Irreversibility of obstructive changes in severe asthma in childhood.

The findings in three children with severe asthma are presented. Following intensive round-the-clock therapy with theophylline (the dosage of which maintained serum levels of theophylline between 10 microgram/ml and 20 microgram/ml) and therapy with prednisone (20 mg twice daily for three weeks or more), there were improvements in spirometric and body plethysmographic measurements. Despite this therapy, abnormalities in the forced expiratory volume in one second, the maximal midexpiratory flow, the residual volume, and specific airway conductance remained. These cases represent a subgroup of asthmatic children with reactive airways who have an irreversible component to their disease.