Breath-synchronized extracorporeal phrenic nerve electrical pulse stimulator

Abstract

The application discloses a kind of respiratory synchronous extracorporeal diaphragm nerve electric stimulator, belong to medical equipment technical field, to solve the problem of low diaphragm muscle contraction efficiency and patient discomfort caused by electric stimulation and patient inhalation action asynchronization in respirator treatment.The device detects the inspiratory flow rate signal in real time by accessing the flow rate sensor at the patient end of the respirator circuit, and transmits it to the control unit after amplification and filtering by the signal conditioning circuit;The control unit determines whether the inspiratory flow rate meets the standard based on the preset threshold, and synchronously triggers the electric stimulation module to output pulse signals matching the respirator inspiration cycle to the diaphragm nerve.The core of its technical scheme includes dynamic detection of flow rate signal, threshold determination logic and adaptive adjustment of electric stimulation pulse envelope length, to ensure that electric stimulation is accurately synchronized with the inspiration phase.The device is mainly used to assist respirator users in enhancing diaphragm nerve driving ability and improving ventilation and blood flow ratio imbalance, and is suitable for rehabilitation treatment of patients with chronic respiratory failure or diaphragm dysfunction.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of medical equipment, and particularly relates to a breathing-synchronous extracorporeal diaphragm nerve electric stimulator. BACKGROUND

[0002] In ventilator-assisted treatment, extracorporeal diaphragm nerve electric stimulation technology is often used to improve the ventilation efficiency of patients with diaphragm dysfunction. However, the synchronization of the electric stimulation with the actual inspiration action of the patient in the prior art still has significant deficiencies. The traditional stimulation trigger mechanism is mostly based on the preset timing of the ventilator or the indirect detection of the chest movement of the patient, and it is difficult to accurately capture the dynamic characteristics of the inspiration starting stage. For example, some devices rely on the fixed timing signal output by the ventilator to trigger electric stimulation, but due to the individual differences between the patient's spontaneous breathing and the ventilator support mode, such a method is easy to cause the stimulation pulse to be misaligned with the real inspiration stage. Studies have shown that a timing deviation of more than 100 ms can significantly reduce the diaphragm contraction efficiency, and even cause the antagonistic contraction of the inspiratory muscle and the electric stimulation, and aggravate the discomfort of the patient.

[0003] In the prior art, the detection of the inspiration flow rate signal often has a contradiction between sensitivity and anti-interference ability. Some devices use a flow rate sensor away from the patient end (such as the outlet of the ventilator), which causes signal delay or attenuation, especially when the pipeline is long or there is condensate water, the detection error is further increased. In addition, the airflow noise in the breathing pipeline, pressure fluctuations, and patient coughing and other actions interfere, making it particularly difficult to extract the signal in the low-speed inspiration stage. Conventional filtering algorithms (such as low-pass filters with fixed cutoff frequencies) are difficult to effectively distinguish between real inspiration flow rate and noise, and are easy to cause baseline drift or high-frequency interference residues, affecting the accuracy of threshold determination. Experimental data shows that when the inspiration flow rate is lower than 5 L / min, the false trigger rate can reach more than 20%, which seriously restricts the accuracy of the stimulation timing.

[0004] The rigidity of the threshold determination logic is another key problem. The existing systems mostly use a fixed flow rate threshold (such as a constant 5 L / min) as the trigger condition, but the inspiration flow rate fluctuation caused by the disease state, ventilator parameter setting or body position change of the patient often exceeds the preset range. For example, the peak inspiration flow rate of a patient with chronic obstructive pulmonary disease may be only 30% of that of a healthy individual, and a patient with acute respiratory distress syndrome presents the characteristics of high flow rate and short inspiration time. The fixed threshold cannot dynamically adapt to such differences, resulting in the stimulation being triggered too early or too late. In addition, the traditional determination logic lacks analysis of the dynamic characteristics (such as the rising slope) of the signal, and only relies on single-point threshold comparison, which is easy to make false judgments due to instantaneous noise. This problem is particularly prominent in non-invasive ventilation or in the presence of air leakage, causing the synchronization rate of the stimulation pulse and the real inspiration action to decrease.

[0005] The lack of matching of the stimulation pulse parameters with the respiratory cycle further limits the treatment effect. Some devices set the electrical stimulation duration as a fixed value, or only roughly synchronize according to the preset inspiration cycle of the ventilator, but the actual inspiration duration is affected by factors such as patient effort, airway resistance, and can deviate from the preset value by 10%-30%. For example, in the pressure support mode, the ventilator can adjust the gas delivery time in real time according to the patient's inspiration effort, while the traditional stimulator lacks a dynamic tracking mechanism, so its pulse envelope cannot be adjusted accordingly, resulting in overlap between the late stimulation and the end of inspiration, which can inhibit the patient's spontaneous expiration or cause diaphragmatic fatigue. In addition, the existing technology rarely considers emergency synchronization strategies when the ventilator communication is interrupted (such as interface failure or compatibility problems). Once the ventilator timing signal is lost, the electrical stimulation will completely lose synchronization, which poses a clinical risk.

[0006] The root cause of the above problems lies in the lack of real-time, anti-interference, and dynamic adaptive mechanisms in respiratory signal detection. Developing a synchronization system that can accurately identify the start point of low-speed inspiration, dynamically adjust the decision threshold, and real-time match with the respiratory cycle needs to overcome technical difficulties such as multi-physical signal coupling interference, individualized respiratory mode differences, and hardware response delay. For example, how to complete signal acquisition, processing, and decision-making within a millisecond-level time window while avoiding computational resource overload; how to design a robust signal processing algorithm to distinguish between real inspiration flow rate and pipeline vibration noise; and how to maintain synchronization accuracy through alternative signals (such as nasal negative pressure) when there is no ventilator timing support, are all bottlenecks that need to be broken through to achieve efficient synchronization. SUMMARY

[0007] One object of the present application is to solve the problem that the conventional extracorporeal diaphragmatic nerve electrical stimulator relies on the preset timing of the ventilator or indirectly triggers electrical stimulation by the signal, which is difficult to accurately match the actual inspiration stage of the patient, resulting in poor synchronization, low diaphragmatic contraction efficiency, and patient discomfort.

[0008] Solve the problem that the electrical stimulation module is mis-triggered during the expiration cycle or continuously output during the low flow rate stage, which may interfere with the patient's spontaneous breathing, cause diaphragmatic fatigue or antagonistic contraction.

[0009] Solve the problem that the signal conditioning circuit has insufficient processing capacity for the inspiration flow rate signal, baseline drift, and high-frequency noise residue, which leads to threshold determination errors and affects the triggering accuracy.

[0010] Solve the problem that the single flow rate signal triggering mechanism is easily affected by air pressure fluctuations or transient interference, resulting in high mis-triggering rate, and multiple signals need to be used to improve reliability.

[0011] Solve the problem that the timing signal analysis lacks a dynamic window mechanism, which cannot exclude transient noise interference, resulting in mis-triggering or missed triggering.

[0012] The gain and filter parameters of the signal conditioning circuit are fixed, and it is difficult to adapt to the signal amplitude-frequency characteristic difference of different patients or breathing modes.

[0013] The fixed threshold determination logic cannot be dynamically calibrated, and the patient's inhalation flow rate fluctuation or environmental interference easily leads to misjudgment, and the synchronization rate decreases.

[0014] The electric stimulation parameters are not dynamically related to the inhalation flow rate, and the intensity and frequency cannot be adjusted according to the real-time requirements of the patient, so that the treatment effect is limited.

[0015] The electric stimulation envelope length is rigidly bound to the ventilator inhalation cycle, and cannot adapt to the dynamic change of the actual inhalation time, resulting in the overlap of the stimulation later period and the exhalation.

[0016] When the ventilator signal is lost, there is no backup synchronization mechanism, and the electric stimulation is completely out of synchronization, which has clinical risk.

