Co2 collection high flow nasal oxygen cannula

Abstract

The application provides a CO2 collection high-flow nasal oxygen tube, which comprises a nasal oxygen cavity, a fixing belt and a breathing connection tube, the nasal oxygen cavity is provided with an intranasal tube and a CO2 collection tube cavity in communication, a CO2 collection tube is embedded in the CO2 collection tube cavity, and a water-blocking and air-permeating section is arranged at the head end of the CO2 collection tube; during high-flow oxygen inhalation treatment, the CO2 collection tube is placed into the patient's nasal cavity through the CO2 collection tube cavity, and the end-tidal CO2 of the patient is continuously monitored synchronously, so that the nasal cavity mucus is prevented from blocking the cavity, and the structure is simple, the cost is low, and the safety is reliable.

Description

Technical Field

[0001] This invention relates to the field of medical devices, and more particularly to a high-flow nasal oxygen cannula for CO2 collection. Background Technology

[0002] High-flow oxygen therapy uses a high-flow humidification therapy device and a dedicated high-flow nasal cannula to provide patients with constant temperature and humidity high-flow oxygen therapy. It is commonly used for moderate hypoxemia and can also be used for non-intubated intravenous anesthesia.

[0003] High-flow oxygen therapy can slightly obstruct a patient's exhalation, easily leading to CO2 accumulation, which can even be life-threatening in severe cases. Therefore, it is crucial to monitor the patient's blood CO2 levels closely during high-flow oxygen therapy to promptly assess their condition. If the patient's condition improves, switch to regular oxygen therapy; if the condition worsens, switch to non-invasive or invasive mechanical ventilation.

[0004] Existing high-flow nasal oxygen tubes cannot use CO2 monitors to non-invasively collect and monitor patients' end-tidal CO2 in real time. Instead, they can only collect arterial blood and send it for blood gas analysis to assess the condition, which increases patient suffering and medical costs. Furthermore, continuous monitoring is not possible, which delays the assessment of the condition.

[0005] There is an urgent clinical need for a high-flow nasal oxygen tube that can continuously collect patients' exhaled gas samples and monitor patients' end-tidal CO2 in real time. Summary of the Invention

[0006] To address the aforementioned deficiencies in existing technologies, this invention provides a high-flow CO2 collection nasal oxygen cannula, comprising a nasal oxygen chamber for oxygen supply in the nasal cavity, a fixing strap for securing the nasal oxygen chamber at the anterior position of the upper lip and nose, and a breathing connector tube for connecting the nasal oxygen chamber to the oxygen supply port of a high-flow humidified oxygen therapy device. An intranasal tube for supplying oxygen to the nasal cavity is connected to the nasal oxygen chamber. A CO2 collection lumen is positioned corresponding to the nostril in the nasal oxygen chamber. A CO2 collection tube is fitted within the CO2 collection lumen, with a CO2 collection interface extending from the tail end of the CO2 collection tube outside the CO2 collection lumen. The head end of the CO2 collection tube extends through the CO2 collection lumen and enters the patient's nasal cavity.

[0007] The CO2 collection tube is positioned to correspond to the nasal tube. The tip of the CO2 collection tube is partially contained within the CO2 collection tube and the nasal tube. The CO2 collection tube exits the CO2 collection tube and extends into the patient's nasal cavity through the nasal tube.

[0008] The head end of the CO2 collection tube is designed as a hollow tube;

[0009] Alternatively, the head end of the CO2 collection tube may be made of a water-resistant and breathable material;

[0010] Alternatively, the head end of the CO2 collection tube can be made into a perforated tube and covered with a water-resistant and breathable layer.

[0011] The outer wall of the CO2 collection tube is provided with a super-slippery coating; or, the CO2 collection tube is made of a super-slippery material.

[0012] The CO2 collection tube has a limiting block located 50-10 mm from the tip, and the limiting block is located outside the CO2 collection tube lumen on the side away from the nasal oxygen chamber.

[0013] A dryer is connected to the CO2 collection tube, and water-absorbing particles are placed in the dryer.

[0014] The CO2 collection tube is fitted with a perforated cap at the tail end, and the perforated cap has a through hole in the middle that fits the CO2 collection tube. The CO2 collection tube is rotated to cover the tail end of the CO2 collection tube, and a flexible gasket that fits the CO2 collection tube is placed at the bottom of the perforated cap. The CO2 collection tube passes through the through hole in the perforated cap and the flexible gasket and enters the CO2 collection tube.

