphic display region containing the sensor (10,10 ', 10a, 10b) and an alarm unit ( 60) to generate and send an alarm signal based on the measured vital sign information signal and / or the obtained vital sign and on the detected movement of the marker.

(57) Abstract

The present invention relates to a system (1, Γ, 1) for determining a vital sign of a subject (100) by which the likelihood of generating and outputting false alarms is reduced. The system comprises a vital sign processor (30, 30a) for processing said vital sign Information signal measured by a sensor (10, 10 ', 10a, 10b) attached to a subject to obtain a vital sign of said subject, an image analysis unit (50) for detecting motion of a marker (20, 20 ', 20a, 20b) attached to said sensor from image data obtained by an imaging unit (40) from at least an imaging region containing said sensor (10,10', 10a , 10b), and an alarm unit (60) for generating and outputting an alarm signal based on the measured vital sign Information signal and / or obtained vital sign and on the detected motion of said marker.

IMPI

<img file="MX355772B_D0001.tif" />

PATENT TITLE No. 355772

Headlines):

Home:

Denomination:

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Inventor (s):

KONINKLIJKE PHILIPS NV

High Tech Campus 5, NL-5656, AE Eindhoven, NETHERLANDS

SYSTEM AND METHOD FOR DETERMINING A LIFE SIGN OF A SUBJECT.

CIP: A61B5 / 0295; A61B5 / 00; A61B5 / 11; A61B5 / 024; A63B24 / 00

CPC: A61B5 / 746; A61 B5 / 0Í (¿; Α6ΐβ5 / 02ϊ A61B5 / 021; A61B5 / 0205; A61B5 / 0295;

A6165 / 1127r Αβ1 B5 / 02416; Á61 B§ / Í2 &lt;F1; A61B5 / 14551

ERIK BRESCH; JENS MÜHLST ^ BE, „.

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Number:

MX / a / 2015/010349

Country:

US

EP

Validity: Twenty years:

Expiration Date: February 7, 2034 Issue Date: 30 ahj # d &amp; 2018 ,,

International:

, í5 &lt;jéfebrerg ^ 2 ^ 3 VM r; ΐ and

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Number:

61/7(55,096

131S5430.5

The patent of reference with the original foundations *!,? ír ^ i ^^^ lúdela Üeyde de la Prp ^ epfoJ Industrial.

In accordance with artira ^ 23 4e the Law of ta f? Ropt ed »&lt;flná (b« «W ·« Mfhte (Aer ^ rfrwfávigertítde verte Mrftapn from the filing date of the application mtémacaonSly will be subject pagQele fftirififSBWMne «ener vigen» SjR &lt;Brec

Whoever subscribes to the present title, heeei (c0, fun &lt;¿ifienteaen lo arranged.pór (Wahicul ^ s f5 “fractions III and ^ 'MsÉ.ste the Industrial Property Law (Official Gazette of the Federation (&amp; OF.) / 06/1991 reformed the K «á | 994, ®1Κ &lt;Μ% 26/12 /»

01/25/2006, 05/06/2009, 06/01/2010, ^^ * 6 / ^ 0, ^ / 06 / ¾¾) ^ / φ / φΐ2 MSm / 20t2 | adieoís # l^or, 3ttfi Regulations of the Mexican Institute ae1SflWj> iJgl¡ad ItHEstaal ®g, Wormad¿jel 01 / &

articles 1 °, 3 ”, 4 °, 5 ° fraction V subsection 30 d§ ^ 8turoOrgág) dg ^ jt3Bt» itú (dJi¡1exicano de la Propiedad Industrial (DOF

12/27/1999, amended on 10/10/2002, 07/29 / 2Ó0 ^ ¡MÍtoOT4 AraWdo that delegates powers to the Directors

Deputy Generals, Coordinator, Director s DivÜrfí ^ íT ^ lulae ^ SeAaíftjPnS6¿i> ^ jÍBrt¡atee, Divisional Deputy Directors, Departmental Coordinators and other subordinates of the Mexican Institute »la ^^^^ lMt ^^ íltriaf. '^ II ^^ F 15 / 12/1999, amended on 02/04/2000, 07/29/2004, 08/04/2004 and 09/13/2007). * 'f

This letter is signed with an advanced electronic signature (FIEL), based on articles 7 BIS 2 of the Industrial Property Law; 3 of its Regulations, and 1 section III, 2 section V, 26 BIS and 26 TER of the Agreement establishing the guidelines for the use of the Electronic Payment and Services Portal (PASE) of the Mexican Institute of Industrial Property, in the procedures indicated.

B carry over, counted to rights

13765/1999, 01/26/2004, 06/16/2005, offYjRWO a), 4th and 12th sections I and III of _LW7 / 2004, 07/28/2004 and 09/07/2007);

THE DIVISIONAL DIRECTOR OF PATENTS

NAHANNY CANAL REYES

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Original string:

NAHANNY MARISOL CANAL REYES | 00001000000403252793 | Tax Administration Service | 1695 || MX / 2018/35996 | MX / a / 2015/010349 | Patent title PCT | 1220 | RRGO | Page (s) 1 | b4EwYp¡ + nlOj3FWmTdK4J99 =

Digital stamp:

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Arenal No. 550 Floor 1. Pueblo Santa María Tepepan, Xochimilco, 16020, Mexico City.