[0017] The present application provides a kind of respiratory synchronous extracorporeal diaphragm nerve electric stimulator, comprising:

[0018] Flow rate sensor, access to ventilator pipeline near patient end, for real-time detection of inhalation flow rate signal;

[0019] Signal conditioning circuit, connected with the flow rate sensor, including operational amplifier and filter module, for amplifying and filtering processing to inhalation flow rate signal;

[0020] Control unit has analog-digital conversion interface, receives the inhalation flow rate signal after conditioning, and detects whether the inhalation flow rate reaches preset threshold Vh in real time;

[0021] Electric stimulation module, connected with the control unit, when the inhalation flow rate reaches or exceeds Vh, output electric stimulation pulse to diaphragm nerve;

[0022] The envelope length of the electric stimulation pulse is less than or equal to the inhalation time set by the ventilator, or automatically matches the inhalation cycle of the ventilator.

[0023] Preferably, the control unit of the respiratory synchronous extracorporeal diaphragm nerve electric stimulator of the present application stops electric stimulation when the inhalation flow rate is less than 20% of the peak flow rate Vpeak;

[0024] Electric stimulation pulse is only triggered in inhalation cycle, and is prohibited to output in exhalation cycle;

[0025] The flow rate sensor is connected with the ventilator pipeline through a three-way interface, and the installation position is less than 10cm away from the patient end interface.

[0026] Preferably, the filter module of the signal conditioning circuit of the respiratory synchronous extracorporeal diaphragm nerve electric stimulator of the present application is a band-pass filter, and the cutoff frequency range is 0.1Hz to 10Hz.

[0027] The pulse waveform output by the electric stimulation module includes a positive-negative biphasic pulse, with a pulse width of 0.1 ms to 1 ms, a frequency of 10 Hz to 50 Hz, and a current intensity of 5 mA to 30 mA.

[0028] Preferably, the respiratory-synchronized extracorporeal diaphragm nerve electric stimulator of the present application further comprises:

[0029] The air pressure sensor is arranged near the airway interface of the ventilator pipeline and is connected to the control unit, and is used to detect the air pressure signal in the ventilator pipeline in real time; the control unit is further configured to synchronously analyze the inspiratory flow rate signal and the air pressure signal, and trigger the electric stimulation module to output a pulse when the inspiratory flow rate signal exceeds a preset threshold Q and the air pressure signal meets a triggering condition.

[0030] Preferably, the control unit of the respiratory-synchronized extracorporeal diaphragm nerve electric stimulator of the present application is configured to analyze the inspiratory flow rate signal and the air pressure signal through a time window synchronization mechanism, specifically including:

[0031] When the inspiratory flow rate signal is detected to exceed the threshold Q, a time window T of 50 ms to 200 ms is started;

[0032] If the air pressure signal is simultaneously detected to be lower than a preset threshold Ph and the waveform slope is ≥S (0.2 Pa / ms to 0.5 Pa / ms) within the window T, the electric stimulation pulse is triggered;

[0033] If only a single signal meets the criteria within the window T, it is determined as an invalid trigger and the output is shielded.

[0034] Preferably, the respiratory-synchronized extracorporeal diaphragm nerve electric stimulator of the present application, the operational amplifier is configured to amplify the inspiratory flow rate signal, and the gain is adjustable in the range of 10 to 100 times;

[0035] The filter module includes two-stage filtering: the first stage is a high-pass filter with a cutoff frequency of 0.1 Hz to 10 Hz, used to eliminate baseline drift; the second stage is a low-pass filter with a cutoff frequency of 20 Hz to 100 Hz, used to filter out high-frequency noise;

[0036] The output end of the signal conditioning circuit is connected to the ADC module of the control unit, and the processed inspiratory flow rate signal is transmitted.

[0037] Preferably, the control unit of the respiratory-synchronized extracorporeal diaphragm nerve electric stimulator of the present application is configured to receive the conditioned inspiratory flow rate signal through an analog-to-digital conversion interface, and detect in real time whether the inspiratory flow rate reaches a preset threshold Vh=5 L / min;

[0038] The sampling frequency of the analog-digital conversion interface is 200 Hz to 1 kHz, the resolution is ≥12 bits, and the input voltage range covers -5 V to +5 V.

[0039] The real-time detection logic comprises:

[0040] In the next 3 sampling periods, if the average value of the inspiratory flow rate signal ≥Vh and the rising slope ≥2 L / min², it is determined as a valid inspiratory trigger;

[0041] When the inspiratory flow rate signal fluctuates more than 50% of Vh within 1 s, the dynamic threshold calibration is started, and Vh is adjusted to 30% to 70% of the current flow rate peak value.

[0042] Preferably, the electrical stimulation module of the respiratory-synchronized extracorporeal diaphragm nerve electrical stimulator of the application is configured to output a dynamic adjustment electrical stimulation pulse linked with the real-time inspiratory flow rate to the diaphragm nerve when the inspiratory flow rate reaches or exceeds Vh;

[0043] The current intensity of the electrical stimulation pulse is dynamically adjusted according to the difference between the real-time inspiratory flow rate and the threshold Vh, and the current intensity increases by 0.5 mA to 2 mA for each 1 L / min increase in the difference, the initial current intensity is 5 mA to 10 mA, and the maximum current intensity does not exceed 30 mA;

[0044] The frequency of the electrical stimulation pulse is adjusted in stages according to the real-time inspiratory flow rate, and when the inspiratory flow rate reaches or exceeds 2 times Vh, the frequency is increased to 50 Hz; and when the inspiratory flow rate is lower than Vh, the frequency is reduced to 10 Hz;

[0045] The electrical stimulation module is built-in with an independent safety monitoring circuit, which immediately cuts off the output and triggers an audible and light alarm when the real-time inspiratory flow rate continuously exceeds 3 times Vh for 1 s.

[0046] Preferably, the respiratory-synchronized extracorporeal diaphragm nerve electrical stimulator of the application further comprises:

[0047] A nasal negative pressure sensor is arranged at the patient's nasal catheter interface and connected with the signal conditioning circuit, for collecting the patient's nasal negative pressure signal; the control unit receives the conditioned patient's nasal negative pressure signal;

[0048] The envelope duration of the electrical stimulation pulse is dynamically matched with the inspiratory period of the ventilator, specifically including:

[0049] The control unit acquires the inspiratory duration T vent of the ventilator in real time through the communication interface;

[0050] The envelope duration is set to 90% to 100% of T vent , and does not exceed ±5% of the actual inspiratory duration of the ventilator;

[0051] If the ventilator inspiration cycle signal is lost, the control unit automatically switches to an inspiration duration calculation mode based on the patient nasal negative pressure signal, ensuring that the electrical stimulation envelope is synchronized with spontaneous breathing.

[0052] Preferably, the respiratory synchronized extracorporeal phrenic nerve electrical stimulator of the present application, when the ventilator inspiration cycle signal is lost, the control unit automatically switches to an inspiration duration calculation mode based on the patient nasal negative pressure signal, specifically comprises:

[0053] 1) Signal loss determination: if the ventilator communication interface does not update the inspiration duration parameter for 3 consecutive breath cycles, or the received data fails the check, it is determined that the signal is lost;

[0054] 2) Nasal signal extraction: based on the patient's nasal negative pressure signal collected by the nasal negative pressure sensor in real time, the inspiration start point and end point are detected by a dynamic threshold algorithm, and the spontaneous inspiration duration T self is calculated.

[0055] 3) Envelope duration adjustment: the envelope duration of the electrical stimulation pulse is set to 90% to 95% of T self , and the deviation from the sliding average value of the spontaneous inspiration duration of the last 3 times is not more than ±3%;

[0056] 4) Redundancy synchronization check: after switching to the nasal negative pressure signal mode, the synchronization of the electrical stimulation envelope and the nasal negative pressure signal is compared every 5 breath cycles, and if the deviation exceeds 5%, T self is recalibrated.

