EP1987444A2 - Procédé d'étalement de spectre pour déterminer des paramètres vitaux - Google Patents

Procédé d'étalement de spectre pour déterminer des paramètres vitaux

Info

Publication number
EP1987444A2
EP1987444A2 EP07711445A EP07711445A EP1987444A2 EP 1987444 A2 EP1987444 A2 EP 1987444A2 EP 07711445 A EP07711445 A EP 07711445A EP 07711445 A EP07711445 A EP 07711445A EP 1987444 A2 EP1987444 A2 EP 1987444A2
Authority
EP
European Patent Office
Prior art keywords
signal
signals
dark
light source
extraction
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.)
Withdrawn
Application number
EP07711445A
Other languages
German (de)
English (en)
Inventor
Andreas Tobola
Ulrich Vogl
Hans-Joachim Moersdorf
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.)
Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV
Original Assignee
Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV
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 Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV filed Critical Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV
Publication of EP1987444A2 publication Critical patent/EP1987444A2/fr
Withdrawn legal-status Critical Current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
    • A61B5/145—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue
    • A61B5/1455—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue using optical sensors, e.g. spectral photometrical oximeters
    • A61B5/14551—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue using optical sensors, e.g. spectral photometrical oximeters for measuring blood gases
    • 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
    • A61B5/103—Detecting, measuring or recording devices for testing the shape, pattern, colour, size or movement of the body or parts thereof, for diagnostic purposes
    • A61B5/107—Measuring physical dimensions, e.g. size of the entire body or parts thereof
    • A61B5/1073—Measuring volume, e.g. of limbs
    • 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
    • A61B5/7207—Signal processing specially adapted for physiological signals or for diagnostic purposes for noise prevention, reduction or removal of noise induced by motion artifacts
    • 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
    • A61B5/7235—Details of waveform analysis
    • A61B5/7253—Details of waveform analysis characterised by using transforms
    • A61B5/7257—Details of waveform analysis characterised by using transforms using Fourier transforms

