This invention relates to a swallowing movement monitoring sensor which measures swallowing movement of a subject.
In the aging society in recent years, elderly people live a longer life whereas they suffer from various physical influences by deterioration in functions of the whole body involved with aging. Dysphagia represents one of such influences. Dysphagia refers to impairment of a swallowing function which is an action to swallow food and/or drinks.
Endoscopic swallowing examination, videofluoroscopic examination of swallowing, and swallowing pressure examination have conventionally widely been used as methods of assessing a swallowing function. A repetitive saliva swallowing test, a modified water swallowing test, and a food test have been conducted as screening of the dysphagia.
Recently, cervical auscultation of swallowing sound and assessment with a saturation monitor have also been attempted (see NPDs 1 and 2).
The endoscopic swallowing examination, the videofluoroscopic examination of swallowing, and the swallowing pressure examination above allow objective assessment of the swallowing function, whereas they require expensive equipment and staff and rely on an invasive test.
In the repetitive saliva swallowing test, the modified water swallowing test, and the food test, swallowing is sensed normally based on visual recognition and palpation of laryngeal elevation. Therefore, though those tests are more simplified than the examination above, they are disadvantageously low in accuracy and objectivity, and in particular, they are low in sensitivity to minor dysphagia.
Cervical auscultation of swallowing sound is a non-invasive test method, however, it may be difficult to distinguish swallowing sound from mastication sound, sound in the mouth, and sound of laryngeal elevation irrelevant to swallowing. It is difficult to detect minor aspiration. Therefore, this method remains as auxiliary diagnosis. Though assessment with the saturation monitor is also non-invasive and simple, relation between variation in saturation and aspiration is yet to be studied and this assessment method thus lacks reliability.
An object of one manner of the present invention is to provide a swallowing movement monitoring sensor which can non-invasively and objectively measure swallowing movement with high sensitivity with a simplified configuration.
A swallowing movement monitoring sensor according to one manner of the present invention is a sensor which measures swallowing movement of a subject. The swallowing movement monitoring sensor includes a first outside shape variation sensor attached to a laryngeal portion of the subject. The first outside shape variation sensor is configured to detect variation in outside shape of the laryngeal portion associated with swallowing movement.
According to the above, a swallowing movement monitoring sensor which can non-invasively and objectively measure swallowing movement with high sensitivity with a simplified configuration can be provided.
Embodiments of the present invention will initially be listed and described.
(1) A swallowing movement monitoring sensor 1 (see
(2) In swallowing movement monitoring sensor 1 according to (1), preferably, the first outside shape variation sensor (outside shape variation sensor 5) includes an optical fiber sheet 10 (see
(3) In swallowing movement monitoring sensor 1 according to (2), preferably, optical fiber 14 (see
By doing so, a length of an optical fiber (an optical path length) can be increased and an interval between adjacent linear portions 14a can be shorter. Consequently, variation in transmission loss in response to movement of the laryngeal portion of a subject is great and hence sensitivity as the swallowing movement monitoring sensor can be improved.
(4) In the swallowing movement monitoring sensor according to (3), preferably, the optical fiber portion is deformed such that a plurality of annular portions 14c (see
By doing so, a contact point where optical fibers are in contact with each other is formed in a portion where annular portions 14c intersect with each other and a portion where annular portion 14c and linear portion 14a intersect with each other. Since a lateral pressure is produced in optical fiber 14 with this contact point serving as a point of load, a higher lateral pressure resulting from movement of the laryngeal portion is applied to optical fiber 14. Consequently, greater variation in quantity of light is caused in response also to slight movement of the laryngeal portion and hence sensitivity as the swallowing movement monitoring sensor can be improved.
(5) In the swallowing movement monitoring sensor according to (3) or (4), preferably, an optical fiber sheet 10C (see
By doing so, in each of the plurality of optical fibers 14 placed on common sheet-like member 12, a transmission loss is varied with application of a lateral pressure in accordance with movement of the laryngeal portion. There is a time lag in variation in transmission loss among the plurality of optical fibers 14. By detecting a time lag of difference in transmission loss, a speed of elevation movement (swallowing movement) of the laryngeal portion of a subject can be measured.
(6) In swallowing movement monitoring sensor 1 according to any of (3) to (5), preferably, optical fiber 14 is a plastic optical fiber, a quartz-based optical fiber, or a plastic clad quartz glass core optical fiber. By doing so, a loss can be produced in transmission light by a lateral pressure applied to the optical fiber from the laryngeal portion. The optical fiber is more preferably a graded index type quartz-based optical fiber.
(7) In the swallowing movement monitoring sensor according to (6), preferably, optical fiber 14 is of a step index type, a graded index type, or a single mode type.
