Patent Application
20100210926
This application claims priority from German Patent Application No. 102009008604.8, which was filed on Feb. 12, 2009 and is incorporated herein in its entirety by reference.
The present application relates to a measuring apparatus and to a method of monitoring one or several vital parameters of a person, e.g. detecting an arterial plethysmogram, the heart rate, the heart rate variability, the oxygen content of the arterial blood, and the pulse wave transmission time.
Known methods of detecting vital parameters comprise optical plethysmography and pulse oximetry, for example. Optical plethysmography and pulse oximetry are based on similar measuring methods. They consist in an active sensor apparatus which contains a light source and a photo receiver and is designed such that light passes the tissue layers, and that the remaining light intensity is measured by the photo receiver. When the light passes the tissue layer, it undergoes attenuation which is dependent, among other things, on the wavelength of the light, on the type and concentration of the substances within the irradiated tissue, and on the volume changes in the arterial bloodstream. The photo receiver converts the impinging light to a photocurrent, the amplitude of which is modulated by the volume changes in the arterial vessels, which are caused by myocardial contractions.
Optical pulse oximeters and optical plethysmographs are typically attached to the finger or earlobe of the patient, because in said places, the upper skin layers are densely interspersed with arterial blood vessels, and the attenuating influence of bone or fat tissue is at a minimum. The plethysmographs employed are both those based on the transmission principle and those based on the remission principle. For the remission method, the finger is not entirely irradiated as for the transmission method, but that light portion which is emitted, or, in other words, reflected or remitted, by the tissue following the irradiation with light, is measured. Restriction of the patient's freedom of movement is common to all of the optical plethysmographs and pulse oximeters for being used on a finger, for example attached to the fingertip by means of a finger clip. In addition, such sensors exhibit a very sensitive reaction to low blood circulation and/or vasoconstriction of the peripheral arterioles, which considerably complicates taking and evaluating the plethysmogram and vital parameters that may be derived, such as heart rate, heart rate variability, oxygen content of the arterial blood, and pulse wave transmission time.
In other methods, the measurement is performed in that the source of light is inserted into a nostril of a patient, and a light sensor is inserted into the other nostril, so as to perform the measurement on the basis of the bloodstream within the nasal septum.
According to an embodiment, an apparatus for detecting at least one vital parameter of a person may have: an optoelectronic sensor arrangement for detecting the at least one vital parameter by means of light transmission, the optoelectronic sensor arrangement including a light source and a light-sensitive element, the light source being arranged in a first side part of a support frame of a pair of spectacles, and the light-sensitive element being arranged in a second side part of the support frame which is opposite the first side part.
According to another embodiment, an apparatus for detecting at least one vital parameter of a person may have: an optoelectronic sensor arrangement for detecting the at least one vital parameter by means of light remission, the optoelectronic sensor arrangement including a light source and a light-sensitive element, the light source and the light-sensitive element being arranged in the same side part of the support frame of the pair of spectacles.
According to another embodiment, a method of detecting at least one vital parameter of a person by means of an optoelectronic sensor arrangement, wherein the optoelectronic sensor arrangement includes a first number of light sources and a second number of light-sensitive elements, a light source of the first number of light sources being allocated to a light-sensitive element of the second number of light-sensitive elements in each case and forming with same a selectable measurement allocation of a third number of selectable measurement allocations, may have the steps of: performing at least one optoelectronic measurement for the selectable measurement allocations so as to generate at least one measurement result in each case; determining an amplitude-dependent measurement quality for each of the selectable measurement allocations on the basis of the at least one respective measurement result; selecting that measurement allocation of the third number of measurement allocations which has the highest amplitude-dependent measurement quality; and performing at least one optoelectronic measurement by means of the selected measurement allocation so as to detect the at least one vital parameter on the basis thereof
According to another embodiment, a vital parameter detection system may have: an apparatus for detecting at least one vital parameter of a person, which apparatus may have: an optoelectronic sensor arrangement for detecting the at least one vital parameter by means of light transmission, the optoelectronic sensor arrangement including a light source and a light-sensitive element, the light source being arranged in a first side part of a support frame of a pair of spectacles, and the light-sensitive element being arranged in a second side part of the support frame which is opposite the first side part; and a controller configured to perform a method of detecting at least one vital parameter of a person by means of an optoelectronic sensor arrangement, wherein the optoelectronic sensor arrangement includes a first number of light sources and a second number of light-sensitive elements, a light source of the first number of light sources being allocated to a light-sensitive element of the second number of light-sensitive elements in each case and forming with same a selectable measurement allocation of a third number of selectable measurement allocations, which method may have the steps of: performing at least one optoelectronic measurement for the selectable measurement allocations so as to generate at least one measurement result in each case; determining an amplitude-dependent measurement quality for each of the selectable measurement allocations on the basis of the at least one respective measurement result; selecting that measurement allocation of the third number of measurement allocations which has the highest amplitude-dependent measurement quality; and performing at least one optoelectronic measurement by means of the selected measurement allocation so as to detect the at least one vital parameter on the basis thereof.