Definitions

  • the present invention relates to a device for determining a vital parameter of a living being.
  • the method finds application in plethysmogram-based measurement methods (e.g., plethysmography, pulse oximetry) for the purpose of lower susceptibility to environmental light interference and electromagnetic interference.
  • Plethysmography is an optical method for obtaining a so-called plethysmogram, which provides information about the pulse rate and blood oxygen saturation of a subject.
  • a plethysmogram is a graphical representation of volume changes. Specifically, in this field of application, the volume changes of an arterial blood stream at a localized measuring site on the human body are recorded as the plethysmogram.
  • tissue is irradiated with light at a body site with arterial blood vessels. The patient is placed on a sensor that includes a light source and a photoreceiver so that the light passes through the tissue layer and the remaining light intensity strikes the photoreceptor.
  • Fig. 24 shows the basic Piellen structure of a device for detecting a plethysmogram.
  • a microcontroller (.mu.C) controls two LEDs of different wavelengths via two driver stages. In principle, a light source is sufficient to create a plethysmogram.
  • the LEDs shown in Fig. 24 emit light in the red and infrared regions.
  • the light emitted by the LEDs then passes through the tissue of the subject, in Fig. 24 this is exemplified as a finger.
  • the photosensor converts the optical signals into electrical signals and forwards them to processing electronics that amplify the signal, convert it analog-to-digital and feed it to the microcontroller ( ⁇ C).
  • the microcontroller determines from the digital signals supplied to it two plethysmograms, one plethysmogram per wavelength.
  • vital parameters such as the heart rate or the blood oxygen saturation of the subject can be determined, whereby in principle a single plethysmogram would suffice to determine the heart rate, two plethysmograms of light sources of different wavelengths are necessary for determining the blood oxygen saturation.
  • Pulse oximetry is a noninvasive method for measuring blood oxygen saturation (SpO 2 ) and heart rate (HR) using an optical sensor.
  • the oxygen saturation detected by the pulse oximeter is called the SpÜ 2 value.
  • Oxygen saturation is defined as the ratio of the concentration of oxygen-saturated hemoglobin molecules to the total hemoglobin concentration and is expressed as a percentage.
  • One component of the pulse oximeter is a sensor with two integrated light sources, which is similar to that of a plethysmograph, cf. Fig. 24. In the pulse oximetry is of at least Two plethysmograms were used to determine the color of the arterial blood. The color of the blood in turn depends on the oxygen saturation.
  • the wavelengths of the light sources With a clever choice of the wavelengths of the light sources, it can be shown that from the ratios of marked points in the plethysmogram a size can be obtained which correlates well with the oxygen saturation.
  • the spectra of the received signals of two light sources of different wavelengths are determined and the quotient of specific spectral values is formed. This quotient is then approximately proportional to the Sp ⁇ 2 value of the blood.
  • An essential quality feature when comparing pulse oximeters is the resistance to interference. Particularly problematic is the filtering of those unwanted signal components that are caused by the movement of the patient. Even with small movements, the amplitudes of the so-called motion artifacts can be greater than those of the pulse wave in the signal. If the signal is strongly overlaid with motion artifacts, this leads to a temporary malfunction of the devices with corresponding signaling of this problem. In the worst case, the devices do not detect the falsified measurement and do not emit a signal, so that the displayed measured values are mistaken for true. The quality of treatment of a patient may be significantly reduced due to incorrectly displayed measurements. Especially in the vicinity of operating theaters, the aforementioned distortions represent a major disadvantage of pulse oximeters.
  • the amount of interference in the plethysmogram thus depends heavily on the electronic devices or interferers used in the environment. Especially in the intensive medical care of patients, a variety of electronic devices and aids is used, so that the susceptibility of pulse oximeters and plethysmographs in intensive care environments is particularly given. On the other hand, especially in the area of intensive medical care, measurement errors of vital parameters such as the heart rate or blood oxygen saturation are extremely critical and can have serious consequences.
  • transmission and remission sensors have several LEDs (transmitters) and only one photodiode (receiver).
  • the tissue of the subject is thereby transilluminated by LEDs of different wavelengths and the photodiode receives the light of different wavelengths from the tissue.
  • TDMA concepts time division multiple access
  • ie time multiplexing are used in known pulse oximeters.
  • Each sensor LED is assigned a time slot in which it is switched on.
  • Fig. 25 illustrates this temporal sequence of signals. It can be seen that time slots of the same duration, which are separated by dark periods of the same duration, are assigned to the various LEDs one after the other.
  • Fig. 25 shows a schematic sequence with three different LEDs. Successively, the LEDs of different wavelengths light up, in Fig.
  • the bright periods of the LEDs are denoted by "LED 1", “LED 2" and “LED 3" for a short period of time Typical frequencies with which the light sources are driven
  • Current pulse oximeter By adding additional dark phases in which none of the LEDs are lit, indicated by "DARK" in FIG. 25, the signal portion caused by ambient light is attempted to be measured and then subtracted from the useful signal. Nevertheless, the results are often distorted by ambient light or high frequency surgery influences.
  • tissue is cut by means of high-frequency voltages. These high frequencies cause inductions in the pulse oximeter lines and may interfere with their function. The local influences can be largely suppressed because the sensors are protected against external radiation. Nevertheless, ambient light enters the envelope of the sensor.
  • the susceptibility to interference of current pulse oximeters and plethysmographs increases when the aforementioned interferers are present in their environment. Especially in operating rooms or intensive medical care stations, there is a variety of electronic devices or electronic interferers. That is why the susceptibility to interference of current pulse oximeters and plethysmographs increases in such environments. This significant disadvantage can result in serious consequences for subjects when measurement errors occur in such situations that can not be immediately identified as such.
  • EP 1374764 AI / WO 2002054950 A08 in which a basic circuit for measuring and detecting a plethysmogram is described and the signal processing described above is discussed in detail.
  • EP 208201 A2 / A3 in which the optical detection of a change in volume of a body part and an evaluation device for evaluating the optical signals is protected in principle. The method described there uses the changing external volume change of extremities, which is caused by the pulse and the associated blood pressure changes.
  • EP 341059 A3 a principle method for pulse oximetry is described which makes use of light sources (LEDs) of different wavelengths.
  • LEDs light sources
  • the tissue of the subject is irradiated with light of different wavelengths, the light signals recorded by means of optical sensors from the tissue and enhanced by a corresponding analog signal processing.
  • EP 314331 B1 a method of pulse oximetry also based on light of different wavelengths, is used to illuminate the tissue of a subject.
  • the optical signals obtained in this way are converted into electrical signals, from which a value of the conclusion about the blood oxygen saturation of the test subject is extracted.
  • EP 1254628 A1 the pulse oximeter protected here, is also designed to determine blood oxygen saturation, the crosstalk interference being additionally reduced by the method proposed here.
  • DE 692 29 994 T2 discloses a signal processor which receives a first signal and a second signal correlated with the first signal. Both signals have a desired signal component and an undesired signal component.
  • the signals can be picked up by the propagation of energy through a medium and by measuring an attenuated signal after transmission or reflection. Alternatively, the signals may be received by measuring energy generated by the medium.
  • the first and second measured signals are processed to receive a noise reference signal that does not include the desired signal components of the respective first and second measured signals.
  • the remaining unwanted signal portions of the first and second measured signals are combined to form a noise reference signal.
  • This noise reference signal is correlated with each of the undesired signal components of the first and second measured signals.
