CN104473647A - Wireless forced oscillation pulmonary impedance tester and testing method thereof - Google Patents

Abstract

The invention relates to a medical treatment detection instrument, in particular to a wireless forced oscillation pulmonary impedance tester and a testing method of the tester. The invention adopts the technical scheme as follows: the wireless forced oscillation pulmonary impedance tester comprises a singlechip microcomputer, a DAC (digital-to-analog converter) module unit, a power amplification unit, a pressure measurement unit, a flow measurement unit, a filter circuit unit, an ADC (analog-to-digital converter) module unit, a single-frequency mode unit, a complex-frequency mode unit, a wireless transmission unit and a receiving, storing and display unit of an upper computer. According to the technical scheme, the single-frequency mode and the complex-frequency mode are additionally set for measurement, so that the defect that the existing instrument is used for measuring only in a single mode can be overcome, and the application scope of the oscillation pulmonary impedance tester is wider; furthermore, the tester is connected with a wireless transmission module, so that the test results are effectively and directly transmitted into the upper computer of a doctor, and the doctor can conveniently search the results; after the wireless forced oscillation pulmonary impedance tester and the testing method of the tester are adopted, a patient is not limited by the place, and can be measured at any time and any place, so that the medical treatment cost and the time cost of the patient are greatly lowered.

Description

A kind of wireless forced oscillation lung impedance instrument and method of testing thereof

Technical field

The present invention relates to medical detecting Instrument, refer to a kind of wireless forced oscillation lung impedance instrument and method of testing thereof especially.

Background technology

Vibration lung impedance instrument applies to widely measure lung resistance value in domestic and mini clinic, and existing vibration lung impedance instrument only has simple single frequency mode or multifrequency pattern at this block of measurement, can not use comprehensively, make the scope of application of this vibration lung impedance instrument narrower; And existing vibration lung impedance instrument cannot realize measurement data and doctor to realize transmitting, patient must obtain specific place and could measure, and adds patient medical and time cost.

Summary of the invention

For the deficiency that prior art exists, the object of the present invention is to provide and a kind of there is single frequency mode and multifrequency pattern, measurement data directly can be sent on the long-range host computer of doctor, reduce wireless forced oscillation lung impedance instrument and the measuring method thereof of patient medical and time cost.

The feature of wireless forced oscillation lung impedance instrument for the present invention is: comprise

Single-chip microcomputer;

Oscillator signal generation unit, produces the oscillator signal of characteristic frequency and amplitude;

Power amplification unit, oscillator signal amplifies through power amplification circuit, excitation loudspeaker vibration, and loudspeaker vibration promotes gas motion and produces the larger oscillating air flow of vibration pressure, enters the oral cavity of experimenter and is superimposed upon on respiratory air flow;

Pressure measurement cell, measures and absorbs and the oscillation pressure reflected through air flue and lung tissue, produces oscillation pressure analogue signal;

Airflow measurement unit, measures and absorbs and the vibration flow reflected through air flue and lung tissue, produces vibration flow analog signals;

Filter circuit unit, filters the oscillation pressure signal and vibration flow signal that are subject to external interference;

ADC module converts unit, changes into oscillation pressure digital signal and vibration flow digital signal by oscillation pressure analogue signal and vibration flow analog signals;

Single frequency mode unit comprises extraction unit, carries out mobile filter computing, obtain respiratory component to this signal obtained within a cycle of oscillation, and extracts wave of oscillation composition from being deducted respiratory component by primary signal; Arithmetic element, carries out mutual dry method computing by the wave of oscillation composition extracted.

Multifrequency mode unit comprises Fourier transform unit, carries out to this signal obtained the array that fast Fourier transform obtains being made up of the real part of each frequency quantity and imaginary part; Extraction unit, for the transformation results of this Fourier transform unit, from array, go out real part and the imaginary part of each frequency quantity according to its corresponding subscript sequential extraction procedures, this real part in frequency spectrum and imaginary part deduct this approximate breathing radio-frequency component, just can take out wave of oscillation composition; Arithmetic element, is undertaken being transformed into power spectrum by oscillationg component, calculates the G of this point _pPand G _qP, use G _pPdivided by G _qP, obtain amplitude Z, and lung impedance parameter can be calculated by the corresponding phase angular dimensions of trying to achieve; And

Wireless transmission unit, by test data by GPRS transmission to host computer.

Host computer receiving element, receives the carrying out of uploading, preserve and shows.