(55) 53340700 www.gob.mx/impi

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MX / 2018/35996

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SYSTEM AND METHOD FOR DETERMINING A SIGN ^TO kk ^ kk 'I ;,. ·; -, ·₇ , γ

LIFE OF A SUBJECT

Field of the Invention

The present invention relates to a system and method for determining a vital sign of a subject and to a sensor for use in this system and this method. The present invention is particularly concerned with patient monitoring systems and methods, for example used in intensive care units in hospitals.

Background of the Invention

A person's vital signs, for example heart rate (HR), respiratory rate (RR), or oxygen saturation (i.e. SpO2), serve as indicators of the current status of a object (i.e. a person or an animal) and as powerful predictors of serious medical events. For this reason, vital signs are monitored in hospital and outpatient treatment units, at home, or in additional health, recreation and fitness units. In this way, various sensors can be used to measure a vital sign information signal from which a corresponding vital sign can be obtained.

One way to measure vital signs is plethysmography. Plethysmography typically refers to the

Ref. 256953

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..... measurement of changes in volume of an organ or urík ^ jS &amp; rte * body and in particular the detection of changes in VülUHien due to a cardiovascular impulse wave that travels through a subject's body with each heartbeat . Photo-plethysmography (PPG) is an optical measurement technique that evaluates a variant change in the time of reflectance or light transmission of an area or volume of interest. PPG is based on the principle that blood absorbs more light than surrounding tissue, so that variations in blood volume with each heart beat consequently affect transmission or reflectance. In addition to information about heart rate, a PPG waveform may comprise additional integrated information that is attributable to respiration and additional physiological phenomena. By evaluating transmissivity and / or reflectivity at different wavelengths (typically red and infrared), oxygen saturation in the blood can be determined.

Conventional pulse oximeters to measure a subject's heart rate and oxygen saturation are attached to the subject's skin, such as the tip of a finger, the earlobe, or the forehead. Therefore, they are referred to as contact PPG devices. A typical pulse oximeter comprises a red LED and an infrared LED as light sources and a photodiode to detect

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MEXICAN INSTITUTE

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INDUSTRIAL light that has been transmitted through a patient's tissue. Transmissivity in the red and infrared spectral range is measured by time multiplexing. Transmissivity over time provides the red and infrared PPG waveforms.

It is well known that the frequent occurrence of false medical alarms in the hospital, for example, alarms generated by patient monitoring devices in the intensive care unit (ICU), presents a serious and unresolved problem due to that it leads to desensitization of health professionals to alarms. Additionally, it is known that the high sensitivity of modern patient monitoring systems leads to alarm noise levels around 80 dB at today's average IUCs, which is comparable to traffic noise on a main street. However, up to 90% of recorded alarms are medically irrelevant. Technical alarms, which make up approximately 22% of all alarms, are frequently due to poor sensor signals due to patient movement. This is especially the case for SpO2 related alarms, which constitute up to 79% of technical alarms.

Therefore, it seems beneficial to obtain relevant information on the movement of the sensors and use this

<img file="MX355772B_D0006.tif" />

information to reduce the probability of alarms'!

This is particularly important in 'Trtmjun-crón-- ™ - ~ eon-- ~ -, patient approaches with fewer cables, where the patient can move freely from here to there in the hospital.

WO 2008/055949 Al discloses an apparatus for motor training and exercise of a human body comprising means for acquiring biophysiological data and movement parameters related to a voluntary action of a human, means for processing, storing and summarizing the acquired data and parameters and means to return at least two feedbacks of information related to the acquired data and parameters, or acquired and processed, adapted to facilitate the correction of the voluntary action of a human being performed, the information return means is designed to use at least one sensory channel.

US 2007/0132597 Al discloses methods, systems, and software products to monitor patient support outcomes and to initiate a response to prevent or mitigate harm. One or more cameras provide a stream of video data from a patient resting on a bed, chair, wheelchair, gurney, recliner, or other support. A computer system analyzes the video data stream and determines the location and / or movements of it, relative to a fixed reference (for example, the support). A profile containing personalized patient support outcome data is used to accurately predict the outcome of the support. Intervention to prevent or mitigate harm in the event a support outcome is detected may include an alarm, audio / visual communication, and / or direct physical intervention. Patient profiles can be updated in response to observed behavior to better predict the outcome of support.

Brief Description of the Invention

An object of the present invention is to provide an improved system and method for determining a vital sign of a subject whereby the probability of false alarms is reliably and considerably reduced. Another object of the present invention is to provide a sensor for use in this system and this method.