  • the noise signal is then used to remove the unwanted signal components in the first and second measured signals via an adaptive noise canceler.
  • An adaptive noise canceler can be seen in analogy to a dynamic multiple band rejection filter which dynamically alters its transfer function in response to a noise reference signal and to the measured signals to remove frequencies from the measured signals also present in the noise reference signal.
  • a typical adaptive noise canceler thus receives the signal from which noise is to be removed and a noise reference signal. The The output of the adaptive noise canceler is then the desired signal with reduced noise.
  • US 2005/0187451 describes a method for use in a signal attenuation measurement to determine a physiological parameter of a patient. Furthermore, a device is described for determining a physiological parameter of a patient from at least two signals which have passed through tissues of the patient and have been attenuated there. The two signals are multiplexed using a FOCDM (Frequency Orthogonal Code Division Multiplex) method. The method allows a separation of the two signals and a suppression of external interference.
  • FOCDM Frequency Orthogonal Code Division Multiplex
  • the object of the present invention is to provide a device and a method for determining vital parameters, such as e.g. to create the heart rate and blood oxygen saturation of an animal using an improved measurement concept for more efficient suppression of disturbances in order to increase the quality of treatment of patients.
  • a device for determining a vital parameter of a living being with a receiving device which is adapted to receive and to convert repetitive optical signals into electrical signals, wherein an optical signal has sequences and a sequence at least two Healing periods in which a transmission light source assumes an on state, and has at least one dark period in which no transmission light source assumes an on state, and the at least two heat durations are arranged unevenly in a sequence.
  • the device comprises an extraction device for extracting information about the vital parameter from the received signal, wherein the Extractor is adapted to extract based on the information on the arrangement of the healing periods in the sequence, a value indicative of the vital parameter size.
  • a transmitting device for generating a light signal for coupling into a body part which is designed to generate a drive signal with a driver device, wherein the driver device is designed to generate a sequence of repeating sequences and one Sequence has at least two healing periods in which the drive signal causes a single state of the light source, at least one dark period of time has up, in which the drive signal causes an off state of all light sources and wherein the at least two healing periods are arranged irregularly in the sequence and at least one light source for generating a light signal for coupling into a body part based on the drive signal.
  • the core idea of the present invention is a light source whose light is coupled into a body part of a subject, and the signal is received by a photodetector, to control so that it takes the state of being at irregular intervals within a repeating sequence.
  • the irregularity causes a widening in the spectral range of the signal.
  • the additional borrowed spectral components of the light signal create additional noise immunity.
  • two spectral lines of the same height are created. Since the probability that both spectral components are disturbed at the same time is less than the probability that a single spectral component is disturbed, a gain in diversity results in the frequency domain.
  • This diversity gain can be realized by a corresponding signal processing, so that is achieved by the irregular driving of the light sources, a higher noise immunity and thus greater reliability of the measurement of a vital parameter. Furthermore, a so-called spreading profit arises. Due to the irregular driving, the energy of the desired signal is distributed uniformly over several frequency components. Since the irregularity is known, these energy components can be coherently superimposed again in the receiver. Noise components that are at the same frequencies are also superimposed in the receiver, but since these are independent of each other, an incoherent superimposition occurs here, so that a profit is generated for the useful signal. A narrow-band interferer, which is superimposed on the useful signal only at a frequency component, experiences in the receiver a spectral widening analogous to that of the useful signal in the transmitter, since in both cases signal components are combined at irregular times.
  • the irregular driving at the light source corresponds to a spread spectrum modulation.
  • spread spectrum modulation in combination with a downstream adaptive filtering signal components are reduced, which are due to ambient light influences or to electromagnetic interference sources (eg high-frequency surgery).
  • a subsequent signal processing also allows a particularly efficient measurement of the blood oxygen saturation and the heart rate of a patient, which can be reliably measured with the present method even with low arterial Blutvolumenpulsa- tion and movement of the patient.
  • the increased reliability of the measurement thus directly causes an increase in the quality of treatment of a patient.
  • an advantage of the present invention is that the increased reliability of the measured values of a pulse oximeter, in particular in critical environments, such as operating theaters or intensive care units, results in higher recovery rates. Opportunities and more efficient treatments will be enabled.
  • Fig. 1 is a schematic block diagram of the preferred embodiment
  • Fig. 2 a schematic representation of the irregular
  • FIG. 2b shows a regular arrangement of the bright-time periods according to conventional pulse oximeters
  • FIG. 3 block diagram of an implementation of the preferred embodiment
  • Fig. 5 is a schematic representation of a spectrum of a signal in the transmission band
  • FIG. 9 is a schematic representation of the spreading disturbance and despreading in the frequency domain.
  • FIG Fig. 9a schematic representation of the spectrum in the baseband
  • 11 shows an illustration of two exemplary signal curves for the dark duration or the ambient light measurement
  • FIG. 12 Exemplary transfer function of an extraction filter with 15 dB attenuation and 100 Hz suppression; FIG. Magnification in the range of 100 Hz.
  • FIG. 13 shows exemplary waveforms of the light emitting channels from which the ambient light signal has been subtracted, the magnification shows the reference signal.
  • FIG. 14 Schematic representation of the block formation for further signal processing, 1 B corresponds to the block length, l a is a measure of the overlap.
  • FIG. 15a Exemplary signal profile of an input signal, and of the low-pass filtered direct signal (DC component)
  • FIG. 15b Exemplary signal course of the high-pass filtered signal (AC component)
  • FIG. 16 Model of the adaptive filter with the input quantities left and output variables on the right, the reference signal being characterized by W A C.
  • Fig. 17 Exemplary course of an Kaiser-Bessel window with a block length of 256 points.
  • Fig. 18 exemplary spectral profile of the normalized useful signals for the two Hellsendekanäle red and infrared
  • FIG. 19 an exemplary representation of the two spectra for red and infrared transmission channels, wherein spectral values of the same frequencies are plotted against each other.
  • 20a is a schematic representation of the least squares fit method for minimizing a vertical distance to a straight line
  • Fig. 20b is a schematic representation of the total least squares fit method for minimizing the actual distances to a straight line.
  • FIG. 21a exemplary course of the quotient between the red transmission channel and the infrared transmission channel at four different times k2
  • FIG. 21b shows an exemplary course of a reference spectrum determined using the method of the Complex Total Least Squares Fit method.
  • FIG. 22 shows an exemplary spectrum of a signal curve in which the amplitudes of the disturbance are greater than the amplitudes of the pulse wave
  • Fig. 23 exemplary characteristic of a calibration function
  • Fig. 24 is a principle block diagram of the hardware of a pulse oximeter according to the prior art
  • FIG. 25 shows a schematic representation of a time division multiplex method (TDMA).
  • TDMA time division multiplex method
  • the receiver 100 has a receiving device 105 which receives sequences of optical signals at its input 110 and converts these at its output 115 into converted electrical signals spend again.
  • the extraction device 120 receives the electrical signals of the receiving device 105 at its input 115, extracts therefrom a measure of a vital parameter, such as a heart rate or a blood oxygen saturation, and outputs this at its output 125.
  • the extraction device 120 receives a clock at a control input 130, via the control input 130, the extraction device 120 can optionally also contain additional information, received, for example, in the form of binary code words containing information about the timing of the time periods associated with a transmission channel.
