CN114224316A - Lung function parameter calculation method based on turbo type lung function instrument - Google Patents

Lung function parameter calculation method based on turbo type lung function instrument Download PDF

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CN114224316A
CN114224316A CN202111351620.6A CN202111351620A CN114224316A CN 114224316 A CN114224316 A CN 114224316A CN 202111351620 A CN202111351620 A CN 202111351620A CN 114224316 A CN114224316 A CN 114224316A
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孙杰
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Zhongke Guangrun Zhongshan Technology Co ltd
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Abstract

The invention discloses a method for calculating lung function parameters based on a turbo type lung function instrument, which comprises the following steps: s10 inputting the collected data to carry out moving average processing to obtain a new data column O (new)n(ii) a S20, removing low threshold data and sparsifying the data; s30 finding a peak point; s40 calculating an adjustment coefficient alpha according to the frequency of the peak pointi(ii) a S50 substitutes data into the following expiratory volume model: compared with the prior art, the invention has the following advantages: on the basis of a steady-state gas turbine flow model theory, the invention provides a frequency coefficient adjusting algorithm based on peak point detection based on a double-blade shaft tip type gas flow turbine. The problem of large calculation error of the expiratory volume is solved, and the acceptability of the volume calculation result is improved.

Description

Lung function parameter calculation method based on turbo type lung function instrument
Technical Field
The invention relates to the technical field of lung function detection equipment, in particular to a method for calculating lung function parameters based on a turbine type lung function instrument.
Background
Chronic Obstructive Pulmonary Disease (COPD) is a common chronic respiratory disease, and according to the world health organization report, COPD is the fourth of the current worldwide mortality diseases. In order to control the disease mortality of COPD, the management of the daily assessment of COPD is of paramount importance, and the powerful lung function test is called the gold standard for COPD diagnosis, while the lung function instrument is a key tool for performing lung function tests. ATS/ERS set forth stringent test criteria for robust lung function, including a start criterion, an end criterion, an acceptance criterion, a repeatable criterion, and the like. The lung function assessment core indexes comprise Forced Vital Capacity (FVC), expiratory peak flow (PEF), maximum expiratory first second (FEV1) and the like, wherein the value of FEV1/FVC is a reliable index directly indicating whether COPD is suffered or not. At present, COPD patients in China are huge in groups, medical resources are relatively tense, and only a part of large hospitals are equipped with lung function instruments, and the use price is high. Therefore, a low-cost and high-precision pulmonary function detection device is urgently needed to share the pressure of families and hospitals. The turbo type lung function instrument has the advantages of high sensitivity, good noise resistance, low cost and the like, and has a very high applicable scene in places such as hospitals and families, and the kernel of the turbo type lung function instrument is mainly the expiratory flow rate measured by a turbo flowmeter, so that the lung function parameters of a patient are obtained by calculating the expiratory flow rate. The conventional turbine flowmeter is a steady-state model, namely a flow calculation model of the turbine is premised on that the turbine is in a constant-speed rotation state. However, the turbine speed will be changed dynamically during the actual test, and thus will generate a large error.
Some existing solutions are a mode of combining a static flow model and a dynamic flow model, and the mode can have good accuracy after calibration for a specific flow sensor, but lacks universality, is complex and cannot be popularized. Or by adding a measuring sensor for turbine rotation to the hardware, the steady-state flow model has two problems: firstly, the forced expiratory signal belongs to a time-varying signal, the existing turbine flow calculation model is a steady-state model, and the relation between the change of the turbine rotation angular frequency and the change of the forced expiratory signal cannot be accurately modeled. Secondly, due to the rotational inertia of the turbine, in the forced lung function test process, the calculation results of the same FVC twice before and after are prone to be deviated due to different flow density distribution in the forced expiration process, and the deviation value is not within an acceptable range. The invention provides a novel lung function parameter calculation model, which solves a large error in expiratory volume by adjusting an algorithm for frequency based on peak point detection, and obtains other lung function parameters based on the algorithm.
