[Comparative value of different respiratory function tests for the early diagnosis of the respiratory distress syndrome (author's transl)].

Abstract

The diagnostic value of different respiratory function tests in the respiratory distress syndrome was compared in 5 groups of subjects: healthy non-smokers, asymptomatic smokers, patients with bronchitis affecting the large bronchi, asthmatic patients between attacks, and patients with emphysema. Indices measured were the forced expiratory volume per second (FEV1), mean expiratory flow between 25 and 75% of vital capacity (MEF 25-75%), maximum instantaneous flow at 25-50-75% of vital capacity, and peak flow (Vmax 25-50-75%, PF), residual volume, expiratory resistance volume, and the curve of the alveolar plateau of expired nitrogen. The Vmax 50% and the MEF 25-75% appear to be sufficiently sensitive indices of bronchial obstruction in current practice, the MEF 25-75% being simple to measure, and presenting the advantage of not requiring complicated equipment. The Vmax 25% and the respiratory resistance volume present wide inter-individual variations, and this, together with their lack of reproducibility, limit their value in exploratory tests in isolated cases.