  • the clock can also be generated by the extraction device 120 itself, for example by an analysis of the received signal or by an integrated clock generator.
  • the device described has a control device 140, which via the control input 130 of the extraction device 120, this can specify a clock.
  • the controller 140 may also specify a clock to the transmitter. In this way, synchronization between transmitter 150 and receiver 100 is achieved.
  • This clock is then optionally passed on via a control connection 155 to a driver device 160.
  • the driver 160 provides an output 165 with a driver signal that is passed to a light source 170.
  • the light source 170 converts the drive signal into an optical signal and provides this at an output 175.
  • the optical signal can then be coupled into a body part of the subject 185 via a fastening device 180.
  • the driver device 160 controls the light source 170 with repetitive electrical signals which contain sequences, the sequence being light-time durations, in which the light source 170 assumes the on state, and dark-time periods in which the light source 170 assumes the off state , composed.
  • the driver device 160 is designed in such a way that the bright-time durations within the sequence are irregular. This irregularity of the bright-time durations is shown schematically in FIG. 2a.
  • Fig. 2a shows a repetitive sequence of duration ⁇ T.
  • one ne light source Hi twice an on state This is indicated in Fig. 2a by the entries Hi.
  • the light source is turned off.
  • FIG. 2b shows a sequence of a conventional pulse oximeter in which two light sources are driven.
  • TDMA time-division multiplex method
  • each light source occupies the on state for a timeslot. This is indicated in Fig. 2b by Hi and H 2 .
  • Di and D 2 in Fig. 2b D stands for "DARK"
  • neither of the two light sources should have assumed a single state, and the comparison of Figs 2a and 2b illustrates the crucial irregularity in Fig. 2 the arrangement of the light-time durations of the present invention.
  • Fig. 3 shows an implementation of the preferred embodiment.
  • a spread spectrum modulation 300 is converted into an optical signal by an LED driver stage 305.
  • the LED driver 305 in accordance with the received spread spectrum modulation, couples light signals into a tissue 310 (e.g., a finger), whereupon the light signals are modulated on their way through the tissue and subsequently received by a photoreceptor 315.
  • the photoreceptor 315 converts the received optical signals into electrical signals and feeds them to an A / D converter 320 which converts the analog signal into a digital signal.
  • a / D converter 320 Downstream of the analog-to-digital converter 320 is a spread spectrum demodulator 325.
  • the signal is adaptively filtered 330 and then Fourier. 335.
  • a spectral mask 340 is now applied to the spectrum of the signal, whereupon the subject's heart rate can be determined and then output at the output 345.
  • the so-called “Complex Total Least Squares Fit” method 350 a variance of the difference of the different spectra, which were measured for light of different wavelengths, can now be determined via a statistical analysis in the frequency domain and as a reliability measure at the output are output 355th to the output value that the "Complex Total Least Squares Fit” device delivers 350, can now have a calibration function 360, an associated blood saturation value (Sp ⁇ 2 ⁇ value) at the output 365 to be output.
  • a modulation method consisting of the modulator 300 and the demodulator 325 is needed.
  • the spread spectrum method is used. This modulation method is based on the fact that the spectrum of the baseband signal is spread or widened due to the irregularity of the bright-time durations. This effect is illustrated by the figures 4 to 9.
  • 4 initially shows a spectrum
  • amplitude modulation the spectrum of the baseband signal is shifted to a frequency range better suited for transmission.
  • each transmit channel which is understood to mean the transmitted light signals of one wavelength, is assigned to a previously calculated, so-called chip sequence.
  • a chip sequence consists of a finite sequence of ones and zeros, which are typically clocked at a frequency one hundredfold higher than that of a TDMA concept.
  • the clock frequency is around 3kHz.
  • the chip sequences must fulfill certain properties in order to achieve the desired spreading effect of the interference signal and to enable the reconstruction of the plethysmograms and of the ambient light channels.
  • the chip sequences must be orthogonal in order to be able to realize a channel separation in the demodulation and thus enable demodulation without crosstalk.
  • FIG. 6 shows a schematic representation of two orthogonal chip sequences, the length of a chip sequence being equal to 101 chips.
  • FIG. 6 shows a time-ray with a duration of 101 chip durations. Over these 101 chip durations, the values of second chip sequences c (k) are plotted. In the diagram, the two chip sequences are distinguished by dashed or solid lines. Whenever a chip sequence assumes the value 1, this means that the associated light source is brought into the on state.
  • FIG. 6 shows very clearly that the two chip sequences are orthogonal, ie that the two associated light sources never simultaneously take state.
  • FIG. 6 shows that the two chip sequences never assume the value 1 at the same time.
  • FIG. 7 shows the spectrum, ie the frequency range of one of the chip sequences shown in FIG. 6. It can clearly be seen in FIG. 7 that the spectrum of such a sequence is uniformly distributed, ie the spectrum is composed of equidistant identical values.
  • the high DC component which is represented by the excessive value at the frequency 0, can be explained by the fact that the chip sequence can only assume the values 0 and 1. As a result, the sequence is not averaging.
  • the spectrum of a chip sequence can thus be regarded as a "comb" of equidistant carriers of the same amplitude. "The spectral equal distribution of a chip sequence has the consequence that a narrowband interferer is spread into a broadband noise after demodulation Realization of the preferred embodiment guide example, as shown in Fig. 3, driven with the chip sequences shown in Fig. 6.
  • Fig. 8 shows the schematic representation of the signal of Fig. 4 in the transmission band
  • the baseband signal as shown in Fig. 4, retains its spectral shape but its energy is distributed to many frequencies. This process is also known as spreading. If the signal shown in FIG. 8 is now disturbed by a narrow-band interferer, it undergoes a spread during the demodulation, whereas the energy components of the signal from FIG. 8 again superimpose coherently in the baseband.
  • the demodulation corresponds to a new multiplication with the corresponding chip sequence. The result of the multiplication is then summed over a chip sequence length. If a received signal is thus multiplied by one of the chip sequences as illustrated in FIG. 6, it can easily be seen from FIG.
  • FIG. 9a) shows the spectrum of a baseband signal.
  • Fig. 9b) shows the spectrum of a chip sequence, which is ideally equally distributed spectrally.
  • FIG. 9c) shows the spread baseband signal, which now has energy components at each individual frequency of the chip sequence. The energy of the baseband signal was spread to the frequencies contained in the chip sequence. In the implementation according to the invention, the signal in this form is received from the tissue by the photosensor, the actual useful signal was then modulated onto the spread signal by the tissue.
  • Fig. 9c) also shows two disturbances, "Fault 1" and "Fault 2".
  • FIG. 9 d) shows the spectrum of the signal after demodulation or after despreading. It can be seen that the baseband signal has been reconstructed and the additional frequencies of the interfering signals in baseband have been added. Fig. 9d) further shows that the remaining frequencies of the disturbance have significantly lower amplitudes than the original disturbance itself, which is due to the spreading of the interfering signal.
  • Legendre episodes are chip sequences that meet the required characteristics and have good auto and cross-correlation properties.
  • the sequences modulate two bright and two dark transmit channels in the considered implementation of the preferred embodiment.
  • the spectral properties of all sequences are identical and fulfill the required uniform distribution in the spectral range.
  • a total of four episodes are considered, with the four following are mutually orthogonal, which means that no two sequences take the value 1 at the same time.
  • the use of other consequences is also conceivable.
  • the property of the irregularity of the bright periods is to be emphasized; this does not require that only one sequence can have one bright time duration at a time.
  • Two of the four sequences are used in one implementation of the preferred embodiment to drive two LEDs of different wavelengths (red and infrared), the two remaining sequences serve to modulate ambient light channels, ie they correspond to dark channels.
  • the LEDs are now controlled as monochromatic light sources.
  • the LED light modulated with the chip sequences passes through a tissue layer and undergoes a corresponding attenuation depending on the wavelength of the light source.
