Use of a vibrating mesh nebulizer for allergen challenge

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.

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.

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).

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.