Disclosure of Invention
The invention aims to overcome the problems in the prior art and provides a method for calculating lung function parameters based on a turbo type lung function instrument.
In order to achieve the purpose, the invention adopts the following scheme:
a method for calculating lung function parameters based on a turbo type lung function instrument comprises the following steps:
s10 inputting the collected data to carry out moving average processing to obtain a new data column O (new)n；
S20, removing low threshold data and sparsifying the data;
s30 finding a peak point;
s40 calculating an adjustment coefficient alpha according to the frequency of the peak pointi；
S50 substitutes data into the following expiratory volume model:
Figure BDA0003355965080000031
wherein:
Figure BDA0003355965080000032
phi is the flow conversion coefficient of the turbine, N is the number of revolutions of the turbine in 1 test process, alphaiAs the adjustment factor of the frequency point, fiIs the turbine rotation frequency, η is the bias constant;
the forced vital capacity, peak expiratory flow and maximum expiratory first second expiratory volume are calculated.
Further, the step S10 includes:
s11 performs multipoint averaging on the acquired data,
Figure BDA0003355965080000033
wherein: n is the data point, m is the window size, I is the input data point set, OnIs a set of output data points;
s12 establishing a deviation threshold ThNew data column O (new)n，
Figure BDA0003355965080000034
Further, when the new data column O (new)nSatisfy O (new)n-2＜ O(new)n-1＜O(new)n>O(new)n+1>O(new)n+2When τ is 1;
Figure BDA0003355965080000035
further, f in the step S50iThe calculation method of (2) is as follows:
all satisfy O (new)n-2＜O(new)n-1＜O(new)n>O(new)n+1> O(new)n+2Adding the n value of the condition into the sequence P (i) in ascending order, and setting the value range of i at the time as 1, 2, 3 … W;
Figure BDA0003355965080000041
further, in the above-mentioned case,
Figure BDA0003355965080000042
w-1, wherein i ═ 1, 2, 3.; a and B are constants.
A lung function parameter measuring device comprising:
the double-blade shaft tip type turbine comprises a double-blade shaft tip type turbine, wherein photoelectric geminate transistors are arranged at opposite positions on two sides of a turbine of the double-blade shaft tip type turbine and can convert mechanical rotation signals of the turbine into electric signals;
the breathing simulator can generate square wave signals with the flow rate ranging from 1L/sec to 14L/sec, and the breathing simulator can be used for fitting and calibrating the exhalation capacity model and the exhalation flow peak value formula of claim 5 to construct a capacity calculation model based on the square wave signals.
Further, when the flow rate of the blades of the double-blade shaft tip type turbine is 14L/s, the flow resistance is less than 0.15 kPa.L-1·s-1。
Further, the photoelectric pair tube is a side-lying type packaged SIM-012SBT97 infrared photoelectric pair tube, the infrared photoelectric pair tube comprises a transmitting tube and a receiving tube, and the transmitting tube can transmit infrared light with the wavelength of 950 nm.
Further, the photoelectric pair tube is arranged at a size centered position relative to the single-side blade of the turbine.
A method for checking the accuracy of a measuring device according to any of claims 6-9, comprising the steps of:
a, simulating a real forced lung function test by using a calibration barrel, and randomly performing a plurality of groups of gas propulsion experiments with different speeds and different volumes;
b, recording the electric signals output by the sensing mechanism by using a digital oscilloscope, and comparing the number of wave crests or wave troughs detected by the digital oscilloscope with an algorithm calculation result;
c, repeatedly carrying out a plurality of simulated expiration processes on each standard volume-time waveform curve in a standard atmospheric pressure environment, and recording all data; calculating residual errors and residual error percentage according to the following formula:
Deviation＝average-standard；
mean-standard deviation
Percentage deviation＝100％×(average-standard)/standard；
Degree of deviation is 100% × (average value-standard value)/standard value
D, evaluation mode of maximum expiratory first second expiratory volume and forced vital capacity:
considering the error of standard equipment, the allowable error of capacity calculation is +/-3.5% or +/-0.1L of the reading, and a large value is taken; under the condition of not considering the error of a calibration instrument, the allowable capacity calculation error is +/-3.0% or +/-0.05L of the reading, and a large value is taken;
e evaluation mode of expiratory flow peak:
taking into account the error of the standard equipment, the allowable flow error is + -12% or + -25L-min of the reading-1Taking a large value; if standard equipment errors are not considered, the allowable flow error is + -10% or + -20L-min of the reading-1Get bigThe value is obtained.
Compared with the prior art, the invention has the following advantages: on the basis of the theory of a steady-state gas vortex flow model, the frequency coefficient adjusting algorithm based on peak point detection is provided based on the double-blade shaft tip type gas flow turbine. The problem of large calculation error of the expiratory volume is solved, and the acceptability of the volume calculation result is improved.
Detailed Description
The following examples are given to further illustrate the embodiments of the present invention. The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.
On the basis of a theory of a steady-state gas turbine flow model, a frequency coefficient adjusting algorithm based on peak point detection is provided based on a double-blade shaft-tip gas flow turbine, so that expiratory volume calculation errors caused by two problems are solved, the acceptability of a volume calculation result is improved, and respectively (1) an imposed expiratory signal belongs to a time-varying signal, and an existing turbine flow calculation model is a steady-state model and cannot accurately model the relation between the change of the turbine rotation angular frequency and the change of the imposed expiratory signal. (2) Due to the rotational inertia of the turbine, in the forced lung function test, the calculation results of the same FVC twice before and after are prone to be deviated due to the difference of the flow density distribution in the forced expiration process, and the deviation value is not within an acceptable range.
The volumetric flow model based on the turbo sensor is a linear model in a state where the gas smoothly flows at a constant flow rate:
Figure BDA0003355965080000061
Qv-a volume flow rate;
ω -turbine rotational angular velocity;
Figure BDA0003355965080000062
-a turbineThe flow conversion coefficient of (1).
Wherein
Figure BDA0003355965080000063
Z-number of turbine blades;
θ — turbine blade angle;
r-blade radius;
ρ — represents the fluid density;
a-is the cross-sectional area of the fluid;
Tr-is the rotational resistance torque.
The conversion coefficient is a variable which changes along with the flow, and linear, nonlinear and constant intervals exist in the conversion coefficient according to the flow of the fluid. Assuming that the conversion coefficient is a constant, the total volume of gas over time t can be obtained by integrating equation (1.1):
Figure BDA0003355965080000071
f-turbine rotational frequency;
n-number of revolutions of turbine in 1 test run.
Order to
Figure BDA0003355965080000072
Figure BDA0003355965080000073
Substituting formula (1.3) to obtain:
V＝KN (1.5)
according to the theorem of angular momentum:
mrv＝Jω＝2πf (1.6)
m-mass of gas flowing through the cross section per second;
v-the circumferential component of the absolute velocity of the gas;
j-moment of inertia.
Equation (1.6) shows that the rotational frequency of the turbine can be used to measure the magnitude of inertia. In the forced lung function test, the turbine rotation frequency is a function of time, after discretization, a frequency sequence is formed, and a rotation frequency penalty term is added by combining the formula (1.5), so that an improved forced expiratory volume model is obtained:
Figure BDA0003355965080000081
fi-representing a turbine rotational frequency;
αi-the adjustment factor of the frequency point;
η — bias constant.
To find N and fiFirstly, carrying out multipoint averaging on input collected data:
Figure BDA0003355965080000082
n-data points;
m is the window size;
i-input data point set;
