Respiratory support equipment and end-expiratory CO2 detection method and device thereof

Abstract

The invention discloses respiratory support equipment and an end-expiratory CO2 detection method and device thereof. The device comprises a nasal catheter and a respiratory state sensing mechanism. The nasal catheter comprises a main machine pipeline connector connected with the main machine and a patient nasal connector in butt joint with the nasal cavity of a patient. The nasal catheter further comprises an air bag arranged in the nasal catheter and close to the nasal connector of the patient, the air bag is connected with an air bag control connector, and the air bag control connector is externally connected with an air bag driving unit. A CO2 detection connector is further arranged between the air bag and the patient nose connector and used for being connected with a CO2 detection unit to conduct gas sampling detection; the breathing state sensing mechanism comprises a flow sensor or a pressure sensor for detecting breathing airflow; wherein the inflation state or the deflation state of the air bag is switched according to a breathing phase determined by a detection signal of the flow sensor or the pressure sensor. The invention aims at improving the accuracy of detection data and effectively judging the real-time concentration of expired CO2.

Description

Technical Field

[0001] This invention relates to the field of respiratory equipment technology, and in particular to a respiratory support device and a method and apparatus for detecting end-tidal CO2. Background Technology

[0002] Respiratory therapy equipment mainly consists of a main unit, display, control circuit board, breathing tubing, humidifier, nasal cannula or mask, and other related components. When using high-flow oxygen therapy, respiratory support equipment requires a nasal cannula. However, the current design of nasal cannulas does not provide end-tidal CO2 detection or related devices. Because the nasal cannula's patient interface has a large leakage rate due to continuous flow, the high gas pressure during exhalation and the leakage of most of the exhaled CO2 gas lead to untimely and inaccurate end-tidal CO2 detection, thus failing to provide real-time data feedback.

[0003] Existing patent CN220237507U discloses a nasal oxygen tube, which includes a connector, an oxygen inhalation tube, a support, and an exhalation port. The connector includes a strip-shaped main body, an oxygen inhalation chamber and an exhalation chamber separated from each other within the main body, an oxygen inlet on the main body communicating with the oxygen inhalation chamber, and an air outlet on the main body communicating with the exhalation chamber. The oxygen inhalation tube is located on the connector and communicates with the oxygen inhalation chamber, and is inserted into one nostril. The support is located on the connector and is inserted into the other nostril. The exhalation port is located on the connector and communicates with the exhalation chamber, and is lower than the oxygen inhalation tube. This nasal oxygen tube, through physical isolation and positional design, directly reduces oxygen contamination and improves the basic accuracy of CO2 detection. However, while the narrowed exhalation port design reduces leakage, it does not solve the problem of interference during the inspiratory phase and cannot dynamically adjust the airway according to the respiratory phase (exhalation / inhalation). During inhalation, gas mixing may still occur due to the patient's breathing force or body position, and there is still a problem of continuous air leakage for high-flow oxygen therapy. Summary of the Invention

[0004] The main objective of this invention is to provide a respiratory support device and a method and apparatus for detecting end-tidal CO2, aiming to solve the problem that existing respiratory support devices cannot accurately detect end-tidal CO2.

[0005] To achieve the above objectives, the present invention provides an end-tidal CO2 detection device for a respiratory support device, the device comprising a nasal cannula and a respiratory status sensing mechanism;

[0006] The nasal cannula includes a host tubing interface connected to the host and a patient nasal interface that connects to the patient's nasal cavity.

[0007] The nasal cannula also includes an airbag disposed inside the nasal cannula and close to the patient's nasal inlet, the airbag and an airbag control interface, the airbag control interface being externally connected to an airbag drive unit;

[0008] A CO2 detection connection port is also provided between the airbag and the patient's nasal inlet for connecting a CO2 detection unit to perform gas sampling and detection.

[0009] The breathing state sensing mechanism includes a flow sensor or a pressure sensor for detecting respiratory airflow.

[0010] The inflation or deflation state of the airbag is switched according to the breathing phase determined by the detection signal of the flow sensor or pressure sensor.

[0011] Optionally, the airbag is an annular elastomer, the outer edge of which is sealed to the inner wall of the nasal cannula.

[0012] Optionally, the airbag control interface is connected to the airbag drive unit via a pneumatic pipeline, and the airbag drive unit is connected to the host electrical signal.