(8) In the swallowing movement monitoring sensor according to any of (3) to (7), preferably, optical fiber sheets 10 and 10A to 10D have a width in the first direction not smaller than 30 mm and not greater than 500 mm and a width in a second direction perpendicular to the first direction not smaller than 30 mm and not greater than 150 mm. The first direction is preferably a direction perpendicular to movement of the laryngeal portion and the second direction is preferably a direction in parallel to movement of the laryngeal portion. Then, regardless of the sex and an individual difference in length of a cervical portion of a subject, variation in outside shape of the laryngeal portion involved with swallowing movement can be measured with high sensitivity.
(9) In swallowing movement monitoring sensor 1 according to (8), preferably, optical fiber sheet 10 (see
(10) In the swallowing movement monitoring sensor according to (8), preferably, optical fiber sheet 10 (see
(11) In the swallowing movement monitoring sensor according to (8), preferably, optical fiber sheet 10 is attached around a neck, with the laryngeal portion being defined as a center, with an annular net made of a stretchable material. By doing so, optical fiber sheet 10 can be in intimate contact with the laryngeal portion and hence variation in outside shape of the laryngeal portion can be measured with high sensitivity.
(12) In the swallowing movement monitoring sensor according to (1), preferably, first outside shape variation sensor 5 (see
(13) In the swallowing movement monitoring sensor according to (1), preferably, first outside shape variation sensor 5 (see
(14) Swallowing movement monitoring sensor 1 according to any of (1) to (13) preferably further includes a microphone 20 attached in an ear of the subject. Microphone 20 is configured to detect swallowing sound produced in the ear in association with swallowing movement. By doing so, variation in outside shape of the laryngeal portion involved with swallowing movement and swallowing sound can simultaneously be captured with a simplified configuration. Therefore, swallowing movement can non-invasively and objectively be measured with high sensitivity.
(15) In the swallowing movement monitoring sensor according to (14), preferably, microphone 20 is implemented by a lavaliere condenser microphone having a diameter not smaller than 1.5 mm and not greater than 5.0 mm. By doing so, swallowing sound can be picked up with high sensitivity.
(16) In the swallowing movement monitoring sensor according to (14) or (15), preferably, swallowing movement monitoring sensor 1 further includes a signal processing unit 30 configured to process a detection signal output from each of the first outside shape variation sensor (outside shape variation sensor 5) and microphone 20.
By doing so, a swallowing function can objectively be assessed by analyzing results of measurement of variation in outside shape of the laryngeal portion involved with swallowing movement and swallowing sound. Therefore, by measuring swallowing movement of a normal example and a dysphagia example with the swallowing movement monitoring sensor system, an objective indicator in dysphagia screening can be presented. Consequently, convenience in clinical use can be enhanced.
(17) In swallowing movement monitoring sensor 1 according to (16), preferably, signal processing unit 30 (see
(18) In swallowing movement monitoring sensor 1 according to (17), preferably, the display (digital oscilloscope 70 and PC 80) shows the output waveform obtained by subjecting the detection signal from the first outside shape variation sensor (outside shape variation sensor 5) to simple moving average processing. By doing so, since noise superimposed on the detection signal can be removed, swallowing movement can be measured with high sensitivity.
(19) In swallowing movement monitoring sensor 1 according to (17) or (18), preferably, signal processing unit 30 (see
When a digital oscilloscope is not used, signal processing unit 30 inputs the detection signal from the first outside shape variation sensor (outside shape variation sensor 5) on which a dummy signal representing an alternating-current signal is superimposed by an audio mixer 62 to a first audio input of an audio input portion of the display (PC 80). The dummy signal has a frequency handleable by an audio amplifier. Signal processing unit 30 further inputs the detection signal from microphone 20 to a second audio input of the audio input portion of the display (PC 80). Thus, output waveforms obtained by subjecting these two signals to digital sampling are shown on the display (PC 80) as being aligned on the identical time axis. By doing so, two output waveforms can be compared with each other by combining simplified apparatuses and hence swallowing movement can readily be detected and analyzed. When the display (PC 80) includes no audio input portion, the same function can be achieved by an external audio input unit.
(20) A swallowing movement monitoring sensor 1A (see
By doing so, in addition to variation in outside shape of the laryngeal portion involved with swallowing movement and swallowing sound of a subject, variation in outside shape of the chest involved with swallowing movement can simultaneously and non-invasively be captured with a simplified configuration. Thus, swallowing movement and a respiration pattern in swallowing can non-invasively and objectively be measured. Consequently, the swallowing function can objectively be assessed.
(21) In swallowing movement monitoring sensor 1A (see
An embodiment of the present invention will be described hereinafter with reference to the drawings. In the drawings below, the same or corresponding elements have the same reference characters allotted and description thereof will not be repeated.
<Configuration of Swallowing Movement Monitoring Sensor>
Referring to
Outside shape variation sensor 5 is attached to a laryngeal portion of a subject. Outside shape variation sensor 5 is configured to detect variation in outside shape of the laryngeal portion associated with swallowing movement. Details of outside shape variation sensor 5 will be described later.
