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

Dynamic modeling of lung C ¹⁸O diffusion is used to measure the C ¹⁸O transfer factor (TL _co) of 14 newborns aged 1-4 mo. The model equation is based on the alveolar fractions of C ¹⁸O 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 _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.