Respiration detector and cannula

Abstract

To more accurately detect a respiratory state of a patient by more accurately detecting pressure fluctuation by the expiration and inspiration of the patient in a respiration detector.SOLUTION: In a respiration detector of the present invention, a gas supply source 1, a nozzle part 6, and a respiration detection part 2 are arranged in series in the order of description in the upstream and downstream directions through a feed passage 7 and a connection passage 8 of a cannula 3. A first throttle part 21 is formed in a main passage part 16 of the connection passage 8 of the cannula 3, and a second throttle part 22 is formed in one branch passage part 17 of two branch passage parts 17 and 18 of the connection passage 8.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a respiration detection device for detecting the respiratory state of a patient with a respiratory disease, and a cannula constituting the respiration detection device. [Background technology]

[0002] It is well known that oxygen therapy is performed on patients with respiratory diseases by supplying oxygen from an oxygen tank. Furthermore, monitoring the respiratory status of the patient during such oxygen therapy, such as the number of breaths and breathing pattern, is also a well-known technique. Examples of known conventional devices for monitoring such respiratory status include those disclosed in Patent Documents 1 and 2.

[0003] In the breath detection device of Patent Document 1, oxygen generated in oxygen concentrator 110 is supplied to nasal cannula main body 100 via an oxygen supply path consisting of buffer tank 120, cushion tank 140, and cord 201 (see FIG. 5 of Patent Document 1). Breath detector 151 detects the patient's breathing state based on the differential pressure between two points on the oxygen supply path that sandwich cushion tank 140. Specifically, solenoid valve 130 is disposed in the flow path between buffer tank 120 and cushion tank 140, and a branch flow path leading to breath detector 151 is connected to solenoid valve 130. In addition, a branch flow path leading to breath detector 151 is also connected downstream of cushion tank 140. Breath detector 151 detects the patient's breathing state based on the differential pressure between the two branch flow paths.

[0004] In the respiration detection device of Patent Document 2, oxygen generated in a concentrator 1 is supplied to a nasal cannula 3 via an oxygen supply path consisting of a conduit means 2 (see FIG. 1 of Patent Document 2). An open valve 40 is disposed midway through the conduit means 2, and a flow path leading to a pressure fluctuation detection means 6 is connected to this open valve 40. This flow path branches into a first flow path that leads to the pressure fluctuation detection means 6 via a passage restriction means 4 and a tank, and a second flow path (conduit 41) that is directly connected from the open valve 40 to the pressure fluctuation detection means 6, and the pressure fluctuation detection means 6 detects the respiratory state of the patient from the differential pressure between the first flow path and the second flow path. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 1-274027 [Patent Document 2] Japanese Patent Application Publication No. 6-190045 Summary of the Invention [Problem to be solved by the invention]

[0006] In the conventional breath detection devices described in Patent Documents 1 and 2, a branch path is formed on an oxygen supply path leading from a gas supply source (oxygen concentrator, concentrator) to the main body of a cannula (nasal cannula), and a breath detection unit (breath detector, pressure fluctuation detection means) detects the patient's breathing condition from the differential pressure in this branch path. Therefore, it is inevitable that the breathing gas (oxygen) delivered from the gas supply source will enter the branch path and change the pressure within the branch path, making it difficult to accurately capture pressure fluctuations due to the patient's exhalation and inhalation and accurately detect the patient's breathing condition. The breath detection devices described in Patent Documents 1 and 2 detect fluctuations in the pressure caused by the breathing gas (oxygen) delivered from the gas supply source flowing into the branch path, which are influenced by the patient's exhalation and inhalation. Therefore, they indirectly detect the patient's breathing condition and are not configured to directly capture pressure fluctuations due to the patient's exhalation and inhalation, resulting in poor detection accuracy. Furthermore, in configurations such as those of the breathing detection devices of Patent Documents 1 and 2, even if the cannula is removed from the patient's nose, the breathing detection unit may only detect pressure fluctuations resulting from the breathing gas delivered from the gas supply source and detect this as the patient's breathing state, which also makes it difficult to accurately detect the patient's breathing state.

