JP2005329149A - Method and instrument for respiratory information measurement - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an instrument for respiratory information measurement, which finds respiratory information such as a respiratory rate and a respiratory pattern of a subject by just analyzing measured pulse waves. <P>SOLUTION: This respiratory information measuring method for obtaining the respiratory information, extracts a baseline fluctuation voltage waveform indicating a transition (the baseline fluctuation) of the minimum voltage in a period of a single beat of the pulse wave from the measured pulse waves. The respiratory pattern of the subject is found by using the fact that the fluctuation pattern of the baseline fluctuation voltage waveform synchronizes with the respiratory pattern. The respiratory rate of the subject is found by counting the number of times where the baseline fluctuation voltage waveform exceeds a predetermined threshold. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a respiratory information measurement method and apparatus for determining respiratory information such as a subject's respiratory rate and respiratory pattern by analyzing a measured pulse wave.

  Conventionally, in order to measure biological information (vital sign) such as pulse rate, blood glucose level, blood oxygen saturation, breathing pattern, etc. for health management and diagnostic purposes, a dedicated sensor and measurement for each purpose Equipment was needed. For example, in order to measure blood oxygen saturation, it is necessary to fix a sensor on the fingertip, and in order to measure a breathing pattern, an elastic belt with a built-in sensor is wrapped around the chest, or in the vicinity of the chest or nose. It was necessary to attach an airflow sensor, an electrode, or the like. For this reason, it is difficult to say that it is necessary to restrain the subject for a certain period of time for measurement, and it is difficult to say that these measurement devices are used daily unless there is a need to measure vital signs from a clinical standpoint. Was never used.

  However, in recent years, the population of society has been aging, and the modernization of lifestyle habits has increased the potential risk of lifestyle-related diseases. Therefore, there has been a demand for means for measuring comfortably at a higher frequency.

  From such a background, the following Patent Document 1 discloses that the pulse rate is unconstrained and unconscious while the subject is in a normal life, instead of the conventional measuring device only for the measurement of vital signs. Biological information measuring devices that measure vital signs such as blood glucose levels have been proposed.

  FIG. 9 shows a front view of a sensor element used in this biological information measuring apparatus, and FIG. 10 shows a state in which the sensor element is attached to a subject. As shown in FIG. 9, the sensor element 100 has an ear receiver shape, and detects a light that passes through the subject out of the light emitted from the light emitting unit 101 and the light emitted from the light emitting unit 101. A light receiving unit 102 and a speaker 103 for reproducing music and the like are arranged. As shown in FIG. 10, the sensor element 100 is used by being fixed to the concha cavity of the subject as in the case of a general ear receiver, whereby the light emitting unit 101 and the light receiving unit 102 are peripheral to the opening of the ear canal. Abut. Here, since the blood flow has a pulse, and the permeability of blood is lower than that of other biological parts such as skin, the intensity of the reflected light detected by the light receiving unit 102 is synchronized with the pulse. Fluctuate. Therefore, the pulse rate can be obtained by continuously measuring this variation. Moreover, a blood glucose level and a blood cholesterol level are measurable by projecting the light of the wavelength which is easy to be absorbed by the blood components (glucose, cholesterol, etc.) to measure.

Japanese Patent Laid-Open No. 11-178803

  By the way, in the biological information measuring device described in Patent Document 1 described above, vital signs such as a pulse rate, a blood glucose level, and a blood cholesterol level can be measured by analyzing a pulse wave, but the respiratory rate and the breathing pattern, etc. Since breathing information cannot be measured, when measuring breathing information, wrap an elastic belt with a built-in sensor around the chest as described above, or attach an airflow sensor or electrode near the chest or nose. It was necessary to do. On the other hand, if respiratory information can be obtained by analyzing the pulse wave, more vital signs can be measured in parallel while minimizing the burden on the subject. Above, it is considered very useful.

  The present invention has been proposed in view of such a conventional situation, and provides a respiratory information measurement method and apparatus for obtaining respiratory information such as a subject's respiratory rate and respiratory pattern only by analyzing a measured pulse wave. The purpose is to do.

