Breathing gas supply device and control method thereof

Abstract

[Question] In a breathing-synchronized breathing gas supply device that supplies breathing gas in accordance with the breathing cycle, reduce the effects of false detection of the start of the inhalation phase caused by persistent failure to detect inhalation or false detection due to external interference. [Solution] A pressure sensor and a control unit are provided. The control unit determines the point at which the value of pressure data calculated based on the pressure sensor signal becomes less than the inhalation determination threshold as the inhalation detection point, initiates the supply of breathing gas, and rapidly determines the occurrence of failure to detect inhalation and false detection based on changes in the inhalation detection cycle, automatically optimizing the inhalation detection determination conditions corresponding to the user's current breathing pattern.

Description

Technical Field

[0001] The present invention relates to a breathing-synchronized breathing gas supply device and a control method thereof, wherein the breathing-synchronized breathing gas supply device supplies breathing gas such as concentrated oxygen according to the user's breathing cycle. Background Art

[0002] As a treatment for respiratory diseases such as asthma, emphysema, and chronic bronchitis, oxygen inhalation therapy, in which patients inhale high-concentration oxygen gas to replenish oxygen deficiencies, is commonly performed. Home oxygen inhalation therapy involves the patient, or user, following a doctor's prescription and operating a respiratory gas supply device such as an oxygen concentrator or oxygen cylinder to perform oxygen inhalation therapy at home. Recently, the development of battery-powered portable oxygen concentrators and other devices has expanded the use of respiratory gas supply devices.

[0003] To achieve compactness, lightweightness, and long-term operation, portable respiratory gas supply devices often feature a breath-synchronized on-demand function (Patent Documents 1 and 2). This on-demand function uses a pressure sensor or other device to detect the user's inhalation and, in sync with the breathing cycle, delivers respiratory gas, such as oxygen, only during the inhalation phase, stopping supply during the exhalation phase. Rather than continuously delivering respiratory gas, this pulsed supply, in accordance with the user's breathing cycle, reduces both gas consumption and power consumption.

[0004] Methods for detecting the onset of inspiration using a demand-based function have been devised, such as installing a pressure sensor in the gas supply path to the cannula to detect pressure changes associated with the onset of inspiration. For example, methods have been proposed in which the onset of inspiration is determined when the pressure value detected by the pressure sensor falls below a predetermined pressure threshold, or when the time rate of change (pressure gradient) of the pressure value from the expiratory phase to the inspiratory phase exceeds a predetermined pressure gradient threshold. Patent Document 3 describes a demand-based function that detects respiratory phases that vary depending on activity states such as rest, work, and sleep, and supplies inhalation gas in synchronization with each respiratory cycle.

[0005] Furthermore, a technology has been devised to achieve stable inhalation detection regardless of respiratory status. This technology determines respiratory rate, etc., based on periods of approximately constant, uninterrupted inhalation detection cycles. If the inhalation detection count falls below a certain threshold, shallow breathing is expected, and the onset of inhalation is not correctly detected. Therefore, the inhalation onset determination conditions are relaxed. If the inhalation detection count exceeds a certain threshold, external disturbances other than breathing are expected to be excessively detected, and therefore, the inhalation onset determination conditions are tightened (Patent Document 4).

[0006]

Prior Technical Documents

[0007] [Patent Literature]

[0008] [Patent Document 1] Japanese Patent No. 2656530;

[0009] [Patent Document 2] Japanese Patent Application Publication No. 2004-105230;

[0010] [Patent Document 3] WO2018 / 180848;

[0011] [Patent Document 4] Japanese Patent Application Publication No. 2015-531308. Summary of the Invention

[0012] [Problems to be solved by the invention]

[0013] It is generally known that patients with respiratory diseases receiving oxygen therapy may experience decreased blood oxygen saturation, shortness of breath, or difficulty breathing if oxygen inhalation is interrupted for even a few seconds. Furthermore, the continuous supply of pulses of respiratory gas at times unrelated to inhalation can cause discomfort. Therefore, even when optimizing inhalation determination conditions based on a prolonged inhalation detection cycle due to persistent failure to detect inhalation, or an abnormally short inhalation detection cycle due to persistent detection of external interference, it can take a long time to resume proper inhalation detection, causing the user to experience the aforementioned difficulty breathing or discomfort.

[0014] The present invention has been made in view of such circumstances, and its object is to provide a respiratory gas supply device having an on-demand adjustment function that rapidly determines the occurrence of non-detection and false detection of inhalation based on changes in the inhalation detection cycle, and automatically optimizes the inhalation detection determination conditions to correspond to the user's current breathing pattern.

[0015]

Solutions to Solve the Problem

[0016] The present invention includes the following aspects (1) to (24).

[0017] (1) A first respiratory gas supply device of the present invention is a breathing-synchronized respiratory gas supply device that supplies respiratory gas in accordance with a user's breathing cycle, and is characterized in that the respiratory gas supply device comprises:

[0018] A pressure sensor for measuring the pressure of the gas supply path; and

[0019] A control unit that selects one inhalation determination threshold value from a plurality of predetermined inhalation determination threshold values,

[0020] The control unit determines a point at which a value of pressure data calculated based on a signal from the pressure sensor becomes smaller than a selected inhalation determination threshold as an inhalation detection point, and supplies the breathing gas for a predetermined time based on the inhalation detection point.

[0021] The control unit switches the inhalation determination threshold to an inhalation determination threshold that is larger than the selected inhalation determination threshold when the value of (average of time intervals between the most recent n1 inhalation detection points) divided by (average of time intervals between the most recent n2 inhalation detection points) is greater than X%.