On-outputting a set of data points;
let ThTo the deviation threshold, the following operations are performed:
Figure BDA0003355965080000083
discard all OnA zero point, a new data column O (new) is formednThen the value of N is calculated as follows:
Figure BDA0003355965080000084
Figure BDA0003355965080000085
next, all satisfy O (new)n-2＜O(new)n-1＜O(new)n> O(new)n+1>O(new)n+2The n values of the conditions are added into the sequence P (i) in ascending order, and the value range of i is 1, 2 and 3 … W. F is theniThe calculation method of (2) is as follows:
Figure BDA0003355965080000091
bringing (1.10) and (1.11) into (1.7) gives:
Figure BDA0003355965080000092
the formula 1.12 is an improved turbine gas flow volume calculation model, the FEV1 can be obtained by substituting the data of the first second according to the data length, and the FVC can be obtained by participating in the calculation of all the data. PEF can be calculated by the following formula: forced Vital Capacity (FVC), Peak Expiratory Flow (PEF), maximum expiratory first second expiratory volume FEV1
Figure BDA0003355965080000093
Wherein A and B are constants.
The turbine type lung function instrument selects a double-blade axial tip turbine with a transparent wall, the blades are light and thin, the flow resistance is extremely small, and when the flow is 14L/s, the flow resistance is less than 0.15 kPa.L-1· s-1And the requirement of the ATS/ERS on the flow resistance of the equipment can be met. A pair of photoelectric pair tubes are arranged at opposite positions on two sides of the turbine and used for converting mechanical rotation signals of the turbine into electric signals. Selecting an infrared photoelectric pair tube of SIM-012SBT97 (Rome, Japan) packaged in a lateral horizontal mode, wherein an emission tube can emit infrared light with the wavelength of 950 nm. In order to adapt to the response time of the photosensitive tube, the mounting position of the photoelectric tube needs to be centered relative to the size of the single-side blade of the turbine. The voltage signal of the photosensitive diode is converted into digital signal by an ADC in a Microcontroller (MCU) after passing through a filter circuit for further processingAnd (4) calculating.
Generating a square wave signal with the flow rate ranging from 1L/sec to 14L/sec by using a PWG-33BT breathing simulator (Piston, Hungary), performing fitting calibration on the formulas (1.12) and (1.13) based on the data, and calculating each coefficient so as to construct a capacity calculation model.
The method comprises the steps of simulating a real forced lung function test by using a 3L calibration barrel, randomly carrying out 10 groups of gas propulsion experiments with different speeds and different capacities, simultaneously recording electric signals output by a sensing mechanism by using a digital oscilloscope (KEYSIGHT, the United states), and comparing the number of wave crests or wave troughs detected by the digital oscilloscope with an algorithm calculation result to evaluate the accuracy of the algorithm.
Under the environment of standard atmospheric pressure, the simulated exhalation process is repeatedly carried out for five times on each standard volume-time waveform curve, and all data are recorded. Calculating the residual error and the percentage of the residual error according to the following formula:
Deviation＝average-standard；
mean value-standard value (1.26)
Percentage deviation＝100％×(average-standard)/standard；
Degree of deviation is 100% × (average value-standard value)/standard value (1.27)
The allowable capacity calculation error is + -3.5% or + -0.1L of the reading, taking into account the error of the standard equipment. If the error of the calibration instrument is not considered, the allowable error of the capacity calculation is +/-3.0% or +/-0.05L of the reading, and a large value is taken. FEV1 was evaluated in the same manner as FVC. For PEF, the allowable flow error is + -12% or + -25L-min of the reading, taking into account the error of the standard equipment-1And taking a large value. If standard equipment errors are not considered, the allowable flow error is + -10% or + -20L-min of the reading-1And taking a large value.
The foregoing is only a preferred embodiment of the present application, and it should be noted that, for those skilled in the art, several modifications and substitutions can be made without departing from the technical principle of the present application, and these modifications and substitutions should also be regarded as the protection scope of the present application.

