Lung transfer factor for CO at rest in normal children by a steady-state method.

Lung transfer for CO (TLCO) was measured at rest in 94 normal children (47 boys and 47 girls) whose ages ranged from 3.5 to 16 years. A steady-state method, using a technique of alveolar sampling based on the equality of the mean expiratory and alveolar respiratory quotients, was employed. Highly significant correlations, statistically different for boys and girls, were fond between TLCO and standing height. TLCO was also linearly correlated with the functional residual capacity--the only pulmonary volume measurable in very young children--but without any sex difference. A multiple linear regression relates TLCO to FRC and height. Variance analysis shows the preponderant influence of FRC.