Continuous recording of the respiratory cycle with the simultaneous or sequential radionucleic exploration (gamma camera) of ventilation (¹³³Xe) and perfusion (MAT-99) was performed to determine the V/Q index in regional areas (Polaroid photography, mini-computer, memory visualization system, Benson incremental tracer, etc.) from the level of 1,024 points. An average ratio per sector was calculated and onyl three median sectors were retained. The wash-in and wash-out curves were traced by computer, and the calculation of the average T 1/2 for the different compartments of each median sector (apex – middle and base) was done in about 22 observations: in 18 diffuse emphysema, 11 of which were associated with giant cystic emphysema (spirometric, plethysmographic and radiographic data), T 1/2 values were greater than those of normal subjects (compartments C1 and C2) in diffuse emphysema and can become indefinable in zones of cystic emphysema. The values of the index V/Q approach the normal in diffuse emphysema with a tendency toward equalization of the ratios from the apex to the base. Extremely large divergence is observed in the elevated V/Q ratios in cystic emphysema. The values of the index V/Q approach the normal in diffuse emphysema with a tendency toward equalization of the ratios from the apex to the base. Extremely large divergence is observed in the elevated V/Q ratios in cystic emphysema.

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.