Microphone 20 is a small-sized microphone which has a diameter approximately from 1.5 to 5.0 mm. For example, a lavaliere condenser microphone can be employed for microphone 20.
Signal processing unit 30 processes a detection signal output from each of outside shape variation sensor 5 and microphone 20. Details of signal processing unit 30 will be described later.
As shown in
Microphone 20 is attached to the inside of an ear 114 (in an external auditory meatus 116) of subject 100. Microphone 20 is configured to detect swallowing sound produced in the ear in association with swallowing movement.
A detection signal indicative of variation in outside shape of laryngeal portion 108 detected by outside shape variation sensor 5 and a detection signal indicative of swallowing sound detected by microphone 20 are both input to signal processing unit 30 (
The present inventors have found that swallowing sound characterized by bimodal sounds of clicking sound containing a high-frequency component and a sound group containing a large amount of subsequent low-frequency components is produced in association with instantaneous opening of an auditory tube at the time of swallowing. The present inventors have further succeeded in recording swallowing sound from the inside of the ear (see, for example, NPD 2).
The output waveform in
As shown in
With swallowing movement monitoring sensor 1 according to the present embodiment, swallowing sound is recorded from the inside of an ear and simultaneously variation in outside shape of the laryngeal portion associated with swallowing movement is detected. Swallowing movement can thus accurately be measured with a non-invasive and objective measurement method.
(Configuration of Optical Fiber Sheet)
Referring to
Optical fiber 14 is partially fixed to sheet-like member 12, for example, with a double-faced tape. A material for sheet-like member 12 is not particularly limited so long as it can support optical fiber 14. Optical fiber 14 is not only placed on sheet-like member 12 but also can be embedded in sheet-like member 12.
Sheet-like member 12 has a length in a direction of width (a left-right direction in the figure) not smaller than 30 mm and not greater than 500 mm and a length in a direction of length (an up-down direction in the figure) not smaller than 30 mm and not greater than 150 mm. Then, regardless of the sex or an individual difference in length of the cervical portion of subjects, variation in outside shape of the laryngeal portion involved with swallowing movement can be measured with high sensitivity.
Optical fiber 14 is an optical transmission medium which includes a core, an outer layer on an outer side of the core which is called a clad, and a cover layer which covers the outer layer. A plastic optical fiber, a quartz-based optical fiber, or a plastic clad quartz glass core optical fiber can be employed for optical fiber 14. The plastic optical fiber is an optical fiber in which acrylic is employed for a core material and a fluorine resin is employed for a cladding material. The quartz-based optical fiber is an optical fiber in which quartz glass is employed for a core material and a cladding material. The plastic clad quartz glass core optical fiber is an optical fiber in which quartz glass is employed for a core material and a resin is employed for a cladding material.
A constant quantity of light continuously supplied from a not-shown light source portion is incident on an input end 14i of optical fiber 14. Light incident on input end 14i of optical fiber 14 is transmitted through optical fiber 14 and thereafter emitted from an output end 14o of optical fiber 14. A not-shown optical power meter (light reception portion) is connected to output end 14o of optical fiber 14. The optical power meter measures a quantity of light emitted from optical fiber 14.
As shown in
In optical fiber 14, since a microbending loss is caused due to stress imposed by the lateral pressure, an excessive loss is caused in a transmission loss of optical fiber 14. Optical fiber sheet 10 according to the present embodiment makes use of this characteristic, and swallowing movement of subject 100 can be measured by measuring variation in transmission loss due to variation in lateral pressure applied to optical fiber 14 resulting from swallowing movement.
Referring to
In the example in
The plurality of linear portions 14a are arranged as being aligned at an interval in the direction of length (the up-down direction in the figure) of sheet-like member 12. The direction of length of sheet-like member 12 corresponds to the “second direction.” The second direction is set, for example, to a direction in parallel to movement of the laryngeal portion (the direction shown with the arrow in
As set forth above, optical fiber sheet 10 according to the present embodiment makes use of variation in transmission loss caused by a lateral pressure and hence a longer optical path is more advantageous for improvement in sensitivity. According to the exemplary placement shown in
Specifically, optical fiber sheet 10 was constructed by placing a plastic optical fiber in accordance with the exemplary placement in
The ordinate in
(Swallowing Movement Monitoring Sensor System)
A method of measuring swallowing movement with a swallowing movement monitoring sensor system including swallowing movement monitoring sensor 1 according to the present embodiment and a result of measurement will be described below.
<Configuration of Swallowing Movement Monitoring Sensor System>
Referring to
As described with reference to
Light source portion 40 continuously outputs a constant quantity of light. A light emitting diode (LED) is suitably employed for light source portion 40 because it can supply emission light in a stable manner, it is small in size and light in weight, and it is low in amount of heat generation and power consumption.
