JP2007275349A - System and method of screening sleep apnea syndrome, and operation program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately find a person who is suspected of having a sleep apnea syndrome (SAS) without using a posture sensor. <P>SOLUTION: An SAS screening system SO is provided with: a measurement means 11 which measures SpO<SB>2</SB>information from a fingertip etc. of a subject; an arithmetic processing means 12 which obtains an ODI value by performing prescribed data analysis processing to measurement data; and a display means 13 which displays the ODI value. In the arithmetic processing means 12, an analysis processing means 121 generates time series data of SpO<SB>2</SB>, a Dip detection means 122 detects Dip from the time series data, a time zone extraction means 123 extracts a Dip consecutive occurrence time zone, and thereafter an ODI detection means 124 obtains the ODI value in the Dip consecutive occurrence time zone. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a system, method, and operation program for screening for sleep apnea syndrome (SAS) based on measurement data relating to blood oxygen saturation in a living body.

SAS, which causes various symptoms from sleep apnea and hypopnea, not only triggers hypertension, cerebrovascular disorder and ischemic heart disease, but also causes decreased productivity and serious occupational accidents associated with sleepiness. In recent years, it has become a social problem. As one of the screening methods for SAS, there is a method of measuring a change in arterial oxygen saturation (referred to herein as “SpO ₂ ” or “blood oxygen saturation”) during sleep of a subject. This is because when there is an apnea or hypopnea state, oxygen supply is not performed and blood oxygen saturation is reduced.

  Conventionally, a pulse oximeter is known as a device for measuring blood oxygen saturation. For example, this pulse oximeter projects light toward a living body (finger) by attaching a probe including a light emitting unit and a light receiving unit to a subject's finger, and pulses a change in the amount of light passing through the living body. A time change of blood oxygen saturation is obtained by measuring as a signal and moving average of measured values every second (see, for example, Patent Document 1 and Patent Document 2). Then, the severity of SAS is determined by determining the number of occurrences of Dip, which is a peak of decrease in blood oxygen saturation associated with apnea. As a diagnostic index for such severity, ODI (Oxygen desaturation index; the number of occurrences of peak decrease in blood oxygen saturation per hour) is generally used.

  If the subject is found to have an ODI value that exceeds a certain threshold as a result of the SAS screening using a pulse oximeter, the subject undergoes a close examination at a medical institution as a suspected SAS patient. It will be. In addition to the above-mentioned blood oxygen saturation, polysomnography that detects evaluation parameters such as brain waves, mouth / nasal airflow, snoring, chest / abdominal movements, and body position as diagnostic indicators used exclusively in medical institutions ( There is AHI (Apnea Hipopnea Index; number of apnea and hypopnea per hour) derived using PSG (polysomnography).

By the way, the occurrence of apnea symptoms in SAS patients is dependent on body position. That is, as shown in FIG. 17 (a), during sleep in the supine position, the pharyngeal cavity is likely to be blocked by the sinking of the tongue base and soft palate, and the upper airway is blocked, and apnea symptoms tend to appear. On the other hand, as shown in FIG. 17 (b), since the tongue base and the soft palate are less likely to sink during sleeping in the lateral position or the prone position, the upper airway is maintained, and apnea symptoms are relatively unlikely to appear.
JP-A-1-153139 US Pat. No. 6,529,752

  The main purpose of SAS screening is to provide an opportunity to trap a person suspected of SAS in as wide a range as possible and to undergo a close examination at a medical institution or the like. ODI is a useful index that can be obtained in a state close to daily sleep at home by using a pulse oximeter that can be measured simply by attaching a probe to a finger. However, as described above, the occurrence of apneic symptoms is dependent on body posture, so if the subject has a long time sleeping in the supine or prone position on the day of the SAS screening, Since the number of occurrences of Dip decreases, the ODI value may be detected low. As a result, even though the subject is actually a SAS patient, this may be overlooked, which is contrary to the main purpose of the SAS screening.

  Therefore, a method has been proposed in which blood oxygen saturation is measured in association with the body position of the subject, and ODIs according to body position such as lateral position, prone position, and supine position are obtained. According to this method, it is possible to separately evaluate the ODI (the supine position ODI) in the supine position sleep in which apnea symptoms are likely to occur. However, in order to carry out this method, it is necessary to attach a body position sensor such as an acceleration sensor to the trunk (the body position cannot be detected at the end of the fingertip, etc.), the burden on the subject is heavy, and the fingertip is exclusively used. A cable connecting the pulse oximeter and the acceleration sensor mounted in the vicinity is necessary, and the complexity is undeniable. Although the use of the cable can be omitted by incorporating an acceleration sensor in the pulse oximeter, in this case, since the pulse oximeter is attached to the trunk, the burden on the subject is further increased.

  Further, in Patent Document 2 listed above, the measurement data of blood oxygen saturation obtained during the whole sleep period of the subject by the pulse oximeter is divided into unit time sections by switch operation, and then the unit time. A method of counting events such as Dip for each partition is disclosed. According to this method, the possibility of trapping the SAS suspect can be increased by obtaining the ODI value for each unit time section. However, even if this method is adopted, there is a possibility that the SAS suspect cannot be accurately identified in a case where the ratio of the sleeping time on the supine position is small simply by dividing the measurement data into unit time.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a SAS screening system, a method, and an operation program thereof that can accurately identify a person who is suspected of having SAS without using a posture sensor. And

  The sleep apnea syndrome screening system according to claim 1 of the present invention includes a measurement unit that detects measurement data related to blood oxygen saturation of a subject, and a predetermined data analysis for the measurement data acquired by the measurement unit. Analysis processing means for generating time series data of blood oxygen saturation by performing processing, and Dip that is a predetermined decrease peak of blood oxygen saturation is detected from the time series data of blood oxygen saturation Dip detecting means for performing, a time zone extracting means for extracting a Dip continuous occurrence time zone in which the Dip is continuously generated under a predetermined condition from the time series data, and a Dip generated in the Dip continuous occurrence time zone ODI calculating means for obtaining a first ODI value that is a Dip occurrence rate per unit time from the number of times of the above and the extracted time sum of the Dip continuous occurrence time period; Characterized by comprising a display means for displaying the first ODI value.