[0007] An object of the present invention is to provide a respiration detection device that can more accurately detect pressure fluctuations caused by a patient's inhalation and exhalation, and more accurately detect the patient's respiratory condition, and a cannula that constitutes the respiration detection device. [Means for solving the problem]

[0008] The breath detection device of the present invention comprises a gas supply source 1 that supplies breathable gas, a breath detection unit 2 equipped with a differential pressure sensor 25 that detects pressure changes during exhalation and inhalation, and a cannula 3 disposed between the gas supply source 1 and the breath detection unit 2. The cannula 3 has a gas supply opening 10 and is attached to a human face 5, a supply passage 7 that supplies breathable gas supplied from the gas supply source 1 toward the nozzle 6, and a connecting passage 8 that connects the nozzle 6 to the breath detection unit 2. The connecting passage 8 comprises a main passage 16 connected to the nozzle 6 and two branch passages 17 and 18 branched from the main passage 16 and connected at their downstream ends to the breath detection unit 2. A first throttle section 21 is formed in the main passage 16, and one of the two branch passages 17 and 18 is a throttled flow path 17 equipped with a second throttle section 22, and the other branch passage is a communicating flow path 18 without a throttle section. When the gas supply source 1 is defined as the upstream side and the breathing detection unit 2 as the downstream side, the gas supply source 1, nozzle unit 6, and breathing detection unit 2 are arranged in series in the upstream-downstream direction in the order listed, via the supply passage 7 and connection passage 8.

[0009] The flow path area of ​​the first throttle portion 21 formed in the main passage portion 16 is set to be larger than the flow path area of ​​the second throttle portion 22 formed in the throttle flow path 17.

[0010] The present invention relates to a cannula arranged between a gas supply source 1 that generates respiratory gas and a respiration detection unit 2 that includes a differential pressure sensor 25 that detects pressure changes during exhalation and inhalation. The cannula has a nozzle portion 6 that has a gas supply opening 10 and is attached to a human face portion 5, a supply passage 7 that supplies respiratory gas supplied from the gas supply source 1 toward the nozzle portion 6, and a connection passage 8 that connects the nozzle portion 6 to the respiration detection unit 2. The connection passage 8 has a main passage portion 16 connected to the nozzle portion 6 and two branch passage portions 17 and 18 that branch off from the main passage portion 16 and have downstream ends connected to the respiration detection unit 2. The main passage portion 16 is characterized by having a first throttle portion 21 formed in it, and a second throttle portion 22 formed in one of the branch passage portions 17 and 18.

[0011] The flow passage area of ​​the first throttle portion 21 formed in the main passage portion 16 is set to be larger than the flow passage area of ​​the second throttle portion 22 formed in the branch passage portions 17 and 18. [Effects of the Invention]

[0012] The breathing detection device of the present invention has a gas supply source 1, a nozzle 6, and a breathing detection unit 2 arranged in series in the upstream-downstream direction via a supply passage 7 and a connecting passage 8, and a first throttle section 21 formed in the main passage 16. With this configuration, breathing gas supplied from the gas supply source 1 is sent to the nozzle 6 through the supply passage 7 constituting the cannula 3, and most of it is inhaled by the patient and used for breathing. Meanwhile, some of the breathing gas that passes through the nozzle 6 (hereinafter referred to as "passing gas") passes through the connecting passage 8 toward the downstream breathing detection unit 2, but the first throttle section 21 formed in the main passage 16 restricts the passing gas from flowing smoothly into the branch passages 17 and 18. Thus, according to the present invention, the first restriction portion 21 can restrict the smooth inflow of the passing gas into the branch passages 17 and 18, thereby preventing large fluctuations in the pressure in the branch passages 17 and 18 due to the inflow of the passing gas and minimizing the effect of the respiratory gas (passing gas) on pressure changes associated with the patient's inhalation and exhalation in the branch passages 17 and 18. Furthermore, when the respiration detection unit 2 is located downstream of the nozzle 6 as in the present invention, the air flow in the nozzle 6 associated with the patient's inhalation and exhalation is directly transmitted to the branch passages 17 and 18, and the patient's respiratory condition can be detected by detecting these pressure changes in the branch passages 17 and 18 with the respiration detection unit 2. Therefore, the patient's respiratory condition can be detected more accurately by capturing direct pressure changes caused by the patient's inhalation and exhalation. Furthermore, according to the present invention, when the nozzle portion 6 of the cannula 3 is detached from the facial portion 5, there is almost no change in pressure in the branch passages 17 and 18, and by detecting this pressure state (a state in which no pressure change occurs) with the breathing detection unit 2, it is possible to detect that the nozzle portion 6 has been detached from the facial portion 5. As described above, according to the present invention, pressure fluctuations due to the patient's inhalation and exhalation can be detected more accurately, and therefore the patient's respiratory state can be detected more accurately.

