A real-time respiratory airflow detection device for mouse tracheal intubation positioning

Abstract

The application belongs to the technical field of experimental animal medical devices, and particularly relates to a real-time respiratory airflow detection device for mouse tracheal intubation positioning, which comprises a main body detection unit, a sensor and a signal processing circuit arranged in the main body detection unit, and an airflow inlet and an airflow outlet arranged on the shell; an airflow conduction unit comprising an air inlet pipe and an air outlet pipe, one end of the air inlet pipe being communicated with the airflow inlet, one end of the air outlet pipe being communicated with the airflow outlet, and the other ends of the air inlet pipe and the air outlet pipe being used for jointly communicating with a retention cannula inserted into the trachea of a mouse; a signal display unit electrically connected with the main body detection unit and used for visually displaying the detected respiratory airflow signal; and a control and adjustment unit electrically connected with the signal processing circuit and used for adjusting a detection baseline and signal amplification sensitivity; the application can collect and display the respiratory airflow signal of a mouse, and can determine whether the retention cannula is accurately inserted into the trachea in real time and objectively while intubation, without relying on artificial experience observation.

Description

Technical Field

[0001] This invention relates to the field of laboratory animal medical device technology, specifically to a real-time respiratory airflow detection device for tracheal intubation positioning in mice. Background Technology

[0002] Mice, as a classic mammalian model, are widely used in biomedical experiments such as respiratory disease mechanism research, lung drug delivery validation, thoracic surgery model construction, and novel drug development due to their high reproductive capacity, high genetic similarity to humans, low breeding costs, and convenient model establishment. Endotracheal intubation is a core procedure in these mouse experiments; its accuracy, non-invasiveness, and efficiency directly determine the success rate of drug delivery, the reliability of experimental data, and also affect the survival rate of the mice and the overall progress of the experiment. However, the unique oral structure of mice, with their mandibles not fully open and the glottis opening not directly visible through the mouth, presents a significant technical challenge to the precise positioning of the endotracheal tube.

[0003] Currently, there are two main methods for tracheal intubation in mice: blind intubation and surgical tracheotomy. In blind intubation, the mouse is anesthetized, and the operator inserts the tube into the airway through the mouth based solely on touch and experience. Because the glottis cannot be directly observed, the success rate is highly dependent on the operator's skill, and accidental insertion into the esophagus is frequent. Repeated blind intubation can easily lead to airway mucosal edema, tearing, or even death. While surgical tracheotomy allows for visual intubation by exposing the trachea, the size of the incision, the control of aseptic technique, the degree of tissue damage, and the risk of postoperative infection all affect the mouse's recovery quality. Furthermore, mice cannot tolerate multiple tracheotomies, resulting in poor repeatability, making it particularly unsuitable for experiments requiring long-term observation or using valuable animal models. To address these issues, Chinese patent document CN121016034A discloses an auxiliary device for tracheal intubation in mice and rats. Its core component is an LED lamp with a 7mm outer diameter lamp head. The lamp wire can be bent and fixed arbitrarily, and the lamp holder is a clip for easy installation on the operating panel. During operation, the lamp head is placed on the mouse's neck. After turning on the light source, the ring of yellow light appearing inside the mouse's mouth indicates the location of the trachea. The intubation tube is then inserted along the center of the ring. However, this method still has significant shortcomings: the clarity of the light source marking is greatly affected by the thickness of the mouse's neck skin, the density of its fur, and the fit of the lamp head, making trachea location identification prone to errors. More importantly, this device only assists in the initial positioning before intubation and cannot verify the actual position of the indwelling cannula in real time after intubation. The intubation tube may still shift during insertion, and without a secondary confirmation step, it is impossible to effectively determine whether the intubation was truly successful.