  According to this configuration, the continuous Dip generation time zone in which Dip is continuously generated under the predetermined condition is extracted by the time zone extraction unit. It can be said that this time zone is a time zone in which a person who is a so-called obstructive SAS patient has a very high possibility of sleeping in the supine position. That is, it can be said that the first ODI value obtained from the number of Dips generated in this Dip continuous occurrence time zone and the time sum of the Dip continuous occurrence time zones is substantially equal to the supine position ODI value. Can do. Therefore, even if the subject has a large sleeping time ratio in the supine position or prone position on the day of the SAS screening, it is possible to acquire data that can accurately evaluate whether or not there is a suspicion of SAS. Become.

  In the above configuration, it is determined whether or not the time sum of the Dip continuous occurrence time period has a predetermined time length. It is desirable to include determination means for giving an instruction signal for performing an operation for obtaining the ODI value.

  When the time sum of the Dip continuous occurrence time zone is too short, the first ODI value derived based on the time sum has a high ratio of error factors and a low reliability value. According to this configuration, in such a case, the first ODI value is not calculated, and only when the certain reliability can be ensured (when the time sum has a predetermined time length), the first Since the ODI value is calculated, the reliability of the first ODI value can be improved.

  Further, in the above configuration, further comprising display control means for controlling the display operation of the display means, wherein the ODI calculation means is based on the total time of the time series data and the total number of Dips detected by the Dip detection means. The second ODI value that is the Dip occurrence rate per unit time can be obtained, and the display control means causes the display means to display the first ODI value and / or the second ODI value. It is desirable to have a configuration (claim 3).

  According to this configuration, not only the first ODI value that can be said to be an ODI value by body position, but also a second ODI value that is a normal ODI value obtained for the entire sleep period of the subject is obtained and displayed. It can be displayed on the means. In severe SAS patients and central SAS patients, the occurrence of apnea symptoms is generally not position dependent. On the other hand, in the case of moderate and mild SAS patients, there is position dependency. Therefore, it is possible to identify these patients by determining two ODI values.

  In this case, the display control means compares the first ODI value with the second ODI value, and when the second ODI value is smaller than a predetermined value compared to the first ODI value, the display control means The first ODI value can be displayed by adding predetermined identification information to the means.

  As described above, the first ODI value can be evaluated to be approximately equal to the value of the supine position ODI. Therefore, for example, while the second ODI value is treated as an ODI value for the same total sleep time of the subject as before, the first ODI value is attached with identification information such as “an ODI value by body position”. If it is made to display, a user's convenience can be improved.

  In any one of the configurations described above, it is desirable that the display control means displays the time sum of the Dip continuous occurrence time zone on the display means in addition to the first ODI value. According to this configuration, since the time sum of the Dip continuous occurrence time zone is displayed on the display means, the reliability of the obtained first ODI value can be roughly estimated based on the time length. .

  The sleep apnea syndrome screening method according to claim 6 of the present invention includes a step of detecting measurement data relating to blood oxygen saturation of a subject, and performing a predetermined data analysis process on the measurement data to perform blood measurement. A step of generating time series data of oxygen saturation, a step of detecting Dip which is a predetermined decrease peak of blood oxygen saturation from the time series data of blood oxygen saturation, and the time series data , A step of extracting a Dip continuous occurrence time zone in which the Dip is continuously generated under a predetermined condition, a number of Dips generated in the Dip continuous occurrence time zone, and the extracted Dip continuous occurrence time zone And a step of obtaining an ODI value which is a Dip occurrence rate per unit time from the time sum.

  An operation program of the sleep apnea syndrome screening system according to claim 7 of the present invention is provided in a computer provided in the calculation processing means of the sleep apnea syndrome screening system including predetermined calculation processing means and display means. Obtaining measurement data on blood oxygen saturation of the subject, generating time series data of blood oxygen saturation by performing predetermined data analysis processing on the measurement data, and blood oxygen A step of detecting Dip, which is a predetermined decrease peak of the blood oxygen saturation, from the time series data of the saturation, and the Dip continuous in which the Dip is continuously generated from the time series data under a predetermined condition Extracting the occurrence time zone, the number of Dips occurring in the Dip continuous occurrence time zone, and the extracted Di And a time sum of consecutive occurrences time zone, and wherein determining a ODI value is Dip generation rate per unit time, the said ODI value be executed and a step of displaying on the display means.

  According to the inventions according to claim 1, claim 6 and claim 7, ODI as a clinically meaningful evaluation value that can accurately evaluate whether or not there is a suspicion of SAS without depending on the body position sensor. The value can be obtained. Therefore, it is possible to provide a SAS screening system, method, and operation program that have a much lower possibility of overlooking a subject suspected of SAS than in the conventional method.

  According to the invention of claim 2, since the reliability of the first ODI value can be improved, it is possible to evaluate whether or not there is a suspicion of SAS more accurately.

  According to the invention according to claim 3, by obtaining the two ODI values of the first ODI value and the second ODI value, there is no dependency on the position of the patient who is dependent on the sleeping position for the occurrence of apnea symptoms. The patient can be identified, and the usability of the system can be improved.

  According to the fourth aspect of the present invention, for example, the first ODI value can be displayed as the “body-specific ODI value”, so that the convenience for the user can be improved.

  According to the invention of claim 5, since the reliability of the obtained first ODI value can be roughly estimated based on the time length of the time sum displayed on the display means, the necessity for remeasurement, etc. Can be easily determined.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram schematically showing the configuration of the SAS screening system S0 according to the embodiment of the present invention. This SAS screening system S0 is a measuring means 11 that measures blood oxygen saturation (SpO ₂ ) information from a subject's fingertip or the like, and an arithmetic processing that performs a predetermined data analysis process on the measurement data acquired by the measuring means 11 Means 12, a display means 13 for displaying the ODI value (first ODI value) obtained by the arithmetic processing means 12, and a storage means 14 for storing the measurement data and the like.

