Regional lung function in patients with bronchial asthma.

The regional distribution of pulmonary ventilation and perfusion and regional alveolar ventilation/perfusion ratios were measured with radioactive xenon ((133)xenon) in 10 patients with asthma in remission. Four subjects had normal ventilation distribution, four had hypoventilation in some regions and normal ventilation in others, and two patients had abnormal ventilation in almost all lung regions. The lung bases were involved most frequently and the middle zones least frequently. Correlation was good between the degree of over-all ventilatory impairment calculated from (133)xenon values and measurement of the maximal midexpiratory flow rate the same day. Regions which were hypoventilated had low ventilation/perfusion ratios and also tended to be hypoperfused. In the eight subjects who had been studied similarly 5 yr previously, changes in regional function correlated in general with changes in over-all function.