CN1733330A - Air supply method by triggering breathing machine by esophagus electrode diaphragmatic muscle electromyogram - Google Patents

Abstract

This invention provides method to trigger breathing machine to work by EMG comprised steps: (1) collecting EMG signal; (2) obtaining diaphragmatic muscle EMG signal from band-pass filter; (3) calculating the root-mean-square value and collecting corresponding envelope; (4) computing the slope S by linear fitting for every 50ms and the mean value M for the envelope curve within 50ms; (5) determining the slope critical value C and base line threshold T; comparing S, M, C and T on different interval, and sending trigger signal. The invention can improve synchronism between human and machine, decrease the use of dope and muscle-release agent, and the cost.

Description

The method of utilizing esophagus electrode EMGdi trigger breathing machine to supply gas

Technical field

The present invention relates to the method that a kind of trigger breathing machine is supplied gas, the method for particularly utilizing esophagus electrode EMGdi trigger breathing machine to supply gas.

Background technology

It is the important measures of rescuing the respiratory failure due to a variety of causes that the application of positive pressure respirator carries out artificial ventilation, widespread usage more and more in clinical.Man-machine synchronous finger respirator supply gas that opportunity and patient's suction defective zero-time is consistent, respirator is supplied gas process and patient's moment air-breathing demand unanimity, respirator air-breathing-expiration conversion opportunity and patient's unanimity.Assisted respiartion synchronously helps gas distribution in the lung, reduces and breathes muscle disuse atrophy, helps patient's recovery.Can the effect of synchronous assisted ventilation and comfortableness depend on reach ideal " synchronism between human and machine ".Man-machine asynchronous one side makes breathes the acting increase, and oxygen consumption increases: reduce the effect of assisted ventilation on the other hand, the patient respiratory difficulty is increased the weight of, even breathing machine ventilation can not normally carry out.Man-machine asynchronous be that traditional respirator of assisted mechanical ventilation is failed the problem of fine solution always.In order to overcome the man-machine asynchronous of inspiration trigger, in recent years, adopted flow triggering, capacity triggers and flow is followed the trail of (Flow-track) automatically the method for synchronization, increased, on certain degree, improved man-machine synchronicity than the susceptiveness of in the past pressure activated.Yet owing to after the pressure that inspiratory muscles shrink to produce must at first resist airway resistance and endogenous end expiratory positive pressure (PEEPi), could produce inspiratory airflow, trigger breathing machine is supplied gas.Thereby be contracted between the pressure that produces air flue when air-breathing or changes in flow rate from inspiratory muscles and have certain time delay.This phenomenon is particularly bright in chronic obstructive emphysema (COPD) the acute exacerbation phase, even has the part patient to employ significantly still to fail behind sternocleidomastoid or the like accessory respiratory muscle trigger breathing machine to supply gas, and causes tangible man-machine antagonism.Run into man-machine antagonism, man-machine when asynchronous clinically, can only use the muscle relaxant or the manual synchronous method of tranquilizer.The use of tranquilizer and muscle relaxant has prolonged the time that the patient stops intensive care unit(ICU) (ICU) to a certain extent, has also reduced the success rate of off line.Present various types of respirator fails thoroughly to solve man-machine antagonism, man-machine nonsynchronous problem, its key is to lack effective communication media between respirator and patient, be necessary to seek the media that comprehensively to link up patient and respirator, improve the synchronism between human and machine of respirator, improve clinical efficacy.

Summary of the invention

The objective of the invention is at existing above-mentioned of the prior art, to improve synchronism between human and machine for topic provides a kind of method of utilizing esophagus electrode EMGdi trigger breathing machine to supply gas.

