Bronchoconstrictive effect of ultrasonic nebulized distilled water on asthmatic children

We studied the airway responsiveness of asthmatic and normal children to ultrasonic nebulized distilled water (UNDW inhalation test). It was found that this stimulus induced a fall in FEV1 (forced expiratory volume in 1 s) in asthmatic children, but little fall in normal children. This airway response was shown to be reproducible at about 2-week intervals. The more severe the asthma, the higher the percentage of the responders to the UNDW inhalation test, and the greater the fall in FEV1. The results of the UNDW inhalation test did not correlate with that of acetylcholine inhalation test or of exercise-induced asthma (EIA). UNDW-induced bronchoconstriction was inhibited by premedication with disodium cromoglycate (DSCG) (20 mg) or inhaled ipratropium bromide (40 micrograms). Jet-nebulized distilled water induced little fall in FEV1 in asthmatic children. These data suggest that UNDW-induced bronchoconstriction may involve the release of chemical mediators from the mast cells and cholinergic pathways. We conclude that UNDW inhalation test is a safe, less burdensome, and rather convenient method to evaluate clinically nonspecific airway hyperresponsiveness in asthmatic children.