The measuring means 11 is not particularly limited as long as it can measure parameters related to the subject's SpO ₂ information. The measuring means 11 includes a predetermined sensing element, a driving circuit for the sensing element, and a measurement circuit that performs signal processing (A / D conversion or the like) on a measurement signal output from the sensing element. For example, when SpO ₂ is measured based on two-wavelength photoelectric pulse wave data, a light-emitting element such as an LED (two-wavelength LED) and a light-receiving element such as a silicon light-receiving element are used as the sensing element.

  The arithmetic processing means 12 includes a ROM (Read Only Memory) that stores a control program, a RAM (Random Access Memory) that temporarily stores data, and a central processing unit (CPU) that reads and executes the control program from the ROM. Or a DSP (Digital Signal Processor) or the like, and functionally includes an analysis processing unit 121, a Dip detection unit 122, a time zone extraction unit 123, and an ODI detection unit 124.

The analysis processing unit 121 obtains the SpO ₂ value (instantaneous SpO ₂ value) for each sampling period based on the measurement data acquired by the measuring unit 11, for example, the two-wavelength photoelectric pulse wave data, and calculates the instantaneous SpO ₂ value as time. Expand on the axis to generate SpO ₂ time series data.

Dip detecting means 122, from the time-series data of the SpO ₂ obtained by analysis processing means 121, detects the Dip (temporary drop) is a predetermined reduction peak of the SpO _2. Here, Dip does not indicate that the SpO ₂ value has decreased below a predetermined threshold value, but is larger than the SpO ₂ value (baseline) at an arbitrary point in time within a predetermined time. It shall refer to the case where a downward tendency is shown (details will be given later).

The time zone extracting means 123 extracts the Dip continuous occurrence time zone in which the Dip is continuously generated under a predetermined condition from the SpO ₂ time series data. The standard for time zone extraction may be set as appropriate. However, if a normal SAS patient has apnea symptoms at intervals of about 1 minute at the longest, for example, about 1 to 5 minutes after one Dip is detected. The time zone in which the pattern in which the next Dip is detected within three consecutive times can be set to be extracted as the Dip continuous occurrence time zone.

  The ODI detecting means 124 obtains the number of Dips generated in the Dip continuous occurrence time zone and the time sum of the extracted Dip continuous occurrence time zones, and divides the Dip number by the time sum to obtain per unit time. An operation is performed to obtain an ODI value that is the Dip occurrence rate.

  The display means 13 includes a display device such as a liquid crystal display (LCD), a 7-segment LED, an organic photoluminescence display device, a CRT (Cathode Ray Tube), and a plasma display device. The display means 13 displays at least the ODI value obtained by the ODI detection means 124, and displays the time sum of the Dip continuous occurrence time zone as necessary. Information, image information, light lighting information, and the like are displayed in any form as necessary.

  The storage means 14 temporarily stores the pulse wave data measured by the measurement means 11, the data analysis result by the arithmetic processing means 12, and the like. As this storage means 14, RAM, EPROM (Erasable and Programmable ROM) or the like can be used.

  An operation example of the SAS screening system S0 configured as described above will be briefly described. When the measurement is started, the biological information is measured at every predetermined sampling period by the measurement means 11 and the measurement data is output. The measurement data is subjected to signal processing such as A / D conversion and then stored in the storage means 14 in association with time information. Such measurement operation is repeated during the measurement period, and the measurement data is accumulated in the storage unit 14.

After the measurement is completed, the measurement data in the storage means 14 is read out by the arithmetic processing means 12 and ODI is calculated. Specifically, SpO ₂ time series data is generated by the analysis processing unit 121, Dip is detected from the time series data by the Dip detection unit 122, and Dip continuous occurrence time zones are extracted by the time zone extraction unit 123. Above, the ODI detection means 124 obtains the ODI value in the Dip continuous occurrence time zone. The obtained ODI value is displayed on the display means 13 in an appropriate display form.

  According to such a SAS screening system S0, the Dip continuous occurrence time zone is extracted before the ODI value is calculated. This time zone can be treated as a time zone including a time zone sleeping in the supine position in the case of moderate and mild SAS patients. That is, the first ODI value obtained from the number of Dips generated in this Dip continuous occurrence time zone and the time sum of the Dip continuous occurrence time zones is substantially equal to the value of the supine position ODI. Therefore, even if the subject has a large sleeping time ratio in the lateral position or the prone position on the day of the SAS screening, it is possible to acquire data that can accurately evaluate whether or not there is a suspicion of SAS. Therefore, it is possible to provide the SAS screening system S0 that has a very low possibility of overlooking a subject suspected of SAS as compared with the conventional method.

  When providing the SAS screening system S0 described above as an actual machine, various hardware configurations can be adopted. FIG. 2 shows an external configuration of a SAS screening system S1 in which the measurement unit 11, the arithmetic processing unit 12, the display unit 13, and the storage unit 14 are mounted on a pulse oximeter 20 that is a single device that can be worn by a subject. FIG. This pulse oximeter 20 (SAS screening system S1) includes a pulse oximeter main body 21 that can be attached to the wrist of a subject and a probe 22 that can be attached to the fingertip of the subject, both of which are signal cables. 201 is electrically connected.

  The pulse oximeter main body 21 is provided with a power switch 211, a display unit 212 (corresponding to the display unit 13) made up of an LCD and the like, a belt locking unit 213, and the like. An electric circuit that performs a function corresponding to the arithmetic processing means 12 and the storage means 14 is housed. Further, the probe 22 is provided with a light emitting element and a light receiving element that constitute a part of the measuring means 11. According to the SAS screening system S1, since the system is configured as a wearable single device equipped with all necessary functions, a compact system with excellent portability can be obtained.

  FIG. 3 shows another hardware configuration example of the system according to the present invention, in which a pulse oximeter 20 ′ that can be attached to a subject and a personal computer PC are connected by a communication cable C such as a USB cable. It is an external appearance block diagram which shows system S2. In this SAS screening system S2, the functions of the measuring means 11 and the storage means 14 are provided in the pulse oximeter 20 ′, and the functions of the arithmetic processing means 12 and the display means 13 are provided in the personal computer PC (of course, the pulse oximeter The meter 20 ′ may also have the functions of the arithmetic processing means 12 and the display means 13). With such a SAS screening system S2, measurement data can be downloaded from the storage means 14 and advanced data analysis can be performed by the personal computer PC.