[0004] In summary, current technologies, whether blind probing, surgical incision, or improved schemes based on external light sources, fail to utilize the objective physical signal of the mouse's own respiratory airflow for real-time, non-invasive verification of intubation position. Existing verification methods rely on manual visual judgment, tactile experience, or cursory chest observation, lacking objective criteria based on airflow signals. Incorrect intubation positions cannot be identified immediately and accurately, requiring manual re-instubation, significantly increasing experimental time, raising the probability of mouse injury, and reducing the success rate of tracheal instillation and ventilation experiments. Therefore, there is an urgent need for a detection device that can acquire real-time respiratory airflow signals from mice, objectively provide feedback on intubation position, and is easy to operate. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings and deficiencies of the existing technology and to provide a real-time respiratory airflow detection device for tracheal intubation positioning in mice. This real-time respiratory airflow detection device detects and displays the respiratory airflow signal of mice in real time, transforming the determination of intubation position from subjective experience to objective physical signal verification. This eliminates the uncertainty of traditional blind exploration and visual assistance schemes, effectively improves the accuracy of intubation and the success rate of experiments, and reduces animal injury.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A real-time respiratory airflow detection device for endotracheal intubation positioning in mice, comprising: The main detection unit contains sensors and signal processing circuits for detecting respiratory airflow, and the housing has an airflow inlet and an airflow outlet. An airflow conduction unit includes an inlet pipe and an outlet pipe. One end of the inlet pipe is connected to the airflow inlet, and one end of the outlet pipe is connected to the airflow outlet. The other ends of the inlet pipe and the outlet pipe are used to connect together to an indwelling cannula inserted into the trachea of ​​a mouse. A signal display unit is disposed on the surface of the main detection unit and electrically connected to the main detection unit for visually displaying the detected respiratory airflow signal; A control and adjustment unit, located on the main detection unit and electrically connected to the signal processing circuit, is used to adjust the detection baseline and signal amplification sensitivity; a power supply unit is also included. By using the objective physical signal of mouse respiratory airflow as the basis for determining the cannulation position, and combining electronic sensing with visualization, a fundamental shift from subjective experience-based judgment to objective signal verification is achieved. This eliminates the reliance on operator experience in traditional blind cannulation and visually assisted methods, providing a unified and objective physical standard for judging the success of cannulation. The dual-tube airflow circuit design ensures that both bidirectional respiratory airflow (exhalation and inhalation) of the mouse can be effectively collected, truly reflecting the respiratory state. The control and adjustment unit enables the device to have signal adaptability, capable of meeting the detection needs under different experimental conditions. The overall technical solution significantly improves the accuracy of cannulation and the success rate of experiments, reduces mouse injury caused by mis-cannulation, and enhances the repeatability and reliability of experiments.

[0007] In some embodiments, the signal display unit is a pointer-type analog meter, embedded in the top of the housing of the main detection unit, with a scale range of -3 to 3. Using a pointer-type analog meter as the signal display method offers advantages such as fast response speed and intuitive visual display. The -3 to 3 scale range allows the pointer to deflect bidirectionally, corresponding to the exhalation and inhalation phases respectively. The operator does not need to interpret numbers or waveforms; simply observing the rhythmic left-right swing of the pointer is sufficient to instantly determine whether intubation was successful. The meter is embedded in the top of the housing, providing an ergonomic viewing angle, allowing the operator to easily observe pointer changes while performing intubation. The analog display method avoids the reading delays and interpretation errors that may occur with digital displays, making it particularly suitable for periodic dynamic signals such as respiratory airflow, significantly reducing the operator's cognitive burden and improving experimental efficiency.

[0008] In some embodiments, the control adjustment unit includes a baseline adjustment knob located below the analog meter head for adjusting the pointer to zero. The baseline adjustment knob compensates for inherent tolerances of circuit components, changes in ambient temperature, and initial zero-point deviation of the sensor, ensuring precise zeroing of the pointer before each use. Zeroing calibration is a prerequisite for accurately determining the insertion position. If the pointer has a static offset, weak respiratory signals may be masked by the offset, leading to misjudgment. The baseline adjustment knob eliminates this source of error, ensuring the consistency of the detection device's output and the accuracy of its interpretation under different environmental conditions. The knob's location below the meter head shortens the operation path, facilitates calibration, and aligns with intuitive experimental logic.