In a first aspect of the present invention, a system for determining a vital sign of a subject is presented, comprising a vital sign processor designed to process the vital sign information signal measured by a sensor attached or incorporated to a subject to obtain a ri ·· sign. 7

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vital of the subject, an image analysis unit nés ~ 'pára' detect “SΪ movement of a marker attached to the sensor from image data obtained by a graphical representation unit of at least one graphical representation region containing the sensor, and an alarm unit for generating and sending an alarm signal based on the measured vital sign information signal and / or the obtained vital sign and the detected movement of the marker.

In a further aspect of the present invention, a method for determining a subject's vital sign is presented which comprises processing a measured vital sign information signal from the subject, detecting the movement of a marker attached to the sensor from image data obtained from at least one graphical representation region containing the sensor, and generating and sending an alarm signal based on the measured vital sign information signal and / or the obtained vital sign and on the detected movement of the marker.

In yet another aspect of the present invention, a computer program is provided which comprises program code means for causing a computer to go,. / · '; ·; s ··. Do the steps of the proposed method when the computer program is carried out on a computer, —Also, — £ presents a non-transient computer-readable recording medium that stores this product of a computer program, which, when executed by a processor, causes the steps of the method disclosed in this document to be performed.

Preferred embodiments of the invention are defined in the dependent claims. It should be understood that the claimed method, computer program and medium have similar and / or identical preferred modalities as the claimed system and as defined in the dependent claims.

The use of video cameras for patient monitoring, particularly in the hospital, has become increasingly widespread. Hereby, image data (eg continuous video data) can be used to directly measure (discretely and non-contact) vital sign information using the principle of distant photoplethysmography (distant PPG, as described for example in Wim Verkruysse, Lars 0. Svaasand, and J. Stuart Nelson, Remóte plethysmographic imaging using ambient light, Optics Express, Volume 16, No. 26, December 2008) or for more general information on non-vital signs about the patient's condition such as through the

J Τ. ν τυ j video-actigraphy. In the latter case, a video analysis may reveal some global information on the patient's movements, but it may be insufficient information to make assessments of the reliability of the signals from particular sensors coming from the patient.

Therefore, the present invention proposes the integration of a marker with the (medical) sensor. Through the use of image data - often a graphical display unit already available (eg from a distant PPG system or a video-actigraphy system) of a certain graphical display region, in which the sensor is located they are obtained so that sensor movements can be reliably and accurately determined from the detected movement of the marker identified in the image data. In this way, a real-time analysis of marker motion trajectories can be made from image data that provides direct evidence about the motion and reliability of sensor signals. This evidence can then be used by the alarm unit to reduce the probability of false alarms.

In accordance with one embodiment, the alarm unit is configured to generate and send an alarm signal if the measured vital sign information signal and / or the obtained vital sign meet a first condition and if movement

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ΙΝ ^ ΤΓ * ·: τ &lt;· · Κ '· Λ Τ — ϊ inst: ·; utc '·:?; year detected of the marker complies with a segtift ^ / j / ^ ndCjj These conditions are generally predetermined and are dependent on one or more of the following factors including the sensor class, the marker class, the position of attachment of the sensor to the body of the subject, the desired accuracy of suspending false alarms, etc. For example, a first different condition is generally used for an SpO2 sensor than for a heart rate sensor. The conditions may also be available for modification by the user.

In accordance with another embodiment, the alarm unit is configured to generate and send an alarm signal if the measured vital sign information signal and / or the obtained vital sign meet a first condition, where the first condition is adapted to based on the detected movement of the marker. In this way, for example, if the marker is moving stronger, the first condition is adapted in such a way that false alarms are suppressed or that only an alarm is generated and sent and a higher probability is given that it actually exists. an alarm.

According to another embodiment, the alarm unit is configured to generate an alarm signal if the measured vital sign and / or vital sign information signal obtained meets a first condition, where the sending of the alarm signal is suppressed if the detected movement of the p / '”l' * 'marker meets a second condition. ^k Of this m ^ ne ^ á ^.

Another way to control the generation and sending of alarms is provided in accordance with this modality.

The alarm unit is preferably configured to use as a first condition a lower and / or higher threshold of the level of the measured vital sign information signal and / or the obtained vital sign. For example, the highest and / or lowest heart rate limit or a lower oxygen saturation limit can be used if a corresponding sensor is used.

Furthermore, the alarm unit is preferably configured to use as a second condition a movement threshold indicating the intensity, frequency and / or pattern of movement of the marker. In this way, for example depending on the class and location of the sensor, an appropriate condition can be selected.

Advantageously, the alarm unit comprises a communication interface to communicate the alarm signal to an alarm indication unit to indicate an alarm. While the alarm unit can directly send the alarm, for example as a visual and / or audible signal, it is preferred that the alarm be indicated on a separate indication unit. This indicating unit may be in the form of a screen, a loudspeaker, a mobile phone, etc. on which the alarm is issued, for example as a

<img file="MX355772B_D0008.tif" />

flashing signal, a shrill alarm sound or -4jn.a. phone call. There are a number of other - commodities - corduroy, this indicating unit, which can be arranged in a distant location, for example in a centrally supervised room or an infirmary at a hospital station.