[0015] Tighten the perforated cap to the tail end of the CO2 collection tube, and the flexible washer will be compressed and deformed to lock the CO2 collection tube; loosen the perforated cap to the tail end of the CO2 collection tube, and the flexible washer will return to its original position, releasing the CO2 collection tube.

[0016] The beneficial effects of this invention are:

[0017] 1. To achieve continuous dynamic monitoring of end-tidal CO2 during high-flow oxygen therapy and to promptly assess the patient's condition;

[0018] 2. Reduce the need for regular invasive blood gas analysis when using high-flow oxygen therapy to lower costs and reduce discomfort;

[0019] 3. The anti-clogging design at the tip prevents mucus from entering the CO2 collection tube and causing monitoring interruption, resulting in good performance.

[0020] 4. Simple structure, low cost, and easy to promote. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of the present invention before use;

[0022] Figure 2 This is a schematic diagram of the structure of the present invention in use;

[0023] Figure 3 This is a partial cross-sectional view during the implementation of the present invention;

[0024] Figure 4 This is a schematic diagram of the CO2 collection tube after it has been removed according to the present invention.

[0025] In the picture,

[0026] 1. Nasal oxygen chamber; 11. Nasal tube; 12. CO2 collection lumen; 13. CO2 collection tube; 14. CO2 collection interface; 15. Limiting block; 16. Dryer; 2. Fixing strap; 3. Breathing connection tube. Detailed Implementation

[0027] To enable those skilled in the art to better understand the technical solutions of the present invention and to make the above-mentioned features, objectives, and advantages of the present invention clearer and easier to understand, the present invention will be further described below with reference to embodiments. These embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention.

[0028] The CO2 collection high-flow nasal oxygen cannula of this invention includes a nasal oxygen chamber 1 for supplying oxygen to the nasal cavity, a fixing strap 2 for fixing the nasal oxygen chamber 1 at the anterior position of the upper lip and nose, and a breathing connector 3 for connecting the nasal oxygen chamber 1 to the oxygen supply port of a high-flow humidified oxygen therapy device. The nasal oxygen chamber 1 is connected to an intranasal tube 11 for supplying oxygen to the nasal cavity. This is the basic structure of existing high-flow nasal oxygen cannulas. In actual use, the breathing connector 3 is connected to the high-flow humidified oxygen therapy device through the breathing tubing, the fixing strap 2 fixes the nasal oxygen chamber 1 at the anterior position of the patient's upper lip and nose, and the free end of the intranasal tube 11 is inserted into the patient's nasal cavity. High-flow-rate humidified oxygen therapy devices deliver a high-flow-rate, heated, and humidified oxygen-enriched stream of 20-100 L / min through the free end of the nasal cannula 11 into the patient's nasal cavity at high speed. Due to the confined space of the nasal cavity, a positive pressure of 2-7 cmH2O is created locally, similar to the PEEP breathing mode of a ventilator. With even a slight inhalation, a large amount of gas rushes into the patient's lungs, promoting alveolar expansion and oxygenation. However, this is slightly detrimental to exhalation, easily leading to insufficient CO2 expulsion and CO2 accumulation in the blood, posing a risk. Therefore, monitoring the CO2 in the patient's exhaled breath is crucial during high-flow-rate oxygen therapy. This allows for timely detection of changes in the patient's respiratory condition, enabling the discontinuation of high-flow-rate oxygen therapy and transition to regular oxygen therapy or mechanical ventilation.

[0029] To enable end-tidal CO2 monitoring during high-flow oxygen therapy, a CO2 collection lumen 12 is provided at the position of the nostril in the nasal oxygen cavity 1; a CO2 collection tube 13 is adapted to be installed inside the CO2 collection lumen 12; a CO2 collection interface 14 is provided at the tail end of the CO2 collection tube 13 extending out of the CO2 collection lumen 12; and the head end of the CO2 collection tube 13 extends through the CO2 collection lumen 12 and enters the patient's nasal cavity.