[0057] Advantages:

[0058] The present application significantly improves the synchronization accuracy of electrical stimulation and inspiration action by real-time detection of patient end inspiration flow rate signal and dynamic matching of respiratory cycle. Experiments show that the synchronization deviation can be controlled within 50ms, the diaphragm contraction efficiency is increased by more than 30%, and the patient discomfort is reduced.

[0059] The present application introduces a flow rate threshold and an expiration cycle prohibition triggering mechanism to avoid misstimulation during low flow rate or expiration phase, reducing the risk of diaphragm fatigue. Clinical data shows that the mis-triggering rate is reduced from 15% of traditional technology to less than 3%.

[0060] The bandpass filter and the biphasic pulse design of the present application effectively suppress baseline drift and high frequency noise, and the signal-to-noise ratio of the inspiration flow rate signal is improved to more than 20dB, and the threshold determination accuracy is more than 95%.

[0061] The multi-signal cooperative triggering mechanism (flow rate + air pressure) of the present application reduces the influence of single signal interference, and the mis-triggering rate is further reduced to 1.5%, especially suitable for non-invasive ventilation or high air leakage scenes.

[0062] The time window synchronization and dual-condition verification strategy of this invention eliminates transient noise interference, improves trigger specificity to 98%, and maintains high reliability even when the patient coughs or the tubing vibrates.

[0063] The adjustable gain and two-stage filtering design of this invention adapt to the amplitude and frequency characteristics of signals from different patients, and the signal conditioning adaptability covers more than 90% of clinical cases, reducing the debugging time by 50%.

[0064] The dynamic threshold calibration and slope analysis logic of this invention improves the trigger sensitivity during the low-speed inhalation phase, and the synchronization rate remains stable at over 90% even when the inhalation flow rate fluctuates by ±40%.

[0065] The present invention enables personalized treatment through a flow rate linkage mechanism that links current intensity and frequency, shortens the patient's diaphragm activation time by 20%, improves ventilation efficiency by 25%, and avoids overload risks through a safety monitoring circuit.

[0066] This invention uses dynamic envelope matching of respiratory cycles to avoid overlap between stimulation and expiration, reducing the incidence of diaphragmatic fatigue by 40%, and achieving a synchronization deviation of less than ±3% in pressure support mode.

[0067] The nasal cavity signal backup mode of this invention ensures that the synchronization rate is maintained at more than 85% when the ventilator signal is lost, and the redundancy verification mechanism controls the synchronization deviation after mode switching within a clinically acceptable range (±5%). Attached Figure Description

[0068] Figure 1 Schematic diagram of the flow rate-time curve of a ventilator;

[0069] Figure 2 Schematic diagram of flow rate sensor interface and operational amplifier circuit;

[0070] Figure 3 Schematic diagram of matching the duration of electrical stimulation pulse envelope with the inspiratory cycle of a ventilator;

[0071] Figure 4 : Schematic diagram of threshold-based electrical stimulation triggering mechanism;

[0072] Figure 5 : Schematic diagram of electrical stimulation cessation mechanism based on peak flow rate percentage;

[0073] Figure 6 : Electrical stimulation waveform of an external diaphragmatic pacemaker;

[0074] Figure 7 : Figure 6 A magnified view of a portion of the waveform;

[0075] Figure 8 : Figure 6 The duration of the electrical stimulation pulse envelope (t) cCorresponding relationship diagram with respiratory cycle (T);

[0076] Figure 9 : Schematic diagram of inspiratory synchronous extracorporeal diaphragm pacemaker circuit principle. DETAILED DESCRIPTION

[0077] The application will be further described in detail below with reference to the accompanying drawings so that those skilled in the art can implement it according to the description and the drawings.

[0078] Figure 1 : Ventilator flow rate-time curve schematic diagram. The horizontal axis is time, and the vertical axis is flow rate. When the flow rate is greater than 0, it represents the inspiration cycle, and when the flow rate is less than 0, it represents the expiration cycle. The diagram is used to visually distinguish the inspiration and expiration stages of the ventilator, providing a time reference for subsequent synchronous electrical stimulation.

[0079] Figure 2 : Schematic diagram of flow rate sensor interface and operational amplifier circuit. It shows the access mode of the flow rate sensor at the patient end of the ventilator pipeline, as well as the design of the signal conditioning and filtering circuit, ensuring that the inspiration flow rate signal can be accurately detected and transmitted to the CPU for real-time analysis.

[0080] Figure 3 : Schematic diagram of matching between electrical stimulation pulse envelope duration and ventilator inspiration cycle. It explains that the duration of the electrical stimulation pulse should be less than the inspiration duration set by the ventilator (preset mode), or the envelope duration is automatically adjusted to dynamically adapt to the inspiration cycle (adaptive mode), to avoid excessive stimulation time leading to asynchrony between man and machine.

[0081] Figure 4 : Schematic diagram of threshold-based electrical stimulation triggering mechanism. When the inspiration flow rate reaches a set threshold (such as 5 L / min), electrical stimulation is started, and when the flow rate is lower than the threshold, stimulation is stopped. This mode ensures that stimulation is activated only during the effective inspiration phase, reducing the risk of ineffective stimulation.

[0082] Figure 5 : Schematic diagram of electrical stimulation stopping mechanism based on peak flow rate percentage. When the inspiration flow rate decreases from the peak value to a preset percentage (such as 20% of the peak flow rate), electrical stimulation is stopped. This mechanism combines dynamic flow rate changes to optimize the timing of stimulation termination, further ensuring the coordination between man and machine.

[0083] In combination Figures 6-9 , the patient using the ventilator has a common flow rate-time curve example of the ventilator as Figure 1 . When the flow rate is greater than 0, it is the inspiration cycle, and when the flow rate is less than 0, it is the expiration cycle. Figure 6 , t c is the envelope duration of the electrical stimulation pulse, and τ j is the interval between adjacent positive and negative pulses; Figure 7 , τ is the pulse width, and τ jTc is the envelope duration of the electrical stimulation pulse, T is the respiratory cycle. Figure 8 Tc is the envelope duration of the electrical stimulation pulse, T is the respiratory cycle.

[0084] A flow sensor is connected to the end of the breathing machine tube close to the patient to detect the inspiratory flow rate. Figure 2 A flow sensor interface and operational amplifier circuit are provided.

[0085] The signal of the flow sensor is connected to the analog-to-digital (AD) conversion port of the CPU after being conditioned and filtered by the operational amplifier. The CPU detects the inspiratory flow rate in real time.

[0086] When the inspiratory flow rate reaches a certain set threshold Vh, such as 5 L / min, the phrenic nerve electrical stimulation is started. The parameter settings of the electrical stimulation need to be matched with certain set parameters of the breathing machine, such as the envelope duration of the electrical stimulation pulse needs to be less than the inspiratory duration set by the breathing machine (see Figure 3 ), or the envelope duration of the electrical stimulation pulse can be automatically matched with the inspiratory cycle of the breathing machine.

[0087] There are multiple ways to automatically match, one, the electrical stimulation is only performed when the inspiratory flow rate is greater than or equal to a certain set threshold Vh, and the electrical stimulation is not performed when the inspiratory flow rate is less than this threshold (see Figure 4 ). Two, the electrical stimulation is performed when the inspiratory flow rate is greater than or equal to a certain set threshold Vh, and the electrical stimulation is stopped when the inspiratory flow rate is less than a certain percentage, such as 20%, of the peak flow rate Vpeak (see Figure 5 ).

[0088] The phrenic nerve electrical stimulation is only performed during the inspiratory cycle, and the phrenic nerve electrical stimulation is not performed during the expiratory cycle. This is to prevent the asynchronization between the human and the machine.

[0089] The flow sensor needs to be connected to the end of the breathing machine tube close to the patient to be able to sensitively sense the changes in the inspiratory flow rate.

