Figure 1.

Establishing trajectories for maturation of respiratory function during childhood. Respiratory function can be expressed as population centiles, and during the preschool years individual children typically track on the same respiratory function centile (dark lines) defined by their personal centile at birth. Experiencing recurrent inflammatory events of sufficient intensity and duration to perturb ongoing growth/differentiation of lung tissues can result in non-reversible tissue remodeling, accompanied by stepwise dropping to progressively lower levels of lung function. The figure exemplifies an infant who is in the 49th centile at birth, who after three such severe events has declined to the 44th centile.