CN104874083A - PEEP valve verification method - Google Patents

Abstract

The invention discloses a PEEP valve verification method. The method comprises following steps: collecting corresponding N signal values {y1, y2, ..., yN} of a PEEP valve under N air pressure set values {x1, x2, ..., xN}, wherein N is a positive integer; performing fitting calculation on model parameters through least square lines according to {x1, x2, ..., xN} and {y1, y2, ..., yN} so as to determine a linear model of the PEEP valve; and verifying the PEEP valve according to the PEEP valve linear model. The method is easy and convenient to carry out, is high in simulation validity, and is accurate in verification results.

Description

PEEP valve method of calibration

Technical field

This area belongs to medical instruments field, is specifically related to a kind of PEEP(positive end-expiratory pressure, end expiratory positive pressure) valve method of calibration.

Background technology

PEEP and positive end-expiratory pressure, for mechanical respirator produces malleation in inspiratory phase, gas enters pulmonary, and when end-tidal airway open, airway pressure is still kept above atmospheric pressure, subsides to prevent alveolar collapse.Play an important role when treating respiratory distress syndrome ARDS, non cardiogenic pulmonary edema, pneumorrhagia.

Respirator in the market, the control of PEEP all needs front verification, and the checking curve of some PEEP valves is linear, has plenty of nonlinear, and this is relevant with the characteristic of valve, at present ununified method of calibration.

Summary of the invention

The present invention is intended at least to solve one of technical problem existed in prior art.For this reason, the object of the invention is to propose a kind ofly to be suitable for the PEEP valve method of calibration that voltage/current-pressure curve is near-linear relation.

To achieve these goals, according to the PEEP valve method of calibration of the embodiment of the present invention, comprise the following steps: gather described PEEP valve at N number of air pressure settings { x ₁, x ₂x _nunder corresponding N number of value of electrical signals { y ₁, y ₂y _n, wherein N is positive integer; According to described { x ₁, x ₂x _nand described { y ₁, y ₂y _n, by least squares line fitting computation model parameter, determine PEEP valve linear model; And according to described PEEP valve linear model, PEEP valve is verified.

According to the PEEP valve method of calibration of the embodiment of the present invention, have simple and easy to do, simulates real solidity is good, and check results is advantage accurately.

In addition, according to the PEEP valve method of calibration of the embodiment of the present invention, also there is following additional technical feature:

In one embodiment of the invention, the described signal of telecommunication is voltage signal or current signal.

In one embodiment of the invention, described model parameter comprises: intercept parameter a ₀with Slope Parameters a ₁.

In one embodiment of the invention, the described computing formula by least squares line fitting computation model parameter is:

${\hat{a}}_0=\frac{\left(\mathrm{\Σ}{x}_i^2\right)\left(\mathrm{\Σ}{y}_i\right)-\left(\mathrm{\Σ}{x}_i\right)\left(\mathrm{\Σ}{x}_i{y}_i\right)}{N\left(\mathrm{\Σ}{x}_i^2\right)-{\left(\mathrm{\Σ}{x}_i\right)}^2}$

${\hat{a}}_1=\frac{N\left(\mathrm{\Σ}{x}_i{y}_i\right)-\left(\mathrm{\Σ}{x}_i\right)\left(\mathrm{\Σ}{y}_i\right)}{N\left(\mathrm{\Σ}{x}_i^2\right)-{\left(\mathrm{\Σ}{x}_i\right)}^2}$

Wherein, with be respectively described a ₀and a ₁best estimate, subscript i represents sequence number, and i is integer and 1≤i≤N.

Additional aspect of the present invention and advantage will part provide in the following description, and part will become obvious from the following description, or be recognized by practice of the present invention.

Accompanying drawing explanation

Above-mentioned and/or additional aspect of the present invention and advantage will become obvious and easy understand from accompanying drawing below combining to the description of embodiment, wherein:

Fig. 1 is the schematic flow sheet of the PEEP valve method of calibration according to the embodiment of the present invention.

Detailed description of the invention

Be described below in detail embodiments of the invention, the example of described embodiment is shown in the drawings, and wherein same or similar label represents same or similar element or has element that is identical or similar functions from start to finish.Be exemplary below by the embodiment be described with reference to the drawings, be intended to for explaining the present invention, and can not limitation of the present invention be interpreted as.

Purport of the present invention is that the PEEP valve verification on breathing apparatus proposes a kind of general method of calibration, and no matter PEEP valve is that Control of Voltage or Current Control are all suitable for the method.The advantage of method of the present invention realizes simply, not needing complicated mathematical model, being suitable for the voltage-pressure curve of approximately linear.