[0013] Optionally, the CO2 detection unit is electrically connected to the main unit, and the flow sensor or pressure sensor is located near the main unit's pipeline interface or in the gas path inside the main unit.

[0014] Optionally, the device further includes a headband for securing the nasal cannula body and a clamp for adjusting the position of the tubing.

[0015] Furthermore, to achieve the above objectives, the present invention also provides a method for detecting end-tidal CO2 in a respiratory support device, the method being applied to the end-tidal CO2 detection device described in any of the above claims, comprising the following steps:

[0016] Step 1: Detect the patient's respiratory status using sensors to determine the expiratory or inspiratory phase;

[0017] Step 2: When the exhalation phase is detected, the air bag (3) in the nasal cannula is opened, and the CO2 detection unit is started again;

[0018] Step 3: When the inhalation phase is detected, the control airbag (3) is closed and CO2 detection is paused.

[0019] Optionally, the expiratory or inspiratory phase can be determined by monitoring changes in gas flow direction and / or flow rate using a flow sensor located on the breathing tubing or nasal cannula; or, the expiratory or inspiratory phase can be determined by detecting changes in airway pressure using a pressure sensor located on the breathing tubing or nasal cannula.

[0020] Optionally, the real-time signal detected by the sensor is compared with a preset threshold; when the signal value exceeds the preset exhalation threshold, it is determined that the exhalation phase has started; when the signal value is lower than the preset inhalation threshold, it is determined that the inhalation phase has started.

[0021] In addition, to achieve the above objectives, a respiratory support device is provided, the device comprising a main unit, a fan, a humidifier and a breathing tubing, characterized in that the device further integrates the aforementioned end-tidal CO2 detection device and a control system configured to perform the method as described above.

[0022] In addition, to achieve the above objectives, the present invention also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the end-tidal CO2 detection method as described above.

[0023] Beneficial effects:

[0024] (1) By actively isolating the airbag during the expiratory phase, the working state of continuous leakage of traditional nasal cannulas is fundamentally changed, enabling the CO2 detection unit to obtain pure alveolar gas samples that are not diluted by the main unit's airflow, thus completely solving the problem of inaccurate detection caused by leakage. In addition, the added airbag and detection interface have a simple structure, requiring no complex modification to the respiratory support main unit, and are easy to integrate and implement on existing product platforms.

[0025] (2) The entire detection process of this invention is automatically controlled by the host, eliminating the need for medical personnel to manually switch modes or perform complex operations. It also obtains accurate, real-time respiratory signals and EtCO2 data, providing an indispensable foundation for the future development of more advanced intelligent treatment modes. It enables automatic adjustment of ventilator parameters based on the target EtCO2 value, forming a true closed-loop feedback system. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0027] Figure 1 A schematic diagram of the nasal cannula with the airbag in the deployed state;

[0028] Figure 2 for Figure 1 Enlarged view of the central airbag in the deployed state;

[0029] Figure 3 This is a schematic diagram of the nasal cannula with the airbag closed.

[0030] Figure 4 for Figure 2 Enlarged view of the central airbag in the closed state;

[0031] Figure 5 This is a block diagram of a respiratory support device.

[0032] Figure 6 This is an electrical connection diagram for a respiratory support device.

[0033] Explanation of icon numbers:

[0034] 1-Main unit tubing interface, 2-Fixing strap, 3-Insufflé, 4-Patient nasal interface, 5-Fixing clip, 6-Insufflé control interface, 7-CO2 detection connection port, 8-Fixing headband.

[0035] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0036] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0037] See Figure 1-6 This invention provides a schematic diagram of an embodiment of an end-tidal CO2 detection device for a respiratory support system. The device includes a nasal cannula and a respiratory status sensing mechanism. The main body of the nasal cannula is made of medical-grade silicone tubing, possessing good biocompatibility and flexibility. One end of the tubing is connected to the main unit of the respiratory support system via a main unit tubing interface 1, and the other end branches into two branches, forming a patient nasal interface 4. Inside the tubing, approximately 5 cm from the patient nasal interface 4, an airbag 3 is positioned. This airbag has a ring-shaped structure, and its edge is sealed and fixed to the inner wall of the tubing with medical-grade adhesive. The airbag material is made of highly elastic rubber, which, when inflated, can completely block the tubing channel. Figure 1-2 The airbag shown is in the deployed state. Figure 3-4 The airbag is in the closed position.

