Longitudinal study of lung mechanics in normal infants.

Lung mechanics and partial forced expiratory flows were measured serially in seven normal infants during the first year of life. Lung mechanics were measured by the end inspiratory occlusion technique and partial forced expiratory flows by the rapid chest compression method. Thoracic gas volume, compliance, and partial forced expiratory flows measured at functional residual capacity progressively increased with age and correlated with height cubed. Respiratory system resistance progressively fell whereas volume-corrected flows remained fairly constant over the study period. These findings provide longitudinal lung function data and support the concept of isotropic lung growth.