SERUM EOSINOPHIL CATIONIC PROTEIN-LEVELS AND BRONCHODILATOR RESPONSESAT ACUTE ASTHMA EXACERBATION

Background: Serum levels of eosinophil cationic protein are an indirec t measure of airway inflammation in asthma. It is proposed that the ex tent to which bronchoconstriction or airway inflammation contributes t o airflow obstruction in acute asthma may determine responsiveness to bronchodilator therapy. Objective: To test the hypothesis that subject s with acute asthma exacerbations who respond poorly to inhaled bronch odilator treatment may have more marked airway inflammation than those who respond well to identical therapy. Methods: Forty-eight asthmatic children who visited the emergency room due to acute exacerbations we re studied. Serum levels of eosinophil cationic protein were measured at the time of acute exacerbations and of clinical remissions. At acut e exacerbation, FEV1 was assessed before and after the administration of aerosolized salbutamol. Results: The mean serum level of eosinophil cationic protein at acute exacerbation (41.1 +/- 12.8 mu g/L) was sig nificantly higher (P <.01) than that at clinical remission (30.0 +/- 8 .5 mu g/L) in the study population. The level at acute exacerbation wa s even higher in group A (n = 18: postbronchodilator FEV1 <75% predict ed) than in group B (n = 30: postbronchodilator FEV1 greater than or e qual to 75% predicted), whereas both groups showed similar levels at c linical remission. The level at acute exacerbation correlated positive ly with severity of exacerbation (r =.47, P <.01) and negatively with bronchodilator responses (r = -.56, P <.01). This negative correlation was valid among subjects with a similar degree of exacerbation. Concl usion: A higher level of eosinophil cationic protein at acute asthma e xacerbation was associated not only with more severe exacerbation but also with a lower degree of bronchodilator responsiveness. This sugges ts that degree of airway inflammation may be one determinant of degree of responsiveness to initial bronchodilator therapy at acute asthma e xacerbation.