  In order to achieve the above-described object, the present inventors have conducted intensive research from various viewpoints. As a result, it was found that the waveform pattern of the baseline fluctuation voltage, which is the transition of the lowest voltage during the period of one pulse wave, shows a significant correlation with the respiratory pattern. The present invention has been completed based on such findings.

  That is, the respiratory information measurement method according to the present invention includes a pulse wave detection step for detecting a pulse wave generated by blood circulation and a baseline fluctuation component extraction for extracting a baseline fluctuation component of the pulse wave detected in the pulse wave detection step. And a respiration information calculation step of calculating respiration information based on the time variation pattern of the baseline variation component extracted in the baseline variation component extraction step.

  The respiratory information measuring apparatus according to the present invention includes a pulse wave detection unit that detects a pulse wave generated by blood circulation, and a baseline fluctuation component extraction unit that extracts a baseline fluctuation component of the pulse wave detected by the pulse wave detection unit. And respiration information calculating means for calculating respiration information based on the time fluctuation pattern of the baseline fluctuation component extracted by the baseline fluctuation component extraction means.

  Here, when detecting a pulse wave, light is projected from the light emitting unit to a part for detecting the pulse wave, and transmitted light or reflected light obtained from this part is detected by the light receiving unit.

  In the respiratory information measuring method and apparatus therefor according to the present invention, since the subject's respiratory information is obtained based on the fluctuation pattern of the baseline fluctuation voltage waveform, which is the transition of the lowest voltage in the period of one pulse of the pulse wave generated by blood circulation, Respiratory information can be obtained simply by measuring waves.

  Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings. In this embodiment, the present invention is applied to a respiratory information measuring method and apparatus for obtaining respiratory information such as a subject's respiratory rate and respiratory pattern by analyzing a pulse wave. In the following, a method for obtaining respiratory information from a pulse wave will be described first, and then an example of a respiratory information measuring device that performs processing for measuring a pulse wave and analyzing it to obtain respiratory information will be described.

  A volume pulse wave is obtained by electrically and mechanically capturing the expansion / contraction of skin blood vessels (peripheral blood vessels) from the skin surface. FIG. 1 (A) shows a waveform after a component having a frequency higher than about 20 Hz is removed by a low-pass filter from the detected volume pulse wave and amplified. The full width of the graph shown in FIG. 1A is about 2 seconds. In the figure, t represents a time interval corresponding to one pulse wave. In addition, a baseline fluctuation voltage waveform representing the transition of the minimum voltage (baseline fluctuation) in the period of one pulse wave is shown by a thick line in FIG. The full width of the graph shown in FIG. 1 is approximately 30 seconds. In the figure, T indicates a time interval corresponding to one cycle of the baseline fluctuation voltage waveform. As can be seen by comparing t and T in FIGS. 1A and 1B, the baseline fluctuation voltage waveform is accompanied by time fluctuation having a longer period than the pulse wave.

  FIG. 2 shows the baseline fluctuation voltage waveform (solid line in the figure) superimposed on a respiration pattern (broken line in the figure) confirmed by another method. In FIG. 2, the upper part of the breath pattern graph shows an inhaled state, and the lower part of the graph shows an exhausted state. From FIG. 2, it can be confirmed that the fluctuation pattern of the baseline fluctuation voltage waveform is synchronized with the breathing pattern. As long as there is no disturbance such as the body movement of the subject himself, it is estimated that the fluctuation pattern of the baseline fluctuation voltage waveform is induced by respiration. This phenomenon is due to the fact that the heart and aorta in the thoracic cavity are affected by changes in pressure in the thoracic cavity due to respiration, and those factors that are added to the blood ejection pressure of the heart are detected at the periphery. I can explain.