For making those skilled in the art understand the present invention better, first introduce PEEP valve operation principle.PEEP valve is in expiration air vent in respirator, is equivalent to a switch, and the size of aperture depends on the magnitude of voltage or current value that provide.Voltage is larger, and PEEP is higher.The relation of the relation approximately linear of voltage and PEEP.PEEP valve generally works when exhaling, and according to the target P EEP value arranged, provides corresponding voltage, just can ensure that the value of end expiratory positive pressure PEEP is close to settings.

Introduce curve fitting again.What in curve fitting, most fundamental sum was the most frequently used is fitting a straight line.If the functional relationship between x and y meets following linear equation:

y＝a ₀+a ₁x (1)

Two undetermined parameters are had, a in formula ₀represent intercept parameter, a ₁represent Slope Parameters.For the N group data (x that equal precision measurement obtains _i, y _i), i=1,2 ..., N, x _ivalue is considered to accurately, and all errors only in connection with y _i.Can utilize method of least square that observed data is fitted to straight line.

Point out above, during by Least Square Method parameter, require observation y _ithe weighted sum of squares of deviation be minimum, that is:

$\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{[y_i-(a_0+a_1{x}_i)]}^2{|}_{a=\hat{a}}---\left(2\right)$

Minimumly namely a is represented to parameter a( ₀, a ₁) best estimate, require observation y _ithe quadratic sum of deviation be minimum, to a ₀, a ₁ask partial derivative and make two equatioies equal 0, can a be solved ₀, a ₁value.

$\frac{\∂}{\∂a_0}\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{[y_i-(a_0+a_1{x}_i)]}^2{|}_{a=\hat{a}}=-2\underset{i=1}{\overset{N}{\mathrm{\Σ}}}(y_i-{\hat{a}}_0-{\hat{a}}_1{x}_i)=0$

$\frac{\∂}{\∂a_1}\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{[y_i-(a_0+a_1{x}_i)]}^2{|}_{a=\hat{a}}=-2\underset{i=1}{\overset{N}{\mathrm{\Σ}}}(y_i-{\hat{a}}_0-{\hat{a}}_1{x}_i)=0$

Normal equation group is obtained after arrangement

$\left\{\begin{array}{c}{\hat{a}}_{0}N+{\hat{a}}_1\mathrm{\Σ}{x}_i=\mathrm{\Σ}{y}_i\\ {\hat{a}}_0\mathrm{\Σ}{x}_i+{\hat{a}}_1\mathrm{\Σ}{x}_i^2=\mathrm{\Σ}{x}_i{y}_i\end{array}\right.$

Separate normal equation group and just can try to achieve straight line parameter a ₀and a ₁best estimate with namely

${\hat{a}}_0=\frac{\left(\mathrm{\Σ}{x}_i^2\right)\left(\mathrm{\Σ}{y}_i\right)-\left(\mathrm{\Σ}{x}_i\right)\left(\mathrm{\Σ}{x}_i{y}_i\right)}{N\left(\mathrm{\Σ}{x}_i^2\right)-{\left(\mathrm{\Σ}{x}_i\right)}^2}---\left(3\right)$

${\hat{a}}_1=\frac{N\left(\mathrm{\Σ}{x}_i{y}_i\right)-\left(\mathrm{\Σ}{x}_i\right)\left(\mathrm{\Σ}{y}_i\right)}{N\left(\mathrm{\Σ}{x}_i^2\right)-{\left(\mathrm{\Σ}{x}_i\right)}^2}---\left(4\right)$

The a obtained ₀and a ₁be exactly intercept and the slope of our linear equation, so linear equation y=a can be obtained ₀+ a ₁x.

Below in conjunction with Figure of description, technical scheme of the present invention is described.

As shown in Figure 1, according to the PEEP valve method of calibration of the embodiment of the present invention, comprise the steps:

S1. PEEP valve is gathered at N number of air pressure settings { x ₁, x ₂x _nunder corresponding N number of value of electrical signals { y ₁, y ₂y _n, wherein N is positive integer.

S2. according to { x ₁, x ₂x _nand { y ₁, y ₂y _n, by least squares line fitting computation model parameter, determine PEEP valve linear model.

S3. according to PEEP valve linear model, PEEP valve is verified.

According to the PEEP valve method of calibration of the embodiment of the present invention, have simple and easy to do, simulates real solidity is good, and check results is advantage accurately.