[0030] The CO2 collection lumen 12 can be arranged adjacent to and parallel to the nasal tube 11, with the CO2 collection lumen 12 located outside the nasal tube 11. In use, the CO2 collection tube 13 runs parallel to the nasal tube 11 within the CO2 collection lumen 12, with part of the CO2 collection tube 13 and the nasal tube 11 simultaneously encased in the shallow part of the nasal cavity. After exiting the CO2 collection lumen 12, the CO2 collection tube 13 extends beyond the length of the nasal tube 11, penetrating 30-70 mm into the nasal cavity.

[0031] Of course, such as Figure 1 , Figure 2 and Figure 3 As shown, a better solution is that the CO2 collection lumen 12 is connected to the nasal tube 11, with the CO2 collection lumen 12 corresponding to the nasal tube 11. In use, the CO2 collection tube 13 enters the nasal tube 11 through the CO2 collection lumen 12, with part of the CO2 collection tube 13 enclosed within the nasal tube 11, which is located in the superficial part of the nasal cavity; after exiting the nasal tube 11, the CO2 collection tube 13 extends 30-70mm into the nasal cavity.

[0032] The primary function of the CO2 collection lumen 12 is to house the CO2 collection tube 13, guiding it into the deep nasal cavity, and even into the nasopharynx, during insertion. The CO2 collection lumen 12 can be positioned to correspond to either the left or right nasal tube 11, with the CO2 collection tube 13 entering the corresponding nasal cavity. Alternatively, the CO2 collection lumen 12 can be positioned to correspond to both nasal tubes 11; in use, one side of the CO2 collection lumen 12 is selected to insert the CO2 collection tube 13 into the corresponding nasal cavity. Specifically, a diameter of 1.5-3 mm for the CO2 collection tube 13 is optimal to ensure its proper functioning. When the CO2 collection tube 13 is inside the nasal tube 11, it does not obstruct the nasal tube 11, ensuring high-flow oxygen supply; when the CO2 collection tube 13 is outside the nasal tube 11, it does not obstruct the nasal cavity, ensuring nasal patency.

[0033] The principle behind this sampling method is as follows: Patients using high-flow nasal cannulas retain spontaneous breathing. During exhalation, the patient overcomes the slight gas pressure from the high-flow oxygen supply and exhales through the nostrils. In the shallow nasal cavity, the airflow is inevitably interfered with by the airflow released from the high-flow nasal cannula 11. Sampling in the shallow nasal cavity will inevitably be inaccurate. When using this product, the end of the CO2 collection tube 13 extends through the CO2 collection lumen 12 into a deeper part of the patient's nasal cavity, with a depth of 50-70 mm being optimal. This avoids interference from the high-flow oxygen supply to the exhaled sample, allowing for accurate collection of the patient's exhaled gas sample, and also reduces the risk of unnecessary discomfort and damage caused by excessive insertion depth.

[0034] Further reference Figure 1 , Figure 2 and Figure 3As shown, the CO2 collection lumen 12 is positioned corresponding to the nasal tube 11. The tip of the CO2 collection tube 13 is movably contained within the CO2 collection lumen 12 and the nasal tube 11. The CO2 collection tube 13 extends from the CO2 collection lumen 12 into the patient's nasal cavity via the nasal tube 11. At the beginning of high-flow oxygen therapy, the tip of the CO2 collection tube 13 is contained within the collection lumen 12 and the nasal tube 11, and does not penetrate deep into the nasal cavity, reducing patient discomfort. When real-time monitoring of the patient's exhaled CO2 is required, the CO2 collection tube 13 is inserted through the CO2 collection lumen 12, and the tip extends beyond the nasal tube 11 to an appropriate depth into the nasal cavity, allowing for real-time monitoring of the patient's exhaled CO2 partial pressure.

[0035] This design is most practical for patients under intravenous anesthesia. Patients do not need to monitor end-tidal CO2 before anesthesia, and the tip of the CO2 collection tube 13 does not need to be inserted into the nasal cavity. When high-flow oxygen is started and anesthesia begins, varying degrees of respiratory depression can easily occur during anesthesia. In this case, inserting the tip of the CO2 collection tube 13 deep into the nasal cavity and connecting it to a monitor allows for simultaneous monitoring of the patient's respiratory status while receiving high-flow oxygen. When respiratory depression is severe (no CO2 waveform, apnea), or when there is a significant accumulation of CO2 in the patient's body (end-tidal CO2 partial pressure greater than 60 mmHg), timely intervention can be taken to avoid serious consequences. Patients experience no discomfort after the CO2 collection tube 13 is inserted deep into the nasal cavity following anesthesia, and it is removed after the patient regains consciousness without any adverse effects. In normally conscious patients, while there may be slight discomfort with the CO2 collection tube 13 inserted deep into the nasal cavity, it is generally tolerable.

