Late bronchial response and increase in methacholine hyperresponsiveness after exercise and distilled water challenge in atopic subjects with asthma with dual asthmatic response to allergen inhalation

Abstract

We investigated the occurrence of late asthmatic response and increased methacholine responsiveness after exercise and ultrasonically nebulized distilled water (UNDW) inhalation in 12 subjects with asthma with dual asthmatic response and increased responsiveness after allergen challenge. On 3 separate days, allergen, exercise, and UNDW challenges were performed 2 hours after methacholine. FEV 1 was measured for 8 hours to detect any delayed change in airway caliber. If there were a further significant reduction in FEV 1 after the recovery from the immediate bronchoconstriction, methacholine challenge was performed again when FEV 1 had returned to baseline. Reproducibility of any observed late response to exercise and UNDW was also investigated by repeating these challenges on 2 subsequent days. After allergen inhalation only nine subjects had an early asthmatic response, whereas all the tested subjects demonstrated a late reaction and increased methacholine responsiveness. Ten subjects had an immediate response to exercise, and this was followed by a late response in only four patients. Nine subjects demonstrated early response to UNDW inhalation, and five subjects also had a late reaction. These late responses were associated with an increase in methacholine responsiveness in a subset of the tested subjects. Late-phase reactions to exercise and UNDW were not reproducible.