[0022] The control unit switches the inhalation determination threshold to an inhalation determination threshold that is smaller than the selected inhalation determination threshold when a value of (average value of time intervals between the most recent n1 inhalation detection points) divided by (average value of time intervals between the most recent n2 inhalation detection points) is less than Y%.

[0023] (2) In the breathing gas supply device of (1), the number n1 is 2 or more.

[0024] (3) In the breathing gas supply device of (1), it is characterized in that the n2 times is 3 times or more.

[0025] (4) In the respiratory gas supply device according to any one of (1) to (3), the X% is a value greater than 600% and less than 1000%.

[0026] (5) In the respiratory gas supply device according to any one of (1) to (4), the Y% is a value greater than 10% and less than 17%.

[0027] (6) In the respiratory gas supply device of any one of (1) to (5), it is characterized in that when the largest inhalation determination threshold value among the predetermined multiple inhalation determination threshold values is selected, when the value of (the average value of the time intervals between the most recent n1 inhalation detection points) ÷ (the average value of the time intervals between the most recent n2 inhalation detection points) is greater than X%, the control unit switches the supply of the respiratory gas to continuous supply for a certain period of time or pulse supply for a certain period of time.

[0028] (7) The second breathing gas supply device of the present invention is a breathing-synchronized breathing gas supply device that supplies breathing gas in accordance with the user's breathing cycle, and is characterized in that the breathing gas supply device comprises:

[0029] A pressure sensor for measuring the pressure of the gas supply path; and

[0030] A control unit that selects one inhalation determination threshold value from a plurality of predetermined inhalation determination threshold values,

[0031] The control unit determines a point at which a value of pressure data calculated based on a signal from the pressure sensor becomes smaller than a selected inhalation determination threshold as an inhalation detection point, and supplies the breathing gas for a predetermined time based on the inhalation detection point.

[0032] The control unit switches the inhalation determination threshold to a larger inhalation determination threshold than the selected inhalation determination threshold when the total value of the time intervals between the most recent n3 inhalation detection points is longer than the first time.

[0033] The control unit switches the inhalation determination threshold to an inhalation determination threshold that is smaller than the selected inhalation determination threshold when the total value of the time intervals between the most recent n3 inhalation detection points is shorter than the second time.

[0034] (8) In the breathing gas supply device of (7), it is characterized in that the n3 times is 2 times or more.

[0035] (9) In the breathing gas supply device of (7) or (8), the first time is longer than n3×7.5 seconds.

[0036] (10) In the respiratory gas supply device according to any one of (7) to (9), the second time is shorter than n3×1.2 seconds.

[0037] (11) In the respiratory gas supply device of any one of (7) to (10), it is characterized in that when the largest inhalation determination threshold value among the predetermined multiple inhalation determination threshold values is selected, when the total value of the time intervals between the most recent n3 inhalation detection points is longer than the first time, the control unit switches the supply of the respiratory gas to continuous supply for a certain time or pulse supply for a certain period.

[0038] (12) In the respiratory gas supply device according to any one of (1) to (11), the value of the pressure data is a pressure value or a pressure gradient value.

[0039] (13) In the respiratory gas supply device according to any one of (1) to (12), the inhalation determination threshold is a pressure threshold or a pressure gradient threshold.

[0040] (14) In the respiratory gas supply device according to any one of (1) to (13), the inhalation determination threshold comprises at least a first pressure gradient threshold and a second pressure gradient threshold greater than the first pressure gradient threshold,

[0041] The first pressure gradient threshold is greater than or equal to -4.0 Pa / 20 ms and less than or equal to -1.0 Pa / 20 ms.

[0042] The second pressure gradient threshold is greater than or equal to -0.8 Pa / 20 ms and less than or equal to -0.1 Pa / 20 ms.

[0043] (15) In the respiratory gas supply device according to any one of (1) to (13), the inhalation determination threshold includes at least a first pressure threshold and a second pressure threshold greater than the first pressure threshold,

[0044] The first pressure threshold is greater than -10.0 Pa and less than -5.0 Pa.

[0045] The second pressure threshold is greater than or equal to -3.0 Pa and less than or equal to -1.0 Pa.

[0046] (16) The third respiratory gas supply device of the present invention is a breathing-synchronized respiratory gas supply device that supplies respiratory gas in accordance with the user's breathing cycle, and is characterized in that the respiratory gas supply device comprises:

[0047] A pressure sensor for measuring the pressure of the gas supply path; and

[0048] A control unit that selects one inhalation determination threshold value from a plurality of predetermined inhalation determination threshold values,

[0049] The control unit determines a point at which the value of pressure data calculated based on the signal from the pressure sensor becomes smaller than a selected inhalation determination threshold as an inhalation detection point, and supplies the breathing gas for a predetermined time based on the inhalation detection point.

[0050] The intake determination threshold is switched based on the minimum pressure value during the most recent 7.5 seconds.

[0051] (17) In the breathing gas supply device of (16), it is characterized in that

[0052] The control unit switches the inhalation determination threshold to an inhalation determination threshold that is larger than the selected inhalation determination threshold when the minimum value of the pressure values during the most recent 7.5 seconds is greater than the first pressure determination threshold.

[0053] The control unit switches the inhalation determination threshold to an inhalation determination threshold that is smaller than the selected inhalation determination threshold when the minimum value of the pressure values during the most recent 7.5 seconds is smaller than the second pressure determination threshold.

[0054] (18) In the breathing gas supply device of (16) or (17), it is characterized in that the first pressure judgment threshold is greater than or equal to -10 Pa and less than or equal to -5 Pa, and the second pressure judgment threshold is greater than or equal to -100 Pa and less than or equal to -50 Pa.

