Customizing the Pressure-based Spirometer for Improving its Accuracy for Chronic Obstructive Pulmonary Disease Tests

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Addis Ababa University


Breathing is a fundamental and essential process for the proper functioning of human being. It is a process of supplying oxygen to the body and removing of waste carbon dioxide from the body. This process takes place through the respiratory system and organs involving the nose, pharynx, trachea, bronchi, and lungs. There are several diseases and conditions that can affect the respiratory system. Chronic obstructive pulmonary disease (COPD) is the most common one that arises from airway obstructions. A differential pressure-based spirometer is the most dominant device used to perform pulmonary function test in order to diagnose and monitor COPD. This pressure-based spirometer acquires a signal through a pressure difference between two points of the patient breathing tube (PBT) created by the patient against the atmospheric pressure. This means as the COPD patient finds it hard to breath, the differential pressure created by the patient across PBT reduces. The detection sensitivity of the PBT and altitude correction are the main important parameters which need to be considered while designing a differential pressure-based spirometry. So the aim of this thesis is to customize a differential pressure-based spirometer device with respect to altitude in order to improve accuracy of COPD tests. In this thesis, LabVIEW software has been used to generate and analyze the measured signal, and customize the spirometer with respect to altitude. Moreover, Bernoulli’s equation has been used to calculate air flowrate and forced vital capacity of the lung which are used to grade COPD test result. Finally, the designed PBT is simulated using Ansys 19.2 software and a prototype is created using 3D printer. The flowrate vs time, and volume vs time graphs were obtained and displayed using LabVIEW. The result shows that the accuracy of COPD test can be improved by increasing the sensitivity of PBT and customizing a pressure-based spirometer using the altitude correction factor during designing and operating the pressure-based spirometer.



Bernoulli’s Equation, COPD, LabVIEW, PBT, Spirometer, Lung