Aerosol release, distribution, and prevention during aerosol therapy: a simulated model for infection control

Background: Aerosol therapy is used to deliver medical therapeutics directly to the airways to treat respiratory illnesses. A potential side-effect of this form of treatment is the release of fugitive aerosols into the environment and the exposure of caregivers, other patients, and bystanders to potential viral infections. The aim of this work was to use both flow visualisation and aerosol particle characterisation techniques to study the dispersion, concentrations and size distributions of fugitive aerosols emitted during aerosol therapy delivered via a standard mouthpiece.Methods: Aerosol therapy was delivered via a nebuliser, aerosol holding chamber and mouthpiece to a spontaneously breathing adult patient model that could mimic the release of patient-derived bioaerosol. A combination of laser and Schlieren imaging were used to non-invasively visualise the release and dispersion of fugitive aerosol particles. Time varying aerosol particle number concentrations and size distributions were measured with optical particle sizers at clinically relevant positions. Results: The addition of a capture filter to the expiratory port of the mouthpiece significantly reduced the release and spread of fugitive aerosols. Capture filters were effective in curtailing the release of fugitive aerosols of respirable size, ≤ 5 µm in diameter (P ≤ 0.05). Conclusions: The findings suggest that, where possible, capture filters should be added to the expiratory ports of all aerosol therapy devices to prevent airborne transmission of respiratory illnesses and create safer conditions for healthcare workers and patients.