Peak In- and Expiratory Flow Revisited: Reliability and Reference Values in Adults

<b><i>Background:</i></b> While peak in- and expiratory flow rates offer valuable information for diagnosis monitoring in respiratory disease, these indices are usually considered too variable to be routinely used quantification clinical practice. <b><i>Objectives:</i></b> The aim of the study was obtain reproducible measurements maximal inspiratory construct reference equations flows (PIF PEF). <b><i>Method:</i></b> With coaching effort, 187 healthy Caucasian subjects (20–80 years) performed at least 3 combined forced manoeuvres, until 2 were within 10% each other. effect on PIF preceded by a slow expiration instead repeatability over different days also investigated subgroups. Reference values limits normal PIF, mid-inspiratory flow, PEF obtained according Lambda-Mu-Sigma statistical method. <b><i>Results:</i></b> A valid could 3.3 ± 0.6(SD) attempts, resulting an overall within-test variability 4.6 3.2(SD)%. prior inspiration resulted significant (<i>p</i> < 0.001) but small increase (2.5% average). Intraclass correlation coefficient between-day 0.981 (95% CI: 0.960–0.992). Over entire age range, inter-subject smaller than previous reports, predicted based its determinants gender, age, height (<i>r</i><sup>2</sup> = 0.53). <b><i>Conclusions:</i></b> When adhering similar criteria measurement effort-dependent portions flow-volume curves, current ATS/ERS standards, it is possible use routine