Irreversible airway obstruction in childhood asthma? A clinician's viewpoint.
Even though childhood asthma is assumed to comprise reversible airway obstruction, some children develop irreversible airway obstruction (not reversed by a bronchodilator or corticosteroids); this may be due to inflammation that has caused remodeling. Lately, it has been claimed that in the absence of treatment with inhaled corticosteroids, most patients will develop progressive irreversible obstruction. Several studies culminating with the Childhood Asthma Management Program (CAMP) study, which was the first randomized placebo-controlled prospective long-term study designed to test for irreversible obstruction, did not show the development of such progressive irreversible obstruction. Nevertheless, deterioration in pulmonary function does occur in some patients, probably due to inadequate anti-inflammatory treatment, and possibly also due to maintenance adrenergic treatment. Most previous studies concentrated on forced expiratory volume in 1 sec (FEV(1)), a test assessing mostly large airway obstruction. More studies are needed to investigate the presence of small airway obstruction.