CN104740735B - Expiration tidal volume VTE computational methods - Google Patents

Expiration tidal volume VTE computational methods Download PDF

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Publication number
CN104740735B
CN104740735B CN201310733971.2A CN201310733971A CN104740735B CN 104740735 B CN104740735 B CN 104740735B CN 201310733971 A CN201310733971 A CN 201310733971A CN 104740735 B CN104740735 B CN 104740735B
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expiration
tidal volume
vte
computational methods
time
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CN201310733971.2A
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Chinese (zh)
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CN104740735A (en
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成杰
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北京谊安医疗系统股份有限公司
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Abstract

The invention discloses a kind of expiration tidal volume VTE computational methods, include the following steps:Interval time interval of delta t ground timing acquiring expiratory gas flow data X;The variance D for calculating the collected expiratory gas flow data X of nearest n times, if the variance D becomes smaller than the default variance threshold values from more than default variance threshold values, then it is assumed that current time is finish time of exhaling, and wherein n is positive integer;The integral that the expiratory gas flow data X is in time between the expiration finish time obtained to preset expiration start time and judgement, obtains expiration tidal volume VTE.The expiration tidal volume VTE computational methods of the present invention have simple and easy to do, accurate and reliable advantage.

Description

Expiration tidal volume VTE computational methods

Technical field

The present invention relates to lung ventilator technical fields, and in particular to a kind of expiration tidal volume VTE computational methods.

Background technology

In the monitor value of lung ventilator, expiration tidal volume VTE(Expiratory Tidal Volume, are also denoted as VTe)'s Monitoring is most complicated.Especially lung ventilator is operated under flow velocity triggering pattern, and expiration phase lung ventilator can continue to provide certain Flow triggered for patient, this sampled value that may result in expiratory flow sensor includes two parts, and a part is patient's reality The tidal volume of exhalation, a part are the elementary streams that lung ventilator provides.In the ideal case, the elementary streams that lung ventilator provides are from suction Mass-air-flow sensor comes out, and then goes out from expiratory flow sensor, if patient does not trigger, the two values should be equal , it is exactly that exhalation flow rate subtracts inspiratory flow rate just equal to 0.But in real process, due to exhalation flow rate sensor and air-breathing Flow sensor is not the sensor of same model, and it is different that this may result in the flow speed value that same flow velocity samples out, This, which may result in VTE, error.

Invention content

The present invention is directed at least solve the larger technical problem of error existing in the prior art.

For this purpose, it is an object of the invention to propose a kind of accurately and reliably expiration tidal volume VTE computational methods.

To achieve the goals above, expiration tidal volume VTE computational methods according to the ... of the embodiment of the present invention, including following step Suddenly:Interval time interval of delta t ground timing acquiring expiratory gas flow data X;Calculate the collected expiratory gas flow data X's of nearest n times Variance D, if variance D becomes smaller than default variance threshold values from more than default variance threshold values, then it is assumed that current time is to exhale to terminate Moment, wherein n are positive integer;It is done in time between the expiration finish time obtained to preset expiration start time and judgement The integral of expiratory gas flow data X obtains expiration tidal volume VTE.

Expiration tidal volume VTE computational methods according to the ... of the embodiment of the present invention have simple and easy to do, accurate and reliable advantage.

In addition, expiration tidal volume VTE computational methods according to the ... of the embodiment of the present invention also have following additional technical feature:

In one embodiment of the invention, the time interval Δ t is 2-10ms, and the unit of expiratory gas flow data X is ml/s。

In one embodiment of the invention, the n values are 5-25.

In one embodiment of the invention, the variance threshold values are 30-60.

In one embodiment of the invention, the expiration tidal volume VTE computational methods are applied to turbine lung ventilator.

The additional aspect and advantage of the present invention will be set forth in part in the description, and will partly become from the following description Obviously, or practice through the invention is recognized.

Description of the drawings

The above-mentioned and/or additional aspect and advantage of the present invention will become in the description from combination following accompanying drawings to embodiment Obviously and it is readily appreciated that, wherein:

Fig. 1 is the flow diagram of expiration tidal volume VTE computational methods according to the ... of the embodiment of the present invention.

Specific implementation mode

The embodiment of the present invention is described below in detail, examples of the embodiments are shown in the accompanying drawings, wherein from beginning to end Same or similar label indicates same or similar element or element with the same or similar functions.Below with reference to attached The embodiment of figure description is exemplary, it is intended to for explaining the present invention, and is not considered as limiting the invention.

