Non-specific broncho-reactivity obtained with an ultrasonic aerosol of distilled water

A mist of distilled water obtained by means of powerful high density ultrasonic device has been used as nonspecific challenge test for assessing bronchial hyperreactivity in asthmatics. It looks an easier and/or more physiologic stimulation when compared with the nebulisation of other substances such as histamine, acetylcholine, methacholine, carbachol, citric acid, prostaglandins. Furthermore, this test shows good correspondence to the history of fog-induced asthma. In ten normal subjects the ultrasonic mist of H2O doesn't produce any functional change, while in thirteen asthmatic patients it results in a clear-cut bronchoconstriction, with a maximal evidence within 10 minutes and a subsequent decrease up to 30 minutes. Premedication with propranolol doesn't change the negativity of the test in normal subjects. Ultrasonic mist of saline doesn't determine any remarkable bronchoconstriction in asthmatics. In forty asthmatics a trial has been then carried out on prevention of water-induced bronchoconstriction by different pharmacologic means. Ipratropium fails to protect significantly the patients, while Disodium-cromoglycate, Salbutamol and prostaglandins E reduce significantly the entity of the so induced bronchospasm. These observations support the hypothesis of a mast cell mediated mechanism and disprove the vagal contribution to this type of bronchial challenge.