According to another embodiment, a vital parameter detection system may have: an apparatus for detecting at least one vital parameter of a person, which apparatus may have: an optoelectronic sensor arrangement for detecting the at least one vital parameter by means of light remission, the optoelectronic sensor arrangement including a light source and a light-sensitive element, the light source and the light-sensitive element being arranged in the same side part of the support frame of the pair of spectacles; and a controller configured to perform a method of detecting at least one vital parameter of a person by means of an optoelectronic sensor arrangement, wherein the optoelectronic sensor arrangement includes a first number of light sources and a second number of light-sensitive elements, a light source of the first number of light sources being allocated to a light-sensitive element of the second number of light-sensitive elements in each case and forming with same a selectable measurement allocation of a third number of selectable measurement allocations, which method may have the steps of: performing at least one optoelectronic measurement for the selectable measurement allocations so as to generate at least one measurement result in each case; determining an amplitude-dependent measurement quality for each of the selectable measurement allocations on the basis of the at least one respective measurement result; selecting that measurement allocation of the third number of measurement allocations which has the highest amplitude-dependent measurement quality; and performing at least one optoelectronic measurement by means of the selected measurement allocation so as to detect the at least one vital parameter on the basis thereof.
An embodiment of the present application provides an apparatus for detecting at least one vital parameter of a person, comprising: an optoelectronic sensor arrangement for detecting the at least one vital parameter by means of light transmission or light remission, the optoelectronic sensor arrangement comprising a light source and a light-sensitive element, wherein for detecting the vital parameter by means of light transmission, the light source is arranged in a first side part of a support frame of a pair of spectacles, and the light-sensitive element is arranged in a second side part of a support frame which is opposite the first side part, so that when the glasses are placed on the person's nose, the light of the light source may irradiate the nose for detecting the vital parameter, and for detecting the vital parameter by means of light remission, the light source and the light-sensitive element are arranged in the same side part of the frame, so that when the glasses are placed on the person's nose, the light-sensitive element may receive a portion of the light generated by the light source, said portion being reflected by the nose.
Such an integration of the optoelectronic sensor arrangement into a pair of spectacles enables measuring the vital parameter on the basis of the blood flow of the dorsal nasal artery and/or the angular artery, and therefore is hardly affected by vasoconstriction.
Vasoconstriction appears, for example, in stressful situations, situations of low blood pressure or of hypothermia. The vessels of the legs and arms are constricted so as to achieve improved blood circulation, or a higher blood pressure, in the vital organs, e.g. the brain and the heart. The dorsal nasal artery and the angular artery are direct derivations, or branches, of the internal cervical artery and are therefore less affected by vasoconstriction than the usual points of measurements such as finger, toe or earlobe, for example. Therefore, embodiments enable reliable detection of the vital parameters even in the above-mentioned particular situations.
A further embodiment of the present invention of transmission measurement is characterized in that the support frame of the pair of spectacles is rigid, and the light source and the photosensor have a fixed mutual geometric arrangement defined by the support frame. In this manner, distortion of the measuring results which is due to relative motion of the light source with regard to the light-sensitive element is reduced.
