Pulse Oscillation Respiratory Impedance Detection Method and Detection System

Abstract

The present invention provides a method for detecting respiratory impedance by pulse oscillation, comprising the following steps: generating an oscillating airflow at a fixed frequency, respectively collecting the respiratory pressure and respiratory flow data of a subject to obtain a pulse-respiration superimposed wave pressure curve and a pulse-respiration superimposed wave flow curve; S2. respectively performing spline curve fitting on the pulse-respiration superimposed wave pressure curve and the pulse-respiration superimposed wave flow curve to obtain an interference pressure curve and an interference flow curve; removing the interference pressure curve from the pulse-respiration superimposed wave pressure curve to obtain a pulse pressure curve; removing the interference flow curve from the pulse-respiration superimposed wave flow curve to obtain a pulse flow curve; determining the respiratory impedance according to the pulse pressure curve and the pulse flow curve. The present invention also provides a respiratory impedance detection system adopting the above method. The method and system of the present invention have a simple structure and high detection accuracy, and can truly reflect the health status of the subject.

Description

Technical Field

[0001] The present invention relates to the technical field of medical detection, and particularly relates to a method and a detection system for detecting respiratory impedance by impulse oscillation. Background Art

[0002] Lung function detection is one of the necessary examination methods for respiratory system diseases, mainly used to detect the patency of the respiratory tract, the size of lung volume, etc. It has important clinical value in aspects such as early detection of lung and airway lesions, assessment of the severity and prognosis of diseases, assessment of the tolerance to surgery or labor intensity.

[0003] Respiratory impedance includes airway resistance and the resistance generated by the chest and lung tissues, which can truly reflect the respiratory state of the subject and is a conventional and important detection method for lung function detection. By calculating the respiratory impedance of the subject, the lung health status of the subject can be understood. The prior art usually uses the occlusion method, esophageal manometry, body plethysmography or forced oscillation method to measure respiratory impedance. However, the occlusion method uses the oral pressure after occlusion to replace the alveolar pressure before occlusion, and is only suitable for measuring airway resistance; esophageal manometry can also be used to measure lung resistance, but usually other methods are needed to measure airway resistance; body plethysmography requires blocking the respiratory passage first and letting the subject continue to maintain the breathing action, and calculates the thoracic gas volume by measuring the changes in oral pressure and the pressure in the body plethysmograph box. This test method has complex steps and a narrow application range; while the forced oscillation method uses an external signal source, and an oscillator generates an external pressure signal to measure the flow rate change that occurs in the respiratory system of the subject under this pressure, so as to obtain respiratory impedance data. However, during the test process, the oscillation wave generated by the oscillator will be superimposed on the respiratory wave of the subject, and the respiratory wave will interfere with the measurement of respiratory impedance, resulting in low reliability of the respiratory impedance detection result. Summary of the Invention

[0004] Based on this, the present invention provides a method for detecting respiratory impedance. By generating an oscillation wave through impulse oscillation and then separating the respiratory wave from the superimposed wave of the oscillation wave and the respiratory wave, the accuracy of respiratory impedance detection is improved.

[0005] An object of the present invention is to provide a method for detecting respiratory impedance by impulse oscillation, including the following steps:

[0006] S1. Generate an oscillating airflow at a fixed frequency f, respectively collect the subject's respiratory pressure and respiratory flow data, and obtain the pulse-respiration superimposed wave pressure curve and the pulse-respiration superimposed wave flow curve of the subject; the abscissa of the pulse-respiration superimposed wave pressure curve and the pulse-respiration superimposed wave flow curve is the sampling data length, and the ordinates are the collected respiratory pressure data and respiratory flow data respectively; the sampling data length is the product of the sampling duration and the sampling frequency, the sampling duration is 30 to 90 seconds, and the sampling frequency is 128 to 1000 Hz;

[0007] S2. Respectively perform spline curve fitting on the pulse-respiration superimposed wave pressure curve and the pulse-respiration superimposed wave flow curve to obtain an interference pressure curve and an interference flow curve;

[0008] S3. Remove the interference pressure curve from the pulse-respiration superimposed wave pressure curve to obtain a pulse pressure curve; remove the interference flow curve from the pulse-respiration superimposed wave flow curve to obtain a pulse flow curve;

[0009] S4. Determine the respiratory impedance according to the pulse pressure curve and the pulse flow curve.

[0010] Further, the step S2 is: segment the pulse-respiration superimposed wave pressure curve and the pulse-respiration superimposed wave flow curve according to each pulse signal of the oscillating airflow, and respectively perform spline curve fitting on each segment of the pulse-respiration superimposed wave pressure curve and the pulse-respiration superimposed wave flow curve.