In addition, according to the PEEP valve method of calibration of the embodiment of the present invention, also there is following additional technical feature:

In one embodiment of the invention, the signal of telecommunication is voltage signal or current signal.

In one embodiment of the invention, model parameter comprises: intercept parameter a ₀with Slope Parameters a ₁.

In one embodiment of the invention, by the computing formula of least squares line fitting computation model parameter be:

${\hat{a}}_0=\frac{\left(\mathrm{\Σ}{x}_i^2\right)\left(\mathrm{\Σ}{y}_i\right)-\left(\mathrm{\Σ}{x}_i\right)\left(\mathrm{\Σ}{x}_i{y}_i\right)}{N\left(\mathrm{\Σ}{x}_i^2\right)-{\left(\mathrm{\Σ}{x}_i\right)}^2}$

${\hat{a}}_1=\frac{N\left(\mathrm{\Σ}{x}_i{y}_i\right)-\left(\mathrm{\Σ}{x}_i\right)\left(\mathrm{\Σ}{y}_i\right)}{N\left(\mathrm{\Σ}{x}_i^2\right)-{\left(\mathrm{\Σ}{x}_i\right)}^2}$

Wherein, with be respectively a ₀and a ₁best estimate, subscript i represents sequence number, and i is integer and 1≤i≤N.

For making those skilled in the art understand the present invention better, introduce an embodiment below in detail.

In certain PEEP valve checking procedure, plan collection ten groups of data, ask for linear fit model, then verify.

First, connect breathing circuit, and connect test lung, open proportioning valve, allow air enter lung from aspirating air pipe, slowly increase the control voltage of PEEP valve, the pressure then in sample lines.When gathering first point, if loine pressure equals 2cmH ₂about O, records the control voltage of PEEP valve now, and first point of verification that Here it is, is designated as (2, V1).Use the same method and find out the magnitude of voltage of second point, be recorded as (4, V2).The like, find out the coordinate of these ten points.Collection result is in table 1.

Table 1 sample record

Sampled point sequence number	1	2	3	4	5	6	7	8	9	10
											X(cmH2O)	2	4	6	8	10	12	14	16	18	20
Y（V）	0.1	0.21	0.29	0.42	0.5	0.63	0.7	0.78	0.83	0.92

Then, according to the formulae discovery intercept parameter a of the method for least square introduced above ₀with Slope Parameters a ₁value:

${\hat{a}}_0=\frac{\left(\mathrm{\Σ}{x}_i^2\right)\left(\mathrm{\Σ}{y}_i\right)-\left(\mathrm{\Σ}{x}_i\right)\left(\mathrm{\Σ}{x}_i{y}_i\right)}{N\left(\mathrm{\Σ}{x}_i^2\right)-{\left(\mathrm{\Σ}{x}_i\right)}^2}$

${\hat{a}}_1=\frac{N\left(\mathrm{\Σ}{x}_i{y}_i\right)-\left(\mathrm{\Σ}{x}_i\right)\left(\mathrm{\Σ}{y}_i\right)}{N\left(\mathrm{\Σ}{x}_i^2\right)-{\left(\mathrm{\Σ}{x}_i\right)}^2}$

Data are substituted into formula, obtains a ₀=0.01 and a ₁=0.0474, obtain linear equation:

Y=0.047x+0.01。

Finally, check results is verified.The ventilating mode of respirator is selected capacity ventilation, VT(tidal volume, one-period sends into the tidal volume in patient's lung)=400ml, inspiratory duration T=1s, frequency f=15, the atmospheric pressure value of PEEP sets gradually as 5cmH ₂o, 15cmH ₂o, 30cmH ₂o.Experimental result is in table 2:

Table 2 experimental result

PEEP settings (cmH 2O)	5	15	30
				Respirator PEEP monitor value (cmH 2O)	4.7	15.1	31

Substitute into equation Y=0.047x+0.01 tri-control voltages according to PEEP settings and be respectively y1=0.047*5+0.01=0.245, y2=0.715, y3=1.42.As shown in table 2, when PEEP is set to 5, ventilator value PEEP=4.7cmH2O, when arranging PEEP=15, monitor value PEEP=15.1cmH2O, when PEEP is set to 30cmH2O, machine monitoring value PEEP=31, because respirator is positive and negative 2cmH2O to the error requirements of PEEP, so PEEP controls, within accuracy rating, to meet the demands.According to monitoring result, PEEP controls, within accuracy rating, to meet the demands.