[0090] According to one embodiment of the present application, the flow sensor can be connected to the end of the breathing machine tube close to the patient, and the installation position is less than 10 cm from the patient end interface. The sensor can be selected from the market's thermal or differential pressure flow sensor, and the material can be selected from polycarbonate or medical grade stainless steel. The sensor is connected to the breathing machine tube through a tee joint, and the tee joint can be selected from a standard Luer lock joint. During operation, the flow sensor detects the inspiratory flow rate signal in real time, the signal range covers 0 to 100 L / min, and the detection accuracy is ±1%. The output end of the sensor is connected to the signal conditioning circuit through a shielded cable, and the outer layer of the cable can be wrapped with polyurethane insulation material to reduce interference. When assembling, the sensor and the tube need to be axially aligned to avoid the influence of airflow turbulence on the detection accuracy.

[0091] The signal conditioning circuit can include an operational amplifier and a filter module. The operational amplifier can be a general-purpose instrument amplifier with a gain adjustable range of 10 to 100 times and a supply voltage of ±5V to ±15V. The filter module can be designed as a band-pass filter with a cutoff frequency range of 0.1Hz to 10Hz, a first-order high-pass filter for eliminating baseline drift, and a second-order low-pass filter for filtering out high-frequency noise. The circuit board material can be FR-4 substrate, and the connector can be gold-plated pins to reduce contact resistance. During operation, the inspiratory flow rate signal is amplified by the amplifier and then passes through the high-pass and low-pass filters in sequence, and finally output to the analog-to-digital conversion interface of the control unit. The signal conditioning circuit is assembled in the main control box of the electrical stimulator and connected to the sensor and control unit through a flat cable.

[0092] The control unit can be configured as an embedded microcontroller, and the sampling frequency of the analog-to-digital conversion interface can be set to 200Hz to 1kHz with a resolution of ≥12 bits. The preset inspiratory flow rate threshold Vh can be fixed at 5L / min, and the trigger condition requires that the signal mean value is ≥5L / min and the rising slope is ≥2L / min² in the continuous 3 sampling periods. The electrical stimulation module can use a biphasic pulse generator with an output pulse width of 0.1ms to 1ms, a frequency of 10Hz to 50Hz, and a current intensity of 5mA to 30mA. The module has a built-in safety monitoring circuit that cuts off the output when the flow rate exceeds 15L / min for 1s.

[0093] The control unit and the electrical stimulation module are connected through a flat cable on the PCB board, and the assembly position should be away from the high-voltage power supply to reduce electromagnetic interference. During operation, the control unit analyzes the flow rate signal in real time, triggers a pulse when the threshold is reached, and the pulse envelope length automatically matches the inspiratory period of the ventilator or the patient's spontaneous breathing signal.

[0094] Technical effects: Through the high-precision detection of the flow rate sensor, the noise suppression of the signal conditioning circuit, and the dynamic triggering mechanism of the control unit, the electrical stimulation pulse can be precisely synchronized with the breathing cycle. The stability of the signal processing link reduces the risk of false triggering, and the safety monitoring circuit ensures the safety of the patient. The system adapts to different ventilator parameters and is suitable for various clinical scenarios, improving the reliability and adaptability of extracorporeal diaphragmatic nerve electrical stimulation.

[0095] According to another embodiment of the application, the flow rate sensor can be connected to the ventilator circuit through a three-way interface, which can be selected from a standard Luer lock interface or an ISO 22mm medical interface, and the material can be selected from medical-grade polycarbonate or silicone. The sensor installation position needs to be less than 10 cm away from the patient end interface, which can be set to 5 cm, 8 cm or 10 cm. The sensor can be selected from a differential pressure or thermal flowmeter, with a range of 0 to 100 L / min and a detection accuracy of ±1.5%. The sensor housing can be made of ABS plastic or 304 stainless steel, and the internal sensor element can be encapsulated in epoxy resin to isolate moisture. When assembling, the sensor needs to be coaxially aligned with the circuit to avoid flow rate measurement errors caused by angle deviation. During operation, the sensor collects the inspiratory flow rate signal in real time, which is transmitted to the signal conditioning circuit through a shielded cable. The outer layer of the cable can be wrapped with an aluminum foil shield to reduce electromagnetic interference.

[0096] The control unit can be configured to stop the electrical stimulation when the inspiratory flow rate is less than 20% of the peak flow rate Vpeak. The real-time calculation of the peak flow rate Vpeak can be achieved by the sliding window method, and the window length can be set to 1s, 2s or 3s. The control unit can be selected from an embedded microcontroller, and the resolution of the analog-to-digital conversion interface can be set to 12 bits or 14 bits. The stop threshold of 20% of Vpeak can be fixed at a specific value, for example, if Vpeak is 25 L / min, the stop threshold is 5 L / min. The control unit is assembled in the main control box of the electrical stimulator and connected to the signal conditioning circuit through a flat cable. During operation, the control unit continuously monitors the inspiratory flow rate signal, and when the flow rate drops below 20% of the peak value, it immediately sends a stop command to the electrical stimulation module to cut off the pulse output. The parameters can be input through the configuration interface of the control unit, supporting manual calibration or adaptive algorithm dynamic adjustment.

[0097] The electrical stimulation pulse is triggered only during the inspiratory period, and is prohibited during the expiratory period. The trigger logic can be based on the inspiratory phase signal provided by the ventilator or by the flow rate signal to determine the inspiratory start and end points in real time. The electrical stimulation module can be selected from a bipolar pulse generator, with an output pulse width of 0.2ms, 0.5ms or 1ms, and a frequency range of 10Hz to 50Hz. The module can be integrated with an optical coupling isolation circuit to ensure electrical isolation between high-voltage output and low-voltage control signal. When assembling, the electrical stimulation module needs to be away from interference sources such as power transformers, and is fixed in a separate isolation compartment of the main control box. During operation, the control unit detects valid trigger conditions during the inspiratory period and outputs pulse signals to the phrenic nerve electrodes; when the expiratory period starts, the output channel is immediately closed, and the current working mode is displayed through the status indicator light.

[0098] Technical effects: By precise flow sensor installation positioning, peak flow dynamic threshold judgment, and inspiration cycle synchronous triggering mechanism, it can effectively avoid the mis-triggering of electrical stimulation in the expiration cycle, reduce patient discomfort. Real-time monitoring and rapid response of the control unit ensure the strict synchronization of electrical stimulation pulses and respiratory cycles, improving treatment safety. The modular design adapts to various respirator interfaces, enhancing the clinical applicability of the system, while the isolation circuit and shielding measures reduce the influence of external interference on signal acquisition.

[0099] According to another embodiment of the application, the filter module of the signal conditioning circuit can be designed as a band-pass filter, and the cutoff frequency range can be set to 0.1Hz to 10Hz, and specifically, 0.5Hz to 5Hz or 1Hz to 8Hz can be selected. The first-order cutoff frequency of the high-pass filter can be set to 0.1Hz, 0.5Hz or 1Hz to eliminate baseline drift; the second-order cutoff frequency of the low-pass filter can be set to 10Hz, 8Hz or 5Hz to filter out high-frequency noise. The filter circuit can use a ready-made integrated active filter chip, and the package form can be SOP or DIP, and the material can be silicon-based semiconductor. The circuit board substrate can be FR-4, and the connecting wire can be tin-plated copper wire to reduce signal attenuation. The band-pass filter is assembled on the signal conditioning circuit board and connected with the operational amplifier through the circuit board trace. During operation, the inspiratory flow rate signal is amplified and then passes through the high-pass and low-pass filters to eliminate low-frequency drift and high-frequency interference, and outputs a smooth flow rate signal to the control unit.

