Respiratory frequency measuring device

Abstract

Provided is a respiratory rate measurement device provided with: a patient connection unit for acquiring biological information for detecting respiration from a user; a conversion unit for converting the biological information detected by the patient connection unit into an electric signal; a respiratory rate calculation unit for processing the converted electrical signal and calculating a respiratory rate; and a signal output unit that outputs the calculated respiratory rate by means of at least one of voice, screen display, and communication signals. And a respiratory rate calculation unit that calculates respiratory accompanying information including a respiratory interval for each respiration detected on the basis of the electrical signal or an amplitude of a detected respiratory waveform, calculates an index relating to reliability of the calculated respiratory rate on the basis of the respiratory accompanying information, and outputs the index by means of the signal output unit. The respiratory rate measuring device is configured to calculate the respiratory rate and calculate an index related to the stability of the respiration, thereby determining the condition in which the respiration can be stably detected.

Description

TECHNICAL FIELD

[0001] The present application relates to a respiratory rate measuring device or the like for monitoring the respiratory rate of a user. BACKGROUND

[0002] The respiratory rate is, like the body temperature, blood pressure, heart rate, and the like, a most basic value as a vital sign indicating the state of the body, and is particularly an important value in detecting changes in the amount of physical activity, abnormalities in the ventilation function. The heart rate sets an accurate rhythm corresponding to the amount of blood circulation required according to the periodic signal emitted from the sinoatrial node, in contrast to which the state of respiration can be consciously changed. In particular, during wakefulness, it greatly changes or is interrupted regardless of physiological conditions such as the oxygen demand of the body due to physical movement, eating, conversation, and the like, and thus it is extremely difficult to accurately measure the value of the respiratory rate at all times. In most cases, the respiratory rate is measured on site only after a doctor, a nurse, or the like confirms that the patient is in a resting state at the time of a medical examination or the like, and even a measuring device having a function of continuously monitoring the respiratory rate is limited in its application to monitoring during sleep or the like, and the detected value does not always exceed the range of the reference value.

[0003] PRIOR ART DOCUMENTS PATENT LITERATURE Patent Literature 1: WO2020 / 067067 SUMMARY

[0004] PROBLEMS TO BE SOLVED BY THE INVENTION If the state in which the respiration is stable can be detected during the continuous monitoring of the respiratory rate using the respiratory rate measuring device, the long-term change in the physical condition can be detected by comparing the respiratory rate detection values in the stable respiration state according to the monitoring period. Also, there is a possibility that the lowering of the ventilation function caused by chronic lung disease or the like can be detected from the period, frequency, or the like in which the respiration cannot be stably detected.

[0005] As an example of a device that can continuously monitor the respiratory rate and can recognize the resting state, there is a PSG (Polysomnography). The related device is provided with an acceleration sensor for body position determination, an electromyography sensor for sleep stage determination, an electroencephalography sensor, and the like in addition to the airflow sensor for respiration detection, the chest and abdominal belt, and thus can highly accurately analyze the sleep apnea during sleep. On the other hand, since the degree of constraint on the user is high, the analysis of the waveform data requires professional techniques, and thus is not suitable for continuous monitoring over a long period including the daytime and the nighttime.

[0006] In the PSG measurement function, respiratory rate can be measured using only specific sensors such as airflow sensors. However, even in this case, if continuous monitoring is carried out for a long time, the amount of data becomes huge, and analyzing this data and determining whether breathing can be detected normally requires a lot of work.

[0007] Oxygen inhalation therapy was administered to patients with respiratory diseases such as COPD (Chronic Obstructive Pulmonary Disease) and ILD (Interstitial Lung Disease). As disclosed in WO2020 / 067067 (Patent Document 1), a technique was designed to improve the hypoxic state of these patients by embedding a respiratory monitoring device into an oxygen concentrator and using the tube for delivering oxygen to the patient as a unit for acquiring respiratory information. This allows for continuous monitoring of the respiratory status without the need for additional sensors, enabling continuous monitoring of the patient's respiratory status while they inhale oxygen. Future development is expected to include technologies capable of detecting changes in the patient's disease state from continuous respiratory monitoring data.

[0008] However, a drawback of using the tube for oxygen delivery as a respiratory monitoring unit is that noise from the operation of the oxygen concentrator is superimposed on the input to the respiratory monitoring device. Typically, oxygen concentrators use pressure swing adsorption (PSA), employing adsorbent materials such as X-type zeolite that preferentially adsorb nitrogen over oxygen. Nitrogen is adsorbed by supplying pressurized air to an adsorption cylinder enclosed with the adsorbent material, and the adsorbed nitrogen is released by depressurizing the adsorption cylinder. Due to the pressure fluctuations accompanying the adsorption / desorption switching, the flow rate of the delivered oxygen experiences slight periodic variations. While Patent Document 1 discloses techniques for reducing periodically generated noise, the timing of the actions of pressure-driven mechanisms such as check valves and pressure regulating valves in the oxygen concentrator is not entirely periodic and exhibits deviations. Patent Document 1 does not disclose techniques for eliminating non-periodic noise that depends on these operational deviations.