[0055] (19) In the breathing gas supply device according to any one of (1) to (18), the breathing gas is concentrated oxygen and the breathing gas supply device is an oxygen concentrator.

[0056] (20) The first method for controlling a respiratory gas supply device of the present invention is a method for controlling a respiratory gas supply device that supplies respiratory gas in accordance with a user's respiratory cycle, and is characterized by:

[0057] an inhalation determination threshold selection step, selecting an inhalation determination threshold from a plurality of predetermined inhalation determination thresholds;

[0058] an inhalation detection point detecting step of detecting an inhalation detection point at which a value of pressure data calculated based on a signal from a pressure sensor detecting the respiratory cycle becomes smaller than the inhalation determination threshold value selected in the inhalation determination threshold value selecting step; and

[0059] an inhalation determination threshold switching step of switching the one inhalation determination threshold to any one of the plurality of inhalation determination thresholds based on the time interval between the most recent n1 inhalation detection points;

[0060] In the inhalation determination threshold switching step, when the value of (average of time intervals between the most recent n1 inhalation detection points) divided by (average of time intervals between the most recent n2 inhalation detection points) is greater than X%, the inhalation determination threshold is switched to an inhalation determination threshold that is larger than the selected inhalation determination threshold, and when the value of (average of time intervals between the most recent n1 inhalation detection points) divided by (average of time intervals between the most recent n2 inhalation detection points) is less than Y%, the inhalation determination threshold is switched to an inhalation determination threshold that is smaller than the selected inhalation determination threshold.

[0061] (21) The second method for controlling a respiratory gas supply device of the present invention is a method for controlling a respiratory gas supply device of a breathing-synchronized type that supplies respiratory gas in accordance with a user's breathing cycle, and is characterized by:

[0062] an inhalation determination threshold selection step, selecting an inhalation determination threshold from a plurality of predetermined inhalation determination thresholds;

[0063] an inhalation detection point detecting step of detecting an inhalation detection point at which a value of pressure data calculated based on a signal from a pressure sensor detecting the respiratory cycle becomes smaller than the inhalation determination threshold value selected in the inhalation determination threshold value selecting step; and

[0064] an inhalation determination threshold switching step of switching the one inhalation determination threshold to any one of the plurality of inhalation determination thresholds based on the time intervals between the most recent n3 inhalation detection points;

[0065] In the inhalation determination threshold switching step, when the total value of the time intervals between the most recent n3 inhalation detection points is longer than the first time, the inhalation determination threshold is switched to an inhalation determination threshold that is larger than the selected inhalation determination threshold; and when the total value of the time intervals between the most recent n3 inhalation detection points is shorter than the second time, the inhalation determination threshold is switched to an inhalation determination threshold that is smaller than the selected inhalation determination threshold.

[0066] (22) The third method for controlling a respiratory gas supply device of the present invention is a method for controlling a respiratory gas supply device of a breathing-synchronized type that supplies respiratory gas in accordance with a user's breathing cycle, and is characterized by:

[0067] an inhalation determination threshold selection step, selecting an inhalation determination threshold from a plurality of predetermined inhalation determination thresholds;

[0068] an inhalation detection point detecting step of detecting an inhalation detection point at which a value of pressure data calculated based on a signal from a pressure sensor detecting the respiratory cycle becomes smaller than the inhalation determination threshold value selected in the inhalation determination threshold value selecting step; and

[0069] The inhalation determination threshold switching step switches the one inhalation determination threshold to any one of the plurality of inhalation determination thresholds based on a minimum value of the pressure value during the most recent 7.5 seconds.

[0070] (23) In the control method of the respiratory gas supply device of (22), it is characterized in that, in the inhalation determination threshold switching step, when the minimum value of the pressure value during the most recent 7.5 seconds is greater than the first pressure determination threshold, the inhalation determination threshold is switched to an inhalation determination threshold that is larger than the selected inhalation determination threshold, and when the minimum value of the pressure value during the most recent 7.5 seconds is less than the second pressure threshold, the inhalation determination threshold is switched to an inhalation determination threshold that is smaller than the selected inhalation determination threshold.

[0071] (24) In the control method of any one of (20) to (23) for a breathing gas supply device, it is characterized in that it further includes a step of pulse-supplying the breathing gas for a certain period of time if the inhalation detection point is detected in the inhalation detection point detection step.

[0072] [Effects of the present invention]

[0073] According to the present invention, a respiratory gas supply device can be provided, which has an on-demand adjustment function, in which the respiratory phase is accurately detected, the non-detection and false detection of inhalation are quickly determined based on changes in the inhalation detection cycle, and the judgment conditions for inhalation detection are automatically optimized to correspond to the user's current breathing pattern. BRIEF DESCRIPTION OF THE DRAWINGS

[0074]

Figure 1

[0075]

Figure 2

[0076]

Figure 3

[0077]

Figure 4

[0078]

Figure 5

[0079]

Figure 6

[0080]

Figure 7

[0081]

Figure 8

[0082] Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

[0083] Figure 7 The diagram schematically shows the breathing pattern of a person when awake and the breathing pattern when sleeping. Generally, breathing becomes shallower during sleep, so the breathing pattern during sleep ( Figure 7(b) ) and breathing patterns during wakefulness ( Figure 7 (a)) is smaller than the pressure amplitude, and the pressure gradient at 0Pa from the exhalation phase to the inspiration phase is also smaller. In the present invention, the pressure gradient value is a value calculated as (current pressure value) - (pressure value 20ms ago) using the pressure value calculated based on the signal of the pressure sensor. In addition, in the present invention, the pressure value and pressure gradient value calculated based on the signal of the pressure sensor are sometimes collectively referred to as pressure data. In addition, as shown in FIG. Figure 7 and Figure 8 As can be understood, the pressure gradient value from the expiratory phase to the inspiratory phase of the breathing pattern and the pressure value in the inspiratory phase are always below zero.