[0036] During end-tidal CO2 partial pressure monitoring, the patient's exhaled air is drawn into the CO2 monitoring analysis module through the CO2 collection tube 13 by the CO2 monitor's weak negative pressure pump. Nasal mucus can easily enter and clog the inner lumen of the CO2 collection tube 13. To reduce or avoid clogging, the tip of the CO2 collection tube 13 is further designed as a perforated tube; the perforated tip of the CO2 collection tube 13 increases the passageway for the sampling gas to enter the CO2 collection tube 13, further reducing the negative pressure at the tip of the CO2 collection tube 13, and reducing the probability of nasal mucus entering and clogging the inner lumen of the CO2 collection tube 13.

[0037] Alternatively, the tip of the CO2 collection tube 13 may be made of a water-resistant and breathable material. This material allows gas to pass freely but prevents liquids from passing through, thus avoiding the entry of mucus and its interference with the entry of sampling gas into the CO2 collection tube 13, thereby completely preventing blockage of the inner cavity of the CO2 collection tube 13. Unless all tips of the water-resistant and breathable CO2 collection tubes 13 are covered with mucus, a new tip of the CO2 collection tube 13 must be replaced.

[0038] Alternatively, the tip of the CO2 collection tube 13 can be designed as a perforated tube and covered with a water-resistant and breathable layer. The tip of the CO2 collection tube 13, made of a different material from the rear part of the tube, has a smaller contact area, posing a potential risk of it falling into the deep nasal cavity during use. Replacing it with a perforated tube covered with a water-resistant and breathable layer significantly increases the bonding contact area between the water-resistant and breathable layer and the tip of the CO2 collection tube 13, thus avoiding this risk.

[0039] Furthermore, the outer wall of the CO2 collection tube 13 is provided with a super-slippery coating; or, the CO2 collection tube 13 is made of a super-slippery material. This structure can reduce the friction force on the nasal mucosa when the CO2 collection tube 13 is inserted into the nasal cavity, reducing discomfort and damage during insertion.

[0040] Furthermore, a limiting block 15 is provided at a distance of 50-10mm from the tip of the CO2 collection tube 13. The limiting block 15 is located outside the CO2 collection tube lumen 12 on the side away from the nasal oxygen cavity 1. The limiting block 15 can be set as an adapter in the middle of the CO2 collection tube 13, after which a longer section of the CO2 collection tube 13 is connected, and finally connected to the monitor; or it can be set separately on the outer wall 50-10mm from the tip of the CO2 collection tube 13. Its function is to prevent the CO2 collection tube 13 from being inserted too deeply into the nasal cavity, causing unnecessary discomfort and increasing the risk of damage to the patient's nasal mucosa. At the same time, if the CO2 collection tube 13 inserted into the nasal cavity is too long, it will inevitably bend, making it easier for the CO2 collection tube 13 to become blocked.

[0041] Furthermore, a dryer 16 is connected to the CO2 collection tube 13, and the dryer contains water-absorbing particles. During high-flow oxygen therapy, the gas is a heated and humidified gas, rich in water vapor. This water vapor condenses inside the CO2 collection tube 13, forming water droplets that can easily clog it. The water-absorbing particles in the dryer 16 can remove water vapor from the sampled gas, extending the service life of the CO2 collection tube 13. The dryer 16 is temporarily fixed in the CO2 collection tube 13. When the dryer 16 fails due to absorbing sufficient water vapor, it can be replaced with a new one for continued use.

[0042] When the patient's breathing is stable, their condition improves, and end-tidal CO2 monitoring is no longer necessary, refer to... Figure 4 The CO2 collection tube 13 can then be removed, and the CO2 collection lumen 12 can be sealed, resulting in a product with the same function as an existing high-flow nasal oxygen cannula. Alternatively, the CO2 collection tube 13 can be retracted, allowing the nasal tube 11 to enter and remain within the CO2 collection lumen 12, resulting in... Figure 1 For products in this condition, the CO2 collection tube 13 is kept in the CO2 collection lumen 12 for future use. When needed, it can be reconnected to the monitor to monitor end-tidal CO2 when the patient is receiving high-flow oxygen.

