WO2024221648A1

WO2024221648A1 - Comfortable device capable of accurately controlling concentration of inhaled gas and simultaneously measuring breath flow

Info

Publication number: WO2024221648A1
Application number: PCT/CN2023/112674
Authority: WO
Inventors: 梁珊凤; 罗英辉; 王璐; 罗远明
Original assignee: 罗远明
Priority date: 2023-04-22
Filing date: 2023-08-11
Publication date: 2024-10-31
Also published as: CN116271378A

Abstract

The present invention relates to a comfortable device capable of accurately controlling the concentration of an inhaled gas and simultaneously measuring a breath flow, comprising a flow and concentration controller, a mask, and a flow meter. The flow and concentration controller consists of an airflow generator (such as an air blower), a medical gas source and a gas mixing assembly, and the flow and concentration controller can output a gas having constant flow and concentration; the mask has a capacity of 50-1000 ml, and comprises a mask body and a proximal pad portion, wherein the proximal pad portion is soft and can fit a face, a gas inlet is formed in the proximal end of the mask body, a blocking plate used for eliminating the impact of airflow on the face is provided on one side of the gas inlet, and the flow meter is arranged at the distal end of the mask body. Airflow having constant flow and concentration output by the flow and concentration controller enters from the proximal end of the mask and then flows out of an exhaust port at the distal end of the mask through the flow meter. The device can promote the discharge of an exhaled gas, eliminate the breathing resistance and the retention of the exhaled gas CO2, can provide a gas having constant flow and concentration for a subject, and can accurately measure the breath flow comprising a tidal volume and minute ventilation when various medical gases are inhaled.

Description

A comfortable device capable of accurately controlling the concentration of inhaled gas and simultaneously detecting the respiratory flow

Technical field:

The invention relates to a device for detecting the inhalation and breathing flow of medical gas with a constant concentration.

Background technology:

Quantification of respiratory airflow during sleep is often achieved by wearing a mask connected to a flow sensor. This connection method increases the "dead space capacity" and respiratory resistance due to the lengthened pipe, which can cause the subject to have difficulty breathing and affect sleep. It can also cause an increase in pressure inside the mask, resulting in gas entering and exiting the part of the mask in contact with the face (leakage), thereby affecting the accuracy of gas flow measurement. "Dead space capacity" is a physiological term, which refers to the inability of exhaled air to be discharged into the atmosphere, resulting in part of the gas inhaled in the next respiratory cycle being the exhaled air of the previous cycle. Due to the high _CO2 content and low oxygen concentration in exhaled air, an increase in dead space capacity can increase the _CO2 concentration in the body and aggravate hypoxia, which can further aggravate the condition of patients with respiratory failure. In order to avoid air leakage, the headband is usually tightened, which increases the pressure on the face, causes discomfort, and affects sleep quality. In addition, in air-conditioning or cold indoor environments, due to the high temperature of the exhaled air, water droplets may form in the mask cavity when it encounters cold, which not only affects the measurement of the flow rate, but also may cause excessive accumulation of water droplets in the mask, which may flow back to the face and aggravate the subject's discomfort.

Inhalation of medical gases such as oxygen, carbon dioxide, and hydrogen is an important method for treating respiratory diseases. In order to achieve the therapeutic effect when inhaling medical gases, it is necessary to ensure the concentration of the inhaled gas and detect the respiratory flow under the inhaled gas, including tidal volume and minute ventilation. When oxygen is delivered through a nasal cannula, the nasal cannula affects the fit between the mask and the face, causing air leakage, which affects the accurate measurement of the respiratory airflow. At the same time, when oxygen is delivered through a nasal cannula, the concentration of inhaled respiratory tract oxygen varies with the respiratory rhythm and depth of breathing, making it difficult to accurately control the concentration of the inhaled gas. If additional holes are set on the mask to input medical gases, the concentration of the inhaled gas will still vary with the breathing pattern, and the preset therapeutic effect cannot be achieved. Clinically, The mask used for non-invasive ventilation is often provided with a small through hole for connecting to the central oxygen supply device in the hospital, the oxygen concentrator for home use or the oxygen cylinder to achieve oxygen therapy. _CO2 can also be input through the through hole to supplement the _CO2 of patients with overventilation and increase the blood _CO2 concentration. However, when oxygen therapy or _CO2 gas supplementation is performed through the small through hole, if the respiratory rate increases, the gas concentration in the mask decreases, and the expiratory phase is prolonged, the gas accumulates in the mask, the concentration of the inhaled gas increases, and if the patient stops breathing, the concentration of the inhaled gas may further increase. When _CO2 is input, inhaling too high a concentration of _CO2 may cause awakening and impair sleep quality. In addition, due to the stimulation of airflow, the flow rate when medical gas is directly input from the nasal cavity often does not exceed 5 liters/minute.