[0084] For example, about Figure 7 The breathing pattern of the awake person is determined by setting the pressure gradient threshold (hereinafter sometimes referred to as "threshold A") to -2.0 Pa / 20 ms, and defining the point where the pressure gradient value measured by the pressure sensor becomes smaller than the threshold A (the point where the slope becomes larger) as the inhalation detection point G. This inhalation detection point G is determined to be the start of the inhalation phase. Figure 7 In (a), immediately after the transition from the expiratory phase to the inspiratory phase, the pressure gradient value reaches a maximum gradient of -4.0 Pa / 20 ms and becomes smaller than the threshold value A. Therefore, the start of the inspiratory phase can be detected as the inspiratory detection point G.

[0085] On the other hand, the breathing pattern during sleep is Figure 7 In (b), breathing is shallower and slower than when awake, so even at a maximum gradient pressure gradient value of -1.0 Pa / 20 ms, it rarely falls below threshold A (and rarely becomes larger in terms of slope). Consequently, failure to detect the inhalation detection point G can easily lead to erroneous detection of the start of the inhalation phase. In this case, if threshold A is reset to, for example, -0.2 Pa / 20 ms, the sensitivity increases, allowing detection of the inhalation detection point G even at a maximum gradient pressure gradient value of -1.0 Pa / 20 ms. However, if threshold A is set during wakefulness to match that of sleep, the sensitivity becomes excessively high, and even noise from the pressure sensor caused by vibrations generated when carrying the respiratory gas supply device or slight body movements may be detected as pressure changes due to breathing, frequently leading to erroneous detection of the inhalation detection point G.

[0086] The breathing synchronized breathing gas supply device of the embodiment stores a plurality of inhalation determination thresholds. As the inhalation determination threshold A, in addition to the pressure gradient threshold, a pressure threshold can also be used. Figure 8The breathing pattern during wakefulness is that the pressure threshold value (hereinafter sometimes referred to as "threshold value A") is set to -10Pa, and the point where the pressure value measured by the pressure sensor becomes less than the threshold value A is defined as the inhalation detection point G, and the inhalation detection point G is determined to be the start of the inhalation phase. Figure 8 In (a), the pressure value becomes smaller than the threshold value A immediately after the transition from the exhalation phase to the inspiration phase, so the start of the inspiration phase can be detected as the inspiration detection point G.

[0087] On the other hand, the breathing pattern during sleep is Figure 8 In (b), since breathing is shallower and slower than when awake, the minimum pressure value is -5.0 Pa, making it less likely to fall below threshold value A. Consequently, failure to detect the inhalation detection point G can easily lead to erroneous detection of the start of the inhalation phase. In this case, resetting threshold value A to -1.0 Pa, for example, increases sensitivity, allowing detection of the inhalation detection point G even at a minimum pressure value of -5.0 Pa. However, setting threshold value A during wakefulness to match sleep will result in excessive sensitivity, potentially detecting even pressure sensor noise caused by vibrations generated by carrying the respiratory gas supply device or subtle body movements as pressure changes due to breathing, leading to frequent erroneous detection of the inhalation detection point G.

[0088] Figure 1 This is a diagram showing the main configuration related to the demand-based adjustment function of the respiratory gas supply device. Figure 1 In the figure, solid lines indicate the gas flow path, and dashed lines indicate the path of electrical signals. Respiratory gas supply source 1, such as an oxygen concentrator or oxygen cylinder, supplies concentrated oxygen, or inhalation gas, at a predetermined pressure and concentration. Control valve 6, such as a solenoid valve, opens and closes in response to signals from control unit 5. Gas supplied from respiratory gas supply source 1 is supplied to the user through cannula 2 by opening and closing control valve 6, which is controlled by control unit 5. A pressure sensor 4 is provided on gas supply path 3 connecting control valve 6 and cannula 2.

[0089] The on-demand adjustment function is briefly described. First, pressure sensor 4 constantly measures the pressure in gas supply path 3, which fluctuates due to the user's breathing, and transmits it to control unit 5. Based on the real-time breathing pattern obtained by pressure sensor 4, control unit 5 detects inhalation detection point G, identifies inhalation detection point G as the start of the inhalation phase, opens control valve 6, and, after supplying a constant flow of respiratory gas to cannula 2 for a certain period of time, closes control valve 6. Furthermore, to ensure that nearly all of the supplied oxygen is used for alveolar oxygen exchange, oxygen administered after the first 60% of inspiration typically remains in the dead zone and does not participate in alveolar gas exchange, and given that the patient's respiratory rate is generally around 8 to 48 bpm, it is desirable to complete oxygen supply within approximately 0.24 to 1.2 seconds from detection of inhalation detection point G.

[0090] In parallel with the control of the control valve 6, the control unit 5 determines whether it is necessary to switch the threshold value A used for detecting the inhalation detection point G based on the average value of the time intervals between multiple inhalation detection points G. More specifically, based on the average value of the time intervals between the multiple most recent inhalation detection points G, the control unit 5 selects one of the inhalation determination threshold values suitable for awakening (threshold value A1, threshold value A2, threshold value A3) or the inhalation determination threshold value suitable for sleeping (threshold value A4) to switch the threshold value A.

[0091] The respiratory gas supply device of the embodiment stores a plurality of inhalation determination threshold values. Figure 2 The flowchart shows the process in which the control unit 5 determines whether the threshold value A needs to be switched and switches the threshold value A to the threshold value A1, the threshold value A2, the threshold value A3, or the threshold value A4.