  The respiration information measurement method in the present embodiment obtains respiration information based on such a fluctuation pattern of the baseline fluctuation voltage waveform. In other words, the breathing pattern of the subject can be obtained by measuring the fluctuation pattern of the baseline fluctuation voltage waveform, and the breathing rate of the subject can be obtained by counting the number of times the baseline fluctuation voltage waveform exceeds a predetermined threshold. Can do. Furthermore, by observing the temporal fluctuation of the respiratory rate, it can be applied to the estimation of the momentum and stress governing the respiration or the sleep apnea syndrome. In particular, in this respiration information measurement method, since respiration information can be obtained only from the fluctuation pattern of the baseline fluctuation voltage waveform, it is only necessary to measure one system of pulse wave data in any part of the living body of the subject. Convenient.

  Next, an example of a respiratory information measuring device that measures a pulse wave and analyzes it to obtain respiratory information as described above will be described.

  FIG. 3 shows an outline of the respiratory information measuring device in the present embodiment. As shown in FIG. 3, the respiratory information measuring apparatus 1 according to the present embodiment reproduces music and the like while measuring the sensor element 10 in the form of an inner ear type ear receiver for measuring a pulse wave, and is measured by the sensor element 10. A signal analyzing unit 30 for analyzing the pulse wave and obtaining respiratory information is connected via the wiring 50. The signal analysis unit 30 is provided with a display unit 31, and the respiration information analyzed by the signal analysis unit 30 is provided to the subject through the display unit 31.

  FIG. 4 shows an enlarged view of the sensor element 10 in the respiratory information measuring apparatus 1. As shown in FIG. 4, the sensor element 10 includes a main body 20 having a speaker 21 for outputting music and the like reproduced by the signal analysis unit 30, and a flexible cushioning material such as silicon rubber and low-rebound urethane. As shown in FIG. 5, when measuring blood pressure, the earpiece 22 is inserted into the ear canal and the main body 20 is placed in the concha of the subject as shown in FIG. Used to be fixed to the cavity.

  An example of a side sectional view of the earpiece 22 is shown in FIGS. A through hole is provided in the center of the earpiece 22, and sound waves output from the speaker 21 are sent to the ear canal through the through hole and reach the eardrum. Further, the earpiece 22 is embedded with a light emitting unit 23 and a light receiving unit 24 for measuring a pulse wave, and the light emitting unit 23 and the light receiving unit 24 are provided with the sensor element 10 as a subject as shown in FIG. It is disposed so that the optical axis of the projection light projected from the light emitting unit 23 and the reflected light thereof is at right angles or close to right angles with the ear canal when it is worn and in contact with the skin inside the ear canal. In FIG. 6, only one light receiving unit 24 is provided. However, by providing a plurality of light receiving units 24, reflected light passing through different paths can be received, and the pulse wave can be measured with higher accuracy.

  In the earpiece 22, a light emitting element such as a small LED (Light Emission Diode) element can be used for the light emitting unit 23. For the light receiving unit 24, for example, a photodetector using a photodiode or pyroelectric microsensor using Si, InGaAs, Ge or the like can be used. The light emitting unit 23 projects red light and near infrared light toward the outside of the earpiece 22, that is, the surface in contact with the skin of the ear canal. The projected light passes through the subject and partly reflects and diffuses back. The light receiving unit 24 receives the reflected light, converts it into an electrical signal, and transmits it to the signal analyzing unit 30 via the wiring 50. Here, the blood flow has a pulse, and the blood permeability is lower than that of other biological parts such as the skin. Therefore, the intensity of the reflected light detected by the light receiving unit 24 is synchronized with the pulse. Fluctuate. Therefore, a pulse wave can be obtained by continuously measuring this variation.