[0009] Furthermore, when the oxygen delivery tube is also used as a respiratory monitoring unit, it is susceptible to noise interference from the patient's body movements, conversations, eating, etc. Besides respiratory monitoring methods within the oxygen delivery tube, another approach is to combine multiple monitoring units, such as a chest and abdominal binder, and compare their data to obtain the most reliable respiratory information. However, this method loses the advantage of being able to monitor breathing without the patient's awareness.

[0010] Therefore, a technique is sought that can distinguish this non-periodic noise from the waveform of breathing and stably acquire the breathing frequency.

[0011] Solution for solving the problem To address the problems described above, the present invention provides a respiratory rate measuring device or an oxygen supply device capable of measuring respiratory rate based on information from a single respiratory sensor that can measure respiratory waveforms, and calculating indicators related to respiratory stability, thereby determining whether a stable respiratory condition can be detected.

[0012] That is, the present invention provides a respiratory rate measuring device comprising: a patient connection unit for acquiring biological information for detecting respiration from a user; a conversion unit for converting the biological information detected by the patient connection unit into an electrical signal; a respiratory rate calculation unit for processing the converted electrical signal and calculating the respiratory rate; and a signal output unit for outputting the calculated respiratory rate through at least one of voice, screen display and communication signals. The respiratory rate measuring device is characterized in that the respiratory rate calculation unit calculates respiratory incidental information including the respiratory interval of each breath detected based on the electrical signal and / or the amplitude of the detected respiratory waveform, calculates an index related to the reliability of the calculated respiratory rate based on the respiratory incidental information, and outputs the index through the signal output unit.

[0013] Furthermore, the present invention provides an oxygen supply device comprising: an oxygen concentrator for concentrating and generating oxygen from the air via a pressure-changing method; a patient connection for supplying concentrated oxygen gas to a user and having a detection unit for detecting changes in gas pressure accompanying the user's breathing; and a respiratory rate measuring unit comprising a conversion unit for converting the pressure change value detected by the patient connection unit into an electrical signal, a respiratory rate calculating unit for processing the converted electrical signal and calculating the respiratory rate, and a signal output unit for outputting the calculated respiratory rate via at least one of voice, video display, and communication signals. The oxygen supply device is characterized in that the respiratory rate measuring unit not only calculates the respiratory rate calculated by the respiratory rate calculating unit, but also calculates respiratory incidental information including the respiratory interval of each breath detected based on the electrical signal and / or the amplitude of the detected respiratory waveform, calculates an index related to the reliability of the calculated respiratory rate based on the respiratory incidental information, and outputs the index through the signal output unit. Related oxygen supply devices can be implemented by integrating the functions of the respiratory rate measuring device of the present invention into a pressure-changing oxygen concentrator and embedding it as a respiratory rate measuring unit.

[0014] The relevant respiratory rate calculation unit is characterized by calculating information representing the variation in the respiratory interval or the amplitude of the respiratory waveform for each detected breath, as an indicator related to the reliability of the respiratory rate. Specifically, a respiratory rate measuring device is provided that: the respiratory rate calculation unit calculates the deviation of the respiratory interval for each detected breath as an indicator related to the reliability of the respiratory rate; if the deviation value exceeds a predetermined threshold, it is determined that the reliability of the calculated respiratory rate value is low, and the determined result is output simultaneously; or a respiratory rate measuring device is provided that: the respiratory rate calculation unit calculates the variance, standard deviation, or interquartile range of the respiratory interval for each breath, or the value obtained by dividing these values ​​by the average or median of the respiratory intervals, as the deviation value of the respiratory interval for each breath; or a respiratory rate measuring device is provided that: the respiratory rate calculation unit outputs the value obtained by averaging the absolute value of the difference between the (i-1)th respiratory interval t(i-1) of the detected continuous breath and the respiratory interval t(i) of the ith breath over multiple i values, or by taking the square root of the squared average of the difference over multiple i values, as the deviation value of the respiratory interval for each breath.