There are several modalities for markers that can be used in accordance with the present invention. In a first embodiment, the marker is a passive marker that comprises a graphic pattern. The graphic pattern is preferably designed such that the movement of the marker can be best detected from image data. Furthermore, in one embodiment the graphic pattern is preferably machine-readable (such as a QR code, a barcode, or simply graphic signs or letters), particularly if the graphic pattern is configured to contain information about the subject and / or the sensor and where the image analysis unit is configured to determine the information from the graphic pattern, as proposed in an additional modality. The marker can then be tracked with the graphing unit. This machine-readable marker can also be adapted to existing sensors. For example, the marker can be implemented as a label which can be placed over an existing SpO2 contact finger probe

<img file="MX355772B_D0009.tif" />

or a cuff to take blood pressure, etc.

In a second mode, the., Marker- &amp; s ~ —λλο active marker that is configured to emit light. For example, an active light source (eg an LED) may be used or a self-illuminated material (eg a fluorescent or phosphorescent material) may be used in or on the marker. The active marker can be conceived as a luminous beacon, which emits light into the environment. The light intensity can be variable with time, that is, a coded light can be emitted. With the coded light, information about the particular sensor and / or the patient can be diffused, for example, each sensor can emit its own unique identification light code as proposed in a preferred embodiment whereby the active marker is configured to emit light containing information about the subject and / or the sensor and where the image analysis unit is configured to determine the information from the emitted light. The light emitted can be visible or invisible (eg infrared light) to the human eye. Through the identification of emitted light a sensor can then be uniquely identified and tracked by the graphics display unit.

In a third embodiment, the marker can comprise both an active and passive marker element as described above. ,,

Preferably, the image analysis unit is configured to detect the location of the marker and one or more additional markers attached to one or more additional sensors and / or the subject's body from the image data. In addition, the alarm unit is configured to generate and send an alarm signal if a sensor is detected to be not attached or is attached incorrectly or to an incorrect portion of the subject's body and / or attached to an incorrect subject. In this way, by using various markers, various sensors and subjects can be easily distinguished, and certain situations of sensor misuse or malfunction can also be detected.

Furthermore, in one mode the alarm unit is

<td colspan="4">set up to generate and send a signal</td><td>of</td><td>alarm yes</td><td>the</td>

<td>marker</td><td>not</td><td>can</td><td>be detected in</td><td>a</td><td>region</td><td>of</td>

<td colspan="2">representation</td><td>graph</td><td>This makes it possible</td><td>the</td><td>detection</td><td>of</td>

situations when a sensor is covered, for example by a sheet, or is detached from the patient, or even a situation when a patient is no longer in any way in the graphing region, for example, fell out of bed.

It should be noted that the term vital sign used in the context of the present invention refers to a physiological parameter of a subject. In particular, the

<img file="MX355772B_D0010.tif" />

vital sign term includes variability of the frequency the cardiac heart rate, waves of

<img file="MX355772B_D0011.tif" />

Traube

Hering Mayer, respiratory rate (RR), body temperature, blood pressure, concentration of a substance in the blood and / or tissue, such as an oxygen saturation or glucose level. A sensor as used in this document is thus a sensor that can measure one or more vital sign information signals from which this vital sign can be obtained, that is, it either directly represents a vital sign or is you can process or analyze to get the vital sign.

Furthermore, it should be noted that the sensor (s) for the vital sign information signal (s) and the graphing unit for obtaining image data from at least one graphing region that The sensor contains are generally non-essential parts of the proposed system. In preferred embodiments, however, the sensor (s) and / or the graphics display unit are part of the proposed system.

In a preferred embodiment, the sensor is a plethysmographic sensor comprising at least one light source for emitting light onto the skin covered by the sensor, wherein the sensor is designed in such a way that light from at least one source of light is emitted in a direction away from the skin so that the light source functions as a

<img file="MX355772B_D0012.tif" />

institute: /..- 0 ίσε LA IVÜTODaO \ active marker. In this way, it is proposed to reut? O> uí¡ií®ar more light sources (for example LEDs, for-, .example — u »—LEBinvisible infrared), which are already integrated inside, along with their wiring existing to facilitate the functionality of luminous headlight.

Preferably, in an embodiment at least part of the sensor housing carrying one or more of the light sources is made of a translucent material. This ensures that the sensor can be observed from many directions (preferably from all directions), ie the detection of the light source (as a marker) is not (very much) dependent on the actual position of the subject's hand. As an added effect, the large surface area of ​​the sensor works as a light emitter and achieves an emission pattern closer to 360 degrees.