If a sufficient flow of evenly mixed gas can be continuously input from the proximal end of the mask and discharged through the distal end of the mask, the concentration of the inhaled gas can be kept constant. If the distal end of the mask is connected to a flowmeter, the inhaled gas flow can be accurately measured under a constant inhaled gas concentration. We invented an oxygen therapy-related device (patent number ZL 2018 1 0388945.3) earlier, which includes a mask with a large hole at the distal end. By inputting evenly mixed high-flow gas from the proximal end of the mask, the patient inhales, and the excess gas is discharged through the distal end of the mask. When exhaling, the high-flow gas input into the mask is discharged from the distal exhaust port and flowmeter together with the exhaled gas. Since there is a large exhaust port at the distal end that is connected to the atmosphere, the internal pressure of the mask is always zero and there is no breathing resistance. However, the evenly mixed high-flow airflow is input from the proximal end of the mask, and the airflow can impact the face and mouth and nose. Especially in a large airflow or cold environment, the subject may feel cold and uncomfortable, or even unbearable.

Summary of the invention

To overcome the above problems, we invented a device that can precisely control the inhaled gas concentration, accurately measure the respiratory airflow, and is comfortable to wear.

To achieve the above object, the present invention is implemented by the following scheme:

The invention discloses a comfortable device which can accurately control the concentration of inhaled gas and detect the breathing flow simultaneously, comprising a flow concentration controller which can be used to accurately control the concentration of inhaled gas, a mask and a flow meter.

The flow concentration controller consists of an air flow generator, a medical gas source (which can be oxygen, CO ₂ or hydrogen, etc.) and a gas mixing component. Its principle is similar to an oxygen therapy-related device invented by us earlier (the patent authorization number is ZL 2018 1 0388945.3). Specifically, a constant airflow is generated by a blower, which is mixed evenly with the gas (oxygen, CO ₂ ) from the medical gas source and then input into the mask. The air supply volume can be monitored by the flow sensor built into the flow concentration controller and adjusted by manual, automatic feedback, or a combination of manual and automatic feedback. The adjustment method can be adjusted by adjusting the speed of the blower or by controlling the size of the pipeline through a valve. The gas concentration can be monitored by the concentration sensor built into the flow concentration controller and the gas volume from the medical gas source can be adjusted by manual, automatic feedback, or a combination of manual and automatic feedback to adjust the air supply concentration.

The mask is a gas container, and its effective gas capacity can be set to any value between 50-1000ml. It can be made of metal, plastic, silicone and other materials that can form a container, and the shape can be cylindrical, rectangular, elliptical or other arbitrary shapes. The face contact end (proximal end) of the mask is the same as that of a conventional mask, and its material can be made of soft and thin materials such as plastic and silicone to ensure that the face and the mask are tightly connected. There are one or more air inlets at the proximal end of the mask, and the outer side of the air inlet is connected to the air supply pipe to receive the air with a constant flow rate generated by the blower or the medical gas with a constant flow rate and concentration after uniform mixing. A baffle is provided on the inner side of the mask at the air inlet to reduce or prevent the impact of the air flow on the mouth, nose and face. The baffle can be vertical or angled, with the inner angle facing the air inlet and the far end of the mask, and the angle range is any value between 30° and 180°. There is one or more large holes at the far end of the mask. The exhaled air of the subject and the gas from the air supply pipe are all discharged from the large holes at the far end of the mask and the flow meter connected to it, so that the pressure inside the mask is always zero.

The flow meter can be a common differential pressure flow meter, an electromagnetic flow meter, an impeller flow meter, an ultrasonic flow meter, a mass flow meter, etc. It can also be a flow meter with an analog-to-digital conversion function or a flow meter with both detection and display functions. The ventilation aperture of the flow meter is large enough, with a diameter of more than 1 ^cm2 , to ensure smooth exhaust and zero pressure inside the mask. For adults, the ideal ventilation aperture is 3 ^cm2 or even larger. There are 2-4 headband interfaces outside the mask for fixing the mask so that the mask can be stably fixed on the face.

