Design and Verification of a COPD Screening Equipment Based on Dual-differential Pressure Throttling Technique

This study was to design a chronic obstructive pulmonary disease (COPD) screening equipment, based on the dual-differential pressure throttling technique. The technique combined a wide range, but low-resolution ratio sensor and a narrow range, but high-resolution ratio one. It can accurately detect the indexes of forced vital capacity (FVC), forced expiratory volume in one second (FEV₁), one second rate(FEV₁/FVC (%)), and achieve them in a low-cost way. The new designed machine will be compared with a British machine, named ML-3500. The correlations of FVC and FEV₁ between new machine and ML-3500 were 0.998 and 0.999, respectively. The P values of paired t test of these two indexes were over 0.05. Bland-Altman analysis of FVC, FEV₁ and FEV₁/FVC (%) showed that more than 90% of the scatter points of the three parameters fell within the consistency interval. This machine can be used to accurately screen COPD and its low-cost would be advantage to promote in large population.