[0013] As described above, the provision of the first throttle section 21 in the main passage 16 can restrict the smooth flow of breathing gas (passing gas) into the branch passages 17 and 18. However, if pressure fluctuations do not occur, particularly in the branch passages 17 and 18, when the patient exhales or inhales, it will be impossible to accurately detect pressure fluctuations due to the patient's inhalation and exhalation. In other words, if the flow path area of ​​the first throttle section 21 in the main passage 16 is extremely small, pressure fluctuations may not occur in the branch passages 17 and 18. On the other hand, the second throttle section 22 formed in the branch passage (throttled flow path) 17 generates a pressure difference with the other branch passage (communicating flow path) 18. Therefore, if the flow path cross-sectional area of ​​the second throttle section 22 is large, no pressure difference will occur between the two branch passages (throttled flow path 17 and communicating flow path 18). From the above viewpoints, in the present invention, the flow path area of ​​the first throttling section 21 formed in the main passage section 16 is set to be larger than the flow path area of ​​the second throttling section 22 formed in the branch passage section 17, thereby ensuring that a pressure difference is generated between the branch passage sections 17 and 18 while ensuring that pressure fluctuations occur in the branch passage sections 17 and 18 when the patient is exhaling or breathing out.

[0014] According to the cannula of the present invention, by connecting the supply passage 7 to the gas supply source 1 and the connecting passage 8 to the respiration detection unit 2, the gas supply source 1, the nozzle 6, and the respiration detection unit 2 can be arranged in series in the upstream-downstream direction in the order listed. As described above, according to the present invention, in combination with the first throttle portion 21 formed in the main passage portion 16 of the connecting passage 8, the first throttle portion 21 can restrict the smooth inflow of passing gas into the branch passage portions 17 and 18, thereby preventing large fluctuations in pressure within the branch passage portions 17 and 18 due to the inflow of passing gas and minimizing the influence of the respiratory gas (passing gas) on pressure changes in the branch passage portions 17 and 18 caused by the patient's inhalation and exhalation. As described above, according to the present invention, pressure fluctuations due to the patient's inhalation and exhalation can be detected more accurately, and the patient's respiratory condition can be detected more accurately.

[0015] Furthermore, by setting the flow path area of ​​the first throttle section 21 formed in the main passage section 16 larger than the flow path area of ​​the second throttle section 22 formed in the branch passage section (throttled passage) 17, as in the cannula of the present invention, it is possible to ensure that pressure fluctuations occur in the branch passage sections 17 and 18 during the patient's exhalation and inspiration, while also ensuring that a pressure difference is generated between the two branch passage sections 17 and 18. Therefore, by using this cannula, pressure fluctuations due to the patient's exhalation and inhalation can be detected more accurately, and the patient's respiratory condition can be detected more accurately. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a schematic diagram illustrating the configuration of a cannula that constitutes a breathing detection device according to a first embodiment of the present invention. [Figure 2] FIG. 1 is a schematic diagram illustrating the configuration of a breathing detection device. [Figure 3] FIG. 2 is a block diagram of a breathing detection unit. [Figure 4] 10 is a time chart showing an output from a breathing detection unit. [Figure 5] FIG. 10 is a schematic diagram illustrating the configuration of a cannula that constitutes a breathing detection device according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0017] 1 to 4 show a breath detection device and cannula according to a first embodiment of the present invention. As shown in Fig. 2, the breath detection device comprises a gas supply source 1 that generates and supplies oxygen, which is a breathable gas, a breath detection unit 2 that detects pressure changes during exhalation and inhalation, and a cannula 3 arranged between the gas supply source 1 and the breath detection unit 2. The gas supply source 1 of this embodiment is an oxygen concentrator that removes nitrogen from air to produce highly concentrated oxygen, and supplies a maximum of 5 to 10 liters of oxygen per minute.