Claims (10)

1. A method for calculating lung function parameters based on a turbo type lung function instrument is characterized by comprising the following steps:
s10 inputting the collected data to carry out moving average processing to obtain a new data column O (new)n；
S20, removing low threshold data and sparsifying the data;
s30 finding a peak point;
s40 calculating an adjustment coefficient alpha according to the frequency of the peak pointi；
S50 substitutes data into the following expiratory volume model:
Figure FDA0003355965070000011
wherein:
Figure FDA0003355965070000012
phi is the flow conversion coefficient of the turbine, N is the number of revolutions of the turbine in 1 test process, alphaiAs the adjustment factor of the frequency point, fiIs the turbine rotation frequency, η is the bias constant;
the forced vital capacity, peak expiratory flow and maximum expiratory first second expiratory volume are calculated.
2. The method for calculating lung function parameters of a turbo pulmonary function machine according to claim 1, wherein the step S10 comprises:
s11 performs multipoint averaging on the acquired data,
Figure FDA0003355965070000013
wherein: n is the data point, m is the window size, InFor input of a set of data points, OnIs a set of output data points;
s12 establishing a deviation threshold ThTo generate a newData column O (new)n，
Figure FDA0003355965070000021
3. The method as claimed in claim 2, wherein when the new data sequence O (new)nSatisfy O (new)n-2＜O(new)n-1＜O(new)n＞O(new)n+1＞O(new)n+2When τ is 1;
Figure FDA0003355965070000022
4. the method as claimed in claim 1, wherein f in the step S50 is a parameter of lung function calculated by a turbo-type pulmonary function machineiThe calculation method of (2) is as follows:
all satisfy O (new)n-2＜O(new)n-1＜O(new)n＞O(new)n+1＞O(new)n+2Adding the n value of the condition into the sequence P (i) in ascending order, and setting the value range of i at the time as 1, 2, 3 … W;
Figure FDA0003355965070000023
5. the method for calculating lung function parameters based on turbo-type pulmonary function machine according to claim 4,
Figure FDA0003355965070000024
w-1, wherein i ═ 1, 2, 3.; a and B are constants.
6. A lung function parameter measuring device, comprising:
the double-blade shaft tip type turbine comprises a double-blade shaft tip type turbine, wherein photoelectric geminate transistors are arranged at opposite positions on two sides of a turbine of the double-blade shaft tip type turbine and can convert mechanical rotation signals of the turbine into electric signals;
the respiration simulator can generate a square wave signal with the flow rate ranging from 1L/sec to 14L/sec, and can be used for fitting and calibrating the expiratory volume model and the expiratory flow peak formula in claim 5 based on the square wave signal to construct a volume calculation model.
7. A lung function parameter measuring device according to claim 6, wherein the vane of the two-vane axial tip turbine has a flow resistance of less than 0.15 kPa-L at a flow rate of 14L/s-1·s-1。
8. The pulmonary function parameter measurement device of claim 6, wherein the photoelectric pair tube is a SIM-012SBT97 infrared photoelectric pair tube packaged in a lateral-lying manner, the infrared photoelectric pair tube comprises a transmitting tube and a receiving tube, and the transmitting tube can transmit infrared light with a wavelength of 950 nm.
9. A lung function parameter measuring device according to claim 6, wherein said photoelectric pair is centrally located with respect to the size of a single side blade of said turbine.
10. A method for checking the accuracy of a measuring device according to any of claims 6 to 9, characterized in that it comprises the following steps:
a, simulating a real forced lung function test by using a calibration barrel, and randomly performing a plurality of groups of gas propulsion experiments with different speeds and different volumes;
b, recording the electric signals output by the sensing mechanism by using a digital oscilloscope, and comparing the number of wave crests or wave troughs detected by the digital oscilloscope with an algorithm calculation result;
c, repeatedly carrying out a plurality of simulated expiration processes on each standard volume-time waveform curve in a standard atmospheric pressure environment, and recording all data; the residual, and the percentage of residual, is calculated as follows:
deviation value is mean value-standard value;
degree of deviation is 100% × (average-standard value)/standard value;
d, evaluation mode of maximum expiratory first second expiratory volume and forced vital capacity:
considering the error of standard equipment, the allowable error of capacity calculation is +/-3.5% or +/-0.1L of the reading, and a large value is taken; under the condition of not considering the error of a calibration instrument, the allowable capacity calculation error is +/-3.0% or +/-0.05L of the reading, and a large value is taken;
e evaluation mode of expiratory flow peak:
taking into account the error of the standard equipment, the allowable flow error is + -12% or + -25L-min of the reading-1Taking a large value; if standard equipment errors are not considered, the allowable flow error is + -10% or + -20L-min of the reading-1And taking a large value.
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115995282A (en) * 2023-03-23 2023-04-21 山东纬横数据科技有限公司 Expiratory flow data processing system based on knowledge graph

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115995282A (en) * 2023-03-23 2023-04-21 山东纬横数据科技有限公司 Expiratory flow data processing system based on knowledge graph

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