Aerosol Guide - AARC.org

2. Mechanical Breath-actuated: The AeroEclipse II ® (Monaghan Medical Corporation,
Plattsburgh, NY) is an example of mechanical breath-actuated nebulizers. As shown in
Figure 9, the mechanical breath-actuated nebulizer has a breath-actuated valve that triggers
aerosol generation only during inspiration and eliminates the need for a storage bag or
reservoir. Patients create an inspiratory force to trigger the nebulizer. Therefore, the sensitivity
of this mechanism makes it suitable only for older children and adults.
air intake
(spring-loaded valve)
Figure 9. Schematic illustration of the
function of a mechanical breath-actuated
nebulizer (From Reference 37, with permission)
exhale
inhale
power gas
3. Microprocessor Breath-actuated: The final type of breath-actuated jet nebulizer is more complex
but more appropriate to a wider range of users. In this type, compressor-driven jet
nebulizers are actuated by an electronic circuit, commonly triggered by a pressure transducer
sensing inspiratory effort. For several decades these devices have been used in pulmonary
function and research labs to administer precise boluses of aerosol for methacholine challenge.
A newer generation of “smart” microprocessor-controlled breath-actuated nebulizers
uses computer programs and sensing technology to control the pattern of aerosol generation
and even to calculate and track the delivered dose. The I-neb AAD ® system (Philips
Respironics) is one model of the microprocessor, breath-actuated that uses vibrating mesh
nebulization.
Ultrasonic Nebulizers
Ultrasonic nebulizers convert electrical energy to high-frequency vibrations using a transducer.
These vibrations are transferred to the surface of the solution, creating a standing
wave that generates aerosol (Figure 10). Ultrasonic nebulizers were initially introduced as
large-volume nebulizers most commonly used to deliver hypertonic saline for sputum
inductions. Small-volume ultrasonic nebulizers are now commercially available for delivery
of inhaled bronchodilators but should not be used with suspensions such as budesonide.
Ultrasonic nebulizers tend to heat medication. This raises concerns about disrupting proteins,
but that does not affect commonly inhaled medications. The MicroAir ® Ultrasonic
Model (Omron Healthcare, Bannockburn, IL) and MABISMist II (Mabis Healthcare,
Waukegan, IL) are different models of the ultrasonic nebulizer.
16 American Association for Respiratory Care A Guide to Aerosol Delivery Devices for Respiratory Therapists, 3rd Edition © 2013