At wireless forced oscillation lung impedance instrument for the present invention, it is characterized in that: also comprise power circuit, this power circuit comprises toroidal transformer, civil power 220V is converted to the alternating voltage of 26V by one outfan of toroidal transformer, more stable output supplies power amplification circuit at positive and negative 34V after rectifier circuit rectification; Civil power 220V is converted to the alternating voltage of 15V by another outfan of toroidal transformer, then after rectifier circuit rectification, stablizes output at positive and negative 12V for single chip circuit.

In the method for testing of wireless forced oscillation lung impedance instrument of the present invention, it is characterized in that: comprising:

Single-chip microcomputer;

Oscillator signal generating step, produces the oscillator signal of characteristic frequency and amplitude;

Power amplifying step, oscillator signal amplifies through power amplification circuit, excitation loudspeaker vibration, and loudspeaker vibration promotes gas motion and produces the larger oscillating air flow of vibration pressure, enters the oral cavity of experimenter and is superimposed upon on respiratory air flow;

Pressure measxurement step, measures and absorbs and the oscillation pressure reflected through air flue and lung tissue, produces oscillation pressure analogue signal;

Flux measuring step, measures and absorbs and the vibration flow reflected through air flue and lung tissue, produces vibration flow analog signals;

Filter step, filters the oscillation pressure signal and vibration flow signal that are subject to external interference;

ADC module converts step, changes into oscillation pressure digital signal and vibration flow digital signal by oscillation pressure analogue signal and vibration flow analog signals;

After above-mentioned steps, single frequency mode unit or multifrequency mode unit is optionally selected to test;

Single frequency mode step comprises extraction step, carries out mobile filter computing, obtain respiratory component to this signal obtained within a cycle of oscillation, and extracts wave of oscillation composition from being deducted respiratory component by primary signal; Arithmetic element, carries out mutual dry method computing by the wave of oscillation composition extracted.

Multifrequency mode step comprises Fourier transformation step, carries out to this signal obtained the array that fast Fourier transform obtains being made up of the real part of each frequency quantity and imaginary part; Extraction step, for the transformation results of this Fourier transform unit, from array, go out real part and the imaginary part of each frequency quantity according to its corresponding subscript sequential extraction procedures, this real part in frequency spectrum and imaginary part deduct this approximate breathing radio-frequency component, just can take out wave of oscillation composition; Calculation step, is undertaken being transformed into power spectrum by oscillationg component, calculates the G of this point _pPand G _qP, use G _pPdivided by G _qP, obtain amplitude Z, and lung impedance parameter can be calculated by the corresponding phase angular dimensions of trying to achieve; And

Wireless transmission step, by test data by GPRS transmission to host computer;

Host computer receiving step, receives the carrying out of uploading, preserve and shows;

Each above-mentioned steps is performed in single-chip microcomputer process, control.

By adopting technique scheme, adding two groups of single frequency mode and multifrequency pattern is measured, overcoming in existing instrument and only having single-mode to carry out the mode measured, making the scope of application of this vibration lung impedance instrument wider; And wireless transport module is connected on instrument, can effectively test result directly be transferred on the host computer of doctor, be convenient to doctor's inquiry, patient, without the need to being subject to the restriction in place, just can measure whenever and wherever possible, substantially reduces patient medical and time cost.

According to this invention, larger energy is needed because speaker promotes air-flow, here the alternating voltage using toroidal transformer the 220V civil power of outside to be converted to 26V stablizes output again at positive and negative about 34V after GBJ2510 rectifier circuit, for unidirectional current for amplifying circuit, ensure that oscillating air flow has larger vibration pressure.

Accompanying drawing explanation

In order to be illustrated more clearly in the embodiment of the present invention or technical scheme of the prior art, be briefly described to the accompanying drawing used required in embodiment or description of the prior art below, apparently, accompanying drawing in the following describes is only some embodiments of the present invention, for those of ordinary skill in the art, under the prerequisite not paying creative work, other accompanying drawing can also be obtained according to these accompanying drawings.

Fig. 1 is specific embodiment of the invention system architecture diagram;

Fig. 2 is power circuit in the specific embodiment of the invention

Fig. 3 is specific embodiment of the invention instrument system illustraton of model;

Fig. 4 is the cause effect relation figure of oscillation pressure and vibration flow in the specific embodiment of the invention;

Fig. 5 is about moving average filtering method is used for breath signal that filtering collects to extract the flow chart of forced oscillation signal in the specific embodiment of the invention;

Fig. 6 is about the flow chart forced oscillation signal extracted being carried out mutual dry method of the invention process in the specific embodiment of the invention;

Fig. 7 will filter out an algorithm schematic diagram of the breathing high-frequency signal be mixed into about of the invention process in the specific embodiment of the invention in the spectrum signal obtained;