[0011] Further, the method of fitting according to the pulse time period of the oscillating airflow is: the starting time point of the positive signal of the pulse oscillation voltage signal corresponds to the starting time point of the positive pulse of the pulse-respiration superimposed wave, and the ending time point of the positive signal of the pulse oscillation voltage signal corresponds to the ending time point of the positive pulse of the pulse-respiration superimposed wave; the starting time point of the negative signal of the pulse oscillation voltage signal corresponds to the starting time point of the negative pulse of the pulse-respiration superimposed wave, and the ending time point of the negative signal of the pulse oscillation voltage signal corresponds to the ending time point of the negative pulse of the pulse-respiration superimposed wave.

[0012] Further, during the spline curve fitting of the pulse wave, the fitting direction of the spline curve is guided by the midpoint of the time interval between the previous pulse and the current pulse and the time interval between the next pulse and the current pulse.

[0013] Further, determine the pulse respiratory resistance-frequency curve and the pulse respiratory reactance-frequency curve according to the pulse pressure curve and the pulse flow curve, and determine the respiratory impedance from the pulse respiratory resistance-frequency curve and the pulse respiratory reactance-frequency curve.

[0014] The second object of the present invention is to provide a pulse oscillation respiratory impedance detection system for detecting the respiratory impedance of a subject, where the respiratory impedance includes respiratory resistance and respiratory reactance. The system includes an oscillator, a pressure sensor, a flow sensor, a processor, and a storage unit. The oscillator is used to generate an oscillating air flow with a fixed frequency f to the airway of the subject, where f is 1 to 3 Hz; the pressure sensor is used to detect the respiratory pressure of the subject's airway; the flow sensor is used to detect the respiratory flow of the subject's airway; the processor is connected to the pressure sensor and the flow sensor and receives the respiratory pressure and respiratory flow signals; the storage unit stores multiple instructions, and when the instructions are executed by the processor, the processor executes the respiratory impedance detection method described in any one of the above.

[0015] Further, the respiratory detection system includes a respiratory circuit that connects the subject's mouth and the atmospheric environment, and the flow sensor and the pressure sensor are arranged in the respiratory circuit; the oscillator is an external speaker for generating an oscillating air flow to the subject.

[0016] The respiratory impedance detection method provided by the present invention can remove the interference caused by the subject's own respiratory wave during the detection process, and the detection result is more accurate, and can truly reflect the thoracic and pulmonary health status of the subject. Description of the Drawings

[0017] Figure 1 is a schematic structural diagram of the respiratory impedance detection system of the present invention.

[0018] Figure 2 is a schematic structural diagram of the respiratory impedance detection system of the first embodiment.

[0019] Figure 3 is the pulse-respiration superimposed wave pressure curve in the first embodiment.

[0020] Figure 4 is the pulse-respiration superimposed wave flow curve in the first embodiment.

[0021] Figure 5 is the interference pressure curve in the first embodiment.

[0022] Figure 6 is the interference flow curve in the first embodiment.

[0023] Figure 7 is the pulse pressure curve in the first embodiment.

[0024] Figure 8 is the pulse flow curve in the first embodiment.

[0025] Figure 9 is the pulse respiratory resistance-frequency curve in the first embodiment.

[0026] Figure 10 is the pulse respiration reactance - frequency curve in the first embodiment. Specific embodiments

[0027] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. The accompanying drawings show preferred embodiments of the present invention. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0029] Reference Figure 1 , the present invention provides a pulse oscillation respiration impedance detection system for detecting the respiration impedance of a subject, including respiratory resistance R and respiratory reactance X. The respiration impedance detection system includes an oscillator, a pressure sensor, a flow sensor, a processor, and a storage medium. The oscillator is used to generate an oscillating air flow with a fixed frequency f to the airway of the subject, and the fixed frequency f is 1 to 3 Hz; the pressure sensor is used to detect the respiratory pressure of the airway of the subject when affected by the oscillating air flow; the flow sensor is used to detect the respiratory flow of the airway of the subject when affected by the oscillating air flow; the processor is connected to the pressure sensor and the flow sensor and receives the respiratory pressure signal and respiratory flow signal collected by the pressure sensor and the flow sensor; the storage unit stores multiple instructions, and when the instructions are executed by the processor, the processor obtains the respiration impedance according to the collected respiratory pressure signal and respiratory flow signal.

[0030] Reference Figure 2 , in the first embodiment of the present invention, the respiration detection system includes a respiration circuit that communicates the mouth of the subject with the atmospheric environment, and the flow sensor and the pressure sensor are arranged in the respiration circuit; the oscillator is an external loudspeaker for generating an oscillating air flow to the subject.