[0092] When the device is activated and the on-demand adjustment function is activated, the control unit 5 sets threshold A to the lowest sensitivity threshold (threshold A1) suitable for awake patients, i.e., the inhalation determination threshold (step S1). When using a pressure gradient threshold as the inhalation determination threshold, measurements and studies of the breathing patterns of several awake HOT patients have shown that the first pressure gradient threshold is preferably set within the range of 4.0 Pa / 20 ms to -1.0 Pa / 20 ms. More preferably, threshold A1 is within the range of -4.0 ± 1.0 Pa / 20 ms, threshold A2 is within the range of -2.0 ± 1.0 Pa / 20 ms, and threshold A3 is within the range of -1.0 ± 0.5 Pa / 20 ms. Furthermore, when using a pressure threshold as the inhalation determination threshold, measurements and studies of the breathing patterns of multiple HOT patients while awake have shown that the first pressure threshold is preferably set within the range of -10.0 Pa to -5.0 Pa, with threshold A1 more preferably within the range of -10.0 ± 2.0 Pa, threshold A2 within the range of -5.0 ± 2.0 Pa, and threshold A3 within the range of -3.0 ± 1.0 Pa. Measurements and studies of the breathing patterns of multiple HOT patients while asleep have shown that, in order to maintain a ratio (detection rate) of the number of inhalation detection points G to the actual number of respirations of 75% or higher, when using a pressure gradient threshold as the inhalation determination threshold, threshold A4 is preferably set within the range of -0.8 Pa / 20 ms to -0.1 Pa / 20 ms, and more preferably within the range of -0.2 ± 0.05 Pa / 20 ms, as the second pressure gradient threshold. Furthermore, when a pressure threshold is used as the intake determination threshold, it is found that the threshold value A4 is preferably -3.0 Pa to -1.0 Pa as the second pressure threshold, and more preferably within the range of -1.0±0.5 Pa.

[0093] When the first pressure gradient threshold (threshold A1, threshold A2, threshold A3) is less than -4.0 Pa / 20 ms, when the first pressure threshold (threshold A1, threshold A2, threshold A3) is less than -10.0 Pa, when the second pressure gradient threshold (threshold A4) is less than -0.8 Pa / 20 ms, or when the second pressure threshold (threshold A4) is less than -3.0 Pa, the sensitivity to the patient's breathing pattern while awake and asleep is insufficient, respectively. Therefore, the detection rate of the inhalation detection point G relative to the actual number of breaths becomes less than 75%, and sufficient breathing gas cannot be supplied to maintain the user's blood oxygen saturation (SpO2) at or above 90%, which is a generally appropriate value.

[0094] Furthermore, when the first pressure gradient thresholds (thresholds A1, A2, and A3) are greater than -1.0 Pa / 20 ms, greater than -5.0 Pa, greater than -0.1 Pa / 20 ms, or greater than -1.0 Pa, the detection rate of the inhalation detection point G relative to the actual number of breaths becomes 130% or higher. This increases the rate at which noise from the pressure sensor 4 is mistakenly detected as the inhalation detection point G, preventing the supply of breathing gas synchronized with the start of the inhalation phase. This causes discomfort to the user and increases breathing gas consumption.

[0095] The control unit 5 detects the inhalation detection point G based on the threshold value A1 set in step S1 and the pressure gradient value or pressure value calculated from the signal of the pressure sensor 4, and starts pulse supply of the respiratory gas in synchronization with the start of the inhalation phase.

[0096] Next, the control unit 5 uses the latest value data for the time interval between the most recent inhalation detection points G and the average value data for the time intervals between the most recent inhalation detection points G to determine whether it is necessary to switch from threshold value A1 to threshold value A2, from threshold value A2 to threshold value A3, or from threshold value A3 to threshold value A4 (steps S2, S5, and S8). More specifically, if the value (average value of the time intervals between the most recent n1 inhalation detection points G since the measurement) divided by the value (average value of the time intervals between the most recent n2 inhalation detection points G) exceeds X%, the control unit 5 determines that breathing is not being correctly detected and switches the inhalation determination threshold to a more sensitive threshold. In this case, n1 can be any value representing the number of inhalation detection points G detected, including the most recently detected inhalation detection point G, of two or more times. For example, in the case of "the time interval between the two most recently detected inhalation detection points G," this refers to the time interval between the two most recently detected inhalation detection points G. n2 can be any value representing the number of inhalation detection points G detected, including the most recently detected inhalation detection point G, of three or more times, with n1 < n2. In order to optimize the sensitivity earlier, it is desirable that n1 be set to 2 times and n2 be set to a value of 5 times or more and 10 times or less.

[0097] Regarding determining whether to switch the inhalation determination threshold, it is known that the human respiratory rate generally ranges from approximately 8 to 48 bpm, and that the respiratory cycle varies up to approximately 600% as the patient transitions from exertion (maximum 48 bpm) to rest (minimum 8 bpm). Therefore, to avoid unnecessary switching to a higher sensitivity threshold despite accurate respiration detection, it is desirable to set X% to a value greater than 600%. Furthermore, to optimize sensitivity more quickly, it is desirable to set X% to less than 1000%. If the value of (average time intervals between the most recent n1 inhalation detection points G) divided by (average time intervals between the most recent n2 inhalation detection points G) exceeds X%, there is a high probability that the inhalation detection point G cannot be accurately detected at the current threshold A (threshold A1, A2, or A3). Therefore, when (average of the time intervals between the most recent n1 inhalation detection points G) ÷ (average of the time intervals between the most recent n2 inhalation detection points G) becomes greater than X%, the control unit 5 switches the threshold value A to an inhalation determination threshold value with a higher sensitivity by one level (steps S3, S6, and S9).