The following example illustrates this.

When measuring the respiratory flow of the subject when inhaling a mixed gas with a hydrogen concentration of 2%, let the subject wear a mask connected to a flowmeter. Assume that the gas capacity of the mask is 500ml, the gas flow rate at the mask inlet is 60L/min, and the _H2 concentration is 2%. Open the high-pressure _H2 gas cylinder to allow it to output 100% pure hydrogen gas, adjust the output flow of the blower, when the final output flow of the flow concentration controller is 60L/min, and the _H2 concentration is 2%, then the air flow from the blower is 58.8 liters/min, and the flow from the CO2 _gas cylinder is 1.2 liters/min (the output gas _H2 concentration is 1.2*100%/(1.2+58.8)=2%). When the gas is delivered to the mask, the air flow diffuses around the baffle under the action of the baffle, fills the mask and flows to the far end to be discharged through the flowmeter. Due to the effect of the baffle, the impact of the input air flow on the patient's face and mouth and nose is eliminated, and the patient does not feel uncomfortable. When the subject inhales, he inhales the gas delivered to the mask from the flow concentration controller, which reduces the gas flowing out of the flow meter; when exhaling, the subject's exhaled gas is discharged from the far end of the mask through the flow meter together with the airflow output from the gas flow concentration controller, which increases the gas flowing out of the flow meter. When breathing stops, the airflow discharged through the far end flow meter is equal to the airflow input to the mask, that is, the basic flow of 60L/min. The flow during breathing fluctuates up and down on the basis of 60L/min, so as to measure the inspiratory flow and expiratory flow.

Under certain conditions, such as during exercise or sleep, if you want to measure the respiratory flow including tidal volume and minute ventilation when breathing air, you can fix the mask with a headband, connect the flowmeter with an adapter, and adjust the flow concentration controller to output a predetermined flow of air to the mask. Since the airflow velocity output from the flow concentration controller is large, it can promote the discharge of exhaled air. Moreover, the airflow output from the flow concentration controller continuously flushes and replaces the gas containing exhaled air in the mask, so that the gas near the mask does not contain exhaled air during inhalation, avoiding repeated breathing caused by the dead space of traditional masks. If the subject's inspiratory flow rate is accidentally greater than the gas input to the mask, the subject can inhale the gas from the flow concentration controller left in the exhalation phase, and the inhaled gas also does not contain exhaled air.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

1. The flow meter connected to the exhaust port at the far end of the mask has a large inner diameter, and the pressure inside the mask is almost zero during inhalation and exhalation. At the same time, continuous high-flow airflow is input at the near end of the mask to eliminate additional inhalation resistance; the high-flow airflow then flows out from the flow meter at the far end to promote the discharge of exhaled air.

2. The high-flow airflow continuously input through the proximal end of the mask can flush and replace the exhaled air, eliminating the retention of carbon dioxide in the mask, and eliminating repeated breathing and dead space ventilation.

3. Since the mask has a large exhaust port and its internal pressure is zero, there is no need to over-tighten the headband when wearing the mask. You only need to fit the mask to your face to prevent air leakage, thereby reducing the discomfort of wearing the mask and reducing the impact on sleep.

4. As there is continuous airflow passing through the mask and flow meter channels to flush the exhaled air, it can prevent the exhaled air from turning into condensed water in a cold environment, which not only ensures the accuracy of the measurement, but also eliminates the irritation of condensed water to the face.

5. The air inlet of the mask of this device has a baffle to eliminate the direct impact of high-flow air from the air supply pipe or cold air in a cold environment on the face, mouth and nose, thereby increasing the comfort of the subject.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be further described below in conjunction with the implementation diagram.

