Asthma: the irreversible airways disease

Abstract

Chronic inflammation of the asthmatic airway leads to epithelial desquamation, goblet cell hyperplasia, mucosal and submucosal inflammation, prominent smooth muscle, and collagen deposition below the basement membrane. The changes in the airway are attributed to chronic inflammation, the healing process and subsequent remodeling. These changes contribute to three predominant mechanisms of increased airway resistance in asthma: decreased elastance of airways; increased smooth muscle in the airway which may cause increased narrowing during bronchospasm; and collagen deposition beneath the basement membrane resulting in airway wall thickening. Destruction and subsequent remodeling of the normal bronchial architecture are manifested by a progressive decline in FEV1. In an attempt to decrease the progressive decline in FEV1, studies on proper therapy have been undertaken. Antiinflammatory medications, such as inhaled corticosteroids, have been shown to decrease this rate of decline in lung function, while the effect of bronchodilators is less conclusive. Beginning treatment with inhaled corticosteroids early produces a better clinical response compared to initiating treatment late, and early treatment may prevent airway remodeling and development of irreversible structural changes.