In accordance with a further embodiment of detecting by means of light transmission, the photosensor is arranged, in the one side part of the support frame, such that a direction of a maximum light output of the first photosensor corresponds to the shortest path of the light from the first photosensor to the light element in the oppositely located second side part of the support frame. This enables reducing the energy requirement of the sensor arrangement while keeping the quality of measurement at the same level, or an increase in the quality of measurement while keeping the same energy supply at the same level.
In a further embodiment of the present invention, the optoelectronic sensor arrangement comprises several light sources and light-sensitive elements which are arranged, in a spatially distributed manner, in the side part(s) of the support frame, and are mutually allocated in pairs, and additionally a control means designed to select, from said several pairs of light sources and light-sensitive elements, that pair which provides a higher quality of measurement as compared to the other pairs. Thus, that measurement pair may be selected which is located closest to an artery in the state of the pair of spectacles being worn, and thus, the quality and reliability of the detection of the vital parameters may be improved.
Embodiments of the present invention will be detailed subsequently referring to the appended drawings, in which:
Identical reference numerals will be used in the present invention for objects and functional units having identical or similar functional properties.
Embodiments of the apparatus further comprise a control means electrically connected to the light source 1 and the light-sensitive element 1′ (not shown) and designed to activate the light source in order to measure a vital parameter, so that said light source generates light of a specific wavelength or wavelength range which radiates through the nose 190 (see arrow 180). Some of the light is absorbed by the tissue layers of the nose 190, so that the light-sensitive element 1′ receives only some of the light, namely the transmitted portion of the light. The degree of absorption or transmission depends on the nature of the tissue and the volume changes in the bloodstream.
As may be seen from
The vital parameters may be determined, for example, from the amplitude and the amplitude response of the electric signal, e.g. the curve of a photocurrent or a photovoltage, or from a Fourier transformation of said electric signal. Embodiments of the present invention comprise a control or drive circuit which controls the light source 1 with high light intensity, but very short pulses so as to keep the current consumption of the light source low, and comprise, on the receiver side, namely on the side of the light-sensitive element 1′, a peak detector so as to enable reliable digital sampling of the analog plethysmographic signal despite the short light pulses.
Further possibilities of optoelectronic measurement are based on performing a Fourier transformation of the signal measured, rather than on measuring the amplitude.
For detecting the oxygen content (oximetry), one embodiment of the apparatus for detecting comprises two light sources which detect light in light wave ranges which are different from each other. Due to the different coloring of the hemoglobin saturated with oxygen, the two irradiating lights undergo different degrees of absorption, which are measured by the light-sensitive element. An evaluation unit may then determine the oxygen saturation of the blood in the arteries, for example by means of comparing the measurement results with a reference table.
Examples of light sources are light emitting diodes (LEDs), and examples of the light emitting elements are so-called photodiodes. An embodiment that is to measure the oxygen content of the blood may comprise a red diode, which generates visible light in the 660 nanometer range, for example, and an infrared light emitting diode as a further light source which generates a light in the wavelength range of 940 nanometers, for example, which is not visible to humans.
In general terms, the light source is configured to generate light of a first wavelength or wavelength range, and the second light source is configured to generate light of a second wavelength or wavelength range, the first and second wavelengths or wavelength ranges being different from each other.
The support frame of the pair of spectacles may be configured in a flexible manner in that the distance between the first side part 110 and the second side part 110′ of the support frame changes slightly, for example increases, depending on the width of the nose, when the pair of spectacles is placed on a nose 190, or may be essentially rigid, and therefore the distance between the first side part 110 and the second side part 110′ and, thus, between the light source 1 and the light-sensitive element 1′ essentially does not change.
A rigid implementation of the support frame results in that the light source 1 and the light-sensitive element 1′ have a fixed mutual geometric arrangement defined by the support frame, and therefore results in the risk that the steady component 205 of the signal is changed by a change in the distance between the light source and the light-sensitive element, and that the measurement results are consequently distorted.
Embodiments of
Accordingly, light-sensitive elements whose degree of efficiency in converting the light received to electric energy is dependent on the direction, are also arranged such that the light generated by the light source 301 is received from this direction (see arrow bearing the reference numeral 380).