FIG. 1 is a schematic diagram of a device that can accurately control the concentration of inhaled gas and detect the respiratory flow rate at the same time. It is composed of a flow concentration controller 1, a mask 2 for detecting tidal volume, and a flow meter 3. The mask 2 is composed of a mask body 4, a cushion 5 that fits the face, and a baffle 6. The capacity of the mask body 4 is 50-1000 ml. The mask body 4 and the baffle 6 are mainly made of lightweight materials such as plastic, silicone, metal, etc. The material of the cushion 5 can be soft silicone, gel or foam plastic, etc. The baffle 6 can be vertical or angled, with the inner angle facing the air inlet and the far end of the mask, and the angle range can be adjusted to any value in the range of 30-180°. The air inlet pipe joint 7 is used to connect the mask air inlet and the gas output pipe 8. The air inlet pipe joint 7 can be a straight-through, angled, or 360-degree rotatable joint made by overlapping the pipes, so that the subject can turn his head at will after wearing the mask, and keep the mask in close contact with the face to avoid air leakage. There are 1-2 headband fixing clips 9 on both sides of the mask 2. A flow meter 3 is provided at the far end 10 of the mask body 4. The flow meter 3 can be a common differential pressure flow meter, a flow meter with analog-to-digital conversion function, or a flow meter with both detection and display functions. It can be connected to the biological signal processor through a connecting line 11 to monitor, store and analyze data in real time. The medical gas source (oxygen, _CO2 , hydrogen or nitrogen, etc.) is mixed evenly in the flow concentration controller with the air entering from the air inlet 13 through the air inlet 12. When the subject When it is necessary to detect the respiratory airflow and tidal volume, after the subject wears the mask, the airflow with a constant flow rate and concentration output by the flow concentration controller enters the mask cavity through the gas output pipe 8 and the air inlet pipe joint 7. When the patient inhales, the gas delivered to the mask 2 by the flow concentration controller 1 is inhaled, which reduces the gas flowing out through the flow meter 3; when the patient exhales, the exhaled gas is discharged from the far end 10 of the mask through the flow meter 3 together with the airflow output by the flow concentration controller 1, which increases the gas flowing out through the flow meter, thereby measuring the inspiratory flow and expiratory flow.

Fig. 2 is a schematic diagram of the first embodiment of the flow concentration controller of the present invention. An air flow generator 14 (such as a blower) is connected to the air inlet 13 to generate an air flow with a sufficient flow rate. The medical gas source passes through the flow control valve 15 from the air inlet 12 and enters the gas mixing area 16 to be evenly mixed with the air flow generated by the blower 14. The gas mixing area 16 can be a straight pipe, a curved pipe or a chamber of any other shape. The evenly mixed airflow flows through the gas flow concentration sensor 17 and flows out from the air flow output port 18. The display 19 can display the gas flow and concentration of the output airflow in real time. The signal detected by the gas flow concentration sensor 17 can be automatically transmitted to the controller 20, and the controller 20 controls the blower control component 21 and the flow control valve 15 so that the output airflow velocity and concentration are automatically adjusted to the set value, that is, the flow concentration controller 1 can continuously output a mixed airflow with a constant flow rate concentration. The operator can also manually adjust the flow and concentration through the knob or touch panel set by the flow concentration controller 1.

Fig. 3 is a schematic diagram of the second embodiment of the flow concentration controller of the present invention. The medical gas passes through the flow control valve 15 from the air inlet 12, mixes with the air entering from the air inlet 13, and is further evenly mixed by the blower.

Fig. 4 is a schematic diagram of the third embodiment of the flow concentration controller of the present invention. The high-pressure air flows from the air inlet 13 through the flow control valve 22, mixes with the medical gas from the air inlet 12 through the flow control valve 15, and then enters the gas mixing area 16 to achieve uniform mixing of the gas. The uniformly mixed airflow flows through the gas flow concentration sensor 17, flows out from the airflow output port 18, and is connected to the mask and the flow meter through the pipeline. The display 19 can display the gas flow and concentration of the output airflow in real time. The signal detected by the gas flow concentration sensor 17 can be transmitted to the controller 20, and the controller 20 controls the valves 15 and 22 to automatically adjust the output airflow velocity and concentration to the set values.

FIG5 is a partial front view of the first embodiment of the face mask of the present invention. It includes a face mask cushion inner surface 5, a face mask body 4, Angle baffle 6, air inlet duct 7 and mask distal end 10 connected to flow meter.

Fig. 6 is a structural diagram of a fixed or detachable angled baffle assembly in a mask. The angled baffle 6 is composed of an air intake duct connection portion 23, an angled edge 24 connected to the connection portion 23, and a suspended angled edge 25, with the inner angle facing the air intake port and the far end of the mask, and the angle range of the angled baffle is any value between 30 and 180 degrees.

