Developing alternative delivery systems for methacholine challenge tests.

Area of Science:

• Pulmonary Medicine
• Respiratory Physiology
• Medical Device Technology

Background:

• Current American Thoracic Society-recommended aerosol devices for methacholine challenge testing are obsolete and difficult to obtain.
• This often leads to the use of nonstandardized nebulizers, compromising test accuracy.
• There is a need for economically viable and environmentally friendly alternative devices.

Purpose of the Study:

• To evaluate the in vitro performance of potential alternative aerosol delivery devices for methacholine challenge testing.
• To assess the AeroEclipse II BAN as a replacement for the English Wright nebulizer in the 2-min tidal breathing method.
• To evaluate the VIASYS automated system as an alternative to existing methacholine challenge protocols.

Main Methods:

• Utilized a breath simulator to mimic adult and pediatric breathing patterns.
• Employed a spirometry calibration syringe for slow inhalations in the five-breath method.
• Assayed methacholine (Provocholine™) eluted from filters using high-pressure liquid chromatography.

Main Results:

• The AeroEclipse II BAN demonstrated pulmonary deposition equivalent to 2-min tidal breathing with the English Wright in 12 seconds.
• The VIASYS system required approximately 40 seconds for equivalent delivery.
• Per-breath delivery from the VIASYS and DeVilbiss 646 nebulizers was similar; one AeroEclipse II BAN breath equaled five DeVilbiss 646 breaths.

Conclusions:

• The study provides data for planning in vivo investigations.
• Modern aerosol delivery systems like AeroEclipse II BAN and VIASYS can be developed for methacholine challenge protocols.
• These findings support the transition to more reliable and standardized testing methods.