[0009] In some embodiments, the control and adjustment unit further includes a gain adjustment lever, which is disposed on the side of the housing of the main detection unit and is used to switch between at least two signal amplification sensitivity levels. The gain adjustment lever changes the amplification factor of the signal processing circuit, enabling the device to adapt to the differences in respiratory airflow intensity among mice of different weights and depths of anesthesia. For smaller individuals or those under deeper anesthesia, the respiratory airflow is weak; if the gain is insufficient, the pointer swing amplitude will be too small to be observed. For larger individuals with strong respiration, if the gain is too high, the pointer may exceed its range and cannot be accurately read. With at least two gain switching functions, the operator can flexibly select the level according to the mouse's condition, effectively expanding the applicability of the device.

[0010] In some embodiments, the airflow conduction unit further includes a dual-tube transparent connector. The other ends of the inlet and outlet pipes are jointly inserted and fixed to the two interfaces of the dual-tube transparent connector. The other end of the dual-tube transparent connector is configured as a single interface for detachably and directly connecting to the tail end connector of the indwelling sleeve. The dual-tube transparent connector realizes the air path conversion and connection from the inlet and outlet pipes at one end to the single-interface indwelling sleeve at the other end. Functionally, it completes the airflow conduction transition between the dual-tube directional airflow circuit and the single-cavity indwelling sleeve. Structurally, it adopts a plug-in detachable connection, which can be directly connected to the indwelling sleeve used for conventional mouse tracheal infusion in the laboratory without modifying existing experimental consumables and operating procedures, and has strong compatibility. The transparent material makes it easy to observe whether there is condensation or foreign object blockage at the connection, ensuring unobstructed airflow. This design allows the detection device of the present invention to be seamlessly integrated into the existing laboratory workflow, reducing the threshold for use and the resistance to promotion.

[0011] In some embodiments, sealing rings are provided between the air inlet pipe and the airflow inlet, between the air outlet pipe and the airflow outlet, and at the connection points between the dual-tube transparent connector and each pipe, to ensure a sealed, detachable connection between the main detection unit, the airflow conduction unit, and the dual-tube transparent connector. The sealing rings ensure the airtightness of the entire airflow detection path, preventing external airflow interference and leakage of the detection airflow. Mouse respiratory airflow is weak; if there is a leak in the pipeline, the airflow signal strength will be significantly attenuated or even undetectable by the sensor, severely affecting detection sensitivity and judgment accuracy. If external airflow enters the path, it may generate interference signals, causing abnormal pointer swings and resulting in misjudgments. The sealing rings, while ensuring airtightness, employ a detachable connection method, facilitating the replacement of consumables and cleaning maintenance, thus balancing detection reliability and ease of use.

[0012] In some embodiments, the main detection unit is a rectangular sealed housing made of medical-grade hard aluminum, with metal screws securing the four corners of the housing. Medical-grade hard aluminum possesses excellent electromagnetic shielding properties, effectively suppressing the impact of electromagnetic interference in the environment on internal sensors and signal processing circuits, ensuring stable transmission and processing of weak electrical signals. The rectangular sealed housing structure provides physical protection for the internal precision electronic components, preventing liquid splashes or dust intrusion in the experimental environment from causing circuit failures. The detachable design with metal screws facilitates device inspection and maintenance, extending the device's service life. This structural design enables the device to operate stably for extended periods in complex experimental environments.

[0013] In some embodiments, both the inlet and outlet tubes are transparent silicone tubes. Transparent silicone tubes combine good flexibility and transparency. Flexibility allows the tubes to bend flexibly according to the mouse's position and the operator's gestures during operation, preventing kinking and blockage of the air passage; transparency allows the operator to visually observe whether condensation accumulates or foreign objects enter the tube, facilitating timely problem detection and cleaning maintenance; silicone material has good biocompatibility, is non-toxic and odorless, and is suitable for long-term use in laboratory environments. These characteristics collectively ensure the unobstructed flow and visibility of the airflow path, reducing maintenance costs during use.

[0014] In some embodiments, the power supply unit is connected to a 220V AC power source via a two-core power cord. A rocker switch is connected in series in the middle of the two-core power cord to control the power on and off of the device. Using a conventional 220V AC socket for power supply avoids the drawbacks of frequent battery replacements required by battery power, making it suitable for the needs of long-term, large-scale continuous experiments in laboratories. The rocker switch, located in the middle of the power cord, allows the operator to control the power on and off without touching the device body during experiments, ensuring safe and convenient operation. The switch is marked with ON / OFF indicators, making the device status clear at a glance and reducing the risk of misoperation. This power supply design enables the device to operate stably and continuously, meeting the continuity requirements of batch experiments.