[0038] Furthermore, the airbag 3 is connected to the outside via the airbag control interface 6, which is a miniature tube passing through the wall of the flexible tube, preferably with an outer diameter of 2 mm; and the airbag control interface 6 is connected to the airbag drive unit via a pneumatic tube, the airbag drive unit being connected to the host electrical signal, and the pneumatic tube is preferably a flexible thin tube.

[0039] Furthermore, a CO2 detection connection port 7 is provided on the wall of the flexible tube on the patient side of the airbag 3. This port is connected to an external CO2 detection unit via another thin tube for collecting gas samples. The CO2 detection unit is also connected to the main unit via electrical signals.

[0040] Furthermore, the nasal cannula is also equipped with a head strap 8 and a clamp 5 for securing the cannula to the patient's head. A fixation band 2 is also provided to further secure the tubing.

[0041] Furthermore, the breathing state sensing mechanism includes a flow sensor or pressure sensor for detecting breathing airflow. The flow sensor or pressure sensor is located near the main unit pipeline interface 1 or in the air path inside the main unit. The flow sensor or pressure sensor is also connected to the main unit electrical signal.

[0042] Furthermore, the inflation or deflation state of the airbag 3 is switched according to the respiratory phase determined by the detection signal of the flow sensor or pressure sensor. Specifically, during the exhalation phase, it inflates to block the exhaled gas from flowing to the main unit pipeline interface 1, allowing the exhaled gas to be detected via the CO2 detection connection port 7; during the inhalation phase, it deflates to restore the gas supply from the main unit to the patient.

[0043] Furthermore, the host includes an MCU, which uses an STM32 series chip, and connects to a flow sensor and a pressure sensor via an I2C interface. The sensors are installed in the breathing tubing near the host outlet.

[0044] Furthermore, the MCU's GPIO pins are connected to the airbag driving module via a driver circuit. This module contains a small solenoid valve and a miniature air pump. The solenoid valve controls the on / off state of the air supply, and the air pump provides positive / negative pressure.

[0045] Furthermore, the CO2 detection unit uses a mainstream infrared sensor and communicates with the MCU via a UART interface to transmit CO2 concentration data in real time.

[0046] Furthermore, the present invention also provides a method for detecting end-tidal CO2 in a respiratory support device, the method being applied to the end-tidal CO2 detection device described in any of the above claims, comprising the following steps:

[0047] Step 1: System initialization. After the device is powered on, the MCU initializes each peripheral module, the airbag drive module sets the internal airbag 3 to the closed state, and the CO2 detection unit preheats for about 30 seconds.

[0048] Step 2: Respiratory status monitoring. The flow sensor continuously monitors the gas flow rate in the breathing tubing. When the flow rate is positive (flowing towards the patient), it is determined to be the inspiratory phase; when the flow rate turns negative (flowing towards the main unit) or the pressure sensor detects a significant increase in pressure, it is determined to be the start of the expiratory phase.

[0049] Step 3: Expiratory phase processing. When the start of exhalation is detected, the MCU performs the following operations: (1) Sends a command to the airbag drive module, the solenoid valve opens, and the air pump generates positive pressure (about 20 kPa); (2) The pressure is transmitted to the internal airbag 3 through the airbag control interface 6, so that it fully inflates within 150 ms; (3) After the airbag 3 inflates, it blocks the airway to the host, and the exhaled gas is restricted to the patient end; (4) After a delay of 50 ms, the CO2 detection unit is started to sample.

[0050] Step 4: CO2 concentration detection. Exhaled gas enters the detection unit through CO2 detection port 7. The sensor samples once every 100ms, and the data is sent to the MCU through the serial port.

[0051] The MCU performs digital filtering (Kalman filtering) on ​​the collected CO2 concentration data to identify the plateau phase of the concentration curve. The concentration value corresponding to this plateau phase is the end-tidal CO2 value (EtCO2).

[0052] Step 5: Inhalation phase processing. When the flow sensor detects that the flow rate has turned positive again, it determines that exhalation has ended. The MCU executes: (1) Stop the CO2 detection unit from sampling; (2) Control the airbag drive module, switch the solenoid valve, and generate negative pressure in the air pump so that the airbag 3 is fully contracted within 100ms; (3) Restore normal breathing gas delivery.

