REPRODUCIBILITY OF LUNG-VOLUME MEASUREMENTS

Test reproducibility is an important consideration when interpreting r esults and should be set as a goal during data collection. Reproducibi lity criteria may need to be different for different subject groups an d are instrument and procedure-dependent. Ideally, the within-subject variability for each lung volume and measurement technique used should be established for each laboratory, These values also need to be esta blished for each different subject group (age and disease). At a minim um, test reproducibility should be monitored and controlled and each l aboratory should define their between-day reproducibility of measureme nts on at least one ''reference'' subject from ongoing periodic (e.g., weekly or monthly) measurements as part of their laboratory's quality control programme. For plethysmographic measurements functional resid ual capacity (FRC)pleth multiple determinations and a corresponding te st reproducibility criteria is probably justified.