  In the respiratory information measuring apparatus 1 according to the present embodiment, since the light emitting unit 23 and the light receiving unit 24 are embedded in the earpiece 22 made of a flexible cushioning material, the light emitting unit 23 and the light receiving unit 24 are made of cushioning material. The repulsive force makes contact with the inner surface of the ear canal with an appropriate pressure. Thereby, it can suppress effectively that the distance from the light emission part 23 and the light-receiving part 24 to skin by the influence of test subject's own movement and gravity can be suppressed, and the stable measurement is attained. Further, since the earpiece 22 is inserted into the ear canal and is not exposed outside the body, there is an advantage that the earpiece 22 is not easily affected by external light during measurement. In addition, since the inside of the external auditory canal is far from muscles that can be moved arbitrarily such as arms and fingers, there is an advantage that there is little influence of the subject's own movement and there is no need to restrain the subject during measurement.

  Furthermore, in the respiratory information measuring apparatus 1 according to the present embodiment, the sensor element 10 has an inner-ear type ear receiver shape, and music and the like can be output via the speaker 21 of the main body unit 20. Respiratory information can be measured in a relaxed state unconsciously and unconsciously while listening to music or the like. For this reason, it can be worn for a long time, and it is also possible to observe trends in respiratory information such as transition and fluctuation. In particular, since the light emitting unit 23 and the light receiving unit 24 embedded in the earpiece 22 are small in size, a decrease in acoustic performance can be minimized, and the design as an ear receiver is not impaired. Further, in the respiratory information measuring apparatus 1 according to the present embodiment, the main body unit 20 having the speaker 21 and the earpiece 22 having the light emitting unit 23 and the light receiving unit 24 are separated. Even when measured, it is hardly affected by acoustic vibration.

  FIG. 8 shows a schematic configuration of a part related to measurement of respiratory information in the respiratory information measuring apparatus 1 described above. The electrical signal transmitted from the light receiving unit 24 of the earpiece 22 is first input to the preamplifier unit 40 of the signal analysis unit 30. The preamplifier unit 40 is induced by noise that is electromagnetically induced from a power supply frequency or light from a lighting fixture by removing a component having a frequency higher than about 20 Hz from the input electric signal by a low-pass filter. Remove noise. Further, the preamplifier unit 40 amplifies the electric signal from which this noise has been removed. The signal processing circuit 41 separates the baseline fluctuation component from the electrical signal.

  The separated baseline fluctuation component is integrated with a long time constant of about 5 to 10 seconds in the feedback circuit 42 and supplied to the light emitting unit driving circuit 43. The light emitting unit drive circuit 43 conversely detects the pulse wave detected by the light receiving unit 24 so as to increase the light emission amount of the light emitting unit 23 to obtain a larger change when the pulse wave voltage detected by the light receiving unit 24 is small. When the voltage is large, the light emission amount of the light emitting unit 23 is decreased to control the light receiving unit 24 and the subsequent signal processing circuit from being saturated.

  The separated baseline fluctuation component is quantized by an analog / digital (A / D) converter 44 and sent to the processor 45 as numerical data. The processor 45 analyzes the data as described above to obtain the breathing information of the subject, records the result in the storage medium 46, and displays the result on the display unit 31 by characters or other methods.

  In addition, in the light emission part 23 and the light-receiving part 24 mentioned above, a blood glucose level and a blood cholesterol level can also be measured by projecting the light of the wavelength which is easy to be absorbed by the blood component (glucose, cholesterol, etc.) to measure. . Further, the oxygen saturation level in blood can be measured by utilizing the difference in light absorption rate between hemoglobin to which oxygen is bound and hemoglobin to which oxygen is not bound. Thus, according to the respiratory information measuring apparatus 1 in the present embodiment, in addition to blood pressure, a plurality of biological information such as pulse rate, blood sugar level, blood cholesterol value, blood oxygen saturation, etc. are measured in parallel. This is beneficial for the health management of the subject. Further, higher-order analysis such as analysis of the correlation between the respective pieces of biological information is possible.

  Although specific embodiments to which the present invention is applied have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention. Of course there is.

  For example, in the above-described embodiment, the sensor element having the inner ear type ear receiver shape as shown in FIG. 3 is used in the blood pressure measuring device. However, the present invention is not limited to this shape, and is not limited to this shape. The shape may be such that the peripheral tissue of the human body is sandwiched between them. Even in this case, it is possible to measure the pulse wave by projecting light from the light emitting unit to the peripheral tissue and detecting the transmitted light or reflected light by the light receiving unit, and analyzing the pulse wave Respiratory information can be obtained.