FIG7 is a schematic diagram of detecting the tidal volume of the patient's or subject's breathing. The patient wears the mask 2 through the headband fixing bayonet 9 and the connected headband 26, so that the mask cushion 5 fits the face. The flow concentration controller delivers gas to the mask through the mask air inlet 7 connected to the air supply pipeline. The airflow direction through the air inlet pipeline is shown by arrow 27. After the airflow enters the mask, under the action of the angle baffle 6, the direction is changed as shown by arrow 28 and flows to both sides of the mask to fill the mask, and is discharged through the flow meter 3 in the direction shown by arrow 29. When the subject holds his breath or stops breathing, the gas flow through the flow meter 3 will be consistent with the flow of gas 27 output by the flow concentration controller; when the subject exhales, the exhaled gas flow 30 and the gas 28 output by the flow concentration controller together form the gas flow 29 through the flow meter 3. At this time, the gas flow through the flow meter 3 is equal to the sum of the flow of the subject's exhaled gas 30 and the flow of gas 27 of the gas output device.

Fig. 8 is a schematic diagram of detecting the inspiratory tidal volume of a patient or a subject. The patient wears the mask 2 through the headband fixing bayonet 9 and the connected headband 26, so that the mask cushion 5 fits the face. The flow concentration controller delivers gas to the mask through the mask air inlet 7 connected to the air supply pipeline. The air flow direction in the air inlet pipeline is shown by arrow 27. When the air flow enters the mask, the direction is changed as shown by arrow 28 under the action of the angle baffle 6, and flows to both sides of the mask to fill the mask. When the subject inhales, the air flow 28 or the air flow flowing to both sides of the mask will enter the respiratory tract as shown by arrow 31. When the subject's inspiratory flow is less than the air flow output by the flow concentration controller, the excess gas is discharged through the far end of the flow meter 3 as shown by arrow 29. At this time, the gas flow measured by the flow meter 3 is the difference between the air flow 27 and the patient's inspiratory flow 31.

The following is an example of flow simulation detection. As shown in FIG9 , a calibration cylinder 32 with a scale of 0.5 L, 1 L, and 2 L is used to simulate the breathing pattern of the subject, that is, the tidal volume is 0.5 L, 1 L, 1.5 L, and 2 L. The calibration cylinder 32 is rotated The connector 33 is closely connected to the mask 2, and the flow concentration controller 1 is connected to the air inlet 7 of the mask 2 through the pipe 8. The flow concentration controller 1 outputs an air flow at a constant flow rate (40L/min). When the simulated subject inhales, the pull rod 34 of the calibration cylinder is pulled to the 0.5L, 1L, 1.5L, and 2L capacity positions of the cylinder respectively, and the gas flow rate curve is below the baseline flow rate, that is, the flow rate detected by the flowmeter is less than the baseline flow rate; when the simulated subject exhales, the piston of the calibration cylinder is pushed to discharge all the gas in the cylinder, and the gas flow rate curve is above the baseline flow rate, that is, the flow rate detected by the flowmeter 3 is greater than the baseline flow rate, as shown in the curves of Figures 11, 12, 13, and 14.

FIG10 is a schematic diagram of simulating breathing by pulling the pull rod 34 of the calibration cylinder 32 to the 0.5L capacity position of the gas cylinder. FIGA shows that a 0.5L capacity calibration cylinder is used to simulate breathing when the flow concentration controller outputs an air flow of 40L/min, and the gas flow rate fluctuates around the base flow rate (40L/min) to form a breathing flow rate curve. FIGB shows that the base flow rate of 40L/min is set as the baseline flow rate (0L/min), and the software is used to calculate the inspiratory capacity, i.e., the curve area under the baseline flow rate, which are 0.4981L, 0.4869L, 0.4916L, 0.4920L, and 0.5069L, respectively, which is less than 3% of the standard capacity error of 0.5L, which is basically consistent.

Fig. 11 is a schematic diagram of simulating breathing by pulling the pull rod 34 of the calibration cylinder 32 to the 1L capacity position of the gas cylinder. Fig. A shows that a 1L capacity calibration cylinder is used to simulate breathing when the flow concentration controller outputs 40L/min of air flow, and the gas flow rate fluctuates around the base flow rate (40L/min) to form a breathing flow rate curve. Fig. B shows that the base flow rate of 40L/min is set as the baseline flow rate (0L/min), and the software is used to calculate the inspiratory capacity, i.e., the curve area under the baseline flow rate, which are 0.9903L, 0.9977L, 0.9773L, 0.9851L, and 0.9759L, respectively, which is less than 3% of the standard capacity error of 1L, which is basically consistent.

