Two-minute tidal breathing methacholine bronchial challenge: Comparison of two jet nebulisers.

Background: The American Thoracic Society (ATS) guideline for methacholine challenge testing (MCT) recommended using the English Wright (EW) nebuliser. However, other brands of nebulisers are also indicated to be acceptable for this technique, but further validation of nebuliser performance is recommended.

Objective: To compare the methacholine provocation concentration causing a 20% fall in forced expiratory volume in 1 second (PC -FEV ) measured by using EW nebuliser and DV 646 nebuliser.

Methods: Subjects were randomly assigned to undergo 2-min tidal breathing methacholine challenge with either EW or DV 646 nebuliser on two separate days, which were at least 24 hours but not more than 7 days apart. The above procedure was repeated for each subject in 1 month, but the nebulisers were selected in a reverse order.

Results: The study includes 15 mild and stable asthmatic patients. The geometric means (SD) of methacholine PC measured with using EW and DV 646 nebulisers were 1.82 (6.38) mg/mL versus 0.83 (1.82) mg/mL, respectively in the initial two visits and 2.56 (6.29) mg/mL versus 0.78 (1.40) mg/mL in the following two visits (both P < 0.05). There are well correlations between PC20-EW1 and PC20-EW2 (r = 0.99, P < 0.01), PC20-DV1 and PC20-DV2 (r = 0.88, P < 0.01), and between PC20-EW1 and PC20-DV1 (r = 0.91, P < 0.01), PC20-EW2 and PC20-DV2 (r = 0.78, P < 0.01).

Conclusions: PC -FEV measured by using the two conventional jet nebulisers was both repeatable and the results were highly correlated.