[0015] Furthermore, the present invention provides a respiratory rate measuring device characterized by the following: the respiratory rate calculation unit includes, as an indicator related to the reliability of the respiratory rate, either the value of the amplitude of the detected respiratory waveform or the magnitude of the increase / decrease in amplitude; if the magnitude of the increase / decrease in amplitude or the deviation of amplitude exceeds a threshold, or if the value of amplitude is lower than a threshold, the reliability of the calculated respiratory rate value is determined to be low, and the determined result is output simultaneously.

[0016] Specifically, a respiratory rate measuring device is provided that is characterized by the following: the respiratory rate calculation unit calculates the difference, or the ratio of the average or median amplitude value over a past certain period to the average or median amplitude value over the most recent certain period, as the increase / decrease in amplitude; or a respiratory rate measuring device is provided that is characterized by the following: the respiratory rate calculation unit outputs any one of the variance, standard deviation, and interquartile range of the amplitude value calculated for each detected breath, as the deviation of the amplitude of each detected breath.

[0017] The present invention also provides a respiratory rate measuring device characterized by the following: if the length of the period during which no breathing is detected and / or the frequency of its occurrence is greater than a predetermined value during the respiratory rate calculation, the respiratory rate calculation unit determines that the reliability of the calculated respiratory rate value is low.

[0018] Specifically, a respiratory rate measuring device is provided that is characterized by the following: the respiratory rate calculation unit uses either a period in which the detected respiratory interval is above a certain value or a period in which the amplitude of the respiratory waveform is below a certain value to calculate the period in which no breathing was detected.

[0019] A respiratory rate measuring device is provided that outputs a signal indicating the possibility of apnea when the respiratory rate calculation unit calculates that the length of the period during which no breathing is detected is greater than a predetermined threshold, or when the deviation of the calculated length of the period during which no breathing is detected is greater than a predetermined threshold and the deviation of the amplitude of the respiratory waveform during the period during which breathing is detected is greater than or equal to a predetermined threshold; or a respiratory rate measuring device is provided that outputs a signal indicating the possibility of malfunction in the patient connection when the value of the length of the period during which no breathing is detected is greater than a predetermined threshold that is greater than a threshold used to detect the occurrence of apnea.

[0020] The respiratory rate measuring device of the present invention can be provided as an integrated oxygen supply source for supplying oxygen to the user's mouth or nose, and the patient connection part can also serve as an oxygen supply unit.

[0021] The effects of the invention By using the respiratory rate measuring device of the present invention, users can continuously monitor their breathing over long periods with minimal constraints. It is possible to exclude respiratory disturbances unrelated to physiological oxygen demand caused by conversation, physical movement, etc., from long-term monitoring results, extract values ​​detected at stable breathing intervals, and compare long-term variations to objectively assess changes in physical condition.

[0022] Furthermore, especially during sleep, the likelihood of respiratory distress can be estimated based on the frequency and duration of undetected stable breathing. Additionally, it is possible to use both values ​​related to respiratory amplitude and values ​​related to respiratory frequency as supplementary respiratory information to determine factors of signal instability, such as sleep apnea and detection instability caused by improper installation of the patient connection unit.

[0023] In the respiratory rate measuring device of the present invention, since the stability of respiratory monitoring is determined solely based on the detected respiratory data, for example, when combined with an oxygen concentrator, pressure changes accompanying respiration can be detected via an oxygen supply unit such as an intubation tube used to supply oxygen from the oxygen concentrator to the patient. Furthermore, respiration can be monitored continuously and reliably without installing any items other than the intubation tube necessary for continued patient treatment. This is also a crucial effect of the invention, as patients requiring oxygen often suffer from severe lung diseases such as COPD or restrictive ventilatory disorders, making respiratory monitoring more essential than for other patients. Attached Figure Description

[0024] Figure 1 This is a schematic diagram illustrating an embodiment of the respiratory rate measuring device of the present invention.

[0025] Figure 2 This is a schematic diagram illustrating another embodiment of the respiratory rate measuring device of the present invention.

[0026] Figure 3 This is a schematic diagram illustrating another embodiment of the respiratory rate measuring device of the present invention.

[0027] Figure 4 This is a flowchart of the respiratory rate calculation unit of the respiratory rate measurement unit of the present invention.

[0028] Figure 5 This is another flowchart of the respiratory rate calculation unit of the respiratory rate measurement unit of the present invention.

[0029] Figure 6 It is a comparison of the respiratory rate calculated by the respiratory rate measurement unit of the present invention and the respiratory rate obtained by PSG.

[0030] Figure 7 This is a schematic diagram of the respiratory rate measurement system of the present invention. Detailed Implementation

[0031] Figure 1 The schematic diagram illustrates one embodiment of the respiratory rate measuring device of the present invention.