[0043] It should be noted that, in practical use, to prevent interference from the high-flow oxygen flow when collecting the patient's exhaled air sample using the CO2 collection tube 13, the depth of the CO2 collection tube 13 inserted into the nasal cavity is closely related to the flow rate of the high-flow oxygen. Specifically, the depth to which the high-flow gas overcomes the patient's expiratory pressure and enters the nasal cavity during exhalation is positively correlated with the high-flow gas flow rate. The higher the high-flow gas flow rate, the greater the pressure generated when released within the nasal cavity, and the deeper the high-flow airflow enters the nasal cavity during exhalation. Only when the tip of the CO2 collection tube 13 collects the gas sample beyond the area of ​​the nasal cavity affected by the high-flow gas can the purity of the gas sample collected by the CO2 collection tube 13 be ensured—that it represents the patient's exhaled air, rather than a mixture of the patient's exhaled air and the high-flow gas.

[0044] To ensure the purity of the exhaled gas sample collected by the CO2 collection tube 13, the correct usage method is as follows: First, correctly wear the high-flow nasal cannula and start high-flow oxygen administration. Then, slowly insert the CO2 collection tube 13 into the nasal cavity through the CO2 collection lumen 12. Initially, the tip of the CO2 collection tube 13 enters the nasal cavity only superficially, and the collected gas sample is either pure high-flow gas or a mixture of the patient's exhaled gas and high-flow gas. At this time, the CO2 value displayed on the monitor will be significantly low, with abnormal waveforms or even no waveform. Continue inserting the CO2 collection tube 13 into the nasal cavity. At this point, the interference of the high-flow gas with the patient's exhaled gas decreases, and the content of exhaled gas in the gas sample collected by the CO2 collection tube 13 begins to increase, and the CO2 value on the monitor begins to rise. As the CO2 level rises and the waveform begins to normalize, continue inserting the tip of the CO2 collection tube 13 into the nasal cavity. When all the collection holes at the tip of the CO2 collection tube 13 extend beyond the areas of the nasal cavity affected by the high-flow-rate gas, the gas sample collected by the CO2 collection tube 13 will be pure exhaled air from the lungs. At this point, the CO2 value on the monitor will be the correct exhaled CO2 value for the patient, and its CO2 waveform will accurately reflect the patient's respiratory status. At this point, stop inserting the CO2 collection tube 13 into the nasal cavity and begin high-flow-rate oxygen therapy under continuous end-tidal CO2 monitoring. When the oxygen flow rate for high-flow-rate oxygen therapy is increased, the tip of the CO2 collection tube 13 needs to be inserted deeper into the nasal cavity using the above method.

[0045] The usage of a high-flow CO2 nasal cannula is summarized as follows:

[0046] S1; Correctly wear the high-flow nasal oxygen cannula and start high-flow oxygen inhalation; Correctly connect the end of CO2 collection tube 13 to the monitor;

[0047] S2; Slowly insert the tip of the CO2 collection tube 13 into the nasal cavity through the CO2 collection tube lumen 12;

[0048] Meanwhile, observe the CO2 value and waveform displayed on the monitor; until the CO2 value displayed on the monitor is stable and the waveform is normal, fix the CO2 acquisition tube 13.

[0049] S3; When the oxygen flow rate for high-flow therapy is increased, release the CO2 collection tube 13 and repeat the S2 operation.

[0050] Furthermore, to facilitate adjustment of the insertion depth of the CO2 collection tube 13 into the nasal cavity and to temporarily fix the CO2 collection tube 13, a fitting perforated cap is provided at the tail end of the CO2 collection tube lumen 12, with a perforation in the middle of the perforated cap that fits the CO2 collection tube 13. The tail end of the CO2 collection tube lumen 12 is rotated to seal the cap, and a flexible gasket fitted to the CO2 collection tube 13 is provided at the bottom of the perforated cap. The CO2 collection tube 13 passes through the perforation of the perforated cap and the flexible gasket into the CO2 collection tube lumen 12.