For realizing stating purpose, a kind of method of utilizing esophagus electrode EMGdi trigger breathing machine to supply gas of the present invention comprises the steps:

(1) gathers diaphram EMG signal;

(2) carry out bandpass filtering and obtain diaphram EMG signal being mixed with interferential diaphram EMG signal;

(3) signal after the filtering is asked root-mean-square value RMS, can extract its envelope;

(4) method of The data linear fit in the every 50ms of envelope curve is asked slope S, and obtain the average M in the envelope curve 50ms;

(5) slope critical value of She Dinging is that C and baseline threshold of setting are T; (a) judge that whether the result who surpasses the linear fit of 250ms data continuously satisfies S＜C and M＜T, if do not satisfy, then rejudges; (b) if satisfy (a), judge then whether the result of linear fit satisfies S＞C or C＞S＞C/2 and M＞T next time,, then rejudge if do not satisfy; (c), judge then whether the result of twice linear fit satisfies M＞T down, if do not satisfy, then returns (b) to rejudge if satisfy (b); (d), judge that then whether the result of linear fit next time satisfies average M or the S＞O that average M＞last time asks, if satisfy, then produces triggering signal if satisfy (c); (e) if do not satisfy, judge then whether the result of linear fit satisfies M＞T next time,, then produce triggering signal if satisfy; If do not satisfy, then return (d) and rejudge.

Trigger breathing machine is supplied gas and adjusted the process of supplying gas: the variation → trigger breathing machine of respiratory center excitement → phrenic nerves → diaphram myoelectricity → excitement-contraction Rhizoma Nelumbinis connection → diaphram contraction → generation tension force → overcome airway resistance and PEEPi → generation airway pressure and flow is supplied gas or is adjusted and supply gas.Respirator needs certain response time (about 120-300ms) could produce suitable supplying gas after the variation that receives airway pressure or flow.The appearance of the visible diaphram myoelectricity of flow process of supplying gas from trigger breathing machine and adjustment thereof is more Zao than the pressure and the changes in flow rate of air flue.Previous experiments at us is observed: the normal person is when air-breathing beginning, the early 0.3 second time that pressure changes appears in the time ratio that the diaphram myoelectricity occurs, therefore, the diaphram myoelectricity triggers and triggers specific pressure and flow more timely, and need not overcome airway resistance and PEEPi, can reduce or eliminate trigger delay, reach synchronism between human and machine.

Diaphram EMG is a kind of reflection,plexiform, its acquisition mode has two kinds of surface electrode and esophagus electrodes, the EMG of surface electrode collection usually is subjected to factor affecting such as limb activity and has various interfering signals, and the EMG signal that esophagus electrode is gathered is relatively stable, be adapted at using among the critical patient noise main source of esophagus diaphram EMG signal: 1, the interference of ECG signal; 2, use the 50Hz power frequency of equipment to disturb; 3, the High-frequency Interference of working environment.Experimental data shows: the Energy distribution of frequency spectrum more than 90% of the diaphram signal of telecommunication is in 60～450Hz frequency band.Behind the band filter of primary signal through high frequency filter and 60～450Hz, not only High-frequency Interference can be eliminated, and the interference of low frequency electrocardiosignal and the power frequency interference of 50Hz can be eliminated.The sample frequency of EMGdi is 3000 hertz.

The present invention compared with prior art because in normal adult, the specificity and the sensitivity of electromyogram simulation triggering signal all reach 100%, trigger the opportunity specific discharge and (20 ± 50) ms early on variation opportunity occurs; Like this, in respirator with electromyogram trigger mode, can reduce patient's triggering acting, shortening patient's trigger delay time and improve synchronism between human and machine, reduce owing to man-machine asynchronous anaesthetic that uses and muscle relaxant, shorten the time of mechanical ventilation, reduce medical expense, this novel trigger mode will play a revolution of respirator trigger mode, be widely used.

Description of drawings

Fig. 1 is the control device block diagram of respirator;

Fig. 2 is a flow chart of the present invention.

The specific embodiment

The present invention is described in further detail below in conjunction with drawings and Examples, so that purpose of the present invention, feature and advantage are carried out more deep understanding.

As shown in Figure 1, the control device of respirator comprises esophagus electrode 1, signal amplifier 2, A/D converter 3, central processing unit 4 and signal output 5, and esophagus electrode 1 is positioned over esophagus, gathers the EMG signal; Signal amplifier 2 is amplified primary MEG signal, signal after the amplification is digital signal with signal by analog signal conversion behind A/D converter 3, central processing unit 4 is based on the software processes program of LabVIEW, signal is handled, and the triggering signal of sending supplies gas respirator 6 by signal output part 5 outputs.