[0015] In some embodiments, the main detection unit, airflow conduction unit, and signal display unit together constitute an airflow detection path. When the indwelling cannula is correctly inserted into the mouse's trachea, the mouse's respiratory airflow flows directionally through the airflow conduction unit to the sensor used to detect respiratory airflow, and the signal display unit generates a pointer swing synchronized with the respiratory rhythm. When the indwelling cannula is not correctly inserted into the trachea, no effective respiratory airflow enters the detection path, and the signal display unit does not swing its pointer. The criterion for determining the intubation position is clearly defined as whether there is a pointer swing synchronized with the respiratory rhythm, providing an objective, quantifiable, and reproducible criterion for determining whether intubation is successful. Unlike existing technologies that rely on subjective methods such as judging the amplitude of liquid surface fluctuations, visually estimating the number of bubbles, or auditory judging the intensity of sound, this invention achieves real-time closed-loop feedback—verification upon intubation and detection of incorrect intubation—through a binary judgment logic of pointer swing or no swing. This judgment logic is not affected by differences in operator experience, eliminating the subjective bias of human judgment. The intubation result can be accurately identified and reproduced by any operator, significantly improving the standardization of experiments and the efficiency of operational training. Meanwhile, the amplitude and frequency of the pointer swing can continuously reflect the respiratory status of the mouse, providing real-time monitoring for subsequent experimental operations and expanding the application value of the device.

[0016] The beneficial effects of this invention are: First, by detecting and displaying the respiratory airflow signal of mice in real time, the determination of the intubation position is transformed from subjective experience to objective physical signal verification, eliminating the uncertainty of traditional blind exploration and visual assistance methods, effectively improving the accuracy of intubation and the success rate of experiments, and reducing animal injury.

[0017] Secondly, the dual-tube structure and dual-tube transparent connector of the airflow conduction unit can be directly connected to the conventional indwelling cannula in the laboratory without modifying the existing operating procedures. The position can be verified immediately after insertion, and adjustments can be made immediately if the cannula is inserted incorrectly, avoiding mechanical damage to the airway caused by repeated operations, and improving the survival rate and service life of model animals.

[0018] Third, the baseline adjustment knob and gain adjustment lever are set up to accurately correct baseline drift and signal amplification, which can adapt to the weak respiratory airflow of mice of different weights and resist environmental vibration and airflow interference, ensuring the stability and reliability of the test.

[0019] Fourth, it adopts a modular sealed shell and a minimalist dual-tube connection structure, which does not come into direct contact with mice, making cleaning and maintenance simple, manufacturing costs low, and durability good, making it suitable for batch operation in the laboratory and long-term repeated use.

[0020] Fifth, non-invasive airflow detection replaces surgical incision, completely avoiding neck trauma and infection risks, simplifying the operation process, and is especially suitable for precious model animals such as gene knockout mice, effectively reducing the cost of experimental animals.

[0021] Sixth, the pointer-type analog meter, powered by a standard socket, allows operators to quickly determine the intubation status without interpreting complex data, meeting the needs of long-term batch experiments. A single person can independently complete the entire process of intubation positioning and drug administration, significantly improving operational convenience and experimental efficiency. Attached Figure Description

[0022] 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, obtaining other drawings based on these drawings without creative effort still falls within the scope of the present invention.

[0023] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the present invention; Figure 2 for Figure 1 Surface view of the main detection unit in the middle; Figure 3 This is a schematic diagram of the connection between the airflow conduction unit and the indwelling sleeve in an embodiment of the present invention; Figure 4 This is a block diagram showing the module connection of the signal processing circuit board according to an embodiment of the present invention. Detailed Implementation

[0024] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings, are intended to cover non-exclusive inclusion.

[0026] The directional and positional terms used in this invention, such as up, down, front, back, left, right, inside, outside, top, bottom, side, etc., are merely for reference to the accompanying drawings. Therefore, the directional and positional terms used are for illustrating and understanding this invention, and not for limiting the scope of protection of this invention.