In describing the invention, it will be appreciated that, term " " center ", " longitudinal direction ", " transverse direction ", " length ", " width ", " thickness ", " on ", D score, " front ", " afterwards ", " left side ", " right side ", " vertically ", " level ", " top ", " end " " interior ", " outward ", " clockwise ", " counterclockwise ", " axis ", " radial direction ", orientation or the position relationship of the instruction such as " circumference " are based on orientation shown in the drawings or position relationship, only the present invention for convenience of description and simplified characterization, instead of indicate or imply that the device of indication or element must have specific orientation, with specific azimuth configuration and operation, therefore limitation of the present invention can not be interpreted as.

In addition, term " first ", " second " only for describing object, and can not be interpreted as instruction or hint relative importance or imply the quantity indicating indicated technical characteristic.Thus, be limited with " first ", the feature of " second " can express or impliedly comprise one or more these features.In describing the invention, the implication of " multiple " is two or more, unless otherwise expressly limited specifically.

In the present invention, unless otherwise clearly defined and limited, the term such as term " installation ", " being connected ", " connection ", " fixing " should be interpreted broadly, and such as, can be fixedly connected with, also can be removably connect, or integral; Can be mechanical connection, also can be electrical connection; Can be directly be connected, also indirectly can be connected by intermediary, can be the connection of two element internals or the interaction relationship of two elements.For the ordinary skill in the art, above-mentioned term concrete meaning in the present invention can be understood as the case may be.

In the present invention, unless otherwise clearly defined and limited, fisrt feature second feature " on " or D score can be that the first and second features directly contact, or the first and second features are by intermediary mediate contact.And, fisrt feature second feature " on ", " top " and " above " but fisrt feature directly over second feature or oblique upper, or only represent that fisrt feature level height is higher than second feature.Fisrt feature second feature " under ", " below " and " below " can be fisrt feature immediately below second feature or tiltedly below, or only represent that fisrt feature level height is less than second feature.

In the description of this description, specific features, structure, material or feature that the description of reference term " embodiment ", " some embodiments ", " example ", " concrete example " or " some examples " etc. means to describe in conjunction with this embodiment or example are contained at least one embodiment of the present invention or example.In this manual, to the schematic representation of above-mentioned term not must for be identical embodiment or example.And the specific features of description, structure, material or feature can combine in one or more embodiment in office or example in an appropriate manner.In addition, the different embodiment described in this description or example can carry out combining and combining by those skilled in the art.

Although illustrate and describe embodiments of the invention above, be understandable that, above-described embodiment is exemplary, can not be interpreted as limitation of the present invention, and those of ordinary skill in the art can change above-described embodiment within the scope of the invention, revises, replace and modification.

Claims (4)

1. a PEEP valve method of calibration, is characterized in that, comprises the following steps:

Gather described PEEP valve at N number of air pressure settings { x ₁, x ₂x _nunder corresponding N number of value of electrical signals { y ₁, y ₂y _n, wherein N is positive integer;

According to described { x ₁, x ₂x _nand described { y ₁, y ₂y _n, by least squares line fitting computation model parameter, determine PEEP valve linear model; And

According to described PEEP valve linear model, PEEP valve is verified.

2. PEEP valve method of calibration as claimed in claim 1, it is characterized in that, the described signal of telecommunication is voltage signal or current signal.

3. the PEEP valve method of calibration as described in claim 1 and 2, it is characterized in that, described model parameter comprises: intercept parameter a ₀with Slope Parameters a ₁.

4. PEEP valve method of calibration as claimed in claim 3, it is characterized in that, the described computing formula by least squares line fitting computation model parameter is:

${\hat{a}}_0=\frac{\left(\mathrm{\Σ}{x}_i^2\right)\left(\mathrm{\Σ}{y}_i\right)-\left(\mathrm{\Σ}{x}_i\right)\left(\mathrm{\Σ}{x}_i{y}_i\right)}{N\left(\mathrm{\Σ}{x}_i^2\right)-{\left(\mathrm{\Σ}{x}_i\right)}^2}$

${\hat{a}}_1=\frac{N\left(\mathrm{\Σ}{x}_i{y}_i\right)-\left(\mathrm{\Σ}{x}_i\right)\left(\mathrm{\Σ}{y}_i\right)}{N\left(\mathrm{\Σ}{x}_i^2\right)-{\left(\mathrm{\Σ}{x}_i\right)}^2}$

Wherein, with be respectively described a ₀and a ₁best estimate, subscript i represents sequence number, and i is integer and 1≤i≤N.