Fig. 8 is that the sine wave being spaced apart 1Hz about multifrequency sinusoidal signal by 1-20Hz in the specific embodiment of the invention forms schematic diagram;

Fig. 9 is about single frequency sinusoidal signal is by the sinusoidal wave schematic diagram of 5Hz in the specific embodiment of the invention;

Figure 10 is that after representing and uploading the data to host computer by respiratory impedance system for the present invention, parameter display interface under multifrequency wherein comprises spectrum analysis figure and parameter thereof;

Figure 11 is after representing and uploading the data to host computer by respiratory impedance system for the present invention, the Rrs-Time figure that the parameter display interface under single-frequency wherein comprises;

Figure 12 is after representing and uploading the data to host computer by respiratory impedance system for the present invention, the Xrs-Time figure that the parameter display interface under single-frequency wherein comprises;

Figure 13 represents Rrs-Time and the Xrs-Time figure tested under single frequency mode by respiratory impedance system for the present invention;

Figure 14 represents the spectrum analysis figure tested under multifrequency pattern by respiratory impedance system for the present invention.

Detailed description of the invention

Below in conjunction with the accompanying drawing in the embodiment of the present invention, be clearly and completely described the technical scheme in the embodiment of the present invention, obviously, described embodiment is only the present invention's part embodiment, instead of whole embodiments.Based on the embodiment in the present invention, those of ordinary skill in the art, not making the every other embodiment obtained under creative work prerequisite, belong to the scope of protection of the invention.

As shown in Fig. 1-Figure 14, the invention discloses wireless forced oscillation lung impedance instrument, in the specific embodiment of the invention,

Single-chip microcomputer 1, the model of single-chip microcomputer is STM32, with STM32 single-chip microcomputer for main control chip, controls the collection of respiratory flow signal, process, display and wireless transmission;

Oscillator signal generation unit, produces the oscillator signal of characteristic frequency and amplitude, and wherein oscillator signal generation unit adopts DAC module unit 2;

Power amplification unit, oscillator signal amplifies through power amplification circuit 3, and excitation speaker 4 vibrates, and loudspeaker vibration promotes gas motion and produces the larger oscillating air flow of vibration pressure, enters the oral cavity of experimenter and is superimposed upon on respiratory air flow;

Pressure measurement cell 5, measures and absorbs and the oscillation pressure reflected through air flue and lung tissue, produces oscillation pressure analogue signal;

Airflow measurement unit 6, measures and absorbs and the vibration flow reflected through air flue and lung tissue, produces vibration flow analog signals;

Filter circuit unit, filter circuit unit adopts low pass filter 10, the oscillation pressure signal and vibration flow signal that are subject to external interference is filtered;

ADC module converts unit 7, changes into oscillation pressure digital signal and vibration flow digital signal by oscillation pressure analogue signal and vibration flow analog signals;

After above-mentioned steps, selection single frequency mode unit or the multifrequency mode unit of selecting property of patient-selectable are tested;

Single frequency mode unit 9: the frequency produced by above-mentioned DAC unit be 5Hz single frequency sinusoidal oscillator signal by power amplification unit rear drive speaker after, measure the signal obtaining being obtained by above-mentioned pressure sensing cell and above-mentioned flow detection unit, extraction unit 11, within a cycle of oscillation, mobile filter computing is carried out to this signal obtained, obtain respiratory component, and extract wave of oscillation composition from being deducted respiratory component by primary signal; Arithmetic element 12, carries out mutual dry method computing by the wave of oscillation composition extracted, and adopts following formula to calculate

$A_t=\frac{2}{N}{\mathrm{\Σ}}_{t_1-\frac{2}{N}}^{t_1+\frac{2}{N}}P\left(t_1\right)\sin \left(\frac{2{\mathrm{\πt}}_1}{N}\right),B_t=\frac{2}{N}{\mathrm{\Σ}}_{t_1-\frac{2}{N}}^{t_1+\frac{2}{N}}P\left(t_1\right)\cos \left(\frac{2{\mathrm{\πt}}_1}{N}\right)$

${\left|P\right|}_t=\sqrt{{A_t}^2+{B_t}^2},\mathrm{\θ}\left(P_t\right)=\arctan \left(\frac{B_t}{A_t}\right)$

Because respiratory system can be considered to approximately linear system, the cause effect relation that the input (oscillation pressure) of system and output (vibration flow) have, therefore the amplitude of vibration flow | Q| _twith phase theta (Q _t) also can with reference to above-mentioned formulae discovery out.By formula

${\left|Z\right|}_t=\frac{{\left|P\right|}_t}{{\left|Q\right|}_t},$

Corresponding respiratory resistance and phase information can be calculated.