  Hereinafter, an example of a more specific embodiment of the hardware-configured SAS screening system S1 shown in FIG. 2 will be described. FIG. 4 is a block diagram showing an electrical configuration of the pulse oximeter 20 shown in FIG. The probe 22 of the pulse oximeter 20 includes a light emitting unit 221 and a light receiving unit 222, and the pulse oximeter body unit 21 includes a measurement circuit unit 30, a control unit 40, a memory unit in addition to the display unit 212. 51, an operation unit 52, an I / F unit 53 (communication unit), and a power supply unit 54 are provided.

  The light emitting unit 221 includes LEDs that generate two different wavelengths λ1 and λ2. For example, a red LED that generates red light having a wavelength λ1 in the red region and an infrared that generates infrared light having a wavelength λ2 in the infrared region. LEDs are used. On the other hand, the light receiving unit 222 includes a photoelectric conversion element that receives the light emitted from the light emitting unit 221 and generates a current corresponding to the received light intensity. As the photoelectric conversion element, a light receiving element such as a silicon photodiode having a light sensitivity to at least the wavelength λ1 and the wavelength λ2 can be used.

The light emitting unit 221 and the light receiving unit 222 are arranged opposite to each other so as to detect the transmitted light of the living body with the living tissue (for example, fingertip) for measuring SpO ₂ interposed therebetween, or adjacently arranged so that the reflected light from the living body can be detected. Is done. As a result, light of both wavelengths λ1 and λ2 emitted from the light emitting unit 221 is received by the light receiving unit 222 after passing through the living body, and two-wavelength photoelectric pulse wave data is acquired.

  The measurement circuit unit 30 includes a light emission control circuit 31 connected to the light emitting unit 221 and an A / D conversion circuit 32 connected to the light receiving unit 222. The light emission control circuit 31 performs control to cause the red LED and the infrared LED of the light emitting unit 221 to emit light alternately based on a light emission control signal given at a predetermined sampling period from a measurement control unit 41 of the control unit 40 described later. Thereby, red light (λ1) and infrared light (λ2) are alternately emitted from the light emitting unit 221. The A / D conversion circuit 32 is similarly controlled by the measurement control unit 41, acquires a photoelectric conversion signal (measurement signal) output from the light receiving unit 222 in synchronization with the light emission of the light emitting unit 221, and converts this into a digital signal. The data is converted and output to the control unit 40.

Oxygen is transported by oxidation / reduction of hemoglobin in the blood. When this hemoglobin is oxidized, the absorption of red light (λ1) decreases and the absorption of infrared light (λ2) increases. Conversely, when it is reduced, the absorption of red light (λ1) increases and the infrared light increases. It has an optical characteristic that absorption of light (λ2) decreases. The probe 22 and the measurement circuit unit 30 are configured to use this characteristic, and by measuring fluctuations in the amount of transmitted light of the red light (λ1) and infrared light (λ2) detected by the light receiving unit 222. , SpO ₂ can be obtained.

  The control unit 40 is composed of a CPU or the like, and controls the operation of each unit housed in the pulse oximeter main body 21. Functionally, the measurement control unit 41, the recording control unit 42, the arithmetic processing unit 43, and the display control are performed. A portion 44 is provided.

  The measurement control unit 41 controls the measurement operation by the light emitting unit 221 and the light receiving unit 222 according to a predetermined measurement program. Specifically, a timing pulse or the like is given to the light emission control circuit 31 and the A / D conversion circuit 32 to cause the light emitting unit 221 to emit light at every sampling period, and from the light receiving unit 222 in synchronization with the light emission timing. (Measurement data) is acquired.

  The recording control unit 42 controls the operation of recording the digital measurement data output from the A / D conversion circuit 32 in the memory unit 51 in association with the measurement time information, using a timer function or the like provided in the CPU.

  The arithmetic processing unit 43 uses the photoelectric pulse wave data acquired by the probe 22 and once stored in the memory unit 51 (or directly with respect to the photoelectric pulse wave data acquired by the probe 22) to obtain the ODI value. Perform data analysis processing. The detailed functional configuration of the arithmetic processing unit 43 will be described in detail later with reference to FIG.

  The display control unit 44 causes the display unit 212 to display status information during measurement (pilot information indicating that measurement is in progress) or an ODI value obtained by the arithmetic processing unit 43 in a predetermined display form. Control display behavior. A specific example of the display mode will be described later with reference to FIG.

  The display unit 212 includes an LCD (Liquid Crystal Display) display device or the like, and displays the above-described state information during measurement and analysis results according to cases as appropriate, such as letters / numbers / symbols, pictograms, and character information. Displayed as information.

The memory unit 51 includes a nonvolatile memory such as a ROM, an EEPROM, or a flash memory. The memory unit 51 stores an operation program or the like of the pulse oximeter 20 and stores measurement data acquired by the pulse oximeter 20. That is, the memory unit 51 temporarily stores the two-wavelength photoelectric pulse wave data provided from the measurement circuit unit 30 or the instantaneous SpO ₂ value obtained from the two-wavelength photoelectric pulse wave data in association with the sampling time.

  The operation unit 52 includes operation buttons and the like, and is used for inputting a measurement start instruction and various operation instruction information to the control unit 40. The I / F unit 53 is an interface device that enables data communication when transferring data recorded in the memory unit 51 to another electrical device such as a personal computer. The power supply unit 54 includes a predetermined power supply circuit, a power supply battery such as a button battery, and the like, and supplies a drive voltage to each functional unit of the pulse oximeter 20.

Next, a detailed configuration of the arithmetic processing unit 43 will be described. FIG. 5 is a functional block diagram showing a functional configuration of the arithmetic processing unit 43. This arithmetic processing unit 43 functionally includes a preprocessing unit 431, an SpO ₂ data generation unit 432 (analysis processing unit), a Dip detection unit 433 (Dip detection unit), a time zone extraction unit 434 (time zone extraction unit), A determination unit 435 (determination unit) and an ODI calculation unit 436 (ODI calculation unit) are provided.