  • the radiation of the LEDs attenuated by the tissue impinges, where it is converted into a proportional photocurrent and then scanned with an analog-to-digital converter 320 in synchronism with the clock of the modulator 300, taking into account the Nyquist theorem (sampling theorem).
  • the synchronism between the modulator in the transmitter and the AD converter or demodulator in the receiver can optionally be solved by a control device, which controls both transmitters and receivers via control connections.
  • the synchronously sampled signal is supplied to the spread spectrum demodulator 325.
  • the spread spectrum demodulator 325 uses demodulation to separate the signal of the photoreceiver into individual channels. In a practical implementation, these are two pulse channels for red and infrared LEDs, as well as two channels for the measurement of ambient light.
  • Fig. 10 shows two exemplary waveforms, the lower of the red LED and the upper one corresponds to the infrared LED. In FIG.
  • both signals are superimposed by a higher-frequency signal component originating from the test person's pulse signal, that both signals have a high DC component and that both signals have a low-frequency interference component which is due, for example, to changes in ambient light due to movements of the subject could have originated.
  • Fig. 11 shows two exemplary waveforms for the two dark channels. These two signals also show the high-frequency component which originates from the test person's pulse signal as well as a disturbance component attributable to ambient light changes.
  • the DC component in FIG. 11 is correspondingly lower than the DC component in FIG. 10, since the two light sources are switched off during the dark channel phases.
  • the average of the two ambient light channels is subtracted from the two light transmission channels in order to remove the low-frequency portion of ambient light lying below the two sampling frequencies from the measured signal.
  • a so-called matted filter (English: adapted filter) is used for each chip sequence to extract the transmission channels from the received signal.
  • a matched filter is a realization of the spread spectrum modulator 325 of FIG. 3 and can be described as a mathematical operation with a chip sequence.
  • the sensor signal is cyclically multiplied by the chip sequence and the result is summed over a respective chip sequence length. In the implementation of the preferred embodiment described herein, these are the respective Legendre sequences.
  • the Matched Filter mathematically realizes a scalar sample between the chip sequence and the receive vector, ie the sampled receive signal. Sender and receiver are synchronized.
  • the scalar product leads to a blockwise despreading of a transmission channel into baseband.
  • the power frequency is 50Hz, so the fundamental power (or intensity) is at 100Hz, and its harmonics are at multiples of 100Hz.
  • the attenuation of the extraction filter in the stopband is insufficient. Due to this finding, the frequencies corresponding to a multiple of 100 Hz can be suppressed by adjusting the characteristics of the extraction filter (combined filter).
  • FIG. 12 shows, by way of example, a transfer function of an extraction filter with 15 dB attenuation, in which additionally the interferers at multiples of 100 Hz are suppressed.
  • the extraction filter thus already contains a low-pass filter necessary for sub-sampling, and at the same time a matched filter for despreading the spread signal from the transmission band into the baseband.
  • a filter that performs a subsampling reaction. is also called a sub-sampler
  • the matched filter for despreading the spread signal is also called a correlator, since it correlates a given chip sequence with the received signal.
  • the extracted and subsampled signals are present.
  • the degree of undersampling depends on the chip sequence length. For each chip sequence length, a sample (sample) of the useful signal is produced by the matched filter.
  • a plurality of orthogonal chip sequences By using a plurality of orthogonal chip sequences, a plurality of channels are produced during a chip sequence duration. In the preferred embodiment according to the invention there are four channels, two bright transmission channels of the red and infrared LEDs, and two dark transmission channels, during which none of the transmission light sources assumes an on status, and the used for ambient light and noise compensation.
  • the interferences above the useful band ie disturbances above half the sampling frequency
  • the attenuation of the interference above half the sampling frequency depends on the chip sequence length. In the implementation of the preferred embodiment of the present invention, a chip trace length of 101 chips has been chosen, resulting in 15 dB attenuation for noise above half the sampling frequency.
  • the filter realizes an additional attenuation of all frequencies which are multiples of 100 Hz.
  • Fig. 12 shows an exemplary transfer function of an extraction filter.
  • the useful signals are in baseband.
  • a reference signal for the adaptive Filter 330 is the output side of the spread spectrum demodulator 325 downstream.
  • an average value is first formed from the dark channels, which is then subtracted from the light emitting channels.
  • Legendre sequences of length 101 chips are used. This realization resulted in an optimal weighting of the dark channels from 47.5% to 52.5%.
  • the band is below half the sampling frequency, the useful band.
  • the band exists above this frequency, the transmission band.
  • Disturbance-related frequency components that fall into the useful band can be removed by means of dark-phase subtraction from the two useful signals (bright-emitting channels of the red and infrared LEDs).
  • the signals of these frequencies are equal both in phase and in amplitude, and therefore do not occur in the difference of the two dark channels, the reference signal.
  • An interferer in the useful band (or baseband) accordingly gives 0 for the reference signal.
  • An interferer in the useful band could be a light source which is detected by the tissue from the photosensor and whose intensity is modulated with the volume changes of the arterial blood.
  • these components should not be filtered out of the useful signal since they contain the desired information (the pulsatile component).
  • an interferer could fall into the transmission band.
  • the attenuation of the extraction filter starts, which initially leads to the disturbance being attenuated falling into the useful band. In the implementation of the preferred embodiment, this attenuation is 15 dB.
  • signals of these frequencies experience a phase shift that is different for each channel.
  • the difference between the two dark transmit channels does not result in the cancellation of these signals, but rather in a signal whose frequency components contain the mirrored frequencies of the interferer from the transmission band.
  • This signal now serves as a reference signal to an adaptive filter 330 to also reduce the remaining noise from the transmission band.
  • the ambient light subtraction thus removes the interferers from the useful band, but also contains phase-shifted interference components from the transmission band. After the disturbances from the transmission band have been attenuated by the extraction, portions of this interference are now fed back to the useful signal by the ambient-light subtraction. This does not give the full attenuation for the interference signals from the transmission band, but a lesser value.
  • the attenuation by the extraction filter is initially 15 dB, which however is reduced again by 3dB by the ambient light subtraction, so that a total attenuation of 12 dB results for interferers from the transmission band.
  • Fig. 13 shows two exemplary waveforms for the two transmit channels, red and infrared LEDs, from which the ambient light signal has been subtracted. Furthermore, an exemplary reference signal is shown enlarged in FIG. 13.
  • a block formation for the individual signals takes place first.
  • the signals are divided into blocks of equal length, where the individual blocks overlap.
  • Fig. 14 illustrates the block formation for further signal processing.
  • blocks of length 1 B are formed from the samples of a useful signal, with all l a samples forming a new block.
  • the useful signals are then fed to a crossover.
  • the purpose of the crossover is to filter the DC component and the pulsatile component from the input signals.
  • the crossover frequency of the crossover is approximately at 0.5 Hz.
  • Fig. 15a shows the exemplary course of an input signal which is supplied to the crossover network. Furthermore, the low-pass filtered component (DC component) of the input signal is shown in FIG. 15a.
  • Fig. 15b shows the associated high-pass component (AC component) of the input signal.
  • the further signal processing refers only to the high-pass component of the input signal.
  • the high-pass filtered useful signals are now supplied to an adaptive filter 330.
  • the object of this filter which is also called Interference Canceller, is to remove interferences that were in the transmission band and have been mirrored attenuated into the useful band after the extraction, cf. Fig. 9d.