To make those skilled in the art, methods of this invention will be better understood, is done briefly to the related knowledge of lung ventilator first It introduces:

One, on lung ventilator VTE calculation formula

In expiration phase, exhalation flow rate is equal to tidal volume VTE to the integral of time.When integral, according to the difference of system It is also different to the segmentation of time.Such as in certain lung ventilator, a sampled point is taken per 5ms, then the corresponding moisture of all the points Amount mutually adds up and is equal to VTE.Such as certain is exhaled the moment, exhalation flow rate is equal to 1000ml/s, then the flow that this 5ms flows through is equal to 1000*0.005=5ml.Such as expiratory duration 1s, it is 200 sections, each section 5ms, the flow in each section 1s points It is added the value for being equal to VTE.

Two, the calculating error of VTE

In expiration phase, being triggered if it is flow velocity, lung ventilator can provide certain minimum flow, and so-called flow velocity triggers, It is exactly flow velocity trigger sensitivity of the lung ventilator according to setting, provides certain minimum flow, this minimum flow is greater than triggering Sensitivity, such as trigger sensitivity Vsens=2LPM (rising every point), the turbine lung ventilator being mentioned herein can provide the basis of 5LPM Flow, this flow enter from suction line, go out from expiration pipeline, if expiration phase is sometime, patient thinks air-breathing, Certain minimum flow will be siphoned away, may result in this way from air entry come out flow some enter Patients with Lung in, this Sample inspiratory flow subtracts expiratory gas flow and is equal to the flow that patient siphons away, if the difference after subtracting each other is more than trigger sensitivity, both Inspiratory flow rate-exhalation flow rate>2LPM, lung ventilator just lead to primary gas according to given parameter, indicate that patient triggers.

According to the calculation formula of VTE and the concept of triggering, it is not difficult to find out that the sampling of exhalation flow rate sensor includes two Point:A part is the expiratory gas flow of patient, and a part is the minimum flow that lung ventilator provides.Below by taking volume controlled pattern as an example Say the reason of VTE generates deviation.Under volume controlled pattern, tidal volume setting value VT=500ml, Vsens=2LPM.Air-breathing At the end of, lung ventilator provides the tidal volume of 500ml to patient, that is, sucks tidal volume VTI=500ml.If expiratory duration is 30s, within this 30s time, lung ventilator provides the minimum flow of 5LPM, the flow of the air entry that 30s flows through be equal to 0.5*5= 2.5L, in addition the 500ml in Patients with Lung, comes to 3L.If sampling flow of the expiratory flow sensor within this 30s time VTE=3.2L, which results in the errors of 3.2-3=0.2L.I.e.:Air-breathing tidal volume VTI=500, expiration tidal volume VTE=700, The two is unequal.Cause expiration tidal volume VTE>The reason of air-breathing tidal volume VTI is because caused by the sampling of minimum flow.It is false If patient has exhaled completion, at this time the flow velocity of exhalation vents should be equal to the flow velocity of air entry, but due to two sensors The error of sampling, for example, inspiratory flow rate sensor V_in=5LPM, V_out=5.2LPM, this 0.2LPM error, lung ventilator is just The flow velocity of patient's exhalation can be mistakenly considered.

Three, the core concept of method of the invention

Solve VTE deviations, it is necessary at the time of lung ventilator judges that patient expiration terminates, such as lung ventilator setting frequency f =10bpm (every point secondary), inspiratory duration T=1s, that expiratory duration is equal to 60/10-1=5s, but patient just exhales after being possible to 2s It is over, remaining 3s waits for next ventilation, so we need a Rule of judgment, sees when patient has exhaled, has exhaled Just no longer VTE is integrated afterwards, error can be thus reduced, may determine that whether patient expiration ties according to the variance of exhalation flow rate Beam.

Variance is the degree for describing stochastic variable and deviateing pre-estimation, and the small explanation of variance is closer to evaluation is estimated, in discrete change Variance usually is described with following formula in amount

D indicates variance, xiIndicate the value of i-th point of stochastic variable,Indicate the mean value of n point.

In the calculating of VTE, finish time of exhaling can be found using variance.If patient expiration terminates, exhalation flow rate The sampled value of sensor is the part of elementary streams, and the flow of elementary streams is more stable, and variance is smaller.If patient exhales Gas is not over, and the sampled value of that exhalation flow rate sensor can be the data slowly successively decreased from big to small, if taken several A sampled data does variance, and variance is larger.Therefore, it can judge whether patient completes exhalation process by variance size.

To achieve the goals above, expiration tidal volume VTE computational methods according to the ... of the embodiment of the present invention, including following step Suddenly:Interval time interval of delta t ground timing acquiring expiratory gas flow data X;Calculate the collected expiratory gas flow data X's of nearest n times Variance D, if variance D becomes smaller than default variance threshold values from more than default variance threshold values, then it is assumed that current time is to exhale to terminate Moment, wherein n are positive integer;It is done in time between the expiration finish time obtained to preset expiration start time and judgement The integral of expiratory gas flow data X obtains expiration tidal volume VTE.