[0031] Further, in this embodiment, a filter is further provided in the respiration circuit. The filter is arranged between the mouth of the subject and the atmospheric environment for filtering the exhaled gas exhaled from the mouth of the subject; the respiration circuit is connected to the mouth of the subject through a mouthpiece.

[0032] In this embodiment, the speaker is set to generate an oscillating air flow with a fixed frequency f of 2.5 Hz; the sampling duration is 60 s, and the sampling frequency is 500 Hz.

[0033] The specific method for obtaining the respiratory impedance according to the collected respiratory pressure signal, respiratory flow signal and respiratory flow signal includes the following steps:

[0034] (1) The processor receives the respiratory pressure signal and the respiratory flow signal, and obtains a pulse-respiration superimposed wave pressure curve as shown in Figure 3 and a pulse-respiration superimposed wave flow curve as shown in Figure 4 The abscissa of the pulse-respiration wave superimposed pressure curve is the sampling data length, and the ordinate is the data collected by the pressure sensor in the respiratory circuit under the action of the oscillating air flow; the abscissa of the pulse-respiration wave superimposed flow curve is the sampling data length, and the ordinate is the data collected by the flow sensor in the respiratory circuit under the action of the oscillating air flow; the sampling data length is the product of the sampling duration and the sampling frequency, the sampling duration is 30 to 90 seconds, and the sampling frequency is 128 to 1000 Hz;

[0035] (2) Referring to Figure 5 and Figure 6 respectively, perform spline curve fitting on the pulse-respiration superimposed wave pressure curve and the pulse-respiration superimposed wave flow curve to obtain an interference pressure curve and an interference flow curve;

[0036] (3) Remove the interference pressure curve from the pulse-respiration superimposed wave pressure curve to obtain a pulse pressure curve as shown in Figure 7 ; remove the interference flow curve from the pulse-respiration wave superimposed flow curve to obtain a pulse flow curve as shown in Figure 8 ;

[0037] (4) Determine the respiratory impedance according to the pulse pressure curve and the pulse flow curve, including respiratory resistance and respiratory reactance.

[0038] In the present invention, the interference pressure curve and the interference flow curve obtained by spline curve fitting are actually the respiratory waves of the subject. After removing the corresponding respiratory waves from the pressure curve and the flow curve obtained by the processor receiving the real-time detection data of the pressure sensor and the flow sensor, the pulse wave generated by the subject in response to the oscillating air flow can be obtained. This detection result is more accurate and can truly reflect the thoracic and pulmonary health status of the subject.

[0039] In step (2), preferably, each pulse signal of the oscillator is used to segment the pulse-respiration superimposed wave pressure curve and the pulse-respiration superimposed wave flow curve, and spline curve fitting is respectively performed on each segment of the pulse-respiration superimposed wave pressure curve and the pulse-respiration superimposed wave flow curve.

[0040] Specifically, it means segmenting according to the starting point and ending point of each pulse signal; that is, the starting point of the positive voltage signal of the oscillator corresponds to the starting point of the pulse-breathing superimposed wave pressure curve and the pulse-breathing superimposed wave flow curve in time; the ending point corresponds to the ending point of the pulse-breathing superimposed wave pressure curve and the pulse-breathing superimposed wave flow curve in time.

[0041] Since the breathing parameters generated under each pulse wave are all special, the detection result can be made more accurate through segmented fitting.

[0042] In the step (4), the specific method for calculating the respiratory impedance through the above pulse pressure curve and pulse flow curve is as follows:

[0043] The pressure is Fourier-transformed to obtain the real part Ap and the imaginary part Bp; the flow is Fourier-transformed to obtain the real part Av and the imaginary part Bv; the auto-spectrum and cross-spectrum of the pressure p and the flow v in the curve are calculated, where the auto-spectrum ; the cross-spectrum ; the impedance Z( f ) = / = R + jX; the impedance angle θ = -tg -1 (AvBp - ApBv) / (AvAp + BvBp); and then the respiratory resistance R = Zcos(θ); the respiratory reactance X = Zsin(θ).

[0044] In the first embodiment of the present invention, according to the above method, a pulse respiratory resistance-frequency curve as shown in Figure 9 and a pulse respiratory reactance-frequency curve as shown in Figure 10 are obtained; the pulse respiratory resistance-frequency curve and the pulse respiratory reactance-frequency curve can truly reflect the breathing condition of the subject in response to the oscillating air flow.