[0100] The pulse waveform output by the electrical stimulation module can include positive and negative biphasic pulses, the pulse width can be set to 0.1ms, 0.5ms or 1ms, the frequency can be set to 10Hz, 30Hz or 50Hz, and the current intensity can be set to 5mA, 15mA or 30mA. The pulse generator can use a ready-made biphasic constant current stimulation chip, and the output channel can be configured with an optocoupler isolation protection circuit. The shell of the electrical stimulation module can be made of aluminum alloy or ABS plastic, and the internal circuit board can be coated with a three-proof paint to enhance moisture resistance. The module is assembled in a separate isolated compartment of the main control box and connected with the control unit through a pinout, away from the power module to reduce interference. During operation, the control unit sends instructions according to the triggering conditions, the electrical stimulation module outputs pulses with the set parameters, and acts on the phrenic nerve through the electrode patch. The pulse parameters can be adjusted through the configuration interface of the control unit, supporting preset mode or custom input.

[0101] Technical effects: By band-pass filter to the effective filtering of inspiratory flow rate signal, can significantly improve the signal quality, reduce the risk of misjudgment caused by noise. The diversification of the parameters of the electric stimulation module adapts to the physiological needs of different patients, and the biphasic pulse design reduces the risk of tissue polarization damage. The modular structure and isolation measures ensure the stable operation of the system, and the flexible parameter adjustment function enhances the clinical applicability, providing reliable technical support for extracorporeal phrenic nerve electrical stimulation.

[0102] According to another embodiment of the application, the air pressure sensor can be connected to the airway interface of the ventilator pipeline. The control unit can be configured to analyze the flow rate signal and the air pressure signal synchronously, the flow rate preset threshold Q can be set to 3L / min, 5L / min or 8L / min, and the air pressure trigger condition can include that the air pressure signal is lower than the threshold Ph (for example, -2Pa to -5Pa) and the waveform slope is greater than or equal to S (0.2Pa / ms to 0.5Pa / ms). During operation, the control unit collects the flow rate and air pressure signals in real time, and outputs an electric stimulation pulse trigger instruction when the flow rate exceeds Q and the air pressure meets the trigger condition at the same time.

[0103] The trigger condition requires that the flow rate signal exceeds Q and the air pressure signal meets the threshold Ph and the slope S at the same time. The time window T can be set to 50ms, 100ms or 200ms, and if only a single signal meets the standard within the window, it is determined as invalid trigger. The electric stimulation module can use a biphasic pulse generator, and the output pulse width can be set to 0.2ms, 0.5ms or 1ms, and the current intensity can be set to 5mA to 30mA. The module can be integrated with an optical coupling isolation circuit, and the shell can be made of aluminum alloy or flame-retardant PC material. The electric stimulation module is assembled in a separate isolation compartment of the main control box and connected to the control unit through a pin array. During operation, the control unit detects the double signal condition within the time window T, and triggers a pulse if both conditions are met; if the window times out or only one condition is not met, the output is shielded and an invalid trigger is indicated by a status indicator light.

[0104] The air pressure sensor can be a piezoresistive or capacitive sensor with a range of -10kPa to +10kPa and a detection accuracy of ±0.5%. The material can be a medical-grade polycarbonate shell and a silicone seal ring, and the internal sensing element can be encapsulated in epoxy resin. The sensor is assembled near the airway interface of the ventilator pipeline, less than 15cm from the patient end interface, and connected to the pipeline through a three-way interface. The signal output end can be a shielded cable wrapped with a polyurethane insulation layer, connected to the analog-digital conversion interface of the control unit. During operation, the sensor detects the air pressure changes in the breathing pipeline in real time and outputs an analog signal to the control unit. The air pressure signal detection range can cover -5Pa to +5Pa, and the sampling frequency is set to 100Hz to 500Hz to ensure dynamic response capability. When assembling, the sensor and the pipeline should be coaxially aligned to avoid turbulent airflow interference with signal accuracy.

[0105] The flow rate sensor is connected to the breathing machine pipeline close to the patient end, and the flow rate threshold Q can be set to 3 L / min, 5 L / min or 8 L / min. The flow rate signal is input into the control unit after being processed by the signal conditioning circuit, which can include an operational amplifier and a filter module. The cutoff frequency range of the filter module is set to 0.1 Hz to 10 Hz. The air pressure trigger condition includes an air pressure signal lower than the threshold Ph, which can be set to -2 Pa, -3 Pa or -5 Pa. The control unit is configured to simultaneously receive signals from the flow rate sensor and the air pressure sensor. When the flow rate signal exceeds Q and the air pressure signal is lower than Ph, the electrical stimulation module is triggered to output a pulse. The electrical stimulation module can be a biphasic constant current pulse generator with an output current intensity of 5 mA to 30 mA and a pulse width of 0.1 ms to 1 ms.

[0106] The control unit can be an embedded microcontroller. The analog-to-digital conversion interface resolution of the control unit can be set to 12 bits or 16 bits, and the input voltage range covers -5 V to +5 V. During operation, the control unit analyzes the flow rate signal and the air pressure signal in real time. If the flow rate signal exceeds Q and the air pressure signal is lower than Ph, the electrical stimulation module is immediately triggered to output a pulse. Parameter settings can be input through the configuration interface of the control unit, supporting manual calibration or adaptive algorithm adjustment. When assembling, it is necessary to ensure that the signal lines of the flow rate sensor and the air pressure sensor are independently shielded to avoid cross interference.

[0107] Technical effects: By synchronously analyzing the dual trigger conditions of the inspiratory flow rate signal and the air pressure signal, the risk of false triggering caused by single signal interference is reduced, and the triggering accuracy of the electrical stimulation pulse is improved. The introduction of the air pressure sensor enhances the real-time monitoring capability of the pressure change in the breathing pipeline, ensuring the synchronization of the electrical stimulation pulse and the actual inspiratory action of the patient. The modular design and high-precision sensor selection improve the stability and adaptability of the system.

[0108] According to another embodiment of the application, the control unit can be configured to start a time window T upon detecting that the flow rate signal exceeds a threshold value Q, the window length can be set to 50 ms, 100 ms or 200 ms. The threshold value Q can be set to 3 L / min, 5 L / min or 8 L / min, the air pressure signal threshold value Ph can be set to -2 Pa, -3 Pa or -5 Pa, and the waveform slope S can be set to 0.2 Pa / ms, 0.3 Pa / ms or 0.5 Pa / ms. The control unit can be selected as an embedded microcontroller, the resolution of the analog-to-digital conversion interface of which can be set to 12 bits or 16 bits, and the input voltage range covers -5 V to +5 V. The air pressure sensor can be selected as a piezoresistive or capacitive sensor, the range of which covers -10 kPa to +10 kPa, and it is arranged near the airway interface of the ventilator pipeline and connected with the control unit through a flexible circuit board. During operation, when the flow rate signal exceeds Q, the control unit immediately starts the time window T, and synchronously detects whether the air pressure signal is lower than Ph and the slope is ≥ S within the window, and triggers the electrical stimulation if both conditions are met.

[0109] Within the time window T, if only the flow rate or air pressure signal meets the standard, it is determined as invalid trigger and the output is shielded. The determination logic of the control unit can be realized through a state machine or a threshold comparison algorithm, and the algorithm can be written based on C language. The determination result of invalid trigger can be prompted through a status indicator light or a buzzer, and the indicator light can be selected as an LED module, and the color can be defined as red to represent invalid trigger. The electrical stimulation module can be selected as a biphasic constant current pulse generator, and the output pulse width can be set to 0.2 ms, 0.5 ms or 1 ms, and the current intensity can be set to 5 mA to 30 mA. The module shell can be selected as an aluminum alloy or a flame-retardant PC material, and the internal circuit board can be coated with a three-proof paint to enhance environmental resistance. The electrical stimulation module is arranged in a separate isolated bin of the main control box and connected with the control unit through a pinout, away from the high-frequency interference source. During operation, the control unit compares the flow rate and air pressure signals in real time within the time window T, and immediately closes the output channel and records the number of invalid triggers if the double conditions are not met at the same time.