Expiration tidal volume VTE computational methods according to the ... of the embodiment of the present invention have simple and easy to do, accurate and reliable advantage.

In addition, expiration tidal volume VTE computational methods according to the ... of the embodiment of the present invention also have following additional technical feature:

In one embodiment of the invention, time interval Δ t is 2-10ms, and the unit of expiratory gas flow data X is ml/s. Time interval Δ t is too small, means that sampling is excessively frequent, increases the workload of sensor.Time interval Δ t is excessive, has Data information may be missed so that result of calculation is inaccurate.

In one embodiment of the invention, n values are 5-25.N is too small, is likely to result in result of calculation inaccuracy, n It is excessive, cause calculation amount to be significantly increased.

In one embodiment of the invention, variance threshold values 30-60.When variance threshold values are in the value range, calculate As a result the most rationally.

In one embodiment of the invention, expiration tidal volume VTE computational methods are applied to turbine lung ventilator.

To make those skilled in the art more fully understand the present invention, below applicant do further explain in conjunction with specific embodiments It states.

Exhalation flow rate is detected using the expiratory flow sensor of turbine type lung ventilator.An expiratory gas flow is acquired every 10ms Data.Two groups of nearest 10 sampled datas are obtained two moment, then and are calculated.

First group:When exhalation process does not complete, sampled data is as shown in table 1.

1 first group of sampled data points of table

According to data as can be seen that the data of the first seven point are successively decreased, rear four data tend towards stability, and illustrate close It exhales finally.Data substitute into variance technique formula in table

N=10,D=6038 are calculated.Variance is larger, judges that exhalation process does not complete at this time.

Second group:When exhalation process is completed, sampled data is as shown in table 2.

2 first groups of sampled data points of table

According to data as can be seen that although exhalation flow rate sensor has always numerical value(It is not zero), but be not to suffer from Flow velocity caused by person's expiration, but the flow velocity that elementary streams generate.Data substitute into variance calculation formula in table

N=10,D=14 are calculated.Variance very little illustrates exhalation flow rate already close to average value, if set The variance of fixed continuous ten numbers is less than default variance threshold values 50, that is considered as patient expiration and is over, expiration tidal volume VTE's Integral just leaves it at that, no longer cumulative.Then lung ventilator ventilation next time calculates the tidal volume in next period according still further to this mode.

In the description of this specification, reference term " one embodiment ", " some embodiments ", " example ", " specifically show The description of example " or " some examples " etc. means specific features, structure, material or spy described in conjunction with this embodiment or example Point is included at least one embodiment or example of the invention.In the present specification, schematic expression of the above terms are not It must be directed to identical embodiment or example.Moreover, particular features, structures, materials, or characteristics described can be in office It can be combined in any suitable manner in one or more embodiments or example.In addition, those skilled in the art can be by this specification Described in different embodiments or examples be combined.

Although the embodiments of the present invention has been shown and described above, it is to be understood that above-described embodiment is example Property, it is not considered as limiting the invention, those skilled in the art within the scope of the invention can be to above-mentioned Embodiment is changed, changes, replacing and modification.

Claims (5)

1. a kind of expiration tidal volume VTE computational methods, which is characterized in that include the following steps:
Interval time interval of delta t ground timing acquiring expiratory gas flow data X;
The variance D for calculating the collected expiratory gas flow data X of nearest n times, if the variance D is from more than default variance threshold values Become smaller than the default variance threshold values, then it is assumed that current time is finish time of exhaling, and wherein n is positive integer;
The expiratory flow is done in time between the expiration finish time obtained to preset expiration start time and judgement The integral for measuring data X, obtains expiration tidal volume VTE.
2. expiration tidal volume VTE computational methods according to claim 1, which is characterized in that the time interval Δ t is 2- The unit of 10ms, expiratory gas flow data X are ml/s.
3. expiration tidal volume VTE computational methods according to claim 1, which is characterized in that the n values are 5-25.
4. expiration tidal volume VTE computational methods according to claim 1, which is characterized in that the default variance threshold values are 30-60。
5. the expiration tidal volume VTE computational methods according to claim 1-4, which is characterized in that the expiration tidal volume VTE Computational methods are applied to turbine lung ventilator.
CN201310733971.2A 2013-12-26 2013-12-26 Expiration tidal volume VTE computational methods CN104740735B (en)

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CN107029326A (en) * 2015-07-30 2017-08-11 沈阳昌泰医疗科技有限公司 Respiratory signal determination algorithm for positive pressure ventilation therapeutic machine

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