Furthermore, the electric current or voltage to activate the light source is configured such that it modulates at a rate that is higher than the subject's heart rate. In this way, high-frequency coded light emission is achieved without additional hardware (physical components) cost to the sensor or wiring. Hereby, light modulation does not interfere with the SpO2 measurement process since light modulation is in a high frequency band compared to heart rate (say above 30 Hz). The measurement of

SpO2 and the encoded light emission could also be performed sequentially in a form of multiple ± ~ -pcrr "" rapid time division.

In yet another aspect of the present invention, a plethysmographic sensor is presented which comprises at least one light source for emitting light onto the skin of a subject covered by the sensor and a light detector for receiving reflected light from and / or transmitted through the subject's skin, where the sensor is designed in such a way that light from at least one light source is emitted in a direction away from the skin.

Brief Description of the Figures

These and other aspects of the invention will be apparent from and will be clarified with reference to the embodiment (s) described hereafter. In the following figures

<td></td><td>The</td><td>Figure</td><td> 1</td><td>shows</td><td>a first</td><td>modality</td><td>of</td><td>a</td>

<td>system</td><td>for</td><td colspan="2">decide</td><td>a sign</td><td>vital of a</td><td>subject,</td><td></td><td></td>

<td></td><td>The</td><td>Figure</td><td> 2</td><td>shows</td><td>A second</td><td>modality</td><td>of</td><td>a</td>

<td>system</td><td>for</td><td colspan="2">decide</td><td>a sign</td><td>vital of a</td><td>subject,</td><td></td><td></td>

<td></td><td>The</td><td>Figure</td><td> 3</td><td>shows</td><td>a third</td><td>modality</td><td>of</td><td>a</td>

<td>system</td><td>for</td><td colspan="2">decide</td><td>a sign</td><td>vital of a</td><td>subject,</td><td></td><td></td>

<td></td><td>The</td><td>Figure</td><td> 4</td><td>shows</td><td>a diagram</td><td>flow</td><td>of</td><td>a</td>

<td>method]</td><td>for &lt;</td><td colspan="2">decide ·</td><td>a sign</td><td>vital of a</td><td>subject, and</td><td></td><td></td>

<td></td><td>The</td><td>Figure</td><td> 5</td><td>shows</td><td colspan="2">another modality of a</td><td colspan="2">sensor</td>

for use in a system of invention.

-AJ · agreement with I'á``presente ''

Detailed description of the invention

Figure 1 schematically shows a first embodiment of a system 1 for determining a vital sign of a subject 100. Subject 100, in this example a patient, lies on a bed 101, where the head of subject 100 is located on a pillow 102 and subject 100 is covered with a sheet 103. A sensor 10 is attached to subject 100 to measure a vital sign information signal from the subject. Herein, sensor 10 is a blood pressure cuff disposed over the top of the subject's ear to measure subject 100 blood pressure.

A marker 20 is attached to sensor 10, for example printed on the outer surface of the cuff to take blood pressure or attached therein in the form of a label. In this embodiment, marker 20 is a passive marker comprising a graphic pattern 21, in this document a commonly called QR code. The QR code can have different structural elements that allow a machine-readable determination of the orientation and / or location of the graphic pattern 21. Marker 20 can be visible or invisible to the human eye, for example it can be printed by using a certain ink (for example infrared or fluorescent) so that only ^ 'j ^^ a' - ^ laei »» · detected through the use of a display unit ...... ,,, special graphic and / or after lighting with a certain light source (for example with infrared light).

The system 1 comprises a vital sign processor 30 to process the vital sign information signal measured by the sensor 10 to obtain a vital sign from the subject, i.e. to obtain the blood pressure (in particular the systolic pressure and the diastolic pressure) for which it may be necessary for the signal sent by the sensor 10 to be processed or may already contain this information, that is, the vital sign information signal may directly represent the vital sign or may require some processing to obtain the vital sign.

A graphics display unit 40 is provided to obtain image data from at least one graphic display region 41 containing the sensor 20. The graphic display unit 40 is preferably a camera, such as a video camera (for example a CCD camera or an infrared camera), which has a field of view 42 that is directed to the desired graphing region in which the sensor 20 is located. Preferably, the field of view 42 is configured to monitor a larger area, for example an area containing the entire subject 100. In certain practical situations, such as in a hospital ICU, this graphical display unit 40 is already available. eg for monitoring subject 100 or discretely determining a vital sign using the principle of distant photo-plethysmography.

If a special marker is used which requires a certain illumination to be detectable by a graphics display unit 40, for example requires illumination by means of infrared light, a corresponding illumination unit (for example an infrared LED) can also be provided ( which is not shown in Figure 1).

The system 1 further comprises an image analysis unit 50 to detect the movement of a marker 2 0 attached to the sensor 10 from the image data obtained by the graphic display unit 40. The image analysis unit 50 may be an image processor, for example using an object detection or image recognition algorithm, which is adapted to detect the location and / or orientation of the marker 2 0 in the image data and that it is capable of detecting movement of marker 20 with high accuracy.

For example, a movement path, that is to say movement through time, of marker 20 can be detected which reflects the movement of sensor 10 over time.

