RESPIRATORY IMPEDANCE AND DERIVED PARAMETERS IN YOUNG-CHILDREN BY FORCED RANDOM NOISE

The frequency dependenco of total respiratory impedance during spontaneous breathing was measured repeatedly in 16 children (3-5 yr old) over a 3-mnth period using forced random noise and spectral analysis. Total respiratory resistance, compliance, and inertance, which were calculated from the impedance data using regression analysis with a second-order model, had overall mean values ± SD of 5.61 ± 0.49 cmH2O xl1xs, s, 4.03 ± 1.04 ml X cmH2O-1, and 0.0120 ± 0.0024 cmH2O xl1xs2, s2, respectively. Linear regression analysis showed that resistance and compliance correlated with either height or forced vital capacity with r values in the range 0.77-0.89. Analysis of measurement variability suggested that resistance measurements had, on the average, a coefficient of variation of 15%; corresponding values for compliance and inertance measurements were 25%.