Improvement from pulmonary hyperinflation and bronchial obstruction following sympathomimetics systemically given in infants with broncho-pulmonary diseases.

Functional disorders and efficacy of treatment with a beta-2-agonist salbutamol (Ventolin), 0.225 mg/kg bodyweight, systemically given, were evaluated by infant whole-body plethysmography in 60 infants (64 data sets) with broncho-pulmonary disease belonging to three diagnostic groups: 24 survivors after respiratory distress syndrome, 21 patients with recurrent wheezing, and 15 infants with cystic fibrosis. The values of thoracic gas volume (IGV) and airway resistance (Raw) prior to the drug administration showed a scattered distribution, which was unrelated to the 3 diagnostic groups. Therefore, stratification into 4 functional groups was performed. In 25 tests (22 infants) normal lung function (TGV less than 130% pred., Raw less than 130% pred.); in 16 tests pulmonary hyperinflation (TGV greater than 130% pred., Raw less than 130% pred.); in 10 tests hyperinflation and bronchial obstruction (TGV and Raw greater than 130% pred.); and in 13 tests (12 patients) bronchial obstruction (TGV less than 130% pred; Raw greater than 130% pred.) were found. The response to beta-2-agonists was evaluated by vector analysis (circular statistics) revealing different response groups. With respect to the initial lung function abnormality and due to a stratification into different "response groups", beta adrenoreceptor agonists showed a volume-response (decrease in end-expiratory level) in 63% of infants with pulmonary hyperinflation, a flow response (improvement of airway resistance) in 54% of infants with predominantly bronchial obstruction and a mixed-response (decrease of TGV and Raw) in 70% of infants with mixed functional abnormalities, at least if the drug is given systemically. However, distinction into functional groups and its response to a sympathomimetic agent is only possible when both, changes in TGV and concomitant changes in Raw are accurately assessed.