[0053] The entire testing process is automatically controlled by the host system, eliminating the need for medical staff to manually switch modes or perform complex operations. The MCU automatically identifies the respiratory phase, controls the cuff movement, and performs detection and data analysis. Furthermore, the MCU's judgment and response speed for respiratory phase is extremely fast (millisecond level), enabling the entire process of "detection-analysis-display" to be completed within each of the patient's respiratory cycles. This allows medical staff to continuously and dynamically observe changes in the patient's ventilation function, rather than relying on continuous or delayed sampling examinations, providing crucial technical support for the timely detection of changes in the patient's condition.

[0054] Step 6: Data Processing and Display. The EtCO2 value calculated by the MCU is displayed in real time on the host monitor, and a CO2 waveform graph is plotted simultaneously. When the EtCO2 value exceeds the preset safe range (35-45 mmHg), an audible and visual alarm is triggered. Accurate EtCO2 data is one of the gold standards for assessing pulmonary ventilation and gas exchange function. This invention makes it possible to continuously monitor EtCO2 during high-flow oxygen therapy. It allows doctors to objectively and quantitatively assess the effectiveness of oxygen therapy based on dynamic EtCO2 trends and adjust parameters such as flow rate and oxygen concentration in a timely manner, achieving individualized and precise treatment and fulfilling the goal of "promptly informing users to improve respiratory treatment methods." Furthermore, by setting an EtCO2 safe range, an alarm can be immediately issued if an abnormally high value is detected (potentially indicating insufficient ventilation) or an abnormally low value is detected (potentially indicating pulmonary embolism, decreased cardiac output, etc.). This has bought valuable time for rescuing critically ill patients, and achieved the goal of "providing effective and timely treatment basis for adjusting treatment plans and finding the causes of abnormally high or low end-tidal CO2 levels", ultimately serving the fundamental goal of "reducing patient pain and reducing the risk of further disease progression".

[0055] Furthermore, it also includes the following special processing logic:

[0056] Apnea detection: If no effective breathing is detected for more than 10 seconds, the system will automatically keep the airbag closed to ensure a continuous supply of oxygen and issue an alarm.

[0057] Cough handling: When a brief pressure spike is detected, the system recognizes it as a cough and does not perform a phase switch to avoid accidental operation.

[0058] Equipment self-test: Each time the system is started, it automatically checks the airbag sealing and sensor status to ensure detection accuracy.

[0059] The main technical indicators achieved by the implementation method are as follows:

[0060] EtCO2 detection error: ≤±2mmHg;

[0061] Response time: <400ms from the start of exhalation to the display of results;

[0062] Detection range: 0-100 mmHg;

[0063] Operating flow rate range: 5-60L / min;

[0064] Airbag operational lifespan: >100,000 cycles.

[0065] Furthermore, the present invention also provides a respiratory support device, such as... Figure 5-6As shown, the device includes a main unit, a fan, a humidifier, and a breathing tubing. The device also integrates the aforementioned end-tidal CO2 detection device and a control system configured to perform the methods described above. The fan within the main unit serves as the primary gas input power source for the breathing device, mixing oxygen and air and delivering it to the patient for oxygen therapy support when oxygen support is required.

[0066] The control system includes an MCU, an airbag drive module, a CO2 detection unit, and a flow sensor or a pressure sensor. The MCU is configured to receive input signals from the flow sensor or pressure sensor to determine whether the patient is in an exhalation or inhalation state. Specifically, in the exhalation state, the MCU controls the airbag drive module to close the controllable airbag 3 and activates the CO2 detection unit for data acquisition. In the inhalation state, the MCU controls the airbag drive module to open the controllable airbag 3 and disables the CO2 detection unit.

[0067] exist Figure 6 In the diagram, the part within the dashed box serves as the main component for gas heating and humidification. The humidifier is connected in series in the breathing tubing, and the temperature sensor is located inside the breathing tubing or on the humidifier. The temperature sensor installed inside the humidifier / breathing tubing feeds back the temperature to the MCU, thereby adjusting the temperature of the humidifier / breathing tubing in real time through the drive unit.

[0068] The nasal cannula's cuff is controlled by an MCU-controlled cuff drive module to generate or release cuff gas pressure, thus opening or closing the cuff. The main MCU uses flow or pressure sensors to determine the patient's inhalation or exhalation status. The CO2 detection unit sends the gas concentration within the nasal cannula to the MCU.