[0098] When the inhalation determination threshold A is switched to a more sensitive inhalation determination threshold, the control unit 5 detects the point where the pressure gradient value or pressure value becomes less than the switched, more sensitive inhalation determination threshold based on the breathing pattern measured by the pressure sensor 4, and defines this as the inhalation detection point G. In addition, the control unit 5 pulse-supplies respiratory gas. For example, by switching the inhalation determination threshold A to the more sensitive inhalation determination threshold A4, the start of the inhalation phase during sleep, which is often undetectable at thresholds A1 to A3, can be detected as the inhalation detection point G.

[0099] When selecting threshold A2, A3, or A4, the most recent value of the time interval between the most recent inhalation detection points G and the average value of the time intervals between the most recent inhalation detection points G are used to determine whether a switch from threshold A4 to threshold A3, from threshold A3 to threshold A2, or from threshold A2 to threshold A1 is necessary (steps S4, S7, and S10). More specifically, if the value (average of the time intervals between the most recent n1 inhalation detection points G since the start of measurement) divided by the value (average of the time intervals between the most recent n2 inhalation detection points G) is less than Y%, it is determined that external disturbances such as body movement have been falsely detected, and the inhalation determination threshold is switched to a less sensitive threshold. As previously mentioned, n1 can be set to any number of inhalation detection points G detected, including the most recently detected inhalation detection point G, from two or more times, and n2 can be set to any number of inhalation detection points G detected, including the most recently detected inhalation detection point G, with n1 < n2. Furthermore, to optimize sensitivity more quickly, it is desirable to set n1 to 2 and n2 to 5 or more and 10 or less. As mentioned above, the human respiratory rate ranges from approximately 8 to 48 bpm. Therefore, as the human respiratory cycle changes from a resting state (minimum 8 bpm) to an exertion state (maximum 48 bpm), it can be seen that the respiratory cycle changes by a maximum of approximately 17%. Therefore, to avoid unnecessary switching to a lower sensitivity threshold A despite accurate respiration detection, it is desirable to set Y% to less than 17%. Furthermore, to optimize sensitivity more quickly, it is desirable to set Y% to greater than 10%. If the value of (average time intervals between the most recent n1 inhalation detection points G) divided by (average time intervals between the most recent n2 inhalation detection points G) falls below Y%, the sensitivity is too high when detecting inhalation detection points G using the current threshold A (threshold A2, A3, or A4), resulting in a high probability that noise will be mistakenly detected as inhalation detection points G. Therefore, when (average of the time intervals between the most recent n1 inhalation detection points G) ÷ (average of the time intervals between the most recent n2 inhalation detection points G) becomes less than Y%, the control unit 5 switches the threshold value A to an inhalation determination threshold value with one level lower sensitivity (steps S1, S3, and S6).

[0100] In this way, the control unit 5 switches the inhalation determination threshold value based on the latest value data of the time interval between the most recent inhalation detection points G and the average value data of the time intervals between the most recent multiple inhalation detection points G, thereby controlling the on-demand adjustment function according to the user's condition. As a result, it is possible to accurately detect the start of the inhalation phase and supply breathing gas synchronized with the respiratory cycle.

[0101] Furthermore, the inhalation determination threshold can be switched using the total time intervals between the most recent inhalation detection points G. More specifically, if the total time intervals between the most recent n3 inhalation detection points G are longer than a first time (tsumup), it is determined that breathing has not been correctly detected, and the inhalation determination threshold is switched to a more sensitive threshold. Conversely, if the total time intervals between the most recent n3 inhalation detection points G are shorter than a second time (tsumdown), it is determined that external disturbances such as body movement have been erroneously detected, and the inhalation determination threshold is switched to a less sensitive threshold. In this case, n3 can be set to any number of inhalation detection points G detections, two or more, including the most recently detected inhalation detection point G. To optimize sensitivity more quickly, n3 is preferably set to a value of 5 or more and 10 or less. Furthermore, considering that the human respiratory rate is generally around 8 to 48 bpm, to avoid unnecessary switching of the inhalation determination threshold despite accurate breathing detection, it is desirable to set tsumup to be longer than n3 × 7.5 seconds and tsumdown to be shorter than n3 × 1.2 seconds. Furthermore, 7.5 seconds corresponds to the breathing interval at 8 bpm, and 1.2 seconds to the breathing interval at 48 bpm.

[0102] In addition, the intake determination threshold can also be switched based on the minimum pressure value during the last 7.5 seconds ( Figure 3 ; Steps S12, S15, and S18). More specifically, if the minimum pressure value during the most recent 7.5 seconds is greater than the first pressure determination threshold P1, it is determined that the respiratory pressure is extremely weak, making accurate inhalation detection difficult, and the inhalation determination threshold is switched to a more sensitive threshold (Steps S13, S16, and S19). Conversely, if the minimum pressure value during the most recent 7.5 seconds is less than the second pressure determination threshold P2, it is determined that excessive respiratory pressure is likely to cause false detection due to physical movement, such as during exertion, and the inhalation determination threshold is switched to a less sensitive threshold (Steps S11, S13, and S16). In this case, based on measurements and studies of the respiratory patterns of multiple HOT patients during wakefulness and sleep, it is desirable that the first pressure determination threshold P1 be between -10 Pa and -5 Pa, and the second pressure determination threshold P2 be between -100 Pa and -50 Pa.

[0103] In the respiratory gas supply device of the embodiment, the user can also manually switch the threshold value by sending a sensitivity switching signal from the user interface 7 to the control unit 5 . Figure 4 This is an example of a flow in which the sensitivity can be switched by a manual operation of the user.