[0027] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments: like Figures 1 to 3As shown, this embodiment provides a real-time respiratory airflow detection device for tracheal intubation positioning in mice, including a main detection unit 1, an airflow conduction unit 2, a signal display unit 3, a control and adjustment unit, a double-tube transparent connector 4, and a power supply unit 6.

[0028] The airflow conduction unit 2 consists of an inlet pipe 21 and an outlet pipe 22, both of which are transparent silicone tubes, offering good flexibility and facilitating observation of the airflow within the tubes. One end of the inlet pipe 21 is sealed and inserted into the airflow inlet 11, and one end of the outlet pipe 22 is sealed and inserted into the airflow outlet 12. The other ends of the inlet pipe 21 and the outlet pipe 22 are jointly inserted and fixed to the two interfaces of the double-tube transparent connector 4. The other end of the double-tube transparent connector 4 is configured as a single interface for detachable direct insertion into the tail end connector of the indwelling cannula 5 used for routine laboratory mouse tracheal infusion. All pipe connections, including the connection between the inlet pipe 21 and the airflow inlet 11, the connection between the outlet pipe 22 and the airflow outlet 12, and the connection between the double-tube transparent connector 4 and each pipe, are fitted with silicone sealing rings 41 to ensure the airtightness of the entire airflow detection pathway and prevent interference from external airflow.

[0029] The main detection unit 1 is a rectangular sealed housing 10 made of medical-grade hard aluminum, possessing excellent electromagnetic shielding and structural strength. The housing 10 is secured at its four corners with metal screws, facilitating easy disassembly and maintenance. The housing 10 integrates a high-sensitivity sensor 101 and a signal processing circuit board 100. In this embodiment, the sensor 101 is an MPX2010DP type piezoresistive silicon pressure sensor, with a differential pressure type, an operating pressure of 1.45 PSI (10 kPa), and an output of 0 mV to 25 mV (10V power supply). It features built-in temperature compensation and an operating temperature range of -40℃ to 125℃. This sensor is board-mounted, using a 4-SIP package, and has a double-barbed port, allowing simultaneous connection to the inlet pipe 21 and the outlet pipe 22. It indirectly reflects the magnitude and direction of airflow by detecting the dynamic pressure difference generated by the respiratory airflow. Its detection element is a Wheatstone bridge structure. When the mouse's respiratory airflow flows through the two ends of the sensor, the resulting dynamic pressure difference causes the bridge to output a differential voltage signal proportional to it.

[0030] The airflow channel inside the main detection unit 1 is designed as follows: the airflow inlet 11 is connected to one pressure port of the sensor 101, and the airflow outlet 12 is connected to the other pressure port of the sensor 101. The inlet pipe 21 and the outlet pipe 22 transmit the expiratory and inspiratory phase pressures of the mouse's respiratory airflow to both ends of the sensor 101, respectively. The polarity of the differential voltage output by the sensor 101 reverses as the airflow direction changes, thereby achieving bidirectional airflow detection. The response time of the sensor 101 is less than 1 millisecond (typical value), fully meeting the real-time detection requirements of mouse respiratory airflow. Figure 4As shown, the signal processing circuit board 100 integrates a preamplifier circuit, a baseline adjustment circuit, a gain switching circuit, and a drive circuit. Since the MPX2010DP piezoresistive silicon pressure sensor outputs a millivolt-level differential voltage, the preamplifier circuit uses a high common-mode rejection ratio instrumentation amplifier (such as INA118 or AD620) to amplify the differential signal to a level range capable of driving the analog pointer meter 31. The baseline adjustment circuit is electrically connected to the baseline adjustment knob 14, and achieves pointer zeroing calibration by adjusting the DC bias voltage of the input operational amplifier. The gain switching circuit is electrically connected to the gain adjustment lever 15, and switches at least two amplification levels by changing the resistance value connected in the feedback resistor network. The drive circuit outputs the processed signal to the analog pointer meter 31, driving the pointer to deflect left and right according to the airflow pressure difference signal. The housing 10 has an airflow inlet 11 and an airflow outlet 12 on its side, a signal display window 13 and a baseline adjustment knob 14 on its top surface, and a gain adjustment lever 15 on its left side. The signal display unit 3 is a pointer-type analog meter 31, which is embedded in the signal display window 13. The meter scale range is -3 to 3, and the pointer zero position is located in the center, which can deflect left and right with the input electrical signal.