Finally, system 1 comprises a unit of ~ INS · il · · .; :. · Ύ. ·. '.'. r alarm 6 0 to generate and send an a-la signal ^ ma ·:,; ^ οη_ base,. / in the measured vital sign information signal and / or the obtained vital sign and in motion detected from marker 20.

Alarm unit 60 may be a processor configured to process the signals to determine whether or not an alarm should be generated and sent.

Generally, an alarm is generated if the vital sign information signal and / or vital sign meet a first predetermined condition, which may be predetermined by the user or a supervisory person (eg, a nurse or doctor). In the example of blood pressure as a vital sign, the first condition may be a lower and / or upper limit value for systolic and / or diastolic blood pressure, where the limit values ​​generally depend on the patient and their health condition. For example, if a predetermined upper limit value for systolic blood pressure is exceeded, an alarm should be generated and sent to inform the supervising person (for example via a signal on an alarm indicator, such as a display on a central supervisory room) that the person needs particular attention, for example the administration of a certain medicine or medical treatment.

In practical situations, the vital sign information signal measured by sensor 10 can be falsified or bad for various reasons. A primary reason^Tn ^ |) al'uSsqñ 1 © 3_Ζ· Movements of subject 100 which generally cannot be prevented. These movements may not be very crucial for blood pressure measurements, but they can be very crucial for SpO2 measurements where they frequently lead to false alarms in practice.

In accordance with the present invention, the number of false alarms is greatly reduced with high reliability, whereby false alarms are not suppressed. This is achieved by additionally taking into account the detected movement of marker 2 0 and, thus, sensor 10 by alarm unit 60. In general, if the sensor is moved a lot during the measurement of a vital sign information signal which would result in an alarm, the alarm is either considered a false alarm or additional measurements are taken to obtain a measurement without (or with less) sensor movement, Or the first condition is tailored to make sure that there is actually a condition for generating and sending a real alarm and it is not a situation where the movement falsified the measurement in such a way that it looks like a real alarm situation.

In particular, in one mode the alarm unit 6 0 generates and sends an alarm signal if the measured vital sign information signal and / or the obtained vital sign meets a first condition and if the detected movement of the marker 2 0 meets with a

<img file="MX355772B_D0013.tif" />

Generally, the first condition may be a lower and / or higher threshold of the measured vital sign information signal level and / or the obtained vital sign (in the example above a higher systolic blood pressure level). The second condition may be a threshold of movement indicating the intensity, frequency, and / or pattern of marker movement. In this way, if the marker has been moved less than allowed by the second condition (i.e. with only low intensity or even nothing at all) an alarm is generated and sent if the first condition is met, otherwise it will not be generates and / or sends an alarm even if the first condition is met.

In another embodiment, alarm unit 60 generates and sends an alarm signal if the measured vital sign information signal and / or the obtained vital sign meets a first condition, wherein the first condition is adapted based on movement detected from the marker. For example, if marker movement is detected, in the above example the upper systolic blood pressure level can be increased which must be accomplished to evaluate the blood pressure measurement as critical justifying the generation and sending of an alarm.

In yet another mode, the alarm unit generates and sends an alarm signal if the information signal

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a first condition, where the sending-of-the_alarm signal is suppressed if the detected movement of the marker meets a second condition. For example, if the marker has been moved more than allowed by the second condition, an alarm is not sent even if the first condition is met.

The sending of the alarm by the alarm unit 60 should be understood in such a way that at least one signal is sent indicating that an alarm has been generated and should be signaled in an appropriate manner. In this way, the sending of the alarm unit signal 6 0 is at least one kind of control signal that is regulated by another (possibly distant) entity 70, for example a screen, speaker, pager or mobile phone) to indicate an alarm, for example to display a flashing signal assigned to an icon representing a particular room or patient. For this purpose, the alarm unit 60 optionally comprises a communication interface 61 to communicate the alarm signal (for example via a computer network connection (wired or wireless), a telephone network, a mobile telephone network, etc.) to an alarm indication unit 7 0 (the other entity) to indicate the alarm.

Figure 2 schematically shows a second ί -7-7. .- 7 j / 'mode of a system 1' to determine a subject 100. In this mode, a pulse oximeter in the form of a finger clip is used as sensor 10 ', which is arranged on a patient's finger 104 to continuously measure oxygen saturation (SpO2) as a vital sign. These pulse oximeters are generally known in the field and should not be described in more detail in this document.

An active marker 20 'is arranged in or on sensor 10', herein in the form of a light source, for example an LED that emits visible or infrared light. Within the image data, the graphics display unit 40 can detect the active marker 20 'and can detect movements of the active marker 20' (and thus the sensor 10 ') over time. The other elements of the system basically correspond to the corresponding elements of the system 1 shown in Figure 1.

