Physical capacity and dyspnea in patients with asthma-like symptoms but negative asthma tests.

Ten female patients with asthma-like symptoms but negative asthma tests (study group) were compared with 10 female asthmatics in an exercise test with and without pretreatment with beta 2-stimulants. The aim was to determine whether the asthma-like symptoms in the patients of the study group could be explained by bronchoconstriction, circulatory abnormalities, or physical unfitness when provoked physically, and whether the exercise test could be used to distinguish these patients from asthmatics. Without pretreatment, the asthma group reacted with bronchoconstriction, as indicated by postexercise systematic changes in PEFR, FEV1, FVC, and SaO2, which were not seen in the study group. The groups differed in the ratings of "difficulty in getting air", as only the asthma group had significantly lower ratings when pretreated. The study group's mean test performance was 94 W; the asthma group's was 106 W. The low performance was not explained by disturbances in heart rate, electrocardiogram, or blood pressure or physical unfitness. The exercise test was found to distinguish between the groups, especially for bronchoconstriction, oxygen saturation, and ratings of dyspnea. It could be used complementary to lung function tests to eliminate bronchoconstriction, circulatory abnormalities, and physical unfitness as a cause of the asthma-like symptoms.