Characteristics and diagnostic significance of wheezes during exercise-induced airway obstruction in children with asthma.

The diagnostic significance of wheezes for childhood asthma has not been studied systematically (to our knowledge), even though alternative diagnostic methods are limited, especially with children too young for lung function testing. To fill this gap, tracheal sounds were continuously recorded of 70 school-aged children with and 30 without asthma during standardized physical exercise. Wheezes were digitally analyzed and compared with sound patterns previously recorded after histamine inhalation. Exercise-induced wheezes proved to be indistinguishable from sound patterns associated with histamine. The diagnostic sensitivity and specificity of any wheeze for a fall in FEV1 greater than 20% after exercise were, respectively, 86% and 99%. The sensitivity and specificity of any wheeze for a diagnosis of asthma were, respectively, 19% and 100%. Wheezes were often audible for a short time only, making traditional (stethoscopic) detection unlikely and thereby restricting clinical diagnostic significance. This suggests that the development of automated detection techniques may be warranted.