Corresponding transparent areas 310, 310′ may also be applied in embodiments of
In alternative embodiments, the light source 401 and the light-sensitive element 401′ may also be arranged on the other side of the nose, for example in the second side part 110′ of the support frame 120, or at another location, e.g. on the bridge of the nose, in that the support frame has an additional resting element there or does not have two discrete side parts 110 and 110′, but a continuous element expanding from the one side of the nose across the bridge of the nose to the other side of the nose.
In this context it shall also be noted that further embodiments of the apparatus for detecting at least one vital parameter may comprise an optoelectronic sensor arrangement for detecting the at least one vital parameter which is configured to determine said at least one vital parameter by means of light transmission and light remission, which may be conducted simultaneously or in an alternating or selectable manner in each case. In other words, the embodiments of
Comparative measurements have shown that the larger the influence of the arteries on the light transmission and light remission, the larger the amplitude A (see
Embodiments of the apparatus for detecting at least one vital parameter measure the vital parameters by means of the dorsal nasal artery and/or the angular artery (in the case of light transmission) and a derivation of same (for reflection measurement). Even though the dorsal nasal artery 23 and the angular artery 24 typically have essentially similar curves and similar positions with regard to the nose in all humans, the shape of the nose itself, for example with regard to its height and width, is very different from person to person. Thus, a specific spatial arrangement of the light source 1 and the light sensor 1′ in one side part (reflection measurement) or in both side parts (transmission measurement) of the support frame 120 may be optimally or at least well suited for measuring the vital parameter, whereas due to different nose shapes, the same arrangement of the light source 1 and the light-sensitive element 1′ in the one side part 110 and/or the second side part 110′ may provide less ideal results or even useless results.
Embodiments may therefore comprise, in the side part(s) of the support frame 120, a position and arrangement of the light source 1 and the light-sensitive element 1′ which is specific to the person, i.e. is adapted to the positions and the courses of the arteries, so as to enable optimum measurement in each case.
However, the pair of spectacles may also slide to a different position during wearing and/or may be placed into various positions of the nose when being taken down on or put on again, so that even with such person-specific adaptation of the position and arrangement of the light source and the light-sensitive element degradations of the quality of the measurement results may occur.
Further embodiments of the apparatus for detecting at least one vital parameter of a person comprise a multitude of light sources and a multitude of light-sensitive elements which are mutually allocated in pairs, for example, so that a light source and a light-sensitive element form a measurement pair by means of which a signal S (see
An embodiment of a method of detecting at least one vital parameter of a person by means of an optoelectronic sensor arrangement, (such as in
In general terms, a first step of the method comprises selecting a specific measurement pair of the three measurement pairs on the basis of the quality of one or more optoelectronic measurements, which may also be referred to as test measurements, so as to then employ the selected measurement pair for actually determining or detecting the vital parameter in a next step.
Step 810 comprises performing at least one optoelectronic measurement within the same wavelength range or wavelength for each of a plurality of measurement allocations of one light source among a multitude (3 in this case) of light sources and one of a multitude (3 in this case) of light-sensitive elements so as to generate at least one amplitude-dependent measurement result.
Step 820 comprises determining a measurement quality for each of the three or the multitude of measurement allocations on the basis of the respective at least one measurement result.
In step 830, the measurement allocation of the multitude of measurement allocations having the highest measurement quality is selected so as to then perform, in step 840, at least one optoelectronic measurement by means of the selected measurement allocation in order to determine the at least one vital parameter on the basis thereof.
With regard to the apparatus of
As was previously set forth with reference to
By putting on and taking off the pair of spectacles, or by moving the pair of spectacles on the bridge of the nose, the position of the selected first measurement allocation 1-1′ relative to the angular artery may change and result in a deterioration of the measurement results.
Further embodiments of the present method are therefore configured to monitor the quality of the measurement signals of the current or active measurement allocation 1-1′, for example to compare it with a threshold value. If the quality of the measurements of the active or currently selected measurement allocation 1-1′ falls below said threshold value, steps 810 to 830 may be performed again, for example, to check whether a different measurement allocation may now provide a higher measurement quality, and to then again perform step 840 for determining the vital parameters.