  The pre-processing unit 431 reads out the photoelectric pulse wave data acquired in the memory unit 51 at a predetermined sampling period and stored in association with time information, performs data alignment processing that develops on the time axis, and performs the above-described red light ( A photoelectric pulse waveform is generated for each of the two wavelengths λ1) and infrared light (λ2). FIG. 6 is a graph showing an example of the photoelectric pulse wave waveform 61 generated by the preprocessing unit 431 for one wavelength (pulse wave sampling frequency = 30 Hz).

  Further, the preprocessing unit 431 performs noise removal processing and moving average processing on the photoelectric pulse wave waveform 61. The photoelectric pulse wave waveform 61 shown in FIG. 6 is obtained by plotting raw pulse wave data as it is, but such raw photoelectric pulse wave waveform 61 often shows fluctuations in pulse wave data in a minute measurement time range. . For this reason, the pre-processing unit 431 performs, for example, an arithmetic operation for calculating five moving averages of the pulse wave data plotted on the time axis (determining the average of the central data and the two data before and after it) as a photoelectric pulse wave waveform. A moving average process sequentially performed along the 61 time axis is performed.

The SpO ₂ data generation unit 432 obtains an instantaneous SpO ₂ value for each sampling period from the two-wavelength photoelectric pulse wave waveform (waveform data processed by the preprocessing unit 431), and develops this on the time axis, thereby expanding the SpO ₂ data. _An SpO ₂ curve that is time-series data of ₂ is generated. FIG. 7 is a graph showing an example of such an SpO ₂ curve 62 (time axis is divided into an upper stage and a lower stage). In the SpO ₂ curve 62, a portion where the SpO ₂ value temporarily falls is observed, which is the above-mentioned Dip.

Dip detection unit 433, based on time-series data of the SpO ₂ (SpO ₂ curve 62) performs an operation for detecting the Dip is the reduction peak of the SpO ₂ values. Further, the Dip detection unit 433 determines whether or not the detected Dip is a significant Dip associated with the subject's apnea or hypopnea state. That is, the Dip detection unit 433 has a predetermined Dip detection index, and determines whether or not it is a “significant Dip” by comparing the detected Dip with the Dip detection index.

Detecting Dip corresponds to detecting an apnea or hypopnea event regarding the SpO ₂ curve 62 acquired for the subject. FIG. 8 is a diagram schematically illustrating a Dip detection index. As the Dip detection index, for example, a decrease slope, a decrease degree, a decrease state duration, a recovery time (an increase degree) of the SpO ₂ curve 62, and the like are used. For example, as illustrated in FIG. 8, the Dip detection unit 433 determines that a Dip extracted from the SpO ₂ curve 62 is “significant Dip” when the following requirement is satisfied.
Duration: 8 to 120 seconds
Decreasing slope: ≧ 1% / 10sec
Degree of decrease: ≧ 2% to ≧ 5%
Recovery time; <20 sec

The Dip calculated here is not the degree of decrease from a certain reference value, but the degree of decrease from an arbitrary point (any time point during the sleep period of the subject; baseline) of the SpO ₂ curve 62 that varies sequentially. Is based. That is, rather than seeing whether the SpO ₂ value has decreased by a predetermined amount compared to the SpO ₂ value at the beginning of measurement or whether the SpO ₂ value has fallen below a certain value, what is the degree of decrease from the start point of each Dip? The degree of detection is used as a detection index. As a result, a decrease in the SpO ₂ value can be accurately detected.

The time zone extraction unit 434 extracts, from the SpO ₂ curve 62, Dip continuous occurrence time zones in which the Dip is continuously generated under a predetermined condition. As described above, the extraction criterion is, for example, a time period in which a pattern in which the next Dip is detected is continued three times or more within about 1 to 5 minutes after one Dip is detected, Can be set to extract as

The significance of providing such a time zone extraction unit 434 will be described. FIG. 9 is a trend graph of SpO ₂ based on two-wavelength photoelectric pulse wave data acquired by one measurement (total sleep time = about 2.3 hours) for a certain subject. Here, by dividing the data in one hour increments, SpO ₂ according to SpO ₂ curve 63 according to the first 1 hour as a (1) a period in the upper, the next one hour as the (2) periods in the middle The curve 64 is shown in the lower part, and the SpO ₂ curve 65 relating to the remaining 17 minutes is shown as the (3) period. When doctors look at this trend graph, there is a suspicion of SAS in the subject because there is a period in which Dip is concentrated near the first half of the first (1) period and the middle of the second (2) period. It is possible to recommend a close examination such as PSG. However, in the SAS screening, when the determination based on the ODI value obtained for the total sleep time is performed, the subject may be treated as a healthy person.

FIG. 10 is a table format showing the number of Dip and the ODI value for the SpO ₂ curves 63 to 65 for each of the (1) to (3) periods. The lowermost column shows the number of Dips corresponding to the total sleep time and the ODI value. In this measurement example, the ODI value obtained by the conventional general SAS screening method is “12.7” because it is obtained for the total sleep time. Here, for example, when the threshold value for negative and positive for SAS = 15, the subject has a negative result despite the positive result of ODI value = 20 in the period (2). It will be output.

  Also, even if the ODI value is obtained in units of one hour periods, the period estimated to have a relatively long supine sleeping posture as in the example (2) period shown here does not appear. In the same manner, a negative ODI value is similarly derived. That is, if a significant dip is not detected due to the subject taking a prone sleep posture in the (2) period, it is a sign of SAS for a relatively short period of time in the (1) period. This is overlooked because the ODI value of the (1) period is equal to 8 even though dip is concentrated. Furthermore, even if the Dip concentration occurrence part appearing in the (2) period appears to shift over time and straddle the (2) period and the (3) period, it is negative in each period. There is a possibility of deriving a value. As described above, simply obtaining the ODI value for each unit time may not sufficiently achieve the purpose of the SAS screening for trapping a person suspected of SAS in as wide a range as possible.