Optical power meter 50 receives emission light transmitted from optical fiber 14 and measures a quantity of received light. The measured quantity of received light (an amount of attenuation) is varied with a lateral pressure applied to optical fiber sheet 10 in accordance with movement of the laryngeal portion of the subject. Therefore, it can be determined that movement of the laryngeal portion is great when variation in quantity of received light is great and movement of the laryngeal portion is small when variation in quantity of received light is low. Optical power meter 50 converts the measured quantity of received light into an electric signal and inputs the resultant electric signal to a channel CH1 of digital oscilloscope 70.
A detection signal indicating swallowing sound detected by microphone 20 is input to audio mixer 60. Audio mixer 60 adjusts a volume of the detected swallowing sound and inputs the adjusted detection signal to a channel CH2 of digital oscilloscope 70.
Digital oscilloscope 70 receives an output signal from optical power meter 50 at channel CH1 and receives an output signal from audio mixer 60 at channel CH2. Digital oscilloscope 70 holds variation over time (output waveform) of the output signal from optical power meter 50 and the output signal from audio mixer 60, for example, as voltage waveform data. Digital oscilloscope 70 transmits two output waveforms to PC 80.
Digital oscilloscope 70 can also show two output waveforms as being aligned on the same time axis. Digital oscilloscope 70 corresponds to one embodied example of the “display” configured to be able to show an output waveform of a detection signal from microphone 20 and an output waveform of a detection signal from optical fiber sheet 10 as being aligned on the same time axis.
PC 80 analyzes two pieces of output waveform data transmitted from digital oscilloscope 70 by driving analysis software installed in advance. A result of analysis by PC 80 is shown on a display apparatus (not shown) such as a CRT or a printer. PC 80 corresponds to one embodied example of the “analysis portion.”
<Method of Measurement of Swallowing Movement and Result of Measurement>
Swallowing movement of a subject was measured with swallowing movement monitoring sensor system 200 shown in
(First Result of Measurement)
In measurement, a 22-year old adult male without dysphagia was adopted as a subject and optical fiber sheet 10 was attached to the laryngeal portion of the subject. Optical fiber sheet 10 was constructed such that a plastic optical fiber was placed in accordance with the exemplary placement in
Microphone 20 was attached to the inside of an ear of the subject. A lavaliere condenser microphone (a trade name of Countryman B06 manufactured by Countryman Associates, Inc.) having a diameter of 2.5 mm was employed as microphone 20. The condenser microphone was passed through an ear plug and inserted in the ear of each subject to thereby record swallowing sound. The condenser microphone was connected to audio mixer 60 (a trade name of Mackie 402-VLZ3 manufactured by Mackie)
Drinking water (for example, water) and soft food (for example, jelly) were selected as food and beverage to be swallowed.
In swallowing movement monitoring sensor system 200, red LED light (having a wavelength of 650 nm) from light source portion 40 was incident on the input end of optical fiber 14 and a quantity of light emitted from optical fiber 14 was measured with optical power meter 50.
A detection signal from optical fiber sheet 10 and a detection signal from microphone 20 were input to channels CH1 and CH2 of digital oscilloscope 70 (a trade name of UDS-5202 manufactured by JDS Inc.), respectively. PC 80 determined correspondence between output waveforms of the two detection signals by starting up analysis software which can measure the two detection signals on the same time axis.
In each of
Based on comparison between the output waveforms from optical fiber sheet 10 shown in
(Second Result of Measurement)
In swallowing movement monitoring sensor system 200, digital oscilloscope 70 was changed to a digital oscilloscope (a trade name of OWON VDS3104 manufactured by Lilliput) different from the digital oscilloscope (a trade name of UDS-5202 manufactured by JDS Inc.) used in the first result of measurement. The detection signal from optical fiber sheet 10 and the detection signal from microphone 20 were input to channels CH1 and CH2 of the new digital oscilloscope, respectively.
In measurement, four adult males without dysphagia were adopted as subjects and optical fiber sheet 10 was attached to the laryngeal portion of each subject.
A graded index type quartz-based optical fiber (GI-SiO2) was employed for optical fiber 14 of optical fiber sheet 10. GI-SiO2 is a quartz-based optical fiber having such a graded index that an index of refraction has a distribution in symmetry with respect to a central axis from the center of the core toward the clad.
Drinking water (for example, tea) and soft food (for example, almond jelly) were selected as food and beverage to be swallowed.
Referring to
Three sharp audio waveforms (clicking sounds) in total were observed in the output waveform from microphone 20 at times T1, T2, and T3, and it can be seen that the number of times of swallowing and the number of clicking sounds match with each other.
Decrease in quantity of received light was observed at each of times T1, T2, and T3 when the clicking sounds were observed in the output waveform from optical fiber sheet 10. It can thus be seen that a transmission loss of optical fiber 14 is varied each time the subject swallows saliva.