[0018] The cannula 3 is a flexible tube and includes a nozzle 6 with a pair of left and right nasal tubes 4·4 (see FIG. 1) attached to the nose (face) 5, a supply passage 7 for delivering oxygen supplied from a gas supply source 1 to the nozzle 6, and a connecting passage 8 for connecting the nozzle 6 to the respiration detection unit 2. The nozzle 6 is what is called a "nasal piece" and is composed of a linear nozzle body 9 running in the left-right direction and a pair of left and right nasal tubes 4·4 protruding from the center of the nozzle body 9 in the left-right direction. An opening 10 for supplying gas is formed at the tip of each nasal tube 4, and the nozzle 6 is attached to the nose 5 by inserting the nasal tubes 4·4 into the nasal cavity. In FIG. 2, reference numeral 11 denotes a stopper ring that connects the supply passage 7 and the connecting passage 8.

[0019] In the flow path through cannula 3, where oxygen and the patient's inhaled and exhaled breath flow, the gas supply source 1 side is defined as the upstream side and the breathing detection unit 2 side as the downstream side. In cannula 3, a supply passage 7, a nozzle 6, and a connecting passage 8 are arranged in this order from upstream to downstream. Also, cannula 3 is arranged such that supply passage 7 is arranged upstream of nozzle 6, and connecting passage 8 is arranged downstream of nozzle 6. As shown in FIG. 2, a supply socket 13 is provided at the upstream end of supply passage 7 for connecting supply passage 7 to gas supply source 1. By fitting this socket 13 to an air outlet 14 of gas supply source 1, cannula 3 is connected to gas supply source 1.

[0020] In the breath detection device configured as described above, oxygen supplied from the gas supply source 1 reaches the nozzle unit 6 via the supply passage 7 and is inhaled into the patient's nasal cavity through the opening 10 of the nasal tube 4 for use in breathing. When the patient inhales the oxygen supplied from the supply passage 7, the air and oxygen in the connecting passage 8 are also inhaled into the nasal cavity along with the oxygen, causing a change in the pressure in the connecting passage 8. Furthermore, when the patient exhales through their nose, a portion of the breath (a portion of the exhaled air) flows into the connecting passage 8 through the opening 10 of the nasal tube 4, causing a change in the pressure in the connecting passage 8. As described above, the pressure in the connecting passage 8 changes in accordance with the patient's inhalation and exhalation, and this change is detected by the breath detection unit 2.

[0021] The connecting flow path 8 disposed downstream of the nozzle portion 6 is composed of a main passage portion 16 connected to the downstream end of the nozzle portion main body 9 and two branch passage portions 17 and 18 branched at the downstream end of the main passage portion 16. As shown in FIG. 2, the downstream ends of the branch passage portions 17 and 18 are connected to connectors 19 and 20 of the respiration detection unit 2, thereby connecting the cannula 3 to the respiration detection unit 2. As shown in FIG. 1, a first throttle portion 21 having a smaller flow path area than its upstream and downstream positions is formed in the middle of the main passage portion 16. Furthermore, of the two branch passage portions 17 and 18, one branch passage portion 17 is formed with a second throttle portion 22 having a smaller flow path area than its upstream and downstream positions. As described above, of the two branch passage portions 17 and 18, one branch passage portion 17 is a throttled flow path (hereinafter designated by reference numeral 17) equipped with the second throttle portion 22, and the other branch passage portion 18 is a communicating flow path (hereinafter designated by reference numeral 18) without a throttle portion. As shown in the enlarged view of FIG. 1, the flow path area of ​​the first throttle portion 21 formed in the main passage portion 16 is set to be larger than the flow path area of ​​the second throttle portion 22 formed in the throttle flow path 17.

