pulmonary disorders
Airflow, Lung Volumes, and Flow Volume Loop
Introduction
Airflow and lung volume measurements can be used to differentiate obstructive from restrictive pulmonary disorders, to characterize severity, and to measure responses to therapy. Measurements are typically reported as absolute flows and volumes and as percentages of predicted values using data derived from large populations of people presumed to have normal lung function. Variables used to predict normal values include age, sex, ethnicity, and height. Whether to correct for ethnicity is controversial. For example, historical cohorts of primarily American and European adults showed lower lung volumes in multiple non-White ethnic groups (eg, Blacks, Hispanics, Asians) than in Whites. However, environmental and other nongenetic factors are thought by some to be equally or more important than genetic differences in explaining these differences. Studies have found that unadjusted flow and volume values are more predictive of patient outcomes than ethnically adjusted values, suggesting that these adjustments may result in under-recognition (and thus undertreatment) of true decreases in pulmonary function in non-White individuals. 