[0032] The respiratory rate measuring device of the present invention comprises: a patient connection unit 2 for acquiring biological information for detecting respiration from a user; a conversion unit 3 for converting the biological information detected by the patient connection unit into an electrical signal; a respiratory rate calculation unit 4 for processing the converted electrical signal and calculating the respiratory rate; and a signal output unit 5 for outputting the calculated respiratory rate through at least one of voice, screen display and communication signals.

[0033] The patient connection 2, for example, using a nasal cannula, is installed in the nose of the user 1, who is the patient. The other end of the nasal cannula is connected to a conversion unit 3, which transmits pressure changes within the nasal cavity that occur during breathing to the conversion unit 3. The conversion unit 3 can use, for example, a differential pressure sensor that detects the difference between atmospheric pressure and the pressure within the cannula, and can detect pressure with a sensitivity of less than 0.1 Pa. Regarding the combination of the patient connection 2 and the conversion unit 3, in addition to the above-described combination, any unit known as a respiratory detection unit can be used, such as a thermistor-type respiratory sensor that uses a thermistor positioned close to the mouth and nose as the patient connection 2 and a circuit for measuring the resistance of the thermistor as the conversion unit 3, or a combination of a chest and abdomen band with a stretchable conductive material woven into a band provided on the chest and abdomen and a conversion unit 3 that measures the resistance and impedance of the band.

[0034] The patient connection unit 2 detects airflow, pressure, temperature difference between inhalation and exhalation, and expansion and contraction movements of the chest and abdomen, etc., accompanying respiration. These are converted into electrical signals by the conversion unit 3. The resulting respiratory-related signals are input to the respiratory rate calculation unit 4, where the respiratory rate is calculated internally. Methods for calculating respiratory rate include detecting the pressure peak accompanying exhalation / inhalation, detecting the zero-crossing point when switching from exhalation to inhalation or from inhalation to exhalation, detecting the peak value of the autocorrelation value by utilizing the similarity in shape of the respiratory waveforms of each breath, and detecting the frequency through Fourier transform and taking its reciprocal. Any method that can calculate the respiratory interval of each breath can be used.

[0035] In the respiratory rate calculation unit 4, in addition to calculating the respiratory rate, it also calculates an index related to the reliability of the calculated respiratory rate and a determination result of the reliability of the respiratory rate based on the index. Details of the calculation methods for these values ​​and determination results will be described later.

[0036] In the signal output unit 5, the respiratory rate value calculated by the respiratory rate calculation unit 4, reliability-related indicators, and reliability determination results are displayed on the screen via the screen display unit 6 and the communication output unit 7, and simultaneously transmitted to an external server via a communication line. In addition to the methods described above, voice input can also be used as a method for outputting the calculation results. Furthermore, to reduce the burden on the communication line, a built-in storage unit can be incorporated to accumulate data for a certain period and centrally transmit the data to the server at regular intervals.

[0037] like Figure 7As shown, a respiratory rate measurement system can also be constructed as follows: The respiratory rate measuring device of this invention, an external server, and an external terminal are connected via a communication network. The patient's respiratory rate, reliability-related indicators, and reliability determination results measured and calculated by the respiratory rate measuring device are stored on the external server. This allows doctors to view the trend data related to the patient's respiratory rate and its reliability determination results over a specified period via an external terminal installed in a medical institution. In related systems, some or all of the functions of calculating respiratory rate values, reliability-related indicators, and determining reliability, which are handled by the respiratory rate calculation unit 4, can be transferred to the external server.

[0038] Figure 2 The schematic diagram illustrates another embodiment of the respiratory rate measuring device of the present invention. (Compared to...) Figure 1 The difference in the implementation method is that it also includes an oxygen supply source 8, and instead of the patient connection part 2, an oxygen supply unit 9 such as a nasal cannula is installed on the user 1. The other end of the oxygen supply unit 9 is connected to the oxygen supply source 8, and further branches off to connect to the conversion unit 3. In this case, the oxygen supply unit 9 performs both the supply of oxygen to the user 1 and the detection of the pressure accompanying the user 1's breathing. Therefore, the pressure generated by the oxygen flow and the pressure accompanying breathing are superimposed on the conversion unit 3, thus requiring the extraction of the pressure accompanying breathing. As a technique for performing this operation, the technique described in Publication No. WO2020 / 067067 can be used. In this embodiment, the operation of the respiratory rate calculation unit 4 and subsequent operations are similar to... Figure 1 The embodiments are the same.

