Pulmonary function studies in bronchial asthma: I. In the control state

Abstract Pulmonary function studies were performed in forty-two patients with chronic bronchial asthma at a time when they were symptomatic. The results may be summarized as follows: (1) The vital capacity ranged between 51 and 158 per cent of predicted normal value; the inspiratory capacity: vital capacity ratio averaged 68 per cent. (2) The maximum breathing capacity ranged between 11 and 130 per cent of predicted normal value. (3) The resting ventilation was generally increased, and ranged between 3.11 and 7.52 L. per minute per square meter body surface. (4) The index of intrapulmonary mixing ranged between 1.0 and 12.12 per cent nitrogen. (5) The total lung capacity averaged 125.8 per cent of predicted normal value. The residual volume: total lung capacity ratio ranged between 35 and 67 per cent and averaged 47.0 per cent. (6) The maximum expiratory velocity averaged 3.9 L. per second.