Bronchial challenge with hypertonic KCl solution in the diagnosis of bronchial asthma. A comparison with the challenge performed by inhalation of distilled water.

97 symptom-free asthmatics, 56 patients with chronic bronchitis and 32 healthy persons were challenged by inhalation of ultrasonically nebulised hypertonic KCl solution. 24 patients out of the group of asthmatics were challenged also by the inhalation of distilled water to compare its bronchial effect and diagnostic value in bronchial asthma with those of hypertonic (10%) KCl solution. KCl solution caused positive bronchial reaction in each patient with asthma after less than 100 inhalations. The increase of airway resistance (Raw) showed a dose dependence in contrary to bronchitics and healthy persons who failed to show any positive bronchial reaction in any of the cases. Distilled water induced a much lower increase in Raw than 10% KCl solution in the same doses inhaled in each patient with asthma, i.e. more inhalations (longer time) were needed to reach a positive bronchial reaction. The bronchial sensitivity against KCl solution and distilled water did not show clear-out parallelism. The results suggest that the positivity of challenge test performed by the inhalation of hypertonic KCl solution - similarly to that of distilled water (published by others) - seems to be specific for asthma. Challenge test performed with 10% solution has advantages relative to that performed by distilled water, primarily because of the non negligible proportion of false negativity of the latter in the group of asthmatics.