As shown in Figure 2, step 20 is an initial state, and step 21 is a diaphram EMG signals collecting; Step 22 is that the diaphram EMG signal that is mixed with interference (mainly being that electrocardio disturbs) is carried out the bandpass filtering that passband is 60～450Hz, the diaphram EMG signal after the interference that is eliminated; Signal is by formula after the step 23 pair filtering:

$y_i=1/N{\left(\underset{j=i-N+1}{\overset{i}{\mathrm{\Σ}}}{x_j}^2\right)}^{1/2}$

Ask root-mean-square value RMS (Root Mean Square), can extract its envelope; X in the formula _jBe the output of diaphram EMG primary signal through filtering, N is a window width of asking for RMS, y _iIt is the RMS value of this segment signal.The RMS window only need move to right one and be worth, and carries out same calculating, can try to achieve next RMS value y _I+1, obtain EMG signal envelope curve at last; The method of The data linear fit is asked slope S in the every 50ms of step 24 pair envelope curve, and obtains the average M in the envelope curve 50ms; Step 25 is that a slope critical value of setting is that C and baseline threshold of setting are T, and slope critical value C is about 0.00050, and baseline threshold is that T is about 0.07, and different patients' C and T value need adjust accordingly according to the situation of baseline and slope; Find out air-breathing starting point, concrete method is: step 251, judge that whether the result who surpasses the linear fit of 250ms data continuously satisfies S＜C and M＜T, if do not satisfy, then rejudges; Step 252 if satisfy 251, judges then whether the result of linear fit satisfies S＞C or C＞S＞C/2 and M＞T next time, if do not satisfy, then rejudges; Step 253 if satisfy step 252, judges then whether the result of linear fit satisfies M＞T next time, if do not satisfy, then returns 252 and rejudges; Step 254 if satisfy 253, judges then whether the result of linear fit satisfies M＞T next time, if do not satisfy, then returns 252 and rejudges; Step 255 if satisfy 254, judges that then whether the result of linear fit next time satisfies average M or the S＞O that average M＞last time asks, if satisfy, then enters step 257 and produces triggering signal; Step 256 if do not satisfy step 255, judges then whether the result of linear fit satisfies M＞T next time, if satisfy, then enters step 257 and produces triggering signal; If do not satisfy, then return 252 and rejudge.

Claims (3)

1. a method of utilizing esophagus electrode EMGdi trigger breathing machine to supply gas is characterized in that comprising the steps:

(1) gathers diaphram EMG signal;

(2) carry out bandpass filtering and obtain diaphram EMG signal being mixed with interferential diaphram EMG signal;

(3) signal after the filtering is asked root-mean-square value RMS, extract its envelope;

(4) method of The data linear fit in the every 50ms of envelope curve is asked slope S, and obtain the average M in the envelope curve 50ms;

(5) slope critical value of She Dinging is that C and baseline threshold of setting are T; (a) judge that whether the result who surpasses the linear fit of 250ms data continuously satisfies S＜C and M＜T, if do not satisfy, then rejudges; (b) if satisfy (a), judge then whether the result of linear fit satisfies S＞C or C＞S＞C/2 and M＞T next time,, then rejudge if do not satisfy; (c), judge then whether the result of twice linear fit satisfies M＞T down, if do not satisfy, then returns (b) to rejudge if satisfy (b); (d), judge that then whether the result of linear fit next time satisfies average M or S＞0 that average M＞last time asks, if satisfy, then produces triggering signal if satisfy (c); (e) if do not satisfy, judge then whether the result of linear fit satisfies M＞T next time,, then produce triggering signal if satisfy; If do not satisfy, then return (b) and rejudge.

2. the method for utilizing esophagus electrode EMGdi trigger breathing machine to supply gas according to claim 1 is characterized in that: the passband of step (2) is 60～450Hz.

3. the method for utilizing esophagus electrode EMGdi trigger breathing machine to supply gas according to claim 1 is characterized in that: ask the formula of RMS to be:

$y_i=1/N{\left(\underset{j=i-N+1}{\overset{i}{\mathrm{\Σ}}}{x_j}^2\right)}^{1/2}$

X in the formula _jBe the output of diaphram EMG primary signal through filtering, N is a window width of asking for RMS, y _iIt is the RMS value of this segment signal.

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