Therefore, the time zone extraction unit 434 extracts the Dip continuous occurrence time zone based on the extraction criteria as described above. FIG. 11 is a graph showing only the Dip continuous occurrence time zone extracted from the SpO ₂ trend graph shown in FIG. That is, Dip continuous generation time zones t1 and t2 corresponding to Dip concentration generation units 631 and 632 in the SpO ₂ curve 63 are extracted from the (1) period. Further, from the (2) period, the Dip continuous generation time period t3 corresponding to the Dip concentration generation unit 641 in the SpO ₂ curve 64 is extracted. On the other hand, since there is no remarkable Dip concentration generation part in the (3) period, the Dip continuous generation time zone is not extracted. If the ODI value is obtained for the Dip continuous occurrence time zones t1 to t3 extracted in this way, a person suspected of SAS can be reliably trapped.

FIG. 12 is a time chart for explaining the Dip continuous occurrence time zone extraction algorithm in the time zone extraction unit 434. The time zone extraction unit 434 sequentially compares the instantaneous SpO ₂ values constituting the SpO ₂ curve 66 along the time axis to determine the magnitude, and determines the interval between adjacent Dips by determining the interval between adjacent Dips. Extract. From Dip1 that first appears in the SpO ₂ curve 66 by the magnitude determination process, the time t11 at which the instantaneous SpO ₂ value starts to decrease, the time t12 that indicates the decreased peak value, and the time at which the level before the start of the decrease is almost restored. t13 is detected. Similarly, at Dip2 and Dip3 appearing subsequently, times t21 to t23 and times t31 to t33 are detected.

  When the time zone extraction unit 434 recognizes Dip1 by the magnitude determination process from time t11 to time t13, the time zone extraction unit 434 stores this as the reference Dip. Subsequently, the interval ta from the restoration time t13 of Dip1 to the start time t21 of Dip2 is counted. If the interval ta ends within a predetermined threshold time (for example, 1 to 5 minutes), Dip1 and Dip2 are determined to be “continuous”, and a value of the number of consecutive = 2 is stored. If the interval ta does not end even if the threshold time is exceeded, the position of Dip1 as the reference Dip is reset. If Dip2 is subsequently recognized, that Dip2 is stored as the reference Dip.

  Subsequently, the time zone extraction unit 434 counts the interval tb from the restoration time t23 of Dip2 to the start time t31 of Dip3, and if the interval tb ends within the threshold time, it is determined as “continuous” from Dip1 to Dip3 and is continuous. A value of number = 3 is stored. Here, when “Dip continuation number = 3” is set as the extraction condition of the Dip continuous occurrence time zone, the time zone extraction unit 434 continuously generates Dip from the start time t11 of Dip1 to the restoration time t33 of Dip3. Recognize as a time zone. Thereafter, when the next Dip is recognized within the threshold time from the restoration time t33, the process of recognizing the Dip continuous occurrence time zone by extending to the restoration time is repeated.

  On the other hand, as shown in FIG. 12, when the interval tc continues from the restoration time t33 to the time tx that is the expiration time of the threshold time, the time zone extraction unit 434 causes the restoration time t33 of Dip3 from the start time t11. Is definitely recognized as one Dip continuous occurrence time zone. Thereafter, when the next Dip is recognized, the same processing as described above is performed. Note that the interval between Dips may be set between Dip start times and between Dip lowering peak value times.

  Returning to FIG. 5, the determination unit 435 determines whether the time sum of the Dip continuous occurrence time period has a predetermined time length, and when the predetermined time length has the predetermined time length, An instruction signal for giving the ODI calculation unit 436 an operation for obtaining the ODI value is given. This is because, when the time sum of the Dip continuous occurrence time zone is too short (for example), the ODI value derived based on the time sum has a high ratio of error factors and has low reliability.

  Specifically, in the example shown in FIG. 11, the determination unit 435 obtains the time sum of the Dip continuous occurrence time zones t1 to t3, and based on whether the time sum exceeds a preset threshold time. , It is determined whether or not to perform an operation for obtaining the ODI value. The threshold time of the time sum may be set arbitrarily, but can be set to about 20 to 30 minutes, for example. Further, according to the measurement time (total sleep time of the subject), for example, when the total sleep time is 4 hours, the threshold time may be set to 30 minutes, and when it is 6 hours or more, 1 hour may be set. Further, an appropriate threshold time may be input from the operation unit 52 (see FIG. 4) according to the personal characteristics of the subject.

  In response to the calculation instruction signal from the determination unit 435, the ODI calculation unit 436 obtains the number of Dips generated in the Dip continuous occurrence time zone and the time sum of the extracted Dip continuous occurrence time zones (or from the determination unit 435). By obtaining the time sum information) and dividing the number of Dip times by the time sum, an operation for obtaining the ODI value (first ODI value) in the Dip continuous occurrence time zone is performed. For example, when the Dip continuous occurrence time zone is extracted as in the example shown in FIG. 11, as shown in FIG. 13, the number of Dips generated in the Dip continuous occurrence time zones t1 to t3 is represented by this Dip continuous occurrence time. The first ODI value is obtained by dividing by the time sum t1 + t2 + t3 of the bands t1 to t3.

Further, the ODI calculation unit 436 calculates the total time (total sleep time) of the SpO ₂ time series data, that is, the SpO ₂ curves 63 to 65 shown in FIG. Based on the total number of times, it is also possible to obtain a second ODI value which is a so-called conventional ODI value. In severe SAS patients and central SAS patients, the occurrence of apnea symptoms is generally not position-dependent, but in moderate and mild SAS patients, there is position dependence. Therefore, it is possible to identify these patients by obtaining the first ODI value and the second ODI value.

  The display control unit 44 performs control for causing the display unit 212 to display predetermined information in addition to the first ODI value and / or the second ODI value. Specifically, the first ODI value is compared with the second ODI value. When the second ODI value is smaller than the first ODI value by a predetermined value, the first ODI value includes Identification information “other ODI” is added and displayed on the display unit 212. This is because the first ODI value can be treated as being approximately equal to the ODI value during sleep on the supine position. Thereby, a user's convenience can be improved.

  The display control unit 44 also causes the display unit 212 to display the time sum of the Dip continuous occurrence time period. By performing such display, the reliability of the obtained first ODI value can be roughly estimated based on the length of the time sum of the displayed Dip continuous occurrence time zone. Therefore, it is possible to easily determine the necessity for remeasurement or the like by the user.