It was thus confirmed based on comparison between the output waveform from microphone 20 and the output waveform from optical fiber sheet 10 that timings of variation in waveform well match with each other.
The waveform shown in
As described above, swallowing movement monitoring sensor 1 according to the present embodiment is configured such that optical fiber sheet 10 captures movement of the laryngeal portion of the subject whereas microphone 20 captures clicking sound (swallowing sound) emitted at the moment of opening of the auditory tube in the ear. It was confirmed from the results of measurement with swallowing movement monitoring sensor system 200 shown in
(Third Result of Measurement)
In measurement, sensitivity to swallowing of saliva, of three types of optical fiber sheets 10 different in optical fiber included therein was further compared, with four subjects in the second results of measurement being adopted.
In comparison, for swallowing movement monitoring sensor system 200 shown in
Swallowing movement was measured for each subject with three types of optical fiber sheets 10 and microphone 20.
Then, whether the output waveform from optical fiber sheet 10 was varied at the same timing as the output waveform from microphone 20 and magnitude of variation in output waveform from optical fiber sheet 10 were assessed based on the results of measurement.
In assessment, an example in which the output waveform from optical fiber sheet 10 was varied at the same timing as the output waveform from microphone 20 and magnitude of variation was not smaller than a threshold value was determined as “good sensitivity.” An example in which the output waveform from optical fiber sheet 10 was not varied at the timing of variation in output waveform from microphone 20 or magnitude of variation in output waveform from optical fiber sheet 10 was smaller than the threshold value was determined as “poor sensitivity.” Table 1 shows results of comparison. Table 1 shows sensitivity of each optical fiber with a frequency of assessment as “good sensitivity” of the four results of measurement.
Referring to Table 1, when POF was employed, though the output waveform from optical fiber sheet 10 was varied, magnitude of variation smaller than the threshold value was observed. Depending on the subject, the output waveform from optical fiber sheet 10 without variation was observed. Consequently, a frequency of good sensitivity was 25%.
When GI-SiO2 was employed, variation in output waveform from optical fiber sheet 10 was clearly observed in all of the four subjects (frequency of 100%). HSSF exhibited sensitivity intermediate between POF and GI-SiO2 (frequency of 50%). Consequently, it was confirmed that optical fiber sheet 10 including GI-SiO2 was highest in sensitivity to swallowing movement.
A modification of swallowing movement monitoring sensor 1 and swallowing movement monitoring sensor system 200 according to the present embodiment will be described below. Each modification is by way of example and partial substitution or combination of features shown in different modifications can naturally be made.
[First Modification]
Exemplary placement of an optical fiber on an optical fiber sheet will be described in a first modification.
As described with reference to
Specifically, the meandering portion has a plurality of linear portions 14a which extend in the direction of width (the first direction) of rectangular sheet-like member 12 having a lateral width of 85 mm and a vertical width of 65 mm and a plurality of curved portions 14b connecting end portions of two linear portions 14a to each other.
The plurality of linear portions 14a are arranged as being aligned at an interval in the direction of length (the second direction) of sheet-like member 12. In the example in
According to such a configuration, a length of the optical fiber (an optical path length) in optical fiber sheet 10A is longer than in optical fiber sheet 10. With increase in number of linear portions 14a, an interval between adjacent linear portions 14a is shorter. Consequently, optical fiber sheet 10A is greater in variation in transmission loss in response to movement of the laryngeal portion of the subject than optical fiber sheet 10, and hence it can achieve improved sensitivity as the swallowing movement monitoring sensor.
In exemplary placement shown in
The plurality of annular portions 14c are formed as being aligned in the direction of width of sheet-like member 12 in at least one 14a of the plurality of linear portions 14a. Annular portion 14c does not have to be in a shape of a perfect circle but may be collapsed like an ellipse.
Annular portion 14c is arranged to intersect with an adjacent annular portion 14c and to intersect with at least one linear portion 14a. Intersection means that optical fibers intersect with each other in a plan view of sheet-like member 12 and one optical fiber may apply a lateral pressure to the other optical fiber when force is applied in a direction perpendicular to the surface of sheet-like member 12. The optical fiber produces a transmission loss when a lateral pressure is applied thereto. Therefore, a greater number of intersecting portions is preferable.
In the example in
In exemplary placement shown in
Specifically, in optical fiber sheet 10C shown in
In the example in
In optical fiber sheet 10D shown in
In the example in
In the exemplary placement shown in
A lateral pressure in accordance with movement of the laryngeal portion of the subject is applied to the meandering portions of optical fibers 14U and 14D. As the lateral pressure is varied with elevation and descent of the laryngeal portion of the subject, a transmission loss of each of optical fibers 14U and 14D is varied.
