[A study of airway reactivity and nature of chronic asthmatic bronchitis].

OBJECTIVE

To observe the airway reactivity with methacholine provocation and exercise challenge of chronic asthmatic bronchitis and to assess preliminarily the nature of chronic asthmatic bronchitis.

METHODS

42 patients with bronchial asthma, 29 with simple chronic bronchitis and 27 with chronic asthmatic bronchitis were selected. The study protocol consisted of inhalation challenge with methacholine and exercise challenge. Count of blood eosinophil cells and level of blood total IgE were studied. Serum eosinophil cationic protein (ECP) concentration was measured in the asthmatic bronchitis group.

RESULTS

The positive ratio to methacholine response was 77.8% in chronic asthmatic bronchitis group, whereas the ratios were 100.0% and 41.4% in bronchial asthma and simple chronic bronchitis groups respectively. According to the response to exercise challenge, patients with chronic asthmatic bronchitis were divided into positive and negative groups. The cumulative dose of methacholine producing a 20% fall in FEV(1) (PD(20)-FEV(1)) was different between the two groups. In the positive group (9 patients), none was negative with methacholine response and PD(20)-FEV(1) being similar to the bronchial asthma group. The blood total IgE and ECP levels were significantly higher in the positive than in the negative group.

CONCLUSION

The characteristics of airway reactivity in chronic asthmatic bronchitis are midway between bronchial asthma and simple chronic bronchitis. The nature of chronic asthmatic bronchitis may be different in different patients.