Can be obtained by polar coordinate formula:

Obtain Rrs, Xrs and Zrs (lung impedance parameter) over time, and obtains its meansigma methods and obtains lung impedance parameter.

Computational methods are as follows: optimum linearity method of approximation

Calculate respiratory resistance and require that pressure and flow meet linear relationship, but respiratory system is neither a linear system, stable state neither be in always, mechanical characteristics with the normal functional state of disease or people, Pulmonary volume, gas flow rate and muscle the change of the variable such as tensity and different, therefore a correct measurement method is needed (to loosen during test, eupnea) to get rid of the tight impact caused of muscle, make the operating point of respiratory system only be subject to the impact of Pulmonary volume and gas flow rate.Therefore last these two parameters of respiratory resistance reason are expressed.If above-mentioned variable is carried out mark, utilize the method that optimum linearity is approximate, the resistance of the respiratory system that still can obtain approx.Assuming that breathing is a linear approximation system, pulmonary mechanics feature keeps relative stable, the input (oscillation pressure) of system and the cause effect relation exporting (vibration flow) and have, as shown in Figure 4.Suppose that the pressure signal inputted is for sinusoidal wave

p _op(ft)＝|p| _f.opsin(2πft+∠p _f.op)

Supposing the system is linear, then corresponding output flow signal also can be sinusoidal form

q _op(ft)＝|q| _f.opsin(2πft+∠p _f.op))

Both relations can utilize transfer function to be expressed as:

$Z_{f.\mathrm{op}}=\frac{p_{\mathrm{op}}\left(\mathrm{ft}\right)}{q_{\mathrm{op}}\left(\mathrm{ft}\right)}$

Wherein, f represents the frequency of forced oscillation, op represents operating point, t is the time, Z is respiratory system total impedance, p and q represents oscillation pressure and vibration flow respectively, and p (ft) and q (ft) be then oscillation pressure and the function of flow signal that vibrates, the information containing amplitude and phase place.In mathematics, vector is made up of real part and imaginary part, clinically we | Z| is defined as Zrs, and real part is defined as respiratory impedance Rrs, and imaginary part is defined as breathes reactance Xrs.

Z＝Rrx+jXrs

According to the model that Horowitz etc. provides, respiratory system can be thought and to be made up of controlled low frequency air flow source Qrs (t) and time dependent impedance Z resp (t), and lung impedance instrument can think that the impedance Z 2 of the breathing pipeline that the respiratory impedance Z1 being connected pipeline with oscillation source by controlled high-frequency pressure source Pap (ft), experimenter is connected with the external world with experimenter forms.Its structure chart is as shown under Fig. 3:

Illustrate: wherein $\begin{array}{cc}Q\left(t\right)=\frac{\mathrm{Zresp}\left(t\right)}{\mathrm{Zresp}\left(t\right)+Z1+Z2}\mathrm{Qrs}\left(t\right)& p(t,\mathrm{ft})=\frac{\mathrm{Zresp}\left(t\right)}{\mathrm{Zresp}\left(t\right)+Z1}{p}_{\mathrm{ap}}\left(\mathrm{ft}\right)\\ P\left(t\right)=(Z1+Z2)Q\left(t\right)& q(t,\mathrm{ft})=\frac{1}{\mathrm{Zresp}\left(t\right)+Z1}{p}_{\mathrm{ap}}\left(\mathrm{ft}\right)\end{array}$

Although p (t, ft) and q (t, ft) has the impact by oscillation source and respiratory system, the value after they be divided by is only only by the impact of respiratory impedance Zrs.The pressure wherein recorded and flow P (t, ft) and Q (t, ft) represent, Q (t) represents the respiratory flow produced by people, and P (t) represents by the pressure drop of Q (t) in Z1, Z2 generation.

Q(t,ft)＝Q(t)+q(t,ft)

P(t,ft)＝P(t)+p(t,ft)

Therefore in order to measure respiratory impedance, need artificial breath signal to separate.Now use moving average filtering method respiratory signal data and oscillator signal data separating to be opened, and obtain oscillator signal.

