[The use of the Gasthmatic System in studying bronchial hyperreactivity]

The Gasthmatic System is a new method for monitoring transcutaneously pO2 and pCO2 changes prior to, during and after bronchial provocation. Unlike normals, asthmatic and atopic subjects reproduce the same gas patterns: immediate transient hypocapnia, during inhalation of ultrasonically nebulised distilled water (UNDW) (dead space effect) and delayed more persistent hypoxia, after end of UNDW exposure. This pattern is suggestive of an uneven distribution of the alveolar ventilation and ventilation/perfusion ratio and is noted both in asymptomatic asthmatics and in nonasthmatic atopic rhinitis subjects FEV1-non-responders to UNDW. This distributional pattern, therefore, appears to be able to screen very early stages of airway disease, when conventional parameters of lung volumes and mechanics fail to reveal any significant changes in hyper-reactive response. The Gasthmatic model is simple, painless, effortless, and allows transcutaneous measurements during all the phases of the hyperreactivity test, including the actual stimulation phases. It proves, therefore, to be particularly useful for children too young to cooperate with common lung function tests.