Comparative studies on nebulizers for antigen inhalation in experimental asthma

The majority of cases of allergic asthma in experimental animals have been provoked by inhalation with mist antigen. Because of the inherent inability of some species to breathe through the mouth, including guinea pigs, mice and rats, an upper airway response may be substantially involved in experimental asthma induced by antigen inhalation. With this in mind, we evaluated three types of nebulizers (a hand-made glassware pressure nebulizer (GPN), a DeVilbiss nebulizer (DN) and an ultrasonic nebulizer (UN)) with respect to their ability to adequately sensitize/challenge guinea pigs by antigen inhalation in bronchial asthma. Several solutions and suspensions, including antigen and AI(OH)3, were atomized with these three nebulizers. The results obtained were as follows: irrespective of the type of solution or suspension used, of the three nebulizers, GPN generated mists with the smallest diameter. The rank order of median diameter of the mists generated was GPN (1.6-2.1 μm) < DN (2.2-3.5 μm) < UN (4.3-4.7 μm). When Evans blue mists produced by the GPN were presented to guinea pigs, 79% of the mist trapped in the whole airway was found in the lung, while 49 and 79% of mists produced by DN and UN, respectively, were already deposited in the upper airway. These results strongly suggest that GPN is more useful for inhalation challenge in experimental asthma in animals.