The meansigma methods of the pressure signal of one-period is represented then with < P (t ", ft) >

$<P(t^{\&prime;\&prime;},\mathrm{ft})>=\frac{1}{T}{\&Integral;}_{t^{\&prime;\&prime;}-\frac{T}{2}}^{t^{\&prime;\&prime;}+\frac{T}{2}}P(t,\mathrm{ft})\mathrm{dt}$

Because the integration of a sine wave within the cycle is 0, therefore < P (t "; ft) >=< P (t ") >, so the forced oscillation signal t " estimated value in moment other are each by that analogy, thus general breathing and forced oscillation Signal separator can be come.Due to single-chip microcomputer can only processing digital signal thus need become single-chip microcomputer to process above-mentioned mathematical theory method migration method.

Moving average filtering and mutual dry method

Artificial breath signal has been mixed in initial data due to collection, for eliminating the impact that respiratory component calculates respiratory impedance, oscillation pressure and vibration flow composition is needed to separate from the primary signal after low-pass filtering, we adopt moving average filtering (moving average filtering) technology, namely carrying out data sum-average arithmetic time window window length to the signal in finite time is a sampling number comprised cycle of oscillation, obtain new numerical value after subtracting each other by the sampled value after original sampled value and average filter, principle as shown in Figure 5.

Mutual dry method is with the discrete Fourier series of discrete series for theoretical basis, is similar to the Fourier space replacing first-harmonic and each harmonic and first-harmonic with the Fourier space of its fundametal compoment.Its step applying to respiratory system is as follows: first define the long time window for cycle of oscillation of a window.Use the sample frequency of 100Hz and the frequency of oscillation of 5Hz herein, therefore have N=20 sampled point in the cycle of oscillation.Be defined as at t1 moment time window:

$A_t=\frac{2}{N}{\mathrm{\&Sigma;}}_{t_1-\frac{2}{N}}^{t_1+\frac{2}{N}}P\left(t_1\right)\sin \left(\frac{2{\mathrm{\&pi;t}}_1}{N}\right),B_t=\frac{2}{N}{\mathrm{\&Sigma;}}_{t_1-\frac{2}{N}}^{t_1+\frac{2}{N}}P\left(t_1\right)\cos \left(\frac{2{\mathrm{\&pi;t}}_1}{N}\right)$ Therefore at the oscillation signal amplitude in t1 moment and phase place be:

${\left|P\right|}_t=\sqrt{{A_t}^2+{B_t}^2},\mathrm{\&theta;}\left(P_t\right)=\arctan \left(\frac{B_t}{A_t}\right)$

Because respiratory system can be considered to approximately linear system, the cause effect relation that the input (oscillation pressure) of system and output (vibration flow) have, therefore the amplitude of vibration flow | Q| _twith phase theta (Q _t) also can with reference to above-mentioned formulae discovery out.By formula

${\left|Z\right|}_t=\frac{{\left|P\right|}_t}{{\left|Q\right|}_t},$

Corresponding respiratory resistance and phase information can be calculated.

Can be obtained by polar coordinate formula:

Can calculate Rrs and Xrs in each moment according to above-mentioned formula, principle as shown in Figure 6.

Multifrequency algorithm

Multifrequency mode unit comprises Fourier transform unit 15, the frequency produced by above-mentioned DAC unit be 1-20Hz be spaced apart 1Hz multifrequency pure oscillation signal by power amplification unit rear drive speaker after, under measuring the pressurized state produced, obtain the signal obtained by above-mentioned pressure sensing cell and above-mentioned flow detection unit, and the array that fast Fourier transform then can obtain being made up of the real part of each frequency quantity and imaginary part is carried out to this signal obtained, extraction unit 13, for the transformation results of this Fourier transform unit, go out real part and the imaginary part of each frequency quantity according to its corresponding subscript sequential extraction procedures from array, due to certain breathing radio-frequency component can be mixed in oscillationg component, in order to avoid breathing the impact of radio-frequency component, here approximate substitution method is adopted, namely be added to be averaged carry out the breathing radio-frequency component of approximate substitution in this frequency quantity divided by 2 again by the turn left real part of second Frequency point and second Frequency point of turning right and imaginary signals of the corresponding subscript of the frequency quantity that will extract, this approximate breathing radio-frequency component is deducted with the real part of this in frequency spectrum and imaginary part, just can take out wave of oscillation composition, arithmetic element 14, is undertaken being transformed into power spectrum by oscillationg component, calculates the G of this point _pP(spectrum certainly of respiratory pressure) and G _qP(cross-spectrum of respiratory pressure and flow), uses G _pPdivided by G _qP, obtain amplitude Z, and can calculate lung impedance parameter by the corresponding phase angular dimensions of trying to achieve, specific implementation process is as follows:

Produce complex frequency signal with STM32 and promote speaker, producing the forced oscillation barometric wave of multi-frequency compound, afterwards by being fourier transformed on frequency domain, various analysis being carried out to the pressure recorded, flow signal, the amplitude of such as signal, phase place and power analysis etc.Mathematical tool room fast Fourier transform FFT is used in multifrequency Algorithm Analysis.

