Determination of diffusing capacity by modeling the dynamics of C/sup 18/O uptake in newborns

Dynamic modeling of lung C/sup 18/O diffusion is used to measure the C/sup 18/O transfer factor (TL/sub co/) of 14 newborns aged 1-4 mo. The model equation is based on the alveolar fractions of C/sup 18/O and on changing alveolar ventilation induced by the rebreathing conditions. The model does not involve the volume of the rebreathing bag which is usually needed when applying rebreathing technique add which is a source of error. The equation is discretized and solved for recorded data obtained with equipment adapted to use in newborns. A least-square parameter calculation technique is applied to estimate TL/sub co/. Results show a strong relationship between this index and the biometrical ones and confirm those found in the literature featuring that the measurement duration can be considerably shortened.