Pulmonary function in children with asthma at acute attack and symptom-free status.

Abstract

The pulmonary function of 30 asthmatic children (22 boys and 8 girls) between 5 and 16 years of age was studied during an acute attack and in the ensuing symptom-free period. During the acute attack, all static lung volumes except vital capacity were increased, and a significant amount of gas was trapped. Airway conductance and all dynamic lung volumes were decreased. The ratios of functional residual capacity to total lung capacity and residual volume to total lung capacity were significantly elevated. Both lung diffusing capacity and mixing efficiency were significantly decreased. These deviations from normal pulmonary function were attributed to increased airway resistance and its consequences. During the symptom-free period, vital capacity returned to normal, but the other static lung volumes remained elevated. The amount of trapped gas was not significantly different from normal. All dynamic lung volumes except maximal mid-expiratory flow (MMEF25%–75%) returned to normal. Airway conductance was withi...