[0039] Figure 3 The schematic diagram illustrates another embodiment of the respiratory rate measuring device of the present invention. (Compared to...) Figure 2 The difference in implementation is that the oxygen supply unit 9 and a series of subsequent units are housed in a single housing as a respiratory rate measuring device 10 integrated with the oxygen supply source 8. Since the respiratory rate measuring device is typically very small compared to the oxygen supply source 8, it can be integrated with almost no change to the size of the oxygen supply source 8. Furthermore, since the branching of the oxygen supply unit 9 can be done within the integrated housing, it has the advantage of not requiring the tubing connected to the user to branch midway.

[0040] Figure 4 An example of the detailed calculation process inside the respiratory rate calculation unit 4 of the respiratory rate measuring device of the present invention is shown.

[0041] In the respiratory rate calculation unit 4, the biological information detected by the patient connection unit 2 is converted into an electrical signal by the conversion unit 3, the respiratory rate is calculated based on the converted electrical signal, and respiratory incidental information including the respiratory interval of each breath detected or the amplitude of the detected respiratory waveform is calculated. Based on the relevant respiratory incidental information, an index related to the reliability of the calculated respiratory rate is calculated, and the index is output through the signal output unit 5.

[0042] In the first step, a respiratory waveform signal sent from converter 3 is received, and the timing of exhalation or inspiration, or both, is detected from the respiratory waveform signal. As a detection method, the timing of the waveform changing from a positive value to a negative value, or vice versa, can be used as the start time of exhalation / inspiration, or the timing of acquiring the positive and negative peaks of the respiratory waveform signal can be used as the peak of exhalation / inspiration. Alternatively, the relative time difference with the previous exhalation / inspiration can be detected through autocorrelation or the like. Furthermore, the peak values ​​of inspiration / exhalation are simultaneously acquired in this step.

[0043] In the second step, the respiratory interval for each breath is calculated based on the timing of inhalation or exhalation determined in the first step. The respiratory rate is then calculated by dividing the calculated respiratory interval by 60 (in seconds). The respiratory rate can be calculated for each individual breath or over a specific period, such as the average or median over one minute.

[0044] In the third step, the reliability of the calculated respiratory rate is determined based on the timing of inhalation or exhalation and the peak values ​​of inhalation / exhalation as determined in the first step. As for the reliability of respiration, since respiration is usually regular even when unaware of it, the deviation of the respiratory interval determined in the second step can be determined to be within a certain range.

[0045] However, since respiratory rate varies over a long period depending on oxygen demand, if too long a period is set for evaluating the deviation of respiratory interval, the respiratory variations caused by normal changes in oxygen demand will be detected as disturbances in respiratory detection. Furthermore, even if the sensitivity to detection disturbances is reduced to prevent this, the respiratory variations will be averaged and will not follow the actual respiratory variations. Therefore, the deviation of respiratory interval needs to be set as the deviation within a specific period for evaluation.

[0046] Furthermore, regarding the fluctuations after eliminating periodic variations from the oxygen concentrator, although they are non-periodic, they occur at a specific time during the adsorption / desorption switching cycle of the oxygen concentrator. Therefore, if reliability is evaluated over a period much longer than the adsorption / desorption cycle, some noise will be introduced during any evaluation period, making it impossible to obtain highly reliable data. In oxygen concentrators used in home oxygen therapy, the adsorption / desorption switching time is mostly from tens of seconds to several minutes. Therefore, from this perspective, the period used for reliability evaluation should ideally be less than a few minutes. For the same reason, using data over a certain period of time is more advantageous for reliability evaluation than using data based on the number of breaths.

[0047] When awake, breathing is rarely sustained for extended periods due to physical activity, conversation, etc., and it is necessary to detect short-term steady-state states during these intervals. Therefore, it is undesirable to use a long period for evaluating deviations in breathing intervals. Thus, the preferred period for evaluating deviations in breathing intervals is 5 minutes, more preferably 3 minutes or less, since respiratory responses to changes in oxygen demand due to exercise typically last within a few minutes, and the cycles of typical respiratory disturbances such as Cheyne-Stokes respiration and obstructive sleep apnea also last within a few minutes. On the other hand, to calculate deviations, statistical processing of multiple breathing intervals is required; therefore, the shortest period for calculating deviations is approximately 20 seconds corresponding to three breaths, more preferably 30 seconds or more.

[0048] Alternatively, even with changes in respiratory status, the respiratory interval and amplitude between adjacent breaths do not change significantly. Therefore, the average or median difference between respiratory intervals between adjacent breaths can be used as the deviation of the respiratory interval. This method has the advantage that even with significant changes in oxygen demand, if the respiratory rate gradually changes, it can still be considered normal breathing. On the other hand, for single respiratory disturbances caused by physical activity, although it is possible to complete the measurement based on preceding and following data, it may still be detected as disorder, potentially leading to low reliability in interpreting respiratory rate values. Therefore, it is better to differentiate the method based on the purpose of respiratory rate detection.

