The Design And Implementation Of Auto-TriPAP Mode Household Ventilator

Many patients with overlap syndrome(OS)have apnea caused by CO2 retention and airway collapse.Due to the interaction between CO2 retention and airway collapse,the CPAP and BiPAP mode commonly used to treat sleep apnea in household ventilator is usually not ideal for patients with OS,while the Auto-TriPAP mode has more significant therapeutic effect on OS through clinical research.However,there is a lack of research on the Auto-TriPAP mode of household ventilator in China.Therefore,the design of household ventilator supporting the Auto-TriP AP mode has important research significance and application value.In addition,with the continuous development of household ventilator in the direction of informatization,it is necessary to develop the corresponding data management system.Based on the above analysis,this thesis improved the key algorithm of ventilator,studied the Auto-TriPAP mode household ventilator,and developed a ventilator data management system for managing respiratory data and patient file information.This thesis analyzed the research status of domestic and foreign household ventilator,studied the working principle,basic structure and ventilation mode of the ventilator,determined the functional requirements and technical indicators of the Auto-TriPAP mode household ventilator,and carried out in-depth research on the ventilator.The pressure control accuracy of the existing household ventilator can meet the needs of patients,but in order to further improve the pressure control performance,this thesis studied pressure control algorithm,and proposed a PID fuzzy single neuron dual-mode control scheme.For ventilator pressure control,PID control algorithm,single neuron PID control algorithm and fuzzy gain single neuron PID control algorithm are studied.Combined with the advantages of PID control and fuzzy gain single neuron PID control,a PID fuzzy single neuron dual-mode control scheme was designed.The control system was simulated by MATLAB.The indexes obtained from the response curve showed that the control effect of the dual-mode control scheme has obvious advantages over the other three control algorithms.It can make the Auto-TriP AP mode household ventilator quickly reach the set pressure and maintain higher control accuracy.The false trigger of respiratory process is one of the problems of existing household ventilator,which is easy to occur in BiPAP mode and Auto-TriP AP mode.In this thesis,a breathing triggering algorithm was designed for the false trigger.By analyzing the characteristics of the existing breathe triggering methods of ventilator,the flow threshold trigger was selected as the breathe triggering method of Auto-TriP AP household ventilator.On this basis,the end expiratory flow platform and trigger sensitivity were designed to improve and optimize the flow threshold trigger,which realized the accurate triggering of ventilator to the respiratory process and significantly reduced the number of false triggers of ventilator.In addition,the existing respirators still have the problem of unintentional leakage from the nasal mask,but the patient’s tidal volume has nothing to do with the pressure in the single level mode.Therefore,this thesis designed leakage compensation algorithm for the BiPAP and Auto-TriPAP modes.Firstly,the average leakage measurement method of ventilator was analyzed and studied.Through the further modification of this method,the inspiratory leakage measurement methods in BiPAP and Auto-TriP AP modes were obtained.According to the measured value of inspiratory leakage and the leakage threshold value,a leakage compensation algorithm was designed.By adding compensation pressure to the inspiratory pressure of ventilator,the compensation function of ventilator for unintentional leakage of the nasal mask was realized,and the leakage threshold value reduced the frequent fluctuation of pressure and improved the reliability of the ventilator.In the aspect of Auto-TriP AP mode design,according to the disease characteristics of OS patients,this thesis designed pressure relationship and ventilation regulation method for Auto-TriP AP mode.The airway pressure was designed as a lower initial expiratory pressure in the first third of the expiratory time and a higher end expiratory pressure in the second two thirds.The initial expiratory pressure is lower than the end expiratory pressure,which increases the initial expiratory pressure difference and further ensures the tidal volume of the patient.The higher end expiratory pressure can keep the patient’s airway open,enable the patient to discharge CO2 smoothly and reduce the occurrence of respiratory events.In contrast,BiPAP mode has only one pressure level in the expiratory phase,which can not achieve the therapeutic effect of Auto-TriP AP mode that takes into account CO2 retention and airway collapse at the same time.Based on the analysis and research of BiPAP mode ventilation regulation,the Auto-TriP AP mode ventilation regulation method was designed,in which the flow trigger and time control were used to switch the respiratory state and target pressure,and the function of Auto-TriP AP mode was realized.In order to apply the algorithm to ventilator,this thesis completed the software design of the ventilator control system based on embedded real-time operating system μC/OS-Ⅱ.The main program of the ventilator is designed firstly.Then,under the multi-task management and scheduling mechanism of μC/OS-Ⅱ,the design of ventilator’s pressure control task,switching breathing state task,data storage task,LCD display task and alarm task is completed,thereby realizing all functions required by the ventilator.In this thesis,a ventilator data management system is designed and developed for ventilator data.According to the detailed functional and non-functional requirements analysis of the system,the overall structure of the system is determined,and the data collection function,data display function,respiratory event recognition function,file management functionand and electronic medical record generation function development of the system are completed combined with database Mysql,which strengthening the communication between doctors and patients and providing auxiliary diagnosis and treatment methods for medical staff.Finally,this thesis tested the pressure control,respiratory triggering,leakage compensation,Auto-TriP AP mode and alarm functions of the ventilator through the actual ventilator test environment,and tested the functions of the ventilator data management system.After practical verification and testing,the functions of the Auto-TriPAP mode household ventilator in this thesis can meet the functional requirements and has high practicability.The designed algorithms and automatic three-level mode have good performance.In addition,the data management system developed for the ventilator has also achieved the designed functions and achieved the expected results.