Lung function and bronchial responsiveness in preschool children

It is hypothesized that childhood asthma, especially when not well controlled, may constitute a risk factor for the development of COLD in adulthood (Cropp, 1985), It is unknown whether lung injury during early life is a risk factor for the development of COLD in adulthood, Asthma often starts before schoolage (Cropp, 1985), Except for the disturbing symptoms, a reason for paying attention to asthma in preschool children is the hypothesis that adequate intervention may reduce the risk of COLD in adult life (Kerrebijn, 1982). To detect lung function abnormalities at as young as possible ages suitable methods should be available. Most lung function methods can only be performed in children over 6 years of age. Lung function was measured with the forced pseudo-random noise oscillation technique (FOT) (Uindser et al., 1976a) because only passive cooperation is needed. Resistance (R,) and reactance (X,) of the respiratory system are simultaneously measured over a frequency spectrum of 2 to 26 Hz. R, is mainly determined by the patency of the upper and large airways. X, is influenced by mass-inertial and elastic properties of the respiratory system. The applicability ofFOT in preschool children was investigated. The method is now suitable for use in clinical practice to measure lung function and BR in children from about 2lfz years of age. We measured airway patency, bronchial smooth muscle tone and BR in preschool asthmatic children. Secondly, we investigated whether lung injury during early influences the development of lung function and bronchial responsiveness in children who do not have a genetic predisposition of asthma. This was investigated in children who had infant bronchiolitis, in subjects who survived infant bronchopulmonary dysplasia after neonatal respiratory distress syndrome and in individuals who experienced a near-drowning accident. The results are compared to data found in healthy controls.