[0049] Specifically, for an integer i representing a breath, when the time interval between adjacent (i-1)th breaths is set as t(i-1) and the time interval between the i-th breaths is set as t(i), in normal breathing, even with significant changes in breathing frequency, the variation in the breathing interval between adjacent breaths, i.e., the difference between t(i-1) and t(i), will not change significantly. Therefore, the value (mean or median) obtained by statistically processing the absolute value of the difference |t(i)-t(i-1)| over a certain number of breaths or a certain time period becomes larger when noise is detected or breathing is significantly disordered, compared to the state of normal breathing detection. Therefore, a threshold can be set, and if the mean or median of |t(i)-t(i-1)| exceeds the threshold, it can be determined that normal breathing detection is not possible. In the above explanation, the difference in breathing intervals is calculated using absolute values, but square values ​​can also be used instead of absolute values. In this case, it is common to use the square root of the result obtained by calculating the mean or median, but the operation of calculating the square root is not necessarily necessary.

[0050] Similarly, since the depth of breathing is roughly constant in an unconscious state, the deviation in the amplitude of each inhalation and exhalation can be determined. In addition, when the tip of the intubation tube has shifted from the nose or dislodged from the nose, the detectable respiratory pressure value decreases significantly, thus allowing the detection of a decrease or sudden change in amplitude.

[0051] In addition to the methods described above, other methods for calculating the reliability of respiratory rate include comparing the detected pressure waveform with a standard respiratory waveform to calculate the matching degree, and estimating the probability of matching the waveform with a waveform caused by breathing based on specific indicators derived from the waveform, such as waveform sharpness and the ratio of inhalation to exhalation. However, in methods that combine an oxygen supply flow path and a respiratory detection unit, the output of the conversion unit 3 cannot accurately reproduce the respiratory waveform due to factors such as the noise of the oxygen supply airflow and the difference in pressure response to the respiratory airflow when exhaling in the opposite direction to the oxygen supply airflow and when inhaling in the same direction as the airflow. Therefore, in a respiratory rate measuring device integrated with an oxygen concentrator as described in this invention, it is desirable to calculate reliability using a method that does not depend on the respiratory waveform.

[0052] In the fourth step, the reliability of the respiratory rate is determined based on the indicators related to the reliability of the respiratory rate calculated in the third step. For this case, a predetermined threshold is set. If the indicator calculated in the third step is lower than or higher than the threshold, the calculated respiratory rate is deemed to have low reliability, and a signal indicating this is output. Alternatively, multiple indicators can be calculated in the second step, and a determination can be made for each indicator based on the threshold determined for that indicator. For example, if the threshold for the deviation of the respiratory interval is set to A, and the threshold for the decrease in amplitude is set to B, low reliability can also be determined when either of the following conditions is met: (3rd quartile - 1st quartile) / median of the respiratory interval > A, and the amplitude value 10 seconds ago - the most recent amplitude value > B.

[0053] The respiratory rate calculated in the above steps, the reliability-related index values ​​of the respiratory rate, and the reliability determination results can be communicated to the user via communication lines or displayed on the device screen.

[0054] In the respiratory rate calculation unit, if the length and / or frequency of the period during which no breathing is detected during the respiratory rate calculation exceeds a predetermined value, the reliability of the calculated respiratory rate value can be determined to be low. The period during which no breathing is detected can be calculated using either a period in which the detected breathing interval exceeds the range of the normal breathing interval (e.g., 1 second to 10 seconds) or a period in which the amplitude of the breathing waveform is below a certain value.

[0055] If the respiratory rate calculation unit calculates that the length of the period during which no breathing is detected, or the sum of the lengths of the periods during which no breathing is detected within a certain period, is greater than a threshold, and the amplitude of the respiratory waveform during the period during which breathing is detected is greater than a predetermined threshold, there is a possibility that apnea may occur.

[0056] On the other hand, if the length of the period during which no breathing is detected is greater than a threshold predetermined as a value larger than the threshold used to detect the occurrence of apnea, there is a possibility that the patient connection may be improperly installed.

[0057] Figure 5 This illustrates a second example of the calculation flow within the respiratory rate calculation unit 4 of the respiratory rate measuring device of the present invention. Figure 4The first example differs in the following way: the data used to calculate reliability-related indicators is not limited to information obtained from exhalation / inhalation detection results; amplitude values ​​are also directly extracted from the detected respiratory waveform information to calculate the reliability index. As for methods to extract amplitude values ​​from respiratory waveform information, well-known methods such as envelope calculation and variance calculation can be used. In addition to the indicators shown in the first example, the calculation method for reliability-related indicators can also include the magnitude and rate of change of amplitude values ​​over a certain period.