<td>The</td><td>marker</td><td> 20'</td><td colspan="2">you can conceive</td><td>as a</td><td>lighthouse</td>

<td>bright, the</td><td>which</td><td>emits</td><td>light inside</td><td>of the</td><td>environment.</td><td>The</td>

<td>intensity of</td><td>the light</td><td>can</td><td>be variable</td><td>with</td><td>time</td><td>, is</td>

that is, it can emit coded light. With the coded light, information about the particular sensor 20 'and / or the subject 100 can be diffused. In the case of using multiple sensors, each provided with its individual marker, each marker

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Instít; » ; . ··, // 3 / f> jr {? FX,_c. 'preferably emits its own unique identification code. Through the identif-i-eaeióa - of ··, light.

emitted, a sensor can then be uniquely identified and tracked with the graphics display unit 40, for example a video camera system. Real-time analysis of light beacon motion paths from image data provides direct evidence of sensor signal motion and reliability. This evidence can then be used in the alarm unit to reduce the probability of false alarms as explained above.

Furthermore, in this mode the alarm unit 60 comprises an alarm indication unit 62, for example a screen and / or a loudspeaker, to directly send an alarm, for example in the form of an audiovisual signal.

Conventional plethysmographic sensors have an integrated light source. For example, SpO2 contact sensors (such as a finger clip sensor or an ear clip sensor) have a red LED and an infrared LED which emit light through the attached body part and a photodetector for receive reflected light from and / or transmitted through the tissue. The housing of these sensors is generally made of a non-translucent material to optically protect the photodetector from other (interfering) light sources that could be present in the environment.

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In an additional form of üñ áé'néor ITT '¹'shown in Figure 5 which is used in a system environment according to the present invention, this sensor is used but with a sensor housing designed in such a way that the light from one of the light sources (preferably the source of invisible IR light ) is also emitted in the environment, that is, in a direction away from the skin. The cross section of one embodiment of this sensor 10 '' depicted in Figure 5 (designed as a finger clip sensor or SpO2 sensor) shows an optically isolated photodetector 11, an LED light source 12, a translucent outer part 13 of the housing and an opaque inner part 14 (such as an optical protective cover around part of the photodetector 11) of the housing. In the intermediate part between the photodetector 11 and the LED light source 12, the tissue 106 (ie the finger) is arranged. No wiring is shown as it is equivalent to that of a conventional SpO2 sensor.

In case the LED light source 12 itself allowed too much stray light to pass from the environment into the fabric 106 then two optically separate LEDs (which are not shown) can be used in another mode (but electrically connected in parallel, i.e. without additional wiring). An LED light source

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ílSlJLj f ¿ir, ¡. it then illuminates tissue 106 (downward in Figure 5) and the other LED light source then illuminates (upward in Figure 5) the translucent portion 13 of the sensor housing.

Thus, preferably than using an additional light source that functions as marker 20 'as shown in Figure 2, one of the already available light sources is used as an active marker that allows detection of movement of sensor 10. '' as explained above.

An embodiment of a system for determining a vital sign of a subject comprising this sensor 10 '' can be configured in this way to comprise a plethysmographic sensor comprising at least one light source that emits light on a subject's skin covered by the sensor and a light detector that receives reflected light from and / or transmitted through the subject's skin, wherein the sensor is designed in such a way that light from at least one light source is emitted in a direction away from the skin, a vital sign processor that processes the vital sign information signal measured by the sensor, a image analysis unit that detects the movement of the sensor from the image data obtained by a graphical representation unit of

<img file="MX355772B_D0016.tif" />

minus a graphical display region containing the sensor, and an alarm unit that generates and outputs an alarm signal based on the measured vital sign information signal and / or the obtained vital sign and the detected movement of the sensor.

Additionally, in yet another improvement the electric current or voltage supplied to the light source 20 '(in Figure 2) or 12 (in Figure 5) is modulated with a high-frequency information signal for the generation of light codes. This high frequency modulation has no effect on the actual SpO2 measurement process if the high frequency is well above the heart rate.

In this way, without any additional wiring, hardware or circuitry in the sensor, it can be easily transformed into a light headlamp which emits a coded light. This can then be used to suppress false alarms as described above. Furthermore, these sensor modalities ensure that the light source acting as the light beacon is visible (as much as possible) from any direction and under any position in which the patient could hold his hand.

Preferably, in this embodiment the light source emits the light (preferably coded) in a total pattern (360

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<img file="MX355772B_D0018.tif" />

degrees).

Figure 3 schematically shows a third embodiment of a system 1 '' for determining a vital sign of a subject 100. In this embodiment, system 1 '' comprises, in addition to the elements of system 1 shown in Figure

1, the additional sensors 10a, 10b which are ECG electrodes attached to the chest 105 of subject 100 to measure an ECG signal. The electrode signals are provided to an additional vital sign processor 30a (or, alternatively, the vital sign processor 30) where the electrode signals are evaluated to obtain the ECG signal as an additional vital sign which is also provided to alarm unit 60.

