Research On The Control Method Of Man-machine Synchronous Ventilator

In the treatment and rescue of various respiratory diseases,the ventilator plays a very important role.It has been clinically found that there are many safety problems in the process of ventilator-assisted therapy,and most of the safety problems caused are caused by the asynchrony of man-machine during ventilation.Asynchronous man-machine means that the operation of the ventilator is not synchronized with the patient’s spontaneous breathing.There are several reasons for the emergence of human-machine asynchrony.One is that the ventilation control algorithm of the ventilator is inappropriate;the other is that the patient’s own condition changes and the ventilator cannot be adjusted in real time;the third is that the patient’s ventilation needs cannot be fully understood,leading to ventilation.The parameter settings of the model are not appropriate;fourth,the artificial airway resistance changes or accidentally detached.In order to improve the man-machine synchronization of the ventilator,the paper did the following research on the man-machine synchronization of the ventilator.Based on the respiratory waveforms,five kinds of human-machine asynchronous(asynchronous)events are quantified and defined,and the inspiratory trigger time,inspiratory work(PTP),inspiratory time,peak flow rate(PIF),expiratory time,and end expiration are extracted.Positive pressure(peep)six respiratory waveform characteristics,according to human breathing rhythm and the definition of asynchronous events,a human-machine asynchronous event recognition method is proposed.Based on fuzzy logic and a ventilator prototype,with inspiratory work,inspiratory time,and expiratory time as input,positive end-expiratory pressure and inspiratory trigger threshold are output.Fuzzy control rule library is established through debugging and expert experience,Designed a set of ventilator parameter adjustment algorithm.In order to verify the asynchronous event self-recognition method and parameter adjustment algorithm,referring to the parameter requirements of the market ventilators,a complete air circuit design plan including air source,signal acquisition,medical bellows,and exhalation mask was proposed,and the STM32F103 was established.Ventilator prototype of the core board.The asynchronous recognition strategy and parameter adjustment algorithm of the ventilator were tested through the prototype.Experiments show that the developed ventilator can accurately identify five asynchronous events: invalid trigger,false trigger,double trigger,switch too early,and switch too late,and for different asynchronous events,the positive end-expiratory pressure,the percentage of exhalation switching,and the percentage of inhalation can be accurately identified.The gas trigger threshold is adjusted in real time.