Pulmonary elasticity in children and adolescents.

Static (Cst(L)), dynamic (Cdyn(L)), and "specific lung compliance (CL/TLC, CL/FRC) and the elastic recoil pressure of the lungs (Pst/(L)) were measured in 131 healthy children and the adolescents (age 6 to 17 years) from simultaneous recordings of esophageal pressure and lung volume. Esophageal elastance and vertical esophageal pressure gradients were also studied. Pst(L), measured at different lung volumes (fractional) from the expiratory quasi-static pressure-volume (PV) curves of the lungs, increased significantly with increasing body height, age, and body surface. Cst(L), determined from the midportion of PV curves, and Cdyn(L) measured during normal breathing at frequencies around 20/min also increased significantly with somatic growth. "Specific" Cst(L) decreased with increasing body height, age, and body surface. "Specific" Cdyn(L), esophageal elastance, and the vertical esophageal pressure gradient were independent of body height, age, and body surface, Cdyn(L) was less than Cst(L) mainly in smaller and younger children, and was not considered a valid index of pulmonary elasticity. Values of Pst(L), "specific" Cst(L), and the change of slope of the midportion of PV curves in children and adolescents suggested developmental changes of pulmonary elasticity in man over the age range studied.