The Fourier of function x (t) of a time domain change changes F (jw) and is:

$\begin{array}{cc}F\left(\mathrm{jw}\right)={\&Integral;}_{-\&infin;}^{\&infin;}x\left(t\right)e^{-\mathrm{jwt}}\mathrm{dt}=R\left(w\right)+\mathrm{jX}\left(w\right)& (w=2^{\mathrm{\&pi;f}})\end{array}$

In formula, x (t) is time-domain function, and F (jw) is frequency-domain function, the real part that R (w) changes for Fourier, the imaginary part that X (w) changes for Fourier.

For the single system be made up of input pressure P (t) and output flow velocity V (t), its transfer function H is:

For deterministic signal, namely input pressure P (t) is flow signal V (t) of the signal fixing change in time, its mechanism, then respiratory impedance Zrs is:

$\mathrm{Zrs}=\frac{1}{H}=\frac{F_q}{F_P}=\frac{A_q+{\mathrm{jB}}_p}{A_q+{\mathrm{jB}}_q}$

For stochastic signal, namely input voltage signal P (t) is pseudo-random signal, this just relates to the factor problems such as synchronous and statistics, therefore said method is utilized to calculate Zrs infeasible, introduce power spectrum (powerspectra), the frequency spectrum real part of pressure and flow signal is respectively Ap (fk), Aq (fk) for this reason, imaginary part is respectively Bp (fk), Bq (fk).

G _PP＝(A _P+jB _P)(A _P-jB _P)＝A _P ²+B _P ²

G _QQ＝(A _Q+jB _Q)(A _Q-jB _Q)＝A _Q ²+B _Q ²

G _QP＝(A _QA _P+B _QB _P)+j(A _pB _Q-jB _pA _Q)

In formula: G _pP--the spectrum certainly of respiratory pressure; G _qQ--the spectrum certainly of respiratory flow; G _qP--the cross-spectrum of respiratory pressure and flow; Real part after A-FFT; Imaginary part coefficient after B-FFT; After using power spectrum, amplitude and the phase angle of impedance are obtained by following formula:

$Z\left(f_k\right)=\frac{G_{\mathrm{PP}}}{\left|G_{\mathrm{QP}}\right|}=\frac{{A_P}^2+{B_P}^2}{\sqrt{(A_Q{A}_P+B_Q{B}_P)+j(B_Q{A}_P-A_Q{B}_P)}}$

$\mathrm{\&theta;}\left(f_k\right)=-\arctan \left(\frac{(A_P{B}_Q-B_P{A}_Q)}{(A_P{A}_Q+B_P{B}_Q)}\right)$

By this method calculate Zrs a little: the character of input pressure P (t) is not depended in the calculating of Zrs.Respiratory impedance R (fk) can be obtained thus and breathe reactance X (fk)

R(f _k)＝|Z(f _k)|cosθ(f _k),X(f _k)＝|Z(f _k)|sinθ(f _k)

As shown in Figure 7, ADC gathers the data of flow and pressure transducer with the sample frequency of 128Hz, and is left in array.Deng collection terminate the rear data to collecting carry out base 4 fast Fourier change, then can obtain the array be made up of the real part of each frequency quantity and imaginary part, and go out real part and the imaginary part of each frequency quantity according to its corresponding subscript sequential extraction procedures from array.Due to certain breathing radio-frequency component can be mixed in oscillationg component, in order to avoid breathing the impact of radio-frequency component, here adopt approximate substitution method, namely with the second signal addition that namely vicinity of frequency quantity is turned left and turned right be averaged afterwards approximate substitution at the breathing radio-frequency component of this frequency quantity.Deduct this breathing radio-frequency component with this point in frequency spectrum, just can take out wave of oscillation composition.

The oscillating part signal recorded is transformed on power spectrum and is analyzed, the lung impedance parameter of respective frequencies point can be drawn.

During spectrum analysis technique application with biosystem, owing to there is the noise jamming that autonomous respiration source etc. has nothing to do when measuring respiratory pressure and flow signal, therefore also should introduce frequency domain correlation function r ²(Coherencefunction) also need the calculating (r2) carrying out coherent function with the reliability of demo plant.

