A kind of method of controlling ventilation air leakage based on pressure waveform estimated capacityTechnical field
The invention belongs to the evaluation method of a kind of respirator volume control ventilation air leakage, be specifically related to a kind of method of carrying out the estimation of volume control ventilation air leakage based on pressure waveform and peak value thereof.
Background technology
Respirator is the necessary armarium that rescues patients with respiratory failure, treatment respiratory system disease, can be by the noinvasive ventilation realization that has wound ventilation or wear the ventilation interfaces such as face shield, oronasal mask of tracheal intubation formula, main ventilating mode comprises volume control ventilating mode and pressure controlled ventilation pattern.Although noinvasive ventilation because of its without carry out tracheal intubation, patient tolerability good, be difficult for causing the advantages such as Secondary cases injury of lung, be applied to just more and more family and clinical, yet gas leakage is inevitable problem in noinvasive ventilation.Gas leakage may cause patient's hypoventilation, reduce ventilation toleration, have a strong impact on ventilatory effect, even possibility life-threatening therefore carries out real-time gas leakage and estimates and carry out corresponding gas leakage compensation to be the key issue in noinvasive venting process under noinvasive aeration status.The present invention has built the evaluation method that a kind of respirator carries out the lower air leakage of volume control ventilation, can realize the approximate evaluation of gas leakage degree, can carry out the quantitative estimation of air leakage again, can predict in the expiratory phase of breathing cycle the air leakage in whole cycle, in order quantitatively to leak gas, compensation provides theoretical reference.The concrete steps of the volume control ventilation air leakage evaluation method the present invention relates to comprise, in volume control venting process, at air feed end, detect in real time gas circuit pressure, according to gas circuit pressure waveform feature, with reference to pressure waveform standard curve, sort out and estimate gas leakage degree, and utilizing the gas circuit pressure peak at the ventilation initial stage occurring to estimate the air leakage in the current breathing cycle according to pressure peak-air leakage relation function.
Summary of the invention
The present invention seeks to build the method for air leakage estimation in a kind of noinvasive volume control venting process, by the identification to gas circuit pressure waveform feature, the invention provides a kind of method of controlling ventilation air leakage based on pressure waveform estimated capacity.
Its step comprises, under noinvasive volume control ventilating mode, at respirator air feed end, gather gas circuit pressure signal, obtain venting pressure waveform and pressure peak, thereby the pressure waveform curve that utilization collects and pressure waveform standard curve are compared and are determined gas leakage grade, are related to that the pressure peak of utilization extraction is estimated the air leakage in this breathing cycle based on pressure peak-gas leakage.
Further, the collection of gas circuit pressure signal as above is, near being arranged in respirator suction end on the pipeline being connected with sufferer at respirator, the pressure signal that pressure transducer gathers gas circuit is set;
Further, pressure waveform as above and pressure peak by the feature of collection pressure signal, pressure waveform curve can be described by 3 characteristic points, comprising pressure peak and pressure curve descending branch flex point;
Further, pressure waveform standard curve as above be one group for distinguishing the typical pressure wavy curve of gas leakage degree, comprising under volume control aeration condition without gas leakage, a small amount of gas leakage (gas leakage is 10% below), middle amount gas leakage (gas leakage 10-35%), (gas leakage is greater than 35%) the 4 kinds of corresponding pressure waveforms of gas leakage degree that leak gas in a large number;
Further, pressure peak-air leakage relation function as above is the linear relationship of the lower gas circuit pressure peak of volume control ventilation and this breathing cycle air leakage, and its form is: Vleak=K ﹒ Pmax+ B, wherein Vleakbeing approximate air leakage in the breathing cycle, is gas circuit pressure peak, and K and B are that parameter is based on gas leakage test experience platform, on the basis of great amount of samples experiment, obtain;
Further, air leakage estimation as above is to carry out linear operation by gas circuit pressure peak being brought into pressure peak-air leakage relation function, obtains approximate air leakage in this breathing cycle.
Accompanying drawing explanation
Fig. 1 method implementing procedure figure
Fig. 2 gas circuit pressure waveform characteristic point labelling in the breathing cycle
Fig. 3 pressure waveform standard curve
Fig. 4 pressure peak-air leakage relation function curve
The specific embodiment
Below in conjunction with accompanying drawing and specific embodiment, the present invention is described in further detail.
Be illustrated in figure 1 a kind of key step of controlling the method for ventilation air leakage based on pressure waveform estimated capacity, specifically comprise:
(1) for the ventilation of respirator volume control noinvasive, at respirator air feed end, place gas pressure sensor, with venting process Real-time Collection gas circuit pressure signal;
(2) according to collected gas circuit pressure signal, form the pressure waveform curve of breathing cycle one by one, as shown in Figure 2, and gas circuit pressure signal is extracted to wavy curve characteristic point, as A point, B point, the C point that Fig. 4 marked, wherein A point is the peak point of gas circuit pressure, and B point is for being dropped to the flex point of platform section by peak point, and C point is the flex point from platform section to very fast descending branch.
(3) the gas circuit pressure waveform curve obtaining and pressure waveform standard curve are compared and then estimated gas leakage degree, as shown in Figure 3, when a small amount of gas leakage (gas leakage is less than 10%) occurs, A, B, tri-characteristic points of C are all visible, but A point declines to some extent, when continuing to increase (10%< air leakage <35%) B point while reaching medium, gas leakage degree fades away, when very large (air leakage >35%) C point of gas leakage degree fades away;
(4) according to gas circuit pressure peak, can be brought in pressure peak-air leakage relation function and calculate the approximation of trying to achieve air leakage, wherein pressure peak-air leakage relation function is first-order linear function Vleak=172Pmax+ 584, its curve as shown in Figure 4;
The method of controlling ventilation air leakage based on pressure waveform estimated capacity is based on gas circuit pressure detecting, and the serial pressure waveform standard curve of reference and pressure peak-air leakage relation function are realized.Wherein utilize detected pressures wavy curve and pressure waveform standard curve to compare the gas leakage degree that only can obtain being similar to, and utilize gas circuit pressure peak and air leakage relation function can obtain quantitative air leakage.