[0110] If the ventilator communication interface fails to update parameters or data for 3 consecutive breathing cycles, the control unit can switch to a nasal negative pressure signal autonomous calculation mode. The nasal negative pressure signal can be collected by a nasal negative pressure sensor, and a dynamic threshold algorithm can be realized based on a moving average method or a peak detection method. The autonomous inspiration duration T selfThe calculation can be based on the sliding average of the length of 3 consecutive inhalations, and the deviation allowed range is ±3%. The control unit can be configured with a redundancy check module, and the synchronization of the electrical stimulation envelope and the nasal negative pressure signal is compared every 5 breathing cycles, and if the deviation exceeds 5%, it is recalibrated. The nasal negative pressure sensor can be a micro piezoelectric sensor, which is installed at the patient's nasal interface and connected to the main control box through a flexible lead. During operation, the control unit automatically switches to the nasal signal mode after signal loss, recalculates the inhalation period and adjusts the length of the electrical stimulation envelope to ensure synchronization with the patient's spontaneous breathing.

[0111] Technical effects: Through the time window mechanism and the combined judgment of the double signals, the risk of false triggering caused by single signal interference is significantly reduced, and the accuracy of the electrical stimulation pulse is improved. The redundancy calibration and autonomous mode switching function enhances the fault tolerance of the system when the ventilator signal is lost, ensuring treatment continuity. The modular design and isolation measures reduce external interference, and the state indication and invalid trigger recording function facilitate clinical operation and monitoring, providing a highly reliable solution for extracorporeal phrenic nerve electrical stimulation.

[0112] According to another embodiment of the application, the operational amplifier can be a general-purpose instrument amplifier, the gain adjustable range can be set to 10 times, 50 times or 100 times, and the supply voltage can be selected from ±5V, ±12V or ±15V. The packaging form of the amplifier can be SOIC or DIP, and the material can be silicon-based semiconductor. The circuit board substrate can be FR-4, and the connector can be gold-plated pins to reduce contact resistance. The operational amplifier is assembled on the signal conditioning circuit board and connected to the output end of the flow rate sensor through a shielded cable. During operation, the inhalation flow rate signal is amplified by the amplifier and output to the filtering module. The gain parameter can be adjusted by a potentiometer or a digital control interface, supporting manual calibration or automatic adaptation to different signal strengths.

[0113] The filtering module can be designed as a two-stage filtering structure. The cutoff frequency of the first-stage high-pass filter can be set to 0.1Hz, 0.5Hz or 1Hz to eliminate baseline drift, and the cutoff frequency of the second-stage low-pass filter can be set to 20Hz, 50Hz or 100Hz to filter out high-frequency noise. The filter can be a ready-made integrated active filter chip, the packaging form can be SOP or QFN, and the material can be silicon-based semiconductor. The circuit board traces can be designed as differential signal paths to reduce crosstalk. The filtering module is assembled on the signal conditioning circuit board next to the operational amplifier and connected through copper foil traces. During operation, the amplified signal passes through the high-pass and low-pass filters in sequence, and the interference components are filtered out and output to the analog-to-digital conversion interface of the control unit.

[0114] The output end of the signal conditioning circuit can be connected to an analog-digital conversion interface of the control unit, the sampling frequency of the analog-digital conversion interface can be set to 200 Hz, 500 Hz or 1 kHz, the resolution can be set to 12 bits, 14 bits or 16 bits, and the input voltage range covers -5 V to +5 V. The control unit can be selected as an embedded microcontroller, the circuit board material can be selected as FR-4, and the connecting wire can be selected as a multi-core shielding wire. The signal conditioning circuit is assembled in the main control box of the electrical stimulator, connected to the control unit through a flat cable, and the length of the flat cable is not more than 15 cm to reduce signal attenuation. During operation, the filtered flow rate signal is digitized through the analog-digital conversion interface and transmitted to the core algorithm module of the control unit for real-time analysis, triggering or stopping the electrical stimulation pulse.

[0115] Technical effects: Through the adjustable gain of the operational amplifier and the multi-stage filter design, the signal-to-noise ratio of the inspiratory flow rate signal can be effectively improved, and high-precision data can be obtained by the control unit. The structure optimization of the signal conditioning circuit reduces the interference risk in the signal transmission process, and adapts to different breathing machine working environments. The high resolution and wide input range of the analog-digital conversion interface enhance the compatibility of the system, and provide a stable and reliable data processing foundation for extracorporeal diaphragmatic nerve electrical stimulation.

[0116] According to another embodiment of the application, the sampling frequency of the analog-digital conversion interface can be set to 200 Hz, 500 Hz or 1 kHz, the resolution can be set to 12 bits, 14 bits or 16 bits, and the input voltage range can cover -5 V to +5 V. The interface can be selected as a general-purpose analog-digital conversion chip on the market, the packaging form can be selected as QFP or SOP, and the material can be selected as silicon-based semiconductor. The analog-digital conversion interface is assembled on the circuit board of the control unit and connected to the central processing unit of the control unit through the SPI or I2C bus. During operation, the conditioned inspiratory flow rate signal is transmitted to the analog-digital conversion interface through the output end of the signal conditioning circuit, the interface converts the analog signal into a digital signal at the set frequency, and transmits it to the core algorithm module of the control unit. The parameter configuration can be adjusted through the software interface of the control unit, supporting preset mode or manual input.

[0117] The preset inhalation flow rate threshold Vh is fixed at 5 L / min, the number of continuous sampling periods can be set to 3, 4 or 5, and the rising slope threshold can be set to 2 L / min2, 3 L / min2 or 4 L / min2. The control unit can be an embedded microcontroller, and its algorithm can be written in C language or Python. The real-time detection logic is implemented through a state machine. The control unit is assembled in the main control box of the electrical stimulator and is connected to the signal conditioning circuit through a wire harness. During operation, the control unit calculates the average value of the flow rate signal in the last 3 sampling periods. If the average value is ≥ 5 L / min and the rising slope is ≥ 2 L / min2, it is determined to be an effective inhalation trigger. The trigger signal is transmitted to the electrical stimulation module through a digital output pin, and the pulse output is started.

[0118] When the inhalation flow rate signal fluctuates more than 50% of Vh (i.e. 2.5 L / min) within 1s, the control unit automatically starts dynamic threshold calibration. The calibration range can be set to 30%, 50% or 70% of the current flow rate peak value. For example, if the peak flow rate is 10 L / min, Vh is adjusted to 3 L / min to 7 L / min. The calibration algorithm can be implemented based on the sliding window method or the peak detection method. The memory of the control unit can store historical flow rate data to support dynamic adjustment. The calibrated threshold takes effect immediately and is synchronized to the electrical stimulation module through the output interface of the control unit. During operation, if abnormal flow rate fluctuations are detected, the control unit updates the threshold parameters in real time to ensure the adaptability of the trigger conditions.

[0119] Technical effects: Through the high-precision analog-digital conversion interface and real-time detection logic, the effective inhalation trigger signal can be accurately identified, and the false judgment caused by signal noise can be reduced. The dynamic threshold calibration mechanism enhances the adaptability of the system to changes in the patient's breathing pattern and improves the synchronization of the electrical stimulation pulse with the breathing cycle. The flexible configuration of parameters and automatic calibration function simplify the clinical operation and ensure the safety and reliability of extracorporeal diaphragmatic nerve electrical stimulation.

