The Science Journal of the American Association for Respiratory Care
Standardized lung function measurements were carried out in 680 non-smoking reference subjects (327 men and 353 women), in two different centers, ten years after the original study (Bull Eur Physiopath Respir 1986;22:217-224). In 535 out of the 680 subjects, forced spirometric measurements were done twice on the same day using a water-sealed spirometer and a pneumotachograph in random order. Equipment was calibrated prior to the protocol using the flow generator system proposed by the American Thoracic Society. Daily calibration and volume checking before each study were done using a 3-L syringe. Despite that significant differences due to the type of equipment were observed in both FVC and FEV1, they only explained 2% of the interindividual variability, as compared with up to 65% of the variability explained by age and height together (50% and 15%, respectively). The variability due to the center was negligible. Reference equations for variables of forced spirometry, static lung volumes (constant-volume body plethysmography) and single-breath CO transfer capacity (DLCOsb) were obtained. It is of note that the cohort effect after ten years follow- up on FVC and FEV1 was unimportant to be taken into account. We conclude that differences in equipment together with those due to BTPS correction might likely explain a substantial portion of the variability among centers observed in the European Community Respiratory Health Survey (ECRHS) (Eur Respir J. 1994;7:954-960). The present study substantiates the similarities between forced spirometric data observed in the ECRHS and those obtained in the Barcelona's reference subjects which, in turn, confirms that the reference equations for forced spirometry proposed by the European Respiratory Society underestimate FVC and FEV1.
(Supported, in part, by 1997 SGR-086 and FIS 95-097).