Comparison of the provocative concentration of methacholine causing a 20% fall in FEV1 between the AeroEclipse II breath-actuated nebulizer and the wright nebulizer in adult subjects with asthma.

Abstract

The American Thoracic Society guidelines for methacholine testing for the diagnosis of asthma recommends the 2-minute tidal breathing protocol with the Wright nebulizer, which produces more aerosol than required, generates a small particle size, and requires cleaning between tests. To evaluate methacholine testing using a disposable, breath-actuated AeroEclipse II, which produces aerosol during inspiration and was developed for single-patient use. Forty-six adult subjects with asthma (19 men), aged 27.3 (SD, 9.5) years, with FEV1 98.5 (SD, 18.1) % predicted participated in a randomized, crossover, observational study. Subjects were first screened using the Wright nebulizer, then assigned to 2 minutes of tidal breathing from the Wright or 20 seconds of tidal breathing from the AeroEclipse nebulizer on 2 separate days, in random order. Provocative concentration of methacholine causing a 20% fall in FEV1 (PC20) values were calculated by linear interpolation of log dose-versus-response curves, log-transformed, and compared using paired Student t test and Pearson correlation. The 38 subjects demonstrating reproducible PC20 measurements of within 1.5 doubling concentrations were included in the comparison. The geometric mean methacholine PC20 measured with the AeroEclipse nebulizer was approximately 1 doubling concentration lower than the geometric mean methacholine PC20 of the Wright nebulizer (P < 0.05). The Pearson correlation coefficient between the two nebulizers was 0.86 (P < 0.05). The PC20 measurements using the two nebulizers were highly correlated; however, the PC20 determined with the AeroEclipse nebulizer was significantly lower than those determined using the Wright nebulizer. Clinical trial registered with www.clinicaltrials.gov (NCT 01919424).