In the exemplary placement in
In particular, according to optical fiber sheet 10D shown in
Though
[Second Modification]
In a second modification, a method of attaching an optical fiber sheet will be described. As shown in
As shown in
Swallowing movement of the subject to which optical fiber sheet 10 was attached with fixing band 300 was measured. In measurement, an adult male without dysphagia was adopted as the subject and optical fiber sheet 10 was attached to the laryngeal portion of the subject with the cervical spine fixing instrument.
GI-SiO2 was employed for optical fiber 14 of optical fiber sheet 10.
Referring to
Optical fiber sheet 10 can be attached also with an elastic member in a form of a string as shown in
As shown in
Swallowing movement of the subject to which optical fiber sheet 10 was attached with elastic strings 310 and 320 was measured. The subject is the same as the subject in the results of measurement in
Referring to
When the results of measurement shown in
[Third Modification]
Though the configuration in which detection signals from optical fiber sheet 10 and microphone 20 are measured with digital oscilloscope 70 has been described in the embodiment described above, accurate measurement may become difficult due to superimposition of noise generated in digital oscilloscope 70 on the detection signals.
In a third modification, noise superimposed on the output waveform is removed by subjecting the output waveform measured with digital oscilloscope 70 to simple moving average processing.
[Fourth Modification]
A configuration example of signal processing unit 30 will be described in a fourth modification.
As shown in
In the present modification, representation of waveforms of two output signals different in frequency band on PC 80 instead of digital oscilloscope 70 as being aligned on the same time axis was attempted. Namely, PC 80 corresponds to the “display”. PC 80 contains an audio input portion configured to be capable of digital sampling of a detection signal from microphone 20. When the display includes no audio input portion, the similar function can be achieved by an external audio input unit.
Specifically, initially, with audio analysis software, an output signal from audio mixer 60 was recorded at a plurality of different sampling frequencies and a lower limit of the sampling frequency at which clicking sound (swallowing sound) was clearly obtained was set. In experiments, clicking sounds recorded at seven sampling frequencies in total of 44.1 kHz, 32 kHz, 22.05 kHz, 16 kHz, 11.025 kHz, 8 kHz, and 4 kHz were compared with one another. It was found from the result of comparison that 16 kHz was the lower limit of the sampling frequency. Then, the sampling frequency was set to 16 kHz.
Then, a dummy signal having a frequency substantially the same as the sampling frequency was superimposed on an output signal from optical power meter 50 having a frequency component around 10 Hz in audio mixer 62.
An output signal from optical power meter 50 (an analog signal output) contains a large amount of direct-current voltage components. Therefore, when an output signal from optical power meter 50 is input to the audio input portion in PC 80 as it is, the direct-current voltage components may be lost. The dummy signal is used as a carrier wave for avoiding such an unfavorable condition.
Specifically, the output signal from optical power meter 50 is converted to an alternating-current signal which can be handled by an audio amplifier as a result of superimposition with a dummy signal. The output signal from optical power meter 50 can thus be input to PC 80 through the audio input function contained in PC 80 or an external audio input unit.
A frequency of the dummy signal is determined based on frequency characteristics of the audio input portion or the audio input unit. Though the frequency of the dummy signal is normally set to a frequency not lower than 16 kHz and not higher than 40 kHz, it should only be within a range permitting audio input so long as the frequency does not affect analysis of swallowing movement, and it may be lower than 16 kHz (for example, 100 Hz).
By subjecting the output signal from optical power meter 50 on which the dummy signal had been superimposed and the output signal from audio mixer 60 to digital sampling in the audio input portion of PC 80, they were converted to data in a WAV (resource interface file format (RIFF) waveform audio format) format. The resultant data was shown as being aligned on the same time axis, by using audio analysis software.
Referring to
As shown in
When a frequency of a carrier wave (dummy signal) is the same as the sampling frequency, accurate measurement of the carrier wave must fail in principles. The reason why the carrier wave is shown with CH1 in
Decrease in quantity of received light is observed at timing of observation of the clicking sound also in the present modification and it was confirmed that optical fiber sheet 10 and microphone 20 captured swallowing movement of the subject in good agreement with each other. Thus, a PC with a common audio input function can be used to compare two output waveforms without using an expensive apparatus such as a digital oscilloscope. Therefore, swallowing movement can accurately be detected and analyzed with a simplified apparatus configuration.
[Fifth Modification]
Other configuration examples of outside shape variation sensor 5 will be described in a fifth modification. As set forth above, outside shape variation sensor 5 is configured to detect variation in outside shape of the laryngeal portion associated with swallowing movement.
