[Characteristics of inspiratory flow-volume curves in children with bronchial asthma and patients with cystic fibrosis].Schweiz Med Wochenschr 1989; 119(48):1713-8SM
The characteristics of the inspiratory and expiratory flow-volume curves were measured in 77 children with bronchial asthma and 30 patients with cystic fibrosis (CF) in comparison with 19 healthy children. The aim was to explore how for children with lung diseases fulfil the physiological conditions to generate sufficient flow for optimal use of "breath actuated inhalation devices" such as the Spinhaler, Rotahaler, Turbuhaler and Diskhaler. No correlation was found between the values of inspiratory flow-volume curves and conventional lung function parameters either in healthy children or in those with lung diseases. The majority of the patients (78.6%) showed a maximal inspiratory flow, at 50% of vital capacity, (MIF50) of more than 1 l/sec, irrespective of the type of functional disorder (pulmonary hyperinflation, bronchial obstruction or both). The remaining patients (21.4%), comprising mainly patients with CF, did not reach this limit. The flows needed for correct use of the different inhalation devices vary greatly (0.4-1.6 l/sec) and the criterion of a flow lower than 1 l/sec is only fulfilled by the Turbuhaler (0.4 l/sec), the Rotahaler (0.65 l/sec) and the Diskhaler (0.8 l/sec). In contrast, the Spinhaler needs a flow of at least 1.6 l/sec. For practical purposes it seems that an MIF50 of more than 1 l/sec could be used as criterion in the indication for such inhalation devices.