  • the reference signal was extracted containing the frequencies of the disturbance in the useful band.
  • the reference signal differs in phase and amplitude from the interference superimposed on the useful signals.
  • the task of the adaptive filter is therefore to filter out the unwanted image frequencies based on the reference signal from the useful signals.
  • a disturbance signal is constructed from the reference signal that comes as close as possible to the disturbance superimposed on the useful signal.
  • To determine the coefficients for the adaptive filter 330 there are several mathematical drive. A known method would be to choose the coefficients of the adaptive filter 330 such that the deviation between the reference signal and the useful signal is minimized. To determine the coefficients, the Complex Total Least Squares Fit method should also be mentioned here.
  • FIG. 16 shows the model of the adaptive filter with the input variables vv A r and w A ⁇ for the two input signals of the bright and infrared light emitting channels, where A indicates that the input signals are high-pass filtered.
  • the reference signal is also high-pass filtered as W A C , and forms the basis for determining the adaptive filter coefficients ⁇ r and ⁇ ⁇ .
  • the adap- tive filter first reconstructs an interfering vector, which is denoted by w s r and iv S i in FIG. 16. These interference components are then subtracted from the useful signals, so that the output signals of the adaptive filter are the useful signals y.
  • the input signals are transformed into the frequency domain by means of the Fourier transformation. Due to the block formation, unwanted side effects occur in the frequency domain. A block formation is to be equated, with a multiplication of a rectangular pulse, which just fades out the block considered from a received signal with the received signal itself. If the Fourier transformation is now applied to this block, then a convolution of the Fourier transformation is obtained in the frequency domain. transformed square pulse (Sinc function) with the actual spectrum of the sequence of received signal samples. In order to reduce the unfavorable effects caused by the convolution with the sinc function in the frequency domain, the block of received signal samples in the time domain is multiplied by a window function. which has a narrower spectrum than the sinc function. In the implementation of the preferred embodiment, an Kaiser-Bessel function is used for this purpose. In Fig. 17, the waveform of an Kaiser-Bessel window is exemplified.
  • the two wanted signals are normalized. Subsequently, the Fourier transformation takes place. After the Fourier transform, the spectra can be represented in different views, e.g. their course over time or over the frequency.
  • FIG. 18 shows two exemplary spectra of the normalized signals from the red and infrared light emitting channels. The spectrum shows a signal in good conditions, i. with relatively little disturbance.
  • the application of a spectral mask 340 for the determination of the heart rate, is carried out in a next signal processing step.
  • the Fourier transformation of the two signals from the Hellendekanälen initially provides two spectra. If the two signals were undisturbed, one of the two spectra would be represented as a linear combination of the other. However, since the two spectra are faulty, they can not initially be interconverted by a linear combination.
  • FIGS. 20a and 20b are intended to illustrate the procedure for the total least squares fit method.
  • the actual distance of a point to a straight line is minimized.
  • This approach initially leads to an overdetermined system of equations.
  • the overdetermined system of equations can be solved by a singular value decomposition, in order to find a solution corresponding to the Total Least Squares Fit method.
  • the singular value decomposition With the singular value decomposition, the matrix that represents the overdetermined linear system of equations is first decomposed. This results in a matrix containing on its diagonal the singular values of the system of equations.
  • this matrix is reduced to rank 1, thus reducing the problem to a solvable linear system of equations.
  • a solution line is drawn, it is located in the middle between see two other lines that define the range of valid slopes, resulting from reference measurements of SpO2 values define.
  • the slope of this line now represents a measure of the blood oxygen saturation of the subject.
  • a reference spectrum can now be determined from the linear equation system, which was determined with the help of the singular value decomposition.
  • the ascertained slope of the straight line of origin may initially be falsified if a disturbance of a higher magnitude
  • the function of the spectral mask 340 can be described as follows. In principle, it is a spectral method that searches the Fourier coefficients of the pulse signal in the spectrum to zero all coefficients that do not belong to the pulse signal. The principle of the spectral mask is based on differentiating the frequency components of the pulse wave from those of other interferers.
  • the algorithm of the spectral mask is basically a binary mask with the elements ⁇ 0, 1 ⁇ , with which the spectrum is multiplied by points, so as to suppress the Fourier coefficients not belonging to the pulse signal.
  • FIG. 21a shows the exemplary course of the quotient from two spectra of the signal profiles of the bright transmission channels.
  • FIG. 22 shows by way of example a spectrum of a signal which is disturbed by interference signals whose amplitudes are greater than the amplitudes of the actual pulse wave.
  • the quotient of two spectra is undefined at the frequencies of a disturber and has no relation to the blood oxygen saturation of a subject. Without the spectral mask, dominant perturbations as shown in FIG. 22 would result in a false blood oxygen saturation value. Studies have shown that such dominant disturbances are mostly least in both spectra, ie in the spectrum of the red signal as well as in the spectrum of the infrared signal. This has the consequence that quotients of the value 1 occur during quotient formation. A quotient of the value 1 corresponds to a blood oxygen saturation value of about 80%. It is now the task of the spectral mask to distinguish the frequency components of the pulse wave from those of the interferers.
  • the spectral mask has an algorithm of harmonic relationship.
  • the method of the harmonic relationship is based on findings from investigations of numerous pulse signals on their spectral properties.
  • the fundamental finding is the harmonic relationship of the three relevant frequencies f g of the fundamental, f o i of the first harmonic and f O2 of the second harmonic. It is also known that the second harmonic is at twice the frequency of the fundamental, and that the third harmonic is at three times the frequency of the fundamental. Based on this relationship, a mask can now be created which fades in the frequency range in each case the frequency components of twice and three times the frequency of a fundamental frequency, ie has a 1 at these points, and hides all other frequencies, ie has a zero at these points.
  • the heart rate can now be determined by the position of the spectral mask.
  • the heart rate is output at the output 345.
  • the variance is used as an indicator of excessive perturbation that prevents the calculation of vital signs within the specified tolerance.
  • This variance can then be output at output 355 as shown in FIG become.
  • the Complex Total Least Squares Fit method is followed by a 360 calibration function.
  • the slope of the line of origin determined by the Complex Total Least Squares Fit method, which is representative of the subject's blood saturation value, is passed to a 360 calibration function.
  • the calibration function directly assigns the obtained slope values to Sp ⁇ 2 values (blood saturation values).
  • the respective Sp ⁇ 2 values are then output at output 365 as shown in FIG.
  • Fig. 23 shows an exemplary characteristic of a calibration function. It can be seen how ratios (ratio) are assigned to blood saturation values (SpO 2 values).
  • the characteristics of the calibration function are determined empirically using reference measurements.
  • the advantage of the present invention is that the spread spectrum modulation tailored to the field of application of plethysmography and pulse oximetry and the combination of the specially adapted adaptive filtering significantly improves the reliability of the plethysmograms, as well as effective filtering of ambient light interferences and disturbances by electromagnetic fields (eg - quenz surgery).
  • a further advantage is that by using the singular value decomposition for calculating the Sp ⁇ 2 values from the complex spectra, a reliability measure can likewise be extracted in the form of a variance and used to assess the quality of the result, or a malfunction is reliably detected can be.
  • An additional advantage is that with the device according to the invention for measuring Substance saturation of the heart rate, even with low arterial blood volume pulsation during movement of the patient can be reliably measured.