A swallowing movement monitoring sensor system 220 shown in
Pressure-sensitive sensor sheet 90 refers to a pressure-sensitive sensor of a capacitance type formed like a sheet. The pressure-sensitive sensor of the capacitance type converts variation in capacitance caused by deformation of a movable electrode of a capacitor due to an external pressure into an electric signal. In the example in
Pressure-sensitive sensor sheet 90 converts a measured pressure into an electric signal and outputs the electric signal. An output signal from pressure-sensitive sensor sheet 90 is amplified by an electric amplifier 95 and thereafter a dummy signal is superimposed on the output signal in audio mixer 62. The output signal on which the dummy signal has been superimposed is input to channel CH1 of an audio input of PC 80.
A detection signal indicating swallowing sound detected by microphone 20 is input to channel CH2 of the audio input of PC 80 through audio mixer 60. PC 80 analyzes two pieces of output waveform data input to channels CH1 and CH2 by driving analysis software installed in advance.
A swallowing movement monitoring sensor system 230 shown in
Pressure-sensitive rubber sensor sheet 92 is pressure-sensitive rubber formed like a sheet. Pressure-sensitive rubber converts variation in electrical resistance value generated as a result of displacement of conductive rubber by an external pressure into an electric signal. In the example in
Pressure-sensitive rubber sensor sheet 92 converts a measured pressure into an electric signal and outputs the electric signal. An output signal from pressure-sensitive rubber sensor sheet 92 is amplified by electric amplifier 95 and thereafter a dummy signal is superimposed on the output signal in audio mixer 62. The output signal on which the dummy signal has been superimposed is input to channel CH1 of the audio input of PC 80.
A detection signal indicating swallowing sound detected by microphone 20 is input to channel CH2 of the audio input of PC 80 through audio mixer 60. PC 80 analyzes two pieces of output waveform data input to channels CH1 and CH2 by driving analysis software installed in advance.
[Sixth Modification]
Swallowing of food and respiration have been known to be in precise coordination with each other (for example, Harold G. Preiksaitis et al., J Appl Physiol 81: 1707-1714, 1996). According to this publication, normally, a state that respiration temporarily ceases appears at the time of swallowing. The state that respiration temporarily ceases with swallowing is called “swallowing apnea.” Swallowing apnea is a function performed for preventing a lump of food from entering a trachea or a bronchus (aspiration).
When the swallowing function is normal, usually, respiration once ceases with transition from exhalation to swallowing and exhalation is again performed after swallowing. A respiration pattern in the order of exhalation→swallowing (apnea)→exhalation is observed. In contrast, when the swallowing function is deteriorated, a respiration pattern before and after swallowing may be disordered. For example, when inhalation is performed instead of exhalation after swallowing, the possibility of aspiration accordingly increases. Therefore, if a respiration pattern in swallowing can accurately and easily be detected with dynamics of swallowing, it may greatly contribute to diagnosis of dysphagia and prevention of aspiration pneumonia.
Currently, inductive plethysmography using Respitrace Calibrator has been adopted for detecting a respiration pattern at the time of swallowing. Since this technique requires a relatively expensive apparatus, it is not necessarily easy to use the technique in general clinical scenes.
The present inventors have succeeded in detecting slight body movement caused by respiration with an optical fiber sheet as an apparatus for diagnosing the sleep apnea syndrome (for example, Seiko Mitachi et al., APSS-SLEEP 2010, Vol. 33, A139, 2010). The diagnosis apparatus can make determination as apnea, hypopnea, or body movement irrelevant to respiration (for example, turning over) based on variation in quantity of light caused by passage through an optical fiber sheet mounted on bedclothing.
Therefore, in a sixth modification, variation in outside shape of the chest associated with swallowing movement is detected with an optical fiber sheet. Specifically, by bringing an optical fiber sheet into press contact with the chest portion of a subject, expansion, contraction, and a still state of the chest, that is, inhalation, exhalation, and a breath cessation period, are observed.
Thus, a respiration pattern in swallowing can be detected in a non-invasive and simplified manner. By combining the detected respiration pattern in swallowing with dynamics of swallowing movement detected by the swallowing movement monitoring sensor according to the embodiment, the swallowing function can objectively be assessed.
Swallowing movement monitoring sensor 1A according to the sixth modification is the same as swallowing movement monitoring sensor 1 shown in
First outside shape variation sensor 5 is attached around the neck of subject 100 with the laryngeal portion being defined as the center. The optical fiber sheet (see
Microphone 20 is attached to the inside of an ear (in an external auditory meatus) of subject 100. Microphone 20 is configured to detect swallowing sound produced in the ear in association with swallowing movement.
Second outside shape variation sensor 6 is attached to the chest portion of subject 100. An optical fiber sheet is employed for second outside shape variation sensor 6. Second outside shape variation sensor 6 is configured to detect variation in outside shape of the chest associated with swallowing movement. Second outside shape variation sensor 6 may be attached to an abdominal portion instead of or in addition to the chest portion. A pressure-sensitive sensor sheet or a pressure-sensitive rubber sensor sheet may be employed for second outside shape variation sensor 6.