[0120] According to another embodiment of the present application, the electrical stimulation module can be configured to dynamically adjust the current intensity according to the difference between the real-time inspiratory flow rate and the threshold value Vh, and the current intensity can be increased by 0.5 mA, 1 mA or 2 mA for each 1 L / min increase in the difference. The initial current intensity can be set to 5 mA, 8 mA or 10 mA, and the maximum current intensity is limited to 30 mA. The control unit can be selected from an embedded microcontroller, and the built-in algorithm can achieve dynamic adjustment based on linear interpolation or piecewise function. The electrical stimulation module can be selected from a dual-phase constant-current pulse generator, the shell can be selected from aluminum alloy or flame-retardant PC material, and the internal circuit board can be coated with three-proof paint. The module is assembled in a separate isolated bin of the main control box and connected to the control unit through a pin array. During operation, the control unit calculates the flow rate difference in real time, and if the current flow rate is 7 L / min (Vh = 5 L / min), the difference of 2 L / min corresponds to an increase of 1 mA to 2 mA in the current intensity, and the final output current is the initial value plus the increment, but not more than 30 mA.

[0121] The electrical stimulation pulse frequency can be adjusted in stages according to the real-time inspiratory flow rate, and when the flow rate reaches or exceeds 2 times Vh (i.e. 10 L / min), the frequency can be increased to 50 Hz; when the flow rate is less than Vh, the frequency can be reduced to 10 Hz or 15 Hz. The safety monitoring circuit can be integrated into the electrical stimulation module, and when the real-time flow rate exceeds 3 times Vh (i.e. 15 L / min) for 1 s, the output is immediately cut off and an audible and visual alarm is triggered. The alarm module can be selected from a combination of a piezoelectric buzzer and an LED indicator, the buzzer frequency can be set to 2 kHz to 4 kHz, and the indicator color can be defined as red. The safety circuit is assembled inside the module and isolated from the main control unit by an optocoupler. During operation, the control unit continuously monitors the flow rate, the frequency adjustment is controlled by a PWM signal, and the safety circuit independently detects abnormal flow rate and performs hard cut-off.

[0122] The envelope duration of the electrical stimulation pulse can be dynamically matched to the inspiratory duration T vent set by the ventilator vent , the envelope duration can be set to 90%, 95% or 100% of T vent , with an allowable deviation of not more than ±5%. The control unit can communicate with the ventilator through RS-232 or CAN bus to obtain T vent parameters in real time. The communication interface can be selected from a standard isolated transceiver and assembled at the edge of the control unit circuit board. During operation, if the ventilator communication signal is lost, the control unit automatically switches to an autonomous calculation mode based on the nasal negative pressure signal, and the envelope duration is adjusted to 90% to 95% of the sliding average of the duration of the last 3 autonomous inhalations. The nasal negative pressure sensor can be selected from a micro piezoelectric sensor and assembled at the patient's nasal catheter interface, connected to the main control box through a shielded wire.

[0123] Technical effects: Through the linkage adjustment of dynamic current intensity and frequency, the precise matching of electric stimulation intensity and patient's respiratory effort level can be realized, and the treatment pertinence is improved. The safety monitoring mechanism and hard cut-off function effectively prevent the risk of excessive stimulation and protect the safety of patients. The dynamic matching of envelope length and autonomous mode switching ensure the continuous and reliable operation of the system when the ventilator signal is abnormal, and enhance the adaptability and stability of clinical application.

[0124] According to another embodiment of the application, the control unit can be connected with the ventilator through an RS-232 or CAN bus communication interface to obtain the inspiratory time T vent set by the ventilator in real time. vent The envelope length can be set to 90%, 95% or 100% of T vent , with an allowable deviation of not more than ±5%. The communication interface can be selected as an isolation transceiver chip, which is assembled at the edge position of the control unit circuit board, and the material can be selected as FR-4 substrate and gold-plated pins. During operation, the control unit receives T vent parameters every breathing cycle, automatically calculates the envelope length and transmits it to the electric stimulation module. For example, if T self is 1s, the envelope length is 0.9s to 1s. The parameter loss judgment condition can be set as no updated data or verification failure for 3 consecutive breathing cycles.

[0125] When the ventilator signal is lost, the control unit switches to the nasal negative pressure signal mode. The nasal negative pressure sensor can be selected as a micro piezoelectric sensor with a range of -5kPa to +5kPa, which is assembled at the patient's nasal catheter interface and connected with the main control box through a flexible shielded wire. The dynamic threshold algorithm can be based on the sliding average method or the peak detection method to calculate the spontaneous inspiration time T self . For example, the sliding average of the inspiration time of 3 consecutive breaths is 1.2s, and the envelope length is adjusted to 1.08s to 1.14s (90% to 95%). During operation, the control unit collects the nasal negative pressure signal in real time, detects the start and end points of inspiration, dynamically updates the envelope length, and ensures synchronization with the patient's spontaneous breathing.

[0126] The control unit can be configured to compare the synchronization of the electric stimulation envelope and the nasal negative pressure signal every 5 breathing cycles, with a deviation threshold of 5%. If the deviation exceeds the threshold, recalibrate T selfAnd adjust the envelope length. The check result is prompted by the status indicator light, and the indicator light can be selected as a double-color LED. Green indicates normal synchronization, and yellow indicates that calibration is required.

[0127] Technical effect: By dynamically matching the inspiratory duration of the ventilator and the autonomous nasal signal calculation, the high synchronization of the electric stimulation envelope and the patient's respiratory cycle is ensured, and the treatment interruption caused by signal loss is reduced. The redundancy verification mechanism improves the robustness of the system in complex working conditions and ensures the stability of long-term use. The accurate detection and dynamic calibration function of the nasal negative pressure sensor enhance the adaptability of the system to individual differences of patients, providing safe and reliable electric stimulation treatment support for clinical use.

[0128] According to another embodiment of the application, the control unit can be configured to determine signal loss when the ventilator communication interface does not update the inspiratory duration parameter for 3 consecutive respiratory cycles, or when data verification fails. The verification failure condition can include CRC verification error or data frame timeout (for example, the timeout time is set to 500ms). The control unit can be selected as an embedded microcontroller, the communication interface can be selected as an isolated RS-485 or CAN bus module, and the communication interface can be assembled at the edge position of the control unit circuit board. The material can be selected as FR-4 substrate and gold-plated connector. During operation, the control unit monitors the ventilator communication state in real time, and if valid data is not received for 3 consecutive cycles, a mode switching instruction is triggered immediately, and an event log is recorded.

[0129] The nasal negative pressure sensor can be selected as a piezoresistive or piezoelectric microsensor with a range of -5kPa to +5kPa, and can be assembled at the patient's nasal catheter interface and connected to the main control box through a shielded wire. The dynamic threshold algorithm can be based on the sliding window method, and the window length can be set to 200ms or 300ms to detect the start and end points of inspiration. The autonomous inspiratory duration T self can be calculated as the sliding average of the inspiratory duration of the last 3 breaths, with an allowable deviation of ±3%. During operation, the control unit acquires the nasal negative pressure signal, filters out noise through a band-pass filter (cutoff frequency 0.1Hz to 10Hz), dynamically identifies the inspiration phase and calculates T self . For example, if the inspiratory duration of the last 3 breaths is 1.1s, 1.2s and 1.0s, then T self is 1.1s.

[0130] The electric stimulation envelope duration can be set to 90% to 95% of T self , for example, when T self is 1.1s, the envelope duration is 0.99s to 1.05s. The redundancy verification can be performed every 5 breaths, and the synchronization deviation threshold is set to 5%. The verification logic can be based on timestamp comparison. If the deviation between the envelope trigger time and the start point of the nasal signal inspiration exceeds 5%, T selfThe calibration data can be stored in the EEPROM of the control unit. During operation, the control unit calculates the time difference in the redundancy check period, and if it exceeds the limit, it triggers the calibration process, updates the moving average and adjusts the envelope length. The check result is indicated by a dual-color LED indicator, green for normal synchronization and yellow for calibration.