[0022] The respiration detection unit 2 detects pressure changes during the patient's exhalation and inhalation based on the pressure difference (differential pressure) between the throttle flow path 17 and the communication flow path 18. As shown in FIG. 3, the respiration detection unit 2 includes a differential pressure sensor 25 that detects the differential pressure between the two paths 17 and 18, a respiration curve generation unit 26 that amplifies the output signal of the differential pressure sensor 25 to generate a respiration curve (see FIG. 4), and a pulse signal generation unit 27 that generates a pulse signal (see FIG. 4) indicating the timing of exhalation and inhalation from the output signal of the differential pressure sensor 25. The respiration curve generation unit 26 includes a gain adjustment unit 28 that adjusts and rectifies the output value (gain) from the differential pressure sensor 25 based on the control signal, and an amplifier circuit unit 29 that amplifies the respiration signal obtained by the gain adjustment unit 28. The respiration curve generation unit 26 also includes a center value acquisition unit 30 that acquires a center value from the upper and lower values ​​of the respiration curve. The respiration curve obtained by the respiration curve generation unit 26 is converted into a digital signal, output to a personal computer 31 connected to the respiration detection unit 2, and displayed on its monitor. From the respiration curve obtained in this manner, the patient's respiration state, such as the depth of respiration and the force of respiration, can be detected.

[0023] The pulse signal generating unit 27 is composed of a hysteresis circuit 32 for adjusting a threshold value that determines the timing of pulse output, and a pulse generating circuit 33 for generating a pulse signal from the output signal output from the hysteresis circuit 32. In the example shown in FIG. 4, the threshold value is a center value determined by the positive and negative values ​​of the differential pressure sensor 25. The pulse signal generating unit 27 outputs an expiratory pulse when the value changes from a negative value (a value lower than the threshold value) to a positive value (a value higher than the threshold value) with the threshold value (center value) as the boundary, and an inhalation pulse when the value changes from a positive value to a negative value. The signal output from the pulse signal generating unit 27 in this manner is also output to the personal computer 31 and displayed on its monitor. From the pulse signal obtained in this manner, respiratory conditions such as the length of breathing intervals and irregular breathing can be detected.

[0024] According to the breath detection device of this embodiment configured as described above, the gas supply source 1, nozzle 6, and breath detection unit 2 are arranged in series in the upstream-downstream direction via the supply passage 7 and the connecting passage 8, and the first throttle section 21 is formed in the main passage 16. Therefore, oxygen generated in the gas supply source 1 is sent to the nozzle 6 through the supply passage 7 constituting the cannula, and most of it is sent to the nose 5 through the opening 10 so that it can be inhaled by the patient. Furthermore, some of the oxygen that passes through the nozzle 6 (hereinafter referred to as "passing oxygen") passes through the connecting passage 8 toward the downstream breath detection unit 2, but the first throttle section 21 formed in the main passage 16 can restrict the passing oxygen from smoothly flowing into the branch passages 17 and 18. As described above, according to the breathing detection device of this embodiment, the first restriction portion 21 can restrict the smooth inflow of passing oxygen into the branch passages 17 and 18, thereby preventing large fluctuations in the pressure in the branch passages 17 and 18 due to the inflow of passing oxygen and minimizing the effect of the passing oxygen on pressure changes associated with the patient's inhalation and exhalation in the branch passages 17 and 18. Furthermore, in the breathing detection device of this embodiment, the breathing detection unit 2 is located downstream of the nozzle 6, so that the air flow in the nozzle 6 associated with the patient's inhalation and exhalation is directly transmitted to the branch passages 17 and 18, and the patient's respiratory condition can be detected by detecting the pressure changes in the branch passages 17 and 18. This allows the patient's respiratory condition to be detected more accurately by capturing direct pressure changes caused by the patient's inhalation and exhalation. Furthermore, according to the breathing detection device of this embodiment, when the nozzle portion 6 of the cannula 3 is detached from the nose portion 5, there is almost no change in pressure inside the branch passages 17 and 18, and therefore, by capturing this pressure state (a state in which no pressure change occurs) with the breathing detection unit 2, it is possible to detect that the nozzle portion 6 has been detached from the nose portion 5. As described above, according to this breathing detection device, pressure fluctuations due to the patient's inhalation and exhalation can be detected more accurately, and therefore the patient's respiratory state can be detected more accurately.