A further embodiment not only comprises, following step 820, selecting a measurement allocation for the following actual measurements, but also storing the various measurement allocations in an order of priority according to their quality levels, and instead of again performing steps 810 to 830 if the quality threshold value is fallen below by the active measurement allocation, the next or next best measurement allocation, according to the order of priority, is used as the active measurement allocation for the following measurements for determining the vital parameter. In the case of
Embodiments comprising a first number m of light sources that are spatially arranged in a row, and comprising a corresponding row of light-sensitive elements on the opposite side, enable compensating for any displacement of the pair of spectacles in this very direction. In the embodiment of
A planar arrangement of a first number of light sources as is shown, for example, in
A further embodiment will be described on the basis of
In embodiments, the light sources and light-sensitive elements may be arranged in arrays, e.g. in a 4×4 array as in
With regard to their planar arrangement and distribution, the light sources and light-sensitive elements are arranged, in particular, at those positions of the first side part and second side part of the support frame for which it is to be expected, if the pair of spectacles is placed normally on the nose, that at least one of the light paths (e.g. 180, etc) of the different measurement allocations will pass through the artery or will at least have as small a distance as possible to it, so as to achieve as high a quality as possible for measuring the vital parameters.
In further embodiments of the apparatus for detecting, the light sources and light-sensitive elements may be directly integrated, without components 710, 710′, into the first side part 110 or the second side part 110′.
Accordingly, this also applies to embodiments which are based on measurement by means of light remission.
Further embodiments may be configured to also measure the oxygen content of the blood. They will then comprise light sources that may be operated in a different light wave range and that are arranged, for example, next to or between light sources as are depicted in
In other words, in embodiments of the apparatus for detecting, a multitude of light sources may comprise a first subset of light sources configured to generate light of a first wavelength range, and a second subset of light sources configured to generate light of a second wavelength range different from the first one.
The term “measurement allocation” is generally used for allocations of light sources and light-sensitive elements. The term “measurement pair” designates the specific case where a light source is allocated to a light-sensitive element, e.g. for optical plethysmography, and the term “measurement triple” designates the specific case where a light-sensitive element has two light sources allocated to it which are operated at different wavelengths, e.g. for optical oximetry.
In embodiments, a suitable microcontroller, advantageously a digital signal processor 1005, may take over controlling the individual components of the arrangement as well as recording, processing and evaluating the waveforms resulting from the arrangement. The microcontroller, or digital signal processor, controls the LED driver circuit 1006, possibly the demultiplexer 1007, takes over distributing the signals generated to the individual light sources 1, 1a, and selecting, as was described with reference to
Downstream from the analog/digital converter 12, the digitized signal is received and processed by the microcontroller or the digital signal processor 1005. Subsequently, the signal is amplified by means of a circuit 1009, and by means of a peak detector 1010, the pulse is prolonged in terms of time so as to enable improved sampling. Finally, the signal is filtered using a circuit 1011. Thereafter, the plethysmographic signals—this depends on the number of wavelengths—are processed further by the microcontroller or digital signal processor 1005, and vital parameters are calculated from this signal or these signals or in combination with other physiological parameters. Embodiments of the measurement system or of the apparatus for detecting the at least one vital parameter comprise a driver circuit 1006 which may drive the light sources or light emitting diodes at a high light intensity or current, and may operate the light sources 1, 1a at very short pulses, so as to avoid high current consumption of the measurement system, and comprise a peak detector 1010 so as to enable reliable digital sampling of the analog plethysmographic signal.
In view of the above explanations, an object of various embodiments of the present invention is to implement detection of a pulse wave curve, and, derived therefrom, the oxygen saturation of the blood at a location that has so far not been useable, namely the nose, in a non-invasive manner which causes little impairment. Embodiments of the invention enable carrying the measuring means not only in environments of clinics, but also in one's personal surroundings and while being out and about, which is not possible with known finger clip pulse oximeters.
