Design Of The Pulmonary Ventilation Function Examination Instrument

In recent years,chronic respiratory diseases such as Chronic Obstructive Pulmonary Disease(COPD)and bronchial asthma have become very serious public health problems.Early screening and intervention are effective ways to prevent and diagnose such diseases.Among them,pulmonary function tests have been the gold standard for the diagnosis of COPD.The comprehensive large-scale pulmonary function examination instruments has a complex structure and all of them depend on imports.At the same time,it needs to establish a dedicated examination room,which is not conducive to the promotion and application in community hospitals.As a basic item for pulmonary function examination,pulmonary ventilation function eaxmination is an unavoidable test.Therefore,this artical considers designing an easy-to-operate,inexpensive pulmonary ventilation function examination instrument to achieve early screening and diagnoisis of chronic respiratory diseases such as COPD.In view of the above problems,this artical designed a pulmonary ventilation function examination instrument based on a porous orifice flowmeter and a differential pressure sensor.The actual value and the predicted value of pulmonary ventilation function indexes commonly used in clinical practice were examined under the three examination modes: slow vital capacity,forced vital capacity,and maximum voluntary ventilation.At the same time,the respiratory state curves under different examination modes are displayed,and finally it completes the individual pulmonary ventilation function examination.This article includes analysis and determination of examination principle of the instrument,detection front-end design of respiratory signal,hardware design,software design and overall calibration and test.Among them,the lower computer software completes the calculation of the actual and predicted values of the index in each examination mode.The upper computer software completes the printing of examination reports and the management of data,and the data transmission mode between lower computer and upper computer is performed through the USB to serial port.At the same time,a 7-inch LCD serial port screen is selected as the human-computer interaction interface of the instrument to realize the input of the individual’s basic personal information,completing the calculation of the individual’s predicted value,and the breathing state curve on the LCD screen can be observed after the end of each examination mode,reexaminating the unsatisfactory breathing state curve,and recalculating each index under this mode.After the three modes are checked,Through the upload button of LCD screen,we can complete the upload of personal basic information and index data of different examination modes.Based on the relevant standards and instrument calibration specifications,this artical formulates a calibration experiment scheme for the pulmonary ventilation function examination instrument,the calibration of the instrument was performed,and the calibration error basically met the requirements of the calibration specification.Meanwhile,the overall system test of the instrument is also carried out,including analysis of hospital examination result and the instrument multiple test results,it shows that the accuracy and repeatability of the instrument accords with the requirements of pulmonary function examination guidelines.It has certain application value for the prevention screening and diagnosis of chronic respiratory diseases.Finally,it summarizes the work done in this artical,pointing out the areas to be improved,and looking forward to the future direction of work.