[0045] Table 1 calculates and respectively compares the errors of the standard respiratory resistance-frequency curve, the respiratory resistance-frequency curve obtained by the method of the present application, and the respiratory resistance-frequency curve fitted by the conventional moving average filtering in the prior art, and the errors of the standard respiratory reactance-frequency curve, the respiratory reactance-frequency curve obtained by the method of the present application, and the respiratory reactance-frequency curve fitted by the conventional moving average filtering in the prior art. It can be clearly seen that the errors between the respiratory resistance and respiratory reactance obtained by the method in the present application and the standard curve are smaller, and the detection result is more accurate.

[0046] Table 1 Figure 9 and Figure 10 Error comparison of each curve in

[0047]

[0048] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for detecting pulse oscillation respiratory impedance, characterized in that, Including the following steps: S1. Generate an oscillating air flow at a fixed frequency f, collect the respiratory pressure and respiratory flow data of the subject respectively, and obtain the pulse-respiration superimposed wave pressure curve and the pulse-respiration superimposed wave flow curve of the subject; the abscissa of the pulse-respiration superimposed wave pressure curve and the pulse-respiration superimposed wave flow curve is the sampling data length, and the ordinates are the collected respiratory pressure data and respiratory flow data respectively; the sampling data length is the product of the sampling duration and the sampling frequency, the sampling duration is 30 to 90 seconds, and the sampling frequency is 128 to 1000 Hz; S2. Perform spline curve fitting on the pulse-respiration superimposed wave pressure curve and the pulse-respiration superimposed wave flow curve respectively to obtain an interference pressure curve and an interference flow curve, and the interference pressure curve and the interference flow curve are respectively used to characterize the pressure signal and the respiratory flow signal of the subject's respiratory wave; S3. Remove the interference pressure curve from the pulse-respiration superimposed wave pressure curve to obtain a pulse pressure curve; Remove the interference flow curve from the pulse-respiration superimposed wave flow curve to obtain a pulse flow curve; S4. Determine the respiratory impedance according to the pulse pressure curve and the pulse flow curve.

2. The pulse oscillation respiratory impedance detection method according to claim 1, characterized in that The step S2 is: segment the pulse-respiration superimposed wave pressure curve and the pulse-respiration superimposed wave flow curve according to each pulse signal of the oscillating air flow, and perform spline curve fitting on each segmented pulse-respiration superimposed wave pressure curve and pulse-respiration superimposed wave flow curve respectively.

3. The pulse oscillation respiratory impedance detection method according to claim 2, characterized in that, The method of fitting according to the pulse time period of the oscillating air flow is: the starting time point of the positive signal of the pulse oscillation voltage signal corresponds to the starting time point of the positive pulse of the pulse-respiration superimposed wave, and the ending time point of the positive signal of the pulse oscillation voltage signal corresponds to the ending time point of the positive pulse of the pulse-respiration superimposed wave; the starting time point of the negative signal of the pulse oscillation voltage signal corresponds to the starting time point of the negative pulse of the pulse-respiration superimposed wave, and the ending time point of the negative signal of the pulse oscillation voltage signal corresponds to the ending time point of the negative pulse of the pulse-respiration superimposed wave.

4. The pulse oscillation respiratory impedance detection method according to claim 3, wherein During the spline curve fitting of the pulse wave, the fitting direction of the spline curve is guided by the midpoint of the time interval between the previous pulse and the current pulse and the next pulse and the current pulse.

5. The pulse oscillation respiratory impedance detection method according to claim 1, characterized in that Determine the pulse respiratory resistance-frequency curve and the pulse respiratory reactance-frequency curve according to the pulse pressure curve and the pulse flow curve, and determine the respiratory impedance from the pulse respiratory resistance-frequency curve and the pulse respiratory reactance-frequency curve.

6. A pulse oscillation respiratory impedance detection system, characterized in that, Used to detect the respiratory impedance of the subject, the respiratory impedance includes respiratory resistance and respiratory reactance, and is characterized by including: An oscillator for generating an oscillating air flow with a fixed frequency of f to the airway of the subject, where f is 1 to 3 Hz; A pressure sensor for detecting the respiratory pressure of the airway of the subject; A flow sensor for detecting the respiratory flow of the airway of the subject; A processor, the processor is connected to the pressure sensor and the flow sensor and receives the respiratory pressure and respiratory flow signals; A storage unit stores multiple instructions, and when the instructions are executed by the processor, the processor executes the pulse oscillation respiration impedance detection method according to any one of claims 1 to 4.

7. The pulse oscillation respiratory impedance detection system according to claim 6, wherein The pulse oscillation respiration impedance detection system includes a breathing circuit that communicates with the subject's mouth and the atmospheric environment, and the flow sensor and the pressure sensor are arranged in the breathing circuit; the oscillator is an external loudspeaker for generating an oscillating air flow to the subject.

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