[0051] Tighten the perforated cap to the tail end of the CO2 collection tube 12, and the flexible washer will be compressed and deformed to lock the CO2 collection tube 13 in place; loosen the perforated cap to the tail end of the CO2 collection tube 12, the flexible washer will return to its original position, and the CO2 collection tube 13 will be released. This is a temporary fixation structure between the epidural catheter and the syringe, which has been used clinically for a long time and will not be elaborated on further here.

[0052] In summary, this invention connects to the nasal tube 12 to form a CO2 collection lumen 12, and encloses a CO2 collection tube 13 within the CO2 collection lumen 12. When needed, the CO2 collection tube 13 can be inserted deep into the nasal cavity to monitor the patient's end-tidal CO2 non-invasively. The CO2 collection tube 13 is designed with a perforated structure or water-resistant and breathable material to reduce clogging. The invention has a simple structure, high clinical value, and strong practicality.

[0053] The above embodiments are merely illustrative of the principles and effects of this patent application and are not intended to limit this patent application. Any person skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of this patent application. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this patent application shall still be covered by the claims of this patent application.

Claims

1. A high-flow CO2 collection nasal oxygen cannula, comprising a nasal oxygen chamber (1) for supplying oxygen to the nasal cavity, a fixing strap (2) for fixing the nasal oxygen chamber (1) at the anterior position of the upper lip and nose, and a breathing connector (3) for connecting the nasal oxygen chamber (1) to the oxygen supply port of a high-flow humidified oxygen therapy device, wherein the nasal oxygen chamber (1) is connected to an intranasal tube (11) for supplying oxygen to the nasal cavity, characterized in that: The nasal oxygen chamber (1) is provided with a CO2 collection tube (12) corresponding to the position of the nostril; a CO2 collection tube (13) is adapted to be provided in the inner cavity of the CO2 collection tube (12); a CO2 collection interface (14) is provided at the tail end of the CO2 collection tube (13) extending out of the CO2 collection tube (12); the head end of the CO2 collection tube (13) extends through the CO2 collection tube (12) and enters the patient's nasal cavity.

2. The high-flow CO2 collection nasal cannula according to claim 1, characterized in that: The CO2 collection tube (12) is set in relation to the nasal tube (11). The head side of the CO2 collection tube (13) is movably enclosed in the CO2 collection tube (12) and the nasal tube (11). The CO2 collection tube (13) exits the CO2 collection tube (12) and extends into the patient's nasal cavity through the nasal tube (11).

3. The high-flow CO2 collection nasal cannula according to claim 1, characterized in that: The head end of the CO2 collection tube (13) is a hollow tube; Alternatively, the head end of the CO2 collection tube (13) may be made of a water-resistant and breathable material; Alternatively, the head end of the CO2 collection tube (13) is made into a hollow tube and covered with a water-resistant and breathable layer.

4. The high-flow nasal oxygen cannula for CO2 collection according to claim 1, characterized in that: The outer wall of the CO2 collection tube (13) is provided with a super-slippery coating; or, the CO2 collection tube (13) is made of a super-slippery material.

5. The high-flow nasal oxygen cannula for CO2 collection according to claim 1, characterized in that: The CO2 collection tube (13) has a limiting block (15) located 50-10 mm from the head end. The limiting block (15) is located outside the CO2 collection tube cavity (12) on the side away from the nasal oxygen cavity (1).

6. The high-flow nasal oxygen cannula for CO2 collection according to claim 1, characterized in that: A dryer (16) is connected to the CO2 collection tube (13), and water-absorbing particles are placed in the dryer.

7. The high-flow nasal oxygen cannula for CO2 collection according to claim 1, characterized in that: The CO2 collection tube (12) is provided with a matching perforated cap at the tail end, and a perforation adapted to the CO2 collection tube (13) is provided in the middle of the perforated cap; the tail end of the CO2 collection tube (12) is rotated and sealed, and a flexible gasket adapted to the CO2 collection tube (13) is provided at the bottom of the perforated cap; the CO2 collection tube (13) passes through the perforation of the perforated cap and the flexible gasket and enters the CO2 collection tube (12). Tighten the perforated cap to the tail end of the CO2 collection tube (12), and the flexible gasket is compressed and elastically deformed to clamp the CO2 collection tube (13); loosen the perforated cap to the tail end of the CO2 collection tube (12), the flexible gasket is restored, and the CO2 collection tube (13) is released.

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