The Long-Term Stability of Portable Spirometers Used in a Multinational Study of the Prevalence of Chronic Obstructive Pulmonary Disease

METHODS: During the survey period (which ranged from 3 months to 6 months in the various locations) we collected daily calibration data from the 70 EasyOne spirometers used in the 5 survey cities. The calibrations were conducted with a 3-L syringe, and the calibration data were stored in the spirometer’s database. RESULTS: Ninety-seven percent of the calibration volumes were within 64 mL (2.1%) of the 3-L calibration signal. Excluding data from the first city studied (São Paulo), where one calibration syringe had to be replaced, 98 % of the calibration checks were within 50 mL (1.7%). The measured volume was affected only minimally by the syringe’s peak flow or emptying time. CONCLU-SION: In these 70 EasyOne spirometers neither calibration nor linearity changed during the study. Such calibration stability is a valuable feature in spirometry surveys and in the clinical setting. Key words: spirometry, quality control, calibration, pulmonary function tests, reliability. [Respir Care 2006;51(10):1167– 1171. © 2006 Daedalus Enterprises