Etude analytique des boucles débit/volume chez les asthmatiques et de leur application lors d’épreuves pharmacodynamiques

Abstract

Study of the influence of some parameters upon flow-volume curves and pressure-type body plethysmography during inhalation tests (acetylcholine; metaproterenol) in 10 asthmatic patients (5 males and 5 females). Although the specific conductance decreased when bronchoconstriction was induced and returned to values superior to those measured before provocation when a bronchodilator was administered, changes in specific conductance did not always parallel those of flow-volume curves (V/V), maximum expiratory volume/sec (VEMS) and mid-maximum expiratory flow rate (MMEFR). All the parameters of V/V used here are well correlated with VEMS and MMEFR but not so with the specific conductance. The inverse correlation between the time constants of V/V and residual/total pulmonary capacity (VR/CT) before provocation and the significant decrease after provocation, indicate that V 60 (or 70%) CT and V 75% vital capacity (CV) are most valuable for the evaluation of physiopathological ventilatory changes occurring in bronchoconstriction.