Landscapes

  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Medical Informatics (AREA)
  • Surgery (AREA)
  • Biophysics (AREA)
  • Pathology (AREA)
  • Engineering & Computer Science (AREA)
  • Biomedical Technology (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Veterinary Medicine (AREA)
  • Molecular Biology (AREA)
  • Public Health (AREA)
  • Animal Behavior & Ethology (AREA)
  • General Health & Medical Sciences (AREA)
  • Cardiology (AREA)
  • Physiology (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Optics & Photonics (AREA)
  • Dentistry (AREA)
  • Oral & Maxillofacial Surgery (AREA)
  • Measurement Of The Respiration, Hearing Ability, Form, And Blood Characteristics Of Living Organisms (AREA)

Abstract

L'invention vise à déterminer un paramètre vital d'un être humain. Le dispositif selon l'invention comprend un équipement de réception (105) et un équipement d'extraction (120). L'équipement de réception (105) est conçu pour recevoir des signaux optiques (110, 175) répétitifs. Le signal optique présentant des séquences et une séquence d'au moins deux périodes lumineuses pendant lesquelles une source de lumière d'émission passe en mode Marche, et au moins une période sombre pendant laquelle aucune source de lumière d'émission ne passe en mode Marche, les deux périodes lumineuses ou plus étant réparties de manière non uniforme dans une séquence. Le dispositif selon l'invention présente également un dispositif d'extraction (120). Le dispositif d'extraction (120) extrait des informations sur le paramètre vital issu d'un signal de réception, le dispositif d'extraction (120) est conçu pour extraire, sur la base de l'information relative à la disposition de la période lumineuse dans la séquence, une valeur d'une grandeur donnant une indication du paramètre vital.
EP07711445A 2006-02-20 2007-02-06 Procédé d'étalement de spectre pour déterminer des paramètres vitaux Withdrawn EP1987444A2 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE102006007879 2006-02-20
DE102006022120A DE102006022120A1 (de) 2006-02-20 2006-05-11 Spreizspektrumverfahren zur Bestimmung von Vitalparametern
PCT/EP2007/001002 WO2007104390A2 (fr) 2006-02-20 2007-02-06 Procédé d'étalement de spectre pour déterminer des paramètres vitaux

Publications (1)

Publication Number Publication Date
EP1987444A2 true EP1987444A2 (fr) 2008-11-05

Family

ID=38329354

Family Applications (1)

Application Number Title Priority Date Filing Date
EP07711445A Withdrawn EP1987444A2 (fr) 2006-02-20 2007-02-06 Procédé d'étalement de spectre pour déterminer des paramètres vitaux

Country Status (4)

Country Link
US (1) US8398557B2 (fr)
EP (1) EP1987444A2 (fr)
DE (1) DE102006022120A1 (fr)
WO (1) WO2007104390A2 (fr)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2285271B1 (fr) 2008-06-16 2011-09-07 Koninklijke Philips Electronics N.V. Surveillance d'un paramètre vital d'un patient avec un schéma de modulation « in situ » pour éviter une interférence
US10656009B2 (en) * 2014-07-16 2020-05-19 Verily Life Sciences Llc Context discrimination using ambient light signal
DE102014225483B3 (de) * 2014-12-10 2016-05-04 Gert Küchler Verfahren und Gerät zur Bestimmung mindestens eines physiologischen Parameters
DE102015000125A1 (de) * 2015-01-07 2016-07-07 Seca Ag Verfahren und Vorrichtung zur Ermittlung und Auswertung von Messdaten
US20220241025A1 (en) * 2021-02-02 2022-08-04 Medtronic Navigation, Inc. Systems and methods for improved electromagnetic tracking

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20020136264A1 (en) * 2001-03-20 2002-09-26 Herleikson Earl C. Spread spectrum measurement device