$r^2=\frac{{\left|G_{\mathrm{QP}}\right|}^2}{G_{\mathrm{PP}}{G}_{\mathrm{QQ}}}$

Coherent function r ²be the index characterizing linear system input, output relation, r2 value is between 0 ~ 1:

1. r ²then show when=1 that system is not subject to noise jamming;

2. r ²=0 shows to export and input to have nothing to do;

3. 0<r ²represent during <1 that between input and output, existing being correlated with exists interference again; During usual r2>0.95, measured resistance value is just thought reliably; By Spectral Analysis Method, respiratory impedance can be made on multi-frequency once to complete measurement, do not need the cooperation of experimenter, greatly improve the testing efficiency of respiratory impedance;

And wireless transmission unit 16, by test data by GPRS transmission to host computer, wherein radio universal packet wireless business (GPRS) is a kind of new packet data bearers business developing out on existing gsm system, provides to connect end to end to be connected with the wireless IP of wide area.The GPRS that system adopts is the SIM900A module of SIMCom company, and this module volume is little, low in energy consumption, embedded ICP/IP protocol.The physical interface of STM32 processor and wireless module is RS232, can complete operation to module by sending corresponding " AT " instruction.

Host computer 17 receiving element, with visual studio 2010 software and sql server 2008 software programming host computer procedure, receives the carrying out of uploading, preserve and shows.

Wherein, also comprise power circuit, this power circuit comprises toroidal transformer, and civil power 220V is converted to the alternating voltage of 26V by an outfan of toroidal transformer, after rectifier circuit rectification, stable output supplies power amplification circuit at positive and negative 34V again, resupplies and uses to speaker; Civil power 220V is converted to the alternating voltage of 15V by another outfan of toroidal transformer, stablize after rectifier circuit rectification again and export at positive and negative 12V, again through manostat by Control of Voltage at sound of sighing 3.3V for single-chip microcomputer, wherein manostat employing ASM1117 is serial.

Very large energy is needed owing to promoting air-flow, here the alternating voltage using toroidal transformer the 220V civil power of outside to be converted to 26V again after GBJ2510 rectifier circuit stable output at positive and negative about 34V, for unidirectional current for amplifying circuit, produce Sasser to make the low level signal amplification of input to drive speaker.

XL1509 Switching Power Supply is used to be become by the photovoltaic conversion of input stable 5V output voltage to be used for flow transducer, pressure transducer, GPRS and liquid crystal.Because STM32 rated operational voltage is 3.3V voltage, the manostat that model is ASM1117 is used to become 3.3V for single-chip microcomputer stable 5V photovoltaic conversion here.

Wherein this single-chip microcomputer is also connected with SD interface, also measurement data is stored, effectively achieve the movement of data, single-chip microcomputer is also connected with liquid crystal touch display screen, be convenient to patient's operation, be also convenient to this joint of patient by liquid crystal touch display screen read test data.

By adopting technique scheme, adding two groups of single frequency mode and multifrequency pattern is measured, overcoming in existing instrument and only having single-mode to carry out the mode measured, making the scope of application of this vibration lung impedance instrument wider; And wireless transport module is connected on instrument, can effectively test result directly be transferred on the host computer of doctor, be convenient to doctor's inquiry, patient, without the need to being subject to the restriction in place, just can measure whenever and wherever possible, substantially reduces patient medical and time cost.

According to this invention, larger energy is needed because speaker promotes air-flow, here the alternating voltage using toroidal transformer the 220V civil power of outside to be converted to 26V stablizes output again at positive and negative about 34V after GBJ2510 rectifier circuit, for unidirectional current for amplifying circuit, ensure that oscillating air flow has larger vibration pressure.

Experimental result shows that instrument not only can use single frequency mode to follow the trail of respiratory impedance and multifrequency pattern also can be used over time to detect the respiratory impedance in each frequency fast and demonstrate spectrum analysis figure, the UI interface provided provides visualized operation for user, also there is the functions such as remote transmission, realize tele-medicine, can be further study of lung impedance examination instrument and develop on household application market reference is provided.The conventional lung impedance repeatability high reliability measured is good, and whole instrument is small and exquisite, cost is low, is applicable to very much being generalized to basic hospital and patient home's use.

