Bronchial Distensibility in Asthmatic Children

Abstract

Among adult asthmatic patients distinction into "primary bronchial disease" and "emphysematic" can be made on the basis of the elastic recoil/lung conductance relationship. We wish to know if these functional distinction also could be done in asthmatic children. The lung conductance is influenced by the state of inflation of the lung and the volume history. Thus, the question arose whether lung conductance could be reliably determined taking into account the presence of trapped gas and asynchronous ventilation. Static lung compliance and lung conductance measurements were made on 23 asthmatic children. It can be demonstrated that during this manoeuvre alveolar space can be recruited, the determination of static compliance being significantly changed. In addition, elastic recoil measurements are altered by the presence of trapped gas. On the basis of these methodological considerations it was possible to divide clinically similar asthmatic children into 3 groups: 1) normal static compliance, decreased bronchial distensibility, 2) increased static compliance, better distensibility, 3) increased static compliance due to loss of elastic recoil, high distensibility. By analogy with results from adult patients we suggest that the first functional abnormalities of "emphysema" begin in childhood but remain undetected. Hence, this functional distinction may be clinically relevant, since it has been demonstrated in adults, that pharmalogical vagal blockade has an influence predominantly on central airways (Group 1), whereas betamimetics influence more the peripheral airways (Groups 2 and 3).