  FIG. 14 is a plan view showing an example of a display mode of the SAS screening result on the display unit 212. Here, the value of “ODI” (corresponding to the second ODI value targeting the total sleep time), the value of “ODI by posture” (corresponding to the first ODI value targeting the Dip continuous occurrence time zone), An example is shown in which the value of “time sum” (corresponding to the time sum of the extracted Dip continuous occurrence time zone) is displayed numerically. Further, an example is shown in which an “evaluation” column is provided, and a message such as “please undergo a close inspection” is displayed together with a pictogram indicating the result.

  The operation of the pulse oximeter 20 (SAS screening system S1) configured as described above will be described based on the flowcharts shown in FIGS. FIG. 15 is a flowchart showing an overall operation flow of the pulse oximeter 20.

  First, the pulse oximeter 20 is attached to an appropriate portion (such as a wrist) of the subject's body, the probe 22 is clipped to the measuring finger, the power switch 211 (see FIG. 2) of the pulse oximeter 20 is turned on, and measurement is performed. The mode is set (step S1). After this, the measurement starts, but when performing pulse oximetry all night, considering the time until the subject goes to sleep, set the timer so that the measurement starts after a predetermined time has elapsed. Anyway.

  When the measurement is started, it is confirmed whether or not the predetermined sampling period is reached (step S2). When the sampling period comes (YES in step S2), the probe 22 acquires the two-wavelength photoelectric pulse wave data of the subject. (Step S3). Thereafter, after A / D conversion and predetermined calculation processing are performed by the A / D conversion circuit 32 (see FIG. 4), these measurement data are stored in the memory unit 51 of the pulse oximeter main body 21 in association with time information. (Step S4).

  Then, it is confirmed whether or not the measurement is finished (step S5), and if it is during the predetermined measurement period (NO in step S5), the process returns to step S2 and the process is repeated, and the measurement data is accumulated in the memory unit 51 Is done. On the other hand, when the predetermined measurement period ends or when the subject completely awakens during the predetermined measurement period and forcibly ends the measurement operation (YES in step S5), the pulse oximeter 20 is used here. The measurement operation that was performed ends.

  Thereafter, it is confirmed whether or not an operation signal instructing execution of an analysis mode for performing data analysis of the acquired photoelectric pulse wave data is given from the operation unit 52 (step S6). When the analysis mode execution instruction is given (YES in step S6), the photoelectric pulse wave measurement data stored in the memory unit 51 is read, and measurement data analysis corresponding to various cases is performed (step S7).

  FIG. 16 is a flowchart showing details of the measurement data analysis processing in step S7 of the flowchart of FIG. When the measurement data analysis is started, the measurement data stored in the memory unit 51 is read by the arithmetic processing unit 43 (see FIGS. 4 and 5) (step S11). Then, a predetermined process is performed by the preprocessing unit 431, and a photoelectric pulse wave waveform 61 as shown in FIG. 6 is generated for two wavelengths used for the measurement (step S12).

Subsequently, the SpO ₂ data generation unit 432 obtains an instantaneous SpO ₂ value for each sampling period from the two-wavelength photoelectric pulse wave waveform 61 obtained in Step S12, and develops this on the time axis, whereby FIG. An SpO ₂ curve 62 as shown in FIG. 6 is generated (step S13). Then, from this SpO ₂ curve 62, the “significant Dip” is detected by the Dip detecting unit 433 according to the Dip detection index as shown in FIG. 8, for example (step S14).

Next, the dip continuous generation time zone (see t1, t2, and t3 in FIG. 11), which is a time zone in which Dip is continuously generated under the predetermined condition in the SpO ₂ curve 62 by the time zone extraction unit 434. Extraction processing is performed (step S15). Further, a time sum of the extracted Dip continuous occurrence time zones (in the example of FIG. 11, time sum = t1 + t2 + t3) is obtained (step S16).

  Thereafter, the determination unit 435 determines whether or not the time sum obtained in step S16 has a time length sufficient to ensure a certain level of reliability (step S17). If the time sum has a predetermined time length (YES in step S17), the ODI calculation unit 436 causes the Dip concentration generation unit 631 in the Dip continuous generation time zones t1, t2, and t3 as shown in FIG. The number of Dips at 632 and 641 is counted (step S18), and the first ODI value is calculated by dividing this by time sum = t1 + t2 + t3 (step S19). On the other hand, when the time sum does not have the predetermined time length (NO in step S17), the above steps S18 and S19 are skipped.

Subsequently, the ODI calculation unit 436 confirms whether or not an instruction for obtaining an ODI value (second ODI value) for the total sleep time is given (step S20). When obtaining the second ODI value (YES in step S20), the ODI calculation unit 436 counts the number of Dips for the entire period of the SpO ₂ curve 62 (acquires the count value from the Dip detection unit 433) (step). S21), the second ODI is calculated by dividing this by the total sleep time (measurement total time) (step S22). On the other hand, if the instruction for obtaining the second ODI value is not given (NO in step S20), step S21 and step S22 are skipped.

  When the first ODI value and / or the second ODI value are obtained by the arithmetic processing unit 43 in this way, the display unit 44 displays the display unit in an appropriate display form (for example, see FIG. 14). The result is displayed at 212 (step S23).

  As mentioned above, although embodiment was described about this invention, this invention is not limited to this, For example, the deformation | transformation embodiment of following [1]-[3] can be taken.

[1] In the above-described embodiment, the Dip detecting means detects a Dip that shows a large decreasing tendency of a predetermined level or more within a predetermined time as compared to the SpO ₂ value (baseline) at an arbitrary time. Although shown, a predetermined threshold value may be set, and the SpO ₂ curve that is below the threshold value may be simply obtained as Dip.

[2] As an extraction algorithm by the time zone extraction means, for example, the measurement period is time-divided at intervals of about 5 minutes to 10 minutes, and the number of drop peak values based on Dip is calculated for each time-division period, which exceeds a predetermined number A method may be adopted in which a time division period in which the number of reduced peak values exists is extracted to obtain a Dip continuous occurrence time zone.