It is a figure explaining a volume pulse wave and its base line fluctuation | variation, The figure (A) shows the waveform of the volume pulse wave after performing noise removal and amplification, The figure (B) is the figure of this volume pulse wave. The baseline fluctuation voltage waveform is shown. It is a figure which superimposes a baseline fluctuation voltage waveform and a respiration pattern. It is the schematic which shows an example of the respiration information measuring device in this Embodiment. It is a perspective view which expands and shows the sensor element used for the respiration information measuring device. It is a figure which shows the state which mounted | wore the test subject with the sensor element. It is a sectional side view which shows the earpiece of the sensor element. It is a figure which shows the state in which the light emission part and light-receiving part of a sensor element are contact | abutted to the skin of a test subject's inner ear canal. It is a figure which shows schematic structure of the part relevant to the measurement of respiration information among the respiration information measuring devices. It is a perspective view which expands and shows the sensor element used for the conventional biological information measuring device. It is a figure which shows the state which mounted | wore the test subject with the sensor element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Respiration information measuring device, 10 Sensor element, 20 Main body part, 21 Speaker, 22 Earpiece, 23 Light emission part, 24 Light reception part, 30 Signal analysis part, 31 Display part, 40 Preamplifier part, 41 Signal processing circuit, 42 Feedback circuit, 43 Light Emitting Unit Drive Circuit, 44 A / D Converter, 45 Processor, 46 Storage Medium

Claims (9)

A pulse wave detection step for detecting a pulse wave generated by blood circulation;
A baseline fluctuation component extraction step for extracting a baseline fluctuation component of the pulse wave detected in the pulse wave detection step;
A respiration information calculating step of calculating respiration information based on the time variation pattern of the baseline variation component extracted in the baseline variation component extraction step.   2. The respiratory information measuring method according to claim 1, wherein in the respiratory information calculation step, the respiratory rate is calculated based on the number of times that the baseline fluctuation component exceeds a predetermined threshold during a predetermined period. A noise removal step of removing high-frequency noise of the pulse wave detected in the pulse wave detection step;
The respiratory information measurement method according to claim 1, wherein, in the baseline fluctuation component extraction step, a baseline fluctuation component is extracted from the waveform from which noise has been removed in the noise removal step.   In the pulse wave detection step, the pulse wave is detected by projecting light from the light emitting unit to a part for detecting the pulse wave, and detecting transmitted light or reflected light obtained from the part by the light receiving unit. The respiratory information measuring method according to claim 1. Pulse wave detection means for detecting a pulse wave generated by blood circulation;
Baseline fluctuation component extraction means for extracting the baseline fluctuation component of the pulse wave detected by the pulse wave detection means;
A respiration information measuring device comprising: respiration information calculating means for calculating respiration information based on the time fluctuation pattern of the baseline fluctuation component extracted by the baseline fluctuation component extraction means.   6. The respiratory information measuring apparatus according to claim 5, wherein the respiratory information calculating means calculates a respiratory rate based on the number of times that the baseline fluctuation component exceeds a predetermined threshold during a predetermined period. Noise removing means for removing high-frequency noise of the pulse wave detected by the pulse wave detecting means,
The respiratory information measuring apparatus according to claim 5, wherein the baseline fluctuation component extraction unit extracts a baseline fluctuation component from the waveform from which noise has been removed by the noise removal unit.   6. The pulse wave detecting means includes: a light emitting unit that irradiates light to a part that detects a pulse wave; and a light receiving part that detects transmitted light or reflected light obtained from the part. The respiratory information measuring device described.   9. The respiratory information measuring apparatus according to claim 8, wherein the pulse wave detecting means has a shape in which the light emitting part and the light receiving part are fixed in contact with the inner surface of the ear canal of the subject.

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