The foregoing is only preferred embodiment of the present invention, not in order to limit the present invention, within the spirit and principles in the present invention all, any amendment done, equivalent replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (3)

1. a wireless forced oscillation lung impedance instrument, is characterized in that: comprise

Single-chip microcomputer;

Oscillator signal generation unit, produces the oscillator signal of characteristic frequency and amplitude;

Power amplification unit, oscillator signal amplifies through power amplification circuit, excitation loudspeaker vibration, and loudspeaker vibration promotes gas motion and produces the larger oscillating air flow of vibration pressure, enters the oral cavity of experimenter and is superimposed upon on respiratory air flow;

Pressure measurement cell, measures and absorbs and the oscillation pressure reflected through air flue and lung tissue, produces oscillation pressure analogue signal;

Airflow measurement unit, measures and absorbs and the vibration flow reflected through air flue and lung tissue, produces vibration flow analog signals;

Filter circuit unit, filters the oscillation pressure signal and vibration flow signal that are subject to external interference;

ADC module converts unit, changes into oscillation pressure digital signal and vibration flow digital signal by oscillation pressure analogue signal and vibration flow analog signals;

Single frequency mode unit comprises extraction unit, carries out mobile filter computing, obtain respiratory component to this signal obtained within a cycle of oscillation, and extracts wave of oscillation composition from being deducted respiratory component by primary signal; Arithmetic element, carries out mutual dry method computing by the wave of oscillation composition extracted.

Multifrequency mode unit comprises Fourier transform unit, carries out to this signal obtained the array that fast Fourier transform obtains being made up of the real part of each frequency quantity and imaginary part; Extraction unit, for the transformation results of this Fourier transform unit, from array, go out real part and the imaginary part of each frequency quantity according to its corresponding subscript sequential extraction procedures, this real part in frequency spectrum and imaginary part deduct this approximate breathing radio-frequency component, just can take out wave of oscillation composition; Arithmetic element, is undertaken being transformed into power spectrum by oscillationg component, calculates the G of this point _pPand G _qP, use G _pPdivided by G _qP, obtain amplitude Z, and lung impedance parameter can be calculated by the corresponding phase angular dimensions of trying to achieve; And

Wireless transmission unit, by test data by GPRS transmission to host computer.

Host computer receiving element, receives the carrying out of uploading, preserve and shows.

2. wireless forced oscillation lung impedance instrument according to claim 1, it is characterized in that: also comprise power circuit, this power circuit comprises toroidal transformer, civil power 220V is converted to the alternating voltage of 26V by one outfan of toroidal transformer, more stable output supplies power amplification circuit at positive and negative 34V after rectifier circuit rectification;

Civil power 220V is converted to the alternating voltage of 15V by another outfan of toroidal transformer, then after rectifier circuit rectification, stablizes output at positive and negative 12V for single chip circuit.

3. a method of testing for wireless forced oscillation lung impedance instrument, comprising:

Single-chip microcomputer;

Oscillator signal generating step, produces the oscillator signal of characteristic frequency and amplitude;

Power amplifying step, oscillator signal amplifies through power amplification circuit, excitation loudspeaker vibration, and loudspeaker vibration promotes gas motion and produces the larger oscillating air flow of vibration pressure, enters the oral cavity of experimenter and is superimposed upon on respiratory air flow;

Pressure measxurement step, measures and absorbs and the oscillation pressure reflected through air flue and lung tissue, produces oscillation pressure analogue signal;

Flux measuring step, measures and absorbs and the vibration flow reflected through air flue and lung tissue, produces vibration flow analog signals;

Filter step, filters the oscillation pressure signal and vibration flow signal that are subject to external interference;

ADC module converts step, changes into oscillation pressure digital signal and vibration flow digital signal by oscillation pressure analogue signal and vibration flow analog signals;

After above-mentioned steps, single frequency mode unit or multifrequency mode unit is optionally selected to test;

Single frequency mode step comprises extraction step, carries out mobile filter computing, obtain respiratory component to this signal obtained within a cycle of oscillation, and extracts wave of oscillation composition from being deducted respiratory component by primary signal; Arithmetic element, carries out mutual dry method computing by the wave of oscillation composition extracted.

Multifrequency mode step comprises Fourier transformation step, carries out to this signal obtained the array that fast Fourier transform obtains being made up of the real part of each frequency quantity and imaginary part; Extraction step, for the transformation results of this Fourier transform unit, from array, go out real part and the imaginary part of each frequency quantity according to its corresponding subscript sequential extraction procedures, this real part in frequency spectrum and imaginary part deduct this approximate breathing radio-frequency component, just can take out wave of oscillation composition; Calculation step, is undertaken being transformed into power spectrum by oscillationg component, calculates the G of this point _pPand G _qP, use G _pPdivided by G _qP, obtain amplitude Z, and lung impedance parameter can be calculated by the corresponding phase angular dimensions of trying to achieve; And

Wireless transmission step, by test data by GPRS transmission to host computer;

Host computer receiving step, receives the carrying out of uploading, preserve and shows;

Each above-mentioned steps is performed in single-chip microcomputer process, control.