Each of the additional sensors 10a, 10b is provided with a respective marker 20a, 20b, which can be active or passive markers as described above. Markers 21a, 21b are also monitored by the graphics display unit 40 to detect their movement and, thus, the movement of sensors 10a, 10b. In this way, for each individual sensor 10, 10a, 10b, the signal measured by the respective sensor can be evaluated as being reliable. Furthermore, by jointly analyzing the detected locations of the various sensors belonging to a particular subject 100, it is possible to recognize the situations when a sensor

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Particular detaches (falls off) from the subject, a sensor is not attached to the sensor (for example if the sensor is not in the field of view of the graphical display unit 40, or is very far from the other sensors of that subject) , or the sensor was mistakenly attached to a different / incorrect subject. If this case is detected, an appropriate alarm can be generated and sent.

It should be noted that, particularly in an ICU unit, the sensors are generally exposed, that is, they are not covered by sheets or the like, but they are in the field of view of the graphic display unit which is mounted for example on the ceiling. In case the marker is covered by a sheet and cannot be detected in the image data, location information cannot be retrieved. This information (ie, the sensor is invisible) can still be transmitted to alarm unit 60, which can then operate in the conventional mode. However, during all other times, that is, when the sensor and its marker are visible, information about sensor movement is available and can be used to reduce false alarms.

Figure 4 shows a flow chart of a method for determining a subject's vital sign. In a first step S10 a measured vital sign information signal from the subject is processed to obtain a vital sign from the

ΙΙ «Ί: τ / ¿// and.-Λ subject. In a second step S12, the movement of a marker attached to the sensor is detected from the image data obtained from at least one graphical region containing the sensor. Finally, in a third step S14, an alarm signal is generated and sent based on the measured vital sign information signal and / or the obtained vital sign and on the detected movement of the marker.

These steps of the method can be carried out by an individual processor or computer (for example, running a corresponding algorithm) or by several separate processors or computers, or by specialized hardware that is designed for this purpose.

An exemplary scenario will be described below. A sleeping ICU patient lying on a bed with his hands / arms on top of the sheet should be considered. The patient has a finger clip sensor equipped with a marker attached to one of their fingers to facilitate continuous heart rate (HR) monitoring. When this sensor moves, for example due to patient movements, the HR measurement (referred to as the HR signal hereafter) is highly unreliable due to signal artifacts. During these movements, the HR deducted (falsely) may be outside the acceptable limits.

The patient periodically adjusts his position in the

INSTITUI! ,. ..._m·· ⁰¹/ A / -A ^ SiT '»' ** bed and move your hand during the process. This' ^ may take many seconds. The HR signal continues cbñLfcihitíiider · artifacts during movements. The inferred HR is continuously high (say 200 BPM) due to false peak detections in the HR signal. This is outside the acceptable HR range, and an alarm must be generated. In accordance with the present invention, however, rapid motion of the sensor is simultaneously detected in a video data stream that is monitored by the patient. The alarm unit (for example, a processor that runs a computer program to cause the processor to carry out the steps of the proposed method), however, decides not to generate the alarm because both the HR is out of bounds and that the sensor is moving, i.e. a false alarm is prevented.

Once the patient's movement is over the patient's condition deteriorates and the HR actually increases beyond safe levels. In this situation, no motion of the sensor is detected in the video data stream. The HR calculation is determined to be reliable. Then, because the HR is very high and the sensor is not moving, an alarm is correctly generated and sent.

A similar scenario applies to non-invasive blood pressure measurements (NIBP) with a cuff equipped with a marker, where the &lt;= a.Tc ..- aJ: · ν, '·. V ') ¿r3' Sa ¡I ,: JO Vrffe'IE'íTj c; or*. ¡.-. OoeoAo C '*** v¿-2¿ INDUSTRIAL measurement is only reliable when the patient does not move. An ICU patient in a bed should be considered again. A NIBP measurement is initiated by the system. If the patient moves during the process, the sensor / marker will move. If the intensity of movement is beyond a certain threshold, unreliable NIBP measurement results will be discarded and an alarm will not occur. Instead, another measurement can be started soon after.

While the invention has been illustrated and described in detail in the figures and description above, this illustration and description are to be considered as illustrative or exemplary and are not to be considered restrictive; the invention is not limited to the disclosed modalities. Other variations to the disclosed modalities can be understood and made by those skilled in the field in the practice of the claimed invention, from a study of the figures, the description and the appended claims.

In the claims, the word comprises does not exclude other elements or steps, and the indefinite article one or one does not exclude a plurality. An individual element or another unit can fulfill the functions of the various articles cited in the claims. The mere fact that certain measures are set out in mutually different dependent claims does not indicate

<img file="MX355772B_D0019.tif" />

that a combination of these measures cannot be used to profit.

A computer program can be stored / distributed on a suitable non-transient medium, 5 such as an optical storage medium or a solid state medium supplied together with or as part of other hardware, but it can also be distributed in other ways, such as such as via the Internet or other wired or wireless telecommunication systems.

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

It is noted that in relation to this date, the best method known by the applicant to put the aforementioned invention into practice is the one that is clear from the present description of the invention.

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