Testing Spirometers: Are the Standard Curves of the American Thoracic Society Sufficient?

BACKGROUND: The performance of spirometers is often measured only under ideal conditions, with a mechanical simulator reproducing the expiratory standard American Thoracic Society (ATS) curves generated by a computer. Studies have questioned the value of these results in real-life conditions. The aim of this study was to evaluate the accuracy and precision of 5 office spirometers with a flow-volume simulator using the ATS curves and using flow-volume curves obtained from patients. METHODS: We measured the FVC, peak expiratory flow, and FEV 1 by simulating different dynamic waveforms applied by a computer-driven syringe, the Hans Rudolph flow-volume simulator. In addition to testing standard curves recommended by the ATS, we also tested curves obtained with subjects. RESULTS: The precision of the office spirometers was good and comparable using the standard ATS curves. One device presented the best performances in terms of accuracy and precision according to the ATS recommendations, but we observed significant biases in all devices with Bland-Altman analysis, particularly with the curves obtained from subjects with severe COPD. CONCLUSIONS: The global quality of most spirometers makes them acceptable for the detection of pulmonary diseases. However, we demonstrated accuracy issues not shown by the standard testing procedure. We propose to improve the testing of spirometers by implementing more realistic flow-volume curves and to refine the analysis of the results.