[0031] The control and adjustment unit includes a baseline adjustment knob 14 (i.e., an offset adjustment knob) and a gain adjustment lever 15 (i.e., a gain adjustment lever). Both adjustment components are located on the main detection unit and are electrically connected to the internal signal processing circuit board 100, and are used to realize the detection baseline correction and signal amplification sensitivity adjustment functions, respectively.

[0032] The baseline adjustment knob 14 is a precision multi-turn potentiometer located below the signal display window 13. Its rotation axis is connected to the DC bias adjustment circuit on the internal signal processing circuit board 100. When the detection device is powered on but no mouse is connected, the pointer of the analog meter 31 may not accurately point to the "0" mark due to inherent tolerances of circuit components, changes in ambient temperature, and the initial zero-point deviation of the sensor. By rotating the baseline adjustment knob 14, the operator can change the DC bias voltage input to the non-inverting or inverting input of the operational amplifier in the signal processing circuit, thereby compensating for the static DC component of the sensor output and ensuring the pointer accurately returns to zero. The range of the baseline adjustment knob 14 is preferably set to compensate for zero-point drift of no more than ±10% of the full scale to ensure reliable zero-point calibration under different environmental conditions. After adjustment, the baseline setting value remains stable throughout the experiment and requires no repeated adjustments.

[0033] The gain adjustment lever 15 is a single-pole double-throw or single-pole triple-throw metal toggle switch, located on the side of the housing of the main detection unit 1. It switches the closed-loop gain of the operational amplifier by changing the input resistance value of the feedback resistor network in the signal processing circuit. In this embodiment, the gain adjustment lever 15 has two settings: a low setting (approximately 200x to 500x amplification) suitable for mice with large variations in respiratory airflow pressure (e.g., adult mice weighing more than 25g) or experimental scenarios requiring detailed observation of respiratory waveforms; and a high setting (approximately 1000x to 2000x amplification) suitable for small mice with weak respiratory airflow pressure (e.g., young mice weighing less than 20g or mice under deep anesthesia), increasing the signal amplification to a level where the pointer can swing noticeably. The gain adjustment lever 15 switches between settings by changing the mechanical position of the metal contacts, ensuring reliable contact and rapid switching. It allows for direct reading of airflow signals at different gains without the need for baseline recalibration.

[0034] The baseline adjustment knob 14 and gain adjustment lever 15 work together to enable the detection device of this invention to adapt to the differences in respiratory airflow intensity of mice with different weights and depths of anesthesia. In use, the operator first completes zeroing calibration using the baseline adjustment knob 14 without connecting a mouse, and then adjusts the gain adjustment lever 15 to the appropriate position according to the predicted weight of the mouse to be operated on. If the pointer swing amplitude is too small after intubation, making observation difficult, the gain adjustment lever 15 can be directly moved to a higher position without interrupting the experiment, eliminating the need for baseline recalibration. This convenient and efficient operation effectively ensures the stability and readability of the detection signal under various complex experimental conditions. The power supply unit 6 connects to 220V AC mains power via a two-core power cord 61, converting the AC power into the DC operating voltage required by the device. A rocker switch 62 is connected in series in the middle of the power cord, marked with ON / OFF, for easy power switching during the experiment.

[0035] The working process and principle of this invention are as follows: Before the experiment, connect the two-core power cord 61 of power supply unit 6 to a 220V AC power source and turn on the rocker switch 62 connected in series in the middle of the power cord to power on and preheat the device. When the device is first powered on, the pointer of the analog meter 31 will deviate from the maximum range position, i.e., the +3 mark, because the initial state of the circuit components is not stable. After the device has been powered on and preheated to a stable state, the operator slowly rotates the baseline adjustment knob 14 to change the DC bias voltage in the signal processing circuit, and accurately calibrates the meter pointer to the zero mark position on the dial, completing the instrument preheating and zero-point calibration. After calibration, the baseline setting value remained stable during this experiment.

