Use of a vibrating mesh nebulizer for allergen challenge

Abstract

Background: Allergen inhalation tests are a valuable research tool. The allergen dose producing an early asthmatic response (EAR) can be predicted from methacholine responsiveness and allergen skin test endpoint (STE). The Wright® jet nebulizer, which is both inefficient and increasingly difficult to obtain, has been used historically. We assessed the Solo® vibrating mesh nebulizer as an alternative for allergen and methacholine challenges.

Methods: Eighteen mild atopic asthmatics completed the study. Doubling concentration allergen prick skin tests were performed to determine the STE in allergen units/mL. The Wright® protocol was used to measure the methacholine provocation dose causing a 20% forced expired volume in one second (FEV1) fall (PD20) (μg) and the allergen PD20 (units). The Solo® protocol (0.5 mL nebulized to completion, tidal breathing inhalation) was used to determine both methacholine PD20 and allergen PD20. The nebulizer order was randomized and separated by ≥ 2 weeks.

Results: All data were log transformed. The allergen PD20, predicted from the methacholine PD20 and the STE, was within 2 doubling doses of the PD20 measured with the Wright® and 2.64 doubling doses of that measured with Solo®. The Wright® allergen PD20 correlated with the Wright® methacholine PD20 (r = 0.74) and the STE (r = 0.78) and more strongly with the product of the two (Wright® methacholine PD20 × STE, r = 0.91, p < 0.00001). The Solo® allergen PD20 showed similar relationships with the Solo® methacholine PD20 (r = 0.61), the STE (r = 0.75) and the product of the two (Solo® methacholine PD20 × STE, r = 0.83, p < 0.00002). The Wright® and the Solo® methacholine geometric mean PD20s were not significantly different (49.3 and 54.5 μg respectively, p = 0.62). The Wright® allergen PD20 was slightly but significantly lower than the Solo® allergen PD20 (geometric means 6.7 and 10.5 units respectively, p = 0.003).

Conclusion: The Solo® allergen PD20 showed the same relationship with methacholine responsiveness and STE as did the Wright®. The Solo® allergen PD20 was slightly but significantly higher than the Wright® allergen PD20. The Solo® vibrating mesh nebulizer was well tolerated and is an acceptable alternative for allergen challenge.Trial registration clinicaltrials.gov: NCT03491358.

Keywords: Allergen inhalation test; Jet nebulizer (Wright®); Methacholine inhalation test; Skin test endpoint; Vibrating mesh nebulizer (Solo®).

Conflict of interest statement

Competing interestsThe authors declare that they have no competing interests.

© The Author(s) 2019.

Figures

Fig. 1

Measured Wright® allergen PD20 (units) on the vertical axis and predicted allergen PD20 (units) on the horizontal axis both plotted in a log scale. The solid line is the line of identity and the dashed lines represent ± 2 doubling doses

Fig. 2

Wright® allergen PD20 on the vertical axis and Wright® Methacholine PD20 × STE on the horizontal axis both plotted on a log scale. The regression equation is; Log Allergen PD20 (units) = − 1.03 + 0.64 × log (Methacholine PD20 [μg] × STE [units/mL])

Fig. 3

Measured Solo® allergen PD20 (units) on the vertical axis and predicted allergen PD20 (units) on the horizontal axis both plotted in a log scale. The solid line is the line of identity, the dashed lines represent ± 2 doubling doses and the dotted lines ± 2.64 doubling doses

Fig. 4

Solo® allergen PD20 on the vertical axis and Solo® Methacholine PD20 × STE on the horizontal axis plotted on a log scale. The regression equation is; Log Allergen PD20 (units) = − 0.62 + 0.56 × log (Methacholine PD20 [μg] × STE [units/mL])

Fig. 5

Individual values for Wright® allergen PD20 on the left and Solo® allergen PD20 on the right. The red points are the geometric means with standard error bars. The Wright® allergen PD20 is slightly but significantly smaller than the Solo® allergen PD20 (6.7 vs 10.5 units respectively, p = 0.003)