Fig. 12 is a schematic diagram of simulating breathing by pulling the pull rod 34 of the calibration cylinder 32 to the 1.5L capacity position of the gas cylinder. Fig. A shows that a 1.5L capacity calibration cylinder is used to simulate breathing when the flow concentration controller outputs 40L/min air flow, and the gas flow rate fluctuates around the base flow rate (40L/min) to form a breathing flow rate curve. Fig. B shows that the base flow rate of 40L/min is set as the baseline flow rate (0L/min), and the software is used to calculate the inspiratory capacity, i.e., the curve area under the baseline flow rate, which are 1.4805L, 1.4717L, 1.4841L, and 1.4755L, respectively, which is less than 2% of the standard capacity error of 1.5L, which is basically consistent.

Figure 13 is a schematic diagram of pulling the rod 34 of the calibration cylinder 32 to the 2L capacity position of the cylinder to simulate breathing. Figure A shows that when the flow concentration controller outputs 40L/min air flow, a 2L capacity calibration cylinder is used to simulate breathing, and the gas flow rate is The basic flow rate (40L/min) fluctuates up and down to form a respiratory flow rate curve. Figure B sets the basic flow rate of 40L/min as the baseline flow rate (0L/min), and uses software to calculate the inspiratory capacity, that is, the curve area under the baseline flow rate, which are 1.9927L, 1.9627L, 1.9769L, and 1.9915L, respectively, with an error of less than 2% with the standard capacity of 2L, which is basically consistent.

The above specific implementation is a preferred embodiment of the present invention. Any method of accurately detecting respiratory flow by inputting a constant gas concentration and flow from the proximal end of the mask through an inlet with a baffle into an open mask is within the protection scope of this patent.

Claims

A comfortable device that can accurately control the concentration of inhaled gas and simultaneously detect the respiratory flow, characterized in that it includes a flow concentration controller, a mask and a flow meter, the flow concentration controller is composed of a constant flow generator (such as a blower), a medical gas source and a gas mixing component, and this flow concentration controller can output an airflow with a constant flow rate and concentration; an air inlet is provided at the proximal end of the mask, an air flow baffle is provided on the inner side of the mask at the air inlet, and a large-caliber flow meter is provided at the distal end of the mask body.
According to claim 1, a comfortable device that can accurately control the concentration of inhaled gas and simultaneously detect the respiratory flow rate is characterized in that the medical gas can be oxygen, carbon dioxide, nitrogen, helium, hydrogen, or a mixed gas.
According to claim 1, a comfort device that can accurately control the concentration of inhaled gas and simultaneously detect the respiratory flow rate is characterized in that the gas mixing method can be a curved pipe area, an enlarged and reduced pipe area, or an air intake pipe for the medical gas to be connected to the blower after the gas is mixed.
According to claim 1, a comfort device that can accurately control the concentration of inhaled gas and simultaneously detect the respiratory flow rate is characterized in that the proximal end of the mask body has an air inlet, and the air inlet can be one or more airflows received from the flow concentration controller.
According to claim 1, a comfort device that can accurately control the concentration of inhaled gas and simultaneously detect the respiratory flow rate is characterized in that the mask capacity is an arbitrary value of 50-1000ml.
According to claim 1, a method for accurately controlling the concentration of inhaled gas and simultaneously A comfortable device for detecting respiratory flow, characterized in that the flow meter aperture at the far end of the mask body is larger than 1 cm 2 , and the pressure inside the mask is kept almost zero.
According to claim 1, a comfortable device that can accurately control the concentration of inhaled gas and simultaneously detect the respiratory flow rate is characterized in that the proximal cushion of the mask fits lightly against the face, and air leakage can be avoided without tightening the headband or applying excessive pressure.
According to claim 1, a comfort device that can accurately control the concentration of inhaled gas and simultaneously detect the respiratory flow rate is characterized in that the baffle can be vertical or can form an angle, the inner angle is toward the air inlet and the far end of the mask, and the angle range is any value between 30-180°.
According to claim 1, a comfort device that can accurately control the inhaled gas concentration and simultaneously detect the respiratory flow rate is characterized in that: the flow meter can be a common differential pressure flow meter, or other types of flow meters such as electromagnetic flow meters, impeller flow meters, ultrasonic flow meters, mass flow meters, etc., or a flow meter with analog-to-digital conversion function or with both detection and display functions.
According to claim 1, a comfort device that can accurately control the concentration of inhaled gas and simultaneously detect the respiratory flow rate is characterized in that the gas flow rate input into the mask is any value between 10-300 liters/minute.