Latent Airway Hyperresponsiveness: A Phenomenon Bordering Bronchial Asthma Definition

Abstract

The basic features of bronchial asthma are dyspnea with wheezing and objectively confirmed obstructive respiratory disorder reversible after inhalation of bronchodilators. In stable intermittent bronchial asthma, these features are not present; therefore confirmation of asthma consists of the presence of bronchial hyperresponsiveness (BHR). In the present study, there were 902 bronchoprovocation tests performed for the verification of BHR. A significant criterium for BHR is a decrease of FEV₁ of 20% from the baseline level. Every test either positive or negative was finished with inhalation of four doses of salbutamol through a spacer. We obtained 675 bronchoprovocation tests negative and 227 positive. Among the 675 subjects with a negative test there were 49 subjects who after inhalation of salbutamol had an increase in FEV₁ of ≥20% above baseline. The bronchodilatatory response of these 49 subjects, makes one think about the so-called latent bronchospasm present already at baseline, limiting further constriction during bronchoprovocation tests. The detection of such latent bronchospasm in BHR increases the number of patients with an objectively confirmed bronchial asthma from 25.0% to 30.5%. Our results suggest that bronchodilation test be performed in all patients with suspected bronchial asthma to allow detecting latent bronchospasm as an initial stage of the disease.