[3] As a form of providing the product according to the present invention, it is also possible to provide not only the above-described SAS screening systems S0, S1, and S2 but also an operation program that executes processing performed by these systems. Such a program can be recorded on a computer-readable recording medium such as a flexible disk attached to the computer, a CD-ROM, a ROM, a RAM, and a memory card, and provided as a program product. Alternatively, the program can be provided by being recorded on a recording medium provided in the personal computer PC shown in FIG. A program can also be provided by downloading via a network.

It is a block diagram which shows simply the structure of SAS screening system S0 which concerns on embodiment of this invention. 1 is an external configuration diagram showing a SAS screening system S1 including a pulse oximeter 20. FIG. It is an external appearance block diagram which shows SAS screening system S2 which is the other hardware structural example of the system which concerns on this invention. FIG. 3 is a block diagram showing an electrical configuration of the pulse oximeter 20 shown in FIG. 2. 3 is a functional block diagram showing a functional configuration of an arithmetic processing unit 43. FIG. It is a graph which shows an example of a photoelectric pulse wave waveform. Is a graph showing an example of time-series data of SpO ₂ (SpO ₂ curve). It is a figure which shows typically the detection index of Dip. For some subjects, a single measurement trend graph SpO ₂ based on (sleep total time = about 2.3 hours) 2-wavelength photoelectric pulse wave data obtained by. A period-specific trend graph shown in FIG. 9 is a diagram of a table format showing each seeking the number and ODI values Dip the SpO ₂ curve 63-65. It is a graph showing by extracting Dip continuous generation time period only from the trend graph of SpO ₂ shown in FIG. It is a time chart for demonstrating the extraction algorithm of the Dip continuous generation | occurrence | production time slot | zone in the time slot | zone extraction part 434. FIG. It is a graph for demonstrating the process in the ODI calculation part 436. FIG. 12 is a plan view showing an example of a display mode of a SAS screening result on the display unit 212. FIG. It is a flowchart for demonstrating operation | movement of SAS screening system S1. It is a flowchart which shows the detail of the measurement data analysis process in step S7 of the flowchart of FIG. (A), (b) is a schematic diagram for demonstrating the state in which an apnea symptom arises in a SAS patient.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Measurement means 12 Arithmetic processing means 121 Analysis processing means 122 Dip detection means 123 Time zone extraction means 124 ODI detection means 13 Display means 14 Storage means 20 Pulse oximeter 212 Display part (display means)
221 Light-emitting unit 222 Light-receiving unit 30 Measurement circuit unit 40 Control unit 41 Measurement control unit 42 Recording control unit 43 Operation processing unit 431 Pre-processing unit 432 SpO ₂ data generation unit (analysis processing means)
433 Dip detection unit (Dip detection means)
434 time zone extraction unit (time zone extraction means)
435 determination unit (determination means)
436 ODI calculation unit (ODI detection means)
44 Display control unit (display control means)
S0, S1, S2 SAS screening system

Claims (7)

A measuring means for detecting measurement data relating to blood oxygen saturation of the subject;
Analysis processing means for generating time-series data of blood oxygen saturation by performing predetermined data analysis processing on the measurement data acquired by the measurement means;
Dip detecting means for detecting Dip, which is a predetermined decrease peak of the blood oxygen saturation, from the time series data of the blood oxygen saturation,
A time zone extracting means for extracting, from the time series data, a Dip continuous occurrence time zone in which the Dip is continuously generated under a predetermined condition;
ODI calculation means for obtaining a first ODI value that is a Dip occurrence rate per unit time from the number of Dips that occurred in the Dip continuous occurrence time zone and the time sum of the extracted Dip continuous occurrence time zones;
A sleep apnea syndrome screening system, comprising: display means for displaying the first ODI value.   It is determined whether or not the time sum of the Dip continuous occurrence time zone has a predetermined time length. If the time sum has a predetermined time length, the first ODI value is set in the ODI calculating means. The sleep apnea syndrome screening system according to claim 1, further comprising a determination unit that provides an instruction signal for performing a calculation to be obtained. Further comprising display control means for controlling the display operation of the display means,
The ODI calculating means can obtain a second ODI value that is a Dip occurrence rate per unit time from the total time of the time series data and the total number of Dips detected by the Dip detecting means. ,
The sleep apnea syndrome screening system according to claim 1, wherein the display control means causes the display means to display the first ODI value and / or the second ODI value.   The display control means compares the first ODI value and the second ODI value, and if the second ODI value is smaller than a predetermined value compared to the first ODI value, the display control means 4. The sleep apnea syndrome screening system according to claim 3, wherein the first ODI value is displayed by adding the identification information.   The sleep control according to any one of claims 1 to 4, wherein the display control means causes the display means to display a time sum of the Dip continuous occurrence time zone in addition to the first ODI value. Apnea syndrome screening system. Detecting measurement data relating to blood oxygen saturation of the subject;
Generating blood oxygen saturation time-series data by performing a predetermined data analysis process on the measurement data;
Detecting Dip which is a predetermined decrease peak of the blood oxygen saturation from the time-series data of the blood oxygen saturation;
Extracting, from the time series data, a Dip continuous occurrence time zone in which the Dip is continuously generated under a predetermined condition;
And a step of obtaining an ODI value that is a Dip occurrence rate per unit time from the number of Dips generated in the Dip continuous occurrence time zone and the extracted time sum of the Dip continuous occurrence time zones. Sleep apnea syndrome screening method. In the computer provided in the arithmetic processing means of the sleep apnea syndrome screening system comprising a predetermined arithmetic processing means and display means,
Obtaining measurement data on blood oxygen saturation of the subject;
Generating blood oxygen saturation time-series data by performing a predetermined data analysis process on the measurement data;
Detecting Dip which is a predetermined decrease peak of the blood oxygen saturation from the time-series data of the blood oxygen saturation;
Extracting, from the time series data, a Dip continuous occurrence time zone in which the Dip is continuously generated under a predetermined condition;
Obtaining an ODI value that is a Dip occurrence rate per unit time from the number of Dips that occurred in the Dip continuous occurrence time zone and the time sum of the extracted Dip continuous occurrence time zones;
An operation program for a sleep apnea syndrome screening system, comprising: causing the display means to display the ODI value.

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