[0104] When the device is started and the on-demand adjustment function is working, the control unit 5 sets the threshold value A to the threshold value A1 (step S21). When the user presses the sensitivity increase button of the user interface 7 (step S22), the process proceeds to step S24, and the threshold value A1 is switched to the threshold value A2. In the case where the threshold value A is set to A2 or A3 (steps S24 and S29), when the sensitivity increase button is pressed (steps S25 and S30), the process proceeds to step S29 and step S34, and the threshold value A is switched to A3 and A4, respectively. In addition, when the breathing gas supply device is controlled by the threshold value A2, when the user presses the sensitivity reduction button (step S26), the process proceeds to step S21, and the process switches to the threshold value A1. In the case where the threshold value A is set to A3 or A4 (steps S29 and S34), when the sensitivity reduction button is pressed (steps S31 and S35), the process proceeds to step S24 and step S29, and the threshold value A is switched to A2 and A3, respectively. In Figure 4 In the example shown in FIG5 , the user's operation of the sensitivity switching button takes precedence over the control unit 5's determination of whether the pressure gradient threshold is switched based on the (average of the time intervals between the most recent n1 inhalation detection points G) divided by the (average of the time intervals between the most recent n2 inhalation detection points G) being greater than X%.

[0105] Figure 5 This is an example of a safety function that provides continuous supply of breathing gas for approximately 90 seconds regardless of the breathing phase, in addition to pulse supply of breathing gas synchronized with the breathing phase. Figure 2 The same steps as steps S1 to 10 are used. If, in step S50, the value of (the average time intervals between the n1 most recent inhalation detection points G) divided by (the average time intervals between the n2 most recent inhalation detection points G) is greater than Y%, then, in step S51, a check is performed to determine whether the value of (the average time intervals between the n1 most recent inhalation detection points G) divided by (the average time intervals between the n2 most recent inhalation detection points G) is greater than X%, thereby confirming whether the minimum number of respirations can be detected.

[0106] As mentioned above, since the human respiratory rate is generally around 8 to 48 bpm, if, for example, the ratio (average of the time intervals between the most recent n1 inhalation detection points G) ÷ (average of the time intervals between the most recent n2 inhalation detection points G) exceeds 600% (equivalent to 8 bpm), there is a high possibility that the breathing gas is not being supplied sufficiently due to the long intervals between the inhalation detection points G, even though control is being performed using the highly sensitive threshold A4. Therefore, the control unit 5 switches the breathing gas supply method to continuous supply (automatic continuous flow) (step S52). Figure 1During the continuous supply of breathing gas, control valve 6 remains open, and pressure sensor 4 outputs the breathing gas pressure as the detection pressure. Therefore, during this period, it is impossible to detect pressure fluctuations associated with breathing. Therefore, it is necessary to periodically stop the continuous supply of breathing gas to confirm whether the user's breathing has returned to a sufficient intensity for detection. Therefore, after a certain period of time has passed since the start of the automatic continuous flow supply, control unit 5 returns threshold value A to A4 and resumes detection of the inhalation detection point G (step S55). Based on the inventors' research, which involved measuring and studying the breathing patterns of multiple HOT patients during sleep, the automatic continuous flow supply time was set to 10 to 120 seconds. This increases the likelihood that breathing gas will be inhaled for at least 75% of the total breathing time, with approximately 90 seconds being more preferred.

[0107] Figure 6 This is an example of a safety function that provides a pulse supply of breathing gas at a fixed period regardless of the respiratory phase, in addition to the pulse supply of breathing gas synchronized with the respiratory phase. Figure 5 Steps S41 to S51 are the same.

[0108] The control unit 5 replaces the supply automatic continuous flow ( Figure 5 In step S52, the breathing gas supply method is switched to pulsed supply (auto-pulse) at a fixed cycle (e.g., 50 bpm) (step S72). During this auto-pulse operation, the inhalation detection point G is continuously detected using threshold value A4. If the inhalation detection point G is detected again, the control unit 5 cancels the auto-pulse supply (step S75).

[0109] Furthermore, in step S51 or step S71, if the value of (average of the time intervals between the most recent n1 inhalation detection points G) divided by (average of the time intervals between the most recent n2 inhalation detection points G) is set to 1000% or greater, inhalation detection points G will become virtually impossible to detect, delaying the automatic continuous flow or automatic pulse supply. This will result in insufficient respiratory gas supply to the sleeping user and reduced therapeutic efficacy of the respiratory gas supply device. Therefore, it is desirable to set X% to a value greater than 600% and less than 1000%. Furthermore, if the conditions for switching to automatic continuous flow or automatic pulse (step S51 or step S71) are met five times within 30 minutes (step S53 or step S73), it is determined that there is a high probability of some abnormality occurring in the user or the respiratory gas supply device, and an alarm is sounded (step S54 or step S74).

[0110] exist Figure 5 、 Figure 6In the process, even if the inhalation detection point G is almost impossible to detect and the breathing gas cannot be fully supplied using the on-demand adjustment function, the risk of the user feeling difficulty in breathing is reduced because the breathing gas is automatically supplied through automatic continuous flow or automatic pulse supply.

[0111] In the above description, as an example of the embodiment, the number of levels of the switchable intake determination threshold is set to four. However, the intake determination threshold can be set to any number of levels within the range of the above-mentioned switching method.

[0112] While preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims.