[0131] Technical effects: Through the rapid determination of ventilator signal loss and autonomous mode switching, the electrical stimulation treatment is ensured to continue running when the device communication is abnormal, reducing the risk of treatment interruption. The dynamic extraction of nasal negative pressure signal and the redundancy check mechanism improve the adaptability of the system to the patient's autonomous breathing mode, ensuring the precise synchronization of the stimulation pulse. The modular design and real-time calibration function enhance the reliability of clinical operation, providing a high-robustness solution for extracorporeal phrenic nerve electrical stimulation.

[0132] Although the embodiments of the present application have been disclosed as above, they are not limited only to the applications listed in the specification and embodiments, and can be fully applied to various fields suitable for the present application, and additional modifications can be easily made by those skilled in the art, and therefore the present application is not limited to specific details and the figures shown and described herein, without departing from the general concept defined by the claims and the equivalent scope.

Claims

1. An external phrenic nerve electrical stimulator for synchronized breathing, characterized in that, include: A flow rate sensor is connected to the ventilator tubing near the patient to detect inspiratory flow rate signals in real time. A signal conditioning circuit, connected to the flow rate sensor, includes an operational amplifier and a filter module, used to amplify and filter the intake flow rate signal; The control unit has an analog-to-digital conversion interface, receives the conditioned inhalation flow rate signal, and detects in real time whether the inhalation flow rate has reached the preset threshold Vh. An electrical stimulation module, connected to the control unit, outputs an electrical stimulation pulse to the phrenic nerve when the inspiratory flow rate reaches or exceeds Vh; the envelope duration of the electrical stimulation pulse is less than or equal to the inspiratory duration set by the ventilator, or automatically matches the inspiratory cycle of the ventilator. A pressure sensor, mounted near the airway interface of the ventilator tubing and connected to the control unit, is used to detect the pressure signal within the ventilator tubing in real time. The control unit is configured to synchronously analyze the inspiratory flow rate signal and the pressure signal. When the inspiratory flow rate signal exceeds a preset threshold Q and the pressure signal meets the triggering conditions, the electrical stimulation module is triggered to output a pulse. The control unit is also configured to analyze the inspiratory flow rate signal and the pressure signal through a time window synchronization mechanism, specifically including: When the inspiratory flow rate signal is detected to exceed the threshold Q, the start-up time window T is 50ms to 200ms; If, within window T, a pressure signal lower than the preset threshold Ph and a waveform slope greater than or equal to S (where S is between 0.2 Pa / ms and 0.5 Pa / ms) are detected simultaneously, an electrical stimulation pulse is triggered. If only a single signal within window T meets the criteria, it is considered an invalid trigger and the output is blocked.

2. The external phrenic nerve electrical stimulator for respiratory synchronization according to claim 1, characterized in that: The control unit stops electrical stimulation when the inspiratory flow rate is less than 20% of the peak flow rate Vpeak; The electrical stimulation pulse is triggered only during the inspiratory cycle and is prohibited from being output during the expiratory cycle. The flow sensor is connected to the ventilator tubing via a three-way connector, and the installation position is less than 10cm away from the patient end interface.

3. The external phrenic nerve electrical stimulator for respiratory synchronization according to claim 1, characterized in that: The filtering module of the signal conditioning circuit is a bandpass filter with a cutoff frequency range of 0.1Hz to 10Hz; The pulse waveform output by the electrical stimulation module includes positive and negative biphasic pulses, with a pulse width of 0.1ms to 1ms, a frequency of 10Hz to 50Hz, and a current intensity of 5mA to 30mA.

4. The external phrenic nerve electrical stimulator for respiratory synchronization according to claim 1, characterized in that: The operational amplifier is configured to amplify the intake air velocity signal, with an adjustable gain range of 10 to 100 times; The filtering module includes two levels of filtering: the first level is a high-pass filter with a cutoff frequency of 0.1Hz to 10Hz, used to eliminate baseline drift; the second level is a low-pass filter with a cutoff frequency of 20Hz to 100Hz, used to filter out high-frequency noise. The output of the signal conditioning circuit is connected to the ADC module of the control unit to transmit the processed intake airflow speed signal.

5. The external phrenic nerve electrical stimulator for respiratory synchronization according to claim 1, characterized in that: The control unit is configured to receive the conditioned inhalation flow rate signal through an analog-to-digital conversion interface and detect in real time whether the inhalation flow rate reaches the preset threshold of 5L / min; The analog-to-digital conversion interface has a sampling frequency of 200Hz to 1kHz, a resolution of ≥12 bits, and an input voltage range of -5V to +5V. The real-time detection logic includes: If the average value of the inspiratory flow rate signal is ≥ Vh and the rising slope is ≥ 2L / min² within three consecutive sampling periods, it is determined to be an effective inspiratory trigger. When the inhalation flow rate signal fluctuates by more than 50% of Vh within 1 second, dynamic threshold calibration is initiated to adjust Vh to 30% to 70% of the current peak flow rate.

6. The external phrenic nerve electrical stimulator for respiratory synchronization according to claim 1, characterized in that: The electrical stimulation module is configured to output dynamically adjustable electrical stimulation pulses linked to the real-time inspiratory flow rate to the phrenic nerve when the inspiratory flow rate reaches or exceeds Vh. The current intensity of the electrical stimulation pulse is dynamically adjusted according to the difference between the real-time inspiratory flow rate and the threshold Vh. For every 1 L / min increase in the difference, the current intensity increases by 0.5 mA to 2 mA. The initial current intensity is 5 mA to 10 mA, and the maximum current intensity does not exceed 30 mA. The frequency of the electrical stimulation pulses is adjusted in stages according to the real-time inspiratory flow rate. When the inspiratory flow rate reaches or exceeds twice Vh, the frequency is increased to 50Hz; when the inspiratory flow rate is lower than Vh, the frequency is reduced to 10Hz. The electrical stimulation module has a built-in independent safety monitoring circuit. When the real-time inhalation flow rate continuously exceeds 3 times Vh for 1 second, the output is immediately cut off and an audible and visual alarm is triggered.

7. The external phrenic nerve electrical stimulator for respiratory synchronization according to claim 1, characterized in that, Also includes: A nasal negative pressure sensor is mounted at the patient's nasal cannula interface and connected to a signal conditioning circuit to collect the patient's nasal negative pressure signal. The control unit receives the adjusted negative pressure signal from the patient's nasal cavity; The envelope duration of the electrical stimulation pulse is dynamically matched to the inspiratory cycle of the ventilator, specifically including: The control unit obtains the inspiratory duration T set by the ventilator in real time through the communication interface. vent ; The envelope duration is set to T. vent 90% to 100%, and not exceeding ±5% of the actual inspiratory time of the ventilator; If the ventilator inspiratory cycle signal is lost, the control unit automatically switches to the inspiratory duration calculation mode based on the negative pressure signal in the patient's nasal cavity to ensure that the electrical stimulation envelope is synchronized with spontaneous breathing.

8. The external phrenic nerve electrical stimulator for respiratory synchronization according to claim 7, characterized in that: When the ventilator inspiratory cycle signal is lost, the control unit automatically switches to an inspiratory duration calculation mode based on the patient's nasal negative pressure signal, specifically including: 1) Signal loss determination: If the ventilator communication interface fails to update the inspiratory duration parameter for three consecutive respiratory cycles, or if the received data verification fails, it is determined that the signal is lost. 2) Nasal cavity signal extraction: Based on the real-time acquisition of the patient's nasal cavity negative pressure signal by the nasal cavity negative pressure sensor, the inspiratory start point and end point are detected by a dynamic threshold algorithm, and the spontaneous inspiratory duration T is calculated. self ; 3) Envelope duration adjustment: Set the envelope duration of the electrical stimulation pulse to T. self 90% to 95%, and the deviation from the sliding average of the duration of three consecutive spontaneous inhalations does not exceed ±3%; 4) Redundancy synchronization check: After switching to the nasal negative pressure signal mode, the synchronization between the electrical stimulation envelope and the nasal negative pressure signal is compared every 5 respiratory cycles. If the deviation exceeds 5%, T is recalibrated. self .

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