Obstruction of the respiratory pathways, its evaluation by methods of functional examination of the lungs and development in patients with cystic fibrosis.

In 28 patients with cystic fibrosis aged 5--24 years the values of 
maximum expiratory flow rates (Vmax) at lower volume levels were assessed, 
as well as the "specific" conductance of the respiratory pathways (Gaw/TGV), 
the vital capacity (VC), total lung capacity (TLC), residual volume (RV), 
functional residual capacity (FRC), RV/TLC and FRC/TLC ratios and the one-second 
forced expiration of the vital capacity (FEV1) to evaluate obstruction of 
the respiratory pathways. Most markedly and most frequently abnormal were the 
values of Vmax, RV and of the RV/TLC ratio. These findings 
revealed that in almost all patients with CF there was already 
during the initial examination an obstruction of the peripheral respiratory pathways 
and hyperinflation of the lungs. During repeated measurement of the above 
values of lung function in 15 patients with cystic fibrosis during 
a period of 1--5 years when the patients increased in height 
by 10 cm on average, the above values did not deteriorate 
on average. There was, however, an individual variability of the investigated 
values during this period. The comprehensive treatment provided in our country 
prevented in patients with CF a deterioration of obstruction of the 
respiratory pathways during the period of investigation. 