[0113] Industrial Applicability

[0114] According to the present invention, a respiratory gas supply device can be provided, which has an on-demand adjustment function. In this on-demand adjustment function, the control unit of the respiratory gas supply device switches the inhalation determination threshold for detecting the start of the inhalation phase according to the user's state, so that the respiratory phase is accurately detected, the non-detection and occurrence of false detection of inhalation are quickly determined based on changes in the inhalation detection cycle, and the inhalation detection determination conditions are automatically optimized to correspond to the user's current breathing pattern.

[0115]

Number Description

[0116] 1 Breathing gas supply source

[0117] 2 sleeves

[0118] 3 Gas supply path

[0119] 4 Pressure sensor

[0120] 5. Control Unit

[0121] 6 Control valve

[0122] 7 User Interface

[0123] 8 Buzzer

Claims

1. A breathing gas supply device, which is a breathing-synchronized breathing gas supply device that supplies breathing gas in accordance with the user's breathing cycle, characterized in that: The breathing gas supply device comprises: A pressure sensor for measuring the pressure of the gas supply path; and A control unit that selects one inhalation determination threshold value from a plurality of predetermined inhalation determination threshold values, The control unit determines a point at which a value of pressure data calculated based on a signal from the pressure sensor becomes smaller than a selected inhalation determination threshold as an inhalation detection point, and supplies the breathing gas for a predetermined time based on the inhalation detection point. The value of the pressure data is a pressure value or a pressure gradient value, The inhalation determination threshold is a pressure threshold or a pressure gradient threshold, The pressure thresholds serving as the inhalation determination thresholds include at least a first pressure threshold and a second pressure threshold that is greater than the first pressure threshold. The first pressure threshold is greater than -10.0 Pa and less than -5.0 Pa. The second pressure threshold is greater than or equal to -3.0 Pa and less than or equal to -1.0 Pa. The pressure gradient thresholds serving as the inhalation determination thresholds include at least a first pressure gradient threshold and a second pressure gradient threshold that is greater than the first pressure gradient threshold. The first pressure gradient threshold is greater than or equal to -4.0 Pa / 20 ms and less than or equal to -1.0 Pa / 20 ms. The second pressure gradient threshold is greater than or equal to -0.8 Pa / 20 ms and less than or equal to -0.1 Pa / 20 ms. The control unit switches the inhalation determination threshold to an inhalation determination threshold that is larger than the selected inhalation determination threshold when the value of (average of time intervals between the most recent n1 inhalation detection points) divided by (average of time intervals between the most recent n2 inhalation detection points) is greater than X%. The control unit switches the inhalation determination threshold to an inhalation determination threshold that is smaller than the selected inhalation determination threshold when the value of (average of time intervals between the most recent n1 inhalation detection points) divided by (average of time intervals between the most recent n2 inhalation detection points) is less than Y%. The n1 times is 2 or more times, The n2 times is 3 times or more, n1<n2, The X% is a value greater than 600% and less than 1000%, The Y% is a value greater than 10% and less than 17%.

2. The breathing gas supply device according to claim 1, wherein When the largest inhalation determination threshold value among the predetermined plurality of inhalation determination threshold values is selected, the control unit switches the supply of the breathing gas to continuous supply for a predetermined period or pulsed supply for a predetermined period if the value of (average value of time intervals between the most recent n1 inhalation detection points) ÷ (average value of time intervals between the most recent n2 inhalation detection points) is greater than X%.

3. A breathing gas supply device, which is a breathing-synchronized breathing gas supply device that supplies breathing gas in accordance with the user's breathing cycle, characterized in that: The breathing gas supply device comprises: A pressure sensor for measuring the pressure of the gas supply path; and A control unit that selects one inhalation determination threshold value from a plurality of predetermined inhalation determination threshold values, The control unit determines a point at which a value of pressure data calculated based on a signal from the pressure sensor becomes smaller than a selected inhalation determination threshold as an inhalation detection point, and supplies the breathing gas for a predetermined time based on the inhalation detection point. The value of the pressure data is a pressure value or a pressure gradient value, The inhalation determination threshold is a pressure threshold or a pressure gradient threshold, The pressure thresholds serving as the inhalation determination thresholds include at least a first pressure threshold and a second pressure threshold that is greater than the first pressure threshold. The first pressure threshold is greater than -10.0 Pa and less than -5.0 Pa. The second pressure threshold is greater than or equal to -3.0 Pa and less than or equal to -1.0 Pa. The pressure gradient thresholds serving as the inhalation determination thresholds include at least a first pressure gradient threshold and a second pressure gradient threshold that is greater than the first pressure gradient threshold. The first pressure gradient threshold is greater than or equal to -4.0 Pa / 20 ms and less than or equal to -1.0 Pa / 20 ms. The second pressure gradient threshold is greater than or equal to -0.8 Pa / 20 ms and less than or equal to -0.1 Pa / 20 ms. The control unit switches the inhalation determination threshold to a larger inhalation determination threshold than the selected inhalation determination threshold when the total value of the time intervals between the most recent n3 inhalation detection points is longer than the first time. The control unit switches the inhalation determination threshold to an inhalation determination threshold that is smaller than the selected inhalation determination threshold when the total value of the time intervals between the most recent n3 inhalation detection points is shorter than the second time. The first time is a time longer than the n3×7.5 seconds, The second time is less than the time of n3×1.2 seconds, The n3 times is 2 times or more.

4. The breathing gas supply device according to claim 3, wherein When the largest inhalation determination threshold value among the predetermined plurality of inhalation determination threshold values is selected, the control unit switches the supply of the breathing gas to continuous supply for a predetermined time or pulsed supply for a predetermined period if the total time intervals between the most recent n3 inhalation detection points are longer than a first time.

5. The breathing gas supply device according to any one of claims 1 to 4, wherein: The breathing gas is concentrated oxygen, and the breathing gas supply device is an oxygen concentrator.

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