[0025] As described above, when the main passage 16 is provided with the first throttle portion 21, it is possible to prevent passing oxygen from flowing into the branch passages 17 and 18. However, if no pressure fluctuation occurs, particularly in the communicating passage 18, when the patient exhales or inhales, it will be impossible to accurately capture the pressure fluctuations caused by the patient's inhalation and exhalation. In other words, if the flow path area of ​​the first throttle portion 21 of the main passage 16 is extremely small, there is a possibility that no pressure fluctuations will occur in the branch passages 17 and 18. On the other hand, the second throttle portion 22 formed in the branch passage (throttled passage) 17 generates a pressure difference with the other branch passage (communicating passage) 18. Therefore, if the flow path cross-sectional area of ​​the second throttle portion 22 is large, no pressure difference will occur between the two branch passages (throttled passage 17 and communicating passage 18). From the above viewpoints, in this embodiment, the flow path area of ​​the first throttle portion 21 formed in the main passage portion 16 is set larger than the flow path area of ​​the second throttle portion 22 formed in the branch passage portion 17, thereby reliably generating pressure fluctuations in the branch passage portions 17 and 18 while reliably generating a pressure difference between the branch passage portions 17 and 18 during the patient's exhalation and inhalation. Therefore, with this breathing detection device, pressure fluctuations due to the patient's exhalation and inhalation can be detected more accurately, and the patient's respiratory condition can be detected more accurately.

[0026] According to the cannula 3 of this embodiment, by connecting the supply passage 7 to the gas supply source 1 and the connecting passage 8 to the respiration detection unit 2, the gas supply source 1, the nozzle 6, and the respiration detection unit 2 can be arranged in series in the upstream-downstream direction in this order. As described above, this cannula 3, in combination with the first throttle portion 21 formed in the main passage portion 16 of the connecting passage 8, can restrict the smooth inflow of passing oxygen into the branch passage portions 17 and 18 by the first throttle portion 21. This prevents large fluctuations in the pressure in the branch passage portions 17 and 18 due to the inflow of passing oxygen, and minimizes the effect of the passing oxygen on pressure changes in the branch passage portions 17 and 18 caused by the patient's inhalation and exhalation. As described above, this cannula 3 can more accurately detect pressure fluctuations due to the patient's inhalation and exhalation, thereby more accurately detecting the patient's respiratory condition.

[0027] In addition, as in the cannula 3 of this embodiment, if the flow path area of ​​the first throttling section 21 formed in the main passage section 16 is set larger than the flow path area of ​​the second throttling section 22 formed in the branch passage section (throttling flow path) 17, it is possible to ensure that a pressure difference is generated between the branch passage sections 17 and 18 while ensuring that pressure fluctuations occur in both branch passage sections 17 and 18 during the patient's exhalation and respiration movements.

[0028] (Second embodiment) Figure 5 shows a breathing detection device and cannula 3 according to a second embodiment of the present invention. This second embodiment differs from the first embodiment in that the nozzle portion 6 is mask-shaped and includes a mask portion main body 37 that covers the nose and mouth of the human face 5, and string-like ear hooks 38 that are hooked onto the human ears to secure the mask portion main body 37. Since other points are the same as those in the first embodiment, the same members are designated by the same reference numerals and their description will be omitted.