A detection signal indicating variation in outside shape of the laryngeal portion detected by first outside shape variation sensor 5, a detection signal indicating swallowing sound detected by microphone 20, and a detection signal indicating variation in outside shape of the chest detected by second outside shape variation sensor 6 are together input to signal processing unit 30. Signal processing unit 30 processes the detection signal output from each of outside shape variation sensors 5 and 6 and microphone 20.
Referring to
As described with reference to
Optical fiber sheets 10α and 10β are identical in basic construction to optical fiber sheets 10 and 10A to 10D in the embodiments above. As shown in
A constant quantity of light continuously supplied from light source portion 40α is incident on the input end of optical fiber 14 of optical fiber sheet 10α. Optical power meter 50α receives emission light transmitted through optical fiber 14 and measures a quantity of received light. The measured quantity of received light (an amount of attenuation) is varied in accordance with a lateral pressure applied to optical fiber sheet 10α with movement of the laryngeal portion of the subject. Optical power meter 50α converts the measured quantity of received light into an electric signal and inputs the resultant electric signal to channel CH1 of digital oscilloscope 70.
A constant quantity of light continuously supplied from light source portion 40β is incident on the input end of optical fiber 14 of optical fiber sheet 10β. Optical power meter 50β receives emission light transmitted through optical fiber 14 and measures a quantity of received light The measured quantity of received light (an amount of attenuation) is varied in accordance with a lateral pressure applied to optical fiber sheet 10β with movement of the chest of the subject. Optical power meter 50β converts the measured quantity of received light into an electric signal and inputs the resultant electric signal to a channel CH3 of digital oscilloscope 70.
Variation in quantity of received light (an amount of attenuation) measured with optical fiber sheet 10β is substantially in proportion to a lateral pressure applied to optical fiber 14 with movement of the chest. Therefore, it can be determined that movement of the chest is small when variation in quantity of received light is small and movement of the chest is great when variation in quantity of received light is low. In the present modification, expansion, contraction, and a still state of the chest, that is, inhalation, exhalation, and a breath cessation period, are determined based on variation in quantity of received light.
A detection signal indicating swallowing sound detected by microphone 20 is input to audio mixer 60. Audio mixer 60 adjusts a volume of the detected swallowing sound and inputs the adjusted detection signal to channel CH2 of digital oscilloscope 70.
Digital oscilloscope 70 receives an output signal from optical power meter 50α at channel CH1, receives an output signal from audio mixer 60 at channel CH2, and receives an output signal from optical power meter 50β at channel CH3. Digital oscilloscope 70 holds variation over time (output waveform) of the output signals from optical power meters 50α and 50β and the output signal from audio mixer 60, for example, as voltage waveform data. Digital oscilloscope 70 transmits three output waveforms to PC 80.
Digital oscilloscope 70 can also show the three output waveforms as being aligned on the same time axis. Digital oscilloscope 70 is configured to be able to show the output waveform of the detection signal from microphone 20 and the output waveforms of the detection signals from optical fiber sheets 10α and 10β as being aligned on the same time axis.
PC 80 analyzes three pieces of output waveform data transmitted from digital oscilloscope 70 by driving analysis software installed in advance. A result of analysis by PC 80 is shown on a display apparatus (not shown) such as a CRT or a printer.
According to the configuration as above, swallowing movement monitoring sensor system 240 can simultaneously and non-invasively capture variation in outside shape of the laryngeal portion and swallowing sound involved with swallowing movement of the subject as well as variation in outside shape of the chest involved with swallowing movement with a simplified configuration. Thus, swallowing movement and a respiration pattern in swallowing can non-invasively and objectively be measured. Consequently, the swallowing function can objectively be assessed even in facilities lacking sufficient medical equipment or staff and hence great contribution to development of medical care can be achieved.
It should be understood that the embodiments above are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims rather than the description above and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.
1, 1A swallowing movement monitoring sensor; 10, 10A to 10D, 10α, 10β optical fiber sheet; 12 sheet-like member; 14 optical fiber; 14a linear portion; 14b curved portion; 14c annular portion; 14i, 14i1, 14i2 input end; 14o, 14o1, 14o2 output end; 20 microphone; 30 signal processing unit, 40, 40α, 40β light source portion; 50, 50α, 50β optical power meter; 60, 62 audio mixer; 64 dummy signal generator; 70 digital oscilloscope; 80 PC; 90 pressure-sensitive sensor sheet; 92 pressure-sensitive rubber sensor sheet; 95 electric amplifier; 100 subject; 102 nasal cavity; 104 tongue; 106 pharyngeal portion; 108 laryngeal portion; 110 trachea; 112 esophagus; 114 ear; 116 external auditory meatus; 200, 210, 220, 230, 240 swallowing movement monitoring sensor system
Filing Document | Filing Date | Country | Kind |
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PCT/JP2015/073530 | 8/21/2015 | WO | 00 |