The use of mouth occlusion pressure to evaluate the effect of an initial inhalation of nebulized saline in methacholine challenge.
BACKGROUND: In spite of standardization of bronchial provocation tests, some methodological aspects yet are controversial. The role of saline solution inhalation is questionable. The measurement of mouth occlusion pressure 0.1 seconds after the onset of inspiration (P0.1) is a good means of detecting a response from bronchoprovocation tests. OBJECTIVE: We investigated the value of an initial challenge with nebulized saline in subjects undergoing methacholine challenge. METHODOLOGY: Eighty-four consecutive patients clinically suspected of bronchial asthma were studied. Bronchial methacholine challenge was performed by Chatham method. P0.1 before and three minutes after saline solution inhalation were determined by the method of Whitelaw. RESULTS: There was no significant P0.1 change following the inhalation of the initial dose of nebulized saline either in those subjects who went on to produce a 20% decrement in FEV1 following a standardised methacholine challenge test, or in those subjects who proved to be non-reactors. CONCLUSIONS: We shown that no modifications are present in respiratory center function when it is assessed by measurement of mouth occlusion pressure after saline solution inhalation in methacholine challenge. This may be another reason why saline solution challenge should be omitted from bronchoprovocation challenge.