[0036] It should be noted that the indwelling cannula 5 used for tracheal intubation in mice is a commercially available, general-purpose laboratory accessory and is not part of the components of this testing device. During the experiment, the operator first uses the standard blind tracheal intubation technique to independently insert the indwelling cannula 5 into the trachea of ​​the anesthetized mouse to complete the tracheal intubation operation.

[0037] After the intubation operation is completed, connect the single interface of the double-tube transparent connector 4 of the airflow conduction unit of this device to the vent interface at the tail end of the indwelling sleeve 5, so that the indwelling sleeve 5 forms a sealed communication channel with the air inlet pipe 21, air outlet pipe 22 and the internal air path of the main detection unit 1 of this device. At this time, the success of the intubation can be determined by observing the pointer status of the pointer analog meter 31, and the determination logic is as follows: If the indwelling cannula 5 is accurately positioned inside the mouse's trachea, the expiratory and inspiratory airflow generated by the mouse's breathing will produce periodic pressure fluctuations within the trachea. These pressure fluctuations are transmitted to the main detection unit 1 via the indwelling cannula 5 and the double-tube transparent connector 4. The two pressure ports of the MPX2010DP type piezoresistive silicon pressure sensor are connected to the inlet tube 21 and the outlet tube 22, respectively. The alternating direction of the respiratory airflow causes the differential pressure at both ends of the sensor to periodically alternate between positive and negative. The Wheatstone bridge inside the sensor outputs a millivolt-level voltage signal proportional to the differential pressure. This signal is amplified by an instrumentation amplifier, its gain is adjusted, and it is then processed to drive the pointer of the analog meter 31 to produce a regular reciprocating swing. During exhalation, the pointer deflects towards the negative value, and during inhalation, it deflects towards the positive value. The swing amplitude is positively correlated with the pressure change amplitude generated by the respiratory airflow, and the swing frequency is consistent with the mouse's respiratory rate. When the operator observes a clear swing of the pointer synchronized with the respiratory rhythm, it can be determined that the indwelling cannula has been accurately inserted into the trachea.

[0038] If the indwelling cannula 5 fails to enter the trachea, such as by mistake into the esophagus or remaining in the oral cavity, no effective periodic respiratory pressure fluctuations will enter the device. There will be no differential pressure change at the two ports of the sensor, and no periodic signal can be collected. The pointer of the analog meter 31 will remain stationary or only show weak, irregular fluctuations. In this case, the operator should disconnect the double-tube transparent connector 4 from the tail end of the indwelling cannula 5, remove the indwelling cannula, and repeat the mouse tracheal intubation procedure. Then, the double-tube transparent connector 4 should be reconnected to the tail end of the indwelling cannula for verification until a stable, rhythmic swing of the pointer is observed, confirming successful intubation.

[0039] Through the above operating procedure, this device uses the rhythmic swing of the pointer on the analog gauge 31 as an objective criterion for judgment, eliminating the need for operator tactile experience or chest wall observation. This enables rapid, intuitive, and objective verification of the placement of the endotracheal cannula in mice. After successful verification, the operator can continue to monitor the mouse's respiratory status in real time by observing the amplitude and frequency of the pointer swing, and then proceed with subsequent experimental procedures such as endotracheal instillation, drug administration, or mechanical ventilation.

[0040] To verify the technical effectiveness of the control and adjustment unit of this invention, six female C57BL / 6 mice (8-12 weeks old, weighing 19.5g-21.8g) were selected and intubated under the same depth of anesthesia. The pointer swing range was recorded when the gain adjustment lever was at the low and high positions. The results are shown in the table below: As shown in the table above, the average absolute swing amplitude of the pointer was 2.83 divisions at the low setting, with some smaller mice swinging only 2 divisions. After switching to the high setting, the average swing amplitude increased to 4.75 divisions, an increase of approximately 67.7%, and all individuals showed a clearly discernible swing. This result indicates that the gain adjustment lever can effectively amplify weak respiratory airflow signals, enabling mice of different weights to produce sufficient pointer deflection, facilitating quick and accurate judgment by the operator.