Embodiments of the sensor apparatus are worn like a normal pair of spectacles, so that the restriction on the patient's freedom of movement may be reduced to a minimum. The finger is not inhibited, and the patient is not limited in his/her freedom of movement. The limited or distorted evaluation of important vital parameters, e.g. heart rate, heart rate variability, oxygen content of the arterial blood, and pulse wave transmission time, which is encountered with conventional pulse oximeters and results from low blood circulation or vasoconstriction of the peripheral vessels, is substantially reduced when the nose is used as the place of derivation. The physiological reason for this is that the peripheral vessels, the arterioles, which run within the nasal septum, are direct derivations of the internal cervical artery and are therefore less strongly affected by vasoconstriction than the usual points of measurement, such as on the finger, toe or earlobe.
In other words, embodiments of the present invention enable implementing optical plethysmography and oxygen saturation of the blood derived from several wavelengths, which is integrated into the support frame of a pair of spectacles for metrological application on the bridge of the nose. The apparatus essentially comprises an active optical sensor unit, and the measurement is based on the transmission principle and/or the reflection principle. In yet other words, embodiments of the present invention represent a portable optical plethysmograph and an optical pulse oximeter, which are based on the transmission principle and/or the remission principle, in the form of a pair of spectacles. Accordingly, embodiments may also be referred to as “measurement apparatus for evaluating vital parameters by means of optical transmission or reflection plethysmography on the nasal bone” or “method for detecting vital parameters by means of optical transmission or reflection plethysmography on the nasal bone”.
The field of application of the invention is the field of preventive, monitoring and accompanying medical care for every-day use on a patient's body.
Further embodiments may also be referred to as an apparatus for detecting and evaluating vital parameters by means of optical plethysmography on the bridge of the nose while using transmissive and/or reflective signal acquisition, the apparatus comprising a sensor head which has light sources and light receivers integrated therein and is integrated, on the bridge of the nose, into the support frame of a pair of spectacles, the control and evaluation electronics unit, which is electrically connected to the sensor head and is powered by a battery or an accumulator, being arranged so as to be spatially separated therefrom.
Further embodiments of this apparatus have the shape of a pair of spectacles and evaluate vital parameters by means of optical transmission or reflection plethysmography.
Further developments of these embodiments comprise an optimated driver circuit that may operate light emitting diodes at a high level of light intensity and/or a large amount of current while generating very short light pulses so as to maximize the signal quality and to minimize current consumption.
Even further-reaching developments of these embodiments comprise a peak detector so as to enable reliable digital sampling of the analog plethysmographic signal.
Further embodiments comprise an arrangement of light emitting diodes and photodiodes as transmitters and receivers, which may be switched or selected via multiplexers and demultiplexers, as to be able to vary the position of the measurement area or the point of measurement, so as to thus be able to measure at a location as close to an artery as possible and to therefore be able to select or achieve optimum signal quality.
In addition, embodiments comprise a selection apparatus so as to find and select the optimum position, i.e. a position located as close to an artery as possible, by means of multiplexers and demultiplxers and the arrangement of light emitting diodes and photodiodes.
Depending on the circumstances, the embodiments of the inventive methods may be implemented in hardware or in software. Implementation may be on a digital storage medium, in particular a disk, CD or DVD having electronically readable control signals which cooperate with a programmable computer system such that one of the embodiments of the inventive methods is performed. Generally, the embodiments of the present invention thus also consist in software program products or computer program products or program products having a program code, stored on a machine-readable carrier, for performing one of the embodiments of the inventive methods, when one of the software program products runs on a computer or a processor. In other words, an embodiment of the present invention may thus be implemented as a computer program or a software program or program having a program code for performing an embodiment of an inventive method, when the program runs on a processor.
The processor here may be constituted by a computer, a chip card, a digital signal processor, or any other integrated circuit.
While this invention has been described in terms of several embodiments, there are alterations, permutations, and equivalents which fall within the scope of this invention. It should also be noted that there are many alternative ways of implementing the methods and compositions of the present invention. It is therefore intended that the following appended claims be interpreted as including all such alterations, permutations and equivalents as fall within the true spirit and scope of the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102009008604.8 | Feb 2009 | DE | national |