[0058] By using the reliability index calculation method of the present invention, even in situations where the start point of exhalation / inhalation cannot be detected, the amplitude value can be calculated. In particular, even in cases where the amplitude changes significantly when sleep apnea occurs, the reliability index based on amplitude can be appropriately calculated.

[0059] Figure 6 The respiratory rate calculation unit 4 of the respiratory rate measuring device of the present invention is shown. Figure 4 The example of the computational flow shown compares the correct data (obtained by visually counting respiratory rates per minute based on respiratory waveforms acquired through polysomnography and plotting them) used to evaluate deviations in respiratory intervals at a) 20 seconds, b) 1 minute, and c) 5 minutes with the detection values ​​calculated by the respiratory rate measuring device of the present invention. The graphs show the correct data and detection values ​​(excluding data deemed unreliable) when the measurement begins immediately after the subject has performed high-intensity exercise such as muscle strength training, through a resting state, and transitions to a sleep state.

[0060] In the example using a) 20 seconds as the period for evaluating the deviation of the breathing interval, while it accurately tracks the drastic changes in respiratory rate immediately after exercise, the number of breaths used to evaluate the deviation decreases during sleep, increasing the likelihood of incorrect detection. This is considered the lower limit of the period for evaluating the deviation. In the example using b) 1 minute, both breathing immediately after exercise and breathing during sleep can be detected relatively well. In the example using c) 5 minutes, extremely high accuracy can be achieved during sleep; however, in areas with large fluctuations in respiratory rate immediately after exercise, the deviation is large, resulting in low reliability and almost no detection. This is considered the upper limit of the period for evaluating the deviation.

[0061] In cases where the time for bias evaluation is set as intermediate values ​​as described above, d) 30 seconds and e) 3 minutes, there is no significant difference compared to b) 1 minute, and 30 seconds to 3 minutes is considered to be the range that yields optimal results. This result also indicates that using 5 minutes to 20 seconds, more preferably 3 minutes to 30 seconds, as the period for bias evaluation matches the physiological response speed of humans and is considered appropriate.

[0062] Industrial availability The respiratory rate measuring device of the present invention is used as a device capable of evaluating and displaying the reliability of the measured respiratory rate value in medical devices such as patient respiratory detection and respiratory rate display of oxygen supply devices used by patients with respiratory diseases.

[0063] Explanation of symbols 1. User (patient); 2. Patient connection unit; 3. Conversion unit; 4. Respiratory rate calculation unit; 5. Signal output unit; 6. Screen display unit; 7. Communication output unit; 8. Oxygen supply source; 9. Oxygen supply unit; 10. Respiratory rate measurement device integrated with oxygen supply source.

Claims

1. A respiratory rate measuring apparatus comprising: a patient connection portion for acquiring biological information for detecting respiration from a user; a conversion portion for converting the biological information detected by the patient connection portion into an electrical signal; a respiratory rate calculation portion for processing the converted electrical signal and calculating a respiratory rate; and a signal output portion for outputting the calculated respiratory rate by at least one of voice, a screen display, and a communication signal, characterized in that the respiratory rate calculation portion calculates not only the respiratory rate but also respiratory incidental information including a respiratory interval of each respiration detected based on the electrical signal and / or an amplitude of a detected respiratory waveform, calculates an index related to reliability of the calculated respiratory rate based on the respiratory incidental information, and outputs the index through the signal output portion.

2. The respiratory rate measuring apparatus according to claim 1, characterized in that the respiratory rate calculation portion calculates information indicating a variation of the respiratory interval of each respiration detected and / or the amplitude of the respiratory waveform within a certain period of time traced back from a timing at which the respiratory rate is calculated by the respiratory rate calculation portion, as the index related to reliability of the respiratory rate.

3. The respiratory rate measuring apparatus according to claim 2, characterized in that a length of the certain period of time is set to 20 seconds or more and 5 minutes or less.

4. The respiratory rate measuring apparatus according to claim 2, characterized in that a length of the certain period of time is set to 30 seconds or more and 3 minutes or less.

5. The respiratory rate measuring apparatus according to any one of claims 2 to 4, characterized in that the respiratory rate calculation portion calculates a deviation of the respiratory interval of each respiration detected as the index related to reliability of the respiratory rate, determines that reliability of the respiratory rate calculation value is low in a case where a deviation value exceeds a threshold value decided in advance, and simultaneously outputs a result of the determination.