[0041] After the experiment, disconnect the double-tube transparent connector 4 from the indwelling sleeve 5, and clean the outer surface of the double-tube transparent connector by wiping it with an alcohol swab. The main body of the entire device does not come into direct contact with the mice, eliminating the need for frequent and complex disinfection, making it easy to maintain and suitable for large-scale continuous experiments.

[0042] The above description is merely a preferred embodiment of this application and is not intended to limit the scope of protection of this invention; the scope of protection of this invention is defined by the claims in the claims, and all equivalent changes and modifications made in accordance with this invention are within the scope of protection of this patent.

Claims

1. A real-time respiratory airflow detection device for endotracheal intubation positioning in mice, characterized in that: include: The main detection unit contains sensors and signal processing circuits for detecting respiratory airflow, and the housing has an airflow inlet and an airflow outlet. An airflow conduction unit includes an inlet pipe and an outlet pipe. One end of the inlet pipe is connected to the airflow inlet, and one end of the outlet pipe is connected to the airflow outlet. The other ends of the inlet pipe and the outlet pipe are used to connect together to an indwelling cannula inserted into the trachea of ​​a mouse. A signal display unit is disposed on the surface of the main detection unit and electrically connected to the main detection unit for visually displaying the detected respiratory airflow signal; A control and adjustment unit is disposed on the main detection unit and electrically connected to the signal processing circuit, used to adjust the detection baseline and signal amplification sensitivity; It also includes a power supply unit.

2. The real-time respiratory airflow detection device for endotracheal intubation positioning in mice according to claim 1, characterized in that: The signal display unit is a pointer-type analog meter, which is embedded in the top of the housing of the main detection unit, and its scale range is -3 to 3.

3. The real-time respiratory airflow detection device for endotracheal intubation positioning in mice according to claim 2, characterized in that: The control and adjustment unit includes a baseline adjustment knob, which is located below the pointer-type analog meter and is used to adjust the pointer to zero.

4. The real-time respiratory airflow detection device for endotracheal intubation positioning in mice according to claim 2 or 3, characterized in that: The control and adjustment unit also includes a gain adjustment lever, which is located on the side of the housing of the main detection unit and is used to switch between at least two signal amplification sensitivity levels.

5. The real-time respiratory airflow detection device for endotracheal intubation positioning in mice according to claim 1, characterized in that: The airflow conduction unit also includes a double-tube transparent connector. The other ends of the air inlet pipe and the air outlet pipe are jointly inserted and fixed to the two interfaces of the double-tube transparent connector. The other end of the double-tube transparent connector is set as a single interface for detachably and directly inserting into the tail end connector of the indwelling sleeve.

6. The real-time respiratory airflow detection device for endotracheal intubation positioning in mice according to claim 5, characterized in that: Sealing rings are provided between the air inlet pipe and the airflow inlet, between the air outlet pipe and the airflow outlet, and at the connection points between the double-tube transparent connector and each pipe to ensure a sealed, detachable connection between the main detection unit, the airflow conduction unit, and the double-tube transparent connector.

7. The real-time respiratory airflow detection device for endotracheal intubation positioning in mice according to claim 1, characterized in that: The main detection unit is a rectangular sealed shell made of medical-grade hard aluminum, with the four corners of the shell secured by metal screws.

8. The real-time respiratory airflow detection device for endotracheal intubation positioning in mice according to claim 1, characterized in that: Both the air inlet and outlet pipes are transparent silicone tubes.

9. The real-time respiratory airflow detection device for endotracheal intubation positioning in mice according to claim 1, characterized in that: The power supply unit is connected to a 220V AC power source via a two-core power cord. A rocker switch is connected in series in the middle of the two-core power cord to control the power on and off of the device.

10. The real-time respiratory airflow detection device for endotracheal intubation positioning in mice according to claim 1, characterized in that: The main detection unit, airflow conduction unit, and signal display unit together constitute the airflow detection path. When the indwelling cannula is correctly inserted into the mouse's trachea, the mouse's respiratory airflow flows directionally through the airflow conduction unit to the sensor used to detect respiratory airflow, and the signal display unit generates a pointer swing synchronized with the respiratory rhythm. When the indwelling cannula is not correctly inserted into the trachea, no effective respiratory airflow enters the detection path, and the signal display unit does not have the pointer swing.

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