Static and dynamic lung compliance in asthmatic symptom-free children.

The static lung compliance was studied in 27 symptom-free asthmatic children, 6-14 years old. The technique of so-called end-expiratory compliance measurement as well as that of the 'zero volume' in the balloon at barometric pressure, used in this study, have been previously discussed. The static lung compliance value is larger than the dynamic lung compliance value, this difference being larger in asthmatic than in healthy children. This difference is explained by higher static lung compliance values in asthmatic than in healthy children, whereas dynamic lung compliance values are only slightly lower in the group of asthmatic patients compared to healthy children. Static lung compliance per unit of lung volume (specific static lung compliance) is identical in both groups. Static recoil pressure at 80% of total lung capacity (TLC) is similar in asthmatic and healthy children. However, in symptom-free asthmatic children with hyperinflated lungs [functional residual capacity (FRC) higher than 25% of predicted value and FRC/TLC ratio higher than 0.45], static recoil pressure at 80% TLC is lower than the predicted value, this difference being not significant.