[0029] In the above embodiment, the gas supply source 1 is an oxygen concentrator. However, the present invention is not limited to this. It may also be an oxygen cylinder or a centrally piped oxygen nozzle mounted on the wall of a building. The output destination of the respiration detection unit 2 is not limited to a personal computer 31, but may also be a patient monitoring device, such as a central monitor or bedside monitor, that monitors respiratory status. The present invention is not limited to a respiration detection device in an oxygen therapy device that administers oxygen to patients with respiratory diseases. For example, the present invention can also be applied to a respiration detection device in a testing device that tests olfactory sensitivity. That is, a pungent odor component may be mixed into the respiratory gas supplied by the gas supply source, and the subject may smell this mixture while the breathing condition of the subject is detected by the respiration detection device of the present invention. Furthermore, when the present invention is applied to a testing device that tests olfactory sensitivity as described above, the respiratory gas supplied by the gas supply source may be oxygen or air to which a pungent odor component has been added. When testing olfactory sensitivity using the respiration detection device of the present invention, the threshold of the hysteresis circuit unit 32 may be changed up or down to change the timing of generating expiratory and inhalation pulses, thereby enabling more accurate testing of olfactory sensitivity. [Explanation of symbols]

[0030] 1 Gas supply source 2. Respiration detection unit 3 Cannula 5 Human face (human nose) 6 Nozzle section 7 Feeding passage 8 Connecting Passage 10 aperture 16 Main passage section 17 Branch passage section (throttled passage) 18 Branch passage section (communicating flow path) 21 First throttle section 22 Second throttle section 25 Differential pressure sensor

Claims

1. A breath detection device comprising: a gas supply source (1) for supplying a breathable gas; a breath detection unit (2) having a differential pressure sensor (25) for detecting pressure changes during exhalation and inhalation; and a cannula (3) arranged between the gas supply source (1) and the breath detection unit (2), The cannula (3) has an opening (10) for supplying gas, a nozzle portion (6) to be attached to the human face portion (5), a supply passage (7) for supplying breathing gas supplied from the gas supply source (1) toward the nozzle portion (6), and a connecting passage (8) for connecting the nozzle portion (6) to the breathing detection portion (2); The connecting passage (8) has a main passage portion (16) connected to the nozzle portion (6) and two branch passage portions (17, 18) branched from the main passage portion (16) and having downstream ends connected to the breath detection portion (2), A first throttle portion (21) is formed in the main passage portion (16), One of the two branch passage portions (17, 18) is a throttled flow path (17) having a second throttle portion (22), and the other branch passage portion is a communicating flow path (18) having no throttle portion, A breath detection device characterized in that, when the gas supply source (1) is defined as the upstream side and the breath detection unit (2) is defined as the downstream side, the gas supply source (1), the nozzle unit (6), and the breath detection unit (2) are arranged in series in the upstream-downstream direction in the order listed, via a supply passage (7) and a connecting passage (8).

2. 2. The respiration detection device according to claim 1, wherein a flow path area of ​​the first throttle portion (21) formed in the main passage portion (16) is set larger than a flow path area of ​​the second throttle portion (22) formed in the throttle flow path (17).

3. A cannula disposed between a gas supply source (1) that generates a breathing gas and a breath detection unit (2) that includes a differential pressure sensor (25) that detects pressure changes during exhalation and inhalation, The device comprises a nozzle portion (6) having a gas supply opening (10) and attached to a human face portion (5), a supply passage (7) for supplying a breathing gas supplied from a gas supply source (1) toward the nozzle portion (6), and a connecting passage (8) for connecting the nozzle portion (6) and a breathing detection portion (2), The connecting passage (8) has a main passage portion (16) connected to the nozzle portion (6) and two branch passage portions (17, 18) branched from the main passage portion (16) and having downstream ends connected to the breath detection portion (2), A cannula characterized in that a first throttle portion (21) is formed in a main passage portion (16) and a second throttle portion (22) is formed in either one of the branch passage portions (17, 18).

4. 4. A cannula according to claim 3, wherein the flow area of ​​the first throttle portion (21) formed in the main passage portion (16) is set larger than the flow area of ​​the second throttle portion (22) formed in the branch passage portions (17, 18).

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