Quality control of vital capacity based on waveform assessment can improve defect detection in spirometer equipment

Abstract

Spirometer calibration is verified by confirming whether the measured volume meets the accuracy requirement of ±3% using a 3-L syringe. We demonstrate the effectiveness of observing the waveform on a volume–time spirogram during calibration verification to identify equipment defects. We pushed and pulled the 3-L syringe five times and checked the plateau and repeatability of the positions at full expiration and full inspiration, in addition to the measured volume. For Case 1, the measured volume was within the calibration limit, but the positions at full expiration and full inspiration gradually changed. The abnormality disappeared after the breathing tubes were replaced. For Case 2, the measured volume was also within the calibration limit, but the positions at full expiration and full inspiration gradually changed. The abnormality disappeared after replacing the adapter connecting the breathing tube to the syringe. Pushing and pulling the 3-L syringe for some time and observing the waveform during calibration verification enabled the identification of mild defects in the equipment. These are useful indicators for quality control of pulmonary function tests.