[Cough provocation test in asthmatic children].

The effects of pH and osmolarity on cough receptors were evaluated by inhalation of aqueous aerosol in 37 children with bronchial asthma. Each of 3 different pH solutions (low 1.85-3.25, neutral 6.9-7.1, high 8.0-8.4) was combined with 3 different osmolarities (hypo 0-31, iso 254-292, hyper 830-1117 mOsm/kg), and 9 solutions were prepared. To evaluate the effect of low chloride ion concentration, neutral pH and iso-osmolar solution including low chloride ion was also prepared. These aqueous aerosols were administered from a Devilbiss 646 nebulizer for 10 seconds. Coughing was induced in 28 subjects (76%) by inhalation of low pH and hyperosmolar solution, in one subject (3%) by low pH and iso-osmolar, in one (3%) by low pH and hypo-osmolar, in three (8%) by neutral pH and hypo-osmolar, and in none by any of the other solutions. It was suggested that the alteration of pH or osmolarity alone could not induce coughing effectively, and that the combination of pH and osmolarity was the important factor for the induction of coughing.