Definition and assessment of asthma.

Bronchial obstruction, its reversibility, airway hyperreactivity and inflammation are key variables of asthma. In clinical practice they can be assessed with repeated noninvasive lung function measurements (spirometry and mucociliary clearance). The asthmatic inflammation in contrast to chronic bronchitis is characterized by increased IgE and eosinophils depending on the disease state (seasonal, perennial, chronic symptomatic or asymptomatic asthma). Based on the above-mentioned clinically applicable measurements, a classification of asthma, chronic (obstructive) bronchitis, and emphysema is proposed because the three groups of diseases have different etiology and need different prophylactic and symptomatic treatment.