Lung function and severe asthma: what do we know?

Abstract

Severe asthma represents a major burden for patients and society. Fixed airway obstruction and remodeling, together with small airway dysfunction (SAD) constitute important pathophysiological mechanisms in the genesis of severe asthma. In these patients, lung function does not correlate strongly with asthma symptoms. Several techniques have been used in functional assessment, including peak expiratory flow, spirometry, bronchoprovocation testing, body plethysmography, and SAD detection. Impulse oscillometry has been increasingly used in the diagnosis of SAD in people with severe asthma, as it allows a more comprehensive assessment of severity, monitoring, and evaluation of response to treatment. In patients with severe asthma, those with frequent exacerbations or with obesity phenotypes are characterized by worse lung function. In clinical practice, a significant increase in forced expiratory volume in the first second after bronchodilation, especially when associated with blood eosinophilia, may be a marker of accelerated decline in lung function. The increasingly widespread use of biological agents may be an important measure, being effective from the point of view of lung function in reducing static lung hyperinflation.