6. The respiratory rate measuring apparatus according to claim 5, characterized in that the respiratory rate calculation portion calculates a variance, a standard deviation, or a quartile range of the respiratory interval of each respiration, or a value obtained by dividing these values by an average value or a median value of the respiratory interval, as the deviation value of the respiratory interval of each respiration.

7. The respiratory rate measuring apparatus according to claim 5, characterized in that the respiratory rate calculation portion outputs a value obtained by averaging absolute values of differences between an (i-1)th respiratory interval t(i-1) of consecutive respiration detected and a respiratory interval t(i) of an i-th respiration in a plurality of i values, or a value obtained by squaring-averaging the differences in a plurality of i and taking a square root, as the deviation value of the respiratory interval of each respiration.

8. The respiratory rate measuring apparatus according to any one of claims 2 to 4, characterized in that ​ ​ ​ ​ ​ ​ ​ The respiratory rate calculation section includes either one of a value of an amplitude of the detected respiratory waveform and an increase / decrease amplitude of the amplitude as an index relating to reliability of the respiratory rate, and determines that the reliability of the respiratory rate calculation value is low and outputs the determined result at the same time in a case where the increase / decrease amplitude of the amplitude or a deviation of the amplitude exceeds a threshold value or a case where the value of the amplitude is lower than a threshold value.

9. The respiratory rate measurement device according to claim 8, characterized in that, The respiratory rate calculation section calculates a difference between or a ratio of an average value or a median value of the amplitude values in a certain period in the past and an average value or a median value of the amplitude values in a certain period that is more recent than the certain period, as the increase / decrease amplitude of the amplitude.

10. The respiratory rate measurement device according to claim 8, characterized in that, The respiratory rate calculation section outputs any one of a variance, a standard deviation, and a quartile range of the amplitude values calculated for each of the detected breaths, as the deviation of the amplitude of each of the detected breaths.

11. The respiratory rate measurement device according to claim 1, characterized in that, The respiratory rate calculation section determines that the reliability of the respiratory rate calculation value is low in a case where a length of a period in which no breath is detected during the respiratory rate calculation period and / or a frequency of occurrence thereof is greater than a value decided in advance.

12. The respiratory rate measurement device according to claim 11, characterized in that, The respiratory rate calculation section calculates the period in which no breath is detected using any one of a period in which a detected respiratory interval exceeds a range decided in advance as a range of a usual respiratory interval and a period in which an amplitude of a respiratory waveform is equal to or less than a certain value.

13. The respiratory rate measurement device according to claim 12, characterized in that, The respiratory rate calculation section outputs a signal indicating a possibility that apnea has occurred in a case where a length of the period in which no breath is detected or a sum of lengths of the periods in which no breath is detected in a certain period is a value greater than a threshold value decided in advance and an amplitude of a respiratory waveform in a period in which a breath is detected is equal to or greater than a threshold value decided in advance.

14. The respiratory rate measurement device according to claim 12, characterized in that, The respiratory rate calculation section outputs a signal indicating a possibility that installation of the patient connection section is poor in a case where a value of the length of the period in which no breath is detected is greater than a threshold value decided in advance as a value greater than a threshold value for detecting occurrence of apnea.

15. An oxygen supply device provided with the respiratory rate measurement device according to any one of claims 1 to 14, characterized in that, provided with an oxygen supply source that supplies oxygen to a user's mouth or nose, the patient connection section serving as an oxygen supply unit.

16. A respiratory rate measurement system, by connecting the respiratory rate measurement device according to claim 1, an external server, and an external terminal via a communication network, storing the respiratory rate of a patient, an index related to the reliability of the respiratory rate, a determination result of the reliability, and the like, which are measured and calculated by the respiratory rate measurement device, in the external server, and setting to be able to view the data related to the respiratory rate of the patient by a doctor via the external terminal provided in a medical institution or the like.

17. An oxygen supply device provided with an oxygen concentration section for generating oxygen in air by concentration through pressure swing, a patient connection section for delivering the oxygen concentrated gas to a user, and a detection unit for detecting a change in gas pressure accompanying the breathing of the user, a respiratory rate measurement section provided with a conversion section for converting the value of the pressure change detected by the patient connection section into an electric signal, a respiratory rate calculation section for processing the converted electric signal and calculating the respiratory rate, and a signal output section for outputting the calculated respiratory rate by at least one or more of a voice, a screen display, and a communication signal, characterized in that the respiratory rate measurement section calculates not only the respiratory rate calculated by the respiratory rate calculation section, but also respiratory incidental information including the respiratory interval of each breath based on the electric signal detected in the breathing and / or the amplitude of the detected respiratory waveform, calculates an index related to the reliability of the calculated respiratory rate based on the respiratory incidental information, and outputs the index through the signal output section. ​

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