[0069] In addition, flow / pressure sensors are used to detect changes in gas flow or pressure in the breathing tubing in real time and convert these physical signals into electrical signals, which are then provided to the MCU for decision-making.

[0070] The drive unit receives low-voltage control signals from the MCU and converts them into high-voltage power to drive the fan motor. The fan module unit, acting as a pneumatic source, rotates according to the received instructions, generating gas at the required flow rate and pressure for treatment.

[0071] The system includes an LCD screen and button unit to provide a human-machine interface. This displays respiratory parameters, CO2 waveforms, alarm information, and allows users to set parameters. The memory unit stores device settings, treatment data, trend waveforms, and event logs. The interface unit provides external communication interfaces (such as USB or network) for data transmission, software upgrades, or connection to a central monitoring system.

[0072] The device also includes an alarm unit electrically connected to the main control unit (MCU); the main control unit (MCU) is further configured to control the alarm unit to issue a warning signal when the concentration value output by the CO2 detection unit continuously exceeds a preset safety range.

[0073] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. An apparatus for end-tidal CO2 detection of a respiratory support device, characterized in that, The device comprises a nasal catheter and a breathing state sensing mechanism; The nasal catheter comprises a host pipeline interface (1) connected with a host and a patient nose interface (4) connected with a patient's nasal cavity; The nasal catheter further comprises an airbag (3) arranged inside the nasal catheter and close to the patient nose interface (4), the airbag (3) is connected with an airbag control interface (6) which is connected with an airbag driving unit; A CO2 detection connecting port (7) is arranged between the airbag (3) and the patient nose interface (4) for connecting a CO2 detection unit to conduct gas sampling detection; The breathing state sensing mechanism comprises a flow sensor or a pressure sensor for detecting respiratory airflow; The inflation or deflation state of the airbag (3) is switched according to the respiratory phase determined by the detection signal of the flow sensor or the pressure sensor.

2. The apparatus of claim 1, wherein, The airbag (3) is a ring-shaped elastic body, and the outer edge thereof is sealingly connected with the inner wall of the nasal catheter.

3. The apparatus of claim 2, wherein, The airbag control interface (6) is connected with the airbag driving unit through a pneumatic pipeline, and the airbag driving unit is connected with the host electric signal.

4. The apparatus of claim 2, wherein, The CO2 detection unit is connected with the host electric signal, and the flow sensor or the pressure sensor is arranged in the gas path near the host pipeline interface (1) or in the host.

5. The apparatus of any one of claims 1 to 4, wherein, The device further comprises a fixing headband (8) for fixing the body of the nasal catheter and a fixing clamp (5) for adjusting the position of the pipeline.

6. A method of end-tidal CO2 detection for a respiratory support device, the method comprising: The method is applied to the end-tidal CO2 detection device of any one of claims 1-5, comprising the following steps: Step 1: detecting the breathing state of the patient through the sensor to determine the expiration phase or the inspiration phase; Step 2: when the expiration phase is detected, the airbag (3) in the nasal catheter is opened, and the CO2 detection unit is started; Step 3: when the inspiration phase is detected, the airbag (3) is closed, and the CO2 detection is paused.

7. The method of claim 6, wherein, The expiration or inspiration phase is determined by monitoring the change of gas flow direction and / or flow value through the flow sensor arranged on the breathing pipeline or the nasal catheter, or by detecting the change of airway pressure through the pressure sensor arranged on the breathing pipeline or the nasal catheter.

8. The method of claim 7, wherein, The real-time signal detected by the sensor is compared with the preset threshold value; when the signal value exceeds the preset expiration threshold value, it is determined that the expiration phase starts; when the signal value is lower than the preset inspiration threshold value, it is determined that the inspiration phase starts.

9. A respiratory support apparatus, the apparatus comprising a host computer, a blower, a humidifier and respiratory tubing, characterised in that, The device further integrates the end-tidal CO2 detection device of any one of claims 1-5, and a control system configured to perform the method of any one of claims 6-8.

10. A computer-readable storage medium, characterized in that, The medium stores a computer program, and the computer program is executed by a processor to realize the end-tidal CO2 detection method of any one of claims 6-8.

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