Family Cites Families (24)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3524354C1 (de) * 1985-07-08 1987-01-15 Wienert Volker Vorrichtung zum Erstellen eines Venenverschluss-Plethysmogramms
US4807631A (en) * 1987-10-09 1989-02-28 Critikon, Inc. Pulse oximetry system
JPH06169902A (ja) * 1988-05-05 1994-06-21 Sentinel Monitoring Inc パルス式非侵入型オキシメータとその測定技術
GB9027234D0 (en) * 1990-12-15 1991-02-06 Harris Pharma Ltd An inhalation device
US5349952A (en) * 1991-03-05 1994-09-27 Sensormedics Corp. Photoplethysmographics using phase-division multiplexing
RU2144211C1 (ru) * 1991-03-07 2000-01-10 Мэсимо Корпорейшн Устройство и способ обработки сигналов
US5632272A (en) 1991-03-07 1997-05-27 Masimo Corporation Signal processing apparatus
US6714803B1 (en) * 1991-09-03 2004-03-30 Datex-Ohmeda, Inc. Pulse oximetry SpO2 determination
US5355880A (en) * 1992-07-06 1994-10-18 Sandia Corporation Reliable noninvasive measurement of blood gases
EP0638869B1 (fr) * 1993-08-13 1995-06-07 Siemens Aktiengesellschaft Procédé d'analyse spectrale à haute résolution pour oberservations à plusieurs canaux
US5503148A (en) * 1994-11-01 1996-04-02 Ohmeda Inc. System for pulse oximetry SPO2 determination
US5853364A (en) * 1995-08-07 1998-12-29 Nellcor Puritan Bennett, Inc. Method and apparatus for estimating physiological parameters using model-based adaptive filtering
US5835712A (en) * 1996-05-03 1998-11-10 Webmate Technologies, Inc. Client-server system using embedded hypertext tags for application and database development
EP0934021A2 (fr) * 1996-10-24 1999-08-11 Massachusetts Institute Of Technology Capteur d'annulaire surveillant un patient
US5921921A (en) * 1996-12-18 1999-07-13 Nellcor Puritan-Bennett Pulse oximeter with sigma-delta converter
EP0971625B1 (fr) * 1997-04-03 2013-08-21 National Research Council Of Canada Procede permettant d'evaluer la viabilite de tissus par spectroscopie en proche infrarouge
US6002952A (en) * 1997-04-14 1999-12-14 Masimo Corporation Signal processing apparatus and method
JP2002516689A (ja) * 1998-06-03 2002-06-11 マシモ・コーポレイション ステレオパルスオキシメータ
JP2001308710A (ja) * 2000-04-21 2001-11-02 Sony Corp 変調回路およびこれを用いた画像表示装置ならびに変調方法
RU2218075C2 (ru) * 2001-01-09 2003-12-10 Наумов Валерий Аркадьевич Способ регистрации и обработки плетизмограммы для измерения параметров сердечно-сосудистой системы человека и устройство для его осуществления
DE60125326T2 (de) * 2001-05-03 2007-09-27 Ge Healthcare Finland Oy Pulsoximeter
US6825619B2 (en) * 2002-08-08 2004-11-30 Datex-Ohmeda, Inc. Feedback-controlled LED switching
US7194292B2 (en) * 2004-02-25 2007-03-20 General Electric Company Simultaneous signal attenuation measurements utilizing frequency orthogonal random codes
CN100489558C (zh) * 2004-06-07 2009-05-20 埃克森美孚上游研究公司 用于求解隐式储层仿真矩阵的方法

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20020136264A1 (en) * 2001-03-20 2002-09-26 Herleikson Earl C. Spread spectrum measurement device

Also Published As

Publication number Publication date
WO2007104390A3 (fr) 2008-08-28
US20100292593A1 (en) 2010-11-18
DE102006022120A1 (de) 2007-09-06
WO2007104390A2 (fr) 2007-09-20
US8398557B2 (en) 2013-03-19

Similar Documents

Publication Publication Date Title
WO2007096054A2 (fr) Filtrage adaptif permettant une détermination plus fiable des paramètres vitaux
DE102006022056A1 (de) Spektralanalyse zur zuverlässigeren Bestimmung von Vitalparametern
DE19537646C2 (de) Verfahren und Vorrichtung zum Erkennen verfälschter Meßwerte in der Pulsoximetrie zur Messung der Sauerstoffsättigung
DE69307912T2 (de) Verfahren und vorrichtung zur reduzierung von umgebungsgeraeusch in elektronischen ueberwachungsinstrumenten
DE68925988T2 (de) Verfahren und Gerät zur Kompensation von Verzerrungen in einem Pulsoximeter
DE69704264T2 (de) Verfahren und Vorrichtung zur nichtinvasiven Bestimmung der Konzentration einer Komponente
DE69410294T2 (de) Medizinischer sensor mit amplitudenunabhängigem ausgangssignal
DE68926405T2 (de) Verbessertes Verfahren und Gerät zur Messung optischer Impulse
DE69829621T2 (de) Verfahren und Gerät zur Unterdrückung von Artefakten in physiologischen Signalen
EP1859730B1 (fr) Capteur destiné à mesurer des signes vitaux d'un être vivant
DE69729316T2 (de) Vorrichtung zur messung der blutströmung in mikrogefässen
DE69604464T2 (de) Medizinisches Überwachungsgerät, insbesondere Puls-Oximeter
DE60133533T2 (de) Verfahren und vorrichtung zur erfassung eines physiologischen parameters
CA2172329C (fr) Methode et systeme d'analyse par electromyographie a diaphragme
DE60126812T2 (de) Verfahren und gerät zur abschätzung eines physiologischen parameters von einem physiologischen signal
CN108158573A (zh) 基于自适应阈值小波变换的心电信号降噪方法
DE112019002467T5 (de) System und verfahren für die fernmessungen von vitalzeichen
DE2846530A1 (de) Elektronischer blutdruckmesser (sphygmomanometer)
EP1987444A2 (fr) Procédé d'étalement de spectre pour déterminer des paramètres vitaux
CN106889981B (zh) 一种用于提取胎儿心率的智能终端
DE102007001709A1 (de) Verfahren und Messgerät zur Bestimmung der Atemfrequenz
DE69725622T2 (de) Verfahren für das harmonische filtern von daten
DE4238641C2 (de) Vorrichtung und Arbeitsverfahren zum Bestimmen und Auswerten des physiologischen Zustandes von Gefäßsystemen
DE102008022920A1 (de) Vorrichtung zur Erkennung von Leblosigkeit
EP3399914A2 (fr) Dispositif et procédé de détermination continue et non-invasive de paramètres physiologiques d'un sujet

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 20080814

AK Designated contracting states

Kind code of ref document: A2

Designated state(s): AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IS IT LI LT LU LV MC NL PL PT RO SE SI SK TR

AX Request for extension of the european patent

Extension state: AL BA HR MK RS

DAX Request for extension of the european patent (deleted)
RBV Designated contracting states (corrected)

Designated state(s): DE ES FR GB

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: EXAMINATION IS IN PROGRESS

17Q First examination report despatched

Effective date: 20170103

GRAJ Information related to disapproval of communication of intention to grant by the applicant or resumption of examination proceedings by the epo deleted

Free format text: ORIGINAL CODE: EPIDOSDIGR1

GRAP Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOSNIGR1

RIC1 Information provided on ipc code assigned before grant

Ipc: A61B 5/024 20060101AFI20170502BHEP

GRAP Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOSNIGR1

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: GRANT OF PATENT IS INTENDED

INTG Intention to grant announced

Effective date: 20170623

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 20171104