Reference values for functional residual capacity and maximal expiratory flow in young children.

To determine the relation of functional residual capacity and maximal expiratory flow at functional residual capacity to sex, age, height, and weight in healthy young children living in Portland, Oregon, we tested 37 boys and 36 girls using a modified helium-dilution technique and partial expiratory flow-volume curves. Within the age, height, and weight ranges studied, exponential or multiple regression techniques offered no substantial advantage over simple linear regression using height, weight, or age. There were no sex differences for the relationship between either variable and age, height, or weight. These techniques can readily be used in children as young as 3 years of age and may provide a method for studying lung growth and development in early childhood and a way to observe the progression of disease or the effect of treatment in the young child.