[Bronchial hyperreactivity to distilled water].

For an epidemiological study 446 children were challenged with distilled water. The protocol consisted of 10 minutes tidal inhalation of an ultrasonically nebulized aerosol of distilled water. For children presenting with a clinical diagnosis of asthma the odds ratio for a positive challenge test was 9.1 compared to non-asthmatics [95% confidence intervals: 2.4-34.9; p = 0.001]. Symptoms cough (p = 0.03), cough at night (p = 0.03) and atopy defined by prick-test (p = 0.001) were also significantly associated with a positive challenge. The easy conduct of our protocol, the--from a pathophysiological point of view--"close to asthma" stimulus, and the small number of side-effects, indicate that the challenge with distilled water can be regarded as an alternative to metacholine provocation testing.